ECOLOGICAL ASSESSMENT

QUEENSLAND MUD CRAB FISHERY

Compiled by Shannon Ryan, Queensland Fisheries Service January 2003

With assistance from

Mark Doohan, Malcolm Dunning, Sue Helmke, Clare Bullock, Eddie Jebreen, Brad Zeller, Lew Williams, Jim Higgs and Kadesh Clarke, Queensland Fisheries

Service

and

Ian Brown, Neil Gribble, Wayne Sumpton, Steve Bailey and Stirling Peverell, Agency for Food and Fibre Sciences

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The Department of Primary Industries Queensland has prepared this report for Environment Australia for assessment under guidelines for exemption from export controls of the Environment Protection and Biodiversity Conservation Act 1999 relating to wildlife. INTRODUCTION The target species of the Queensland Mud Crab Fishery is Scylla serrata, a portunid crab variously known as mud crab, green mud crab, mangrove crab and black crab. Estuarine crabs of the genus Scylla inhabit most areas of mangrove-lined coastal habitat throughout the tropical and sub-tropical Indo-West Pacific (IWP) region. A taxonomic revision of Scylla by Keenan et al. (1998) identified four distinct species in the genus Scylla. S. paramamosain and S. tranquebarica are not found in Australian waters. S. olivacea, the brown mud crab, is found within Queensland waters in the northern part of the Gulf of Carpentaria, however the species requires low salinity estuarine habitats and therefore both its distribution and abundance is limited. S. olivacea rarely grows to the minimum legal size of 15cm carapace width (CW; carapace width is measured laterally across the carapace, between the first [most external] spine on either side). Given these factors, commercial, recreational and indigenous fishers rarely harvest S. olivacea. All references to mud crab throughout this report refer to the primary component of the catch, S. serrata. Distribution S. serrata is widely distributed throughout the IWP, from Japan across the Asian sub-continent to northern Australia, and from the east coast of Africa across to Tahiti. In Australia, mud crabs are found from Shark Bay in Western Australia, along the northern coastline and south to northern New South Wales. The entire Queensland coastline, both the along east coast and in the Gulf, is inhabited by S. serrata. Recent genetic research by David Gopurenko, a PhD candidate at Griffith University in Brisbane, is shedding new light on regional patterns of genetic structure among Australian mud crab populations. Based on investigations of the mitochondrial DNA signatures of S. serrata, Gopurenko et al. (1999) and Gopurenko and Hughes (2002) have identified two clades of S. serrata within Australian populations of the species. A clade is generally defined as a reproductively distinct group within which all individuals are derived from a common ancestor. The two clades appear to be geographically separated either side of the Torres Strait: one clade is distributed westward from the Torres Strait along the northern Australian coastline; the other clade is distributed along the eastern Australian coastline. Fishery Area The Queensland mud crab fishery occurs in all waters adjacent to the State of Queensland, including the waters of the east coast of Queensland and waters of the Gulf of Carpentaria (Map 1). As of April 1999, waters of the Torres Strait were excluded from Queensland jurisdiction and managed collectively, by the Commonwealth, the State of Queensland and Torres Strait Island Communities through the Protected Zone Joint Authority. In the Gladstone region, Eurimbula Creek (north of Round Hill Creek) and all adjoining waterways are closed to the harvesting of mud crabs. Additionally, some areas of the fishery are subject to closures to fishing

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through marine park zoning established under the Commonwealth Great Barrier Reef Marine Park Act 1975 and the Queensland Marine Parks Act 1982.

Map 1. Boundary of the Queensland mud crab fishery.

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Biology and Ecology The information contained in this section is sourced from Gribble, Brown and Williams (2002). Mature crabs mate when the female is in the soft-shell condition, which is about 48 hours after moulting. The female may remain under the protection of the male, usually in the shelter of burrows, for several days until her new shell has become hard. Sperm is stored until the eggs are extruded, and can remain viable for up to seven months. Multiple spawning in the one season may follow a single mating, and each egg mass may contain from two to eight million eggs, depending upon the size of the female. Embryonic development within the egg takes from two to four weeks, depending on water temperature. Egg-bearing females are rarely seen as they migrate to deep waters offshore to spawn. After hatching, the larvae progress through four pelagic stages during the next two weeks, drift inshore via currents, and transform into a semi-pelagic state before settling onto suitable substrate in shallow water. After 5–12 days they metamorphose into juvenile crabs. As with other crustaceans, growth occurs through moulting. This involves the shedding of the hard shell, and then swelling of soft body tissues to expand the new soft shell before it hardens. In Moreton Bay, mud crabs grow to 8–10 cm carapace width (CW) in their first year, 13–16 cm CW in their second year and (potentially) 24 cm in their third year. This growth rate appears to be accelerated in warmer northern and Gulf waters. Growth is seasonal, with moulting activity mainly from September to January. Brown (1993), summarised a number of studies on mud crab growth and sexual maturity from a variety of latitudes, and found a considerable degree of variation in both age and size at which mud crabs reach maturity. Sexual maturity has been observed to occur between 12-18 months and 9.0 – 10.0cm in tropical latitides (e.g. Philippines, Malaysia, PNG) while in sub-tropical latitudes such as south-east Queensland maturity has been estimated to occur at approximately 13.8cm and up to 27 months (Heasmann 1980). Mud crabs live for up to 3–4 years and can reach a CW of 24 cm. Mud crabs are omnivorous scavengers and are cannibalistic, eating other crabs, barnacles, bivalve molluscs and moribund or dead fish. The larger claw is often used for crushing shellfish such as mussels, whereas the other is used for biting, cutting and manipulating the food. Mud crabs usually remain in the protection of burrows during the day and feed at night, in the early evening and just before dawn. Juveniles and adults use the same habitat within sheltered estuaries, the tidal reaches of mangrove-lined rivers and streams, mud flats and mangrove forests. Strengths in the mud-crab life cycle that give high resilience to fishing pressure, include very high fecundity, protracted spawning period, rapid growth and early sexual maturation. Weaknesses of the life cycle include dependence of juveniles upon the availability and quality of appropriate near-shore habitat and the requirement for significant spawning migration by egg-bearing females, potentially increasing vulnerability to fishing activity.

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Fishing Gear and Methods Crab pots and collapsible traps are the main fishing apparatus used by commercial fishers to take mud crabs. Recreational fishers use similar apparatus to commercial fishers but are also permitted to use dillies. Under the Fisheries Regulation 1995:

• A crab pot defined as ‘a fishing apparatus comprising a cage with a round opening in the top, or an elongated opening (parallel to the base) in the side’;

• A collapsible trap is defined as ‘a trap made of rigid material, with 1 or more collapsible sides’;

• A dilly is a ‘fishing apparatus comprising a frame and a net that hangs below the frame’s horizontal plane when the apparatus is in use’; and

• An inverted dilly is defined as ‘a fishing apparatus comprising a frame and a net with a float attached so the net is above the frame’s horizontal plane when the apparatus is in use’.

The steel mesh/wire pots common up until the late 1980’s are gradually being replaced in both the commercial and recreational fisheries by more collapsible apparatus. The three pots illustrated below (Figure 1) are those commonly used by commercial and recreational fishers. The size and shape of the pots vary, though most have two entrance funnels and are cylindrical in shape. An example of the dillies commonly used by recreational mud crab fishers is also provided (Figure 1, bottom right).

Figure 1. The various apparatus used by commercial and recreational fishers in the Queensland mud crab fishery. When fishing for mud crabs the general idea is to entice the mud crabs into the pots, traps or dillies by placing bait inside the apparatus. The most common baits used include fish and fish frames, however other meat and bones are also used. Both

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commercial and recreational mud crab fishers employ a similar technique when fishing with pots or traps. Pots are set on the substrate, generally in estuarine or near-shore coastal areas, and are checked daily or on each rising tide. The pots are hauled by hand to a dinghy or small boat, checked for mud crabs, rebaited, and then reset. When checking for mud crabs, the management arrangements for the Queensland mud crab fishery require that all undersize and female mud crabs are immediately returned to the water at the point of capture. Recreational fishers using dillies lower the baited dilly to the substrate, mud crabs crawl into the net after the bait, then the whole net is lifted up, the crab is removed, and the net is again lowered into the water for another capture. The Commercial Fishery To engage in commercial harvesting in Queensland a person must hold a Queensland Master Fisher’s Licence and the vessel from which the operation is undertaken must be licensed as a Queensland Primary Commercial Fishing Vessel (CFV) with the licence endorsed to operate in the particular fishery. In the mud crab fishery, the required symbol is known as a ‘C1’ symbol. There are currently 794 vessels with a ‘C1’ symbol to take crabs. However, less than two-thirds of those vessels actually harvested mud crabs during 2001 (see Table 1). Limited entry arrangements commenced in 1984 for the mud crab fishery. Under the limited entry arrangements no new vessel licences are being issued. The only way to enter the fishery for a commercial purpose is to acquire an existing licensed vessel and engage a Master Fisher to operate it. All commercial fishers in Queensland have a legal obligation to provide information about their fishing activity through the use of compulsory daily logbooks. This information is compiled in QFS’ CFISH system - the Commercial Fisheries Information System, which commenced in 1988. It is important to recognise that the accuracy and reliability of data from the first year of the program (1988) may be uncertain due to ‘teething problems’ in launching CFISH. For the mud crab fishery, the data commercial fishers provide to CFISH via the logbook program must include a daily record of the location fished, an estimate of mud crab caught (in kg), an estimate of other crab species caught (excepting spanner crab which is prohibited), the total number of pots used, the total number of pot lifts, and any interactions with threatened or protected species (Gribble, Brown & Williams 2002). The reporting of interactions with threatened or protected species is currently being enhanced through an amended logbook. A summary of annual statistics for the Queensland mud crab fishery is provided in Table 1. Statewide, the numbers of boats reporting harvest has oscillated significantly, though a general upward trend is apparent. The days fished per boat exhibits a similar pattern – some oscillation with a general upward trend. Accordingly, the total effort of the commercial sector, measured as total boat days fished, has increased though the trend has been variable. Total effort increased significantly during the periods 1992-1993 and 1996-2000. However, over the past two years (2001 and 2002) total effort has again decreased such that the 2002 total effort was back to the 1999 level. Commercial harvest trends have been generally upward with the highest reported catch of about 1000 tonnes in 2000. The current total catch (2002) is approximately

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equivalent to the 1999 total catch. Mean annual CPUE, measured as daily boat harvest (kg/day), averaged about 21 kg with no substantial upward or downward trend, although there is some variation. The period 1993-1997 was below the mean daily catch rate, while the year 1990 and the period 1999-2002 were above the mean. The top 10% of the fleet, about 50 boats, landed 50% of the harvest and applied 35% of the effort in terms of days fished. These boats typically worked for 160 days per year with a daily harvest of about 30kg. Table 1. Annual statistics for the Queensland mud crab fishery

Year Boats Catch (t) Days fished Days/boat Kg/day 1988 374 280 13900 37 20 1989 409 377 18550 45 20 1990 361 416 18561 51 22 1991 391 397 19578 50 20 1992 373 434 21354 57 20 1993 444 466 25344 57 18 1994 431 449 24133 56 19 1995 440 454 24829 56 18 1996 470 535 27405 58 20 1997 517 594 31482 61 19 1998 489 674 32771 67 21 1999 518 831 37625 73 22 2000 513 1000 39848 78 25 2001 533 987 38626 72 26 2002 468 808 37484 80 22

The aggregated statewide data can also be analysed at a finer spatial scale. Williams (2002) divided the Queensland coastline into eight regions, to allow regional analysis of CFISH data (see Map 2). Although mud crabs are harvested from estuaries along the entire Queensland coast, approximately 70% of the catch is harvested from three regions. Based on 2001 data, the Capricorn region accounts for approximately 42% of the total catch, the Gulf region approximately 16%, and the Northern Dry region approximately 12% (see Table 2). Table 2. Breakdown of catch data for the eight CFISH regions (based on the 2001 fishing season). Location Catch (t) Proportion of

Catch (%) Gulf Remote Northern Wet Northern Dry Swains Capricorn Fraser Burnett Moreton

154 37 71

119 25

411 78 91

16 4 7 12 3 42 8 9

State total 987

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Map 2. The eight CFISH regions based on Williams (2002) The Recreational Fishery Mud crabs are also a popular target species for recreational fishers. QFS undertakes a biennial estimate of the recreational catch of mud crab in Queensland through telephone and diary surveys conducted under RFISH – the Recreational Fishing Information System. RFISH surveys have been conducted in 1997, 1999 and 2002. The 1997 RFISH survey estimated that approximately 700 000 mud crabs were harvested by recreational fishers in that year. The 1999 RFISH survey estimated that approximately one million mud crabs were harvested while a further 2.5 million mud crabs were caught and released. The average mud crab weight of the recreational harvest has not yet been estimated however Gribble, Williams and Brown (2002) suggest that the commercial average weight of 1kg per crab can be used without

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significant error since the same size restrictions apply to both commercial and recreational fishers. Accordingly, the recreational harvest of mud crabs throughout Queensland is estimated at 600-700 tonnes in 1997 and 900-1100 tonnes in 1999. Gribble, Williams and Brown (2002, p126) state that the recreational catch “…was distributed along the eastern coast of Queensland with similar regional patterns to those of the commercial sector, apart from the Moreton region. It is estimated that the Moreton region recreational harvest was about 260 tonnes in 1997 and 1999”. The Indigenous Fishery The catch of mud crabs in Queensland by indigenous fishers and communities in north Queensland is currently being estimated as part of the National Recreational and Indigenous Fishing Survey (NRIFS) funded by the Fisheries Research and Development Corporation (FRDC) and the Natural Heritage Trust (NHT)(Johns 2000). The results will be available with the release of the final NRIFS report in mid- to late-2003 (J. Higgs, QFS, pers. comm., 2003). Historical Management of the Fishery Crabs comprised an important dietary component for aboriginal communities along the Queensland coast before and after European habitation. The earliest records of European involvement in the crab fishery date back to the establishment of the penal settlement on the shores of Moreton Bay in the 1820’s. Convicts caught crabs along with other marine animals to supplement food production in the settlement. The subsistence harvesting of crabs soon developed into small-scale commercial operations during the latter part of the 19th century, first in Moreton Bay and then beyond, to cater for the needs of Queensland’s expanding population. By the turn of the century a recognised crab fishery had emerged. A range of management measures has evolved over the life of the mud crab fishery to provide restraints on fishing effort and to ensure sustainable management of the mud crab resource and its habitat. A timeline of the history of the fishery and the management arrangements introduced is provided in Table 3. Table 3. Queensland mud crab fishery: history and management arrangements.

Time Frame Historical Management Pre-European settlement

• Aboriginal communities harvested mud crabs for subsistence needs.

1820’s • Convicts caught crabs on the shores of Moreton Bay along with other marine animals to supplement food production.

Late 1800’s 1890’s Early 1900’s

• Small-scale commercial operations were established to cater for the needs of Queensland’s expanding population.

• Growth extended beyond Moreton Bay to population centres along the coast.

• Minimum weight restrictions were introduced: 3 pounds (~ 1.4 kg) for

male mud crabs and 10 pounds (~ 4.5 kg) for female mud crabs. • A recognised mud crab fishery emerged.

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1913 • Harvesting female mud crabs was prohibited (this restriction continues to apply).

• The minimum weight restriction for male mud crabs was converted to a minimum size limitation: 5 inches (12.5cm) carapace width (CW).

1927 • The minimum ‘size’ for male mud crabs was increased to 6 inches (15cm) CW (this restriction continues to apply).

1976

• Where the carapace of a crab is damaged alternative underside measurements must be used: 4.6cm from joint of the claw to the joint of the last walking leg (this restriction continues to apply).

• The possession of crab meat and claws separate from carapace was prohibited

1984 • Limited entry arrangements were introduced into the commercial mud crab fishery.

• Gear and in possession limits were implemented in the recreational fishery: a maximum of four apparatus and an in possession limit of 10 legal size male crabs.

1991 • A limit of fifty crab pots was introduced for each commercial fishing operation. Previously this limit applied to each licensed master fisherman involved in the operation (this restriction continues to apply).

Current Management Arrangements The Queensland Fisheries Service (QFS) in the Queensland Department of Primary Industries (QDPI) is responsible for managing the Queensland mud crab fishery. Queensland Boating and Fisheries Patrol, a part of QFS, undertakes compliance and enforcement. Research and monitoring of the fishery is conducted jointly by QFS and QDPI’s Agency for Food and Fibre Sciences (AFFS). QFS manages the mud crab fishery under the Fisheries Act 1994 (the Act) and the Fisheries Regulation 1995. Some areas of the fishery are also subject to marine park zoning established under the Commonwealth Great Barrier Reef Marine Park Act 1975 and the Queensland Marine Parks Act 1982. As outlined in the previous section, a number of input and output controls have been developed over the history of the fishery to ensure it is sustainably managed over the long-term. A complete list of the current management controls in place in the fishery is provided in Table 4. If threats to the sustainability of the fishery are identified, QFS has various mechanisms available under the Act to respond in a timely manner. These include the power to:

a) declare a closed season, closed waters or closed species (section 43 of the Act); b) declare quota (section 44); c) make an emergency fisheries declaration (section 46) where urgent action is

needed to meet a significant threat to fisheries resources or habitat; d) refuse to issue or renew an authority (section 59) where it is necessary or

desirable for the best management or protection of fisheries resources; e) impose conditions on issue or renewal of an authority (section 61); f) amend an authority (section 63); and g) suspend or cancel an authority (section 67) where it is necessary or desirable for

the best management, use, development or protection of fisheries resources or fish habitats.

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Table 4. Summary of the current management arrangements for mud crabs Management arrangement Commercial fishery Recreational fishery Number of Fishers Limited Entry Unlimited Taking female crabs Prohibited Prohibited Minimum size limit 15cm carapace width 15cm carapace width In possession limit N/A Not more than 10 per

person No. of apparatus Not more than 50 per

crab fishery symbol Not more than 4 per person

Apparatus marking Owner’s name or primary commercial fishing boat marking

Owner’s surname and address

Float marking Owner’s primary commercial fishing boat marking

Owner’s address

Float size 15cm in any dimension 15cm in any dimension Age limit on using crab apparatus

N/A Must be 15 yrs or over

Use of crab hooks Prohibited Prohibited Possession of crab meat Prohibited Prohibited Possession of crab claws separate from body

Prohibited Prohibited

A range of enforcement and compliance measures are in place in the fishery. One aspect of compliance in the fishery concerns the compulsory return of daily logbook information. For non-quota fisheries such as the mud crab fishery, the daily logbook records must be returned to QFS on a monthly basis. If a fisher does not return the logbook data, the following steps are followed:

• a reminder letter is sent requesting the logbook, and also reminding the fisher of the compulsory logbook requirement;

• approximately one month later a ‘show cause’ letter is sent. The letter again requests the logbook and also asks the fisher to show cause why the non-compliance should not result in suspension of the fisher’s license for that fishery.

• if the logbook is still not forwarded, the fisher’s licence for the fishery may be suspended until the logbook is provided.

The Fisheries Act 1994 (‘the Act’) defines ‘an offence against fisheries legislation prescribed under a regulation or Management Plan to be a serious fisheries offence’. In effect, the Act enables offence types common to many fisheries to be covered by regulation, and significant offences may be addressed within a management plan for that fishery. Section 108 of the Fisheries Regulation 1995 establishes serious fisheries offences as:

• Forfeiture offences for which an inspector may seize fisheries resources in a heap (for example, fish in a processing establishment where, because of the quantity of fish, it is impracticable to count the fish of a particular species or type);

• Offences against fisheries regulation that involve: - contravening a closed season or closed-water declaration;

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- buying or selling fish; - obstructing, hindering or resisting an inspector; and - using or possessing illegal fishing apparatus.

A ‘serious’ offence can have several consequences. The most obvious is in the penalties applied to offenders. Magistrates have full discretion in setting penalties for fisheries offences up to a maximum level for each offence. If an offence is identified as ‘serious’, then it is likely that a higher-level fine would be applied. The management arrangements for the mud crab fishery have been developed over several years through a formal and statutory public consultative process involving a Management Advisory Committee, CrabMAC, and public comment and input. The Management Advisory Committee provides advice and recommendations on the appropriate management arrangements to ensure the sustainable use of the mud crab resource. CrabMAC includes representatives with a range of expertise and representing broad community interests. The stakeholders currently represented on CrabMAC are listed in Table 5. It should be noted that the conservation member position is currently vacant, though it has been filled previously. QFS has approached environmental organisations to fill the position however these efforts have been unsuccessful to date. Table 5. Current CrabMAC stakeholder membership

Stakeholder Interest DPI Appointed Chair

Research Member (QDPI – AFFS) Recreational Fisher

QFS Fishery Manager Qld Boating & Fisheries Patrol (QBFP)

Commercial Fisher Commercial fisher Recreational fisher Seafood Marketing Commercial Fisher

Great Barrier Reef Marine Park Authority (GBRMPA) In 1999, the then fishery management agency, the Queensland Fisheries Management Authority (QFMA), released the ‘Discussion Paper - Queensland Mud Crab Fishery’ (QFMA 1999) seeking public comment and input on an extensive range of issues facing the fishery (see Appendix 3 for a complete list of the issues raised for public comment). Primary among these issues was the separation of the Gulf and the East Coast mud crab fisheries. The Discussion Paper sought comment on the development of separate fishing symbols, management arrangements and management plans for the Gulf and the East Coast. Previous to the Discussion Paper, QFS, with the full support of CrabMAC, had indicated its intent to develop separate management arrangements for the Gulf through the ‘1997 Investment Warning for the Gulf of Carpentaria Mud Crab Fishery’ (QFMA 1999). The investment warning advised all interested parties that “…investment and catches after the date of [the] warning [were] extremely unlikely to be recognised in determining eligibilities for future participation in the [Gulf] fishery” (QFS media release, cited in QFMA 1999).

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The release of the Discussion Paper was the first step in developing a formal Management Plan for the fishery. QFMA distributed approximately 2800 copies of the Discussion Paper to stakeholders and groups directly and indirectly involved in the fishery. A significant level of public response was received, comprised of:

• 24 responses from organisations/groups/branches; • 82 responses from commercial fishers; • 123 responses from recreational fishers; • 1 response from an indigenous fisher; and, • 9 responses from ‘other’ stakeholders.

QFMA collated and analysed the responses. CrabMAC also analysed the responses and provided comments and recommendations. The development of the Mud Crab Fishery Management Plan is awaiting the implementation of management plans currently ‘in-progress’ for other fisheries (Mark Doohan, Fishery Manager, QFS, pers. comm., 2003). Environmental Impacts of the Fishery At current levels of effort, utilising current fishing gear and methods, and under current management arrangements, QFS considers the Queensland mud crab fishery does not pose any significant threat to dependent and associated species; endangered, threatened or protected species; or the broader marine ecosystem generally. Mud crab pots are generally constructed of wire mesh though hard plastic and trawl mesh pots are also used in the recreational fishery, as are mesh dillies (see Figure 1). These apparatus are relatively lightweight and stable and therefore impart little physical impact to the muddy substrates of the estuaries or foreshore areas in which they are set. Daily pot checks and frequent pot repositioning, which is the standard practice in both the commercial and recreational fisheries, further reduces the potential for long-term impacts to benthic habitats and communities, or to water quality in general. Mud crab pots are also a non-destructive fishing apparatus as they function by trapping; crabs are enticed into the pots with bait and their escape is restricted. Considered in combination with the general practice of daily pot checking, mud crab pots impart little physical damage to either mud crabs or any bycatch that is caught. This is an important factor as it results in high survivability in undersize and female mud crabs, and bycatch species, that are released. All available evidence suggests that the take of non-target bycatch species in the Queensland mud crab fishery is minimal. Preliminary results on non-target catch obtained by QFS through fishery-independent surveys conducted in the Long-Term Monitoring Program indicate an average non-target CPUE of approximately one individual every three to four pot lifts (Sue Helmke, QFS, pers. comm. 2002). The preliminary bycatch results obtained in the NTDBIRD-FRDC-QDPI Mud Crab Project support these general observations (Steve Bailey, AFFS pers. comm. 2002). Anecdotal evidence from researchers and fishers in both Queensland and the Northern Territory confirms that minimal non-target catch is taken.

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Concerning byproduct from the mud crab fishery, very little of the non-target catch that is taken is considered useful or desirable as byproduct. Comments from QDPI researchers with experience in the mud crab fishery indicate that commercial fishers opportunistically use some larger fish, particularly cod and catfish, as bait for crab pots (Steve Bailey, AFFS, pers. comm., 2002; Stirling Peverell, QFS, pers. comm., 2002). Mud crab fishers may legally retain blue swimmer crabs for sale as byproduct. However, the byproduct catch of blue swimmer crabs is not considered a significant risk to populations of that species since mud crabs and blue swimmer crabs generally do not occur in the same habitats. Research and Monitoring Program At present, a large part of QFS’s research and monitoring focus concerning the mud crab fishery is focussed on two major projects: the Long-Term Monitoring Program (LTMP); and the habitat mapping and stock abundance estimation being pursued through the NTDBIRD-FRDC-QDPI Mud Crab Project. The Long-Term Monitoring Program (LTMP) was initiated in 1999 to collect information about the status of fish stocks and key habitats and to monitor major fishery species over many years. The project has ongoing funding as it is recognised that the power is not in any individual year’s data but in the long-term time-series that will develop as monitoring continues (Helmke et al. 2002). Each crab caught is identified (to the species level), measured, sexed, eggs are recorded for females (if present) and the presence of any parasites or abnormal features is also noted. As of 2002, all bycatch species are identified and recorded. Water quality is also measured annually at each site and a detailed survey of habitat characteristics is carried out every three to four years (Helmke et al. 2002). The LTMP surveys are not intended to produce an estimate of total biomass or crab density, or to fulfil the role of a formal stock assessment. Rather, the time-series of data as it develops will provide a range of independent checks on fishery-dependent measures of change in the stock from year to year. To illustrate, catch and effort statistics recorded in the LTMP will allow an estimate of annual changes in relative abundance (statewide and at a regional level). Similarly, length and sex information will allow long-term comparison of changes in population structure. Data on habitat and water quality will allow QFS to detect changes that may affect the mud crab resource (Helmke et al. 2002). The recent inclusion of bycatch recording in the LTMP enhances QFS’ ability to monitor the impacts of the mud crab fishery on the wider marine environment. LTMP status reports are produced biennially to analyse the data obtained and summarise the changes to the mud crab stock and habitat. The next status report is due in 2003. The results of the mud crab component of the LTMP are presented annually to CrabMAC. The NTDBIRD-FRDC-QDPI Mud Crab Project represents phase one of the three-phase ‘Five-year Research Strategy for Northern Australian Mud Crab Resources’ endorsed by Queensland, Northern Territory and Western Australian fisheries managers at the 1999 National Mud Crab Workshop (Calogeras 2000). The project addresses phase one of the research plan, through the following two objectives:

1. Identifying and quantifying critical mud crab habitat using remote sensing techniques; and

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2. Estimating the corresponding mud crab abundance per unit of habitat using novel mark-recapture and depletion techniques (Hay and Phelan 2002).

In addition to its main objectives, the project is also producing valuable initial bycatch results, and may provide some information on the impacts of the adult mud crab catch on the ecosystem generally (NTDBIRD 2002). A comparative assessment of fished and unfished areas, suggested by the Northern Territory as an extension to the project subject to available resources (NTDBIRD 2002), may provide more detailed ecosystem information. Marketing Mud crabs are sold into local and interstate markets and are a particularly important “icon” species to the tourist and hospitality trade. There is a small live export trade to Asia from northern Queensland centres. The dominant product form is whole crab, live or chilled. There is competition from interstate product, especially from the Northern Territory where both males and females can be sold at smaller sizes. Prices paid to fishers are consistent at about $8 – 12 per kilogram (Lee 2002).

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PRINCIPLE 1. A fishery must be conducted in a manner that does not lead to over-fishing, or for those stocks that are overfished, the fishery must be conducted such that there is a high degree of probability the stock(s) will recover. Objective 1. The fishery shall be conducted at catch levels that maintain

ecologically viable stock levels at an agreed point or range, with acceptable levels of probability.

Information requirements 1.1.1 There is a reliable information collection system in place appropriate to the

scale of the fishery. The level of data collection should be based upon an appropriate mix of fishery independent and dependent research and monitoring.

Both fishery-dependent and fishery-independent information is collected for the Queensland mud crab fishery. This information enables stock assessment of the fishery and helps to ensure that catch and effort levels, and fishing gear and methods are all managed for sustainability. Fishery-dependent data from the commercial sector of the fishery is collected via CFISH – the Commercial Fisheries Information System. Since its commencement in 1988, CFISH has collected daily data from commercial fishers about their commercial fishing activity through the use of compulsory logbooks. Two different logbooks are used in the Queensland mud crab fishery: fishers in the Gulf of Carpentaria use the Gulf Set Net Fishery logbook (see Appendix 1) and fishers along the east coast use the East Coast Net and Crab Fishery logbook (see Appendix 2). The example logbook pages reveal that identical information is collected in the Gulf and along the East Coast. All commercial fishers in Queensland have a legal obligation to provide information about their fishing activity. Section 118 of the Fisheries Act 1994 (the Act) and Section 109(1)(b) of the Fisheries Regulation 1995 (the Regulation) require that all holders of primary commercial fishing boat licences and holders of authorities to take, possess or sell fish must keep detailed statistical records about their fishing activities and provide such records to QFS. Section 118 of the Act clearly outlines that any person who fails to comply with an obligation to keep and provide the logbook or other information about fisheries required by QFS is liable to prosecution for an offence against the Act. For the mud crab fishery, the data provided to CFISH via the logbook program must include a daily record of the location fished, an estimate of the weight of mud crab caught (in kg), an estimate of other crab species caught (excepting spanner crab which is prohibited), the total number of pots used, the total number of pot lifts, and any interactions with threatened or protected species (Williams 2002). The reporting of interactions with threatened or protected species is currently being enhanced through the development of a new logbook. During 2003 all license holders will be issued with a new ‘Species of Conservation Interest logbook’ (SOCI01). With this logbook

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fishers will be able to differentiate the particular activity that caused the interaction – for example netting, mud crab potting, etc. (Shane Gaddes, QFS, pers. comm., 2002). At present, no formal procedures exist to verify the accuracy of data provided by commercial fishers in the daily logbook returns. In light of this absence, QFS is currently in the process of designing and implementing a generic ‘buyers returns logbook’. Although still in the preliminary stage, QFS envisages that the logbook will apply to all species under quota management and other species for which QFS considers catch data verification to be a high priority (Jim Higgs, QFS, pers. comm., 2003). The CFISH logbook data is one of the primary bases for the stock assessments and analyses that QFS conducts on the mud crab fishery. More information on these assessments and analyses is provided in criteria 1.1.2. Information on the recreational catch and effort in the mud crab fishery is sourced from RFISH – the Recreational Fishing Information System. RFISH was developed in the mid-1990s following recognition that QFS required greater information on the activities of recreational fishers to ensure that fish stocks and fisheries are sustainably managed. Prior to RFISH, accurate timely estimates of even basic information such as the recreational fish catch and fishing effort was difficult to obtain. Confounding factors included the large number of anglers, their ability to fish from a wide range of environments, and the lack of legislative requirements for anglers to provide information on their fishing activities (Williams 2002). RFISH is based on a biennial two-stage survey using a statewide telephone survey and a 12-month diary program. The telephone survey is used to estimate the number of residents that fish, statewide and on a regional basis. The telephone survey is also used to identify recreational fishers willing to maintain a diary of their fishing activities for the following 12 months. Approximately 5000 fishers are usually involved in the diary program (5022 in 1997, 4506 in 1999). However, volunteer logbook programs such as the RFISH diaries typically suffer a considerable attrition rate (Bradford 1998, cited in Higgs 1999). In 1997, 3440 fishers completed the diary program (Higgs 1999) while in 1999, 3031 fishers did so (Higgs 2001). To assess the representativeness of the sample size, the total Queensland recreational fishing population (>15 years of age) was 667 600 in 1997 and 639 800 in 1999. The diaries allow an estimate of the catch of recreational species and species groups, including mud crabs. Again, these estimates are available statewide and on a regional basis (Higgs 2001). QFS has now conducted three RFISH surveys – 1997, 1999 and 2002. The results of both the 1997 (Higgs 1999) and 1999 (Higgs 2001) surveys are fully published and the 2002 survey results will be published by late-2003 (Jim Higgs, QFS, pers. comm., 2002). QFS staff have continued to refine the RFISH survey methodology and parameters since the inception of the program in 1997. To illustrate these refinements concerning the mud crab fishery, the 1997 survey provided a single aggregated estimate for all crabs species caught whereas the 1999 and 2002 surveys provide an individual estimate of the mud crab catch. A second major refinement still being concluded concerns the conversion of catch estimates from abundance (e.g. the number of individuals) to weight (e.g. tonnage). This refinement is particularly important as it will allow the inclusion of the recreational catch estimates provided

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through RFISH with the commercial catch estimates provided through CFISH in future stock assessments (Higgs 2001). With three recreational fishing surveys completed, Queensland has the most advanced ongoing assessment of statewide recreational fish catch of any state in Australia. Queensland is also heavily involved in the National Recreational and Indigenous Fishing Survey (NRIFS). The NRIFS was conducted over the 12-month period from May 2000 to April 2001 (Higgs 2001). The final project report is due mid- to late-2003. Since the NRIFS utilized a somewhat different survey methodology to that used in RFISH, comparison of the methodologies and estimates provided by each should enhance the process to estimate recreational catch and ultimately yield a more accurate assessment of recreational catch. The NRIFS will also provide a first estimate of the indigenous and international visitor catch of a number of prominent species, including mud crabs. Current advice indicates that the results of the indigenous component of the NRIFS will be available when the final NRIFS report is released mid- to late-2003 (J. Higgs, QFS, pers. comm., 2003). The Queensland Department of Primary Industries (QDPI) has an extensive fishery-independent information base on the Queensland mud crab fishery, compiled over the past twenty-five years. This information base is a result of research conducted by QDPI, and by external researchers, and includes:

• Aspects of the general biology and fishery of the mud crab (1976-80) • Methods for determining the size and sex of marketed mud crabs • Queensland mud crab fishery (1979-82) • Genetic relationship and identification of mud crabs from the Indo-Pacific

region (1996-98) • Mud crab ‘rust spot’ shell disease (1998-2001) • Genetic analysis of Indo-Pacific mud crab stocks (ongoing)

In addition to the above research and monitoring projects, QDPI has three research programs that focus on mud crab stocks. These programs are the primary sources of current information on the Queensland mud crab fishery:

a) QFS Long-Term Monitoring Program (LTMP). b) Northern Territory Department of Business, Industry and Resource

Development (NTDBIRD) and Fisheries Research and Development Corporation (FRDC) and QDPI Mud Crab Project.

c) QDPI Tropical Resource Assessment Program (TRAP). a) In 1999, the Long-Term Monitoring Program (LTMP) was initiated to collect information about the status of fish stocks and key habitats and to monitor major fishery species over many years. The project has ongoing funding as it is recognised that the power is not in any individual year’s data but in the long-term time-series that will develop as monitoring continues (Helmke et al. 2002). The mud crab component of the LTMP annually surveys sixteen river systems throughout the entire Queensland coastline (Map 3). Each river system is divided into four sites, which correspond to the major habitat areas within the system: foreshore, mouth, mid-estuarine and upper estuarine. This sub-division ensures that the sampling

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program provides good coverage of the major areas within each river system and a reasonable coverage of crab size classes (Helmke et al. 2002). Twenty baited pots are set at each of the four sites, with each pot hauled just once. The fishing gear and methods are similar to those used by commercial operators, within certain logistic limitations. For a detailed explanation of the sampling gear and methodology see Helmke and Gribble (2002).

Map 3. River system sampled in the Long-Term Monitoring Program – Mud Crab

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Each crab caught is identified (to the species level), measured, sexed, the presence of eggs is recorded for females and the presence of any parasites or abnormal features is also noted. Beginning with the 2002 surveys, all bycatch species are identified and recorded. Water quality is also measured annually at each site and a detailed survey of habitat characteristics is carried out every three to four years (Helmke et al. 2002). It is important to note that the LTMP surveys are not intended to produce an estimate of total biomass or crab density, or to fulfil the role of quantitative stock assessment. Rather, the time-series of data as it develops will provide a range of independent checks on changes in the stock from year to year. To illustrate, catch and effort statistics recorded in the LTMP will allow an estimate of annual changes in relative abundance (statewide and at a regional level). Similarly, length and sex information will allow long-term comparison of changes in population structure. Data on habitat and water quality will allow QFS to detect changes that may affect the mud crab resource (Helmke et al. 2002). The recent inclusion of bycatch recording in the LTMP enhances QFS’ ability to monitor the impacts of the mud crab fishery on the wider marine environment. LTMP status reports are produced biennially to analyse the data obtained and to summarise the changes to the mud crab stock and habitat. The next status report is due in 2003. The results of the mud crab component of the LTMP are presented annually to CrabMAC. Incorporating the results of the LTMP into the MAC process enhances CrabMAC’s ability to ensure that Queensland’s mud crab resources are managed sustainably, both in the short- and long-term. As the LTMP began in 1999, it is still too early to speculate on any trends apparent in the results to date. Accordingly, CrabMAC has not produced any definitive responses in the management arrangements directly related to LTMP results. As the time-series of LTMP data lengthens, QFS envisages that such a situation will develop. b) Northern Territory Department of Business, Industry and Resource Development (NTDBIRD), Fisheries Research and Development Corporation (FRDC) and QDPI currently have a collaborative research project underway on northern Australian mud crab abundance and habitat (hereafter referred to as the NTDBIRD-FRDC-QDPI Mud Crab Project). The project was initiated following the 1999 ‘National Mud Crab Workshop’ (Calogeras 2000). Participants at the workshop including researchers and managers from Queensland, Northern Territory and Western Australia, and Northern Territory industry representatives, developed a ‘Five-Year Research Strategy for Australian Mud Crabs’. NSW Fisheries, though not a participant at the workshop, also endorsed the research plan. The aim is to maximise the total research productivity for the Australian mud crab resource by eliminating the replication of research in each state. The research plan consists of a coordinated three-phase approach to:

1. examine the relative productivity of mud crab habitats; 2. compare stock abundance indicators; and 3. investigate the spatial differences in population reproductive characteristics

(Hay and Phelan 2002). The current NTDBIRD-FRDC-QDPI Mud Crab Project addresses phase one of the research plan, through the following two objectives:

1. Identifying and quantifying critical mud crab habitat using remote sensing techniques; and

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2. Estimating the corresponding mud crab abundance per unit of habitat using novel mark-recapture and depletion techniques (Hay and Phelan 2002).

One component of QDPI’s involvement in the project concerned the habitat-mapping element outlined in objective one. This objective was fully completed during 2002 (see de Vries et al. 2002; Hay and Phelan 2002). Regarding objective two, both NTDBIRD and QDPI Northern Fisheries Centre have completed the assessment of techniques for estimating the abundance of mud crabs in two different habitat types. A depletion-mark recapture sampling design is recommended for mangrove-lined streams while a trapping web design is recommended for foreshore mudflat areas (Hay and Phelan 2002). Completing the second objective and producing an estimate of mud crab abundance per habitat is ongoing. As at December 2002, both NTDBIRD and QDPI Northern Fisheries Centre had completed the majority of the in-field sampling with validation and analysis of the data continuing. Some preliminary results and greater detail on the project in general are available in the 2002 FRDC project progress report (Hay and Phelan 2002). The project is due to be completed in June 2004. c) In 1995, the Tropical Resource Assessment Program (TRAP – Phase One) was initiated by QDPI, in conjunction with FRDC, to develop models describing stock dynamics and exploitation in North Queensland fisheries. The first phase of TRAP was concluded in 1999 with a final Technical Report released soon after (Gribble 1999). Within TRAP (Phase One), mud crab and barramundi were the two priority species upon which research was focussed. Accordingly, a number of objectives were proposed within TRAP (Phase One) specific to the mud crab resource. The final Technical Report for TRAP (Phase One) outlined that the following objectives had been achieved concerning the mud crab fishery:

1. Collated and analysed historical research and logbook statistics for mud crab from both the Gulf and East Coast inshore fishery datasets. This work was the basis of three annual reports released throughout TRAP (Phase One)(see Magro et al. 1997, 1998; Hall 1999).

2. Developed a habitat-alias model for mud crab biomass estimation, incorporating satellite imagery to determine total area of mud crab habitat and either logbook or independent surveys to establish crab density estimates in particular habitats.

3. Provided stock assessment advice to CrabMAC on the status of the mud crab fishery.

4. Facilitated QDPI partnership in the 'Five-Year Research Strategy for Australian Mud Crabs’ (described in (b) above).

The habitat-alias model developed in TRAP is fundamentally the same model as that currently being used in the NTDBIRD-FRDC-QDPI Mud Crab Project. In fact, one of the first trials of the habitat-alias model for northern Australian mud crab resources arose as a spin-off project from the main TRAP (Phase One) project. The spin-off project ‘Abundance estimates for Albatross Bay, Weipa’ was a collaborative project between QDPI and the Weipa Catchment Coordinating Group funded initially by the Queensland Fisheries Management Authority (QFMA) and subsequently through Natural Heritage Trust (NHT) grants. Two project reports have been released to date (Helmke et al. 1998; Gould et al. 2001) each of which has provided a preliminary estimate of mud crab abundance for the Weipa region. A third report, with a third preliminary estimate, is expected by mid-2003.

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Assessment 1.1.2 There is a robust assessment of the dynamics and status of the species/fishery

and periodic review of the process and the data collected. Assessment should include a process to identify any reduction in biological diversity and /or reproductive capacity. Review should take place at regular intervals but at least every three years.

A meaningful estimate of the potential productivity of a fish stock and of the proportion that can be sustainably harvested requires a biologically accurate stock assessment model. No such stock assessment model or estimate of stock size is available for the Queensland mud crab fishery or for Australian mud crab fisheries generally due to the inappropriateness of traditional stock assessment methods. Therefore a novel stock assessment model and methodology has been devised and is being developed through the NTDBIRD-FRDC-QDPI Mud Crab Project (outlined above in criteria 1.1.1). Catch-effort models and assessment methods based on catch-rate data are not appropriate in northern Australian mud crab fisheries due to the non-random pattern of fishing effort. Available evidence indicates that mud crab fishers in northern Australia systematically fish then rest local areas throughout the fishing season to maintain hyperstability in catch per effort (Walters et al. 1997; Hay and Phelan 2002). Similarly, traditional length-based methods for estimating growth and mortality rates are not appropriate as mud crabs do not experience continuous body growth and therefore stocks lack discrete length cohorts (Walters et al. 1997). As with all other crustaceans, mud crabs grow by shedding their exoskeleton through periodic moults or ecdyses (Brown 1993). There is a high variance in individual growth rates (Knuckey 1999 cited in Hay and Phelan 2002). Other common assessment methods such as visual counts or trawls are also unsuitable. Visual counts cannot be conducted in the highly turbid estuaries and inshore waters that comprise mud crab habitats. Trawling cannot be conducted due to the burrowing behaviour of mud crabs and the non-selectivity of the fishing gear (Hay and Phelan 2002). In recognition of the inappropriateness of traditional methods, the Northern Territory commissioned Professor Carl Walters, of the Fisheries Centre, University of British Columbia in Canada. Professor Walters suggested a ‘habitat-alias’ stock assessment model (Walters et al. 1997). The habitat-alias method obtains an estimate of stock size based on the logic that: stock size = (mud crabs per unit habitat area) x (total habitat area). This is the basis of the NTDBIRD-FRDC-QDPI Mud Crab Project described in criteria 1.1.1. To recap the results outlined in criteria 1.1.1, at this stage (December 2002), QDPI has completed the habitat-mapping component outlined in objective one, and both NTDBIRD and QDPI are producing preliminary results for mud crab abundance experiments conducted in 2001 and 2002 (see Hay and Phelan 2002). The project is due to be completed in June 2004.

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Also mentioned in criteria 1.1.1, QDPI has trialed the ‘habitat-alias’ model in Albatross Bay in the Weipa region, Gulf of Carpentaria (Helmke et al. 1998; Gould et al. 2001). To date, the project has produced two preliminary estimates of mud crab abundance. As the ‘habitat-alias’ stock assessment model is not yet fully developed, QFS is continuing to ensure that Queensland’s mud crab harvests are sustainable through monitoring of the fishery-dependent and –independent information. “Condition and Trend Reports”, which are based primarily on fishery-dependent data (e.g. commercial logbooks, RFISH diaries), are produced regularly for all Queensland’s state-managed fisheries (see Williams 2002). These provide a current overview of statewide fish stock status, trends and management arrangements, and aim to suggest causes for any trends. The 2002 Condition and Trend Report highlighted two primary resource concerns that should be monitored in the mud crab fishery: the reduction in habitat area and quality; and the lack of understanding concerning the effects of climate on mud crab stocks. The Moreton region of the fishery was also singled out as a high priority for monitoring due to the low catch rates evident. Status Reports to CRABMAC, which incorporate both fishery-dependent and –independent information, are also produced on a need basis (for example, Gribble and Williams 2001). These reports outline commercial catch/effort trends, ongoing fishery-independent monitoring, and current research. With regards to stock assessments based on fishery-independent data, beginning in 2002 the Long-Term Monitoring Program will produce biennial status reports. Concerning the mud crab fishery, the reports will outline the condition of and changes to mud crab abundance, stock characteristics such as size and sex ratio, and habitat. The reports are based on the annual fishery-independent LTMP surveys conducted along the East Coast and in the Gulf of Carpentaria (see Helmke and Gribble 2001). These reports are presented to CrabMAC for consideration in the sustainable management of the fishery. 1.1.3 The distribution and spatial structure of the stock(s) has been established and factored into management responses. Estuarine crabs of the genus Scylla inhabit most areas of mangrove-lined coastal habitat throughout the tropical and sub-tropical Indo-West Pacific (IWP) region. A taxonomic revision of Scylla by Keenan et al. (1998) identified four distinct species. The mud crab, Scylla serrata, is the most widespread species of the genus, distributed from Japan throughout the Asian sub-continent to northern Australia, and from the east coast of Africa across to Tahiti. In Australia, mud crabs are found from Shark Bay in Western Australia, along the northern coastline and south to northern New South Wales. The entire Queensland coastline, both the along East Coast and in the Gulf, is inhabited by S. serrata. The brown mud crab, S. olivacea, is also found within Queensland waters in the northern part of the Gulf of Carpentaria however the species requires low saline estuarine habitats and therefore both its distribution and abundance is limited. In addition, S. olivacea rarely grows to the minimum legal size of 15cm CW. Given these factors, commercial, recreational and indigenous fishers rarely harvest S.

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olivacea. As stated previously, all references to mud crab throughout this paper refer to S. serrata. The Queensland mud crab fishery comprises all waters relevant to the State of Queensland, including the waters of the east coast of Queensland and waters of the Gulf of Carpentaria (see Map 1). As of April 1999, waters of the Torres Strait were excluded from Queensland jurisdiction and managed collectively, by the Commonwealth, the State of Queensland and Torres Strait Island Communities through the Protected Zone Joint Authority. Recent research by David Gopurenko, a PhD candidate at Griffith University in Brisbane, is shedding new light on regional patterns of genetic structure among Australian mud crab populations. Based on investigations of the mitochondrial DNA signatures of S. serrata, and Gopurenko and Hughes (2002) have identified two clades of S. serrata within Australian populations of the species. A clade is generally defined as a reproductively distinct group within which all individuals are derived from a common ancestor. The two clades appear to be geographically separated either side of the Torres Strait: one clade is distributed westward from the Torres Strait along the northern Australian coastline; the other clade is distributed along the eastern Australian coastline. Gopurenko and Hughes (2002) highlight that a similar pattern of cladogenesis either side of the Torres Strait is exhibited in a number of other marine species including barramundi (Lates calcarifer), saddle-tail sea perch (Lutjanus malabaricus) and several species of mackeral (Scomberomorus spp.). QFS has given consideration to separate management arrangements for regions within the fishery. The 1999 ‘Queensland Mud Crab Fishery – Discussion Paper’ (the Discussion Paper) sought public comment on the possibility of three discrete management zones; the Gulf of Carpentaria, Moreton Bay and the remainder of the East Coast. Indeed, the then Queensland Fisheries Management Authority (QFMA) issued an investment warning for the Gulf of Carpentaria mud crab fishery to ensure that the possibility of separate management arrangements did not trigger excessive speculative effort. The Discussion Paper cited “[t]he reasons for this separate fishery management arrangement and effort control…are the three objectives of the Fisheries Act 1994” (QFMA 1999, p36). In other words, that management arrangements can more effectively ensure ecologically sustainable use of the mud crab resource, while achieving optimum community and economic benefits and fair access (QFMA 1999, p28). At present, separate management arrangements are still likely for the Gulf of Carpentaria mud crab fishery, and the Gulf investment warning will be enforced. However the exact nature and detail of the management arrangements are still under consideration (Mark Doohan, Fishery Manager, QFS, pers. comm., 2003). Gopurenko et al.’s (1999) and Gopurenko and Hughes’ (2002) results also indicate that the Gulf of Carpentaria population is a shared stock between Queensland and the Northern Territory, and the East Coast population is a shared stock between Queensland and New South Wales. QDPI has a long history of collaboration and co-operation with NSW, NT and WA concerning the mud crab fishery. QDPI has participated in and made presentations at all three Australian mud crab workshops, held in 1993, 1995 and 1999 (Bartleet et al. 1993; Evans 1995; Calogeras 2000). These workshops have focussed on a range of issues including:

• Sharing existing information on the fishery and the biology/ecology of the species

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• Identifying inconsistencies in the management arrangements used in each state/territory

• Developing a co-ordinated research strategy to fill data and knowledge gaps • Focussing research on opportunities for collaborative interstate work between

stakeholders and government agencies. The most important example of interstate collaboration to ensure the sustainable management of Australian mud crab resources is the ‘Five-Year Research Strategy for Australian Mud Crabs’ developed at the 1999 National Mud Crab Workshop (Calogeras 2000). Managers and researchers from Queensland, Western Australia and the Northern Territory were actively involved in the development of the strategy. NSW Fisheries, though not actively involved, endorsed the strategy as “…sensible and of general importance to the future research and management of Australia’s mud crab resources” (Calogeras 2000, p 108). As outlined in criteria 1.1.1, QDPI and NTDBIRD are currently collaborating on phase one of the project to undertake an assessment of techniques for estimating the size of the mud crab resource in northern Australia. 1.1.4 There are reliable estimates of all removals, including commercial (landings and discards), recreational and indigenous, from the fished stock. These estimates have been factored into stock assessments and target species catch levels. Mud crabs are harvested from estuaries along the Queensland coast by commercial, recreational and indigenous fishers. The commercial harvest of mud crabs is documented through CFISH - the Commercial Fisheries Information System. A complete description of CFISH is provided in criteria 1.1.1. A summary of annual statistics for the mud crab fishery is provided in Table 1. Trends in catch and CPUE (kg/day) for the entire Queensland mud crab fishery are presented in Figure 3. Analysis and interpretation of the commercial data trends is provided by Gribble, Brown and Williams (2002). Statewide, the numbers of boats reporting harvest has oscillated significantly, though a general upward trend is apparent. The days fished per boat exhibits a similar pattern – some oscillation with a general upward trend. Accordingly, the total effort of the commercial sector, measured as total boat days fished, has increased though the trend has been variable. Total effort increased significantly during the periods 1992-1993 and 1996-2000. However, over the past two years (2001 and 2002) total effort has again decreased such that the 2002 total effort was back to the 1999 level. Commercial harvest trends have been generally upward with the highest reported catch of about 1000 tonnes in 2000. The current total catch (2002) is approximately equivalent to the 1999 total catch. Mean annual CPUE, measured as daily boat harvest (kg/day), averaged about 21 kg with no substantial upward or downward trend, although there is some variation. The period 1993-1997 was below the mean daily catch rate, while the year 1990 and the period 1999-2002 were above the mean.

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Figure 3. Trends in total catch and CPUE (kg/day) for the entire Queensland mud crab fishery

The top 10% of the fleet, about 50 boats, landed 50% of the harvest and applied 35% of the effort in terms of days fished. These boats typically worked for 160 days per year with a daily harvest of about 30kg. The aggregated statewide CFISH data can also be analysed at a finer spatial scale. Williams (2002) has divided the Queensland coastline into eight regions, to allow regional analysis of CFISH data (see Map 2). Although mud crabs are harvested from estuaries along the entire Queensland coast, approximately 70% of the catch is harvested from three regions. Based on 2001 data, the Capricorn region accounts for approximately 42% of the total catch, the Gulf region approximately 16%, and the Northern Dry region approximately 12% (see Table 2). The catch and CPUE (kg/day) of mud crab for each of the eight regions are included in Figure 4. In general, the regional trends have followed similar patterns to the statewide trends, apart from the Gulf of Carpentaria (Figure 4). Total catch in the Gulf rose from about 30 tonne per year (1989-94) to about 127 tonne in 1997. The 1998 harvest declined to about 50 tonne with the daily harvest per boat declining to pre-1994 levels. However, the 2000 harvest built back up to 156 tonnes, with mean annual daily boat harvest at record levels at about 32 kg, compared to an overall mean of about 19 kg.

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Harvest from the Capricorn region showed the most significant increase (Figure 4). From approximately 86 tonnes in 1988, the catch increased to approximately 210 tonnes in 1993 and 1994, stabilised at approximately 170 tonnes until 1997 then increased again to the maximum harvest of 411 tonnes in 2001. Mean annual daily catch rate has remained about the same at about 23 kg, with some inter-year variation, although this increased to 31 kg in 2000 and 36 kg in 2001. The pattern is generally similar to the statewide catch rate discussed earlier. The increase in production over 1988-2000 is a result of a 52% increase in the number of boats to about 129, and an increase in the total number of days fished to about 11 500 days. Overall, the days fished per boat increased by only about one day per year. However, the top 10% of the producing boats increase effort by about six days per year on average, with mean effort increasing from about 150 to 200 days per year. Both catch and catch rate oscillated similarly in the Northern Dry region (Figure 4). From 42 tonnes and 22kg/day in 1988, catch and catch rate increased to 88 tonnes and 28 kg/day in 1990, decreased to 27 tonnes and 15 kg/day in 1994, then increased again to a maximum catch of 171 tonnes and catch rate of 28kg/day. In the 2002 edition of the biennial ‘Condition and Trend report on Queensland’s Fisheries Resources’, Williams (2002) highlighted that commercial harvest in the Moreton region requires close monitoring (Figure 4). This was based on the fact that the mean annual daily boat harvest is about two-thirds of the rest of the State’s – typically 15 kg with a steady decrease down to 11 kg in 2000. Harvest level increased to a maximum of 90 tonne in 1999, with effort increasing to a peak of 7400 days fished, and the number of boats increasing only marginally to 124. In 2000, harvest declined to 80 tonne, effort decreased to 7100 days fished, and the number of boats decreased to 113. An estimate of the recreational catch of mud crab in Queensland is available through the biennial RFISH telephone and diary surveys conducted in 1997, 1999 and 2001. Results from the 2001 survey round have not yet been published. The 1997 RFISH survey estimated that approximately 700 000 mud crabs were harvested by recreational fishers in that year. The 1999 RFISH survey estimated that approximately one million mud crabs were harvested while a further 2.5 million mud crabs were caught and released. The average mud crab weight of the recreational harvest has not yet been estimated however Williams (2002) suggests that the commercial average weight of 1kg per crab can be used without significant error since the same size restrictions apply to both commercial and recreational fishers. Accordingly, the recreational harvest of mud crabs throughout Queensland is estimated at 600-700 tonnes in 1997 and 900-1100 tonnes in 1999. Although the RFISH surveys utilise a different regional breakdown than is used in CFISH, Gribble, Williams and Brown (2002, p126) states that the recreational catch “…was distributed along the eastern coast of Queensland with similar regional patterns to those of the commercial sector, apart from the Moreton region. It is estimated that the Moreton region recreational harvest was about 260 tonnes in 1997 and 1999”. The catch of mud crabs in Queensland by indigenous fishers and communities is currently being estimated as part of the National Recreational and Indigenous Fishing

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Survey (NRIFS). Latest advice indicates that the indigenous component of the NRIFS will be available when the final NRIFS report is released mid- to late-2003 (J. Higgs, QFS, pers. comm., 2003). The indigenous component of the NRIFS has focussed specifically on northern Australia (Johns 2000); it is likely that an initial estimate will be available for both the Gulf region and the northern section of the Queensland east coast. 1.1.5 There is a sound estimate of the potential productivity of the fished stock/s and

the proportion that could be harvested. and 1.1.6 There are reference points (target and/or limit) that trigger management actions including a biological bottom line and/or a catch or effort upper limit beyond which the stock should not be taken. The estimated total mud crab catch in Queensland is approximately 1800 tonnes, 800 tonnes for the commercial sector and 1000 tonnes for the recreational sector. Without a stock assessment model it is impossible to accurately estimate what percentage of the sustainable harvest the current harvest of 2000 tonnes represents. In considering the sustainability of the current harvest it is important to emphasise once again the risk-averse and conservative management arrangements in place in the Queensland mud crab fishery. The prohibition on harvesting female crabs and the minimum size limit of 15cm CW for male crabs ensures that all female and the majority of male crabs can spawn (QFMA 1999). The external assessment of the Northern Territory mud crab fishery conducted by Walters et al (1997) is also pertinent. The authors estimated that greater than 70 % of the available stock was harvested in any given year in the Northern Territory. Despite the high estimated exploitation rate, Walters et al (1997, p15) suggested there was “…little risk of a conservation problem in the form of recruitment overfishing”. Williams (2002) supports Walters’ (1997) observation, explaining that there are a number of strengths in the life cycle of mud crabs that give them high resilience to fishing pressure. These include very high fecundity, a protracted spawning period, rapid growth, and early sexual maturation (Williams 2002). These strengths are further enhanced in the Queensland mud crab fishery due to the more stringent management arrangements enforced compared to the Northern Territory. As was outlined in criteria 1.1.2, no stock assessment model or estimate of stock size is currently available for the Queensland mud crab fishery or any other mud crab fishery in Australia. The reasons for this primarily relate to the inappropriateness of traditional assessment models and methods due to several biological characteristics of the species and operational practices utilised in the fishery (see criteria 1.1.2). The NTDBIRD-FRDC-QDPI Mud Crab Project is currently developing a novel ‘habitat-alias’ stock assessment methodology for northern Australian mud crab fisheries. For greater detail see criteria 1.1.1 and 1.1.2 or Hay and Phelan (2002). QFS has a reliable 15-year time-series of data on commercial catch and effort, and an increasingly accurate estimate of recreational catch and effort. Accordingly, once the

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NTDBIRD-FRDC-QDPI ‘habitat-alias’ stock assessment methodology has been developed and operationalised, QFS will be much better placed to assess the sustainability of management measures used in the mud crab fishery. Until the stock assessment model is fully developed, QFS will continue to ensure that Queensland’s mud crab harvests are sustainable through monitoring of the fishery-dependent and –independent information. As outlined in criteria 1.1.2, the regular Condition and Trend Report (Williams 2002) and Status Reports to CrabMAC (Gribble and Williams 2001) are the major assessment reports based on fishery-dependent information. These reports outline commercial catch/effort trends, ongoing fishery-independent monitoring, and current research. The primary assessment reports based on fishery-independent information are the biennial status reports from the Long-Term Monitoring Program. Concerning the mud crab fishery, the reports will outline the condition of and changes to mud crab abundance, stock characteristics such as size and sex ratio, and habitat. The reports are based on the annual fishery-independent LTMP surveys conducted along the East Coast and in the Gulf of Carpentaria (see Helmke et al. 2002). QFS recognises that reference points provide a valuable yardstick against which to assess the sustainability of fish stocks and to indicate appropriate time frames for management intervention. However, at present no reference points are currently used in the management of the mud crab fishery; the development of a reliable stock assessment model and methodology has taken priority as the logical first step. This first priority was jointly developed and agreed to by QDPI, NTDBIRD, and FisheriesWA in the ‘Five-Year Research Strategy for Australian mud crab resources’ (Calogeras 2000). NSW Fisheries, though not directly involved, fully endorsed the strategy and its priorities as “…sensible and of general importance to the future research and management of Australia’s mud crab resources” (Calogeras 2000). It is envisaged that the final report of the NTDBIRD-FRDC-QDPI Mud Crab Project will provide biological reference points to assist the sustainable management of the mud crab fishery by developing techniques to estimate the size of the mud crab resource across the stocks range (Hay and Phelan 2002). 1.1.7 There are management strategies in place capable of controlling the level of take. The Queensland Fisheries Service, a part of QDPI, manages the Queensland mud crab fishery under the Fisheries Act 1994 (the Act) and subordinate legislation included in the Fisheries Regulation 1995 (the Regulations). The objectives of the Act were amended in September 2002 to more accurately reflect current interpretations of the ESD principles adopted by Queensland and all Australian governments in the National Strategy for ESD (COAG 1992). The listed objectives of the Act are outlined below.

1. The main purpose of the Act is to provide for the use, conservation and enhancement of the community’s fisheries resources and fish habitats in a way that seeks to - (a) apply and balance the principles of ecologically sustainable development (b) promote ecologically sustainable development.

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2. In balancing the principles, each principle is to be given the relative emphasis appropriate in the circumstances.

3. In the Act - “ecologically sustainable development” means using, conserving and enhancing

the community’s fisheries resources and fish habitats so that – (a) the ecological processes on which life depends are maintained; and (b) the total quality of life, both now and in the future, can be improved.

“principles of ecologically sustainable development” means the following

principles – (a) enhancing individual and community well-being through economic

development that safeguards the well-being of future generations; (b) providing fairness within and between generations; (c) protecting biological diversity, ecological processes and life-support

systems; (d) in making decisions, effectively integrating fairness and short and long-term

economic, environmental and social considerations; (e) considering the global dimension of environmental impacts of actions and

policies; (f) considering the need to maintain and enhance competition, in an

environmentally sound way; (g) considering the need to develop a strong, growing and diversified economy

that can enhance the capacity for environmental protection; (h) that decisions and actions should provide for broad community involvement

on issues affecting them; (i) the precautionary principle.

“precautionary principle” means the principle that, if there is a threat of serious or

irreversible environmental damage, lack of scientific certainty should not be used as a reason to postpone measures to prevent environment degradation, or possible environmental degradation, because of the threat.

The Act provides QFS with extensive mechanisms that ensure it can respond in a timely manner to any threats to the sustainability of the fishery. These include the power to:

a) declare a closed season, closed waters or closed species (section 43 of the Act); b) declare a quota for a fishery (section 44); c) make an emergency fisheries declaration (section 46) where urgent action is

needed to meet a significant threat to fisheries resources or habitat; d) refuse to issue or renew an authority (section 59) where it is necessary or

desirable for the best management or protection of fisheries resources; e) impose conditions on issue or renewal of an authority (section 61); f) amend an authority (section 63); and g) suspend or cancel an authority (section 67) where it is necessary or desirable for

the best management, use, development or protection of fisheries resources or fish habitats.

Currently, no formal management plan exists specific to the mud crab fishery. As mentioned in the introduction, in 1999 the Queensland Fisheries Management Authority (QFMA) released the ‘Discussion Paper - Queensland Mud Crab Fishery’

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(QFMA 1999) seeking public comment and input on an extensive range of issues facing the fishery (see Appendix 3 for a complete list of the issues raised for public comment). Primary among these issues was the separation of the Gulf and the East Coast mud crab fisheries. The Discussion Paper sought comment on the development of separate fishing symbols, management arrangements and management plans for the Gulf and the East Coast. Previous to the Discussion Paper, QFS, with the full support of CrabMAC, had indicated its intent to develop separate management arrangements for the Gulf through the ‘1997 Investment Warning for the Gulf of Carpentaria Mud Crab Fishery’ (QFMA 1999). The investment warning advised all interested parties that “…investment and catches after the date of [the] warning [were] extremely unlikely to be recognised in determining eligibilities for future participation in the [Gulf] fishery” (QFS media release, cited in QFMA 1999). The release of the Discussion Paper was the first step in developing a formal Management Plan for the fishery. QFMA distributed approximately 2800 copies of the Discussion Paper to stakeholders and groups directly and indirectly involved in the fishery. A significant level of public response was received, comprised of:

• 24 responses from organisations/groups/branches; • 82 responses from commercial fishers; • 123 responses from recreational fishers; • 1 response from an indigenous fisher; and, • 9 responses from ‘other’ stakeholders.

QFMA collated and analysed the responses. CrabMAC also analysed the responses and provided comments and recommendations. The development of the Mud Crab Fishery Management Plan is awaiting implementation of management plans in higher priority fisheries (Mark Doohan, Fishery Manager, QFS, pers. comm., 2003). Currently, QFS ensures the sustainable management of the Queensland mud crab fishery through a range of input and output controls (Table 4). In common with all Queensland’s commercial fisheries, limited entry arrangements are in place in the mud crab fishery meaning that no new commercial crabbing licenses are being issued. 794 licenses are currently endorsed to harvest mud crabs (known as a C1 symbol), however in 2002 only 468 of those vessels recorded mud crab catch. Broadly speaking, input controls limit fishing effort (and therefore catch) by placing restrictions on the number of fishers, the time and place of fishing and on the gear used to harvest a stock (QFMA 1999). The restrictions on the number of commercial fishers and the age of recreational fishers, and the number and type of mud crab apparatus used are the primary input controls used in the mud crab fishery (see Table 4). Queensland enforces the most rigorous restrictions on the permitted number of pots/dillies of any Australian state for both the commercial and recreational sectors:

• Queensland – commercial 50 pots, recreational 4 pots • Northern Territory – commercial 60 pots, recreational 5 pots • Western Australia – recreational 10 drop nets

As part of the restriction on apparatus type, a ban exists on ‘hooking’ mud crabs; this minimises the potential for destructive fishing practices to harm the stock. Output controls limit the level and type of catch taken in a fishery (QFMA 1999). There are a number of output controls in place in the mud crab fishery (see Table 3).

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These deal with a variety of sustainability issues relevant to the fishery. The minimum legal size limit for male mud crabs and the prohibition on harvesting female mud crabs are designed to address biological aspects of overexploitation. The minimum legal size that male mud crabs must attain before harvest is permitted is 15cm carapace width (CW) for both recreational and commercial fishers in the Queensland mud crab fishery. This is the most conservative size restriction enforced in any mud crab fishery in Australia. The minimum legal size restrictions enforced in other Australian states are:

• Northern Territory – males 13cm CW, females 14cm CW • Western Australia – green 12cm CW, brown 15cm CW • New South Wales – males and females 13cm CW (measured as 8.5cm carapace

length (CL)) Brown (1993) summarised a number of studies on mud crab growth and sexual maturity from a variety of latitudes, and found a considerable degree of variation in both age and size at which mud crabs reach maturity. Sexual maturity has been observed to occur between 12-18 months and 9.0 – 10.0cm in tropical latitudes (e.g. Philippines, Malaysia, PNG) while in sub-tropical latitudes such as south-east Queensland maturity has been estimated to occur at approximately 13.8cm and up to 27 months (Heasmann 1980). Therefore, the 15cm CW minimum size enforced in the Queensland mud crab fishery allows a significant proportion of male mud crabs to mate before becoming available to harvest. In addition, most male crabs greater than 15cm CW are described as being in ‘growth phase IV’ based on moulting cycles. ‘Growth phase IV’ crabs have a larger claw size to body size ratio than more immature phases, and since almost half the meat of a male crab is contained in the claws, have relatively more meat and therefore more value (Heasmann 1980; Hill 1984). Harvesting female mud crabs is banned in Queensland, a measure that has been in place since 1913 (Coates 1993). Queensland is the only state in Australia that provides blanket protection for the female component. Accordingly, there has been some debate among the states concerning the advantages and disadvantages of the measure. QFS maintains that the female prohibition is a precautionary management control aimed at conserving the spawning stock of the fishery and therefore enhances the sustainability of the fishery. In an assessment of the Northern Territory mud crab fishery, Walters et al. (1997) suggested that the mud crab stock could withstand a very high exploitation rate in part due to the “…partial refuge from exploitation for female mud crabs because of their offshore spawning migration into areas that are not fished” (Walters et al. 1997, p 15). The prohibition on female harvest in the Queensland mud crab fishery can be seen to further strengthen the protection of females from exploitation. Furthermore, present knowledge of the dynamics of mud crab populations is insufficient to accurately predict the outcome of lifting the long-term prohibition (QFMA 1999). On several levels, the precautionary principle supports the continued prohibition on harvesting female mud crabs. The other output controls in place address different issues. The recreational in possession limit of 10 crabs per person aims to limit the exploitation of the stock by the recreational sector; and to instil a more conservative and equitable approach among recreational fishers (QFMA 1999). Both the Northern Territory and Western Australia enforce a similar recreational in possession limit of 10 crabs per person. The prohibition on possessing crabmeat, or crab claws separate from the carapace aims to

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maximise fisher compliance with management arrangements. Specifically, it minimises the potential for either recreational or commercial fishers to avoid the size and sex restrictions enforced in the fishery.

1.1.8 Fishing is conducted in a manner that does not threaten stocks of by-product species.

All available evidence suggests that the take of non-target species, including byproduct, in the Queensland mud crab fishery is minimal. Preliminary results on non-target catch obtained by QFS through fishery-independent surveys conducted in the Long-Term Monitoring Program indicate an average non-target CPUE of approximately one individual every three to four pot lifts (for greater detail see criteria 2.1.1 and 2.1.2). Anecdotal evidence from researchers and fishers in both Queensland and the Northern Territory supports that minimal non-target catch is taken. The minimal take of non-target species is due primarily to the fishing gear and methods used in the fishery. For greater detail on the composition, abundance, and risk associated with non-target catch see Principle 2, particularly criteria 2.1.1 to 2.1.3. Concerning byproduct from the mud crab fishery, very little of the non-target catch that is taken is considered useful or desirable as byproduct. Comments from QDPI researchers with experience in the mud crab fishery indicate that commercial fishers opportunistically use some larger fish, particularly cod and catfish, as bait for crab pots (Steve Bailey, AFFS, pers. comm., 2002; Stirling Peverell, QFS, pers. comm., 2002). Blue swimmer crabs may be retained for sale as a byproduct species. To operate in the Queensland mud crab fishery, commercial fishers must possess a C1 symbol. Under a C1 symbol, all commercial crab species may be harvested, with the exception of spanner crabs. Therefore, mud crab fishers may legally retain blue swimmer crabs for sale, subject to the management restrictions in place for blue swimmer crabs. However, the byproduct catch of blue swimmer crabs is not considered a significant risk, as the two species do not generally co-habit the same local areas. Mud crabs inhabit muddy mangrove areas while blue swimmer crabs are more commonly found on sandier offshore habitats (Grant 1997; Sumpton et al. 2003). While there may be some overlap in the habitats for mud crabs and blue swimmer crabs, Sumpton et al. (2003) found that on observer trips with commercial blue swimmer crab fishermen only 263 mud crabs were caught in over 7000 pot lifts. Over 50,000 blue swimmer crabs were captured during these trips. There were also strong regional differences in the catch; mud crabs were found to be rare in the offshore areas where the majority of blue swimmer crabs are fished. Adding further support, the preliminary non-target catch data obtained by QFS to date through the LTMP and by QDPI through the NTDBIRD-FRDC-QDPI Mud Crab Project reveals that blue swimmer crabs are only infrequently caught in large numbers in the mud crab fishery (see criteria 2.1.1 and 2.1.2 for greater detail). The logbooks used in both the East Coast and Gulf regions of the mud crab fishery separate the mud crab and blue swimmer crab catch; therefore QFS is able to monitor the extent of blue swimmer crab bycatch.

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The mesh size of the mud crab pots also ensures that juvenile blue swimmer crabs can escape. The survival of released blue swimmer crabs, whether captured in pots or trawls, is high (Sumpton et al. 2003). The catch and release of female and non-legal size male crabs is not considered a significant byproduct risk due to the high survivability of both groups to capture and release. Survivability is largely influenced by two factors: the duration of entrapment; and the severity of physical damage from either the fishing gear used or the weight and body structure of other caught individuals. Commercial and recreational pots/dillies are generally checked on a daily basis; this limits the time of capture to a maximum of twenty-four hours. All trapped crabs remain in the water for the duration of that time. The time out of the water is limited to checking and clearing the pot. Management regulations require all female and undersize male crabs to be quickly returned to the water at the point of capture. With regard to physical damage, mud crab pots are relatively benign as they function by trapping; mud crabs are enticed into the pots by bait and their exit is restricted by the small size of the pot openings. The rigid size and structure of the pots, generally hard plastic or wire mesh, and the low number of mud crabs and non-target individuals ‘trapped’, effectively eliminates the potential for either females or undersize male crabs to be crushed or damaged. Fishery-independent sampling supports that mud crabs are highly resilient to capture and release. In a series of tag-recapture experiments Knuckey (1999 cited in NTDBIRD 2002)) found that caught and released mud crabs exhibited high survivability and good condition over both the short-term (i.e. within the same sampling round - days) and the long-term (i.e. the next sampling round – months). 1.1.9 The management response, considering uncertainties in the assessment and precautionary management actions, has a high chance of achieving the objective. The current management arrangements in place in the Queensland mud crab fishery are the most conservative and precautionary of any Australian state or territory mud crab fishery, for both the commercial and recreational sectors. The prohibition on harvesting females ensures that the entire female component of the stock is able to spawn while the 15cm CW minimum size for males ensures that a majority of males reach sexual maturity and are able to spawn before becoming available to harvest. The spawning potential of mud crab populations in Queensland is highly protected such that recruitment overfishing is not considered a threat. The female prohibition and the male minimum size also render growth overfishing unlikely. The restriction on the number of pots that may be used (50 for commercial fishers, 4 for recreational fishers) and the 10-crab in possession limit for recreational fishers ensure that the effort and catch in the fishery remains within sustainable levels. There is a reliable information collection system in place in the fishery including both fishery-dependent and fishery-independent data. The CFISH program provides a long time-series of reliable fishery-dependent data on the commercial catch and effort in the fishery. This information is sourced from the daily logbook records that all commercial fisher’s are required to return to QFS as a condition of operation. Similarly, the RFISH program provides a reliable, and relatively long, time-series of

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fishery-dependent information on the recreational harvest in the fishery. Indeed, with three recreational fishing surveys completed (1997, 1999, 2002), Queensland has the most advanced ongoing assessment of statewide recreational fish catch of any state in Australia. The final report of the NRIFS, due mid- to late-2003, will also provide a first estimate of the indigenous and international visitor catch of mud crabs in northern Queensland. The strong commitment to collecting and analyzing fishery-independent data on the mud crab fishery is most notably evident through the primary current monitoring program, the Long-Term Monitoring Program (LTMP), and the primary current research project, the collaborative NTDBIRD-FRDC-QDPI Mud Crab Project. The aim of the LTMP is to develop a long-term time-series of data on key parameters to the mud crab stock. This will allow QFS to detect and evaluate any potential changes in stock abundance, structure and habitat. The NTDBIRD-FRDC-QDPI Mud Crab Project is developing a reliable methodology to assess the status of the mud crab stock. As outlined in criteria 1.1.2, this is the primary research priority agreed to by the relevant Australian states/territories in recognition that traditional stock assessment methods are inappropriate for mud crab stocks. The information outlined in criteria 1.1.1 to 1.1.8 clearly shows the adequacy of the information, assessment and management aspects pertaining to the target species of the Queensland mud crab fishery (Scylla serrata). Both the management regime and the current catch levels are sustainable. Objective 2. Where the fished stock(s) are below a defined reference point,

the fishery will be managed to promote recovery to ecologically viable stock levels within nominated timeframes.

Management responses 1.2.1 A precautionary recovery strategy is in place specifying management actions,

or staged management responses, which are linked to reference points. The recovery strategy should apply until the stock recovers, and should aim for recovery within a specific time period appropriate to the biology of the stock.

And 1.2.2 If the stock is estimated as being at or below the biological and / or effort

bottom line, management responses such as a zero targeted catch, temporary fishery closure or a ‘whole of fishery’ effort or quota reduction are implemented.

Queensland has a long-term commitment to ESD principles, most notably through the Fisheries Act 1994. The recent Primary Industries Legislation Amendment Act 2002 (PILA Act) has further refined and focussed QFS’ ESD obligations to ensure “…the use, conservation and enhancement of the community’s fisheries resources and fish habitats…”. As detailed in criteria 1.1.1 to 1.1.9, available evidence suggests that current levels of catch and effort are sustainable. Some concerns have been noted concerning the large

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catch and effort increases in parts of the Gulf of Carpentaria since the mid-1990s (criteria 1.1.4, and Helmke et al. 1998; QFMA 1999). In recognition of these concerns, an investment warning for the Gulf mud crab fishery was issued to all potential investors, current commercial crab fishers and boat owners. A collaborative research project between QDPI and the Weipa Catchment Coordinating Group to assess the status of mud crab stocks in the Weipa region has also been undertaken in response to community, recreational and indigenous concerns about the sustainability of the local fishery (Helmke et al. 1998). Two project reports have been released to date (Helmke et al. 1998; Gould et al. 2001) both of which indicate that stocks in the Weipa region are likely to be ‘fully exploited’, though within long-term sustainable levels. A third project report is due in 2003. QFS recognises that reference points provide a valuable yardstick against which to assess the sustainability of fish stocks and to indicate appropriate time frames for management intervention. However, before reference points can be established an accurate and reliable stock assessment process is necessary. QFS, in cooperation with the Northern Territory, is currently focussing significant attention on developing such a model through the NTDBIRD-FRDC-QDPI Mud Crab Project.

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PRINCIPLE 2. Fishing operations should be managed to minimise their impact on the structure, productivity, function and biological diversity of the ecosystem. Objective 1. The fishery is conducted in a manner that does not threaten

bycatch species. Information requirements 2.1.1 Reliable information, appropriate to the scale of the fishery, is collected on the composition and abundance of bycatch. To date, limited research has been targeted at quantifying the bycatch taken in the commercial, recreational or indigenous mud crab fisheries. This is largely due to the view among Queensland and interstate researchers and commercial fishers that bycatch levels are minimal. However, QFS acknowledges that the assumption of limited bycatch must be quantified in order to demonstrate commitment to ecologically sustainable development (ESD) and the precautionary principle, both primary objectives of the Fisheries Act 1994. In recognition of the heightened priority afforded to bycatch issues under ESD principles, QFS has sought to make the recording of bycatch information standard practice in fishery-independent stock sampling. To illustrate, during 2001 the decision was made that from the start of 2002 all sampling in the Long-Term Monitoring Program (LTMP) would record bycatch species composition and abundance. As the LTMP sampling utilises similar fishing gear and methods as the commercial fishery in a variety of locations, the results will be highly applicable to the commercial mud crab fishery. Complete bycatch species composition, and estimates of abundance and bycatch CPUE for the 2002 LTMP sampling will be available in the 2002 LTMP report due by mid-2003. At this preliminary stage, bycatch species composition and abundance are available for the southern east coast, northern east Coast and the Gulf of Carpentaria (Tables 6, 7 and 8 respectively). It is important to strongly stress that these results have not yet undergone rigorous scientific analysis and have not been published, and therefore must only be considered rough approximations. Nevertheless, they offer a useful initial indication of total bycatch species composition and abundance. As mentioned in criteria 1.1.1, each site (river system) sampled in the LTMP is divided into four areas – foreshore, mouth, mid estuarine and upper estuarine. Nine sites were sampled in the southern section of the East Coast in 1999. In both the northern section of the East Coast and the Gulf of Carpentaria four sites were sampled (see Map 3).

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Table 6. Species composition and abundance of bycatch caught during the 2002 sampling season of the Long-Term Monitoring Program (720 pot lifts). Southern East Coast – Connor Creek (Rockhampton region) to Logan River (Moreton Bay region).

Table 7. Species composition and abundance of bycatch caught during the 2002 sampling season of the Long-Term Monitoring Program (320 pot lifts). Northern East Coast – Bizant River (Princess Charlotte Bay region) to Bowling Green Bay (Townsville region).

Scientific Name Common Name Sum of CountPortunus pelagicus blue swimmer crab 117Thalamita crenata Mangrove crab 30Arius spp catfish 12Epinephelus coioides orange-spotted grouper 12Xanthidae - undifferentiated [a crab] 11Brachaelurus waddi blind shark 3Monacanthus chinensis fan-bellied leatherjacket 2Aptychotrema vincentiana western shovelnose ray 1Carcharhinus macloti hardnose shark 1Microcanthus strigatus stripey 1Muraenesox cinereus dark-finned pike eel 1Platycephalus arenarius northern sand flathead 1Pomadasys spp. grunter bream 1Total Bycatch 193

Scientific Name Common Name Sum of CountArius spp catfish 47Portunus pelagicus blue swimmer crab 14Acanthopagrus berda pikey bream 6Nibea squamosa jewelfish 5Protonibea diacanthus black jewfish 5Epinephelus coioides orange-spotted grouper 3Jelly Fish Jelly Fish 3Epinephelus malabaricus Malabar grouper 2Paguridae - undifferentiated hermit crabs 2Nibea soldado silver jewfish 2Scatophagidae - undifferentiated scats 2Triodontidae - undifferentiated pufferfishes 2Carcharhinidae shark 1Dasyatididae - undifferentiated stingrays 1Eleutheronema tetradactylum blue threadfin 1Soleidae - undifferentiated soles 1Amniataba percoides banded grunter 1Netuma thalassinus common forktailed catfish 1Total Bycatch 99

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Table 8. Species composition and abundance of bycatch caught during the 2002 sampling season of the Long-Term Monitoring Program (320 pot lifts). Gulf of Carpentaria – Weipa region to Norman River (Karumba region).

Additional bycatch information is also available through the collaborative NTDBIRD-FRDC-QDPI Mud Crab Project. In 2001 and 2002, QDPI’s Agency for Food and Fibre Sciences (AFFS) staff carried out six fishery-independent mud crab surveys across a range of north-Queensland sites in Karumba, Princess Charlotte Bay and Trinity Inlet (Gribble and Bailey 2002). Species composition and abundance of all bycatch, alive and dead, was recorded. The aggregated data set represents approximately seven full weeks of sampling at an effort of 100 pots/day and one haul/day. The complete results will be available in the final project report due in June 2004. However, research staff have provided preliminary results in the form of a species composition list (Table 9). Table 9. Species composition list of bycatch caught during the AFFS mud crab surveys as part of the NTDBIRD-FRDC-QDPI Mud Crab Project Fish Species Crustacean Species Toadfish Sickle fish Blue swimmer crabs Catfish King salmon Stone crab Bream Shark Banana prawn Gold spot cod Sole Tiger prawn Silver Jew Ambassids Hermit crabs Barramundi Threadfin Stargazer Pike eel Estuary cod Moses perch

Scientific Name Common Name Sum of CountPortunus pelagicus blue swimmer crab 33Epinephelus coioides orange-spotted grouper 14Xanthidae - undifferentiated [a crab] 8Paguridae - undifferentiated hermit crabs 7Acanthopagrus berda pikey bream 5Epinephelus malabaricus Malabar grouper 4Arius spp catfish 4Thalamita crenata Mangrove crab 3Scatophagidae - undifferentiated scats 2Dasyatididae - undifferentiated stingrays 2Epinephelus spp Black Spot Cod 1Uranoscopidae - undifferentiated stargazers 1Pomadasys argenteus spotted grunter 1Triodontidae - undifferentiated pufferfishes 1Ambassis spp Glassfish 1Acanthopagrus australis yellowfin bream 1Carcharhinidae shark 1Halophryne diemensis [a frogfish] 1Latrididae - undifferentiated trumpeters 1Platycephalus spp Flathead 1Total Bycatch 92

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From the unpublished aggregated data set for all sites surveyed by AFFS under the NTDBIRD-FRDC-QDPI Mud Crab Project, crustacean species represented 60% of bycatch taken and fish species 40%. However, these figures are strongly influenced by the bycatch of blue swimmer crabs, which represented approximately 50% of all bycatch taken. Although blue swimmer crabs were the most dominant single bycatch species, their inclusion in the bycatch breakdown percentages is somewhat misleading. Blue swimmer crabs were only caught at four of the eleven survey sites, and only in significant numbers at three sites, all in Trinity Inlet. However, at those three sites, the numbers caught were very large. To illustrate, the number of blue swimmer crabs caught at the three major Trinity Inlet sites was greater than the total bycatch of all other species caught during all the surveys. Comments from researchers suggest that logistical difficulties in setting ‘research’ pots in some foreshore areas (e.g. water too shallow for boat access) means that the pots are sometimes set in habitats more commonly associated with blue swimmer crabs than mud crabs. It is unlikely that either commercial or recreational fishers targeting mud crab would set pots in such areas. Accordingly, the ‘experimental’ bycatch of blue swimmer crabs is an overestimate of commercial or recreational blue swimmer crab bycatch. Despite the large bycatch of blue swimmer crabs, the mortality rate was extremely low - less than 5%. Given the high resilience of blue swimmer crabs to trapping and capture the mud crab fishery is believed to have only a negligible impact on the blue swimmer crab stock and fishery. Excluding blue swimmer crabs, fish species represented 80% of the bycatch taken and ‘other’ crustacean species just 20%. The major bycatch fish species included toadfish, catfish, cod, and bream. Hermit crabs were the dominant ‘other’ crustacean bycatch species. In interpreting the above information it must be remembered that the AFFS surveys for the NTDBIRD-FRDC-QDPI Mud Crab Project were conducted at only a limited number of sites in northern Queensland waters. Therefore, the results may not be generally applicable to the entire range of the Queensland mud crab fishery. Nevertheless, when published, the results will represent a valuable initial quantitative ‘snapshot’ of bycatch in the Queensland mud crab fishery. Assessment 2.1.2 There is a risk analysis of the bycatch with respect to its vulnerability to fishing. As mentioned in the previous criteria, comments from Queensland and interstate researchers and commercial fishers indicate that bycatch levels in the mud crab fishery are very small. There is little apparent risk of significant impacts to bycatch species. The preliminary bycatch results obtained by QFS thus far from the LTMP indicate an average bycatch CPUE of approximately one individual every three to four pot lifts. In reality however, the number of organisms that can accurately be described as bycatch is much lower. Comments from researchers conducting the fishery

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independent surveys highlight that a significant proportion of organisms recorded as bycatch are not actually trapped in the crab pots but rather are opportunistic feeders that, due to their small size and/or body form, freely move in and out of the pots (Sue Helmke, pers. comm., 2002). Small fish, crabs and other crustaceans such as prawns fall in this category. In addition to the minimal amount of bycatch, that which is caught is assumed to have a high survivability. To illustrate, dead bycatch represented less than 5% of all bycatch taken in the AFFS population surveys conducted for the NTDBIRD-FRDC-QDPI Mud Crab Project. As has been mentioned previously, the AFFS surveys utilise gear, bait and set times similar to the commercial fishery. Bycatch survivability is largely influenced by two factors: the duration of capture or entrapment (e.g. the time out of water); and the severity of physical damage from either the fishing gear used or the weight and body structure of other bycatch. Concerning the first factor, commercial and recreational pots are generally checked on a daily basis which limits the time of capture to a maximum of twenty-four hours. Bycatch species remain in the water for the duration of that time; the time out of the water is limited to checking and clearing the pot. Management regulations require all non-retained catch to be quickly returned to the water at the point of capture. In addition, a number of the bycatch species, particularly other crab species, are capable of withstanding extended periods out of the water. Concerning the second factor, mud crab pots generally don’t inflict physical damage to caught species as they function by trapping; mud crabs and other species are enticed into the pots by bait and their exit is restricted by the small size of the pot openings. The rigid size and structure of the pots, generally hard plastic or wire mesh, and the low level of bycatch ‘trapped’ effectively eliminates the potential for bycatch to be crushed or damaged through the weight or body structure of other bycatch species. Comments from field researchers outline that some fish species that enter pots such as catfish, cod and eels are powerful enough to break their way out of pots (Steve Bailey, pers. comm., 2002). In such instances it is likely that other bycatch species would suffer damage or mortality. However, such impacts are considered to be rare rather than regular. Bearing in mind the preliminary bycatch results obtained by QDPI thus far (LTMP, NTDBIRD-FRDC-QDPI Mud Crab Project); the comments from researchers and fishers; and the fishing gear and methods employed, the mud crab fishery is believed to impart only a minimal negative impact to bycatch species. No formal risk assessment is warranted at this time. Management responses 2.1.3 Measures are in place to avoid capture and mortality of bycatch species unless it is determined that the level of catch is sustainable (except in relation to endangered, threatened or protected species). Steps must be taken to develop suitable technology if none is available.

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Given the low amount and high survivability of bycatch in the mud crab fishery, there appears no need for bycatch reduction measures at present effort levels. Bycatch monitoring is now a priority issue for QDPI with both the LTMP and the NTDBIRD-FRDC-QDPI Mud Crab Project providing data. Should bycatch levels show any increase assessed as significant, specific management responses will be developed to reduce the impacts to a sustainable level in a timely manner. 2.1.4 An indicator group of bycatch species is monitored. and 2.1.5 There are decision rules that trigger additional management measures when there are significant perturbations in the indicator species numbers. and 2.1.6 The management response, considering uncertainties in the assessment and precautionary management actions, has a high chance of achieving the objective. As has been outlined in the preceding criteria (2.1.1 – 2.1.3), at current levels of effort, utilising current fishing gear and methods, and under current management arrangements, QDPI considers the Queensland mud crab fishery does not threaten bycatch species. No information, formal or anecdotal, exists to suggest that any particular species or suite of species is negatively impacted. Accordingly, no specific indicator species have been identified or are being monitored. The LTMP and the NTDBIRD-FRDC-QDPI Mud Crab Project both monitor and record general bycatch information specifically for the Queensland mud crab fishery. Should any negative impacts be identified to bycatch species in general or to a particular bycatch species, QDPI will develop and implement specific management responses to reduce the impacts to a sustainable level in a timely manner. Objective 2. The fishery is conducted in a manner that avoids mortality of,

or injuries to, endangered, threatened or protected species and avoids or minimises impacts on threatened ecological communities.

Information requirements 2.2.1 Reliable information is collected on the interaction with endangered, threatened or protected species and threatened ecological communities. Under the current logbook program, mud crab catch taken in the Gulf of Carpentaria is reported in the ‘Logbook for the Gulf Set Net Fishery’ and mud crab catch taken on the East Coast is reported in the ‘Net and Crab Fishery Logbook’ (see Appendix 1 and 2 respectively). Both logbooks have separate sections in which fishers must record all interactions with threatened or protected species. The instruction sheets provided to

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all fishers using either logbook clearly outline the requirements and obligations involved:

“Under the Fisheries Act 1994 (the Act) and the Fisheries Regulation 1995 (the Regulation), and other State and Commonwealth legislation, you have an obligation to report interactions with threatened or protected species to the relevant Government Department. The Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act) requires that a person reports the death or injury of any animal listed as threatened, migratory, marine or a cetacean under the EPBC Act in a Commonwealth Area to the Secretary, Environment Australia.”

Careful examination of the example logbook pages in Appendices 1 and 2 reveals that the present logbook configuration does not allow interactions with endangered, threatened or protected species to be traced back to the mud crab fishery specifically, since both netting and crabbing operations are entered on the same page. However, during 2003 all license holders will be issued with a Species of Conservation Interest logbook (SCOI0l). With this logbook fishers will be able to differentiate the particular activity that caused the interaction (Shane Gaddes, pers. comm., 2002). Modifications to the bi-ennial estimates of recreational catch and effort (RFISH) will also enhance QFS’ information base concerning interactions. As detailed in criteria 1.1.1, the new RFISH estimates will record information specific to the area of fishing rather than to the area of residence. This has positive ramifications for interactions with endangered, threatened or protected species as QFS will be better positioned to assess the source, primarily recreational or commercial, of any actual or potential interactions generally, and for specific regions. There is also a requirement in the annual fishery-independent Long-Term Monitoring Program (LTMP) surveys of the mud crab resource to maintain written records of any observed interaction between the fishing gear or its operation and any endangered, threatened or protected species. Researchers are also requested to record any instances of unusual catches of any species which might be of value in determining which, if any, marine ecological communities are potentially at risk due to the mud crab fishery. Anecdotal evidence from commercial fishers and researchers suggest that there is only a very minimal risk of mortality of, or injuries to, endangered, threatened or protected species. The 1999 Queensland Mud Crab Fishery Discussion Paper (QFMA 1999), produced as a preliminary public consultation step in creating a management plan for the fishery, sought comment on the issue of turtle interactions (see Appendix 3). The issue was specifically highlighted as there have been isolated incidents where turtles, while appearing to be seeking food, have entangled themselves in crab apparatus, particularly float lines (QFMA 1999; Col Limpus, pers. comm., 2002). In the course of fishery-independent research conducted by QDPI, the only notable potential interaction apparent between turtles and mud crab fishing gear occurred during the AFFS mud crab population surveys as part of the NTDBIRD-FRDC-QDPI Mud Crab Project.

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As was mentioned in criteria 2.1.1, AFFS conducted surveys in the Gulf of Carpentaria (Weipa and Karumba) and along the northern section of the East Coast (Princess Charlotte Bay and Trinity Inlet). During the first pilot survey in Princess Charlotte Bay (Bizant River) in 2001, ten of the forty pots set were badly damaged on the last day of the survey. The entrances to the ten pots had all been broken with the plastic bait bags torn open, torn in half or missing. In a number of instances the mesh of the pots had been ripped open from the top to allow access to the bait bags. There was no evidence to show that the crabs caught in the pots were also being targeted. Undamaged crabs were still caught in several of the damaged pots and no discarded crab remains (e.g. carapace, legs, claws etc.) were recovered (Steve Bailey, pers. comm., 2002). As the pots were only damaged on the last day of surveying, the site was retained as a survey site for the 2002 season. During the first survey in June 2002 over 50% of the pots were damaged in the same manner in the first 24-hour soak period. Initially, each of the pots were repaired and re-baited however twenty of the forty pots suffered the same treatment over the second 24-hour soak period (Gribble and Bailey 2002). Several sources of information suggest that turtles were responsible for the pot damage. Local commercial and indigenous fishers almost universally ascribed the damage to turtles raiding the pots for the fish baits (mullet). Furthermore, the cuts and tears in the pots and bait bags were all very clean; more likely to have been sheared by a beak rather than chewed and lacerated by teeth, as would be the case with most fish species. Although the above examples from the Bizant River surveys appear to indicate that significant interactions between turtles and mud crab apparatus do potentially occur, the survey design differed considerably from normal commercial and recreational potting operations. The survey utilised a web-array design, which requires a very high pot density (Hay and Phelan 2002). Thirty pots spaced at 40m intervals and forty pots spaced at 20m intervals were utilised in the 2001 and 2002 surveys respectively. In contrast, Williams and Hill (1982) recommend 100m as the optimal pot spacing to maximise commercial catches since one pot is generally capable of fishing a 50m radius. Commercial fishers, who are limited to 50 pots, rarely arrange their pots closer than 100m, and would rarely achieve the pot density of the fishery-independent surveys. Researchers involved in the project have suggested that the high pot density, and therefore high bait density, may have attracted turtles to the area and provided an abundant, easily accessible food source (Steve Bailey, pers. comm., 2002). In support of this theory, for four consecutive years the LTMP, which uses a conventional 100m pot spacing, has surveyed the same sites in the Bizant River in which the pot damage occurred, yet has experienced no damage or interactions with turtles. Assessments 2.2.2 There is an assessment of the impact of the fishery on endangered, threatened

or protected species. The Queensland mud crab fishery extends along the entire length of the Queensland coastline, both the east coast and the Gulf. Given the size and habitat variety of the

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fishery, there are a number of protected species occurring in the fishery area. Prominent among these are marine turtles, sea snakes, and dugongs. Interactions with marine turtles are likely to be the most prominent negative interaction. Comments received from Dr Col Limpus, Queensland Parks and Wildlife Service, suggest that between 50 and 100 interactions between turtles and crab pots (from both the mud crab and blue swimmer crab fisheries) are recorded in Queensland annually. The majority of these interactions involve turtle entanglements in pot float lines. Although the potential for entanglement per pot is negligible, the large number of recreational and commercial pots set annually on a statewide basis increases the risk of entanglement. Anecdotal evidence indicates that in Queensland the majority of turtle interactions with crab pot float lines arise from the blue swimmer crab fishery since it operates in habitat more similar to that of marine turtles (in comparison with the mud crab fishery). As criteria 2.2.1 outlined, information from commercial fishers and from QDPI researchers with extensive experience in the mud crab fishery strongly indicates that, beyond the issues discussed above concerning marine turtles, there are few interactions with endangered, threatened or protected species. The fishing gear and methods used further reduces the potential for negative interactions. The views of QDPI are supported by Knuckey, Hay and Russell (pers. comm., 2001, cited in NTDBIRD 2002) in the Northern Territory mud crab fishery ecological assessment: ”[T]here has never been a reported, or sighted negative interaction with threatened, protected or endangered species…”. Accordingly, QDPI has not undertaken a formal assessment of the impacts to endangered, threatened or protected species. Should interactions increase or be found to be more prevalent than currently believed, ongoing monitoring of information available from commercial logbooks and from fishery-independent research will detect such changes. 2.2.3 There is an assessment of the impact of the fishery on threatened ecological

communities. No threatened ecological communities have been identified in the specific area and habitats fished by the Queensland mud crab fishery. Damage to the surrounding habitat is likely to be minimal. Fishers may damage mangroves when setting the pots amongst the mangroves or may damage the in-stream substrate with the boat or propellers if they go into shallow water. However, these impacts are associated more with estuarine and inshore boating and fishing generally than mud crabbing specifically. Previously, tacit approval was given to fishers to shade caught crabs with mangrove branches and leaves. In recognition of the potential for detrimental effects to mangrove communities, which provide key habitat for both terrestrial and marine communities, this provision has been removed from the Queensland management arrangements. A more detailed examination of the impacts to the ecosystem in general is provided under Principle 2 – Objective 3.

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Management responses 2.2.4 There are measures in place to avoid capture and/or mortality of endangered

threatened or protected species. and 2.2.5 There are measures in place to avoid impact on threatened ecological

communities. and 2.2.6 The management response, considering uncertainties in the assessment and

precautionary management actions, has a high chance of achieving the objective.

The low actual and potential negative impacts of the mud crab fishery on endangered, threatened or protected species, and on their associated habitats and ecological communities reduces the need for specific management measures. In saying this, QDPI fully recognises and endorses that regular monitoring is still required to minimise the potential risk of negative impacts. Such monitoring is undertaken directly via the commercial logbook program and the forthcoming Species of Conservation Interest logbook (SCOl); and the fishery-independent LTMP. Indirectly, the monitoring is supported by the modifications to the RFISH survey estimates and the current NTDBIRD-FRDC-QDPI Mud Crab Project. Inclusion of and consultation with all stakeholders in managing the fishery, via the CRABMAC process, provides a further avenue for any negative impacts to be raised, discussed and acted upon. To illustrate, since the establishment of CrabMAC there has been a standing item on the CrabMAC meeting agenda for members to report any interactions with turtles that may have come to their attention. This is particularly relevant for the commercial, recreational, conservation and scientific members. Another example of CrabMAC supporting action that benefits the broader marine ecosystem is the removal of the previous consent given to fishers to shade their mud crab catch with mangrove branches and leaves.

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Objective 3. The fishery is conducted, in a manner that minimises the impact of fishing operations on the ecosystem generally. Information requirements 2.3.1 Information appropriate for the analysis in 2.3.2 is collated and/or collected

covering the fisheries impact on the ecosystem and environment generally. All available information indicates that the impact of the fishery on the ecosystem generally is likely to be low. The information base includes:

• commercial fishery logbooks including endangered, threatened and protected species reporting;

• fishery-independent data derived through the Long-Term Monitoring Program, the NTDBIRD-FRDC-QDPI Mud Crab Project and other fishery independent research (e.g. Tropical Resource Assessment Program); and,

• comments from commercial and recreational fishers, and scientific researchers in Queensland and interstate.

However, QFS recognises that more rigorous research on the ecosystem generally is required to confirm the informal assessment. As has been mentioned previously, the collaborative NTDBIRD-FRDC-QDPI Mud Crab Project will provide key habitat information for the Northern Australian mud crab fishery and a more accurate assessment of the mud crab stock itself. NTDBIRD (2002) has suggested (subject to resource availability) that a comparative assessment of fished and unfished areas may be undertaken as an extension to the above project. Such a comparative assessment would allow both research partners, Queensland and the Northern Territory, to better quantify any ecosystem impacts that may arise from the mud crab fishery. Assessment 2.3.2 Information is collected and a risk analysis, appropriate to the scale of the fishery and its potential impacts, is conducted into the susceptibility of each of the following ecosystem components to the fishery.

1 Impacts on ecological communities • Benthic communities • Ecologically related, associated or dependent species • Water column communities

2 Impacts on food chains

• Structure • Productivity/flows

3 Impacts on the physical environment

• Physical habitat • Water quality

No formal assessment or risk analysis has been conducted on impacts of the mud crab fishery to ecological communities, food chains or the physical environment. This is

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primarily due to consensus among fishers, researchers and managers in Queensland, and interstate (see NTDBIRD 2002), that any general ecosystem impacts are minimal. Mud crab pots are generally constructed of wire mesh though hard plastic and trawl mesh pots are also used in the recreational fishery, as are mesh dillies (see Figure 1). These relatively lightweight and stable apparatus are assumed to impart little physical impact to the in-stream or foreshore habitat, or to the associated benthic communities in which they are set. Daily pot checks and frequent pot repositioning, which is the standard practice in both the commercial and recreational fisheries, further reduces the potential for long-term impacts to benthic habitats and communities, or to water quality in general. The Queensland Fisheries Act 1994 provides further protection to mud crab habitats and associated or dependent communities. Under the Act all marine plants, including mangroves and seagrasses, are protected. This provision affords important protection to the general ecosystem associated with the mud crab fishery as the typical habitat for mud crabs is within or on the fringes of mangrove forests (Hill 1982; QFMA 1999). All mud crab burrows are also protected under the Act. As pots are set on the creek/stream bottom and are quickly hauled to the surface when checking, the potential for impacts to water column communities is negligible. Bycatch from the mud crab fishery is unlikely to have a significant impact on ecosystem structure and function. Comments from commercial fishers and scientific researchers indicate that only a small quantity of bycatch is taken, and that which is has high survivability upon release. Preliminary bycatch results obtained by QDPI through the Long-Term Monitoring Program and the NTDBIRD-FRDC-QDPI Mud Crab Project supports these general observations (Helmke, pers. comm. 2002; Bailey, pers. comm. 2002). The main potential threat to the ecosystem generally is the large annual take of legal size, adult mud crabs. As outlined previously (1.1.1 – 1.1.9), the mud crab catch itself is considered sustainable for several reasons. First, there are strengths in the mud crab life cycle which give high resilience to fishing pressure, including very high fecundity, a protracted spawning period, rapid growth and early sexual maturation (Williams 2002). Walters (1996), a stock assessment and management expert commissioned to review the sustainable use of Northern Territory fishery resources, suggested it is possible to harvest the entire legal-sized component of a mud crab population without crashing the fishery due to the rapid growth of smaller crabs into legal-sized crabs. Second, the management measures in place in the Queensland commercial and recreational fisheries are the most conservative in Australia and ensure that mud crab populations are sustainable. Primarily, the 15cm carapace width (CW) minimum legal size for male crabs, which allows a sufficient proportion to reach reproductive size before capture, and the prohibition on female crabs, which ensures effective annual spawning and recruitment. The different stages of the mud crab life cycle are involved at different trophic levels in marine food webs. The larval stage, as it is planktonic, forms part of the food source of plankton-eating organisms such as fish and jellyfish. Post-larvae and juveniles are presumed to be eaten by a wide variety of fish species that frequent mangrove areas. As mangrove areas provide nursery habitat for numerous species,

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mud crabs form only one of many prey for these fish species (Fielder and Heasman 1978). Given that current management measures ensure sustainable annual spawning and recruitment, mud crab larvae, post-larvae and juveniles are not considered to be significantly affected by the fishery. Adult mud crabs have fewer predators than the larval and juvenile stages. Large fish, such as barramundi, groper and large cod, sharks, turtles, rays and crocodiles all prey on adult mud crabs. No detrimental effects to these species have been identified despite the increasing annual mud crab catch. Nevertheless, QFS recognises that a more formal risk assessment would provide greater certainty as to the sustainability of ecosystem impacts. At present, a large part of QFS’s research focus concerning the mud crab fishery is the habitat mapping and stock abundance estimation being pursued through the NTDBIRD-FRDC-QDPI Mud Crab Project. This project represents phase one of the three-phase ‘Five-year Research Strategy for Northern Australian Mud Crab Resources’ endorsed by Queensland, Northern Territory and Western Australia at the 1999 National Mud Crab Workshop (Calogeras 2000). As was discussed in criteria 2.1.1 to 2.1.6, the project is also producing valuable initial bycatch results, and may provide some information on the impacts of the adult mud crab catch on the ecosystem generally (NTDBIRD 2002). A comparative assessment of fished and unfished areas, suggested by the Northern Territory as an extension to the project subject to available resources (NTDBIRD 2002), may provide more detailed ecosystem information. The QFS Long-Term Monitoring Program (LTMP) will also provide preliminary information on the potential risk of ecosystem impacts. Species composition and abundance of all bycatch caught in the mud crab LTMP sampling is now recorded, reflecting QFS’s commitment to bycatch and ecosystem sustainability. Furthermore, the barramundi LTMP results will reveal any negative trends in barramundi stocks. As a predator of adult mud crabs, barramundi could serve as a quasi-indicator of potential ecosystem impacts from the mud crab fishery. Should any negative trends be identified, the potential association with the mud crab catch could be investigated. One further issue that may pose a potential risk to the broader marine ecosystem is ghost fishing by lost or abandoned mud crab pots. It is acknowledged that the potential and actual impact of ghost fishing requires further investigation. However, there are a number of relevant factors in the mud crab fishery that must be considered when assessing the risk posed by ghost fishing. Comments from commercial fishers and researchers indicate that a large proportion of commercial fishers are now using the collapsible style pots constructed of plastic/metal support struts surrounded by trawl mesh. Anecdotal evidence from both the northern and southern reaches of the fishery indicates that the support struts on the pots suffer a high degree of wear and tear and must be replaced on a regular basis (approximately twice a season – Wayne Sumpton, Senior Fisheries Biologist, AFFS, February 2003). Furthermore, as has been reported in criteria 2.2.1, turtles and some large fish species such as cod and catfish are known to tear holes in the pot mesh to feed on the baits, crabs and any bycatch that may be trapped. Although variable dependent on local characteristics, the life expectancy of a crab pot that isn’t repaired regularly is quite short (Stirling Peverell, Fisheries Biologist, AFFS, February 2003).

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QDPI researchers involved in the mud crab fishery have also found that pots quickly fill up with debris, for example leaves and mud, particularly in high flow areas. Again, although variable dependent on local characteristics, mud crab pots left unattended for extended periods would become progressively more full with debris and likely would not continue to fish (Stirling Peverell, Fisheries Biologist, AFFS, February 2003). QFS has undertaken research on the severity and duration of ghost fishing impacts for the blue swimmer crab fishery in Moreton Bay (Sumpton et al. 2003). To date, this research has not been extended to the mud crab fishery. Management responses 2.3.3 Management actions are in place to en sure significant damage to ecosystems does not arise from the impacts described in 2.3.1. and 2.3.4 There are decision rules that trigger further management responses when monitoring detects impacts on selected ecosystem indicators beyond a predetermined level, or where action is indicated by application of the precautionary approach. and 2.3.5 The management response, considering uncertainties in the assessment and precautionary management actions, has a high chance of achieving the objective No specific management actions have been implemented and no decision rules linked to indicator species have been developed in relation to impacts to the broader marine ecosystem. All available evidence suggests there is only a minimal impact to the broader marine ecosystem from the mud crab fishery using current gear and at current levels of effort in the commercial, recreational and indigenous sectors. The recording of bycatch information has been incorporated into the Long-Term Monitoring Program with the first results due early- to mid-2003 (Sue Helmke, pers. comm. 2002). Similarly, results from the NTDBIRD-FRDC-QDPI Mud Crab Project will also be available mid- to late-2003 (Hay and Phelan 2002). These results will allow a preliminary assessment of the ecosystem impacts of the mud crab fishery. If actual or potential threats to the broader marine ecosystem are highlighted, QFS, with the assistance of CRABMAC, will develop appropriate management responses as part of the formal management regime for the fishery.

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REFERENCE LIST Andersen, L. and Norton, J. 2001. Port Curtis mud crab shell disease - nature distribution and management. FRDC Project No. 98/210. Central Queensland University, Gladstone, 115p. Bartleet, A., Kennelly, S. and Brayford, H. 1993. Proceedings of the Mud Crab Workshop, Terrigal NSW, 21st September 1993. NSW Fisheries. Brown, I.W. 1993. Mangrove Crabs, pp 609-42 in A. Wright and L. Hill (eds) Nearshore Marine Resources of the South Pacific. Institute of Pacific Studies (Suva), Forum Fisheries Agency (Honiara) and the International Centre for Ocean Development (Canada), 710p. Calogeras, C. 2000. Mud Crab Workshop. Towards a National Strategy for Mud Crab Research. Fisheries Report No. 48. Northern Territory Department of Primary Industries. COAG 1992. National Strategy for Ecologically Sustainable Development. Australian Government Publishing Service, Canberra, 128p. Coates, M. 1993. Should female mud crabs be protected? Report to the Queensland Commercial Fishermen’s Organisation (Rockhampton branch), 10p. de Vries, C., Danaher, K. and Dunning, M.C. 2002. Methods for monitoring the abundance and habitat for northern Australian mud crab Scylla serrata. Milestone Report. Objective 1: Habitat mapping. Report to the NT Department of Business, Industry and Rural Development (NTDBIRD) and the Fisheries Research and Development Corporation (FRDC). Queensland Department of Primary Industries, 28p. Evans, L. (ed) 1995. Proceedings of the Mud Crab Workshop, Broome WA, 27th October 1995. Aquatic Science Research Unit, Muresk Institute of Agriculture, Curtin University of Technology, 74p. Fielder, D.F. and Heasmann, M.P. 1978. The Mud Crab. Queensland Museum Booklet 11, 15p. Gopurenko, D., Hughes, J.M. and Keenan, C.P. 1999. Mitochondrial DNA evidence for rapid colonisation of the Indo-West Pacific by the mud crab Scylla serrata. Marine Biology 134: 227-33. Gopurenko, D. and Hughes, J.M. 2002. Regional patterns of genetic structure among Australian populations of the mud crab Scylla serrata (Crustacea, Decapoda): evidence from mitochondrial DNA. Marine and Freshwater Research 53: 849-57. Gould, S.F., Peverell, S.C., Helmke, S.A. and Gribble, N.A. 2001. Status of Gulf of Carpentaria mud crab stocks: abundance estimates for Albatross Bay, Weipa. Project Report QO01003. Queensland Department of Primary Industries, 23p.

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