Fisheries of the Mekong:Death by a 1000 Cuts or

Just Another Day at the OfficeVu Vi An, Ian G. Cowx,

With support from Kaviphone Phouthavong, Martin Mallen Cooper, Bun Peng,

So Nam, Apiradee Hanpongkittikul

Content:

1. Introduction

2.Trend of fisheries in the Mekong Delta

3.Pressures on the fisheries

4.Opportunities and mitigation

1. Introduction:

− Total yield in the LMB: over 2.5 million tons (19% of OAAs): Thailand: 36%; Viet Nam: 33%; Cambodia: 23%; and Laos: 8%. Total value: about US$6.5 billion/year.

− Per capita consumption average: about 33.7kg/person/year(VN: 39kg; Cam: 36.8kg; Thailand: 29kg; Laos: 28.6kg).

− Fish diversity: 800 – 1200 species with 30+ of high commercial importance.

− At least 7 giant fish: Mekong giant catfish (P. gigas), giant pangasius (P. sanitwongsei), giant barb (C. siamensis), striped barb (P. jullieni) + Mekong dolphin (O. brevirostris)…

(Hortle, 2007; Hogan, 2011)

1. Introduction:

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Vietnamese Mekong Delta: Tan Chau station

Up to 50%

Concentration of fish in permanent water bodies

Adults movement + Drift of larvae to feeding areas on the flooded areas

Movement to dry season refuges, and dispersal

DRY Season:FLOOD Season:

- White fish (undertaking long distance migrations): 36% of capture;

- Black fish (floodplain resident fish, limited lateral migrations): 50%of capture;

- Grey fish: 14 % of capture.

− Fish migtate all seasons of year.

1. Introduction:

2. Trend of fisheries in the Mekong Delta:Fishing habitats (gillnetting) vs Flooding scheme:− Mainstream : 52%− Tribitary : 24%− Flooded rice field : 24%

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2. Trend of fisheries in the Mekong Delta:- Statistics (capture only):

Total yield: 1,040,759 tMarine:

Fish: 653,600 tOthers: 263,184 t

Inland : 124,626 t

- 67% of households in An Giang province participate in fishing, only 7% are full time fishers.

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(Sjorslev et al., 2001)

Inland: decline 34%or 2.83%/year.

2. Trend of fisheries in the Mekong Delta:- Fishers' catch monitoring program (FP/MRC): 2007 – 2014

Average daily catch: 5.45kg/day/fisher gillnet.

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2. Trend of fisheries in the Mekong Delta:

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- Fishers' catch monitoring program (FP/MRC): 2007 – 2014Average daily catch: 5.45kg/day/fisher gill net.

2009

2. Trend of fisheries in the Mekong Delta:2. Trend of fisheries in the Mekong Delta:- Fishers’ catch monitoring program (FP/MRC): 2007 – 2014

Decline: 8.5kg/day (2007) to 6.4kg/day (2014).

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3. Pressures on the fisheries:Major threats to inland fisheries include:

• Over-fishing + destructive fishing methods

• In-channel barriers (Blocking of fish migration routes)

• Land use changes (habitat loss)

• Industrial and urban pollution

• Urbanisation • Agricultural pollution: pesticides

• Run-of-river abstractions • Mining pollution• Irrigation • Sediment mining• Impoundments • Climate change• Aquaculture linked to

invasive species• Hydrological changes (e.g.

timing and extent of flooding)• Flood mitigation measure • Hydropower

3. Pressures on the fisheries:

0 50 100 150 200 250 300 350

Alien speciesCatching spawners

Climate changeWeak enforcementPopulation growth

Fishing pressure in upstreamPollution

Habitat lossPesticide

HydrologyCatching small fishes

Dyke constructionMore fishersIllegal gears

Frequency (# fishers)

34.5%

31.7%

11.4%

6.6%

4.8%

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3.4%

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Fishers’ perception:

3. Pressures on the fisheries:Illegal gears in the MD:

- Fishing gears: >120 gear types: small and simple: Traps; Gillnetting; Hook and lines, Towing/ dragging; Castnet, Scooping, Collection by hand, Liftnet; Bagnet …

- Illegal gears: Fishing with electricity and chemicals; Gears with small mesh-size.

Motobyke taxi

0.09%

Aquaculture1.42% Small

business2.46%

Fishing only

22.44%

Labor28.03%

Agricultural activities45.55%

Fishers’ likelihoods:

3. Pressures on the fisheries:

% Catch of Exotic Species:

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Including 9 exotic species: Pterygoplichthys disjunctivus, Colossoma macropomum, Oreochromis sp., Hypophthalmichthys molitrix, Clarias gariepinus, Labeo rohita, Cyprinus carpio, Ctenopharyngodon idella, Hypophthalmichthys nobilis.

Exotic species: Fishers’s cacth monitoring program FP/MRC

3. Pressures on the fisheries:Habitat Loss in the MD: Rice…

Vo Tong Xuan (1975) Wyatt et al. (2012)

Rice farming: Change from Floating rice (6 months/crop , ~2tons/ha/ crop, 1 crop/year only, planting during flooding season) to TN rice –“God of agriculture rice” - (3 months/crop, 5-7 tons/ha/crop, up to 3 crops/year, planting in any season).

1975: Floating rice dominated2012: High yield rice +

Intensive

3. Pressures on the fisheries:

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3rd rice crop:

Habitat Loss in the MD: Rice…

1st rice crop: plant earlier by pumping water out…

3. Pressures on the fisheries:

Inland fish yield & Rice farming areas:

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Inland capture yield

Rice farming area

Negative relationship: p<0.005

Habitat Loss in the MD: Rice…

3. Pressures on the fisheries:Water control structure:• Every dot is a registered

water control structure.• Loss of connectivity = loss

of productivity in floodplain/riverine fisheries.

The MRC water structures map

JICA/MARD’s project: in 7 coastal provinces. Structural: Saline intrusion prevention sluice gate contruction; Seashore protection and improvement. Non-Structural: Cropping calendar adjustment and improvement….

3. Pressures on the fisheries:Hydropower dams:9 planned dams on LMB

(mainstream) – two under construction.

23 existed dams (> 20 MW) on tributaries.

Many more tributary dams are projected or under construction.

- Cambodia: 20 projects (1 Ope; 1 Und; 0 Lic; 18 Plan).

- Laos: 100 projects (21 Ope; 25Und; 16 Lic; 38Plan).

- Thailand: 7 Ope prjects.- Viet Nam: 15 projects (13 Ope; 1 Und;

0 Lic; 1 Plan). Niel et al. (2014)

3. Pressures on the fisheries:Linkage Between Drivers and Impacts:

Hydropower Projects Other exogenous factors

Changes in River Flows, Sediment Transport, and

Water Quality

Obstructions in Fish Migration Routes &Habitat Connectivity

Changes in Fish Habitat Quality, Quantity, &

Productivity

Fisheries Impacts

4. Opportunities and mitigation:Fisheries’ characteristics:

Inland Fisheries Marine FisheriesSmall-scale gears Large commercial gearsInformal Formal (e.g. licenced) Dispersed, often hidden by geography/vegetation

Visible, large gears at open sea

Landings dispersed and informal

Landing centralized and visible

Part-time fishing dominates (e.g. mixed farming/fishing lifestyles on river floodplains)

Professional fishing dominates, i.e. very few part-time fishers

Most catch consumed domestically

Most is exported out of the community of capture

Many people participate Few people participate

Modified from: FAO RAP Publication 2002/11

4. Opportunities and mitigation:Mitigation measures:

Mitigation measures to ameliorate likely impacts focus on:

• in-take and outfall locations;

• fish passage facilities – upstream and downstream,

• ‘Friendly’ turbine design;

• measures to ameliorate the potential impact of depleted reaches – allocation of flows;

• replacement of lost fisheries – aquaculture and stocking;

• need habitat connectivity to complete fish life cycle;

• fish friendly irrigation scheme.

Thank youEspecially to AFS

and SEAFDEC