River Welland fish pass update and monitoring report...
Transcript of River Welland fish pass update and monitoring report...
1 River Welland Monitoring Report
River Welland fish pass update and
monitoring report 2014
Tallington fish pass in early June after heavy rainfall.
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Executive Summary
Fish and eel passes were installed during 2012/13 on two previously impassable
structures, Tallington Gauging Weir and Duddington Mill Weir.
To understand how effective the passes have been, underwater video monitoring
was undertaken during the spring and summer of 2014. The monitoring has shown
that the passes at Tallington and Duddington have provided effective fish passage
over previously unassailable barriers. Despite the fact that the monitoring was
undertaken outside of the peak migration periods for the main species in the River
Welland, the results clearly show a range of species can utilise the passes in both an
upstream and downstream direction.
Species such as eels whose survival relies on the ability to freely migrate in and out
of rivers into saline water are now using the passes regularly. This is vital to
maintaining and increasing their numbers in the Welland system and beyond.
Resident fish species such as chub and trout are also using the passes to move
between river reaches and make best use of their now increased habitat range. This
will greatly improve the resilience of fish stocks in the future on a river system that
has suffered population declines.
These results are encouraging given the short time the passes have been in place.
As fish behaviour adapts a higher use of the passes by resident species will become
more common.
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Introduction
The aim of this report is to:
Summarise the progress to date in terms of making existing obstructions
passable to fish and eels;
Assess the recent monitoring results from two newly installed fish passes on
the River Welland; Tallington fish pass in Lincolnshire (pictured below) and
Duddington fish pass in Northamptonshire; and
Identify any future monitoring plans on the River Welland.
Background
The River Welland has been heavily modified throughout the centuries for
navigation, water resource and flood defence purposes. These modifications saw
numerous locks, sluices and weirs put in place within the river to alter, retain and
change its flows and depths. When structures like these were installed then there is
an instant change in the ability of a fish population to act naturally within their
lifecycle characteristics. Fish migrate for a number of reasons, to spawn successfully
in particular habitat conditions, to find food, to avoid drought and to access refuge
and shelter. The building of one structure can prevent successful completion of fish
life cycles. Anadromous fish species such as sea trout and salmon require the ability
to swim up freshwater rivers to spawn. Catadromous species such as eels require
the opposite, the ability to migrate out to the Atlantic to spawn and for their juveniles
to be able to ascend the rivers again upon their arrival at the coast. Resident species
in the river such as cyprinids (e.g. roach and dace) need the ability to move to freely
around the river as part of their lifecycle characteristics. The key migration periods
for fish species in the Welland catchment is as follows:
Eel upstream migration – April to September inclusive.
Eel downstream migration - October to December inclusive.
Coarse fish migration - March to June inclusive.
Brown trout migration - September to November inclusive.
Sea trout migration – All Year (NB we will be narrowing down the critical
period for sea trout with on-going monitoring)
Lamprey migration - September – March inclusive.
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Existing Obstructions to fish and eel passage
A number of key obstructions to fish passage were identified in the Welland
catchment in 2011 as part of a catchment scale approach to improving the ecological
status of the river. These obstructions comprise a mixture of weirs, locks and sluices
which are shown on Figure 1 below.
The aim has been to investigate and provide, if required, fish pass solutions for these
obstructions. These fish passes are either delivered as standalone projects or tied
into the refurbishment of these obstructions as part of maintenance schemes. As
part of the catchment scale approach, these fish pass solutions compliment the
wider ongoing works in the catchment. This includes measures to control diffuse /
point source pollution and in channel works to enhance degraded river habitats. It is
important to recognise that making these obstructions passable is not the total
solution to improving fish stocks and the condition of the river so this holistic
catchment approach is essential.
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Figure 1: Key Obstructions on the River Welland
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Progress to Date
Of the obstructions identified in Figure 1, the following progress has been made with
regard to providing fish passage:
Table 1: Progress on fish pass design and construction
Obstruction Watercourse Asset Owner
Design Complete / Planned
Construction Complete / Planned
Surfleet Sluice River Glen EA Design underway: Automation and soft close doors
Construction planned in 2015/16
Fulney Lock River Welland EA Design complete: Installation of penstock in tidal door
Construction planned in 2015
Marsh Road Sluice
Coronation Channel
EA Optioneering complete but no design undertaken
No construction planned. Will be considered alongside any refurbishment
Kates Bridge Weir
River Glen EA No design work to date
No construction planned. Will be considered alongside any refurbishment
Nine Bridges Weir
Maxey Cut IDB Design complete: extra stop log required in weir but this requires weir to first be repaired
Construction date to be confirmed with asset owner
Piled Weir Maxey Cut EA Design complete: installation of notch and adherent nappe
Construction completed in 2014
Rock Ramp Maxey Cut EA Design complete: Installation of pool pass, adherent nappe and eel pass
Construction completed in 2014
Timber Weir Maxey Cut EA Design complete: installation of notch and adherent nappe
Construction completed in 2014
Lolham Road Bridge
Maxey Cut PCC Design complete: installation of eel tiles
Construction planned alongside refurbishment. No refurbishment planned in the short term
Tallington Weir Maxey Cut EA Design complete: installation of larinier, pre barrage and eel pass
Construction completed in 2014
Newstead Mill River Gwash EA Design complete: construction of new bypass channel
Construction planned in 2015
Borderville Weir
River Gwash Private Design complete: removal of adjacent sluice to reconnect bypass
Construction completed in 2013
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Obstruction Watercourse Asset Owner
Design Complete / Planned
Construction Complete / Planned
Belmesthorpe Weir
River Gwash EA Design complete: installation of low cost baffles and eel pass
Construction completed in 2015
Hudds Mill River Welland EA Design complete: installation of larinier and eel pass
No construction planned. Will be considered alongside any refurbishment
Tinwell Weir River Welland EA Design complete: installation of bypass channel and larinier
No construction planned. Will be considered alongside any refurbishment
Fosters Bridge Weir
River Welland EA Design complete: installation of pre barrage and eel pass
Construction completed in 2013
Duddington Weir
River Welland EA Design complete: installation of pool travers pass and eel pass
Construction completed in 2013
Barrowden Weir
River Welland EA Design complete: installation of larinier and eel pass
No construction planned. Will be considered alongside any refurbishment
Seaton Weir River Welland EA Design complete: rock ramp
Construction planned in 2015
Gretton Weir River Welland EA Design complete: Bypass and larinier
No construction planned. Will be considered alongside any refurbishment
Ashley Weir River Welland EA Design complete: installation of pre barrage and eel pass
Construction completed in 2013
Stonton Weir Stonton Brook EA Design complete: weir removal and rock ramp
Construction completed in 2013
Langton Brook Langton Brook
EA Design complete: notch weir and pre barrage
Construction completed in 2013
Market Harborough Weir 1
River Welland EA Design complete: partial weir removal
Construction completed in 2013
Market Harborough Weir 2
River Welland EA Design complete: partial weir removal
Construction completed in 2013
In summary 13 or the 25 obstructions listed in the table above have now been
constructed with several more planned. Other passes that were already in place in
the Welland catchment before 2011 include Low Locks, High Locks, Wherry’s Mill,
Fletland Mill, and Greatford Cottages. These are currently being investigated by the
Fisheries, Biodiversity and Geomorphology team to ensure they are working
efficiently and being maintained as required.
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Monitoring the success and efficiency of installed passes at Tallington and
Duddington
The fish and eel passes at Duddington and Tallington were constructed in 2012 / 13
to comply with the Eel Regulations 2009, the Salmon and Freshwater Fisheries Act
1975, and the Water Framework Directive. The fish pass at Duddington comprises a
5 m wide; 45m long pool traverse type fish pass. The eel pass at this site comprises
3 bristle type troughs, one extending the length of the pool traverse fish pass and the
other 2 extending over the new weir sills. The fish pass at Tallington comprises a
0.6m wide, 7m long larinier type pass with a timber pre barrage downstream.
Alongside this is a vertical brush eel pass.
Their locations are shown on the below; Tallington fish pass represents the first large
barrier upstream for a migrating sea trout which has gone beyond the tidal locks and
sluices at Spalding and has made its way up the Maxey Cut.
Figure 2: Location map
Results from 2014 are being used to help influence future monitoring work on both
Tallington and Duddington fish passes and also future fish pass use. Long term
monitoring of the River Welland will involve numerous techniques to assess how fish
move around the river including the use of sonar, fish tagging telemetry projects,
electric fishing and catch returns from anglers.
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Both passes were monitored in 2014 using high frequency multibeam imaging sonar.
At Tallington, an ARIS 3000 (adaptive resolution imaging sonar) was lowered down
inside its deployment tube to face the exit of the larinier pass imaging upstream at
right angles to the exit of the pass. At Duddington, a DIDSON 1800 (dual frequency
identification sonar) was lowered down inside its deployment tube to image the final
upstream slot exit of the pass. Pictures of the sonar locations are detailed below,
along with a table of their monitoring properties in relation to this work.
The sonar’s used for monitoring make video images from sound waves; they give
back a bird’s eye perspective of the area of water being imaged so the viewer looks
down on top of the fish pass. The main advantage for using the sonar’s is their ability
to see through extremely turbid water and darkness. This allows for video recording
to take place in all conditions. The data was recorded to external hard drives then
processed in two different methods on ARISfish software. Firstly using echogram
mode which displays the sound wave signals in a visual form against time, this
allows for any fish tracks within the display that are left by fish to be isolated quickly
and logged. Second is an automated programme within the sonar software called
CSOT (Contagious Samples Over Threshold). This allows signals of a certain
strength and size to be found automatically according to set parameters. Once fish
movements were found within the data all were measured to end of tail length using
the fish measuring tool within ARISfish. Fork length measurement was possible but
due to the perspective of the images full tail length measurements were more
reliable. Examples of the each processing technique are shown below.
Table 2: Processing techniques
Parameter Tallington - ARIS 3000 Duddington - DIDSON 1800
Range imaged 0.7 - 2.5m 1 - 5m
Frequency imaged 3.0 MHz 1.8 MHz
Field of view 30º x 14º 29º x 14º
Recording style Continuous 24/7 Continuous 24/7
Power supply Mains 240v Mains 240v
Recorded to External hard drive External hard drive
Time frame 10 minute recording 10 minute recording
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Tallington results
Figure 3: Tallington weir Location map
The Larinier pass allows fish to swim up the Maxey Cut and successfully move into
the reach above, opening up another 6km of river towards Stamford. This would
have previously been not passable by fish since the weir was put in place at the
same time that the Maxey Cut was dug in 1955. The pass also ensures safe
downstream passage.
Importantly this pass improves access into the River Gwash that joins the Welland
downstream of Stamford. The Gwash holds one of the highest populations of wild
brown trout in the east of England; it provides extremely good habitat for fish and
also good spawning substrate for salmonid species. It is considered that when brown
trout densities reach a high enough level it becomes one of several triggers for
resident fish to start to “run” to sea and become sea trout that will return to the same
river to spawn. Sea trout that have been caught in the Maxey Cut before may have
come from the Gwash but have struggled to return due to barriers like Tallington
Weir. The red line on the map above indicates where the original weir without a pass
sat at the head of the Maxey Cut.
Monitoring began at Tallington in late May 2014 and continued throughout the
summer; exact dates of recordings are tabled below. The sonar was removed on
numerous occasions to keep up with demand for the equipment around the region.
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Table 3: Monitoring period for Tallington
Recording period Total days recorded
20th May - 24th May 2014 4
2nd June - 17th June 2014 19
26th June - 27th June 2014 21
1st July - 14th July 2014 25
28th - 29th July 2014 27
1st August - 17th August 2014 43
Figure 4: Camera (sonar) location in relation to the pass
Exit of fish pass
Camera location
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Figure 5: Sonar visual output
Processing using echogram mode, the software automatically processes the data
into the graphical representation shown above. The grey bar across the top
represents a five minute time period. The track produced by an eel moving
downstream is visible within the section is also highlighted. The user can then
identify tracks left in the echoes made by fish easily.
Figure 6: CSOT outputs
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Processing using CSOT, the software searches for echoes above certain strength
and size parameters set by the user. By subtracting the static background these
echoes can be isolated and then checked whether they are created by passing fish.
The eel seen in the echogram on the previous page generates a spike in the data as
shown above; this segment of footage is automatically extracted and is then
available for analysis.
Sonar’s were positioned at the top of each pass; each was positioned to cover the
full exit dimension of the pass. At Tallington the beam coverage sits exactly between
the bed of the pass and the roof of the pass, any moving object cannot enter or leave
the pass without being detected.
The sonar was located in its guillotine and lowered into position imaging the pass
entrance, the data cable ran back through conduit to the telemetry hut w the
command module and laptop were located. The equipment was checked periodically
to clean the pass, remove any debris and to replace the hard drives used to to
record the data to.
Three dominant species (Pike, eels and trout) were found to be utilising the pass at
Tallington; each can be distinguished within the footage by their body shape and fin
array. Upstream movements were classed when fish appeared from the exit to the
pass and moved successfully away from the pass. Upstream movements were not
recorded if a fish moved into the top of the pass and then turned around and came
back out again, this happened on one occasion. Downstream movements were
recorded as being succesful if fish moved downstream through the pass and did not
return back out of the exit again. The sonar also recorded a large otter heading down
the pass; measuring well over 1m it will have reached maximum size for the species.
A table of the fish species using the pass and when is detailed on the following page.
In total 25 fish used the pass during the time that the sonar was in recording; 11
pike, 10 eels, 3 trout and either 1 dace or a chub (due to the body shape it was
difficult to differentiate between these two species). Given that the monitoring was
undertaken outside of the key migration periods for the fish species in the Welland
these are very encouraging results and show that a range of species can utilise the
pass.
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Table 4: Monitoring results for Tallington
Date Species Upstream Downstream Time
21/05/2014 EEL 740mm 02:40am
21/05/2014 PIKE 560mm 10:40am
21/05/2014 EEL 420mm 22:50pm
22/05/2014 EEL 196mm 00:24am
23/05/2014 PIKE 630mm 11:35am
23/05/2014 PIKE 630mm 12:19pm
23/05/2014 EEL 340mm 12:44pm
02/06/2014 PIKE 440mm 11:35am
02/06/2014 PIKE 565mm 16:20pm
04/06/2014 EEL 520mm 02:35am
04/06/2014 EEL 250mm 23:11pm
05/06/2014 TROUT 345mm 02:30am
06/06/2014 EEL 480mm 04:30am
07/06/2014 TROUT 510mm 02:30am
09/06/2014 PIKE 500mm 09:29am
10/06/2014 PIKE 565mm 05:49am
10/06/2014 PIKE 565mm 05:53am
13/06/2014 PIKE 475mm 09:25am
11/08/2014 PIKE 460mm 15:20pm
12/08/2014 EEL 820mm 08:37am
13/08/2014 TROUT 440mm 10:52am
13/08/2014 EEL 720mm 21:56pm
13/08/2014 DACE/CHUB 230mm 22:54pm
14/08/2014 PIKE 980mm 08:05am
14/08/2014 EEL 563mm 23:25pm
Upstream movment was greater than downstream with 17 fish moving up through
the pass and 8 moving downstream. Usage of the pass was very similar when
comparing day and night movements. 14 fish used the pass during the hours of
daylight and 11 in darkness. Trout and the solitary dace/chub only ascended the
pass, there was no fish filmed from these species heading downstream whereas free
movement of pike and eels both upstream and downstream occured. Monitoring of
the stand alone eel pass that sits adjacent to the main larinier pass is not possible
due to its location. From previous trapping of eels at Tallington Weir in 2009 there
were almost 1000 juveniles caught and relocated upstream of the weir during the
summer. These eels will be taking advantage of the new dedicated eel pass to move
upstream. The larger eels captured by the sonar will be eels that are able to freely
move up the main lariner pass.
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Eel Movements
Figure 7: Recorded eel migrations against flow
Eel movements during the monitoring at Tallington are shown above. It is important
to note that the sonar was not recording throughout the entire time period. Eel
movements during June consisted of fish moving both up and down the pass, these
coud be “residential” movements within the river as eels move around making full
use of their now increased habitat range. Later in the year during August three large
eels all move downstream; these are likely to be mature eels that are starting to
make migratory movements as they leave the river system to swim across the
Atlantic to spawn. Eels moved upstream in flows at a low rate of 1.43 cumecs
(approx Q 35) daily average and downstream in high flows of 11.5 cumecs (approx
Q5) daily average. This flow rate is for the entire weir and not the flow coming down
the fish pass itself but it provides a good indication of realtive flows, the migration
triggers and also was the flow information used to deign the pass itself.
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Pike Movements
Figure 8: Recorded pike migrations against flow
Movement of pike consisted of both usptream and downstream use of the pass. Pike
moved upstream in a range of different flow rates. Upstream movement of pike
occured at a lowest flow rate of 1.35 cumecs (approx Q35) daily average during
August. They were also able to migrate up the pass at a rate of 5.35 cumecs (approx
Q15) daily average during early June.
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Trout Movements
Figure 9: Recorded trout migrations against flow
Trout numbers were low during filming during the summer but given that the peak
migration is during spawning (Typically September to November) this is not
unexpected.. Two fish moved up the weir in June at similar flow rates of 6.44 and
7.06 cumecs (approx Q10) daily average respectively. A fish later in the year during
August went up the pass at a lower rate of 1.59 cumecs (approx Q30) daily average.
Historically sea trout and resident brown trout runs happen slightly later in the year
than when the monitoring stopped as fish move up river to reach spawning gravels in
time for the cooler winter temperatures required for egg survival. Future monitoring
will involve specific monitoring aimed at capturing sea trout migratory movements.
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Duddington Results
Figure 10: Duddington weir Location map
Figure 11: Camera (sonar) location in relation to the pass
Exit of fish pass
Debris boom
Camera location
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The pass at Duddington opens up another 6km of river to migrating fish up to
Barrowden gauging weir. This sluice at Duddington would have been put in place
when the mill was first used; this is the first time that the structure will be passable
for at least a century.
The red line indicates the location of the previous barrier that the old sluice caused.
The Mill channel was also not passable due to the sluice that controls the level there.
The DIDSON was deployed at Duddington upstream to the final exit to the pass. As
shown overleaf the image was aimed along the top of the weir with the exit slot in to
assess fish movements in and out of the pass. Similar to Tallington the entire exit
slot is covered by the sonar so nothing can move in or out without being picked up.
Fish were only counted as having ascended the pass if they swim out without being
picked up heading downstream and having turned around again. Beam dimensions
were set to cover the complete area above the top of the pass, all objects moving
upstream or downstream were imaged.
Data was processed using CSOT at Duddington, the image below shows how this
was carried out. An area above the exit to the slot (green segment) was identified as
a suitable location to detect fish. Parameters when then set to record echoes falling
within this area that achieved set signal strength and size. Objects attaining these
parameters were then outputted for further analysis to see if they were made by
passing fish such as is happening in the screenshot. Filamentous algae can be seen
trailing off the floating debris boom towards the top of the sonar image.
Figure 12: Sonar visual output
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The DIDSON was in for a shorter time period than the ARIS at Tallington. Recording
started in May and finished in early July, it did not record full time due to power
outage at the mill itself that knocked the equipment out until it could be reset and
also when the hard drive became full but could not be changed immediately after this
happened. Fish species ID was difficult at Duddington using the DIDSON on the
image range it was set at, the resolution is not as good as with the ARIS. Pike and
eel are very visible due their elongated body shape and fin array. Other fish using
the pass would either be trout or chub; there are numerous examples of each but to
avoid uncertainty they are recorded as fish.
Table 4: Monitoring results for duddington
Date Species Upstream Downstream Time
09/05/2014 FISH 350mm 13:00pm
10/05/2014 EEL 560mm 16:50pm
11/05/2014 FISH 330mm 22:50pm
14/05/2014 FISH 400mm 15:50pm
17/05/2014 EEL 530mm 12:50pm
20/05/2014 FISH 340mm 00:01am
22/05/2014 FISH 360mm 19:40pm
23/05/2014 FISH 440mm 15:30pm
25/05/2014 FISH 340mm 05:50am
25/05/2014 FISH 300mm 17:20pm
28/05/2014 FISH 410mm 15:20pm
30/05/2014 PIKE 550mm 21:00pm
04/06/2014 EEL 560mm 01:10am
04/06/2014 FISH 340mm 09:20am
13/06/2014 FISH 340mm 14:30pm
18/06/2014 FISH 300mm 18:10pm
20/06/2014 PIKE 620mm 16:45pm
27/06/2014 EEL 560mm 07:20am
Out of a total of 18 movements through the pass 15 were upstream and only three
downstream.15 of the movements were made during the daylight and 3 in darkness.
Chub and trout would have made up the majority of fish movements at Duddington.
Downstream of the pass is a routine electric fishing survey site, results from this site
help to reflect the species of fish that will be using the pass. Trout and chub are
regularly caught in the same size range as the fish seen using the pass. Dace and
roach are not found to 300mm in this section of the river. Pike make upstream
movements on two occasions while eel ascend and descend through the pass.
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Figure 13: Recorded fish migrations (excluding eels) against flow
Flow rate data was taken from the nearest gauging weir to Duddington which is
approximately 6km upstream of the pass at Barrowden, therefore flow rates will differ
to those experienced at Duddington but will give some indication on fish movement
in what kind of state the river was in. The graph above represents all fish species
movements against flow rates including pike but no eels. Fish utilised the pass in a
wide range of flows, from lower flows of 0.674 cumecs (approx Q60) daily average in
July through to a higher rate of 8.64 cumecs (approx Q3) daily average.
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Figure 14: Recorded eel migrations against flow
Eels moved through the main pass at lower flow rates than other fish species using
it. All upstream eel movements were made in flow conditions of less than 2 cumecs
(approx Q30). Due to the small numbers no firm conclusions should be drawn about
the ability to pass at higher flow rates. There are numerous options for migrating eels
at Duddington Sluice, in addition to the main pool traverse pass which will cater for
larger eels, there are three dedicated eel passes on site which were not monitored.
These three bristle type eel pass operate over a wide range of flows and are known
to be passable even under extremely high flow conditions.
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Conclusions
Both Tallington and Duddington have provided effective fish passage over previously
unassailable barriers. Despite the fact that the monitoring was undertaken outside of
the peak migration periods for the main species in the River Welland, the result
clearly show a range of species can utilise the passes in both an upstream and
downstream direction.
Species such as eels whose survival relies on the ability to freely migrate in and out
of rivers into saline water are now using the passes regularly. This is vital to
maintaining and increasing their numbers in the Welland system and beyond.
Resident fish species such as chub and trout are also using the passes to move
between river reaches and make best use of their now increased habitat range. This
will greatly improve the resilience of fish stocks in the future on a river system that
has suffered population declines. These results are encouraging given the short time
the passes have been in place. As fish behaviour adapts a higher use of the passes
by resident species will become more common.
Future monitoring plans for the River Welland
Below is a list of the sites that we aim to monitor in the future to determine their
existing passability or to determine the effectiveness of any installed fish pass
solution.
Priority Monitoring for the Sonar (ARIS and Didson) equipment
Maxey Road Bridge eel pass – Further monitoring to determine if the installed eel
pass is working effectively.
Fulney Lock – Further monitoring will be required when the fish pass solution is
installed to confirm its works effectively.
Secondary Priority Monitoring for the Sonar (ARIS and Didson) equipment
Sea trout passage monitoring – Further monitoring of key locations such as
Tallington fish pass to better understand the migratory behaviour of salmonids, in
particular sea trout.
Routine monitoring
In addition to the use of the ARIS and Didson cameras, long term and routine
monitoring of the River Welland will involve numerous techniques to assess how fish
move around the river including the use of sonar, fish tagging telemetry projects,
electric fishing and catch returns from anglers.