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.


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.


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.


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.


Figure 1: Key Obstructions on the River Welland


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


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


Timber Weir Maxey Cut EA Design complete: installation of notch and adherent nappe


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


Newstead Mill River Gwash EA Design complete: construction of new bypass channel


Borderville Weir

River Gwash Private Design complete: removal of adjacent sluice to reconnect bypass



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


Hudds Mill River Welland EA Design complete: installation of larinier and eel pass


Tinwell Weir River Welland EA Design complete: installation of bypass channel and larinier


Fosters Bridge Weir

River Welland EA Design complete: installation of pre barrage and eel pass


Duddington Weir

River Welland EA Design complete: installation of pool travers pass and eel pass


Barrowden Weir

River Welland EA Design complete: installation of larinier and eel pass


Seaton Weir River Welland EA Design complete: rock ramp


Gretton Weir River Welland EA Design complete: Bypass and larinier


Ashley Weir River Welland EA Design complete: installation of pre barrage and eel pass


Stonton Weir Stonton Brook EA Design complete: weir removal and rock ramp


Langton Brook Langton Brook

EA Design complete: notch weir and pre barrage


Market Harborough Weir 1

River Welland EA Design complete: partial weir removal


Market Harborough Weir 2

River Welland EA Design complete: partial weir removal


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.


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.


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


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.


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


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


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.


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.


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


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


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.


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.

river welland fish pass update and monitoring report...

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