River Welland fish pass update and monitoring report 2014

Transcription

1 River Welland fish pass update and monitoring report 2014 Tallington fish pass in early June after heavy rainfall. 1

2 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 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. 2

3 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. 3

4 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. 4

5 Figure 1: Key Obstructions on the River Welland 5

6 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 Surfleet Sluice River Glen EA Design underway: Automation and soft close doors Fulney Lock River Welland EA Design complete: Installation of penstock in tidal door Marsh Road Coronation EA Optioneering Sluice Channel complete but no design undertaken Kates Bridge Weir Nine Bridges Weir River Glen EA No design work to date Maxey Cut IDB Design complete: extra stop log required in weir but this requires weir to first be repaired Piled Weir Maxey Cut EA Design complete: installation of notch and adherent nappe 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 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 Borderville Weir bypass channel River Gwash Private Design complete: removal of adjacent sluice to reconnect bypass Construction Complete / Planned Construction planned in 2015/16 Construction planned in 2015 No construction planned. Will be considered alongside any refurbishment No construction planned. Will be considered alongside any refurbishment Construction date to be confirmed with asset owner in 2014 in 2014 in 2014 Construction planned alongside refurbishment. No refurbishment planned in the short term in 2014 Construction planned in 2015 in

7 Obstruction Watercourse Asset Owner Design Complete / Planned Belmesthorpe River Gwash EA Design complete: Weir 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 Duddington Weir Barrowden Weir River Welland EA Design complete: installation of pre barrage and eel pass River Welland EA Design complete: installation of pool travers pass and eel pass 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 Langton Brook Market Harborough Weir 1 Market Harborough Weir 2 Langton Brook ramp EA Design complete: notch weir and pre barrage River Welland EA Design complete: partial weir removal River Welland EA Design complete: partial weir removal Construction Complete / Planned in 2015 No construction planned. Will be considered alongside any refurbishment No construction planned. Will be considered alongside any refurbishment in 2013 in 2013 No construction planned. Will be considered alongside any refurbishment Construction planned in 2015 No construction planned. Will be considered alongside any refurbishment in 2013 in 2013 in 2013 in 2013 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. 7

8 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. 8

9 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 m 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 9

10 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 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. 10

11 Table 3: Monitoring period for Tallington Recording period Total days recorded 20 th May - 24 th May nd June - 17 th June th June - 27 th June st July - 14 th July th - 29 th July st August - 17 th August Figure 4: Camera (sonar) location in relation to the pass Exit of fish pass Camera location 11

12 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 12

13 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. 13

14 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. 14

15 10/05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/ /08/ /08/2014 Flow (Cumecs) No of movements Eel Movements Figure 7: Recorded eel migrations against flow Date 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. 15

16 10/05/20 17/05/20 24/05/20 31/05/20 07/06/20 14/06/20 21/06/20 28/06/20 05/07/20 12/07/20 19/07/20 26/07/20 02/08/20 09/08/20 16/08/20 Flow (cumecs) No of movement Pike Movements Figure 8: Recorded pike migrations against flow Date 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. 16

17 10/05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/ /08/ /08/2014 Flow (cumecs) No of movements Trout Movements Figure 9: Recorded trout migrations against flow Date 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. 17

18 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 18

19 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 19

20 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. 20

21 10/05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /07/2014 Flow (cumecs) No of movements Figure 13: Recorded fish migrations (excluding eels) against flow Date 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 cumecs (approx Q60) daily average in July through to a higher rate of 8.64 cumecs (approx Q3) daily average. 21

22 10/05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /07/2014 Flow (cumecs) No of movements 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. 22

23 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. 23