Fisheries Monitoring of the Ribble Catchment

Transcription

1 Fisheries Monitoring of the Ribble Catchment The Ribble Rivers Trust Paul Peters, Fisheries Scientist Ribble Rivers Trust C/o Hanson Cement Ribblesdale Works Clitheroe Lancashire BB7 4QF Tel:

2 Contents Acknowledgements... 2 Executive Summary... 2 Introduction... 3 Methodology... 4 Results... 6 Species Summaries Brown Trout Salmon Coarse Species Grayling Eel Crayfish Conclusions Recommendations References Appendices Appendix A Appendix B

3 Acknowledgements Thanks are offered to the following researchers, staff, and volunteers whose help and continued enthusiasm has proved invaluable during the annual survey programme; Gareth Jones (RRT), Susie Elcock (Seasonal Survey Assistant), Ruth Pengelly (Seasonal Survey Assistant), Mike Forty (RRT), Abigail Powel (Craven College), Rosie Law (West Cumbria RT), Alistair Rollinson (York University), Matthew Bowater (Clitheroe Grammar), Eleanor Graham (Clitheroe Grammar), Joseph Rodgers (Newcastle University), Ellie Brown (RRT), Melanie Hartley (Wyre RT), Steve Johnson (Local Volunteer), Vince Edmondson (RRT). Executive Summary Considering horrendous flood events in 2015 prior to our ninth year of fisheries surveys, salmonids have fared well, however their downward population trend continues. Summary of the observations from summer 2016: - The survival of fry and ova would be low owing to the flood extremes of November 2015 January In follow up to the spring run Atlantic salmon (Salmo salar) tracking study, main stem fish surveys ( ) confirmed the main river s importance to the Ribble catchment s population. This year, reduced densities of salmon were found along the main stem Ribble. Coarse species have prospered; 2016 was officially the Year of the Grayling: 12 fry/parr were captured across six sites within the Hodder/Mid-Ribble areas during the summer. This observation compares with just three over the previous eight years. Downstream movements of signal crayfish in Trawden brook and Long Preston beck pose a rising threat to the sustainability of the Ribble salmon. Signal crayfish populations are advancing where salmon are typically most successful in rearing (Long Preston) and at the limits of their distribution along the Calder. Six fish rescues in support of in channel works were delivered this year saving approximately 4,000 individuals across six species. This year, eight new sites were surveyed to provide pre-works ecological baseline for realising the benefits that the Ribble Life Together project will (hopefully) bring. Two engagement electrofishing days were undertaken as part of the Ribble Life Together project, showcasing electrofishing, Riverfly monitoring and a river walk to 20 students from Myerscough and Burnley college. 2

4 Introduction As a long-term monitoring programme the objective is to identify trends, failures and successes, and opportunities for new works. The 2016 programme remained focused on conducting survey work upon the most repeatedly visited sites, as well as considering new areas of interest as part of the Heritage Lottery funded Ribble Life Together project ( Concurrent electrofishing surveys were conducted by the Environment Agency under their catchment wide monitoring project and responsibilities toward monitoring the impacts abstraction of river water by United Utilities. All duplicate sites were identified prior to the start of the survey season to include EA survey data. Principally, our continuing aims are to: - 1. Assess the overall status of the juvenile population of salmonids. 2. Monitor the inter-annual variations of the salmonid population. 3. Determine underperforming areas. 4. Capture the effectiveness of previous habitat improvement works. 5. Generate data in support of and to report on grant bids and applications. 6. Generate knowledge of rare species to inform responsible development. 7. Locate ecological threats posed by invasive species. 8. Derive future research questions. The Boxing day floods that covered much of the north west in 2015 arrived at a critical point for salmon (Salmo salar) and brown trout (Salmo trutta) spawning. It was the warmest and wettest December on record (dating back to 1919) (Met Office, 2015). The winter floods of 2015/2016 have been described as one of the most extreme and severe hydrological events of the last century ranking alongside the floods of 1947 in severity in a recent report (Marsh et al., 2016). Below average rainfall at the beginning of November precluded exceptional rainfall and flood warnings on the 9th. New November peak flows were registered on the Ribble when compared to 50yr record (Figure 1). Continuing rains the following month reprofiled many of the catchment s rivers and streams culminating in wide-spread damage and destruction to the towns of Whalley, Croston and Ribchester. 3

5 Height / m River Level Details - Samlesbury October October November December January February 2 Date Average Level Maximum Level Flooding possible Typical Range Figure 1 River levels recorded at Samlesbury from October February Raw data was obtained from the Environment Agency and used under the Open Government Licence. Methodology This year, the Ribble catchment s fish population was monitored by the Environment Agency (EA) in fulfilment of its obligations under the Water Framework Directive (2000). Three Environment Agency survey sites overlapped with our monitoring sites compared to 12 the previous year. This difference is mainly due to the rotation of survey effort undertaken by the EA, including biannual and six-yearly survey cycles. Prior to the survey programme the Ribble Rivers Trust (RRT or Trust) co-ordinated with the EA to avoid a duplication of effort at the same locations. The applied methodologies are adapted from the Crozier and Kennedy method (1993) and have been employed by the Trust since All sites were fished upstream in a zigzag pattern over congruous riffle/pool habitats using an E-fish 500W electrofishing backpack system. Typically, two types of survey were undertaken: Semi-quantitative, where the river is fished for five minutes covering a measured un-isolated area without using stopnet; and Quantitative, where a netted area of river is sampled and re-sampled over another two runs. Quantitative surveys allow for the identification of capture efficiencies of each electro fisher, thus allowing more accurate results from semi-quantitative surveys to be presented. Commencing from the 16 th June and closing on the 8 nd October, eight (19 last year) quantitative sites were fished on the Calder, eight (12) on the Hodder, with 12 (thirty-four) completed on the Ribble. The number of quantitative sites fell on the previous year due to an absence of either trout or salmon in three quantitative sites in the Calder catchment. It was suggested that subsequent quantitative sites be assessed prior to surveying using the relative abundance of salmonids caught in neighbouring semiquantitative sites. If there were insufficient densities of salmonids present for a quantitative assessment, the site was surveyed as a semi-quant. This pragmatic approach allowed the team to maintain survey effort across the catchment while ensuring that enough quantitative sites were fished to calibrate the semi-quantitative surveys. A total of two-hundred-eighty-nine (two-hundred-fiftyfour) semi quantitative sites were surveyed, this included eighteen quantitative sites that were fished as semi-quants following the rational above. 4

6 Following on from the review of the 2012 survey season the Trusts 412 survey sites were assigned an index value based on the number consecutive years they had been sampled. Sites assigned the lowest indices hold the greatest priority, with five years continuous data now available for 270 sample sites. The densities of trout and salmon from the above activities were calibrated and allocated a grade score (see Table 1). The grades standardise our field observations with those of the National Fisheries Classification System (NFCS) (National Rivers Authority (now EA), 1994). The system is based upon the number of fry captured per species. These were separable through establishing a maximum fork length for fry (Appendix A), discerned by the two-peaked shape of the frequency-size distribution for all captures. Grades A F are assigned by extrapolating the density of fry per 100m 2 using the number of fry captured over a minimum of five minutes. The capture efficiency of the electrofishing team is calculated by comparing the number of captures in the first run contrasted with the total present. Table 1 NFCS gradings Grade A B C D E F Fish Density Excellent Good Fair Poor Very poor No fish present Once graded the results were transferred to a map layer using ArcGIS to display catchment scale results. Inter-annual comparisons of data featuring in the Results Section are based on REPEATED SURVEY SITES ONLY. This ensures those of a similar habitat type are being compared year on year. Grade results have been averaged and organised within the analysis of this report according to geographical coverage determined by sub-catchment. Use of pre-selected spot surveys provides us with a useful overview of the Ribble s overall population health, particularly where combined with additional tools (e.g. fish counter data). The maps outlined in Figures 2, 9-11, 17, 18 incorporate the following data files, under copyright: Environment Agency copyright and / or database rights All rights reserved; Contains Ordnance Survey data Crown copyright and database right 2017; Additional base-map imagery sources are used in Figures 10, 17, 18: National Geographic, Esri, DeLorme, HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, increment P Corp. All images 2017, Ribble Catchment Conservation Trust. 5

7 Figure 2 Map of the Ribble Catchment outlining the sub-catchment areas discussed in this report Results Natal development was exceptional during 2016 and was most apparent in brown trout fry within the Hodder and Ribble catchments. Shifts in density dependence towards larger average fry length, may counteract poor egg survival (Appendix A). Overall, the best developmental year for salmonid growth occurred during 2012; the wettest recorded summer since RRT commenced sampling. Whilst elevated levels promoted longer adult migrations, the physical stress and energy deficit for developing juveniles are expected to have restricted opportunities for growth (Figures 3). Trends in the maximum trout fry length for the Ribble and Calder were comparable until 2015/2016. Of the three sub-catchments, Hodder trout sizes have been more variable. The Ribble outlines a good year for salmon and trout growth compared to the Calder which received the most rainfall of the three sub-catchments over winter 2015/16. 6

8 Maximum Length of Trout fry <1 year old Maximum Length of Salmon fry <1 year old Length / mm Year Ribble Calder Hodder Series4 Figure 3 Graph comparing trout and salmon fry cut-off lengths from the previous nine years of RRT surveys Low salmon fry abundances in 2016 provided a paucity of data for aging purposes. For example, this year salmon fry captured at two nearby locations; on the main stem Ribble and local tributary, 400m away on the same day, discovered average fry lengths of 93.8mm (n5) and; 75.6mm (n25) respectively. The between site variability and generally low occurrence of salmon fry suggest that survivorship and successful development have been more parochial. For both salmon and trout, average fry lengths for the Ribble equated to larger sizes with increasing sizes encountered as each subcatchment was sampled in sequence: Calder, Lower Ribble, Hodder, Middle Ribble, Upper Ribble. With additional resource the collection of scales or DNA samples from the salmon and trout fry off each sub-catchment could be used to validate ageing and the accuracy of reported cut-off lengths. 7

9 Number of Sites Number of Sites A B C D E F Trout Figure 4 NFCS Trout grades compared over the last three years. Trout fry are present at A - E grades, an F grade denotes an absence of fry The large increase in F grade sites in 2016 across the whole of the Ribble catchment disproportionably attributable to the Calder system. The likewise fall in E grade, would suggest that marginal sites for trout fry in 2015 did not produce viable returns of fry in 2016 (Figure 4) A B C D E F Salmon Figure 5 NFCS salmon grades compared over the last three years. Salmon fry are present at A - E grades, an F grade denoted an absence of fry The comparative salmon grades of the past three years show an increase in A, B, C, and F grades with a decrease in D and E grades. Continually, a high number of F grades show that salmon spawning success is limited to a select number of sites (Figure 5). 8

10 Total Grade Score Average Grade 9 year trend for Trout Year Figure 6 Graph showing the total (blue line) and average (red square) grade scores for trout fry over the past 9 years. Grade 1 corresponds to grade F scaling up to 6 for grade A. The inclusion of main stem Ribble sites added in 2015 were retained for 2016 translating to six sites on the programme. In 2015 the high densities of salmon fry encountered on the main stem were consistent with the redd spawning locations obtained from the spring salmon tracking study (see salmon fry were found again at all of these sites in 2016, with the average grade decreases by a factor of one. Sabden brook, Swanside, Ings becks sustained good trout fry recruitment during 2016 (Figure 8) where salmon fry have been absent over the past two years. (Figure 10). The presence of other non-salmonid species, and salmon parr suggests that very low numbers persist and their decline is not owing to any determinable reduction in habitat or water quality. Importantly, all three brooks were previously excellent spawning tributaries for salmon. Given that the return period for multi-sea winter salmon will be nominally up to four years, our observed fry abundances do not follow any cyclical patterns or peaks (RRT, 2015). Such observations suggest that there is reduced spawning success. The status of salmon in the Ribble has recently been classed as at risk, and of the 42 primary salmon rivers in England, none are listed as not at risk (Chare, 2016). This must provide a trigger for greater urgency in intervening on the Ribble via the five-point approach to Atlantic salmon survival providing a focal point for future works (Chare, 2016). 9

11 Species Summaries Brown Trout Calder The start of the electrofishing season on the upper Calder catchment produced broadly disappointing results for brown trout. The impact of the extreme water levels were most pronounced upon the Calder catchment compared to the Hodder and Ribble (Figure 9). The River Don/Thursden Brook bore significant physical changes with a total absence of fry across all sites. Observations of the large shifts in gravel substrate and changes to riparian habitat were apparent and indicative of the level of habitat disturbance juvenile fish would encounter. Similarly, low trout fry abundances were observed across the Rivers Brun and the lower reaches/main stem of the Calder. This is disheartening where trout populations of the Rivers Calder and Don, and the top of the River Brun were observed to be in a healthy state during the previous year. Trout fry survivorship was higher within the physically smaller tributaries of the Calder more so than main stem sites, which acted as refuges. Figure 7 Extensive fresh gravel movements on the River Don. Hodder Trout fry returns were below the 9-year average for the River Dunsop, well as for the tributaries of the Hodder above Stocks Reservoir; grades have fallen across all sites for a second consecutive year. Small feeder streams within the catchment have provided good returns of trout. Easington beck yielded poor returns for trout fry throughout its course, although greater numbers of coarse species are prevailing, especially along its lower half. Riparian growth within four old Trust habitat schemes along the brook are improving year on year, reducing the potential for bank erosion, providing tree cover, in stream habitat and contributing carbon (Figure 8). 10

12 Figure 8 Riparian growth within an old Trust habitat scheme along Easington Brook Ribble (downstream of Gisburn to Brockholes) The tributaries of the lower Ribble were largely absent of any salmonids and consistent with the findings of the previous eight years. Downham brook that runs through Chatburn provided an exceptional result; four trout fry. The population of trout in this beck was wiped out during the mid s and this is the first evidence of stocked fry from a neighbouring stream prevailing. This brook is cut-off from any upstream migration via a series of natural and artificial barriers so no natural repopulation could occur. Good returns of Brown trout were also found in the tributaries north of West Bradford up towards Gisburn. Ribble (upstream of Gisburn) Results from the upper catchment have remained largely unchanged over the previous year and provided the greatest consistency compared with other sub-catchments further to the winter floods. Even though there has been a generally poor return and recruitment for trout fry, trout are still present across the catchment and it is hoped that rearing streams successful in 2016 will continue to reseed streams that underperformed (Figure 9, 10). 11

13 Scale: 1: 220, km Figure 9 Catchment map showing brown trout fry NFCS grades from surveys undertaken by RRT and the EA in Green points indicate higher grades and therefore higher trout densities, decreasing to orange. Red indicates an absence of trout fry. 12

14 Paul Peters Figure 10 Catchment map comparing the presence of trout found across the past two years of surveys. This data contains fry, parr, and adult records. 13

15 Salmon Calder Salmon recruitment fell across the catchment, with greatest decline observed across the Calder catchment (Figure 11). No salmon fry were captured at all this year and only a small number of the salmon parr (5) were found at the foot of Sabden brook. Previously, Sabden water has provided routinely good returns of salmon fry year on year. Hodder Monitoring sites along the Hodder s tributaries have also shown a poor return for salmon particularly those for the Rivers Dunsop and Langden. Last year there were concerns over poor (relative to the brook) returns of fry found in Croasdale Brook. Thankfully the worry has been short-lived as this year results were more in keeping with our long-term record of excellent and good returns for this water. Easington beck did yield an improvement over the previous year, with notably large fry, possibly benefiting from reduced trout competition. Considering the unfavourable weather conditions, this year has performed better than last year, however the long-term deteriorating trend for salmon in the Hodder catchment and wider Ribble is of concern. Ribble (downstream of Gisburn to Brockholes) The tributaries of the lower Ribble remain absent of any salmonids and consistent with the findings of the previous eight years. Ribble (upstream of Gisburn) Main stem sites returned low densities of fry; along with streams displaying high levels of gravel movements. The stretch of main stem Ribble from Sawley up to Nappa retained salmon although in lower numbers than in Results from the upper catchment remained largely unchanged over the previous year and provided better consistency than elsewhere on the catchment further to the 2016 winter floods. Salmon fry returned to Wigglesworth beck after an absence of six years. Growth of salmonid fry surpassed that of previous years; providing more hope for improved survivorship during the winter and healthy parr during our next annual survey programme (Figure 3, Appendix A). 14

16 Scale: 1: 220, km Figure 11 Catchment map showing salmon fry NFCS grades from surveys undertaken by RRT and EA in Green points indicate higher grades and therefore higher salmon densities, decreasing to orange. Red indicates an absence of salmon fry 15

17 Sabden brook, outlined as one of most important tributaries for salmon spawning on the Calder (RRT, 2015) has not yielded salmon fry for two years. Under plans for the Ribble Life Together project the weir within Sabden village would be made passable to migratory fish, unlocking 5km of additional water course upstream. Work will commence in May/June of Figure 12 Sabden Weir (2016). The current fish passage design includes a rock-ramp and groynes 16

18 Average per site Coarse Species The species captured as bycatch across the Ribble display values similar to last summer (Figure 13). The increase in the number of coarse species not routinely captured, specifically grayling (Thymallus thymallus), should be noted. Large numbers of chub (Squalius cephalus), gudgeon (Gobio gobio) and grayling were scattered in and around Long Preston deeps surrounding tributaries; Wigglesworth beck, Rathmell, Long Preston, Hellifield, highlight the deeps as an important rearing site for coarse fish. Average Species Bycatch in the Ribble Catchment Species Figure 13 The chart above displays the average number of each species captured as bycatch. The highlighted values show the total number caught in Bullhead (Cottus gobio), stone loach (Barbatula barbatula) and minnow (Phoxinus phoxinus) catches remained the same as last summer suggesting that the extreme flows in 2015/16 were less of a concern for these species. 17

19 Grayling Figure 14 A grayling fry caught on Holden Brook near Sawley. Grayling fry and parr and other coarse species have prospered during an otherwise poor developmental year for salmon and trout. More Grayling were captured during 2016 than the previous eight years of sampling, however numbers are still low compared to other bycatch (Figure 13). There is limited knowledge of habitat use and requirements (Sempeski et al., 1998) across the catchment, conspicuously the positive result arrives at a time of poor recruitment for salmon and trout. Grayling are an indicator species of good water quality and connectivity due to their reduced swimming ability (where compared to salmon) (EA, 2015), showcasing the excellent habitat that is available to wildlife within the Ribble. The increase in grayling fry is consistent with catches across the Trust angling passport beats ( making up 29% of the total catch this year (Appendix B). Most captures have been along the Mitton beat on the Ribble and Calderfoot (99 from of a total 120). An adult grayling was also captured along Colne Water, a significant and welcome development. It is unknown where this grayling has migrated from however, up until the partial removal of Padiham weir in 2010 and subsequent fish easements along Colne water in 2014 it would have been impossible for grayling to have migrated upstream. 18

20 Number of Eels Eel The number of eels captured during our surveys dropped again this year. Over 90% of captured elver and bootstrap eels (<150mm) were found in the lower Ribble area, highlighting this as a significant area for juvenile development. 30 Size of eels found Length (mm) Figure 15 Approximate size of eel compared across the past three years Figure 15 compares estimated lengths of captured eels over the past three years of survey work. Prior to 2014 only the presence and number of eels was recorded, with sporadic length measurements for the occasional specimen. With further development of this aspect of our monitoring programme we aim to understand the age structure of the Ribble s population and advise on where key areas for eels of different life stages reside. Utilising eel number and presence data from the past 9 years of survey work, priority areas for future eel specific investigations have been identified; it is hoped that future projects might track eel movements and habitat use within the Ribble Catchment. It is apparent that eel are found throughout the Ribble, except the upper headwaters. As our monitoring of the Ribble specifically targets salmonids, the true extent and or abundance of eel is likely under-reported. According to Knights et al., (2001), semi-quantitative sampling methods without the use of an upstream stop net severely underestimates the number of eels present. The distribution of our survey sites is also limited to streams and rivers populated with salmonids and does not include other lotic systems which may harbour populations of eel. Knights et al., (2001) suggests use of eel specific electrofishing methodologies, however, subsequent analysis of eel specific and multi-species surveys (coarse, salmonid) concluded that eel populations were not underestimated by a multi-species approach to monitoring (Baldwin and Aprahmian, 2012). In the event of targeted research into the life history of Ribble eels, it is likely that an eel specific survey method would be used. 19

21 Distinctive clusters of yellow-bellied adults around Dunsop Bridge and further along the River Hodder and Calder (Figure 17,18) are notable from our survey sites and their discovery above man-made structures, otherwise impassable to migratory salmonids is surprising (Figure 16). Figure 16 Weir at the top of Pendle Water, Near Roughlee. Two eel were caught upstream of here. 20

22 Figure 17 Catchment map outlining the presence of eels during survey work carried out in the Ribble over the past 9 years of RRT monitoring. 21

23 Figure 18 Map outlines eel presence during 2016 RRT surveys. Counts are provided as number of eels seen/captured in a 5-minute electrofishing survey. Red circles denote areas of continued eel presence throughout the long-term data set. 22

24 Crayfish Fewer white-clawed crayfish (Austropotamobius pallipes) were encountered in 2016 compared to last year. Last summer s sighting of an invasive American Signal Crayfish (Pacifastacus leniusculus) in Trawden Brook, Cliviger at the top of the Calder system was a worrying development. At the time a local commented that signals were placed into Trawden four years ago for eating purposes and these are being collected (RRT, 2015). During the summer surveys on Trawden Brook ASC were encountered 500m downstream of the original discovery site in Whilst crayfish are a bycatch in our surveys it is the first time that we have encountered their presence in this location suggesting that their range throughout Colne Water is increasing. Paul Peters Figure 19 Left. adult male American Signal Crayfish capture in Long Preston beck, and, right, ASC carcass from Trawden beck. This summer two individuals were captured near the bottom of Long Preston beck, 1.8km from their sighting during the 2015 surveys. Bubb, Thom, Lucas, (2004) have shown that ASC have an active range of 280m (upstream) to 400m (downstream) within an upland river system). The working hypothesis from the study is that the presence of ASC further down Long Preston beck would be linked to passive transport by high river discharge and moreover, like those witnessed in In the absence of a comprehensive survey of the beck to assess the location and spread, the theory remains untested. ASC s adaptability and our historic introduction of individuals poses an immediate management challenge to the aquatic species of Long Preston SSSI (Diéguez-Uribeondo J., 2006). Of the numerous methods for controlling ASC, few have been successful. The distribution of ASC is occurring faster than our surveys can realistically measure, or address through remedial actions (which RRT does not currently employ). Confirmed sightings of ASC stretch across the width of the catchment and the threat requires more urgent effort to halt to the spread of ASC and associated White-clawed crayfish plague through, Check, Clean, Dry protocols ( 23

25 Conclusions The impact of the 2015 winter floods has been wide reaching, particularly salmonids on the Calder catchment. The greatest resilience has been demonstrated by the trout population of the upper catchment with the overall trend for the Ribble catchment being one of gradual decline since Concerns remain over the low salmon fry recruitment, specifically within the Hodder tributaries of the Rivers Langden and Dunsop. Poor returns are indicative of the poor marine survival rates recorded by anglers and netsmen during the fishing season (February October). Although smaller tributaries fared better than the main river, grayling and other coarse species prospered, leading us to question whether this is in response to the displacement of salmonids, their adaptability or other factors that remain undetermined. Recommendations The recommendations from this year s findings are as follows: - Direct Project Officers towards targeted habitat improvement works observed at survey locations in addition to revisits to existing schemes that require maintenance. Continue inter-annual electrofishing monitoring of CRF area sites for cost/benefit monitoring purposes. As a minimum, such an exercise ought to sustain and extend the 9-year record of RRT fisheries data held across 89 sites. Continue to monitor the main stem Ribble, with the possibility of increasing the number of main stem sites. Evaluate the efficiency of single anode backpack electric fishing along main rivers. Monitor the movement of smolts/kelts, and eels (within the outlined hot-spots) and use the barrier prioritisation model to assess the downstream passage efficiency of existing barriers or fish passes. Support targeted research into the growing population of American Signal Crayfish particularly where they interface with the extending range of juvenile salmon (upper Calder catchment). Urgent, high resolution studies of increasing distribution of invasive ASC in Trawden brook and Long Preston Beck. Continue to monitor sites above fish easements/passes to assess their success in allowing multiple fish-species migration and specifically targeting Calder sites. Consider future research into the proposed topics: - 1. Systematic monitoring of water courses connecting stocked fisheries to ascertain potential changes in community structure and proximity to salmonid rearing areas. Barrow Brook, Dean Clough (Calder) and the upper main stem of the Hodder would provide suitable tributaries for study. 24

26 2. Examination of Bullhead and Stone Loach interactions with salmonid communities: Calculate Salmonid fry:parr ratios with a high resolution spatial data set. Could the initiation of disturbance events boost salmonid spawning and rearing success (or would primary colonisation by non-salmonids occur)? 3. Re-classify low NFCS grade Ribble tributaries according to their coarse species populations over and above salmonids. 4. Examine grayling behaviour in the Ribble, with greater focus placed upon their resource utilisation and interspecific competition with other salmonids in lower order streams. 5. Explore Long Preston deeps as a significant rearing ground for coarse species and possible predation bottleneck. 6. Explore growth patterns of YoY trout across Ribble, Calder, Hodder by collecting scale samples. 7. Establish and quantify the movement of elvers through hydrometry stations retrofitted with pumped elver passes. 25

27 References Armstrong, J. and Nislow, K. (2006). Critical habitat during the transition from maternal provisioning in freshwater fish, with emphasis on Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). J Zoology, 269(4), pp Baldwin, L. & Aprahamian, M. (2012). An evaluation of electric fishing for assessment of resident eel in rivers. Fisheries Research, , Bernardo, J., Costa, A., Bruxelas, S., & Teixeira, A. (2011). Dispersal and coexistence of two nonnative crayfish species (Pacifastacus leniusculus and Procambarus clarkii) in NE Portugal over a 10-year period. Knowledge And Management Of Aquatic Ecosystems, (401), Bubb, D., Thom, T., & Lucas, M. (2004). Movement and dispersal of the invasive signal crayfish Pacifastacus leniusculus in upland rivers. Freshwater Biology, 49(3), Cattanà o, F., Lamouroux, N., Breil, P. and Capra, H. (2002). The influence of hydrological and biotic processes on brown trout (Salmo trutta ) population dynamics. Can. J. Fish. Aquat. Sci., 59(1), pp Chapman, D. (1988). Critical Review of Variables Used to Define Effects of Fines in Redds of Large Salmonids. Transactions of the American Fisheries Society, 117(1), pp Chare, S. (2016). Restoring Salmon in England. Salmon Five Point Approach. In IFM Annual Conference. Norwich. Crozier, W.W., and Kennedy, G.J.A. (1993). Application of semi-quantitative electrofishing to juvenile salmonids stock surveys. Journal of Fish Biology, 45, Diéguez-Uribeondo, J. (2006). The Dispersion Of The Aphanomyces Astaci-Carrier Pacifastacus Leniusculus By Humans Represents The Main Cause Of Disappearance Of The Indigenous Crayfish Austropotamobius Pallipes In Navarra. Bulletin Français De La Pêche Et De La Pisciculture, ( ), Environment Agency. (2005). Seasonal Movements and Habitat use of Grayling in the UK. Bristol: Enviroment Agency. Finstad, A., Saettem, L., Einum, S. and Fleming, I. (2013). Historical abundance and spatial distributions of spawners determine juvenile habitat accessibility in salmon: implications for population dynamics and management targets. Can. J. Fish. Aquat. Sci., 70(9), pp Knights, B., Bark, A., Ball, M., Williams, F., Winter, E., Dunn, S., Eel and Elver Stocks in England 26

28 and Wales Status and Management Options. Environment Agency Technical Report W248, Bristol Louhi, P., Ovaska, M., MÃ ki-petã ys, A., Erkinaro, J., Muotka, T. and Rosenfeld, J. (2011). Does fine sediment constrain salmonid alevin development and survival? Can. J. Fish. Aquat. Sci., 68(10), pp Macdonald, J., King, C. and Herunter, H. (2010). Sediment and Salmon: The Role of Spawning Sockeye Salmon in Annual Bed Load Transport Characteristics in Small, Interior Streams of British Columbia. Transactions of the American Fisheries Society, 139(3), pp Maki-Petäys, A., Muotka, T., Huusko, A., Tikkanen, P. and Kreivi, P. (1997). Seasonal changes in habitat use and preference by juvenile brown trout, Salmo trutta, in a northern boreal river. Canadian Journal of Fisheries and Aquatic Sciences, 54(3), pp Marsh, T.J.1, Kirby, C.2, Muchan, K.1, Barker, L.1, Henderson, E.2 and Hannaford, J.1 (2016). The winter floods of 2015/2016 in the UK - a review. Centre for Ecology & Hydrology, Wallingford, UK. 37 pages. Met Office, (2015) Weather Summaries. [online] Available at: [Accessed 3 Nov. 2015]. National River Authority (1994) - National Fisheries Classification Scheme. A guide for users. R& D report No Persson, L. (1983). Food Consumption and Competition between Age Classes in a Perch Perca fluviatilis Population in a Shallow Eutrophic Lake. Oikos, 40(2), p.197. Peters, P., (2015) Ribble Rivers Trust: Fisheries Monitoring of the Ribble Catchment. Unpublished. Roy, M., Roy, A., Grant, J. and Bergeron, N. (2013). Individual variability of wild juvenile Atlantic salmon activity patterns: effect of flow stage, temperature, and habitat use. Can. J. Fish. Aquat. Sci., 70(7), pp Sempeski, P., Gaudin, P. and Herouin, E., Experimental study of young grayling (Thymallus thymallus) physical habitat selection factors in an artificial stream. Archiv für Hydrobiologie, 141(3), pp

29 Appendices Appendix A Table 2 Fry and parr cut off lengths (mm). Lengths from 2015 are bracketed. Sub-catchment Trout Salmon Hodder 93 (86) 88 (80) Calder 92 (86) n/a (80) Ribble 125 (105) 105 (105) *The mortality rate of captured salmonids during 2016 was less than 1% of the total number of captures. Additional graphs outlining young of year (YoY) cut-off lengths for trout and salmon are provided below. 28

30 Number of fish Ribble Trout Fry Hodder Trout Fry Calder Trout Fry Length / mm 29

31 Number of fish Ribble Salmon Fry Hodder Salmon Fry Calder Salmon Fry Length / mm 30

32 Number of fish Salmonid Captures Year T_fry S_fry T_parr S_parr Poly. (T_fry) Poly. (S_fry) Poly. (T_parr) Poly. (S_parr) Comparison of salmonid captures from This does not contain missed fish data as species could not be attributed. 31

33 Number of fish captureed Appendix B Angling Passport Summary for the fishing season. Data provided is received as catch return slips from anglers. A comprehensive list of angling passport beats can be viewed here: Fish captured on the Mitton Beat Brown Trout Sea Trout Chub Grayling Salmon Roach Dace Nov-15 Dec-15 Jan-16 Feb-16 Mar-16 Apr-16 May-16 Jun-16 Jul-16 Aug-16 Sep-16 Oct-16 Month Figure 1. Total fish captures of all species for the season on Mitton beat. Table 1. Fish captures on Mitton fishing beat for the period November 2015 October 2016 Species Total Caught Over the Season Mitton Caught Over the Season Total % Out of Season Captures Peak Fishing Month* Caught in Month Out of Season? Salmon October 8 No Brown Trout May 43 No Sea Trout August 9 No Grayling October 35 No Chub June 5 No Roach August 9 No Dace September 7 No 32

34 Total Captures / log^10 Total fish captures accross nine beats 2% 6% 8% 4% 29% 45% 6% Salmon Brown Trout Sea Trout Grayling Chub Roach Dace Figure 2. Pie chart showing the total number of fish for each species caught across all beats Inter-anual catch return comparison of Mitton Beat 2012/ / / / / / Salmon (Adult) Salmon (Parr) Brown Trout Sea Trout Grayling Chub Dace Eels Species Figure 3. Inter-annual comparison of each species across four seasons on the Mitton beat. Table 2. The number of tokens sold and the number of catch returns received November 2015 October 2016 Angling passport (books) Number of tokens Mitton Number of tokens Office Total number of tokens sold Number of catch returns * Trout and coarse Salmon *345 tokens or 69 books worth 33