656 16 Fish Population Survey Report
Total Page:16
File Type:pdf, Size:1020Kb
Fish population summary report River Welland, 2017 This report provides a brief summary of results from recent fish population surveys on the River Welland between Market Harborough and Spalding. The surveys were carried out to assess the health of the river and enable successful management of our principal fisheries. Seaton weir rock ramp fish pass (part of several habitat improvements on the upper river). Originating team Lincolnshire & Northamptonshire Analysis & Reporting Team Author(s) Jake Reeds Date January 2018 Summary • Ten electric fishing sites were surveyed during 2017 along the upper Welland (above Peakirk). The wide river downstream of this between Crowland Bridge and Spalding was surveyed using hydroacoustic technology during the night when fish are more active. • Sixteen species of fish were recorded and a total of 1110 fish were captured for measurement in the upper river electric fishing sites. • Chub and dace were the most widespread species, being recorded at seven and six sites respectively. • Roach were the most numerous species. Site locations: © Environment Agency copyright 2018. All rights reserved. Ordnance Survey licence number 100024198. Sites varied between 100 - 200m in length, each site was isolated using stop nets at the upstream and downstream limit. It was then electric fished twice with fish being placed in a recovery tank immediately after capture. All fish are then identified for species, measured to fork length and returned to the river. Survey results - summary Fish density for fish greater than 99mm in length (fish/100mˉ²) from the electric fishing sites undertaken is shown below. Fish lengths for all sizes are given to indicate the overall size range found at the site. US Great US Ashley DS DS US Lubenham US Wakerly Stamford Tallngton Bowden Road Weir Harringworth Duddington Hudds Mill Sandy Lane Road Bridge Road Bridge Meadows (Maxey Cut) Bridge Road Bridge Road Bridge Brown Trout Density - - - 0.571 - 0.222 - - 1.375 - Size range - - - 118 – 381mm - 125 - 572mm - - 343 - 454mm - Chub Density 1.5 3.42 - 1.143 0.66 1 1.042 0.75 1 - Size range 132 - 158mm 142 - 228mm - 144 - 237mm 187 - 372mm 187 - 518mm 135 - 494mm 107 - 425mm 248 - 414mm - Common Bream Density - - - - - - - - - - Size range - - - - - - - - - - Dace Density - 1.71 - 0.143 0.333 0.556 0.938 0.167 0.125 31.6 Size range - 90 – 202mm - 84 -132mm 187 -372mm 84 - 170mm 77 - 207mm 62 - 124mm 110mm 48 - 224mm Eel Density - - - - - - 0.208 0.083 0.5 1.2 Size range - - - - - - 430 - 610mm 445mm 255 - 420mm 108 - 492mm Gudgeon Density - 0.14 - - 0.25 - - - - 0.4 Size range - 105mm - - 87 - 134mm - - - - 82 - 100mm Perch Density - - - - - 3.556 0.521 0.083 - 0.267 Size range - - - - - 68 - 218mm 147 - 214mm 330 - 332mm - 45 - 241mm Pike Density - - - - 0.167 0.667 0.938 0.75 0.625 2.933 Size range - - - - 507 – 818mm 474 - 684mm 156 - 529mm 258 - 604mm 238 - 571 131 - 434mm Roach Density - - - - - 0.333 3.125 5.333 0.125 19.2 Size range - - - - - 120 - 138mm 87 - 231mm 44 - 172mm 137mm 45 - 264mm RBH Density - - - - - - - - - 0.133 Size range - - - - - - - - - 139mm Tench Density - - - - - - - - - 0.133 Size range - - - - - - - - - 150mm Minor species 3SS, BH, MN, 3SS, MN, 3SS, BH, MN, BH, MN, STL 3SS, BH, MN, 3SS, BH, MN, BH, MN BH, MN, STL BH, MN - present STL STL STL STL, BL STL, SPL Key: 3SS = Three Spined Stickleback, BH = Bullhead, STL = Stone Loach, SPL = Spined Loach, MN = Minnow, BL = Brook Lamprey Upper River fish density per site (fish>99mm): 60 Brown trout Chub Common bream Dace Eels Gudgeon Perch Pike Roach Roach bream hybrid Ruffe Tench 50 40 ˉ²) 30 20 Fish Fish density (fish/100m 10 0 U/S U/S Great U/S Ashley D/S U/S Wakerly D/S Stamford Hudds Mill Tallington Sandy Lane Lubenham RB Bowden RB Weir Harringworth RB Duddington Meadows D/S Weir RB RB Small fish are difficult to catch efficiently using standard electric fishing techniques, it is highly likely that fish under 100mm in length are underrepresented in survey results. The potential voltage difference during electric fishing over small fish can be minor, meaning they are not necessarily captured when fishing. Due to the mesh size used in fish capture they can sometimes evade being picked up in a survey. Density estimates are configured using fish above 99mm in length, this gives more accurate results when looking over long term trends. The catch at Sandy Lane in Market Deeping dominates the survey results with over 750 fish caught in the survey section. The majority of the fish caught here were dace and roach with the largest fish being 224mm and 264mm respectively. That would be an adult dace around seven years old and a roach approaching a pound in weight and would be around ten years old. The sites at Duddington, Stamford Meadows and Hudds Mill all produced similar density results with catches being made up mostly of perch and roach. Trout were present at two sites above Stamford, at Harringworth and Duddington which produced the largest trout at over 50cm (likely to be a stocked fish). Tallington on the Maxey Cut held the highest numbers of trout present in a survey in the river with eleven fish caught in the survey stretch. The habitat in the Maxey Cut has improved for salmonids with associated works carried out by the Environment Agency’s Fisheries, Biodiversity and Geomorphology team. Upper River length frequency results: Brown Trout 3 2 1 Number of fish of Number 0 145 250 355 115 130 160 175 190 205 220 235 265 280 295 310 325 340 370 385 400 415 430 445 460 475 490 505 520 535 550 565 Fish Length (mm) Low numbers of brown trout were caught during surveying throughout sites in the upper river, the largest was in the 570mm size range, this is likely to be a previously stocked fish (photo below). Hydrology and habitat will be a key factor in enabling a healthy trout population in the river, the improvements made to the river led by Fisheries Technical Officer Hugh Bunker will go some way to address this and is illustrated later in the report. It is likely the population illustrated in this report is underrepresented due to the relatively small survey distance covered when compared to the length of the river. The largest trout taken from the Welland at Duddington (likely to be a stocked fish). Trout taken downstream of Tallington Weir. Chub 8 7 6 5 4 3 Number of fish of Number 2 1 0 105 120 135 150 165 180 195 210 225 240 255 270 285 300 315 330 345 360 375 390 405 420 435 450 465 480 495 510 Fish Length (mm) The largest chub caught at Duddington was in the 515mm size bracket which would represent a fish of around 5lbs. The smallest fish caught was 105 mm which would have been spawned in 2016. Numbers of fish in the juvenile age range show that recruitment is taking place in the river, in general numbers of chub were low, large chub are quite an easy target for predators in the system so this could be impacting numbers. Dace 80 70 60 50 40 30 Number of fish of Number 20 10 0 45 50 55 60 65 70 75 80 85 90 95 100105110115120125130135140145150155160165170175180185190195200205210215220 Fish Length (mm) Few juvenile dace below 80mm were caught during surveying but this is often the case, they tend to favour habitat where they can’t be caught easily and are underrepresented in most fisheries data sets. Most fish reside between 90mm and 115mm long and they are present in good numbers. The largest fish caught measured 220mm and would represent a fish of around 7 years old. Eel 3 2 1 Number of fish of Number 0 190 205 220 235 250 265 280 295 310 325 340 355 370 385 400 415 430 445 460 475 490 505 520 535 550 565 580 595 610 Fish Length (mm) The largest eel in the 610mm length distribution would be a female that would be starting to get to the size where they are ready to begin their seaward migration to spawn. Numbers of eel are low against historical catches on the Welland, this reduction is shown in many data sets around the country as the species continues to struggle. Roach 100 90 80 70 60 50 40 Number of fish of Number 30 20 10 0 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 Fish Length (mm) All the roach captured in the surveys were from sites downstream of Duddington Road Bridge. There are roach present in Market Harborough Town Centre but numbers from the upper river are low these days, the upper river used to hold some specimen fish but these are no longer caught during surveys. The largest fish caught was at Sandy Lane in Market Deeping at 264mm long, this would be a fish around ten years old. The site there held the highest density of roach in the river also, anywhere downstream of low locks in likely to contain sizeable fish. Stamford Meadows usually produces some good roach, the largest fish there was 231mm. Historical data: Data from three sites where we hold long term electric fishing records is shown below. Results are given in fish density/100mˉ² for fish greater than 99mm in length, fish smaller than this are unrepresented in the data due to their size making results from them inaccurate. Fish density (fish/100mˉ²) D/S Harringworth Road Bridge 18 With stocked trout 16 Without stocked trout 14 12 10 8 6 4 2 0 1990 1993 2000 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2017 Historical catch data from D/S Harringworth Road Bridge.