Fish population survey report

Transcription

1 Fish population survey report River Lugg This report provides a summary of results from recent fish population surveys on the River Lugg between Leominster and Hereford. The surveys were carried out to assess the health of the river and enable successful management of our principal coarse fisheries. Downstream Lugwardine Bridge, River Lugg, fish survey site. Originating team Author(s) Date Checked by Sign-off date West Midlands (SHWG) Analysis and Reporting Team Libby Capps 14-Feb-2017 Martin Fenn 20-March-2017

2 Summary 2 sites on the River Lugg were surveyed by electric fishing in August 2011 and September sites on the River Lugg were surveyed by fry netting in September between 2013 and 2015; 12 species of fish were recorded and a total of 8456 fish were captured; Minnow and stone loach were the most widespread species, being recorded at 6 sites. Minnow were the most numerous species and chub were the most numerous species of angling interest. River levels were too high in 2016 to be able to carry out fry surveys.

3 Site locations Figure 1: Map showing the location of the River Lugg coarse fish survey locations.

4 Survey results Surveying was unable to take place in 2012 and 2016 due to high river levels. In 2015 higher flows were also observed in comparison to 2014, making surveying difficult and preventing the weights on the fry net from sitting satisfactorily on the river bed. Table 1: The coarse fish sites surveyed and by which method on the River Lugg. Site Name Survey Method Bodenham Bridge Bodenham Church Fry survey Fry survey Marden Electric fishing - boat Marden Fry survey 300m Downstream Lugg Bridge Downstream Lugg Bridge Downstream Lugg Bridge Fry survey Electric fishing - boat Fry survey Mordiford Fry survey

5 Table 2: Numbers caught and size range (min max, mm) recorded during fry surveys in Bodenham Mordiford Barbel Number - 4 Size range Chub Number - 8 Size range spined stickleback Number - - Size range - - Minnow Number Size range Stoneloach Number 2 16 Size range Grayling Number - 1 Size range - 75 Dace Number - 12 Atlantic Salmon Size range Number - 2 Size range Bleak Number - 1 Size range - 32 Roach Number - 1 Size range - 33

6 Table 3: Numbers caught and size range (min max, mm) recorded during fry surveys in Downstream Mordiford Bodenham Marden Lugg Bridge Barbel Number Size range Chub Number Size range spined stickleback Number Size range Minnow Number Size range Stoneloach Number Size range Dace Number Atlantic Salmon Size range Number Size range

7 Table 4: Numbers caught and size range (min max, mm) recorded during fry surveys in m Bodenham Marden Downstream Mordiford Church Lugg Bridge Barbel Number Size range Chub Number Size range spined stickleback Number Size range Minnow Number Size range Stoneloach Number Size range Grayling Number Size range Dace Number Size range Gudgeon Number Size range Bullhead Number Size range

8 Table 5: Density (number of fish per 100m 2 ) and size range (min max, mm) recorded during the 2011 electric fishing surveys. Atlantic Salmon Marden Downstream Lugg Bridge Density Size range Grayling Density Brown Trout Size range Density Size range Chub Density Size range Dace Density Size range Bleak Density Size range Gudgeon Density Size range Roach Density Size range Perch Density Abundance Minnow Category Stoneloach Abundance Category Size range

9 Table 6: Density (number of fish per 100m 2 ) and size range (min max, mm) recorded during the 2013 electric fishing surveys for key species. Atlantic Salmon Marden Downstream Lugg Bridge Density Size range Grayling Density Brown Trout Size range Density Size range Dace Density Size range Bullhead Density Size range Minnow Density Size range Stoneloach Density Size range 50 -

10 Figure 2: Key fish species caught at Bodenham Church fry survey site in Figure 3: Key fish species caught in Marden fry surveys.

11 Figure 4: Key fish species caught at Downstream Lugg Bridge fry survey site. Figure 5: Key fish species caught at 300m Downstream Lugg Bridge fry survey site.

12 Figure 6: Key fish species caught at Marden electric fishing survey site in 2011 and Figure 7: Key fish species caught at Downstream Lugg Bridge electric fishing survey site in 2011 and 2013.

13 Figure 8: Key fish species caught at Mordiford fry surveys.

14 WFD Classification The fish sites are located in WFD waterbody River Lugg confluence with the River Arrow to confluence with the River Wye, GB The waterbody is not classified for fish as its characteristics make it unsuitable to survey using the WFD methodology. The waterbody is classified as Moderate status in 2015 due to the classification of macrophytes. Table 7, below, shows an overview of the WFD classifications for the waterbody. Table 7: River Lugg, GB , 2015 WFD classification. Element WFD Classification Overall Waterbody Status Moderate Invertebrates High Macrophytes Moderate Phys-chem Good Ammonia High Biological Oxygen Demand High Dissolved Oxygen High ph High Phosphate Good Temperature High

15 Health of fish population Out of the 2 fry surveys carried out in 2013 minnow were the most numerous species, while dace were the most numerous species of angler interest. The largest fish was an Atlantic salmon measuring 134mm recorded at Mordiford. In 2014 minnow were again the most numerous species recorded in the fry surveys and chub was the most numerous species of angler interest. An Atlantic salmon was once again the largest fish, measuring 124mm caught at Mordiford. In 2015, from all 4 fry surveys undertaken minnow were the most numerous species and chub were the most numerous species of angler interest. The largest fish was a gudgeon, measuring 114m caught at Marden. From the electric fishing surveys carried out in 2011 and 2013 minnow were the most abundant species. In 2011 grayling were recorded at the highest density and the largest fish was a chub, measuring 500mm recorded at Downstream Lugg Bridge. In 2013 dace were recorded at the highest density and the largest fish was a brown trout, measuring 380mm and recorded at Marden The diversity of coarse fish species is variable between sites and survey years, particularly in the fry survey results. The variability is likely to be due to the suitability of the sites and the influence of flow on the survey methodology. To undertake fry surveys on the River Lugg, river levels need to be low and conditions perfect. At all of the sites the edge of the survey area becomes very deep and drops off quickly, if river levels are slightly elevated the net does not sit satisfactorily on the bottom of the river bed making survey results unreliable and inaccurate. Although the abundance of coarse fish species is not consistently high, in each survey year across the sites there is a variety of species present in a low abundance. Chub were the most common coarse fish species and was present in 70% of surveys. There is a good number of minor species at each survey site, with minnow and stoneloach being recorded at the majority of sites. Although the survey methods were not targeted towards salmonid species, Atlantic salmon, grayling and brown trout were recorded in the fry and electric fishing surveys. The presence of salmonid species is encouraging and indicates the health of the river is good to support these species. Water quality is not a limiting factor to the fish populations of the River Lugg, as indicated by the Good or High status physchem determinant WFD classifications. Next survey Summer 2017

16 If you would like to discuss the information presented in this report, please contact: Libby Capps Environmental Monitoring Officer, Analysis and Reporting If you would like to discuss future management of this fishery, please contact: Brecht Morris Fisheries Officer. Fisheries, Biodiversity and Geomorphology Before you go fishing don t forget: You must have a valid Environment Agency rod licence and permission from the fishery owner; You must comply with the fisheries byelaws; The coarse fish close season (15th March to 15th June inclusive) applies to all rivers, streams and drains in England and Wales but not most stillwaters. Stillwater fishery owners can still have their own close season and rules, so please check with them before setting out. Report illegal fishing: If you see any fishing, netting or trapping you think may be illegal, please do not tackle it yourself. Call us immediately on and tell us: Exactly where the alleged offence is taking place; What is happening; How many people are involved and their descriptions; The registration numbers of any vehicles involved. If you prefer to remain report an environmental crime anonymously call Crimestoppers on or