Fish Ageing Survey Report The Gall Pond Our Ref: 14#194 Date:November 2014

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1 Fish Ageing Survey Report Our Ref: 14#194 Date:November 214 About this water is a 2.25 acre match/pleasure fishery with an average depth of around 7 feet. The water was sampled between April and July 214. The lake holds a variety of cyprinid species, predominantly common carp, also including roach, rudd, tench and common bream. Eels and the native predator perch are also present. Summary of age data In total, 13 scales were sampled from the lake. Of these, 9 fish were aged, with 13 being replacement scales. Scales that are lost from a fish are rapidly replaced, but do not contain the full growth record on them, making age determination impossible. There were 3 roach, 4 common bream, 7 rudd, 8 tench and 5 perch aged. The roach were aged to 9+, the rudd to 11+, the common bream to 14+ and the tench were aged to 22+. Additionally, perch were aged to 4+. Graph 1. Number of roach, rudd, common bream, tench and perch from Gall Pond with their size ranges CBr RO RU TE PE Length (mm)

2 Average Length at Age As a part of our examination of fish scales, we can measure the mark ( annulus ) which shows the end of each year on the scales. We can then work out how long each fish was at the end of each year's growth. From this, we can calculate the average length at each age. The table below shows the estimated average length of the common bream, roach and perch sampled from Gall Pond. Age Tench Length mm C. bream Length mm Rudd Length mm Roach Length mm Perch Length mm Percentage standard Growth values The average length at each age for the roach from Gall Pond was compared to the species standard (National Fisheries Service, unpublished data). The Percentage Standard Growth (PSG) values were calculated to be 91% where 1% is the National average. This means that overall they have an average growth rate. Graph 2 shows the mean length at age for the roach. The common bream had a PSG of 88% when compared to their species standard (Hickley and Dexter 1979). Overall the common bream had a slow growth rate, with the mean length at age shown in graph 3. The perch also showed average growth when compared to their species standard (National Fisheries Service, unpublished data) with a PSG of 1% (Graph 4). It is a consideration that there were very few perch in this sample and are within a narrow age range, the results are not very strong for this species but included for completeness. The sampled rudd showed very slow growth with a PSG of only 62%. Graph 5 shows the comparison to the species standards (McCafferey unpublished data 1995). There are no current growth standards for tench so we were unable to measure the growth performance of tench in Gall Pond. Graph 6 shows the mean length at age for the tench just without a standard line to compare it to. PSG values of between 9-11% are typically classed as average, slow is growth indicated by values of less than 9% and fast growth having PSG values of greater than 11%.

3 Length (mm) Length (mm) Graph 2. Growth rate of roach from Gall Pond compared to the national standard growth rate for roach (National Fisheries Service Unpublished Data) Fast Average Slow Very Slow Graph 3. Growth rate of common bream from compared to the national standard growth rate for common bream (Hickley and Dexter 1979) Average

4 Length (mm) Length (mm) Graph 4. Growth rate of perch from Gall Pond compared to the national standard growth rate for roach in the South (National Fisheries Service Unpublished Data) Fast Average Slow Very Slow Graph 5. Growth rate of rudd from Gall Pond compared to rudd in rivers (McCafferey 1995) 25 2 Average

5 Length (mm) Graph 6. Growth rate of tench from Gall Pond The Gall Pond Findings and Recommendations The roach appeared to be growing normally with a PSG within the average zone. Roach are a good indicator of a waters ability to support a healthy fish population. The results are similar to last year s report with a similar sample size and range of roach improving the confidence of these results. The small drop of 5% in growth (96%-91%) is normal through slight sample variation. The common bream were growing below the expected level. It is possibly significant most bream were in the larger size category although the sample size was greater than that for any other species. One possible reason for the slow growth is larger bream will often compete with carp for resources. The difference in PSG is quite marked in the bream with slightly over 2% reduction however these bream were significantly older and larger than the ones seen last year. The sample size last year was a lot smaller with only 12 common bream sampled compared to 4 this year. The rudd are showing very poor growth and as with the perch (below) the small sample size may not be representative of the population. Aslo the rudd were from quite a narrow age range of older fish 8+ to 11+ this could be due to sampling bias from rod and line but may indicate poor recruitment perhaps due to lack of habitat such as reeds and weed. We did not see any rudd in the previous sample last year. The tench look to be growing at a reasonable rate and the growth curve does not slow as they get older it is usual for normal growth to slow as the fish get older. Without a species standard for tench it is not possible to confidently comment on their performance.

6 The perch were growing at precisely the expected rate for this species in rivers. The small sample size and narrow size range means the perch may not represent the perch population as a whole in. The larger perch that seemed to be growing well last year were not present in this years survey. As a native predator, they often play a vital role in controlling juvenile cyprinid numbers, creating more space and food availability for those left to proliferate and grow well. It is advised that the perch remain in the lakes, for this purpose. If you require any further advice on managing your fishery please contact your local area officer Jody Armitage on Ageing Notation Plus (+) notation is used when the fish have been sampled between April to September and show summer growth. When fish are sampled during the period October to March they are aged by counting the edge of the scale as the end of the previous growing season. The age is, therefore, given in terms of a full year with no plus notation. Plus notation is used when the fish have been sampled between April to September and show summer growth.

7 Fish mm common bream 4+ = annulus National Fisheries Services - Fish Health, Ageing and Species, Environment Agency, Bromholme Lane, Brampton, Huntingdon, PE28 4N. Tel: ; Fax: ; fish.ageing@environment-agency.gov.uk