The Game & Wildlife Conservation Trust has just published its latest report on Atlantic salmon monitoring on the river Frome in Dorset. The report gives fascinating insight on the rise and fall of salmon populations on this typical lowland chalk stream during some of the most extreme weather conditions in its 41 year history of monitoring.
Despite the weather conditions, the report identifies that 2013 was a good year for Frome salmon smolts reflected in the high numbers of parr recorded the previous September. However, for the adults returning to the rivers from the sea to spawn it was a very poor year with only 343 fish counted (compared to over 1,400 returning fish in 2011). This is the lowest number ever recorded by the team of researchers, who are investigating their long-term data to gain a better understanding of how extreme conditions affect this fascinating species.
Dylan Roberts, from the GWCT’s Salmon & Trout Research Centre at East Stoke said, “Understanding how extreme flooding impacts on salmon is complicated and can affect them in many ways during their life-cycle. Our long-term data helps us to understand these factors better, which in turn can help us improve their survival in the freshwater phase of their life-cycle.”
To gain further insight on the plight of this iconic species, which has declined by 70 per cent over the past three decades, the GWCT fisheries scientists on the river Frome are collaborating with French scientists from the National Institute for Agricultural Research (INRA) in Brittany.
This cross-border project called Morfish (Monitoring for Migratory Fish) is funded by the EU Interreg IV4A Channel Area programme and will run until June 2015. The aim of Morfish is to ensure that data from the three rivers – Rivers Frome in Dorset, the Oir in Normandy and the Scorff in Brittany – are collected in a similar way to facilitate their combined analysis. This will help us to better understand drivers underlying changes in our populations of migratory fish, particularly Atlantic salmon.
Both partners have recently completed their annual monitoring of the young salmon’s migration as they leave their rivers in the spring for the sea as smolts. In one to three years’ time, the surviving fish from this year will be counted as they return to their natal river as adults to spawn.
Dylan Roberts reports that the size of the smolt run on the River Frome this year was slightly smaller than normal with approximately 9,000 fish recorded as opposed to the an average of 11,000 over the last nine years. However, the smolt run on the Scorff proved to be better with around 10,000 young fish leaving the river and heading for the North Atlantic feeding grounds. Analysing these slight differences can be crucial in gaining further insight on fish survival both in the river and in the marine environment.
In addition, the fish scientists discovered that both English and French rivers experienced an earlier migration than normal probably caused by a mild winter followed by high flows in the spring.
Dylan Roberts said, “This early migration could have future implications on their survival and performance at sea. We are not sure what this could mean in the long term, but a crucial element of our Morfish collaboration will be to gain a better understanding of these factors to better manage these iconic fish.”
To obtain a copy of the GWCT’s 2013 salmon research report, please contact Daniel O’Mahony on 01425 651060 or download a copy from the GWCT’s website: www.gwct.org.uk/salmonreport2013
For further information on the MorFish project please visit www.morfish.org.uk.
For more information, please visit this website www.gwct.org.uk