GWCT Fish Counter records the earliest returning adult salmon to the River Frome in 20 years!
Luke Scott, Fisheries Research Assistant, at the GWCT Salmon & Trout Research Centre got a nice surprise when checking the video footage from the River Frome counter from the 14th February 2023.
This fish was not one tagged by the GWCT Fisheries Team before it migrated, so what we know about it is limited but here is what we can learn from the video footage.
We know this is a salmon, rather than a sea trout, because of its size and swimming behaviour. Salmon and sea trout demonstrate different swimming behaviour when challenged by fast flowing water, like that on the weir at the fish counter.
Based on the recorded size of 116cm, we know this salmon is a multi-sea-winter salmon. We can estimate that based on its size, it has spent three, possibly four, years at sea. It may even be a repeat spawner, meaning that it has already reproduced in freshwater before, returned to sea as a mended kelt and is returning again to reproduce for a second time.
Because this fish was not tagged as a juvenile, we can only guess at its freshwater age. However, our research tells us that >97% of salmon in the River Frome smolt and migrate to sea after one year, hence we estimate this salmon is most likely to be four years old.
This salmon will now spend the next 10+ months in the river, waiting to spawn around Christmas time. Incredibly it will not feed during that time in freshwater, but will look for somewhere cool and deep within the river to rest and preserve its energy.
But successfully returning to the river, does not necessarily mean this fish will successfully go on to spawn. There are numerous threats that it may face including natural predation by otters and more upsetting pollution events which effect the water quality of the environment it inhabits.
There is a salmon fishery on the River Frome which starts on the 1st March. However, a voluntary catch and release agreement is in place for the river, so anglers return the salmon caught, and minimise handling of the fish before doing so. Further protection from angling pressure is provided in the form of a bylaw for the Wessex area, which stipulates that salmon and sea trout fishing is by artificial fly only before 15th May. This ‘fly only’ rule early in the season was introduced to reduce the pressure on the big multi-sea-winter fish.
A high proportion of multi-sea-winter salmon are females, in which case this fish could be carrying 15,000+ eggs. We wish this salmon all the luck for the next 10 months and hope that he or she goes on to successfully spawn and contribute to the next generation of River Frome salmon.