now available to download as a PDF.
The abstract from the report is below:
2013 was the 41st year of the salmon counter’s operation at East Stoke. It was an extremely good year for the juvenile phases of salmon with high numbers of every life stage being recorded. For the adults it was very poor. Parr numbers in the river in September 2012 were very good: the third highest since 2002 and the number of autumn migrant parr that went past East Stoke was high: the second highest we have recorded. The spring monitoring of smolts was excellent and, at over 13,000, was over twice the number recorded in 2012.
On the adult count, equipment failure meant that some data that we normally collect on salmon movement was lost. For this reason we have added an efficiency estimate to the collected data to give an estimated nett upstream count of 343 fish.
This is the lowest number ever recorded on the counter. Adult numbers calculated from PIT tag returns give an estimate very similar to this (383) so we are confident that the numbers were low. This low number of adults is also in agreement with our prediction last year about low numbers of grilse returning this year.
The collaboration with the Poole Harbour netsman continues with only one sea trout caught, tagged and released in 2013.
Our research (with Cefas) on the effect of using rotary screw traps to assess salmon smolt numbers was completed and results will be analysed and written up as soon as possible. The research on the medium and long-term effect of Archimedes screw turbines on salmon smolts and eels also got underway using the facility at Bindon Abbey.
Our current Passive Integrated Transponder (PIT) tag detection equipment is getting very fragile and the manufacturer is no longer supplying new equipment. After reviewing available options we have found sponsorship and funding to replace the readers with new ‘state of the art’ equipment. The new detectors will be better able to withstand the high river flows we have recently experienced and installation should take place this summer.
Mean annual discharge (up to December) was above average, however, the mean monthly discharge in January 2014 was the highest ever recorded for that month.
Finally we are continuing to work with our French colleagues at INRA in Rennes, France, on the Monitoring for Migratory Fish (MorFish) project which will compare data to give us a better understanding of the changes in our populations of migratory fish.
Professor Nick Sotherton
Director of Research, Advisory & Education
Download GWCT 2013 Salmon research report >