Why salmon are below parr

SCIENTISTS from the GWCT are donning waders and arming themselves with nets on their annual expedition to catch and tag as many young salmon on the river Frome as possible. every September for the past 13 years, researchers from the GWCT’S Salmon & Trout research Centre at east Stoke in Dorset have tagged about 10,000 juvenile salmon. Measuring just 12mm by 2mm, PIT tags enable staff to individually identify fish when they swim past detector antennae. Using monitoring equipment that’s been partly funded by Orvis, the scientists spend days in the river—where the number of atlantic salmon returning from the sea have been quantified for 45 years—catching, tagging and weighing salmon parr in the hope of working out why populations have been on the wane since the 1990s. ‘The more tags we can get in the river, the lower the uncertainty,’ says Dylan roberts of the GWCT fisheries team.

it’s widely believed that salmon numbers are adversely affected by problems in the marine environment, such as warmer sea temperatures. However, the GWCT’S work is significant as it monitors both salmon smolt output and returning adults.

Last year, the GWCT fisheries team received a boost in eu funding from the €€7.8 million SAMARCH initiative (Salmonid Management round the Channel; www.samarch.org). The project, which runs until 2022 and involves 10 partners from the UK and France, aims to encourage better management of atlantic salmon and sea trout in estuaries and coastal waters in the english channel and to learn more about what happens when they leave our rivers for the sea. PL