A preliminary evaluation of migratory salmonids as vectors of organic carbon between marine and freshwater environments

This study is part of a larger investigation to obtain estimates of fluxes of various constituents transported by migrating salmonids in rivers in northeast England. Initial work has focussed on the River Tweed because it supports one of the largest populations of Atlantic salmon and sea-trout in the UK. Preliminary investigations for the 6 years, 1989–1994, have shown that the total annual carbon import via adults of both salmonid species varied from 26–35×103 kg in the poorest year to 28–40×103 kg in the best year. Total annual carbon export via smolts of both species varied from 2.2–2.9 × 103 kg in the poorest year to 3.7–4.5 × 103 kg in the best year.