A PRELIMINARY EVALUATION OF MIGRATORY SALMONIDS AS VECTORS OF ORGANIC-CARBON BETWEEN MARINE AND FRESH-WATER ENVIRONMENTS

This study is part of a larger investigation to obtain estimates of fl uxes of various constituents transported by migrating salmonids in riv ers 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 o f both salmonid species varied from 26-35 x 10(3) kg in the poorest ye ar to 28-40 x 10(3) kg in the best year. Total annual carbon export vi a smelts of both species varied from 2.2-2.9 x 10(3) kg in the poorest year to 3.7-4.5 x 10(3) kg in the best year. (C) 1997 Elsevier Scienc e B.V.