Age, sex ratio and timing of the catch of kelts and ascending Atlantic salmon in the subarctic River Teno

By 15 June, 82% of the catch of Atlantic salmon Salmo salar kelts had been taken from the middle part of River Teno, northern Scandinavia. The median date of capture was 4 June for males and 8 June for females. Salmon of 1-4 sea-winters (SW) of both sexes survived spawning to return to sea as kelts. Among males, 1 SW kelts were caught earliest in the spring and 3 SW latest, but among females 4 SW were earliest, then 3 SW and finally 1 and 2 SW. There were 17 river and sea-age combinations among the kelts compared with 23 among the ascending salmon. The smolt age distribution and the mean smolt age differed significantly only between female 2 SW ascending salmon (3.97 years) and kelts (4.14 years). The proportion of 1 SW females was higher and that of 3 SW males lower among kelts than among ascending salmon. The proportion of males among 1 SW ascending salmon was 80% but among kelts only 57%. Similarly, the proportion of males among 3 SW fish was 21% for ascending salmon but only 7% for kelts. Hence overwinter mortality was higher among males. Male and female kelts of 1 and female kelts of 2 SW had a greater mean length than ascending salmon in corresponding groups indicating a better survival of larger fish within an age group. Grilse ascend rivers after most kelts have left, but the main catch of ascending 2-3 SW salmon takes place concurrently with kelts leaving the river, inadvertently targeting kelts in the fishery. (C) 2000 The Fisheries Society of the British Isles.