E. Niemela et al., Age, sex ratio and timing of the catch of kelts and ascending Atlantic salmon in the subarctic River Teno, J FISH BIOL, 56(4), 2000, pp. 974-985
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. T
here were 17 river and sea-age combinations among the kelts compared with 2
3 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 a
nd that of 3 SW males lower among kelts than among ascending salmon. The pr
oportion 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 ascendi
ng salmon but only 7% for kelts. Hence overwinter mortality was higher amon
g 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 bett
er 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 p
lace concurrently with kelts leaving the river, inadvertently targeting kel
ts in the fishery. (C) 2000 The Fisheries Society of the British Isles.