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Influence of environmental and biological factors on the overwinter growth rate of Atlantic salmon Salmo salar parr in a UK chalk stream
Author(s) -
Simmons Olivia M.,
Britton John Robert,
Gillingham Phillipa K.,
Gregory Stephen D.
Publication year - 2020
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12542
Subject(s) - overwintering , salmo , juvenile , temperate climate , fishery , biology , ecology , growth rate , range (aeronautics) , environmental science , fish <actinopterygii> , materials science , geometry , mathematics , composite material
Smolt lengths are increasingly recognised as an important determinant of salmonid marine survival rates. Overwintering growth rates could thus strongly influence adult return rates. In Atlantic salmon Salmo salar , most overwintering studies focus on rivers in harsh climates with minimal growth, yet in more southerly rivers, overwintering growth rates can be relatively high. Here, the factors influencing annual overwinter growth rates were tested for juvenile S. salar in a temperate chalk stream in southern England over 13 years, where over 10,000 salmon parr were tagged annually in autumn and a proportion recaptured the following spring during smolt emigration. Winters of higher and more variable water temperatures, with longer periods of high flows, showed increased overwintering growth rates. Faster growth rates were recorded from sites further upstream and that had lower parr densities; smaller individuals also grew more than expected for their initial size. These results suggest that a range of factors influences overwintering salmonid growth rates and can be used to inform management decisions to maximise the quality of emigrating smolts.