Open AccessChanges in selection and evolutionary responses in migratory brown trout following the construction of a fish ladder
Author(s) -
Haugen Thrond Oddvar,
Aass Per,
Stenseth Nils Christian,
Vøllestad Leif Asbjørn
Publication year - 2008
Publication title -
evolutionary applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.776
H-Index - 68
ISSN - 1752-4571
DOI - 10.1111/j.1752-4571.2008.00031.x
Subject(s) - brown trout , biology , salmo , fishing , trout , fishery , fish migration , catch and release , population , waterfall , ecology , selection (genetic algorithm) , salmonidae , natural selection , fish <actinopterygii> , geography , demography , recreational fishing , archaeology , artificial intelligence , sociology , computer science
Brown trout ( Salmo trutta ) are extensively harvested and its habitat highly influenced by human encroachments. Using a 40‐year time series of mark–recapture data we estimate vital rates for a piscivorous trout population. This population spawns upstream of a waterfall, which historically acted as a migration barrier for smaller trout. In 1966, the waterfall was dammed and a fish ladder constructed. All fish ascending the fish ladder were individually tagged and measured for a variety of traits. The fish ladder overall favoured access to upstream spawning areas for middle‐sized trout, resulting in stabilizing selection acting on size at spawning. Over time, natural and fishing mortality have varied, with fishing mortality generally decreasing and natural mortality increasing. The average and, particularly, variance in size‐at‐first‐spawning, and growth rates during the first years of lake residence have all decreased over the 1966–2003 period. These changes are all consistent with a shift from directional to stabilizing selection on age and size at spawning. Estimated rates of phenotypic change are relatively high, in particular for size at first spawning, adding further support for the growing notion that human interference may lead to rapid life‐history trait evolution.