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dc.contributor.authorvan Leeuwen, Casper
dc.contributor.authorMuseth, Jon
dc.contributor.authorSandlund, Odd Terje
dc.contributor.authorQvenild, Tore
dc.contributor.authorVøllestad, Leif Asbjørn
dc.identifier.citationEcology and Evolution 2016nb_NO
dc.description.abstractHabitat fragmentation is a growing problem worldwide. Particularly in river systems, numerous dams and weirs hamper the movement of a wide variety of species. With the aim to preserve connectivity for fish, many barriers in river systems are equipped with fishways (also called fish passages or fish ladders). However, few fishways provide full connectivity. Here we hypothesized that restricted seasonal opening times of fishways can importantly reduce their effectiveness by interfering with the timing of fish migration, for both spring- and autumn-spawning species. We empirically tested our hypothesis, and discuss the possible eco-evolutionary consequences of affected migration timing. We analyzed movements of two salmonid fishes, spring-spawning European grayling (Thymallus thymallus) and autumn-spawning brown trout (Salmo trutta), in Norway’s two largest river systems. We compared their timing of upstream passage through four fishways collected over 28 years with the timing of fish movements in unfragmented river sections as monitored by radiotelemetry. Confirming our hypothesis, late opening of fishways delayed the migration of European grayling in spring, and early closure of fishways blocked migration for brown trout on their way to spawning locations during late autumn. We show in a theoretical framework how restricted opening times of fishways can induce shifts from migratory to resident behavior in potamodromous partial migration systems, and propose that this can induce density-dependent effects among fish accumulating in lower regions of rivers. Hence, fragmentation may not only directly affect the migratory individuals in the population, but may also have effects that cascade downstream and alter circumstances for resident fish. Fishway functionality is inadequate if there is a mismatch between natural fish movements and fishway opening times in the same river system, with ecological and possibly evolutionary consequences for fish populations.nb_NO
dc.rightsNavngivelse-Ikkekommersiell-DelPåSammeVilkår 3.0 Norge*
dc.subjectBrown trout (Salmo trutta)nb_NO
dc.subjecteco-evolutionary consequencesnb_NO
dc.subjectEuropean grayling (Thymallus thymallus)nb_NO
dc.subjectfish passage functionalitynb_NO
dc.subjectlife history strategynb_NO
dc.titleMismatch between fishway operation and timing of fish movements: a risk for cascading effects in partial migration systemsnb_NO
dc.typePeer reviewednb_NO
dc.typeJournal article
dc.subject.nsiVDP::Mathematics and natural science: 400nb_NO
dc.subject.nsiVDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488nb_NO
dc.source.journalEcology and Evolutionnb_NO
dc.relation.projectNorges forskningsråd: 179569nb_NO

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Navngivelse-Ikkekommersiell-DelPåSammeVilkår 3.0 Norge
Except where otherwise noted, this item's license is described as Navngivelse-Ikkekommersiell-DelPåSammeVilkår 3.0 Norge