title: Life history variation in Barents Sea fish: implications for sensitivity to fishing in a changing environment.
abstract: Under exploitation and environmental change, it is essential to assess the sensitivity and vulnerability of marine ecosystems to such stress. A species' response to stress depends on its life history. Sensitivity to harvesting is related to the life history "fast-slow" continuum, where "slow" species (i.e., large, long lived, and late maturing) are expected to be more sensitive to fishing than "fast" ones. We analyze life history traits variation for all common fish species in the Barents Sea and rank fishes along fast-slow gradients obtained by ordination analyses. In addition, we integrate species' fast-slow ranks with ecosystem survey data for the period 2004-2009, to assess life history variation at the community level in space and time. Arctic fishes were smaller, had shorter life spans, earlier maturation, larger offspring, and lower fecundity than boreal ones. Arctic fishes could thus be considered faster than the boreal species, even when body size was corrected for. Phylogenetically related species possessed similar life histories. Early in the study period, we found a strong spatial gradient, where members of fish assemblages in the southwestern Barents Sea displayed slower life histories than in the northeast. However, in later, warmer years, the gradient weakened caused by a northward movement of boreal species. As a consequence, the northeast experienced increasing proportions of slower fish species. This study is a step toward integrating life history traits in ecosystem-based areal management. On the basis of life history traits, we assess the fish sensitivity to fishing, at the species and community level. We show that climate warming promotes a borealization of fish assemblages in the northeast, associated with slower life histories in that area. The biology of Arctic species is still poorly known, and boreal species that now establish in the Arctic are fishery sensitive, which calls for cautious ecosystem management of these areas.
authors.affiliation: Norwegian College of Fishery Science, University of Tromsø 9037, Tromsø, Norway.
authors.forename: Magnus A
authors.initials: MA
authors.lastname: Wiedmann
authors.affiliation: Department of Marine and Arctic Biology, University of Tromsø 9037, Tromsø, Norway.
authors.forename: Raul
authors.initials: R
authors.lastname: Primicerio
authors.affiliation: Knipovich Polar Research Institute of Marine Fisheries and Oceanography 6 Knipovich Street, 183038, Murmansk, Russian Federation.
authors.forename: Andrey
authors.initials: A
authors.lastname: Dolgov
authors.affiliation: Department of Marine and Arctic Biology, University of Tromsø 9037, Tromsø, Norway.
authors.forename: Camilla A M
authors.initials: CA
authors.lastname: Ottesen
authors.affiliation: Norwegian College of Fishery Science, University of Tromsø 9037, Tromsø, Norway.
authors.forename: Michaela
authors.initials: M
authors.lastname: Aschan
keywords: Areal management; Barents Sea; biogeography; climate change; fast–slow continuum; fisheries; phylogeny