| dc.description | In the Barents Sea, capelin is a key food item for the North-East Arctic cod stock. This
capelin stock has had very unstable population dynamics since 1985, with recruitment
failures leading to three major collapses of the stock (>90% reduction of the stock size),
resulting in decreased growth and survival of cod. Here we analyze in detail how
predation and harvest affects the recruitment of capelin, using data on three different
stages (i.e., larvae, zero-group and 1-year-olds) through the first 1.5 years of the capelin's
life. We demonstrate that both herring predation (on capelin larvae) and cod predation
(both on spawners and on offspring) has had major negative effects on capelin
recruitment. Mortality is furthermore demonstrated to be strongly density-dependent, and
is lower when temperatures are high – probably due to higher food availability for
capelin. Harvesting maturing capelin on the way to the spawning grounds did affect the
production of larvae, at least during the first half of the 1980s. However, the reduced
production of larvae appears to a large extent to have been compensated by decreased
density-dependent mortality on later life-stages, resulting in only minor effects on the
abundance as 1-year-olds. Altogether, our study points to the importance of trophic
interactions in determining the dynamic structure in high-latitude marine ecosystems.
Keywords: stock collapse, predation, trophic interactions, harvesting, density-dependent
mortality, Generalized Additive Models (GAM) | no_NO |
