Food web dynamics affect Northeast Arctic cod recruitment

Abstract

Proper management of ecosystems requires an understanding of both the species interactions as well as the effect of climate variation. However, a common problem is that the available time-series are of different lengths. Here, we present a general approach for studying the dynamic structure of such interactions. Specifically, we analyse the recruitment of the world's largest cod stock, the Northeast Arctic cod. Studies based on data starting in the 1970-1980s indicate that this stock is affected by temperature through a variety of pathways. However, the value of such studies is somewhat limited by the fact that they are based on a quite specific ecological and climatic situation. Recently, this stock has consisted of fairly young fish and the spawning stock has consisted of relatively few age groups. In this study, we develop a model for the effect of capelin (the cod's main prey) and herring on cod recruitment since 1973. Based on this model, we analyse data on cod, herring and temperature going back to 1921 and find that food-web effects explain a significant part of the cod recruitment variation back to around 1950.

Optimal Management Under Institutional Constraints: Determining a Total Allowable Catch for Different Fleet Segments in the Northeast Arctic Cod Fishery

“…For NEA cod, the most important environmental factors are interactions with other species and climate, in particular temperature (Ottersen et al 2006;Hjermann et al 2007). There are several channels through which climate may affect cod recruitment (Kjesbu et al 2014).…”

“…However, for NEA cod temperature affects very young individuals differently than old ones, making the overall effect on the population somewhat ambiguous (Kjesbu et al 2014). Second, warmer years may lead to enhanced recruitment independent of the size of stock biomass (Hjermann et al 2007). Third, a warmer climate may increase the carrying capacity, which is effectively facilitated by a range expansion into Northern waters (Ottersen et al 1998;Kjesbu et al 2014).…”

Spring phenological responses of marine and freshwater plankton to changing temperature and light conditions

“…Plankton blooms are important features in seasonal aquatic environments where they drive many ecosystem and community processes and are a major source of energy input for higher trophic levels (Hjermann et al 2007;Smayda 1997;Winder and Cloern 2010). Seasonal plankton succession is a community phenomenon that is controlled by processes that regulate population dynamics of various primary producers and consumers (Sommer et al 1986).…”

Global connectivity and cross-scale interactions create uncertainty for Blue Growth of Arctic fisheries

“…of the region is composed mainly of capelin (Mallotus villosus), herring (Clupea harengus) and polar cod (Boreogadus saida). Capelin, the biomass of which is highly fluctuating is the main prey of many fishes, including the Barents Sea cod [38]. The Barents Sea biological production, across trophic levels, is highly dependent on the ecosystem processes of the adjacent Norwegian Sea [39].…”