A length-based hypothesis for feeding migrations in pelagic fish

Abstract

Abstract:We evaluated the costs and benefits of long-distance horizontal migration by pelagic planktivores, Atlantic herring (Clupea harengus), blue whiting (Micromesistius poutassou), mackerel (Scomber scombrus), and capelin (Mallotus villosus) in the Norwegian and Barents seas using a numerical model and tested model predictions against field observations. Specifically, we considered (i) energetic costs as a function of body size, water currents, swimming speed, and distance, (ii) time costs as a function of speed and distance, and (iii) energetic gain in terms of differences in food intake between areas. The model demonstrates how body size restricts large-scale horizontal migration patterns. Model and field results suggest that the extent of migration will increase with increasing body length. The model predicts that long-distance migration costs may exceed energy intake for fish <20 cm, due to increased hydrodynamical drag with decreasing fish size. Field results suggest that migration distance is a function of length, weight, and age. Food abundance and distribution, current speed and direction, and differences in day length at boreal latitudes are believed to be the major driving forces influencing large-scale migration distance, direction, and timing in pelagic planktivores. Northwards latitudinal rather than longitudinal feeding migrations are explained by the improved feeding opportunities with increased day lengths.Résumé : Nous avons évalué les coûts et les avantages de la migration horizontale à longue distance de poissons pélagiques planctivores, à savoir le hareng (Clupea harengus), le merlan bleu (Micromesistius poutassou), le maquereau (Scomber scombrus) et le capelan (Mallotus villosus), dans la mer de Norvège et la mer de Barents. Nous avons comparé les prévisions obtenues d'un modèle numérique et d'un modèle fondé sur les observations aux valeurs observées sur le terrain. Plus précisément, nous avons examiné (i) les dépenses énergétiques en fonction de la taille, du courant, de la vitesse de nage et de la distance, (ii) les dépenses de temps en fonction de la vitesse et de la distance et (iii) le gain énergétique en fonction des écarts de la consommation alimentaire entre les zones. Le modèle montre comment la taille limite la migration horizontale à grande échelle. Le modèle et les résultats obtenus sur le terrain portent à croire que l'importance de la migration s'accroît avec la longueur du poisson. Selon le modèle, les coûts d'une migration sur une longue distance peuvent être supérieurs à l'énergie absorbée chez les poissons de moins de 20 cm de longueur, étant donné que la traînée hydrodynamique s'accroît à mesure que la taille du poisson décroît. Les résultats obtenus sur le terrain indiquent que la distance de migration est fonction de la longueur, du poids et de l'âge. L'abondance et la répartition de la nourriture, la vitesse et la direction du courant de même que la durée du jour, différente sous les latitudes boréales, semblent constituer les principales forces qui influent sur la...

Migration patterns in Norwegian spring-spawning herring: why young fish swim away from the wintering area in late summer

“…This may confine young herring primarily to coastal areas. Older herring could afford the costs of migrating out of the area and thus take advantage of higher concentration of food in offshore areas avoiding intra-specific competition in coastal areas (Nøttestad et al 1999). The results in the present study also supports that young herring trade-off food availability and migration costs differently than older co-specifics.…”

“…Young herring have higher migration costs than older herring (Nøttestad et al 1999), and should thus have different behavioural trade-offs. This may confine young herring primarily to coastal areas.…”

“…Food availability in coastal areas is high early in the feeding period (Melle et al 1994) and in years with a small herring stock (1970s and 1980s) this situation can prevail. It would then be advantageous for both young and old herring to keep the migration costs low by staying near the coast throughout the summer (Nøttestad et al 1999).…”

“…Norwegian spring-spawning herring has a high migratory capacity (Nøttestad et al 1999). The migration from the feeding area near Spitsbergen and Bjørnøya to the wintering area east of Iceland in 1968 was reported to start at the beginning of September, covering the Bjørnøya to Jan Mayen distance (~740 km) in 20 d (Jakobsson 1969), and Røttingen & Røttingen (1991) estimated that herring moved up to 830 km in 2 to 3 wk during the spawning migration.…”

Overlap in distribution and diets of Atlantic mackerel (Scomber scombrus), Norwegian spring-spawning herring (Clupea harengus) and blue whiting (Micromesistius poutassou) in the Norwegian Sea during late summer

“…Extensive numbers of pelagic planktivorous fish enter the Norwegian Sea during spring and summer to feed (Belikov et al 1998;Monstad et al 1998;Nøttestad et al 1999;Prokopchuk & Sentyabov 2006). An estimated average of 17 million tons of the dominating Atlantic mackerel (Scomber scombrus Linnaeus, 1758), Norwegian spring-spawning herring (Clupea harengus Linnaeus, 1758), and Atlantic blue whiting (Micromesistius poutassou Risso, 1827) are widely distributed in the Norwegian Sea (Anonymous 2010) in July.…”