Influence of environmental, spatial, and ontogenetic variables on habitat selection and management of spiny dogfish in the Northeast (US) shelf large marine ecosystem

Declines in abundance of commercially valuable groundfish have highlighted the ecological and commercial importance of previously underutilized elasmobranchs in the Northeast (US) shelf large marine ecosystem (NES LME). Seasonal distributions and ontogenetic habitats of one such species, spiny dogfish (Squalus acanthias), were investigated using Northeast Fisheries Science Center (NEFSC) bottom trawl survey data (1963-2009). Neonate, immature, and mature dogfish all selected warmer, more saline, and more southerly locations during spring compared with available locations. During autumn, larger dogfish occupied relatively warmer, shallower, and less saline waters while neonates selected higher salinities. There were strong ontogenetic patterns in habitats occupied. Contrary to expectation, geographic range contracted as abundance increased during autumn. This suggests that niche constraints override density-dependent effects, although detection of relationships within stages was limited by low statistical power. The proportion of mature female survey catch within the Mid-Atlantic Bight was significantly related to temperature, suggesting that environmental conditions surveyed may impact population trends. Collectively, these results highlight critical habitats, suggest mechanisms behind ontogenetic habitat selection, and provide insight into how changing environmental conditions may impact stock assessment. Les baisses d'abondance de poissons de fond a valeur commerciale soulignent l'importance ecologique et commerciale d'elasmobranches auparavant sous-utilises dans le grand ecosysteme marin de la plateforme continentale du nord-est des Etats-Unis (NES LME). Les repartitions saisonnieres et les habitats ontogeniques d'une de ces especes, l'aiguillat commun (Squalus acanthias), ont ete examines a la lumiere de donnees de releves au chalut de fond (1963-2009) du Northeast Fisheries Science Center (NEFSC). Parmi les sites disponibles, les aiguillats nouveau-nes, immatures et matures choisissaient tous des emplacements relativement chauds, salins et meridionaux au printemps. A l'automne, les aiguillats plus grands occupaient des eaux relativement chaudes, moins profondes et moins salines, alors que les nouveau-nes choisissaient des eaux de plus forte salinite. L'occupation des habitats definissait des motifs ontogeniques marques. Contrairement aux attentes, l'aire de repartition geographique diminuait parallelement a l'augmentation de l'abondance a l'automne, ce qui donne a penser que les contraintes touchant a la niche l'emportent sur les effets dependants de la densite, bien que la faible efficacite statistique limite la detection de relations pour des stades donnes. La proportion de femelles matures capturees dans le cadre des releves dans le golfe Medio-atlantique etait significativement reliee a la temperature, donnant a penser que les conditions ambiantes pourraient avoir une incidence sur les tendances des populations. Collectivement, ces resultats font ressortir des habitats essentiels et des mecanismes possibles de selection d'habitats ontogeniques et jettent un eclairage sur l'incidence de l'evolution des conditions ambiantes sur l'evaluation des stocks. [Traduit par la Redaction]
Introduction Understanding the habitat preferences of marine fishes is important when describing their spatial distribution and ecology (Perry and Smith 1994; Smith and Page 1996; Shepherd et al. 2002) and [...]