Influence of Environmental and Spatial Variables on the Habitat Selection of Spiny Dogfish: Implications for Understanding the Species Life History Strategy and Management in the Northwest Atlantic

Seasonal and decadal movement patterns, environmental preference and distributional changes of spiny dogfish  (Squalus acanthias) were examined along the northeast continental shelf from 1963 to 2009. Data were obtained from annual autumn and spring bottom trawl surveys conducted by the National Marine Fisheries Service (NMFS). Influences of bottom temperature and salinity, depth, and latitude on distribution were investigated for male and female neonates (TL ≤ 26 cm), juvenile females (26 cm < TL < 80 cm), juvenile males (26 cm < TL < 60 cm), adult females (TL ≥ 80 cm) and adult males (TL ≥ 60 cm). Highly variable seasonal and decadal distributional trends were documented within stages. During spring significant (p ≤ 0.05) temperature, salinity and latitude associations were common for most stages while only neonates associated with depth. In contrast, no significant temperature associations occurred during autumn when dogfish were more aggregated. Autumn revealed significant (p < 0.05) associations for latitude (most stages), salinity (neonate, mature females and mature males), and depth (mature females). Stages differed considerably regarding preferred habitat during both seasons while some revealed decadal differences. Overall geographic range did not appear to be regulated by density-dependent mechanisms except for occupancy of several offshore strata in the western shelf. Increased knowledge of spiny dogfish behavior in relation to the environment can help reduce variability associated with survey indices and help reinforce stock assessments.