Distribution of cephalopods in the upper epipelagic northwestern Bering Sea in autumn

摘要

In the northwestern Bering Sea in autumn, the epipelagic cephalopod community was represented by the boreal fauna, and was found to be composed of three families and nine species of the order Teuthida: Gonatidae (Berryteuthis magister, Boreoteuthis borealis, Gonatopsis japonicus, Gonatus madokai, Gonatus kamtschaticus, Gonatus onyx, and Gonatus pyros), Chiroteuthidae (Chiroteuthis calyx) and Onychoteuthidae (Onychoteuthis borealijaponica). Two pelagic gonatid species (B. borealis and G. kamtschaticus) dominated the cephalopod community in the upper 50 m. The distribution patterns of B. borealis and G. onyx were associated with diel vertical migrations of these squid. The distribution of two distinct size groups of G. kamtschaticus suggested ontogenetic migration of larger squid to deeper layers, and adds to previous data suggesting that this species may be a heterogeneous assemblage. Demersal B. magister rarely occurred in the surface waters. The occurrence of maturing O. borealijaponica in the southern marine area indicated that these were occasional seasonal migrants from the ocean. The occurrence of juvenile C. calyx suggested that these squid may conduct vertical forage migrations from deep waters to the surface layers.