Distribution and some biological features of the Pacific sand lance Ammodytes hexapterus (Ammodytidae) in waters off Kamchatka in the Sea of Okhotsk

Abstract

Data on the spatiotemporal distribution, size-age structure, individual fecundity, and food composition of the Pacific sand lance Ammodytes hexapterus in waters off Kamchatka in the Sea of Okhotsk in the summer months are provided. It is shown that, on the western Kamchatka shelf, this species is found uniformly at depths smaller than 100 m in the range of temperatures from −0.83 to 9.45°C. Maximum catches (more than one to three thousand individuals per hour of trawling) are constantly recorded locally in the central part of the shelf (52°–56°N) in a comparatively narrow range of depths 20–60 m at temperatures of 1.5–8.0°C, mainly on sandy and sandy-pebbly grounds, which is related to a specific behavioral feature of A. hexapterus such as burrowing itself into the ground. It was established that in waters off Kamchatka in the Sea of Okhotsk, maximum sizes of A. hexapterus are 27 cm and 54 g (although its individuals with a length of 18–24 cm and a body weight of 20–40 g occur more frequently in catches); individual fecundity varies from 9.9 to 59.9 (on average, 29.7) thousand eggs. It was shown that, in waters off Kamchatka in the Sea of Okhotsk, unlike other habitats, the main food items of A. hexapterus (more than 95% by weight), besides copepods, are pelagic tunicates Oikopleura sp. and larval decapods at the megalope stage. With an increase in the size of A. hexapterus, the proportion of the former in its food decreases and, of the latter, increases.