Specific features of distribution and ecology of two species of armorhead sculpins of the genus Gymnocanthus (Cottidae) in Pacific waters of the northern Kuril Islands and Southeastern Kamchatka

Abstract

Based on materials of 1992–2012, data on the occurrence, spatial-bathymetric distribution, and size-weight composition of armorhead sculpin Gymnocanthus galeatus and purplegray sculpin G. detrisus and species accompanying them in catches in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are provided. These comparatively numerous, medium-sized representatives of the family Cottidae (maximal length of the former species 49 cm, weight 1400 g and that of the latter, 48 cm and 1140 g) in the period of study occurred uniformly at depths of 76 to 596 m at a near-bottom temperatures of −1.2 to + 4.5°C. Their maximum by density concentrations were constantly recorded at the beam of the Fourth Kuril Strait, from the oceanic side of the Paramushir and Shumshu Islands, and off the southeastern extremity of Kamchatka mainly in the lower part of the shelf (depths of 80–200 m) at temperatures of −1.0 to +2.5°C. Regularities of spatial-bathymetric distribution of different size groups of these species were analyzed. It was shown that the occurrence and the size of catches of both armorhead sculpins in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are subjected to some inrterannual, seasonal, and diurnal dynamics.