Biological features of the sea raven Hemitripterus villosus (Hemitripteridae) in Pacific waters off the northern Kuril Islands and southeastern Kamchatka

Data on the spatial-bathymetric distribution and the size-weight composition of the sea raven Hemitripterus villosus in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are provided. This representative of the family Hemitripteridae is a comparatively scarce, large fish species (maximum length 75 cm, body weight 11.8 kg), which in the study period (1992–2002) was found practically everywhere at the site from 48°00′ to 52°00′ N in the depth interval of 83–496 m at near-bottom temperatures from ?1.2 to 3.5°C. However, during the year, the overwhelming majority of its individuals were recorded in two depth ranges—101–150 and 251–400 m, which is accounted for by seasonal changes in the habitation depths. With an increase in depth, the sizes of H. villosus increase in catches due to the fact that individuals with a body weight smaller than 1.7–1.9 kg reside mainly at depths of up to 300 m, and those with a body weight greater than 2.2–3.0 kg reside at larger depths. It is demonstrated that the occurrence and the amount of catches of H. villosus are subjected to some interannual, seasonal, and diurnal dynamics.