Distribution, biology, and relative abundance of the understudied deep-water whiteblotched skate Bathyraja maculata

Abstract

Our extensive research spanning four decades (1979–2023) investigated the spatial and vertical distributions, dynamics of catch rates (CPUEs), and basic biological features of the understudied deep-water species whiteblotched skate (Bathyraja maculata), which inhabits the North Pacific Ocean. The data used in our study were gathered from publicly accessible databases such as OBIS, GBIF, and AFSC and supplemented by the results of Russian bottom trawl surveys. Our investigation revealed regions with the densest aggregations of whiteblotched skate, notably along the eastern Bering Sea slope, off the Aleutian Islands, in the eastern Sea of Okhotsk, and in the Pacific waters off southeastern Kamchatka and the northern Kuril Islands. Typically, these areas showed the greatest abundance of this species at depths ranging from 400 to 700 m. Remarkably, whiteblotched skates exhibited a migratory pattern toward greater depths during colder months for overwintering, while in the warm period, they predominantly fed at shallower depths. The species also displayed a strong preference for bottom temperatures in the range of 3.1–4.5 °C. Individual whiteblotched skates had a total length spanning from 18 to 127 cm, with the bulk falling within the 50–100 cm range. An intriguing observation was the absence of significant differences in length and body weight between males and females. Additionally, our data revealed that condition factor values reached their peak during the autumn–winter period. Over the years, we observed a substantial increase in the catch rate of whiteblotched skates across most parts of their range. In these areas, the catch rates (CPUEs) initially decreased from the 1980 s to the early 2000 s before increasing.