Distribution and some biological features of skate Bathyraja parmifera (Rajidae, Rajiformes) in the northwestern part of the Sea of Japan
In the northwestern part of the Sea of Japan, skate Bathyraja parmifera in catches of the bottom trawl occurs at depths of 40 to 830 m at the near-bottom temperature of 0.4–4.9°C. Throughout the year, the skate performs migrations within the continental slope and, in the feeding period, inhabits mainly the depth range of 300 to 500 m. Maximal average density of aggregations of B. parmifera is observed in waters of northern Primorye; minimal average density is observed in Peter the Great Bay and on the Yamato Bank. In catches, skates with a length of 17–130 cm and a weight of 0.5–18.8 kg are recorded; however, fish with a length of 80–115 cm dominate. Individuals with a length of up to 40 cm feed mainly on amphipods, and larger immature and adult individuals feed on decapods, cephalopods, and fish. The value of the daily ration of B. parmifera with its growth decreases from 2.4 to 0.9% of the body weight. Specific ecological features of B. parmifera are a cause of its considerable underfishing by the bottom trawl; therefore, the total resource of this species in the considered region may be at the level of maximal estimates obtained during surveys and comprise no less than 20000 t.
Ichthyofauna composition in the mesobenthal of Peter the Great Bay (Sea of Japan)
Based on our data, 76 species of fish from 57 genera and 19 families are found in the mesobenthal of Peter the Great Bay. At depths greater than 200 m in the open part of the bay, no less than five species occur that are lacking closer to the coast; twenty species are capable of descending to a larger depth than was previously assumed. The species composition of fish in the mesobenthal is impoverished during the period of the hydrological summer and is considerably enriched in the cold time of the year, which is related to the wintering migrations of many species from shelf waters to the continental slope. Mass, common, and rare, as well as permanently occurring fish are determined for each hydrological season. The lowest fish biomass is observed in the warm time of the year, and the highest in winter and spring. Specific features of the spatial and temporal variation in the composition of mass fish in the mesobenthal are shown.
The taxonomy of New Zealand skates (Suborder Rajoidea), with descriptions of three new species
Abstract Two species of Raja are known to occur in New Zealand waters. The common “rough” skate, usually referred to R. australis Macleay, 1884, or sometimes to R. lemprieri Richardson, 1846, is shown to be R. nasuta Banks in Muller and Henle, 1841. The “smooth” skate, usually referred to R. nasuta, has not in fact been named, and is now described as R. innominata n.sp. The rough skate, R. nasuta, is brownish above, usually marked with numerous small white spots and dark spots or blotches and a pair of dark ocelli; below it is predominantly white; dorsally it has prickles on most of the disc (females) or in a middorsal-trunk band (males) at all ages; ventrally the abdominal region lacks prickles except for a few in large females; the tail in medium to large specimens is relatively wide, usually with three rows of spines, and there are 56–57 predorsal-caudal vertebrae. The smooth skate, R. innominata, is greyish above, usually marked with several large dark spots; below it is predominantly grey; in subadul...