Vol 59, No 5 (2019)

The Bean’s bigscale, S. beanii, is redescribed in the first part of the species revision of the genus Scopelogadus. Information on its morphological features is provided based on the material obtained from several areas of the World Ocean: the northern and southeastern parts of the Atlantic Ocean, from the waters adjacent to Australia, and from the southwest and southeastern parts of the Pacific Ocean. When comparing the fish from these areas, differences were found in a number of characters, probably indicating the presence of a subspecies. The species inhabits the North Atlantic Ocean in the Gulf Stream system, the East Atlantic Ocean, and the southern parts of the Atlantic, Indian, and Pacific oceans in the subtropical zone (between 30°–45° S). Habitat depths vary from 150 to 2000 m.

Changes in external morphological characters and relative lengths of vertebral centra from different regions of the vertebral column are analyzed during smoltification in wild juveniles of five salmonid fish species: Atlantic salmon Salmo salar, brown trout S. trutta, mikizha Parasalmo mykiss, coho salmon Oncorhynchus kisutch, and northern Dolly Varden Salvelinus malma. The changes in the body proportions and external morphology are similar in different salmonid species, but the patterns of differentiation of the vertebral column’s postanal part are different. In Atlantic salmon, all vertebral centra of the postanal part are subject to elongation; in mikizha and brown trout, a small number of the centra are elongated only in the anterior region of the postanal part; in coho salmon, the centra are elongated in the posterior region of the postanal part; in Dolly Varden, the centra are elongated in the middle region of the postanal part. Thus, despite observed universal changes in external morphology associated with smoltification in the family Salmonidae, the development of future marine migrants' phenotypes is species-specific due to different growth of various groups of vertebral centra in the vertebral column’s postanal part. The possible reasons for the species diversity in the growth of various groups of vertebral centra are discussed.

The larvae and/or juveniles of coastal species were found in the composition of oceanic ichthyoplankton sampled during the 43^rd expedition of R/V “Akademik Vavilov” in the southern waters of the North Atlantic. These fish included insufficiently-studied taxonomic forms from five families: Myripristis jacobus (Holocentridae), Ctenogobius sp., Gobionellus oceanicus, Gobioides grahamae (Gobiidae), Eleotris sp. 1., Dorminator maculatus (Eleotridae), Spariosoma sp. 1 (Scaridae), and Pontinus nematophthalmus, (Scorpaenidae). The paper presents illustrated descriptions of these forms and discusses the problems of their identification.

Life cycle and migration activity of sea demersal fishes throuout the seasons defines the formation of associated multispecies communities allocated on the restricted area of the shelf and the upper slope zone. They were characterized by some features like particular species structure, specific ratio between individual biomass within the group of dominant species, and their existence probably determined by similar preferences of the species in view of their spawning, feeding, and wintering sites. Annual appearance of communities allows one to trace their seasonal dynamics caused by the change in fish habitat during the perennial biological cycle and also species biomass dynamics associated with long-term periodical shift of fish resources in the area. Some revealed specific communities have been called “summer shallow-area,” “gadids,” “cottids,” and “flat-fishes” according to their dominant components. Peculiar features of these communities studied facilitate developing efficient multispecies fishery and, at the same time, to control the structure of the fish community in its quasi-random nature.

The data characterizing the number of separate generations of pink salmon Oncorhynchus gorbuscha and chum salmon O. keta on the northwest coast of Sakhalin Island (harvest volumes, entries of spawners into rivers and the subsequent downstream migration of the juvenile fish) are analyzed. According to the dynamics of harvests and biological indicators of fish, it has been shown that fishing is based on the approaches to the shore of different groups of these fish species. If the presence of groupings for chum salmon is associated with the migration of fish of different races (summer and autumn) and of different origin (from the Amur River and small rivers of the northwestern coast of Sakhalin and the adjacent mainland coast), then it is mainly due to the approach of fish of local origin but of different temporal forms for pink salmon.

This article describes early development of the climbing perch Anabas testudineus in relation to its buoyancy dynamics. Main patterns of the ontogeny during the first 140 h of development are described. The climbing perch is characterized by positive buoyancy of eggs and early larvae not usually found in other freshwater fish. This allows the fish development close to the surface of the water and is enabled by a large oil globule in the yolk. The data on the spatial orientation of the larva body, their vertical distribution in the water column, the beginning of exogenous feeding and locomotion, and the fright reaction of the larvae at different ages are presented. The most significant changes in the behavior of the climbing perch larvae are associated with changing the shape of the yolk sac, beginning to function as a provisional hydrostatic organ from about the 80s hour of development.

Complex ecosystem analysis which includes total abundance estimation of its members as well as their quantitative trophic relationships gives an insight to ecosystem structure, its dynamic and steadiness and allows to compare large marine ecosystems. In this paper we aim to reveal and quantify the seasonal dynamics of main trophic web components and to estimate nekton (fish and squids) food capacity throughout the summer-autumn in upper epipelagic layer of deep basins in the Western Bering Sea. We used nekton and plankton abundance data as well as nekton diet data obtained in June-October throughout 2003–2015. Log-transformed abundance were averaged by 10-day periods considering the probability of occurrence of given species. We have found that the total biomass of nekton and the species ratio showed severe changes within summer-autumn. Total biomass reached the maximum in August showing two- or three-time increase from early-summer and followed by the similar decrease in autumn. The total food consumption changed in the same way. However, the grazing pressure on prey was very low as the consumer/prey biomass ratio approached zero. In addition, we have recognized diet divergence both between species and within size group of one specie. We conclude that the spatio-temporal separation of mass nekton species and differences in their diet lead to alleviation of trophic competition and grazing pressure.

The effect of thiourea (exposure to 0.05% solution) on the migratory activity of the climbing perch Anabas testudineus has been studied. It is established that thiourea simultaneously affects two components of the migratory behavior of climbing perch: rheoreaction and frequency of jumps out of water. Thiourea stimulates (by 27%) movement of specimens against the current and increases (by 31%) the frequency of jumps out of water. The effect of the substance is manifested on the fifth day of exposure, while specimens almost completely stop feeding on the twelfth day. Starvation caused by thiourea may play a crucial role in the effect of thiourea on the migratory activity of climbing perch.

The type series of Cheilopogon olgae Parin, 2009, is reinvestigated. In the original description of the species, some differences in morphological characters and in label data of type specimens are found. Corrected label data of the paratypes and the map on species distribution of the subgenus Ptenichthys in Australian waters are presented.

The present paper reports one reef associated fish species of the family Pomacanthidae, Apolemichthys xanthurus (Bennett, 1833) for the first time from the Andhra Pradesh coast. The specimen was collected from Kumbhabhishekam fishing harbour, Kakinada. Current manuscript deals with species description, morphometric and meristic characters to record its occurrence along Andhra Pradesh coast.