Biological features of the common fish species in Olyutorsky-Navarin region and the adjacent waters of the Bering Sea: 4. family sculpins (Cottidae)

Based on the materials of investigations conducted for 20 years (1995?2015), the features of biology of the common fish species of the family Cottidae from the northwestern Bering Sea are studied. These species are found during summer and fall in the waters of the Olyutorsky-Navarin region. The size–age parameters of the fishes collected with different fishing gears, as well as the features of their body length and body weight dynamics, spawning time, and spawning conditions, are described. The largest exemplars of shorthorn sculpin Myoxocephalus verrucosus and staghorn sculpins, armorhead sculpin Gymnocanthus galeatus and G. detrisus, are recorded in the catches of snurrevads, while the fishes caught in trawls are characterized by smaller size. Interannual variability of the size composition of the fish is related to the abundance of certain generations or to the fishery directed to different associations of sculpins. In the coastal waters, comparatively low average body size is usual for the majority of common sculpin species (with the exception of lords, yellow Irish lord H. jordani and Gilbert’s Irish lord H. gilberti) because of the dominance of juveniles.     

Biological features of the common fish species in Olyutorsky-Navarin region and the adjacent waters of the Bering Sea: 1. Gadidae (cods) family

Biological features of the three common fish species, pollock Theragra chalcogramma, Pacific cod Gadus macrocephalus, and saffron cod Eleginus gracilis (Gadidae), have been studied using a 20-year dataset (1995?2015). These species inhabit the northwestern Bering Sea in the summer–autumn period and form the schoolings in Olyutorsky-Navarin region. The size–age parameters, as well as the peculiarities of the body length and body weight dynamics, spawning periods, spawning range, and conditions, of the fish caught by different sampling gear have been analyzed. Due to the construction peculiarities and catch efficiency of the different catching gear, the largest specimens are found in the setlines and snurrevads; the fish caught by the trawls are characterized by the smallest size. The body length and body weight of pollock is greater in the pelagic trawl catches compared to the bottom trawl catches. The abundant brood of Gadidae may well be tracked on the multiyear dynamics graphs reflecting the size distribution, as well as by the decrease of biological parameters of the fish. The studied species inhabit the vast growth areas, so smaller body size of them in the coastal waters may be a result of a high ratio of the young specimens there.     

Biological features of common fish species in Olyutorsky-Navarin region and the adjacent areas of the Bering Sea: 3. Righteye flounders (Pleuronectidae)

Biological features of the seven abundant commercial species—the Pacific halibut Hippoglossus stenolepis, the Greenland halibut Reinhardtius hippoglossoides, the Alaska plaice Pleuronectes quadrituberculatus, the northern rock sole Lepidopsetta polyxystra, the yellowfin sole Limanda aspera, the flathead sole Hippoglossoides elassodon, and the Bering flounder H. robustus (Pleuronectidae)—have been studied for a 20-year period (1995?2015). These species are present in the northwestern Bering Sea in the summer–autumn season; they form the gatherings in Olyutorsky-Navarin region. The size-weight spectra of the fish caught by different fishing gear has been analyzed, the peculiarities of the linear growth and the weight gain, as well as the spawning period and scale and the spawning conditions, have been described. The largest halibut specimens have been registered in the bottom setlines and gill nets, while flounders were in snurrevad catches; the smallest specimens have been observed in trawl catches. The abundant year-class in most of the studied species is seen well on the long-term plots of the fish size spectra and is tracked by the decrease of their biological parameters. The species that demand vast growing grounds (Pacific halibut, Alaska plaice, northern rock sole, and yellowfin sole) are characterized by a smaller average body size of the fish sampled in the coastal waters due to the prevalence of the young specimens in this area.     

Arrow-toothed halibuts Atheresthes spp. (Pleuronectiformes,Pleuronectidae) and their role in the fish community of Olyutorsky-Navarin region and adjacent areas of the Bering Sea

Based on the trawl surveys of 1996–2012, regularities and biological features have been studied in the arrow-toothed halibuts (Atheresthes evermanni and A. stomias) from Olyutorsky-Navarin region and adjacent waters of the Bering Sea. The abundance of the species has increased since 2004. Their remunerative concentrations have been found on the continental slope and shelf. The majority of fish captured during our survey were mature specimens with a length of 37–54 cm and a weight of 0.8–1.4 kg; in the course of our investigation, there was a trend towards a decrease in the average sizes. According to the data obtained in the recent years, if one considers the biomass parameters, arrow-toothed halibuts are among ten dominant species (0.1–0.5% of the total biomass of fish registered in Olyutorsky-Navarin region) and prevail among flatfish (Pleuronectidae). Currently, arrow-toothed flounders are undesirable bycatch in the fishery of Reinhardtius hippoglossoides and Hippoglossus stenolepis.     

Features of the Biology of Mass Fish Species in Russian Waters of the Chukchi Sea. 1. Commercial Fish Biomass. Family Gadidae

Journal of Ichthyology - Based on the results of research in 1995–2020, mass and potentially commercial fish species have been identified in Russian waters of the Chukchi Sea. Among the 72...     

Biological features of the common fish species in Olyutorsky-Navarin region and the adjacent waters of the Bering Sea: 2. Families Macrouridae,Clupeidae, and Osmeridae

Biological features of the four common fish species, giant grenadier Albatrossia pectoralis (Macrouridae), Pacific herring Clupea pallasii (Clupeidae), Pacific rainbow smelt Osmerus mordax dentex, and Pacific capelin Mallotus villosus catervarius (Osmeridae), were studied under the 20-year dataset (1995?2015). These species inhabit the northwestern Bering Sea in the summer–autumn period and form the schoolings in the Olyutorsky-Navarin region. The size–age parameters of the fish caught by different sampling gear, as well as the peculiarities of the body length and body weight dynamics, spawning periods, spawning range, and conditions, were analyzed. The largest specimens of giant grenadier, Pacific herring, and Pacific rainbow smelt were observed in the catches performed by the bottom setline and the gill nets; the smallest fish were found in the trawl catches. The body length and body weight of Pacific herring were larger in the pelagic trawls compared to the bottom trawls; an opposite pattern was observed for the Pacific capelin. The abundant year-class in the species with short life cycle (capelin and herring) is well tracked on the longterm plots of the fish body size; this is accompanied by the decrease of their biological parameters. Herring stock covers large growing grounds; smaller body size was observed for the herring grazing in the coastal waters; young specimens dominate here.     

Ichthyofauna of Russian exclusive economic zone of the Bering Sea: 2. Ecological and zoogeographical characteristics

The ecological and zoogeographical characteristics of 344 species of Pisces and fish-like species comprising the ichthyofauna of the Bering Sea (Russian Exclusive Economic Zone) are presented for the study period of 1995?2012 (original studies) and those for previous findings in this area. The benthic species (elittoral, mesobenthic, and sublittoral; 216 species, or 62.8%) dominate if one takes into account the biotopic characteristics of the species; the majority belongs to the wide-boreal Pacific, wide-boreal Asiatic, and arcticboreal species (255 species, or 74.1%) by the zoogeographic characteristics. The comparative analysis of the fish communities of the western Bering Sea evidences to the significant changes of the ichthyofauna within the depth southwards Navarin Cape. Arctic-boreal species can be considered as a specific faunistic “margin” between the northern and the southern ichthyofauna of the western Bering Sea due to their eurybiont characteristics.     

Fish fauna of the Bering Sea (within Russian waters). Communication 3: Perspectives of commercial fishery

The commercial value of the ichthyofauna of the Bering Sea within Russian waters (Exclusive Economic Zone) is discussed. The ichthyofauna of this region comprises 344 species of fish and fish-like. Most of the species (283 species, or 82.3%) have no commercial value. The rest have commercial value (47 species, or 13.7%) or have the potential commercial value (14 species, 4.1%). Active and large-scale fishery is performed for 27 commercial species both in the open sea and in the coastal areas (mostly by ships); another twenty species are harvested irregularly by local coastal or nearshore fishery.