On the origin of endemic stone charr in the Kamchatka River basin

Hydrobiologia - The Kamchatka River basin (Kamchatka Peninsula, Russia) is populated by numerous anadromous and resident forms of charr, Salvelinus, including the endemic stone charr, a specialized...     

The Relationships of the Charrs Salvelinus sp. 4 (Salmoniformes: Salmonidae) from Lake Nachikinskoe,Kamchatka, as Inferred from Complete Mitochondrial Genome Analysis

Russian Journal of Marine Biology - We have performed a comparative analysis of complete mitochondrial genomes variability of the endemic charr Salvelinus sp. 4 from Lake Nachikinskoe (Kamchatka,...     

Specific features of distribution,ecology, and dynamics of catches of blotched snailfish Crystallichthys mirabilis (Liparidae) in Pacific waters off the northern Kuril Islands and southeastern Kamchatka

Based on materials of 1992–2002, data on the spatial-bathymetric distribution and size-age composition of blotched snailfish Crystallichthys mirabilis and species accompanying it in catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are presented. This relatively large representative of the family Liparidae (maximum length in catches 50 cm, body weight 2150 g) is found throughout the examined area in the depth interval of 76–755 m at near-bottom temperature of ?1.2 to +4.2°C. Maximum catches (over 200–500 individuals or 180–280 kg per hour trawling) year round are recorded off the southeastern extremity of Kamchatka, from the oceanic side of the Shumshu and Paramushir islands and on the beam of the Fourth Kuril Strait in the bathymetric range of 151–350 m. The magnitude of its catches in the examined area is subjected to interannual, seasonal, and diurnal dynamics.     

Specific features of distribution, some features of biology, and the dynamics of catches of smooth lumpsucker Aptocyclus ventricosus (Cyclopteridae) in waters of the Pacific Ocean off the Kuril Islands and Kamchatka

On the basis of data on bottom trawl catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka (1992–2002), quantitative indices of occurrence of the smooth lumpsucker Aptocyclus ventricosus and the range of preferred habitation temperature are provided. Its spatial and vertical distribution are analyzed, and specific features of size composition and the relationship between the length and weight of the body and between the average weight and the capture depth are considered; the diurnal, seasonal, and long-term dynamics of occurrence and of the amount of average catches is presented; data on the species composition of fish present in catches parallel to A. ventricosus are cited.     

Specific features and dynamics of catches of twoline eelpout Bothrocara brunneum (Zoarcidae) in pacific waters near Kuril Islands and Kamchatka

We provide data on the occurrence, spatial-bathymetric distribution, and size composition of twoline eelpout Bothrocara brunneum and species accompanying it in catches in Pacific waters of the northern Kuril Islands and southeastern Kamchatka. This comparatively numerous and relatively large representative of the fam. Zoarcidae (maximum length of 74 cm, body weight 2.98 kg) in the study period (1992?C2002) was found everywhere at depths 198 to 824 m at the near-bottom temperatures of 0.5?C4.2°C. However, its maximum by density concentrations with catches to 150?C160 kg per hour of trawling were constantly recorded on the beam of the Fourth Kuril Strait and at a site southward of it in two ranges of depths-400?C600 and 700?C800 m at near-bottom values of temperature 2.1?C3.0°C. The ratio between the depth of catches and sizes of the twoline eelpout was analyzed. It was shown that the amount of its catches in Pacific waters of the northern Kuril Islands and southeastern Kamchatka is subject to some interannual, seasonal, and diurnal dynamics.     

Arctic charr in Lake Myvatn: The centennial catch record in the light of recent stock estimates

In Lake Myvatn, Arctic charr (Salvelinus alpinus) is economically the most important fish species. It is fast growing fish and its size at maturity is 35–50 cm at the age of 4 to 5 years. Catch statistics that are available for the whole 20th century show considerable long-term variation with the highest catch in the 1920s. The catches after 1970 are about 40% lower than the average from 1930–1969 and the annual catches for the last decade are the lowest. Stock size during the winter fishing season fluctuated considerably between years, with average annual fishing mortality of 83.9%. The Arctic charr population has been monitored annually since 1986, using standard series of gill nets of different mesh sizes. In 1988 one to three-year-old fish were heavily reduced in numbers during the summer months. There are indications of a similar event in 1997. In both years the charr changed its main diet from Cladocera and chironomid midges to three-spined sticklebacks Gasterosteus aculeatus and snails. At the same time its condition deteriorated. The catch in the monitoring fishery in Lake Myvatn correlates with the stock size in the beginning of the following winter fishing season deduced from Leslie's method and can give prospects for the fishery in the successive fishing season. An index of abundance of young charr also correlates with the number of chironomids and cladocerans and also with ducklings that feed on the same food as the charr. Large fluctuations in the Arctic charr population in Lake Myvatn seem to be related to changes in the main food species. The catch records available from Lake Myvatn can to a large extent be used as a measure of changes of the Arctic charr population in the lake for the past century.     

Specific features of distribution and ecology of two species of sea poachers of genus Podothecus (Agonidae) in pacific waters off the northern Kuril Islands and southeastern Kamchatka

According to materials of studies in 1992–2002, data on occurrence, spatial-bathymetric distribution, and size-weight composition of two species of sea poachers of the genus Podothecus (P. accipenserinus and P. sturioides) and species accompanying them in catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are provided. The distribution of these relatively large representatives of the family Agonidae (maximum length of the first species is 38 and that of the second species is 33 cm, body weight of both 200 g) noticeably differ. In the period of observations, P. accipenserinus was found in catches only to the north of the Fourth Kuril Strait at depths of 80–570 m at near-bottom temperature of ?0.70 to +4.25°C, while P. sturioides was found over the entire studied area in a wider bathymetric range (85–786 m) exclusively at positive values of near-bottom water temperature (0.10–3.55°C). However, more frequently and in greater amounts, both species of sea poachers were recorded in catches off the southeastern extremity of Kamchatka and from the oceanic side of the Shumshu and Paramushir islands. The relationship between the depth of catch and sizes of P. accipenserinus and P. sturioides was analyzed. It is shown that their occurrence and the magnitude of catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are subjected to some interannual, seasonal, and diurnal dynamics.     

Specific features of distribution and ecology of sawback poacher Sarritor frenatus (Agonidae) in Pacific Waters of the Northern Kuril Islands and Southeast Kamchatka

According to materials of 1992–2002, data on the occurrence, spatial-bathymetric distribution, and size-weight composition of sawback poacher Sarritor frenatus and species accompanying it in catches in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are provided. This comparatively numerous and relatively small representative of the family Agonidae (maximum length 31 cm, body weight 103 g) in the period of studies was found uniformly at depths of 78-790 m at near-bottom temperature of ?1.2 to ?4.2°C. In spring, summer, and winter months, maximum catches (over 500–1000 ind./h of trawling) were recorded in the southernmost and northernmost sites of the study area in a bathymetric range of 101–500 m; increased concentrations of this poacher were recorded also on the beam of the Fourth Kuril Strait near the southeastern extremity of Paramushir Island only in the autumn period. The ratio between the depth of catch and the sizes of sawback poacher is analyzed, and the data on the composition of its food in waters of the northern Kuril Islands is given. It is shown that the occurrence and amount of catches of this poacher in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are subjected to some interannual, seasonal, and diurnal dynamics.     

The growth history of anadromous white-spotted charr in northern Japan: a comparison between river and sea life

Anadromous white-spotted charr Salvelinus leucomaenis in a natural river in northern Japan migrated to the sea mainly at age 3+ years. Sea-run charr grew faster than parr, particularly as first time migrants. Sea-run charr repeated seaward migration up to three times; the observed maximum age was 5+ years old. The likelihood ratio test identified significant differences in asymptotic size and individual growth variability between parr and sea-run charr. Sea-run charr had an asymptotic size ( L ^∞) twice as large as parr, while the growth parameter ( K ) was similar between sea-run and parr. Growth variability was higher for parr than for sea-run charr.     

Specific features of distribution and ecology of two species of armorhead sculpins of the genus Gymnocanthus (Cottidae) in Pacific waters of the northern Kuril Islands and Southeastern Kamchatka

Based on materials of 1992?C2012, data on the occurrence, spatial-bathymetric distribution, and size-weight composition of armorhead sculpin Gymnocanthus galeatus and purplegray sculpin G. detrisus and species accompanying them in catches in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are provided. These comparatively numerous, medium-sized representatives of the family Cottidae (maximal length of the former species 49 cm, weight 1400 g and that of the latter, 48 cm and 1140 g) in the period of study occurred uniformly at depths of 76 to 596 m at a near-bottom temperatures of ?1.2 to + 4.5°C. Their maximum by density concentrations were constantly recorded at the beam of the Fourth Kuril Strait, from the oceanic side of the Paramushir and Shumshu Islands, and off the southeastern extremity of Kamchatka mainly in the lower part of the shelf (depths of 80?C200 m) at temperatures of ?1.0 to +2.5°C. Regularities of spatial-bathymetric distribution of different size groups of these species were analyzed. It was shown that the occurrence and the size of catches of both armorhead sculpins in Pacific waters of the northern Kuril Islands and southeastern Kamchatka are subjected to some inrterannual, seasonal, and diurnal dynamics.     

Evidence for divergence between sympatric stone charr and Dolly Varden along unique environmental gradients in Kamchatka

Here, we describe the biological and ecological differences between partially anadromous Dolly Varden and riverine stone charr distributed in the Kamchatka River middle course. Endemic stone charr, being the ambush predator, is defined by the accelerated growth and prolonged lifespan, robust body, and large mouth, as well as specific marble coloration since an early age. The significant restriction in gene flow between the stone charr and benthos-eating Dolly Varden was supported by an allelic distribution of eight microsatellite loci. Herewith, the identity of mitochondrial DNA control region and intron sequences of growth hormone and metallothionein genes confirms a relatively recent diversification of the groups within the single basin. We suggest the key role of the specific environment for reproduction isolation of stone charr. It occupies coniferous taiga zone with dark-colored water, whereas Dolly Varden spawns uppercourse in the zone of stunted, windblown forest. Conifer litter decomposition products could drive natural selection of stone charr via metabolism acceleration and resistance to toxicants. The metabolic difference could promote piscivory and development of the specific morphological peculiarities of the stone charr. Therefore, we present the first evidence in favor of trophic-based sympatric diversification in a river basin at high latitudes.     

The cultural importance and international recognition of the Arctic charr Salvelinus alpinus populations of Windermere,UK

The Arctic charr Salvelinus alpinus populations of Windermere, England’s largest natural lake in the Lake District of north-west England, have been studied since the 1940s. However, the species’ cultural importance has a much longer history and these populations have been fished since 1223. As early as 1660, Arctic charr were exploited in a high-profile commercial net fishery and greatly enjoyed by locals and in a ‘potted’ form by wealthier members of UK society. However, overfishing led to substantially decreased catches and commercial netting was stopped in 1921. Local fishing for Arctic charr persists to the present as a small recreational plumb-line fishery using artificial lures. These fishing activities and resulting catches have long held great cultural interest for the local community and visiting national and international tourists. The cultural importance of the Arctic charr populations of Windermere has recently been the subject of national media interest that culminated in a 2017 documentary film highlighting environmental issues facing the Arctic charr and also celebrating the role of this iconic species in the cultural life of Windermere. In addition, international recognition of the Arctic charr populations of Windermere also contributed to the Lake District becoming a UNESCO World Heritage Site in 2017.

     

Influence of spring and summer water temperature on brook charr, Salvelinus fontinalis, growth and age structure in the Ford River, Michigan

Synopsis The influence of late spring and summer water temperatures on brook charr, Salvelinus fontinalis, growth and age structure was evaluated from 1984 to 1991 in the Ford River, Michigan. Temperature was monitored and brook charr sampled for vital statistics from late May through September using fyke nets and weirs at four locations within a 25.8 km section of stream. Scale analysis was used to determine captured brook charr age, past length at age and relative annual growth rates. Late spring and summer water temperature patterns varied between years with the greatest variability occurring in May and June. Age and size structure also varied between years and was significantly related to temperature. Years with cooler late spring and summer temperature patterns were dominated by older (age 2 and 3), larger brook charr, while years with warmer spring and summer temperature patterns were dominated by younger (age 1), smaller brook charr. Spring and summer temperature did not appear to have a significant effect on the growth of age 0 or age 1 brook charr. However, temperature was negatively related to brook charr growth from age 2 on. As spring and summer water temperatures are critical to brook charr growth and survival, it is important that a streams thermal regime be considered when establishing management goals for this species.     

Habitat use and life history of brown trout (Salmo trutta) and Arctic charr (Salvelinus alpinus) in some low acidity lakes in central Norway

Habitat utilization and the life history of browntrout Salmo trutta and Arctic charr Salvelinus alpinus were investigated in fivesympatric populations and five allopatric brown troutpopulations in Høylandet catchment, a atmosphaericlow deposition area in Mid Norway. There was asignificant inverse correlation in abundance ofepibenthic Arctic charr and brown trout in theselakes, indicating that the latter species is dominant.The largest numbers of sympatric brown trout andArctic charr were caught in epibenthic habitat. In twolakes, brown trout to some extent also occurredpelagically, while pelagic individuals of Arctic charrwere found in all five lakes. The main food items forboth epibenthic and pelagic brown trout wereterrestrial surface insects and chironomid pupae.Zooplankton was the primary food item for Arctic charrin both habitats. Although the age distribution wasvery different in the populations, neither speciesseem to suffer from recruitment failure. There was nosignificant difference in survival rates betweensympatric populations of brown trout and Arctic charr.We found a significant inverse correlation betweenepibenthic catches of brown trout and the mean weightof 4+ fish, the most abundant age group. However, ifusing weight data for three-year-old fish, no suchrelationship was found for Arctic charr. Brown troutand Arctic charr reached asymptotic lengths of197–364 mm and 259–321 mm, respectively. Both speciestypically reached sexual maturity at age 2–3, and nomaturation-induced mortality was evident. We concludethat fish populations in Høylandet lakes areregulated throughout their lifes by inter- andintraspecific competition.     

Spatial distribution,size composition,and dynamics of catches of the Okhotsk skate <Emphasis Type="Italic">Bathyraja violacea</Emphasis> in the North Pacific Ocean

The results of the long-term (1963–2015) studies of spatial and vertical distributions, dynamics of abundance and size composition of the Okhotsk skate Bathyraja violacea in the North Pacific Ocean are presented. This species is the most abundant at depths of 100–400 m; in the cold season, it migrates to the larger depths for wintering, while it migrates to shallower depths in the warm season. Specimens of the length 12 to 132 cm with prevalence of skates of 50 to 80 cm long were recorded in catches. The difference between males and females in body weight and length was not considerable. Condition factor of specimens decreases from January to August and begins to increase in September. Males dominate among the skates up to 30 cm long, females dominate in the size groups of 30–60 cm and >70 cm, while an almost equal sex ratio is observed in the size group of 60–70 cm. The dynamics of the catches of the Okhotsk skate vary in different regions: in the western Bering Sea and in the Sea of Okhotsk, the catches consistently increased during the study period, the catches increased to the mid-1980s–early 1990s in the Kuril and Kamchatka waters of the Pacific Ocean, and then a decrease has been observed; in the eastern Bering Sea, the peak of catches occurred in the mid-1970s, and then they decreased subsequently.     

Age and growth of the Pacific halibut <Emphasis Type="Italic">Hippoglossus stenolepis</Emphasis> and the size-age composition of its catches in the North-Western part of the Pacific Ocean

The results of investigation are discussed on age and growth of the Pacific halibut Hippolglossus stenolepis, as well as size-age composition of its catches in three regions of the North-Western Pacific—in Navarin area of the Bering Sea, in Pacific waters on the Northern Kurils and south-eastern Kamchatka, of the Southern Kurils—from the end of the last century. The growth rate of Pacific halibut is similar in all three regions in spite of their considerable geographic remoteness. No significant differences in the growth rate of males and females in these regions, as well as no significant interannual differences in growth of specimens caught in Pacific waters off the Northern Kurils and south-eastern Kamchatka in 1996–2000, are found. Comparison of the present-day size-age composition and that in the beginning-middle of the last century revealed their considerable similarity.     

Environmental influences on an exploited anadromous Arctic charr stock in Labrador

Arctic charr Salvelinus alpinus at Nain, Labrador, were influenced by recent variability in measured environmental variables and able to mitigate partially the effects of past conditions in a single year. Weather conditions prevailing during the first winter and sea migration life-stages also exerted significant influence on measured age and weight characteristics and are argued to play a role in determining the population dynamics of exploited stocks.     

Specific features of distribution and ecology of the Japanese dog poacher <Emphasis Type="Italic">Percis japonica</Emphasis> (Agonidae) in Pacific waters off the northern Kuril Islands and southeastern Kamchatka

According to materials of 1992–2002, data on the spatial-bathymetric distribution and size composition of the Japanese dog poacher Percis japonica in Pacific waters off the northern Kuril Islands and southeastern Kamchatka are provided. This comparatively scarce, medium-sized representative of the family Agonidae (maximum length of 46 cm) in the observation period was found in the lower part of the shelf and the upper bathyal over the entire study area from 47°50′ to 52°00′ N at depths of 76–770 m; however, its maximum catches (more than 200 individuals per hour of trawling) were constantly recorded in the spring and autumn months at the traverse of the Fourth Kuril Strait and at the eastern slope of the seamount of the northern link of the external Kuril Ridge, mainly in the range of 251–350 m at a temperature of 1.6–3.0°C. The relationship between the depth of catch and the average weight of P. japonica was analyzed. It was shown that the value of its catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka is subjected to some interannual, seasonal, and diurnal dynamics.     

Comparative characteristic of sablefish Anoplopoma fimbria in catches with passive and active fishing gear in the northwestern Pacific ocean

According to materials of trap, long-line, and trawl fishing, specific features of distribution of sablefish Anoplopoma fimbria and some of its biological characteristics in Pacific waters off the southeastern coast of Kamchatka, continental slope of the western part of the Bering Sea, Shirshov Underwater Ridge, and off the Commander Islands are considered. Maximum density concentrations according to data of trap fishing was noted along southeastern coast of Kamchatka and the data of trawl fishing indicated most frequent catches in the western part of the Bering Sea in the area of Koryak coast up to Cape Navarin. The pattern of vertical distribution in different areas considerably differs. The magnitude of trap catches in different areas is different and determined by the type of trap and the period of soaking. The size composition, fatness, and the sex ratio are different in catches of different fishing gear and differ between regions. On the whole, in Russian Far Eastern waters, females mature in mass at a body length of 71 cm and males at 57 cm.     

Monthly variability of hydroacoustic fish stock estimates in a deep lake and its correlation to gillnet catches

Monthly (April to November) hydroacoustic surveys and parallel gillnet catches were used to determine vendace Coregonus albula abundance, biomass and population dynamics in a deep oligotrophic lake. By hydroacoustic surveys, recruitment of 0+ year vendace could clearly be detected. In contrast, gillnet catches resulted in low numbers of 0+ year fish, and similarly under-represented proportions of the oldest vendace. Consequently, the correlation between hydroacoustics and gillnets with respect to fish numbers and geometric mean fish total length was high only for the age groups 1 + to 4+ years. Annual variability in hydroacoustic estimates offish abundance and biomass was high (CV=26–29%) which reflects the seasonal population dynamics of vendace.