Southwestern Kamchatka Research Articles

Tanner crab at southwestern Kamchatka: fishing, stock condition and specifics of the assessment

Results of the current stage of research on tanner crab at the southwestern coast of Kamchatka, harvested in the Kamchatka-Kuril fishing subzone are presented. The stock dynamics since 2001 is analyzed, with special attention to its assessing and forecasting. Features of the crab biology associated with terminal molting are described. The algorithm for separation of the tanner crab recruits into morphometrically mature and immature males is developed that allows to calculate probability for a particular size group of morphometrically immature males to undergo the terminal molt and join to the commercial stock. This algorithm is applied for the data collected at southwestern Kamchatka since 2010. Two peaks in total male abundance of tanner crab were observed in 2005–2006 and 2020–2022. Landing of this species was banned in the Kamchatka-Kuril fishing subzone in 2019–2020, as the result of the local population abundance drop in the previous two years, but was resumed in 2021 after its full restoration. Possible reasons for underestimation of the crab recruitment are discussed, related both with features of the species biology and methodological problems. The population in the Kamchatka-Kuril fishing subzone is currently the most abundant for tanner crab, and this stock in 2020–2022 has reached the historical peak. The fishing of tanner crab in the last three years is distinguished by high catches and high rate of the total allowable catch (TAC) utilization.

Features spawning of pollock <I>Gadus chalcogrammus</I> in the northern part of the sea of Okhotsk in the 2010s

A significant amount of data collected during spring complex surveys in the northern part of the Sea of Okhotsk allowed us to characterize pollock spawning in the period 2011–2020. It was found that, on average, during the period under review, caviar accumulations of various densities occupied up to 90% of the surveyed water area. In the spring period caviar on the early stages of development was found on a larger area of the studied landfill, with the exception of some marine stations, where it was absent from catches. At the same time accumulations of caviar on the late stages of development occupied a smaller area, and the densest concentrations indicating the beginning of spawning were noted in the waters off southwestern Kamchatka and above the Swan Hill. In the waters off the West Kamchatka coast 75% of the caviar was located above depths of 50–150 m and only 22% – outside the shelf. A similar distribution of caviar was noted in the North Okhotomorsky district – 76% developed within the shelf and 31% – over the deep-water part of the district. In the Shelikhov Bay the densest concentrations of caviar were located above the deep-water trough during all years of research.

НАХОДКИ ЛАМИНАРИЕВЫХ И ДРУГИХ ВОДОРОСЛЕЙ В УЛОВАХ ДОННЫМ ТРАЛОМ И ЯРУСОМ У ЗАПАДНОГО ПОБЕРЕЖЬЯ КАМЧАТКИ В 2018–2023 гг.

Data are provided on findings of marine macroalgae during bottom trawls and longline fishing on the Western Kamchatka shelf in 2018-2023. During the study period, algae were noted at 65 stations in the depth range from 20 to 350 m. Most of the algae findings were found in the Kamchatka-Kuril fishing subzone, within the South Kamchatka Nature Reserve. Among the macrophytes, representatives of the order Laminariales predominated: Agarum pertusum, A. clathratum, Alaria esculenta, Arthrothamnus bifidus, Eualaria fistulosa, Hedophyllum bongardianum, H. dentigerum, Laminaria yezoensis, Laminaria inclinatoriza and Thalassiophyllum clathrus. For southwestern Kamchatka, only 9 out of 13 species of kelp algae indicated in the literature were discovered. Brown algae Fucus distichus, Desmarestia intermedia, red algae – Ptilota asplenioides, Turnerella mertensiana and lamellar green algae – Ulva fenestrata were found sporadically. A comparative analysis of aerial photography data of coastal areas from Cape Sivuchy to Cape Lopatka in 2002 and modern satellite images did not reveal significant changes in the distribution of littoral and sublittoral algae beds. In the coastal line of capes Sivuchy, Kambalny and Maria that we studied, the kelp belt with an average width of 100-130 m reached in the summer of 2018–2023 the total coverage area is 1.92 km2. The use of accompanying data when conducting bottom surveys of commercial invertebrates and fish, longline cod fisheries, together with the analysis of satellite images, allows for an expert assessment of changes in the species composition and distribution of kelp algae, and is also a promising tool for monitoring the state of macrophyte communities in the Far Eastern seas of Russia.

The Biology and Abundance of Sockeye Salmon Spawners in the Nachikinskoye Lake Basin (Southwestern Kamchatka)

The Biology and Abundance of Sockeye Salmon Spawners in the Nachikinskoye Lake Basin (Southwestern Kamchatka)

О золотоносности мелководной зоны шельфа Юго-Западной Камчатки

The materials, obtained from previous (1972-2019) studies of over 300 km of the coastal land strip in Southwestern Kamchatka and the adjoining underwater slope of the Sea of Okhotsk (in the interfluve of the Bolshaya and the Kikhchik rivers) were analyzed. Gold-rich zones (> 60 mg/m3) in the form of subparallel lenses, oriented along the sea shoreline, were identified between 6.3-30 m isobaths in the shallow marine shelf zone. The gold content of the submarine coastal slope correlated directly with the sediments of the upper coastal zone. Higher gold concentrations (up to hundreds of mg/m3) were detected in Holocene marine sediments of the shallow marine shelf in sampling intervals 0 to 2.0 m. They are mostly confined either to the upper, steepest part of the submarine slope or to the first or second terraced level. These are the areas of the most active impact, near the shorelines (modern and submerged), within which glacial and water-glacial formations are often exposed by erosion. Most of the gold concentrate halos related to ancient shorelines, the western boundary of which lies within 25-30 m isobaths, and to paleovalleys, identified by seismoacoustic profiling. In paleovalleys, flooded by the sea and buried under marine sediments, alluvial placers similar to Tikhangou in Primorsky Krai may be revealed. The most promising within the investigated territory was the area of underwater coastal slope within the Severnaya Mitoga - Utka - Khomutina interfluve, between 5.3-30 m isobaths, where concentrate halos with considerable gold concentrations from 60 to 500-1186 mg/m3 had been revealed.

Sockeye salmon spawners in the basin of Nachikinskoye Lake (south-western Kamchatka): biology and abundance

State of the spawning part of the sockeye salmon population in Lake Nachikinskoye is characterized. Adults of the early race enter the lake from the sea in spring and early summer, mature at a depth and spawn from July to late August in three different loci — creeks, springs and lake, forming the corresponding ecotypes. The late race representatives enter the lake in July-August, mature, and spawn until December in the same loci. The races differ in age structure, size and fecundity. Males dominate in both races, with a growing proportion of small-sized individuals. According to the materials of aero surveys, the number of fish on the spawning grounds decreased gradually until 2016. Recent data are presented for the number of sockeye salmon belonged to early and late races on certain spawning grounds in the lake basin, based on results of quadrocopter surveys in 2018–2021. The number of the early race spawners was ~100–400 × 103 ind., late race ~300–500 × 103 ind.; the fluctuations were not synchronous between the races. These great spawning stocks require reliable protection and detailed annual monitoring to predict further changes.

Пространственная структура приливов у юго-западного побережья Камчатки по данным береговых наблюдений и спутниковой альтиметрии

Based on the known data on the amplitudes and phases of the main tidal waves in coastal areas of southwestern Kamchatka, their alongshore variability was analyzed. It is shown that they increase from south to north. However, it is difficult to accurately assess these variations due to the fact that coastal tide gauges, which were usually installed at the mouths of rivers, are affected by the distorting effect of bottom friction. Satellite altimetry data were used for a more accurate characterization of the spatial variability of tide magnitude. These data were obtained during the passes of the TOPEX/Poseidon satellite in 1992–2002 on the original and 2002–2005 on the orbits shifted by half the inter-track distance. The amplitudes of both diurnal and semidiurnal waves have been revealed to increase sharply in the north direction, and this increase is limited by the shelf zone of southwestern Kamchatka. Significant spatial variations in the tidal wave characteristics are the cause of strong alongshore currents in this area. Estimates obtained on the basis of calculating the difference in the tidal level at the points of various sub-satellite tracks have shown that the speed of the coastal flow can reach 1−1.3 knot. The main contribution to the formation of tidal currents is made by diurnal components.

Investigation of the spawning sockeye salmon in the pool of the Nachikinskoe Lake (South-Western Kamchatka) with the help of a quadcopter in 2018

The Nachikinskoe Lake and its tributaries were first examined in detail with the help of a quadrocopter during running and spawning of early and late sockeye salmon. Quantitative estimates of adult salmon filling in different areas of lake tributaries and its coasts were obtained. The number of spring sockeye salmon was estimated at ~30 thous. specs, and late — at ~145 thous. specs (summation of adults counted every ~2 weeks) and 140 thous. specs (127–153 thous. specs), by means of imitation model. According to the photos from the quadrocopter, the boundaries of the spawning grounds of the late sockeye salmon in 2018 are marked on the space picture. The area of spawning grounds is calculated — 307 thous. m2. The maximum density of distribution of adult salmon exceeded 0.64 specs/m2, the density of spawning was 4.5 specs/m2.

ЛАМИНАРИЕВЫЕ ВОДОРОСЛИ ЗАПАДНОЙ КАМЧАТКИ

Western Kamchatka is still poorly studied in floristic and fishing aspects and there is no accurate understand-ing on the boundaries of different kelp species distribution in the area. During the 2020 field study in the coastal area located from Cape Ambon to the mouth of Utholok river, including the area proximate to Ptichiy Island, we found 5 kelp species, including Phyllariella ochotensis, Pseudolessonia laminarioides, Laminaria inclinatorhiza, Saccharina latissima, and Alaria esculenta sensu lato. The first 3 species are endemic to the mainland coast of the Sea of Okhotsk. A special search off the coast of southwestern Kamchatka for another Okhotsk endemic species, Laminaria appressirhiza, showed that it was absent. A representative of the Ber-ing Sea kelp flora Hedophyllum bongardianum does not occur on western Kamchatka north of 51°N. The morphometric characteristics of plants belonging to different age groups and morphological features typical for Western Kamchatka’s populations of these species are discussed. Additionally, the molecular phylogeny of L. appressirhiza and H. bongardianum collected from the Sea of Okhotsk are discussed. As shown, the first species belongs to the genus Laminaria. From a commercial point of view, this coastal area was estimated as unpromising for the organization of kelp collection by a traditional manual method.

CURRENT STATE OF STOCK FOR TANNER CRAB CHIONOECETES BAIRDI RATHBUN, 1924 (CRUSTACEA, DECAPODA) AT THE SOUTH-EASTERN COAST OF KAMCHATKA

Tanner crab Chionoecetes bairdi is the highly valuable object of commercial fishery dwelling in the seas surrounding Kamchatka Peninsula. Its landings started at the southeastern coast of Kamchatka in early 1980s and continued till 2009, when the fishery was stopped by reasons independent on the stock state. It was launched again in 2017. Now the species is landed mostly in the Petropavlovskaya fishery subzone (62 % of the total allowable catch of tanner crab in Russia in 2019), whereas its stocks at southwestern Kamchatka and in the northwestern Bering Sea are rather low. Modern condition of the tanner crab population and its distribution at southeastern Kamchatka are considered on the data of the trap surveys conducted in spring and summer of 2012 and 2018. Between these years, commercial males of these species spread wider at southeastern Kamchatka and formed commercial aggregations in the northern Avachinsky Bay and in the southern and central parts of the Kronotsky Bay, but were rare southward from Cape Povorotny. They became larger: while size of the males varied in the range 50–170 mm in both years, the males with the carapace width < 120 mm prevailed in 2012, but the large-sized males with commercial size were more numerous in 2018. Percentage of the females in the catches was low both in 2012 and 2018 that is typical for the trap catches. The crabs at the 3rd stage of molting dominated both in May and August of 2012 and 2018. Injury level of the commercial males was rather high and increased from 2012 to 2018 in 8 %. Good current condition of the tanner crab population at southeastern Kamchatka is concluded.

NEAR-VESSEL SEABIRD AGGREGATIONS IN THE WINTER TRAWL FISHERY OF POLLOCK IN THE OKHOTSK SEA

At least 12 seabird species aggregated permanently around the vessels of pollock trawl fishery in the Okhotsk Sea in January-April, 2015. They were attracted by the fish processing waste and small-sized fish falling from trawls. Fulmars dominated in all fishery districts except the East-Sakhalin subzone (their number was 68.9 % of all birds, on average), they were the most abundant at southwestern Kamchatka. The secondary abundant group of species was large-sized white-headed gulls of Larus genus (31.0 %), mostly slaty-backed gull. Species composition of aggregations and number of the birds were quite dynamic in space and time, but the largest and the most diverse aggregations were observed in the Kamchatka-Kuril fishery district where many seabirds wintered in the Pacific waters. The largest aggregation in this subzone had up to 23,000 ind. around one separate vessel, so hundreds of thousands birds may gather in the area of a trawling fleet operation. Size and species composition of the near-vessel aggregations are determined by biotopic preferences of the species and weather conditions. The pollock trawl fishery is regarded as a powerful factor of the seabirds habitat in the Okhotsk Sea, and the catching and processing waste is a reliable food base for huge bird community, particularly important in winter season.

Genetic variability and population structure of sockeye salmon from the Asian Coast of Pacific Ocean

Variability of six microsatellite loci and 45 single nucleotide polymorphism (SNP) loci was analyzed in 17 samples of sockeye salmon from 10 major spawning watersheds on the Asian coast of the Pacific Ocean. On the basis of the analysis of SNP loci variability of sockeye salmon in the examined part of the range, five population groups were identified, including local stocks from the Palana, Okhota, and Kamchatka rivers, as well as the population groups of Southwestern Kamchatka, and Northeastern Kamchatka and Chukotka. Rather different pattern of samples differentiation was obtained by estimating variability of six microsatellite DNA loci. Regional complexes of the eastern and western coasts of Kamchatka were identified. Moreover, sockeye salmon from the Palana River fell into the cluster of Western Kamchatka populations, while the population from the Okhota River and Meynypilgin lake–river system (Chukotka), confined to the subperiphery of the range, where the most differentiated from the others. The possible reasons for the discrepancies and high divergence of the Palana River and the Okhota River sockeye salmon populations, inferred from the SNP markers analysis, are discussed.

Middle Eocene diatoms from the Pervoocherednaya hole, eastern Sea of Okhotsk

The results of the study on diatoms revealed in Eocene deposits of the Cenozoic sequence of the Pervoocherednaya hole, which was drilled near the Southwestern Kamchatka coast, are presented. The taxonomic composition of the studied diatom assemblage including marine diatom plankton is characterized. These are the first findings of Middle Eocene planktonic diatoms having a stratigraphic value in sequences of the eastern Sea of Okhotsk region.

Eocene accretion at Kamchatka and a pulse of mantle plume magmatism

The paper presents newly obtained chemical analyses of metamorphosed mafic volcanic rocks from the upper reaches of the Krutogorova River, southwestern Kamchatka. According to their geochemistry, these mafic rocks and the orebearing mafic rocks of th e cortlandite-gabbro-norite association at the Kuval� orog occurrence of Ni mineralization in Kamchatka were produced by melting undepleted mantle at its adi� abatic decompression (without involvement of subductionrelated fluids and melts). The significant crystal� lization depths of the small cortlandite-gabbro-norite intrusions are confirmed by our pressure evaluations ( P = 8 kbar) by a newly developed amphibole barometer; the crystallization depths of the small subvolcanic intrusions was much shallower. The physical mechanism of derivation of the primitive partial mantle melts is discussed using simple numerical simulations of processes related to the onset of subduction and oceanic slab breakoff. Geochemical data and results of our numeri cal simulations testify that the picrobasaltic magmas were generated in ascending flows induced in the upper mantle by complicated geodynamic processes during the accretion of the Achaivaam-Valaginskii island arc to the Eurasian continent in the Eocene.

Downstream migration, behavior, and distribution of fish fry in the lower reaches of the Ozernaya river (Southwestern Kamchatka)

Fry of five species of salmonids are found in the lower reaches of the Ozernaya River. The most abundant are chum salmon and pink salmon which compose the bulk of fry which migrate downstream from the river to the sea. The dates and duration of migration of particular species differed according to the specific traits of their biology. Pink salmon is characterized by a simple migration strategy: it migrated downstream in a short time after emergence from theground. Chum salmon has two strategies of downstream migration: some fry start migration soon after emergence, and others remained in the river for several weeks. Downstream migration of pink salmon occurred mainly at night in contrast to that of chum salmon, over 24 h, the part of daytime increased with growth, of the fish. Migration of pink salmon was passive. Passive migration of chum salmon changed into active-passive with growth of the fish. The ratio of fish in the inshore zone and in the current was different in the course of 24 h. The number of fish in the inshore zone decreased in the period of intensive downstream migration.

Intra- and interpopulation variability of southwestern Kamchatka sockeye salmon Oncorhynchus nerka inferred from the data on single nucleotide polymorphism

The variability of 45 single nucleotide polymorphism (SNP) loci was studied in nine samples of the sockeye salmon Oncorhynchus nerka from the rivers of southwestern Kamchatka. The Wahlund effect, gametic disequilibrium at some loci, and a decrease in interpopulation genetic diversity estimates observed in samples from the Bolshaya River outlet are explained in terms of the samples' heterogeneity. Partitioning of mixed samples using some biological characteristics of the individuals led to a noticeable decrease in the frequency of these phenomena. It was demonstrated that the allelic diversity between the populations within the river Plotnikovs accounted for the larger part of genetic variation, as compared to the differentiation between the basins. The SNP loci responsible for intra- and interpopulation differentiation of sockeye salmon from the rivers of southwestern Kamchatka were identified. Some recommendations for field population genetic studies of Asian sockeye salmon were formulated.

Floodplain succession and soil nitrogen accumulation on a salmon river in southwestern Kamchatka

We documented riparian primary succession on an expansive floodplain (Kol River, Kamchatka, Russian Federation) that receives large nitrogen subsidies from spawning Pacific salmon. As is typical of primary succession, new alluvial deposits in the lower Kol floodplain were nitrogen poor (200 kg persulfate N/ha to 10 cm soil depth); however, nitrogen accumulated rapidly, and soils contained 1600 kg N/ha (to 10 cm + the litter layer) by 20 years. Soil nitrogen approached an asymptote at ∼2500 kg N/ha by 80 years. Nitrogen-fixing Alnus trees were a minor component of the forest community during the first 20 years of succession. However, salmon carcasses were a substantial nitrogen source during this period of rapid nitrogen accumulation. Similar to other northern Pacific Rim floodplains, we found that new alluvial deposits were colonized by Salix, Chosenia, and Alnus trees; but, unlike other described chronosequences, the community transitioned into meadows of tall forbs (some >2.5 m in height) dominated by F...

Variations of the oxygen minimum zone of the Okhotsk Sea during the last 50 ka as indicated by benthic foraminiferal and biogeochemical data

Benthic foraminiferal and sediment biogeochemical data (total organic carbon, calcium carbonate and biogenic opal contents) in two cores (1265 and 1312 m water depths) from the southeastern Sakhalin slope and one core (839 m water depth) from the southwestern Kamchatka slope were investigated to reconstruct variations of the oxygen minimum zone during the last 50 ka in the Okhotsk Sea. The oxygen minimum zone was less pronounced during cooling in the MIS 2 that is suggested to be caused by a maximal expansion of sea ice cover, decrease of marine productivity and increase of production of the oxygenated Okhotsk Sea Intermediate Water (OSIW). A two-step-like strengthening of oxygen minimum zone during the warmings in the Termination 1a and 1b was linked to (1) enhanced oxygen consumption due to degradation of large amount of organic matter in the water column and bottom sediments, originated from increased marine productivity and supply of terrigenous material from the submerged northern shelves; (2) sea ice cover retreat and reduction of OSIW production; (3) freely inflow of the oxygen-depleted intermediate water mass from the North Pacific.

Living benthic foraminifera of the Okhotsk Sea: Faunal composition, standing stocks and microhabitats

Live (Rose Bengal stained) benthic foraminifera were investigated in surface sediment samples from the Okhotsk Sea to reveal the relationship between faunal characteristics and environmental parameters. Live benthic foraminifera were quantified in the size fraction > 125 µm in the upper 8 cm of replicate sediment cores, recovered with a multicorer at five stations along the Sakhalin margin, and at three stations on the southwestern Kamchatka slope. The stations are from water depths between 625 to 1752 m, located close or within the present Okhotsk Sea oxygen minimum zone, with oxygen levels between 0.3 and 1.5 ml l - 1 . At the high-productivity and ice-free Kamchatka stations, live benthic foraminifera are characterized by maximal standing stocks (about 1700-3700 individuals per 50 cm 2), strong dominance of calcareous species (up to 87-91% of total live faunas), and maximal habitat depths (down to 5.2-6.7 cm depth). Vertical distributions of total faunal abundances exhibit a clear subsurface maximum in sediments. At the Sakhalin stations, which are seasonally ice-covered and less productive, live benthic foraminifera show lower standing stocks (about 200-1100 individuals per 50 cm 2), lower abundance of calcareous species (10-64% of total live faunas), and shallower habitat depths (down to 2.5-5.4 cm depth). Faunal vertical distributions are characterized by maximum in the uppermost surface sediments. It is suggested that 1) lower and strongly seasonal organic matter flux, caused by the seasonal sea ice cover and seasonal upwelling, 2) lower bottom water oxygenation (0.3-1.1 ml l - 1 ), and 3) more pronounced influence of carbonate undersaturated bottom water along the Sakhalin margin are the main factors responsible for the observed faunal differences. According to species downcore distributions and average living depths, common calcareous species were identified as preferentially shallow, intermediate and deep infaunal. Foraminiferal microhabitat occupation correlates with the organic matter flux and the depth of the oxygenated layer in sediments.

Seasonal and interannual variations of sockeye salmon (Oncorhynchus nerka) microsatellite DNA in two Kamchatka lake-river systems

Seasonal and interannual variations in the sockeye salmon populations from two lake-river systems of the East and West Kamchatka were studied. Stability of allele and genotypic frequencies of six microsatellite DNA loci in the adjacent generations and spawning populations of the sockeye salmon of the Bol'shaya River was confirmed experimentally. The pairwise intersample differentiation (F(st)) of the local sockeye salmon populations from the southwestern Kamchatka coast (Ozernaya and Bol'shaya Rivers)was almost 7 times higher than the corresponding values for the spawning populations of the Bol'shaya River sockeye salmon of the adjacent years; 15 times, for the adjacent Bol'shaya River sockeye salmon generations; and four times, for the seasonal races within the Kamchatka River.