BIOLOGICAL RESOURCES
Data on traumatization of sockeye salmon Oncorhynchus nerka spawners in the Meynypil’gyn lake-river system by lampreys are presented on results of observations in 1998– 2018. Features and localization of injuries are described comparing the injuries of males and females and biological parameters of fish with and without the injuries. In the Meynypil’gyn lake-river system, relative to other areas of Russian Far East, the portion of fish with injuries from lampreys is medium for sockeye salmon, and low for pink salmon Oncorhynchus gorbuscha and charr Salvеlinus malma. Judging by size of the wounds, the injuries were caused mostly by arctic lamprey Entosphenus tridentatus. Generally, about 68 % of sockeye spawners were attacked by lampreys during their pre-spawning migrations just before entering the fresh waters, but the percentage (P) depends on length (L) of fish: P = 1.2026 . L + 1.2192 (R2 = 0.879). So, the portion of injured fish increased from 2.7 % for the sockeye producers with length < 500 mm to 31.2 % for those with length 671–680 mm. Mean size and weight of the male and female sockeye spawners with traces of lampreys were statistically significantly higher than these parameters for the fish without injuries. The males injured by lampreys were larger than the males without injures in 18 mm and 295 g, the females — in 5 mm and 80 g, on average. Sockeye females had weaker and less numerous damages, so their portion among the fish with 1 injury was 45.4 %, among the fish with 2 injuries — 42.9 %, among the fish with 3 or more injures — 37.0 %. Besides, mean size of the injured sockeye increased with a number of injures and for the groups with 1, 2, and 3 or more injures it was for females: 604, 608, and 613 mm, for males: 655, 667, and 674 mm, respectively. Such dependencies of alive fish traumatization on their size are caused by higher mortality of small fish after lampreys attacks. There is concluded that arctic lamprey affects significantly on sexual and size composition of sockeye spawners in the Meynypil’gyn lake-river system providing selection of fish with larger size and weight, in particular males.
Results of long-term studies of pink salmon reproduction (spawners run to the rivers, fry downstream migration and adults returns, their survival during the freshwater and marine periods) are widely presented for southern Sakhalin and southern Kuril Islands but were not published until nowadays for northern Sakhalin because of many uncertainties in the data. New series of scientific articles published by A.A. Zhivoglyadov with co-authors pretends to fill this gap, but they content a lot of errors and inaccuracies, so both presented data and conclusions should be considered very carefully.
Results of commercial exploitation of the yesso scallop resources in the Sakhalin-Kuril region in 2000–2011 are analyzed, taking into account the data of diving surveys at the depth of 2–30 m (on average 5 stations with sampling from 50 m2 per transect) in the 2009–2012. The results are compared with published and archived data for unexploited period. Range of the scallop spatial distribution did not changed. Size of the scallop increased, but its abundance and biomass decreased, in general, in particular in the Aniva Bay and on the shoal at southern Kuril Islands, though the scallop became more abundant in the Aleksandrovsky Bay and Patience Bay. The stocks reducing in the Aniva Bay was possibly caused by lack of feeding.
During spring-summer flood (in June-July). transit underyearling of coho salmon, having or having no scales, migrate to Lake Kursin at the lower Kamchatka River, where resident coho salmon never spawn. In this case, additional zones of closely-spaced sclerites (ZCS) can be formed on their scale because of feeding change (additional ZCS of the 1st type). Seasonal growth restarts and annual zones of close sclerites (annual ring) form in middle May — early June on scales of yearlings and elder coho salmon wintered in Lake Kursin. These results contradict to the earlier conclusion of G.V. Bazarkin (2003) that the coho yearlings have no additional ZCSs in Lake Kursin, though the same collection of scale was analyzed. In late July — August, other additional ZCS can be formed on the scale of coho yearlings in the lake (additional ZCS of the 2nd type) that is next after the well-differentiated first annual ring. Possibly, the additional ZCSs were omitted by G.V. Bazarkin because of the scale measuring with high magnification — 113 times, without preliminary evaluation with lower magnification — 35–50 times, when the boundaries of certain or uncertain ZCSs are visible better. Rate of the sclerites forming was examined for coho juveniles of age 1+ by repeated observations in Lake Kursin in 2001 and evaluated as 15.60 days/sclerite between June 9 — July 1, 7.52 days/sclerite between July 1–21, and 7.94 days/sclerite between July 21 — August 30; on average one sclerite was formed in 10.35 days. The results demonstrate longer time of sclerites forming than reported earlier by G.V. Bazarkin (2003).
During spring-summer flood (in mid May — July), transit underyearlings of coho salmon, having or having no scales, migrate to Lake Kurazhechnoye at the lower Kamchatka River, where resident coho salmon never spawn. In this case, additional zones of closely–spaced sclerites (ZCS) can be formed on their scales because of feeding change (additional ZCS of the 1st type). Seasonal growth restarts and annual zone of close sclerites (annual ring) forms in May (or in early June for a part of juveniles) on scales of yearlings and elder coho salmon wintered in Lake Kurazhechnoye. In late July — August or sometimes later, other additional ZCS could form on the scale of juvenile coho salmon (ages 1+ and 2+) in the lake (additional ZCS of the 2nd type) because of their switching to feeding by fish (ninespine stickleback Pungitius pungitius, threespine stickleback Gasterosteus aculeateus, and smelt Hipomesus olidus). Rate of the sclerites forming was examined for the coho juveniles of age 1+ in Lake Kurazhechnoye in 2001 and evaluated as 8.52 days/sclerite, on average (one sclerite was formed in 9.18 days between June 13 — July 5 but in 7.86 days between July 5–23).
ENVIRONMENTS OF FISHERIES RESOURCES
Parasitic fauna of marine fishes in the northwestern Japan Sea is studied since 1929, when its investigation was started by E.M. Lyayman. The results concerning acanthocephalan worms were presented in several publications, including the papers about parasitic fauna of certain fish families or in certain areas of the Sea and the first description of a new species as Echinorhynchus theragrae from walleye pollock. This information is catalogued by E.M. Didenko and G.G. Shevchenko (1999), who presented a list of 25 Acanthocephala species from marine and anadromous fishes, including 4 unidentified ones. The study is continuing with expanding of the species lists for the region and for the hosts. New summary of all available data on acanthocephalan worms is presented, with quantitative data on their contamination of marine, anadromous and semi-anadromous fishes in the northwestern Japan Sea. In total, 2507 fish specimens belonged to 70 species, 53 genera, 25 families, and 13 orders were investigated in the period since 1997 to 2018 and 38 species of acanthocephalan worms were found belonged to 13 genera, 7 families, 4 orders, and 2 classes, mostly to the geni Echinorhynchus (8 species) and Corynosoma (5 species). Among these 38 species, 13 ones are new for the northwestern Japan Sea (Acanthogyrus (A.) lizae, Neoechinorhynchus agilis, Echinorhynchus lotellae, E. yamagutii, Pseudorhadinorhynchus samegaiensis, Metacanthocephaloides zebrini, Metacanthocephalus pleuronichthydis, Rhadinorhynchus cololabis, Andracantha mergi juv., Bolbosoma nipponicum juv., Bolbosoma sp. juv., Corynosoma osmeri juv., C. validum juv.) and 3 are noted for the first time in marine fish of the Japan Sea (E. yamagutii, A. mergi, C. validum). Intermediate hosts are determined and spatial distribution is described for each species. The most of acanthocephalan species are hosted by the fishes of families Pleuronectidae, Salmonidae and Gadidae (15, 14 and 13 species, respectively); on opposite, the fishes of family Trichodontidae are infested by 2 species only. New hosts are determined for 19 species of acanthocephalans. Mass contamination of fish by E. gadi, E. cotti, C. strumosum juv., and B. caenoforme juv. is detected.
Phenomenon of anomalous oceanographic conditions in the Bering Sea in 2018 is considered, with heightened air and water temperature and very low ice cover, as well as its consequences for the water structure, circulation, and chemical properties. These extreme conditions were formed on the background of warming tendency observed in the Bering Sea since 2014, but they were exceptional even relative to this background: deflections of some parameters from their normal values exceeded the standard deviations more than twice (> 2s). The main reason for such conditions was the southern winds prevalence over the entire Sea in winter, in opposite to usual regime when the southern winds blew over its southeastern part only; another factor was strengthened advection of the oceanic waters, still abnormally warm after the period of extreme warming in the North-East Pacific in 2014–2016. As the result, the ice cover in winter and spring was more than twice lower the normal values, the air and water temperatures through the year were above their normal values in 15 and 5 degrees Celsius, respectively. The winter convection was weakened that caused deepening of the cold subsurface layer core and prevented forming of the cold near-bottom water masses on the shelf that was usual for the Bering Sea. Under this considerable redistribution of the water density coupled with unusual wind regime, the water circulation changed, in particular in the northern Bering Sea where the Navarin Current were weakened or even absent and the northward water transport was realized through the eastern shelf delivering to the northern shelf and Bering Strait the coastal waters from Alaska instead of the deep-water basins waters, as usually. Strong advection of the oceanic waters through the Aleutian Straits promoted growth of nutrients concentrations and lowering of oxygen content in the intermediate layer of the Bering Sea. These extreme oceanographic conditions in the Bering Sea in 2018 were statistical outliers, atypical even for recent period of warming, but such conditions would be expected frequently if the warming will continue. Thus, phenomenon of the year 2018 could be useful for understanding and prediction of the oceanographic regime reconstruction in the nearest future.
New data on matter and energy transfer between major components of the Okhotsk Sea ecosystem are obtained on the base of trophodynamic modeling, taking into consideration their production and food consumption rates. The main trophodynamic relationships in the pelagic and bottom communities are determined from observations on zooplankton and nekton abundance, organic carbon content, food habits of marine organisms, and their isotope composition in 2000–2014. The total zooplankton production in the entire Okhotsk Sea in these years is assessed as 2616 . 106 t in raw weight, including 2275 . 106 t for non-predatory plankton, and 341 . 106 t for predatory plankton. So high total production of zooplankton is conditioned by favorable environmental conditions and dominance of high-productive species. Taking into account the rate of zooplankton consumption by predators, only 22.4 % of the total annual zooplankton production was consumed annually, with 16.2 % grazed by predatory plankton and 6.2 % by nekton. In carbon units, 831.0 . 106 tC was produced annually in the Okhotsk Sea at the first trophic level, 177.4 . 106 tC at the second trophic level, 18.1 . 106 tC at the third trophic level, 0.74 . 106 tC at the fourth trophic level, and 0.016 . 106 tC at the fifth trophic level. Pelagic nekton consumed 159 . 106 tC annually. The nekton prey included 85.5 % of zooplankton, 12.8 % of nekton, and 1.7 % of zoobenthos, by biomass. The main part of zooplankton consumed by nekton (50.7 %) was grazed by walleye pollock, 18.9 % by herring, 16.6 % by squids, 7.6 % by capelin, 5.3 % by deep-sea smelt, and 0.9 % by salmons. The total annual production of organisms in the epipelagic layer of the Okhotsk Sea exceeded 109 tons of C (1027.4 . 106 tC/year equal to the biomass of 17.85 . 109 t in wet weight). Primary production is estimated as 67.60 % of gross production in carbon units, microheterotrophic organisms produce 13.30 %, dominant zooplankton groups — 18.60 % (copepods 11.40 %, euphausiids 5.50 %, sagittas 1.20 %, and hyperiids 0.50 %), the portion of nekton production is estimated as 0.13 % of gross production.
The Vostok Bay was surveyed on March 16–18, 2016 with measuring of water properties profiles by oceanographic sondes Sea-Bird SBE-19plus V2 and Rinko Profiler ASTD-102 with sensors of pressure, temperature, conductivity, turbidity, chlorophyll fluorescence, dissolved oxygen, and photosynthetically active radiation (PAR) and collecting of water samples by SBE-32 carousel sampler with 10 liter bottles for further measuring of nutrients (P, Si and N in forms of nitrate and ammonium) and chlorophyll a concentration and phyto- and zooplankton abundance and species composition. Assimilation number (Pb ) of phytoplankton was determined using the optical sensor of dissolved oxygen mounted on logger Rinko AR01-USB and primary production was calculated from the measured values of Pb , Chl a and PAR. Values of primary production ranged from 200 to 2100 mgC/(m2.day). The highest phytoplankton growth was detected at the depth of 8–10 m in the northern Vostok Bay and 10–16 m in its southern part. The total daily production of phytoplankton within the Bay was estimated as 12.5 tC. Species composition of phytoplankton was formed mainly by diatoms (Bacillariophyta) and dinophytes (Dinophyta). The highest biomass of raw phytoplankton was registered at the sea surface, whereas the highest values of chlorophyll concentration occurred mainly at the bottom of the bay. Species composition of zooplankton was typical for spring season, with domination of copepods presented mainly by neritic species; its biomass was in 12 times lower than the phytoplankton biomass, on average. There was concluded that photosynthetic activity of phytoplankton was limited by nitrate availability, therefore it was intensified by penetration of relatively cold, nitrogen-rich waters from the deep-water sea to the Vostok Bay.
The Novik Bay is the largest one among the inlets of Russky Island in Peter the Great Bay. This water area is actively used for aquaculture and commercial and recreational fishery and attracts many tourists, so permanent monitoring of its water quality is necessary. Current environmental situation in the Novik Bay is assessed using microbiological indicators. The following parameters are used: total number of heterotropic bacteria, number of coliform bacteria, and number of metal-resistant microorganisms as indicators of oil and phenolic pollution. The water samples were collected in spring and autumn of 2017 and in spring and summer of 2018, following the standards GOST 31862 and GOST 31861. The number of microorganisms was determined by standard microbiological methods of sowing. The total number of heterotrophic bacteria corresponds to the requirements for oligo- or mesosaprobic waters. The number of metal-resistant microorganisms indicates that the waters of the bay are not subjected to industrial effluents and other man-made effects, its pollution by oil products is noticeable in some local areas only but the major part of the bay is low-polluted. In comparison with the data of previous chemical-ecological and microbiological tests, these assessments show better condition of the Novik Bay waters.
AQUACULTURE
Growing of cherry salmon juveniles under two different temperature regimes at the salmon farms Anivsky and Okhotsky in the fish-rearing cycle of 2016–2017 is analyzed. Data on cherry salmon growing for other fish farms of Sakhalin region collected in 1995–2017 are considered, as well. The periods of fish feeding and dynamics of their growth varied significantly in dependence on temperature conditions. The feeding started in April-May at the cold-water fish farms (Anivsky, Lesnoy, Sokolovsky, Urozhainiy) where the water temperature lowered in winter to 0.2–0.3 о С, but in February at Reidovo fish farm where the water temperature were not lower than 2 о С and in January at the most warm-water Okhotsky fish farm with the temperature never lower than 6.5 о С. In accordance with growing conditions, the growth rate of juveniles was high in winter month at the warm-water fish farms, where the ground water was used for rearing, but increased since May-June at the cold-water fish farms using natural heating of the river water. However, several cases were noted when the fish that accumulated less than 500–700 degree-days released from cold-water fish farms in June-July were larger than those from warm-water fish farms. Thus, cherry salmon is the only species among pacific salmons whose juveniles can be successfully grown at any temperature regime and consequently at any fish farm. This ability is reasoned by earlier spawning (along with pink salmon) and long period of development in rivers. At cold-water fish farms, the best results for cherry salmon growing could be achieved with the eggs planting in late August-September, whereas the time of eggs planting is not significant for warm-water fish farms.
Early stages of gametogenesis in young chum salmon are investigated under various temperature regimes at three fish farms of Sakhalin region and in laboratory conditions. In all cases, sex differentiation started after the mass hatching, the age of differentiation varied from 65 to 213 days, but the sum of accumulated degree-days was rather stable — from 620.6 to 669.1. The period from the beginning of sex differentiation to the beginning of previtellogenesis lasted 27–144 days depending on conditions, even for fish in the same fish farm. The lower was the water temperature after the beginning of sex differentiation, the smaller sum of degree-days was accumulated by fish before the beginning of previtellogenic growth of oocytes and the shorter was the period of oocyte growth before the fish release from the farm. The period of previtellogenesis in chum salmon always began before the end of larval period, when weight of the yolk sac was from 1.8 to 18.2 % of the total body weight.
PROMRYBOLOVSTVO
Numerical model of trawling system is developed on the base of equilibrium principle, using F.I. Baranov’s scheme of its power and geometric parameters interdependence. The model application to bottom trawling takes into account the effect of bottom grounds on the resistance force and expansion force of the trawling system. Algorithm is proposed for calculation of operating parameters of bottom and midwater trawls, with an operation to minimize the error of iteration. The model and the calculation algorithm were tested in MS Office Excel environment, using Visual Basic programming, and showed good convergence of the calculated and experimental data that indicates reliability of the model. This algorithm and the program for calculation of operating parameters could be used for trawl designing, in accounting surveys to determine the trawl opening, and in educational process for training the industrial fishery scholars.
TECHNOLOGY FOR PROCESSING OF AQUATIC ORGANISMS,
Antimora microlepis is considered as a new object of deep-water fishery. Its body length in the catches of 2018 was 40–80 cm, on average 56 cm, weight — 570–5670 g, on average 2170 g. Water content of its meat was 81.6 % that is similar to the meat of cod (82.1 %) but lower than the water content for other deep-water fish species. The muscle tissue of А. microlepis is lowcalorie and distinguished by medium protein content (17.1 %) and low fat content (0.4 %). The proteins have standard number and ratio of essential amino acids, the index of ECB is 114.8 %. Among fatty acids of the meat lipids, PUFAs dominate (49.4 %), mainly omega-3 family, but their content does not exceed 0.2 g per 100 g of meat because of low fat content. The meat of A. microlepis could be a source of sodium and copper, these metals content in 100 g of muscle tissue satisfies the daily needs of human body by 14.1 % and 18.0 %, respectively. Because of high protein content and low fat content, the meat of A. microlepis can be considered as a dietary fish raw material for both general and specialized products.
METHODS OF INVESTIGATIONS
Structure of the databases «Zooplankton…» and «Nekton trophology» is described and some techniques are proposed for nekton studies using these bases in conjunction with the database «Marine Biology». All three databases are regularly updated. The bases «Zooplankton…» and «Nekton trophology» contain raw data on plankton and feeding of nekton collected in the North Pacific and the Okhotsk, Bering and Chukchi Seas in 1984–2018. The «Nekton trofology» database contains information for 97 species of nekton, mostly for mass species (72–78 % of samples belong to 5 most numerous species), and 156 species of prey, including 27 species of Copepoda, 7 species of Euphausiacea, 9 species of Amphipoda, 14 species of Decapoda, 6 species of Coelenterata, 15 species of Cephalopoda, and 60 species of Pisces, other groups of prey are represented by 1–2 species. The data are spatially sorted by biostatistical areas and their sub-areas, in total 64 sub-areas in the Okhotsk Sea, 32 areas in the Bering Sea, 30 areas in the North Pacific, and 5 areas in the Chukchi Sea. Mean depth is determined for each sub-area. Method of spatial distribution mapping is demonstrated with using the sub-areas as integral stations or the 1-degree grid for Surfer software. Technique of regional inventory is explained with summarizing and averaging the data and calculation of various indicators as plankton–nekton ratio, etc. The 1-degree trapeziums are numbered for easier usage. Some useful examples are presented with the author’s comments (showing his personal opinion).
ISSN 2658-5510 (Online)