Prespawning Period Research Articles

Biochemical and hematological parameters of the roach Rutilus rutilus heckelii (Nordmann, 1840) from the Sea of Azov stock in the spring season of 2020–2021

This work presents the results of the investigation of the physiological state of the roach Rutilus rutilus heckelii breeders from the Sea of Azov stock during the spawning period. It has been established that, in the spring season of 2020 and 2021, the content of proteins and lipids in fish tissues, as well as hematological parameters in all investigated roach specimens from different water bodies were consistent with the average long-term values. The content of proteins in the muscles and liver of roach does not differ by sex. A higher protein content in the gonads of females is characteristic of the pre-spawning period due to the process of gonad maturation. The high content of lipids in the gonads of males apparently results from the lower energy consumption for maturation of the gonads and spawning. The average concentration of sodium and potassium ions decreased in comparison with the values obtained in 2020, while the concentration of chloride anions increased. It has been concluded that the physiological state of all investigated roach specimens was normal.

Assessment of the Effect of Catosal on the Stimulation of Ovogenesis in Sterlet During Pre-spawning Period

Optimization of the process of sterlet feeding in recirculating aquaculture systems allows improving the physiological status and pre-spawning performance of fish. The addition of the organophosphorus compound Catosal based on butaphosphamide to pre-spawning feeds leads to an increase in glycogenogenesis in hepatocytes, which manifests itself as a decrease in cell and nucleus area (by 1.20 and 1.31 times), stabilization of nucleoplasmic ratios (0.28-0.25). Butaphosphamide also causes an increase in hemoglobin and serum protein concentrations by 6.1 g/L and 3.92 g/L, respectively. An increase in the live weight of sterlet by 98.0 g and an absolute increase in weight by 1.96 g associated with an improvement in hematological parameters was observed. The excess phosphorus in the form of butaphospham, which is not involved in the process of glycogenesis, is transported to gonads and stimulates vitellogenesis. The acceleration of oocyte development is determined upon reaching the optimal polarization coefficient (0.05≤Pc≤0.10, category II).

О ПЛОДОВИТОСТИ СЕЛЬДИ-ЧЕРНОСПИНКИ ALOSA KESSLERI KESSLERI (GRIMM, 1887)

The article highlights the results of studying the individual absolute fertility (IAF) of black-backed shad Alosa kessleri kessleri (Grimm, 1887). The data were obtained during the species’ spawning run in the Volga River. A positive correlation was established between IAF and the linear indicators, weight and age of producers. IAF ranged from 38.0 to 333.9 thousand eggs. The average absolute fecundity of herring varied from 38.8 to 259.2 thousand eggs. In the 1970s black-backed shad of 26-42 cm long had fluctuations in the average absolute fecundity from 88.4 to 258.5 thousand eggs. At the present stage, the size range of spawning shoals suggests that maturity in black-backed shad occurs at a body length of 22-45 cm, the reproductive capacity is regulated by early maturation. The results of studies on the fertility of black-backed herring of various lengths in 1 g of ovary have been obtained. There has been registered a wide range of fluctuations in the number of eggs (from 4033 to 14147 pcs). Differences in the size of ovaries indicate a qualitative definiteness of the physiological readiness of females in the pre-spawning period. The fluctuations in the average individual absolute fertility were revealed depending on body weight and age. Fertility in one-size groups and the reproductive capacity of the population as a whole change due to habitat conditions. The conditional indicator of the population fertility was calculated. The results of the obtained fertility data compared with the data of previous years indicate a 1.5-fold decrease in reproductive capacity of the population at the present time, which indicates a stressed state of the reproductive capacity of female species

ОПТИМИЗАЦИЯ ЭТАПОВ ПРЕДНЕРЕСТОВОГО СОДЕРЖАНИЯ И НЕРЕСТА ТИЛЯПИИ ПРИ ТОВАРНОМ ВЫРАЩИВАНИИ

The article describes the process of commercial fish production in modern aquaculture, which requires high technologies and significant input. Optimization of technological processes while breeding fish is a necessary condition for the development of the industry. It is difficult and virtually impossible to develop a universal production pattern, this is why it is reasonable to split the whole process into several optimization tasks corresponding to each of the stages of the technological cycle. It is proposed to regulate such indicators as the level of feeding, pH value, age of producers as control actions at the stages of pre-spawning and spawning periods. The possibility to use the mentioned parameters for stage optimization, as well as for selecting the best values for each of the factors was assessed. The optimization target is to define the optimal amount of viable eggs, which would correspond to the minimal prime cost. It has been demonstrated that the optimal feeding level for the producers equals to 4 – 4.5 per cent of the fish body weight. The increase in the feeding level influences the fertility of producers insufficiently, inflating the costs. It has been found out that 12 – 24 months old producers have the best reproduction indices. The preferred quality and the vital capacity of spawn received from the producers within this group have also been registered. Another factor which may be used in order to control the process is the pH of water in pools. Regardless of the fact that tilapia producers are relatively undemanding to the habitat conditions and resistant to pH values, it is possible to single out the optimal range of this factor. It corresponds to pH values between 6 and 7.5. This is when the best rates of eggs fertilization and survival are observed.

Характеристика репродуктивних показників та якості статевих продуктів самиць коропа (Cyprinus carpio (Linnaeus, 1758)) за використання в годівлі голозерного вівса впродовж переднерестового періоду

Purpose. To investigate the effect of feeding carp with hulless oat during pre-spawning period on the reproductive functions of female carp as well as on qualitative characteristics of the obtained eggs. Methodology. The objects of the study were females of the Nyvky intra-breed type of the Ukrainian scaly carp breed, which were kept during the pre-spawning period in pond conditions of the State Enterprise “Nyvka” of the Institute of Fisheries NAAS of Ukraine. Females were divided into 3 groups. The first group (Experiment I) was fed with 30% hulless oat, the second (Experiment II) with 100% hulless oat. The control group of fish (Control) was fed with a grain mixture. Experiments were conducted in accordance with current methods used in aquaculture. The mass fraction of protein was determined by the Kjeldahl method, the fat content was determined by S.V. Rushkovsky method. Determination of total lipids was performed by the Folch method. Sampling of water for chemical analysis and its processing in the laboratory was carried out according to O.A. Alokin method according to the Standard of the Ministry of Agrarian Policy of Ukraine. Analytical processing of the material was performed using MS Excel. The criteria for the analysis of studied parameters were their mean values (M) and standard deviations (m). Results. According to studies, the use of 30% hulless oat in the feed of female carp during the pre-spawning has a positive effect on their production of eggs, as evidenced by an increase in relative fertility by 15.6%, fertilization rate by 4.0%, and survival of the obtained 3-day-old larvae by 5.0%. According to biochemical parameters of eggs, there was an increase in the amount of essential amino acids by 3.04 and 2.01 g/100 g of protein, and fractions of lipids responsible for energy storage, in particular triglycerides, by 11.56 and 5.62%, phospholipids by 3.65 and 2.37%, and fatty acids by 5.33 and 3.11%, respectively, according to the experimental groups. Instead, cholesterol levels decreased by 13.4 and 25.2%. Temperature, oxygen, and hydrochemical regimes in the hatchery were within aquaculture standards, except for permanganate oxidation and total iron and chlorine ions. Originality. The prospects of using hulless oat in feeding brood carp were studied in Ukraine for the first time. The analysis of reproductive parameters of female carp as a result of experimental feeding and evaluation of the qualitative characteristics of eggs and offspring obtained by the method of factory reproduction was conducted. Practical value. The results of a comprehensive assessment of aquaculture and biological parameters will provide recommendations for the use of hulless oat in feeding female carp during pre-spawning period. Key words: carp, feeding, hulless oats, reproductive parameters, survival, amino acid and lipid composition of eggs.

ФИЗИОЛОГО-БИОХИМИЧЕСКИЕ ИЗМЕНЕНИЯ КАСПИЙСКОЙ ОБЫКНОВЕННОЙ КИЛЬКИ (CLUPEONELLA DELICATULA CASPIA SVETOVIDOV) В РАЗЛИЧНЫЕ ПЕРИОДЫ ГОДОВОГО ЦИКЛА

The article considers studying the physiological and biochemical parameters of the common sprat (Clupeonella delicatula caspia Svetovidov) taken in the western part of the Middle Caspian Sea at different periods of the annual cycle. There were studied the species in the pre-spawning state, at the beginning of spawning, at the feeding stage and at the pre-wintering stage. 
 In fish muscle tissue the content of water-soluble protein and total lipids was determined. In the pre-spawning period, in male common sprat was recorded a positive correlation (p < 0.05) between the weight of fishes, fishing length and content of total lipids in muscles (r = +0.5206) and (r = +0.5039), respectively. In females no statistically significant dependence of the size-weight parameters and lipid content in muscles were recorded, which is probably due to the fact that lipids in their bodies were spent for energy needs, and to a greater extent than in males - for the generative function. In a comparative aspect, in the muscles of males and females no significant differences in the content of total lipids and water-soluble protein in the pre-spawning period were found. At the stage of the beginning of spawning, a decrease in total lipids and water-soluble protein was noted in the muscle tissue of the studied fishes, which is associated with an increase in energy consumption for sweeping out sexual products. During the feeding period the common sprat was characterized by an intensive accumulation of lipid reserves; the content of total lipids and water-soluble protein in the muscles increased with increasing length of individuals. In the pre-winter period stabilization of muscle lipid and increase in protein reserves were recorded, which is necessary for fish to ensure a normal existence 
 in the subsequent stages of the annual cycle.

The influence of natural vs anthropogenic factors on trace metal(loid) levels in the Mussel Watch programme: Two decades of monitoring in the Spanish Mediterranean sea

The spatial distribution and temporal trends of trace metals (i.e. Cd, Cu, Hg, Pb and Zn) and a metalloid (i.e. As) along the Spanish Mediterranean coast from 1993 to 2013 are presented with a new estimation of their background levels monitored using wild mussels. Over a 20 years period, yearly mussel monitoring was undertaken with a rigorous field sampling protocol using 3 pooled samples strategy (3 x n = 80, with 8 mussels in the 3.0 to 3.9 size categories at each site), obtained in the pre-spawning period (May–June) to minimize biological factors and seasonal variability, which is a fundamental element of the international programme. Spatial distribution was characterized every 5 years and temporal trends were determined in 11 locations. The main aims of the present long term study are to evaluate the environmental status of different coastal locations regarding trace metal levels and follow the evolution of these levels over time after the implementation of regulatory measures. Regarding spatial distribution, the highest values for Cd, Cu, Hg and Pb were found close to known highly anthopogenic cities or shipyard areas. However, As and Zn did not strictly follow this pattern, showing natural increased concentrations in the Levantine Balearic and Strait of Gibraltar-Alboran Sea demarcations respectively. These distributions are associated with the conjunction of two geological formation inputs (Massif Central in France and Iberian Pyritic Belt in Spain) and the oceanographic conditions in the adjacent coastal area. In the case of temporal trends, metal concentrations decreased significantly over time in most stations, confirming the effectiveness of the regulatory measures and prohibitions established under European legislation. Concentrations of Pb were above the established thresholds for human consumption in only 12–14% of the sampling areas. With the information obtained for this study, we estimate background concentrations and propose new Background Assesment Criteria (BAC) for the Spanish Mediterranean coast as a threshold criterion: 1.62 mg/kg d.w. for Cd, 8.75 mg/kg d.w. for Cu, 0.202 mg/kg d.w. for Hg and 2.83 mg/kg d.w. for Pb.Exceptions should exist for As and Zn, for which there should be different levels in each demarcation, due to the geological, hydrological and oceanographic peculiarities of the Spanish coast. For the Levantine-Balearic demarcation, the proposed background concentrations are 117 mg/kg d.w. for As and 200 mg/kg d.w. for Zn., whereas in the Strait of Gibraltar-Alboran Sea demarcation, they are 27.5 mg/kg d.w. for As, and 471 mg/kg d.w. for Zn. This work demonstrates the vital importance of defining the background levels of metal(loid)s at a regional or subregional level because, for areas not affected by anthropogenic causes which have high values as the result of natural processes, this would avoid the risk of constantly surpassing the levels proposed in directives.

Characteristics of biochemical parameters of sperm production of carp sire when using hulled oats in feeding during the pre-spawning period

The restoration of freshwater aquatic life and the cultivation of highly productive sires is a key stage in the process of restoring a new generation of fish, thus, the task of increasing fertility is always relevant for the fishing industry of Ukraine. The purpose of the study is to conduct an in-depth analysis of the physiological characteristics of ejaculates of respiratory and reproductive capacity, to explore the activity of enzymes of the respiratory chain of mitochondria, to determine the percentage of sperm survival when using pre-cleaned oats, as the main component in the diet of carp during the pre-spawning period In the study, males of the Nyvka interbreed type of Ukrainian scaly carp breed were used, which were kept during the pre-spawning period in pond conditions of the State Enterprise “State Farm “Nyvka” IRG NAAS. Individuals were divided into 3 groups. The first group (Experiment I) was fed 100% hulled oats, the second (Experiment II) – 30% and the control group of fish (Control) was fed a grain mixture. The quality of male carp sexual products was assessed by determining the effect of adding hulled oats to their diet during the pre-spawning period. Indicators of sperm motility and fertilizing ability, the content of γ-, β- and α-globulins, albumin, prealbumin and physiological characteristics of ejaculates of respiratory and reducing capacity, the activity of enzymes of the respiratory chain of mitochondria (COX and SDH) were explored. Considering the increase in the productivity of fish sperm, in particular, the increase in the number of sperm with rectilinear motion, the decrease in the number of lifeless sperm and changes in the protein formula of germ cells, it was established that it is advisable to add hulled oats to the main diet in the amount of 30%. According to the results of the conducted research, it was established that the addition of hulled oats to the fodder during the pre-spawning period has a positive effect on the quantitative and qualitative indicators of male carp sexual products, the results of the research can be useful for both students and workers of the fish processing industry of Ukraine

A Histopathological–Biochemical Health Assessment of Blue Mussel Mytilus edulis

Aquaculture of the blue mussel Mytilus edulis in the Gulf of Maine is a growing industry at a time when wild mussel populations are threatened by a rapidly changing ocean. Intertidal mussel beds have largely disappeared in the region raising concerns over the long-term viability of mussel farming. Histology and lipid fatty acid analysis were used to assess gametogenesis, energy investment, and pathology of farmed mussels collected twice monthly for three years in Casco Bay, ME. Energy investment in reproduction and storage differed significantly between years, suggesting interannual variability. Wet weight of fatty acids such as DHA and EPA corresponded to pre-spawning periods, when gonad tissue was most abundant. Overall, pathology assessment showed low levels of common pathogens, parasites, and cellular abnormalities. The survey did, however, reveal high levels of oocyte atresia, a probable indicator of physiological or environmental stress from unfavorable spawning conditions. In addition, the presence of the potentially damaging digenetic trematode Proctoeces maculatus was documented using histology, marking the northernmost detection in the Northwest Atlantic and a likely climate-driven range expansion. These trends may signal a challenging future for blue mussels in the Gulf of Maine. Forward-looking farm mitigation practices informed by these results should be developed to ensure future sustainability of this industry.

Length weight relationship and relative condition factor of goby fish, Paracheaturichthys ocellatus (Day 1873) from the creeks of Mumbai

Length Weight Relationship of Paracheaturichthys ocellatus (Day1873) from the creeks of Mumbai was carried out from July 2010 to September 2011. The males ranged in the length of 66-182 mm and weight 1.152-54.801g while females ranged in the length 66-153mm and weight 2.209-38.383g. The juveniles ranged in the length range of 52-65mm and weight of 1.775-3-545g. The parabolic equation was W= -5.1742L3.1041 with high correlation of 0.9961 indicating that fish increased in body weight as it grows in total length in the total population. The coefficient of regression b was 3.1041 for all fishes combined together showing a positive allometric growth. The relative condition factor for males was 1.0126, females was1.0375 and 1.0013 for juveniles. Sex wise analysis of relative condition values revealed that mean Kn values in females (1.0375) was higher than that of males (1.0126). In present study Kn values were higher in males during pre-spawning period while in females it was during post spawning period. In males higher Kn values was observed in the length group of 106-115mm while in females it was 66-75mm. Relative condition factor was never less than 1 through the period of study hence it was in good condition irrespective of feeding or reproductive condition.

The Effects of Water Temperature on the Timing of Spawning and Spat Settlement of the Yesso Scallop (Mizuhopecten yessoensis Jay, 1857) in Minonosok Cove (Posyet Bay, Peter the Great Bay, Sea of Japan)

The effect of water temperature on the timing of spawning and spat settlement of the Yesso scallop (Mizuhopecten (=Patinopecten) yessoensis Jay, 1857) in Minonosok Cove (Posyet Bay, Peter the Great Bay) has been studied based on the most complete dataset of observations for 1970–2011. The date of onset of spawning varied from May 1 to June 9 (within 40 days) and the onset of spat settlement varied from June 4 to July 5 (within 32 days). It has been found that the timing of spawning shifts to later dates due to the longer preceding cold periods with a greater accumulated sum and lower average values of below-zero temperatures, due to the short pre-spawning periods (from the date when the sea surface temperature (SST) reaches 0°C to May 1) with decreased sums and low average temperatures over these periods, as well as due to the decreased sums of temperatures in April. Later settlement dates were also recorded in the years with severe winter conditions. The onset of settlement shifts to a later date also in case of low average above-zero temperature in the pre-spawning period (correlation coefficient (R) = –0.46). Early settlement on collectors was observed in the years when SST reached 0°C on earlier dates in spring (at the Posyet Hydrometeorological Station). The higher the sum of above-zero temperatures was accumulated by May 1 and June 1, as well as in April and May, the earlier the scallop spat settled on collectors (R = –0.58, –0.60, –0.55, and –0.42, respectively). Prognostic equations are proposed to predict the dates of the onset of spawning and spat settlement with a lead time of 10 and 15 days, respectively; the equations are tested on the results of a correlation analysis. The accuracy of these predictions based on 10-year independent samples constitutes 70% for the spawning onset date and 60% for the spat settlement onset date.

Assessing reproductive effects on fish populations: an evaluation of methods to predict the reproductive strategy of fishes.

Many environmental monitoring programs include an assessment of the health of fish populations using a sentinel species and include an indicator of reproductive potential. Knowledge of the reproductive strategy of the fish species is critical for data interpretation but is not always known. The reproductive strategy of a species can be determined from detailed histological analyses of ovaries throughout the reproductive cycle; however, these studies can be costly and can delay the implementation of a monitoring program. Three quick and cost-effective methods of predicting the reproductive strategy (annual single spawning or annual multiple spawning) are evaluated in this study using predicted probabilities from binary logistic regression models as a means of classifying the reproductive strategies of 18 different fish species in Atlantic Canada. The first method was based on the hypothesis that the variability in the ovary weight-body weight relationship in prespawning females is higher in multiple spawners. This method did not have a good classification rate due to some multiple spawners having low variability. The other two methods involved predictor variables representing the proportion of oocytes in different stages of development and predictor variables representing the distribution of oocyte sizes during the prespawning season for 111 fish (25 different samples for species). Predicted probabilities from these regression models could be used to correctly classify the reproductive strategies of all 25 samples (development stage model) and all but one sample (oocyte size distribution model). These models can be used to estimate the reproductive strategy of a species from a single sample of fish collected during the prespawning period to support species selection and data interpretation in environmental monitoring programs.

The Numerical Model of Fish Growth Dynamics (On the Example of Okhotsk Atka Mackerel Pleurogrammus azonus)

A complex model of the system is proposed, the dynamic variables of which are the length, fish’s weight and the weight of its food lump. The model’s mathematical formalization is performed in terms of the ordinary differential equations apparatus. The solution to the parametric identification problem of the model is based on the author's representative sample for long-term observations. Computational experiments show that the representation of the indicators dynamics fish’s weight, length and the weight of the food lump is determined by some functions of the components from this set. The hierarchy of relationships between indicators determines the structure of these functions. It turned out that the dynamics of length is practically independent of the food lump’s weight, which in this case is an external energy source of the body’s vital activity. The energy “mediator” is body weight. The dynamics of body weight is determined by the weight of the food lump and the actual body weight. The negative coefficient calculated when solving the problem of parametric identification with body weight reduces the intensity of its dynamics. It seems that this coefficient reflects the expenditure of the body on the processes of its metabolism. The dynamics of length has a cumulative character (only positive gains). The body weight dynamics is determined by the accumulation and loss of vital activity of organic matter (positive and negative gains). The jump in the dynamics of weight is due to the high energy costs of fish for the intensive formation of reproductive products in the pre-spawning period and the energy costs of subsequent spawning. The dynamics of the food lump depends on the weight of the fish and is regulated by seasonal endogenous and exogenous rhythms of the fish's life cycle. Weight gain largely determines the intensity of nutrition than the diet determines the rate of weight growth. A measure of the adequacy between the model and sample distributions here is the correlation coefficient between them. In the case under consideration, it is close to its maximum (single) value, which indicates their high proximity.

EFFECTS OF THE WATER TEMPERATURE ON TIMING OF SPAWNING AND THE SPAT SETTLING FOR YESSO SCALLOP (MIZUHOPECTEN YESSOENSIS JAY, 1857) IN THE POSYET BAY (PETER THE GREAT BAY, JAPAN SEA)

The water temperature influence on timing of spawning and the spat settling is considered for yesso scallop (Mizuhopecten (=Patinopecten) yessoensis Jay, 1857) in the Minonosok Bay (Posyet Bay, Peter the Great Bay) on the data of observations in 1970–2011. The date of the spawning start varied from May 1 to June 9 (within 40 days) and the start of the scallop spat settling onto collectors of marine farm varied from June 4 to July 5 (within 32 days). Usually the spawning was delayed in the years with long cold season and big sum of daily temperatures below zero or low mean temperature in winter months and April, when the pre-spawning period with the temperature above zero before May 1 was too short. The spat settling was delayed in the years with severe winter or low mean temperature in the pre-spawning period (r = –0.46); the early settling was observed in the years with early warming above 0o C. The higher sum of positive daily temperatures accumulated till May 1 and till June 1, or within April and May, the earlier the spat settling on collectors (r = –0.58; –0.60; –0.55; –0.42, respectively). Prognostic equations for 10-day and 15-day forecasting of the dates of scallop spawning start and spat settling start are proposed and tested; accuracy of these forecasts is 70% for the spawning and 60 % for the spat settling.

Are we designing fishways for diversity? Potential selection on alternative phenotypes resulting from differential passage in brown trout

Fishways are commonly employed to improve river connectivity for fishes, but the extent to which they cater for natural phenotypic diversity has been insufficiently addressed. We measured differential upstream passage success of three wild brown trout (Salmo trutta) phenotypes (anadromous, freshwater-resident adult and parr-marked), encompassing a range of sizes and both sexes, at a Larinier superactive baffle fishway adjacent to a flow-gauging weir, using PIT telemetry (n = 160) and radio telemetry (n = 53, double tagged with PIT tags). Fish were captured and tagged downstream of the weir in the autumn pre-spawning period, 2017, in a tributary of the River Wear, England, where over 95% of tributary spawning habitat was available upstream of the weir. Of 57 trout that approached the weir-fishway complex, freshwater-resident adult and parr-marked phenotypes were less successful in passing than anadromous trout (25%, 36%, and 63% passage efficiency, respectively). Seventy-one percent of anadromous trout that passed upstream traversed the weir directly. Although the fishway facilitated upstream passage, it was poor in attracting fish of all phenotypes (overall attraction efficiency, 22.8%). A higher proportion (68.2%) of parr-marked trout that approached the weir were male and included sexually mature individuals, compared with that of freshwater-resident (37.8%) and anadromous trout (37.0%). The greater passage success of anadromous trout was likely due to their greater size and locomotory performance compared to the other phenotypes. Barriers and fishways can act as selection filters, likely the case in this study, and greater consideration needs to be given to supporting natural diversity in populations when proposing fishway designs to mitigate river connectivity problems.

Comparative Analysis of Expression of Some Protein Kinases and Protein Phosphatases in Lamprey Erythrocytes on the Course of Prespawning Period

Comparative Analysis of Expression of Some Protein Kinases and Protein Phosphatases in Lamprey Erythrocytes on the Course of Prespawning Period

Effect of melatonin and pinealectomy on gonadal activity during prespawning period of catfish (Heteropneustes fossilis)

Effect of melatonin and pinealectomy on gonadal activity during prespawning period of catfish (Heteropneustes fossilis)

The Trace-Element Content in the Pink Salmon Oncorhynchusgorbuscha (Walbaum, 1792) from the Sakhalin–Kuril Region

The contents of the trace elements Hg, Cu, Pb, Cd, Zn, and As were measured in the pink salmon Oncorhynchus gorbuscha (Walbaum, 1792), a common Pacific salmon species, which was kept in the net-pens of the Reidovy (Iturup Island) and Firsovka (Sakhalin Island) fish hatcheries in October 2016. The levels of the toxic elements Cd, Pb, As, and Hg in the pink salmon from the Sakhalin–Kuril region were found to meet the official health standard norms for seafood in the Russian Federation. At the same time, they were a few times higher than that in the pink salmon from ocean waters off the Kuril Islands during its anadromous migration and dozens of times higher than in the fish from the Sea of Japan that were caught off the Primorsky Krai coast during the pre-spawn period in different years. The greatest differences were recorded for lead, whose concentration in the muscles, liver, and eggs of the fish from the rivers of Iturup and Sakhalin was, respectively, 50, 40, and 60 times higher than that in the pink salmon from the Sea of Japan. The only trace element whose level in the pink salmon from the Sea of Japan exceeded that in the fish from Sakhalin and the Kuril Islands was zinc.

Copper effect on the biomarker state of the Mizuhopecten yessoensis tissues in the prespawning period

The aim of this study was to investigate the sensitivity of the marine scallop Mizuhopecten yessoensis to different copper concentrations (10 and 30 μgl-1) in the prespawning period. Reaction of the scallop to this effect was evaluated by a set of biomarkers, including general metabolism enzymes (acid and alkaline phosphatase activities - AcPase, ALP), and oxidative stress parameters (catalase antioxidant enzyme activity - CAT and levels of damage for DNA, lipids and proteins). Experiment results show that when copper is accumulated in tissues, enzyme activity changes are similar and have phasic character. The dynamics of these changes depends on the copper accumulation levels in tissues. Unlike enzyme reaction to copper accumulation, oxidative damage of biologic molecules changes in tissues in different ways. Copper enters into a scallop's organism, mainly through the gills, where there is a more expressed reaction of biomarkers compared to the digestive gland.

Fecundity of diploid and triploid Carassius gibelio (Bloch, 1782) females

Fecundity of diploid and triploid Carassius gibelio (Bloch, 1782) females