Perch Research Articles

Technical Efficiency of the Nile Perch Fishing Fleet on Lake Victoria: A Comparative Perspective on the Three Riparian Countries Kenya, Tanzania and Uganda

Technical Efficiency of the Nile Perch Fishing Fleet on Lake Victoria: A Comparative Perspective on the Three Riparian Countries Kenya, Tanzania and Uganda

Knowledge, attitudes and practices of fresh Nile perch value chain handlers towards food safety requirements in Uganda

In the continuum from ‘farm to fork’, the proficiency of food handlers in terms of knowledge, attitudes, and practices (KAP) is essential for ensuring improved food safety outcomes. This study evaluated the KAP of fresh Nile perch fish handlers regarding food safety requirements within Uganda. A cross-sectional survey involving fish handlers (n = 466) engaged in handling fresh Nile perch and fisheries products in both local and export market chains. The study was conducted at 30 gazetted fish landing sites on Lake Victoria, 15 licensed fish export factories, and 9 local markets authorized to sell fisheries products. Data on demographic, knowledge, attitude, and practices was collected using structured questionnaire. Demographic data was analysed using frequencies and percentages. Ordinary least squares bivariate and multivariate regression analyses were performed to determine factors associated with knowledge, attitudes, and practices regarding food safety requirements. Fish handlers (49.8 %) demonstrated good knowledge with the majority (74.6 %) from the export market chain. Majority (81.3 %) of market stall handlers had poor knowledge of food safety requirements. Most (68.2 %) fresh Nile perch fish handlers had limited awareness of food-borne pathogens. Only 31.8 % had knowledge about E. coli, Salmonella spp, and Staphylococcus spp. Furthermore, over 63 % believed that consuming contaminated fish could transmit HIV, Covid-19, and Ebola. Male gender, higher income, and advanced education were positively correlated with fish handlers' knowledge of food safety requirements. Fish handlers (57 %) in the local market chain exhibited poor attitudes. Being a male fish handler was significantly (β = 3.43, 95 % CI: 1.65–5.21, P = 0.001) associated with positive attitudes compared to being female. Education at different levels was significantly (Primary (β = 3.19, 95 % CI: 1.05–5.33, P = 0.004); Secondary level (β = 5.883, 95 % CI: 3.52–8.23, P = 0.001); Tertiary (β = 6.09, 95 % CI: 3.03–9.15, P = 0.001)) associated with positive attitudes compared to no education.Practices ensuring food safety were common in the factories and the export market. The study suggests the need for interventions that promote knowledge transfer and food safety culture, particularly in the local market chain.

Трематоды рода Apophallus (Trematoda: Heterophyidae) в фауне многоклеточных паразитов Perca fluviatilis (Perciformes, Actinopterygii) в дельте Волги

The living conditions of aquatic organisms in the Volga-Caspian Sea Shipping Canal are determined by a high level of complex multifactor anthropogenic load. As a link in a unified international transport system, the canal serves as an invasive corridor for the settlement of alien organisms, including parasites. The fauna of multicellular parasites Perca fluviatilis (Perciformes) in the canal area was studied. 6 taxa of parasitic organisms have been registered. The nematode Eustrongylides excisus occupies a dominant position in the fauna of macroparasites P. fluviatilis. An alien trematode, Apophallus muehlingi, was discovered associated with the invasive mollusk Lithoglyphus naticoides; the parasite has the status of a codominant species. A specific parasite widely distributed in perch fish populations in the Volga delta, Apophallus donicus, has not been registered. The high degree of invasion of perch by A. muehlingi during the three-year study period indicates the stability of the parasitic subsystem “A. muehlingi – P. fluviatilis”, previously uncharacteristic for this host species in the lower reaches of the Volga. Currently, more favorable conditions have developed for the invasion of perch A. muehlingi than A. donicus in certain areas of the Volga delta. Thus, structural changes were found in the host-parasite relationships systems of the trematodes of the genus Apophallus, which appear in the form of a partial restructuring of the species and host structure of the fauna of macroparasites P. fluviatils in the investigated area of the river. This situation is determined by factors that are largely anthropogenic in nature – changes in the living conditions of hosts and parasites, caused by a combination of fluctuations in the level of the Caspian Sea and the discharge of the Volgograd hydroelectric station, intensive shipping (large volume of cargo transportation) and high fishing pressure. The most likely significant additional factor of changes in the nature of infection of P. fluviatils by trematodes of the genus Apophallus is currently a decrease in the stocks of populations of some massive species of cyprinid fish – the second intermediate hosts of A. muehlingi, for which the parasite is defined as specific.

Climbing Perch Fish Sperm DNA (Anabas testudineus) Protection Using Cryoprotectant Agent

Sperm cryopreservation is a sperm storage method that needs to be developed to ensure the availability of climbing perch fish (Anabas testudineus) sperm considering the difficulty of providing quality broodstock. This study aims to determine the effect of several types and concentrations of cryoprotectants on the DNA integrity of climbing perch fish sperm after cryopreservation for 14 days at a temperature of -196 ℃. Analysis of sperm DNA integrity used the gel electrophoresis method. This research consists of four types of cryoprotectants; Each type of cryoprotectant consists of two concentration levels. The cryoprotectant concentrations used were DMSO (concentrations 10 and 20%), Methanol (concentrations 10 and 20%), Glycerol (concentrations 5 and 20%), and Ethanol (concentrations 5 and 15%) as well as control treatment and fresh sperm treatment. Based on the results of the DNA integrity analysis of climbing perch fish sperm, it showed that all sperm DNA samples did not form fragments, meaning that there was no damage to climbing perch fish sperm DNA in all samples tested, both fresh sperm samples and post-cryopreserved sperm samples.

Identification of Ectoparasites and Endoparasites in Snakehead Fish (Channa striata) and Climbing Perch Fish (Anabas testudineus) Caught in the Sebangau River of Indonesia

Ectoparasites are parasites that can infect the external organs of fish (skin, gills and the outer surface of the body) while endoparasites are parasites that infect the internal organs of fish. This study aims to determine the types of ectoparasites and endoparasites that infect snakehead fish (Channa striata) and climbing perch fish (Anabas testudineus). Sampling was carried out at the Sebangau River while the identification was carried out at the Fish Quarantine Station, Quality Control and Safety of Fishery Products in Palangka Raya. Examination of ectoparasites includes mucus, gills, scales, and fish fins. Examination of endoparasites by observing the organs of the fish such as liver, meat, intestines and stomach. There are eight types of ectoparasites in snakehead fish, namely Trichodina sp, Dactylogyrus sp, Gyrodactylus sp, Apiosoma sp, Tetrahymena sp, Aelosoma sp, Lamproglena sp, and Henneguya sp, while there are four types of endoparasites in snakehead fish, namely Camallanus sp, Procamallanus sp, Neoechynorynchus sp , and Senga sp. There are five types of ectoparasites in the climbing perch fish caught in the Sebangau River, namely Trichodina sp, Dactylogyrus sp, Aelosoma sp, Myxobolus sp, and Epistylis sp. Meanwhile, there is only one type of endoparasite that attack snakehead fish, namely Procamallanus sp. The total prevalence of snakehead fish’s ectoparasites was 81.7%, with an intensity level of 6.1 individual parasites per fish. The total prevalence of ectoparasites in climbing perch fish is 45%, with an intensity level of 5.4 individual parasites per fish. The total prevalence of snakehead fish endoparasites is 65%, with an intensity level of 9.8 individual parasites per fish. The prevalence of climbing perch fish’s endoparasites is 31.7%, with an intensity level of 19 individual parasites per fish.

Nile perch fish nuggets: Partial replacement of fish flesh with sesame hulls and sunroot — Quality assessment and storage stability

This study aimed to produce Nile perch fish nuggets by replacing a part of fish flesh with different concentrations of sesame hulls and sunroot to reach the optimal recipe. Chemical, microbiological, and sensory characteristics of nuggets were evaluated during 3 months of frozen storage at –18 °C. According to the obtained data on the chemical composition of raw materials, Nile perch flesh had the highest content of protein (20.21%), sesame hulls contained the highest amount of fat (13.54%), fiber (17.24%) and ash (16.11%), while sunroot tubers had the highest amount of carbohydrates (15.76%). Based on the sensory score, the acceptable replacement ratio for fish nuggets prepared with sunroot (T1) and sesame hulls (T2) was 10% and 7.5%, respectively. Thiobarbituric acid (TBA) analysis at zero time shows that the T1 samples had the minimum value compared to the T2 and control samples. During storage, the TBA levels increased slightly in all samples, but after three months T1 also showed the lowest value. The total plate count (TPC) and psychrophilic bacterial (PSY) count in the samples were affected by the period of frozen storage at –18 °C. The initial TPC and PSY loads were 2.32 and 2.02 log cfu/g for control; 2.24 and 1.72 log cfu/g for T1; 2.30 and 1.47 log cfu/g for T2, respectively. During storage, the values of TPC and Psy slightly decreased. In conclusion, this study succeeded in the replacement of Nile perch fish with sesame hulls and sunroot as new sources to improve the nutritional value and quality characteristics of fish nuggets.

Study of Reproductive Performance of Climbing Perch (Anabas Testudineus Bloch)

Climbing perch called Papuyu fish in South Kalimantan Indonesia caught in swamp waters, is a fish that is very popular with the community and has high economic value. Fish reproductive performance is very important to obtain information on the natural conditions of the reproductive status of climbing perch fish in the form of gonadal maturity level, and fecundity. This research aims to analyze the reproductive performance of climbing perch fish based on the level of gonadal maturity, gonadal maturity index and fecundity of climbing perch fish ( Anabas testudineus Bloch). The method used in this study was descriptive quantitative. Starting from the preparation of tools and materials, the measurement of fish reproductive parameters including gonadal maturity level, gonadosomatic index and reproductive fecundity were observed morphologically and analyzed descriptively. The results of the study, reproductive performance, the maturity levels of the gonads ranged from TKG II, TKG III and TKG IV. The gonadosomatic index ranged from 0.995-11.147%. are within the range of IKG values ​​of climbing perch fish. Fecundity in sample A ranged from 10,098-39,303 eggs with an average of 24,816 eggs and a gonad weight of 2.97g. Sample B ranged from 14,800-62,381 eggs with an average of 34,767 eggs with a gonad weight of 4.47g. Keywords: Reproduction, Climbing perch, gonads, fecundity. DOI: 10.7176/JNSR/14-4-03 Publication date: February 28 th 2023

Growth Performance and Survival of Climbing Perch (Anabas testudineus Bloch) Raised in Conventional and Bioflocs System

The aim of this research is to analyze the performance of growth and survival of climbing perch (Anabas testudineus Bloch) which was raised in bioflocs and conventional systems. It investigated the difference in the initial size of the fry stocked with climbing perch has effect. The experimental design used in this study was a Factorial Completely Randomized Design (CRD) with 2 factors and 3 replications: Factor A: climbing perch aquaculture Systems; A1: climbing perch in conventional system of; A2: the climbing perch in bioflocs system; Factor B: Initial Size of fry Stocking; B1: fry size 3 ± 0.5cm; B2: fry size 5 ± 0.5cm and B3: fry size 7 ± 0.5cm. The research was conducted for 90 days with daily growth parameters (SGR), weight and length growth, survival rate, food conversion, flocsvolume density (FVD), and main water quality parameters (water temperature, pH, dissolved oxygen and dissolved ammonia).The results showed that the bioflocs system was able to increase the average growth in the range of 12-67% with an average of 29.73% when compared to conventional systems. The highest value for the daily growth rate or Specific Growth Rate (%/day) was for fry with a size of 7 cm in the bioflocs system (8,419%). The fry size of 3 ± 0.5cm in the bioflocs system had the highest difference in standard length (4.33 cm) while the highest average length during maintenance was the seed size of 7 ± 0.5 cm in the bioflocs system. The survival results of climbing perch fish during the study were based on the highest score on the seed size of 3 ± 0.5cm in the bioflocs system. The survival range of the bioflocs system is 94.89 - 99.67% and that of the conventional system is 82.00 - 94.26%. Thus the bioflocs system is able to increase survival in the range of 5-14% when compared to conventional systems. The bioflocs system is able to provide better feed efficiency than conventional systems in the range of 34-39%. The average value of floc volume density (FVD) in the bioflocs system is in the range of 5.35 – 8.16 ml/L, which is still ideal but can still be improved. Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L. The temperature ranges in the studies on conventional and bioflocs systems are within the acceptable range for fish farming Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L.

Microplastics and Per- and Polyfluoroalkyl Substances (PFAS) Analysis in Sea Turtles and Bottlenose Dolphins along Mississippi’s Coast

Global plastic production and usage has increased annually for decades and microplastic pollutants (≤5 mm) are a growing concern. Microplastics in surface waters can adsorb and desorb harmful chemicals such as per- and polyfluoroalkyl substances (PFAS). Microplastics can accumulate across all tropic levels in the marine food web. The purpose of this research was to analyze the stomach and intestinal contents of stranded (Mississippi coast) bottlenose dolphins and sea turtles for the presence of microplastics and commonly found PFAS, PFOS, PFOA, and GenX. Gut contents were digested (10% KOH in 50% MeOH) and then analyzed for microplastics using pyrolysis gas chromatography-mass spectrometry (Pyro-GC-MS), Nile red microscopy, X-ray photo electron spectroscopy (XPS), and Raman spectroscopy. Digested sample filtrate was pre-concentrated using solid-phase extraction (SPE) before PFAS liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The PFOS extraction and analysis had 98.6% recovery when validated with certified pike‒perch fish reference material. The Nile red testing on most samples revealed the presence of microplastics (Table S1). The Pyro-GC-MS results from two samples confirmed the presence of the plasticizer acetamide. The Raman spectroscopy analysis indicated characteristic plastic peaks corresponding to polystyrene in one sample. PFOS (95.5 to 1,934.5 µg/kg) was detected in three dolphin stomach samples. This project is part of a long-term study with the goal of a better understanding of microplastics and PFAS environmental contamination and their impact on bottlenose dolphins and sea turtles.

The dynamism of communication technology adoption, market information and welfare: Evidence from Nile perch (Lates niloticus) fish market, Mwanza, Tanzania

AbstractDespite the growing importance of digital technology in modern society, its adoption in some sectors and regions has been slow. One such sector is fishing in developing countries, where the potential benefits of technology have yet to be fully realized. This study examines the adoption of communication technology among Nile perch fishers on Lake Victoria in Mwanza, Tanzania. Using a Probit model and Ordinary Least Square (OLS) estimations with Robust Standard Errors (OLSR), the study analyzes the impact of technology adoption on fishers' welfare, with a focus on income. The results suggest that the type of mobile phone, fishing experience, and the desire to exploit digital marketing are key factors in technology adoption among fishers. Furthermore, the study finds that technology adoption has a significant positive impact on fishers' welfare, indicating that digitalization can increase market competitiveness, openness, and improve livelihoods. To capitalize on these benefits, the study recommends that the government should support the digitalization of the fishing market and make accurate and timely market information readily available to fishers.

Analisys of lead (Pb) Heavy Metal Content in Climbing Perch Fish (Anabas testudineus) Derived from Rawa Taliwang Lake, West Sumbawa Regency 2021

Rawa Taliwang Lake as an Nature Park in West Sumbawa Regency have an economic value for the fishermens and fish traders from Climbing Perch fish (Anabas testudinesu). Consuming Heavy metals content in climbing perch fish will be damaged human body. This research aims to analysis of lead (Pb) heavy metal content in climbing perch fish (Anabas testudineus) derived from Rawa Taliwang Lake, West Sumbawa Regency 2021. This research was conducted for two months, starting from September - October 2021. Sampling was carried out by purposive sampling method at 2 research stations. Fish samples were taken are 2 fishes from each station using traditional rattan fish trap. The fish species taken were climbing perch fish. The research sample was then analyzed in the West Nusa Tenggara Health, Testing and Calibration Laboratory. The data analysis was carried out by taking muscle tissue from headsnake fish and then analyzing the content of heavy metal in the from lead using AAS (Atomic Absorbtion Spectrophotometry). The measurement result showed that heavy metal content of lead in climbing perch fish from Rawa Taliwang Lake 0,1 mg/kg (ppm) or still under the maximum standard by Food and Drug Supervisory Agency (BPOM) No.5 of 2018 concerning the Maximum Limit of Heavy Metal Contamination in Processed Food which is 0,2 mg/kg.

The Effect of Salt Percentage Difference on the Nutritional Quality of Fermented Climbing Perch (Anabas Testudineus Bloch) Wadi from Central Kalimantan

Wadi is a traditional fish fermentation product in semi-wet whole fish, a bit black (close to the colour of fresh fish), chewy texture with a distinctive aroma of fermented fish salty taste. Wadi is processed by dry salting in a tightly closed container with a high salt concentration (> 25%) at room temperature for 7 days to several months until the aroma of the wadi is formed. This study aims to determine the effect of giving different salt levels to the nutrition of fermented climbing perch fish wadi. The design used in this study is a qualitative descriptive method. This study showed that the higher salt content in the body of fish affects increasing levels of ash, carbohydrates and lowering the content of water, protein, and fat.

Determination of some nutrient minerals in the meats of three species of fishes brought from the Blue Nile and the White Nile, Sudan

Various fish species are found in fish-markets that trigger the need to evaluate the quality of various fish meat products to answer the consumer needs. This study evaluated some mineral elements in the meats of Baiad (B), Tilapia (T) and Nile Perch (NP) fish species. These fish species were brought from the fish market of Wad Medani City (Blue Nile Fishes; BN), and from Kosti fish market (White Nile Fishes; WN). The preparation of fish meat-ashes and the determination of minerals (through Atomic Absorption), were run in the Food Analysis Laboratory, and the Central Laboratory - University of Gezira. The results showed high concentration of Cu element in WN samples was high in B-meat (0.434 mg/L) and in BN sample in T-meat (0.115 mg/L). Mn element in WN samples was high in B-meat (0.282 mg/L) and in BN sample in T-meat (0.292 mg/L). Fe (0.788 mg/L) and Zn (0.950 mg/L) elements were high in NP-meat of WN, while Fe (3.261 mg/L) and Zn (5.123 mg/L) were high in B-meat of BN. WN samples were highly contaminated with Pb which was about 24-folds more than the maximum tolerable limit (0.025 mg/L), while BN samples were still about third that standard. It was cleared that, BN fish samples were relatively rich in Fe and Zn, while WN samples were relatively rich in Cu and Mn elements.The contamination of fish meat of WN with Pb should be seriously studied, and the meat quality of all fish species should be determined.

Socio-Ecological Outcomes of Single-Species Fisheries Management: The Case of Yellow Perch in Lake Erie

This manuscript uses seminal models in fisheries economics to assess the ecosystem effects of policy focused on sustainable management of a single fish stock. Economic models representing fishing decisions under open access and two fisheries management schemes are parameterized using data from the four management units in the Lake Erie Yellow Perch (Persus flavenscens) fishery and linked with an end-to-end ecosystem model representative of the lake food web and spatial species interactions. We find that the sustainable harvest rules from single species economic models result in significant changes to biomass of species in planktivorous, omnivorous, and piscivorous groups in the ecosystem model. These impacts can be traced through the food web back to harvest rules implemented in the management units. Most notably, the biomass of several non-target but also commercially harvested fish species are reduced through Yellow Perch fishing. In some cases, the economic losses to coexisting fisheries exceeds benefits gained from implementing the Yellow Perch management scheme. Our results imply that while an ecosystem-based approach to fisheries management requires weighing trade-offs between multiple fisheries, an ex ante understanding of the whole-system consequences of harvest rules can be critical for developing policy that overall enhances ecological and social wellbeing.

Embryogenesis of climbing perch fish Anabas testudineus Bloch 1792 at incubation temperature of 28°C

Information on the embryonic development of fish is important to understand the early life history of fish, this information is useful for fish breeding, especially in crossbreeding and genetic engineering. Therefore, this study aimed to observe the process of embryonic development and the incubation time of climbing perch eggs which were incubated at a temperature of 28 °C. The results showed that the embryonic development of betok fish was divided into six phases, namely the cleavage phase (3 hours and 5 minutes), morula (4 hours and 30 minutes), blastula (5 hours, and 40 minutes), gastrula (8 hours, and 47 minutes), organogenesis (15 hours, and 39 minutes) and hatched. At an incubation temperature of 28 °C, the climbing perch fish eggs hatched 18 hours and 38 minutes after fertilization.Introduction

STUDY ON GROWTH PERFORMANCE, PRODUCTION, AND RETURN OF VIETNAMESE KOI (Anabas testudineus) FOR SOCIO-ECONOMIC UPLIFTMENT OF RURAL YOUTH IN MANIPUR, INDIA

The climbing perch fish Anabas testudineus, locally known as Ukabi, is one of the important freshwater small indigenous fish of Manipur. It is very popular in the state for its delicious taste and flavor. A study was carried out in nine experimental ponds (each size 0.25 ha) to assess survival rate, specific growth rate, absolute growth, production, and benefit-cost ratio of climbing perch (Anabas testudineus) for four months period during the year 2020. The experiment consists of three treatments T1 (P1& P2- stocking density with 80000 nos. fry/ha), T2 (P3 & P4 stocking density with 100000 nos. fry/ha), and T3 (P5 & P6 stocking density with 120000 nos. fry/ha). Water quality parameters of the test ponds were within the normal range for fish culture. As compared to T2 and T3, T1 was significantly higher in the specific growth rate (5.021±0.001%), absolute growth (113.25±0.18 g), production (1709.4±1.97 kg/0.25 ha), and benefit-cost ratio (3.28±0.19). Therefore, the present study was very important for the proper stocking density of its culture in the Manipur and NE region. It will help in the commercialization of its technique in maximization of production and income for the socio-economic upliftment of rural youth in the state.

Genome-wide DNA methylation profiles provide insight into epigenetic regulation of red and white muscle development in Chinese perch Siniperca chuatsi.

Fish skeletal muscles are composed of spatially well-separated fiber types, namely, red and white muscles with different physiological functions and metabolism. To compare the DNA methylation profiles of the two types of muscle tissues and identify potential candidate genes for the muscle growth and development under epigenetic regulation, genome-wide DNA methylation of the red and white muscle in Chinese perch Siniperca chuatsi were comparatively analyzed using bisulfate sequencing methods. An average of 0.9 billion 150-bp paired-end reads were obtained, of which 86% were uniquely mapped to the genome. Methylation mostly occurred at CG sites at a ratio of 94.43% in the red muscle and 93.16% in the white muscle. The mean methylation levels at C-sites were 5.95% in red muscle and 5.83% in white muscle, whereas the mean methylation levels of CG, CHG, and CHH were 73.23%, 0.62%, and 0.67% in red muscle, and 71.01%, 0.62%, and 0.67% in white muscle, respectively. A total of 4192 differentially methylated genes (DMGs) were identified significantly enriched in cell signaling pathways related to skeletal muscle differentiation and growth. Various muscle-related genes, including myosin gene isoforms and regulatory factors, are differentially methylated in the promoter region between the red and white muscles. Further analysis of the transcriptional expression of these genes showed that the muscle regulatory factors (myf5, myog, pax3, pax7, and twitst2) and myosin genes (myh10, myh16, myo18a, myo7a, myo9a, and myl3) were differentially expressed between the two kinds of muscles, consistent with the DNA methylation analysis results. ELISA assays confirmed that the level of 5mC in red muscle was significantly higher than in white muscle (P<0.05). The RT-qPCR assays revealed that the expression levels of the three DNA methylation transferase (dnmt) subtypes, dnmt1, dnmt3ab, and dnmt3bb1, were significantly higher in red muscle than in white muscle. The higher DNA methylation levels in the red muscle may result from higher DNA methylation transferase expression in the red muscles. Thus, this study might provide a theoretical foundation to better understand epigenetic regulation in the growth and development of red and white muscles in animals, at least in Chinese perch fish.

Sex identification in immature Eurasian perch ( Perca fluviatilis ) using ultrasonography

One of the keys for an optimal Eurasian perch aquaculture broodstock management is being able to determine the sex of individuals. For Eurasian perch, compared with other methods of sex identification of fish and according to the 3R principle (replacement, reduction and refinement), ultrasonography is a rapid, non-lethal, non-invasive and accurate method. During two successive experiments, we used ultrasound to identify the gender of two immature Eurasian perch broodstock. In the last experiment, females were identified with 98.9% accuracy (n = 180) and males with 98.8% accuracy (n = 92). This method can be very beneficial for perch fish farmers or aquaculture research.

СОВРЕМЕННАЯ ГИДРОМОРФОЛОГИЧЕСКАЯ, ГИДРОБИОЛОГИЧЕСКАЯ ХАРАКТЕРИСТИКА И СОСТОЯНИЕ РЫБНОГО НАСЕЛЕНИЯ ОЗЕР ГАЛИЧСКОЕ И ЧУХЛОМСКОЕ КОСТРОМСКОЙ ОБЛАСТИ

Hydrochemical, hydrobiological and ichthyological studies of the two largest lakes in the Kostroma region - Galichskoye and Chukhlomskoye for the period 2005–19 were carried out. Current state of the fish population in comparison with previous periods was analysed. Area of water bodies was updated according to geographic information systems data for 2017–19. The collection and processing of hydrochemical and hydrobiological samples were carried out according to standard methods. The collection of ichthyological materials was carried out by conventional methods using fry drag, small-mesh seines and fixed nets. The boundaries of the lakes were digitized using Landsat satellite images. The hydrochemical indicators of both lakes are within the limits of fishery standards. The hydrochemical regime of Lake Galichskoye is stable. The rise in the water level of Lake Chukhlomskoye had a positive effect on its hydrochemical regime. It has been established that both investigated lakes are currently, as before, highly productive water bodies. According to the concentration of chlorophyll “a” they have a β-eutrophic status, according to quantitative indicators of phytoplankton development they correspond to a high eutrophic level. According to the quantitative indicators of zooplankton, Lake Galichskoye is a low-forage water body (0.37 g/m3), and Chukhlomskoye is a medium-forage water body (2.12 g/m3). Lake Galichskoye is medium-fodder, and Lake Chukhlomskoye is high-forage lakes for benthofagous fish. According to indicator species of zoobenthos, the water of both lakes is classified as an α-mesosaprobic zone, polluted (quality class IV).&#x0D; The species richness of fish on Lake Galich – 16 species, on Lake Chukhloma – 12 species, ichthyomass – 221.9 and 176.5 kg/ha, respectively. It was noted that in the reservoirs over the past two decades, serious changes have occurred in the structure of the fish population. In both lakes, perch fish were replaced by cyprinids, which is associated with the process of eutrophication. In Galichskoye Lake, after a sharp decrease in fishing load since 2005, there has been a significant increase in the number of small-sized fish species caused a corresponding increase in stocks of predatory species (pike and pike perch). In the Lake Chukhlomskoye, the ecological niche of the crucian was occupied by the bream, which was acclimatized in the reservoir almost a century ago. It was determined that during the growing season the average area of Lake Galichskoye is 7124.3 ± 57.5 hectares, of Lake Chukhlomskoye – 4862.7 ± 14.7 hectares.

Fast and efficient Rmap assembly using the Bi-labelled de Bruijn graph

Genome wide optical maps are high resolution restriction maps that give a unique numeric representation to a genome. They are produced by assembling hundreds of thousands of single molecule optical maps, which are called Rmaps. Unfortunately, there are very few choices for assembling Rmap data. There exists only one publicly-available non-proprietary method for assembly and one proprietary software that is available via an executable. Furthermore, the publicly-available method, by Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006), follows the overlap-layout-consensus (OLC) paradigm, and therefore, is unable to scale for relatively large genomes. The algorithm behind the proprietary method, Bionano Genomics’ Solve, is largely unknown. In this paper, we extend the definition of bi-labels in the paired de Bruijn graph to the context of optical mapping data, and present the first de Bruijn graph based method for Rmap assembly. We implement our approach, which we refer to as rmapper, and compare its performance against the assembler of Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006) and Solve by Bionano Genomics on data from three genomes: E. coli, human, and climbing perch fish (Anabas Testudineus). Our method was able to successfully run on all three genomes. The method of Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006) only successfully ran on E. coli. Moreover, on the human genome rmapper was at least 130 times faster than Bionano Solve, used five times less memory and produced the highest genome fraction with zero mis-assemblies. Our software, rmapper is written in C++ and is publicly available under GNU General Public License at https://github.com/kingufl/Rmapper.