Commercial Fish Catch Research Articles

Baseline Study on Microplastic Contamination in Commercial Fish from the Vellar Estuary, South India

Microplastic (MP) contamination has emerged as a serious worldwide issue. Human activity, commercial operations, and fishing are all concentrated around the coast, resulting in high levels of fish MPs contamination. This preliminary investigation aims to examine MP accumulation in commercial fish caught in the Vellar estuary region. Fish samples were collected from the estuary, and MPs in the gills and gastrointestinal tracts of three commercial fish species were analyzed for quantity, type, shape, and color using standard laboratory techniques. MPs particles were found in 2.55-4.35 items per individual fish, with an overall average of 3.2 particles in the gills and 5.5 in the gastrointestinal tract. The majority of the MPs were blue and green fibers with a diameter of 0.5-1 mm. Fragmented pieces of MPs and fibers were abundant in the gut. These findings demonstrated the extent of MPs contamination in Vellar estuary fish tissues, serving as a baseline for MPs loading in the estuary. This study has significant implications for food safety, highlighting the dangers of MPs in fisheries and aquaculture. It also identifies knowledge gaps in the long-term effects of MPs, suggesting a need for further research in this sector.

Evaluation of the Commercial Fish Catch at the Al-Fao Landing Site, Southern Iraq During January to December 2022

Evaluation of the Commercial Fish Catch at the Al-Fao Landing Site, Southern Iraq During January to December 2022

СЦЕНАРНЫЙ ПРОГНОЗ РАЗВИТИЯ СЫРЬЕВОЙ БАЗЫ РЫБОЛОВСТВА И УЛОВОВ РЫБ В АЗОВСКОМ МОРЕ В УСЛОВИЯХ СОКРАЩЕНИЯ ОБЪЕМОВ ПРЕСНОВОДНОГО СТОКА И РОСТА СОЛЕНОСТИ

Background. The reduction in freshwater runoff and the increase in the Azov Sea salinity are accompanied by a drastic transformation of aquatic biocenoses, as well as restructuring of various ecological groups of the ichthyofauna. Abrupt changes in the composition and abundance of fishing targets render traditional approaches to fishing ineffective and dictate the need to develop new kinds of fishery. Relevance. Identification of possible scenarios of the fishery resource development for the next 5–10 years is necessary to ensure the fisheries sustainability in the Azov Sea Basin. The aim of this work is to analyze the dynamics of the composition of commercial fish catches in the Azov Sea in the modern period of the sea salinization and to develop possible status scenarios for the stocks and catches of fishing targets for the next 3–10 years to substantiate fisheries management and regulation. Methods. In the course of developing such scenarios, the data on the actual dynamics and trends in the fishery resource changes during the comparable periods have been used, as well as the data on the ecological valence of the representatives of various ecological groups of fish at different stages of their ontogenesis in terms of their salinity tolerance. Results. 3 main unequally probable scenarios of changes in the abundance and biomass of various ecological groups of fish — primary industrial-scale fishing targets in the Azov Sea — have been developed; the recommendations for adapting the existing fishing practices to the changes in the fishery resources have been given. Conclusion. A further decrease in the commercial importance is predicted for the freshwater fish species, freshwater-spawning anadromous and semi-anadromous fish species, as well as for gobies and Black and Caspian Sea sprat (tyulka). The role of Black Sea migrants — European anchovy, grey mullets, red mullet, Mediterranean horse mackerel, garfish — will be reduced. Marine fish species — acclimatized so-iuy mullet and Black Sea turbot (kalkan) — will become the main fishing targets.

Estimation of the value of unreported and unregulated commercial and recreational fisheries at inland waterbodies: case study on the Kama reservoir (Perm krai)

The results of the possible volume of fish harvetsed annually by unreported and unregulated commercial and recreational fisheries at Kama reservoir for the period of 2011–2021 are presented. Two approaches were used to assess the unaccounted commercial catch. The first method is based on the comparison of official commercial catches with scientific research data collected during the surveys of commercial fisheries on the reservoir. The second approach is based on official statistics on the number of fishing gear used by commercial fisheries and the real CPUE values for fished species. The volume of recreational catches is estimated by the number of anglers per unit area of the reservoir, seasonal dynamics of visits to the reservoir by anglers, and the species structure of anglers catch. We found that the volume of possible average annual unaccounted commercial and recreational fish catch may exceed the official data by 2–2,5 times.

Cracking the challenges of incentivizing avoidance of unwanted catch

AbstractEffective tools, techniques, and strategies to improve commercial fish catches frequently seem to be overlooked or unused. The mixed success of two major approaches to avoiding or reducing unwanted catches, voluntary or mandatory use of more selective gear, and spatiotemporal shifts of effort based on resource distributions, inspired the call for this themed article set (TS). This TS sought to promote deeper consideration of these outcomes by encouraging research to investigate what is required to make alternative, more selective gear, and spatiotemporal avoidance more attractive to fishers. Of the eighteen articles in the TS, seven investigated the behaviour of fishers and applied existing or novel models to deepen understanding of motivations and incentives to change; little overlap among theories was found, and more and deeper consideration of this topic is needed. Five considered aspects of spatiotemporal avoidance; five described technical or other measures. Creative ideas on these topics continue to arise, but understanding of the motivations of fishers to initiate and maintain cooperative behaviours is still rudimentary. One used good, bad, and ugly experiences with policy implementers to promote governance research to crack open the understanding of interactions between policy implementers and policy advisors, and to identify changes needed to facilitate bottom-up initiatives.

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Commercial fish catch in the Iraqi marine waters from December 2018 to December 2019 was investigated. The study is based on three stations: the first station is located at the Shatt Al-Arab estuary, the second represents the area between the Shatt Al-Arab Estuary and open marine waters, and the third is associated with the Iraqi territorial marine waters. The total weight of the catch was 1881 kg, represented by 500, 654, and 727 kg in the first, second and third stations respectively. The third station was the highest with a majority of the family Sciaenidae by 464 kg, while the lowest was the family Scombridae by 0.5 kg. The total number of species included 37 species, belonging to 27 genera, 19 families, and 6 orders, the largest order represented by a high number of species was the Perciformes and the lowest versatile orders were Oreclotiformes, Nemipterideaformes and Scombridaeformes; while the order Scorpaeniformes was found by only one species.

Identifying and quantifying key pressures in a data poor region: Coastal Spatial Planning in Heraklion Prefecture, Greece

Coastal regions are among the most valuable ecosystems due to the socioeconomic and ecological benefits and services they provide. Pressures, leading to multiple adverse effects on coastal habitats, seriously threaten these benefits. Coastal Spatial Planning (CSP) aims to mitigate these pressures in parallel with the E.U. Marine Strategy Framework Directive. A key aspect of ecosystem-based CSP is mapping the spatial distribution of pertinent pressures, and identifying Key Environmental Indicators (KEIs). This objective however, is difficult to achieve in data-poor regions leading to variable sources of uncertainty. Furthermore, a conceptual framework to homogenize spatially explicit data of relevant pressures is lacking. This study proposes a methodology for developing and integrating spatial pressure datasets in a Geographical Information Systems (GIS) environment. This methodology was applied to a case study location in the northern and southern coastal area of Heraklion Prefecture, in Crete (Greece). The pressure datasets, used, were developed from a synthesis of proxy and satellite data, including abrasion, chlorophyll-a, commercial fish catches, invasive species, light pollution, microplastics, noise pollution, ocean acidification and organic load. These nine Potential Environmental Indicators (PEIs) were subjected to Principal Component Analysis (PCA) in order to reduce the number of parameters, and identify their relationships. The shortlisted 7 KEIs were organic load, chlorophyll-a, microplastics, commercial fish catches, and noise pollution, indicating that this methodology can be of management relevance in the initial steps of CSP implementation, especially in data poor areas. The proposed spatial integration of disparate pressure datasets as part of the flowchart presented constitutes a compositional approach to the spatial illustration of pressures in a coastal area. The patterns of KEI connectivity and disturbance highlighted herein through statistical analysis, could provide a feasible, economic and less biased procedure leading to effective marine resource management, also allowing for a regional and European implementation.

Modeling for Scenarios for Stock Recovery of Russian Sturgeon Acipenser gueldenstaedtii in the Sea of Azov in the Absence of Natural Reproduction

—A new model describing the dynamics of sturgeon (Acipenseridae) population unable to recover or ranked as depleted is proposed as a depleted artificially-stocking population (DAP) model. The model composed of two submodels is implemented in the R language. One of the submodels provides the opportunity to adjust the appropriate parameters used in a global model (the rate of natural mortality of a mature fish stock in a population and the artificial reproduction efficiency) with the optimization-based methods, while the second submodel deals with various scenarios for fish stock recovery over the forecast period. Scenarios are characterized by two parameters: the quantity of juvenils released by sturgeon hatcheries and the commercial fish catch decline caused by the illegal fishing practices and the fish catch for science-based targets. The estimates for the pattern of the Russian sturgeon Acipenser gueldenstaedtii in the Sea of Azov indicate that its stock may be recovered to the target level of 10 thousand tons with the baseline and optimistic scenarios by 2037—2048 relative to the artificial reproduction efficiency and the extent of illegal, unreported, and unregulated fishing. With respect to pessimistic scenarios, the stocks are not expected to recover.

Growth and status of Nile tilapia (Oreochromis niloticus L.) stock in Lake Chamo, Ethiopia

AbstractGlobal inland freshwater fisheries support livelihoods for several million people. These important resources, however, are suffering from excessive overfishing as a result of increasing fishing pressures attributable to an increased human population and subsequent demand for food and economic livelihoods. To this end, very little is known about the vital population parameters and stock status of Nile tilapia (Oreochromis niloticus) in Lake Chamo in Ethiopia. Thus, the present study focused on determining the Nile tilapia population parameters and assessing their stock status in Lake Chamo, using length‐frequency and catch‐effort data collected between February 2018 and January 2019 from commercial fish catches from 10 major fish landing sites. The TropFishR software package was used to determine von Bertalanffy growth parameters, and length‐converted catch curve and empirical models were used to calculate mortality parameters. The maximum sustainable yield (MSY) and its corresponding level of effort (f MSY) were determined using the length‐based Thompson & Bell yield prediction model. The growth parameters L ∞, K and Ф′ of the Nile tilapia stock were found to be 59.4‐cm, 0.41/year and 3.16, respectively. The annual rate of total (Z), natural (M) and fishing mortality (F) were estimated to be 2.442, 0.558 and 1.884/year, respectively. The calculated current yield (711 t/year) is lower than the predicted values of MSY (771 t/year). The present level of fishing effort (2564 nets/day) is more than twice higher than the optimum level of fishing effort (1026 nets/day), clearly indicating overfishing of the Nile tilapia stock in the lake. This finding is also substantiated by the high level of exploitation rate (E = 0.771). Thus, a recommendation based on the results of the present study is a 60% reduction in the fishing effort (1538 nets/day), which will also provide a higher fish yield. The results of the present study also are useful facilitate development of appropriate management strategies for the Nile tilapia fishery in Lake Chamo.

ФИТОПЛАНКТОН КАК КОМПОНЕНТ КОРМОВОЙ БАЗЫ МУНОЗЕРА (БАССЕЙН ОНЕЖСКОГО ОЗЕРА)

The paper presents the results of a study of phytoplankton in Lake Munozero during the vegetation period in 2018. The seasonal dynamics of the biomass and abundance of algae in the southern and northwestern reaches experiencing different anthropogenic pressures has been considered. The reservoir stands out among other water bodies of the Republic of Karelia for its chemical and morphometric characteristics. It is characterized by high mineralization (up to 100 mg/l), isolation of the reaches, low color and content of nutrients and organic compounds. There have been identified 147 taxa of the algoflora with a rank lower than the genus, belonging to 9 divisions. The structure of algocenoses in terms of species richness and quantitative development is determined by representatives of centric diatoms, cyanobacter, dinophytes, and chlorococcal greens, which is important for the formation of the fish food base. Average size of phytoplankton during 2018 in the northwestern reach reached 492 thousand cells/l, the average biomass was 0.468 g/m3. The average size of phytoplankton in the southern reach reached 589 thousand kg/l, the average biomass was 0.459 g/m3. The water quality in the northwestern and southern reaches by the value of the saprobic index corresponds to the III class of waters, but the biomass values characterize both parts of the reservoir as oligotrophic. Shannon's index, quantitative and structural characteristics of phytoplankton differ in the northwestern and southern reaches, seasonal dynamics is not typical for phytoplankton of the oligotrophic Karelian lake. According to the data on abundance and biomass of phytoplankton of Lake Munozero the value of commercial fish catch was calculated.

Is the closed fishing season policy effective in curbing catch declines?

Executive Summary. The closed fishing season policy is annually imposed in Davao Gulf to allow the fish stocks to recover and address the declining fish catch. Whether the closed season is effective in reducing catch and effort however, is still not determined. An assessment on the closed fishing season included survey and focus groups in Governor Generoso, Lupon, Davao City, Sta. Maria, Don Marcelino and Malita, as well as catch assessments using data from Philippine Statistics Office (PhilStat), and GPS tracking of willing small-scale fishers. A survey and an in-depth interview was also conducted to determined impacts on the fisheries market chain. Results of the study show that multiple factors contributed to the successful implementation of the closed fishing season in the Davao Gulf. Catch data analyses show that small scale fish catches have increased (municipal fishers) compared to commercial fish catches. Together the results show that the closed fishing season was effective in curbing catch declines for the fisheries. Thus, continuing the implementation of the closed season will contribute to the sustainability of fish stocks in the Davao Gulf. However, providing support and temporary jobs to displaced commercial fishers are needed.

Factors Driving Long Term Declines in Inland Fishery Yields in the Mekong Delta

The Mekong basin’s fisheries are important sources of food, income, and livelihoods for millions of people in six countries. However, fish yields appear to have declined in recent years according to reports from local fishers throughout the basin. It is important to understand the factors driving the decline in fisheries so that they can be adequately managed. We analysed interview data from 1020 fishers in the Mekong Delta in Vietnam in 2014 to identify trends in catch rates and the possible factors driving the trends. Most of the fishers (68–90%) reported that their catch rates had declined over the previous five years, although some fishers stated that their fish catches had remained stable or even increased. They identified eleven factors that they believed contribute to declines in fish catches, among which the use of illegal gears and overfishing were considered most important, with other factors relatively unimportant. Separately, long-term datasets (1995–2016) showed a general decline in commercial fish catches, which was positively correlated with peak water levels (which indicate flood levels), and negatively correlated with the intensification of rice farming, especially where flooding has been prevented to allow a third annual rice crop. Some data suggests that fishing effort has declined significantly in recent years, so an apparent downward trend in catches is not likely to be a result of overfishing as believed by fishers, which suggests that fishers are not aware of or under-rate the significance of hydrological and land-use/landscape changes. Due to the exceptional importance of the Mekong fishery and the interactions with other more dominant sectors, improved data collection is required to quantify changes in fisheries that result from land use and hydrological changes, and to guide planning which would better resolve competing demands for water and land use.

Monitoring of fish diseases in the Magadan region

In such a large region as the Far North-East of Russia, there is still no purposeful ichthyopathological study of fish diseases, which has epizootic and epidemiological significance. The material for the study was commercial fish caught in different seasons of 1995-2021. As a result of the research, individuals of natural populations and in aquaculture with clinical signs of infectious and parasitic diseases were found, and cultures of virulent strains of microorganisms were isolated. According to the results of the parasitological study, larvae of nematodes of the family Anisakidae and plerocercoids of cestodes Diphyllobothriidae, which have important epidemiological and epizootic significance, were registered. Based on long-term ichthyopathological studies, a retrospective review of own data was carried out. The analysis of infectious diseases of mature individuals of anadromous Pacific salmon of the genus Oncorhynchus, as well as long-term parasitological monitoring in a comparative aspect of the invasion of commercial fish by helminths dangerous to human and animal health, is presented.

Fishing as an important source of food in the Arctic and subarctic zones of Yakutia

Abstract The peculiarity of natural conditions of Yakutia plays an important role in the formation of economic activities of its population. A significant number of rivers and lakes are a favorable condition for the development and preservation of traditional fishing. Currently, more than 89% of the commercial fish catch is produced in the lower reaches of the large northern rivers and lakes in the Arctic and subarctic zones of Yakutia. The main part of this catch is whitefish species, which are valued for their fat content, protein content, culinary, and taste qualities. Fish is a valuable food product for the population of Yakutia. This article presents the results of the study on the nutritional value and the content of heavy metals in the Arctic cisco meat. The high content of fat and protein in the studied samples shows that the Arctic cisco meat belongs to high-protein and high-calorie products and has a high biological value. It was found that on average, the level of toxic metals in the Arctic cisco meat does not exceed the norms accepted in Russia for fish products. The data obtained suggest that the content of heavy metals in fish is due to the peculiarities of living conditions and environmental pollution. Over the past decades, the volume of fish production in Yakutia has been declining due to the socioeconomic and climatic factors. Due to the anthropogenic pollution of water in rivers and lakes by oil products and effluents and waste from various sectors of the economy, especially the mining industry, there is a reduction in the fish resources and there is a need to monitor the environmental condition of the fishing reservoirs and the fish food quality.

A Multi-species modelling approach to assess the influence of hydrological regime on commercial fisheries in a tropical river–estuary system

Hydrological regime is the key determinant of fish species diversity and production in the river–estuary system; thereby it influences the catch dynamics of multispecies fisheries of the system. It is of significant importance to quantify the effect of the river hydrological regime on commercial fisheries in the river–estuarysystem, for developing strategic management plans. This article presents an analytical framework to accomplish the same for commercial fisheries of multiple species, including Macrobrachium rosenbergii, Mugil spp., Harpadon neherus, Wallago attu and Tenualosa ilisha, of a tropical river–estuary system. The prime tool of the framework is ‘Dynamic Factor Analysis’, which identifies the common trends in catch, and quantifies the influence of hydrological factors on multiple commercial fisheries. Annual hydrological and multispecies catch data of the Narmada river–estuary system for the period 1991 to 2013 have been used in the present study. The results reveal two significant trends: Trend 1, representing mainly the Tenualosa ilisha catch; and Trend 2, representing commercial fish catches of the remaining species. The annual observable flood level significantly influences the catch of all but Mugil spp. species. The annual sediment load significantly influences the catch of Tenualosa ilisha , Macrobrachium rosenbergii and Harpadon nehereus. This analytical approach has been effective in understanding the common catch trend patterns and the hydrological factors influencing them in the river–estuary system. The results can be used for formulating sustainable management plans for multispecies commercial fisheries in the river–estuary system.

Population dynamics and exploitation patterns of Oreochromis niloticus in Lake Tana, northwest Ethiopia

AbstractOreochromis niloticus is the dominant commercial fish in the Lake Tana region. However, its fishery is progressively declining over time. Little or no updated information exists on the population dynamics and exploitation patterns of the species, which is crucial to guide its sustainable management. Accordingly, the purpose of the present study was to generate essential biological parameters on the growth, mortality and stock status of O. niloticus, using length‐frequency data collected monthly from the commercial fish catches of 1 year (2014–2015). The total mortality coefficient (Z) was derived from the length‐converted catch curve. Biological reference points were predicted from relative yield‐ and biomass‐per‐recruit analyses. The estimated values of the von Bertalanffy growth parameters were L∞ = 44.1 cm, K = 0.44/year, and t0 = −0.34/year, and the growth performance index (Φ′) was 2.93. The total mortality (Z), natural (M) and fishing mortality (F) rates were 2.37, 0.98 and 1.39 per year, respectively. The current fishery exploitation rate of 0.59 exceeds the estimated biological reference points of Emax (0.52), confirming the stock of O. niloticus in the lake is being overexploited above optimum levels. Size indicators of the catches further illustrate 31% of the landed fish are harvested before reaching sexual maturity, with mega‐spawners comprising only 15%. This indicates the stock is suffering from both growth and recruitment overfishing. The logistic selection model indicated 50% of the fish vulnerable to capture was at 18.14 cm TL. The fish exhibited a year‐round recruitment pattern, with a major peak during May and June. Sustainably managing the fishery, therefore, requires increasing the fish size at first capture (Lc) towards Lopt.

SPECIES COMPOSITION OF COMMERCIAL FISH CATCHES IN WATER BODIES OF THE STAVROPOL TERRITORY FOR THE PERIOD OF THE LATE XX – EARLY XXI CENTURIES

Aim. The aim of the study is to analyze the species composition of commercial fish catches in water bodies of the Stavropol Territory for two periods from 1986 to the present.Methods. The first period from 1986 to 2003 is conventionally highlighted and the second period from 2009 to 2017. Data on linear and area characteristics of the territorial objects was obtained using Landsat 8 satellite imagery.Results. In 2017, in the fish industry of the Stavropol Territory, 10.8 thousand tons of marketable fish were produced, which was about 70% of the best production level in 1990. The share of common carp production was 58%, silver carp – 34%, white Amur – 5% , other carp fish species – 3%, trout and sturgeon – 1%. In 2017, 1415 tons of fish seeds were produced bringing the total to 19 million units, which is 4 times less than in 1990. The importance of fish catching in providing the population of the region with fish is not so great in comparison with fish farming. In different periods of the last thirty years, the total annual catch in regional state water bodies (reservoirs) ranged from a maximum of 1065 tons (1990) to a minimum of 82 tons (2016). The average annual catch in all state water bodies for the period 1986 – 2003 amounted to 357 tons; fish productivity was 32 kg, with fluctuations from 2 to 113 kg/ha in eleven water bodies. Over the past 9 years, since 2009, the average annual catch in all state water bodies has decreased and amounted to 285 tons.Conclusion. For the period of 1986-2003, the average annual catch of common carp and silver crucian carp was 94 tons each and 79 tons of silver carp; the total share of these three species in catches was 85%. Over the past 9 years (2009-2017), the total share of these fish in the catches has decreased to 66%. The average annual catch of common carp and silver carps was almost halved, while the catch of less valuable silver crucian carp increased and reached 103 tons.

Commercial Fish Catch as an Index of Lakes Eutrophication in Egypt

Commercial Fish Catch as an Index of Lakes Eutrophication in Egypt

Potential effects of global climate change on fisheries in the Trasimeno Lake (Italy), with special reference to the goldfish Carassius auratus invasion and the endemic southern pike Esox cisalpinus decline

AbstractGlobal climate changes have led to a gradual warming of the planet, resulting in decreased precipitation and rising temperatures in Mediterranean inland waters. In Trasimeno Lake, the largest shallow lake in Italy, some non‐native fish species have probably benefited from these changes as they are thermophilic and characterised by wider habitat preferences. Fish data collected by gillnets and fyke nets between 1956 and 2016, and by electrofishing in 1993 and 2014, were used to analyse changes over time in the fish community in relation to environmental conditions. An explosion in goldfish Carassius auratus (L.), following its introduction in 1988, coupled with water level fluctuations and reduced transparency, contributed to the reduction in commercial fish catch in the lake, and to the decline of the endemic southern pike Esox cisalpinus Bianco & Delmastro, already threatened by reduced spawning habitat and interspecific competition with other non‐native predatory fishes.

К ВОПРОСУ РЕГУЛИРОВАНИЯ РЕЖИМА РЫБОЛОВСТВА В ВОЛГО-КАСПИЙСКОМ БАССЕЙНЕ (АСТРАХАНСКАЯ ОБЛАСТЬ), НА ПРИМЕРЕ СЕВЕРОКАСПИЙСКОЙ ВОБЛЫ

The article shows the assessment of fishing conditions of roach catches (the number of fishing grounds, fishing gears, catches, catches per unit of fishing effort, fishing intensity, etc.) at the main fishery objects of the Volga delta. There has been made the analysis of structure of size and gender composition of roach from commercial and amateur catches. The results have shown a depression of the population with negative dynamics in future. There have been determined main negative factors affecting the state of roach stock: unfavorable hydrological regime, incoordination in terms of commercial and amateur catches, limits of catch and size. In such circumstances the major purpose is to create a fishing regime, when maximum pass of fish spawners to spawning grounds is provided. The article proposes organizing a special regime of fishing roach with the aim to introduce additional limitations to the commercial fish catch, the main point of which is a transition from fine-meshed seines to medium-meshed seines in the day, when the water level in the Astrakhan region achieves an index mark as 350 cm. This measure will allow assuring a maximum pass of roach spawners to spawning grounds. A similar interdiction must be valid for amateur fishing. It should be noted that this interdiction is a provisional measure allowing to preserve and reproduce roach population.