Fish Distribution Research Articles

The vertical distribution of fish on two offshore oil platforms

Knowledge of platform ecology is necessary to best inform decommissioning practice. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however, the utility of this video for ecological assessments remains unclear. Archival ROV video surveys at the Wandoo oil platforms on Australia’s North West Shelf was evaluated for its utility, with only 4.9% of imagery usable for standardised ecological studies. Based on the subset of usable ROV video, the influence of depth and structural complexity on attributes of the fish assemblage on the Wandoo oil platforms was examined. Vertical ROV transects on three vertical shafts on the Wandoo platforms were stratified into 10 m depth strata from 0 to 50 m, with 111 fish taxa from 25 families identified and counted across all depth strata. At both platforms, taxonomic richness and abundance was significantly highest in shallow regions and declined with depth. Small reef fish were predominantly associated with structurally complex habitat in shallow regions (<22 m), whilst large demersal species dominated below 32 m. Future decommissioning policy in Australia should consider the vertical fish distributions and the importance of shallow sections of platforms. Finally, the dearth of usable video was due to the haphazard method of collection and it is recommended that future surveys should be conducted according to scientific standards to ensure greater utility of the video for both industry use and scientific research.

Investment Review in Marine Fish Distribution, Baleendah Sub-District, Bandung District, Indonesia: A Case Study

The stable availability of fish as a crucial source of affordable animal protein with commendable nutritional content, contributing significantly to quality protein intake. To provide and ensure a steady supply of raw materials, a marine fish distributor in Baleendah Sub-district, Bandung Regency, is imperative. This distributor, functioning as a fish container (cold storage), acts as a crucial link between major marine fish producers and local fish processing farmers. During abundant fish seasons, the distributor collects fish, supporting prices during limited stock periods. This strategic intervention ensures the continuity of activities for salt-boiled fish processing farmers in Bandung Regency.The key objectives in establishing a marine fish distributor in Baleendah Sub-district, Bandung Regency, include optimizing the operation of distribution facilities and infrastructure. This optimization ensures a consistent supply of raw materials, reducing price fluctuations and ultimately lowering the production cost of processed fish. For the marine fish distribution company to operate sustainably, controlling fixed and variable expenses is crucial. Distributors of marine fish have total fixed and variable costs of IDR 271,950,000. The net result is calculated by deducting the whole fixed and variable costs from the revenue, which comes to IDR 688,050,000. The calculated Revenue/Cost (R/C) Ratio of 3.542 suggests a positive equilibrium between revenue and expenses. This ratio is a crucial financial indicator that shows profitability potential. Furthermore, the payback period—which is projected to be 0.46 years—indicates the amount of time needed to recoup the initial expenditure in relation to the net benefit that is delivered.

Substrate Characteristics Determine the Distribution and Abundance of Reef and Reef-Associated Fish: A Comprehensive Study in Protected and Non-protected Coral Ecosystems of Sri Lanka

Substrate Characteristics Determine the Distribution and Abundance of Reef and Reef-Associated Fish: A Comprehensive Study in Protected and Non-protected Coral Ecosystems of Sri Lanka

Integrating spatial stream network models and environmental DNA to estimate current and future distributions of nonnative Smallmouth Bass

AbstractObjectiveClimate change is fueling the rapid range expansion of invasive species in freshwater ecosystems. This has led to mounting calls from natural resource managers for more robust predictions of invasive species distributions to anticipate threats to species of concern and implement proactive conservation and restoration actions. Here, we applied recent advances in fish sampling and statistical modeling in river networks to estimate the current and future watershed‐scale spatial distribution of nonnative Smallmouth Bass Micropterus dolomieu.MethodsWe integrated a spatial stream network (SSN) model of stream temperature, landscape environmental covariates, and Smallmouth Bass occurrence data based on environmental DNA (eDNA) detections to develop an SSN species distribution model (SDM) representing current Smallmouth Bass distributions in the Chehalis River, Washington State, a large coastal river basin of ongoing watershed‐scale restoration. The SDM was informed by spatially intensive eDNA sampling from 135 locations in the main stem and major tributaries. We then applied downscaled climate change projections to the SSN SDM to predict Smallmouth Bass range expansion in the basin by late century.ResultWe identified high levels of spatial autocorrelation at hydrological distances of ≤10 km in our eDNA data set, underscoring the importance of applying an SSN modeling framework. Stream temperature was identified as the most important environmental covariate explaining variability in Smallmouth Bass occurrence. Model predictions estimated that current suitable summer habitat for Smallmouth Bass habitat spans 681 km and is projected to nearly double by late century (1333 km) under a moderate climate change scenario. Current and future suitable habitat for Smallmouth Bass is prevalent in important tributaries for spring Chinook Salmon Oncorhynchus tshawytscha, a species of major conservation concern in the Chehalis River and more broadly along the Pacific coast. In both the main stem and tributaries, the SSN SDM predictions of the upstream leading edges of Smallmouth Bass closely align with (within 4.8 km) edges identified by spatially intensive eDNA sampling.ConclusionOur study highlights the value of integrating SSN models with rapidly growing eDNA data sets for accurate and precise riverine fish distribution estimation. Our application provides crucial insights for anticipating the impacts of shifting invasive species on Pacific salmon Oncorhynchus spp. in a warming world.

Multiscale analysis predicts native species presence based on habitat and nonnative species abundance

AbstractObjectiveThe loss and degradation of aquatic habitat through fragmentation, water extraction, and climate warming contribute to declining native stream fish diversity. In response to these declines, a large‐scale repatriation program was established in Arizona and New Mexico to expand the distribution and abundance of native fishes. This program has had variable success, with imperiled fish populations establishing and persisting in some streams, while other populations failed to establish.MethodsTo identify factors contributing to the success of repatriation, we conducted a study investigating how biotic and abiotic variables affect native fish presence or absence at differing spatial scales throughout the Gila River basin. We conducted fish and habitat surveys in 29 river reaches at three spatial scales: the 1‐km, 0.1‐km, and mesohabitat scale. We used generalized linear models to identify associations among species presence, habitat characteristics, and nonnative species abundance across spatial scales. Logistic regression models were also used to test associations with heterogeneity of habitat characteristics and species presence.ResultModels indicated strong species‐ and scale‐specific responses to these variables. Nonnative abundance was less influential than other habitat variables in predicting the presence of native fish, although the majority of associations that emerged were negative. Further, we were able to identify that water velocity, depth, and substrate size were the most common variables associated with species' presence across all scales and age‐classes, with most species responding positively to elevated velocities and variable responses for depth and substrate size. Response to variation in habitat was species‐specific, with some associations positive and others negative.ConclusionCollectively, the information from this study will help identify locations with a reasonably high likelihood of supporting native fishes and broaden our understanding of species responses to habitat and nonnative species across multiple scales.

Habitat and morphological characteristics affect juvenile mortality in five coral reef damselfishes

The abundance and distribution of demersal fishes rely on larvae successfully settling from the pelagic environment to a benthic habitat and their subsequent survival. With high mortality rates during this life stage, settling to a habitat that maximizes survival is critical. However, relationships between settlement choices and subsequent survival are poorly understood and may vary among species with different habitat preferences. To test this, we focused on five congeneric (Pomacentrus) damselfish species that are known to differ in their habitat choices and explored whether habitat associations at settlement influenced survival. Newly settled individuals were tagged and monitored daily for two weeks to estimate natural mortality rates. Morphological attributes of fish and characteristics of settlement habitats, including depth, rugosity, benthic substrata, and local fish assemblages, were used to predict mortality. We found that some species displayed stronger associations with specific benthic substrata at settlement, but contrary to expectations, these selected habitat characteristics were relatively weak predictors of survivorship. Our survival analysis revealed that the best predictors of survivorship were rugosity (P. adelus and P. amboinensis) and two morphological traits, body depth and ocellus size (P. chrysurus and P. adelus). Interestingly, we found that P. moluccensis that settled in areas of high coverage of mounding coral experienced increased mortality. Of the remaining substrata, analysis showed that instead of associating with habitat characteristics enhancing survivorship, individuals tended not to associate with habitats characteristics that increased mortality (e.g., Turbinaria and sand). This study highlights the species-specific drivers of early post-settlement mortality in coral reef fishes.

Regional variability in remotely sensed data with respect to the distribution of some snapper fishes (Family: Lutjanidae) between the Red Sea and the Arabian Gulf

Geographically dissimilar aquatic ecosystems from similar origin promote our comprehensive understanding of the role of abiotic factors in the distribution of biodiversity from one extreme, and they provide outstanding examples of convergent evolution in biological diversity on the other extreme. A new approach to monitoring and management of fisheries and marine ecosystems is required. Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) concentration are both crucial environmental variables that have significant impacts on marine ecosystems, particularly for fishes and overall aquatic life. These factors play important roles in shaping the health, distribution, behavior, and productivity of marine organisms. In the current study, Modis-aqua daily SST and Chl-a derived data from 2002 to 2022 were loaded into MATLAB, analyzed, and compared between the Arabian Gulf and Red Sea (Egyptian territory). Additionally, the catch of the family Lutjanidae (snapper fish) was recorded in 2002 to determine the distribution of napper fish species and compare production (based on data available from 2002 to 2022) in relation to SST and Chl-a variabilities. According to the current study, Chl-a in the Arabian Gulf showed narrow fluctuations during the winter and spring months, but higher than the Red Sea, and had a significant increase in sea surface temperature (SST) throughout the summer compared to the Red Sea. Spatial and temporal interaction between the means of Chl-a and SST was significantly different (P < 0.01). On the other hand, the results showed that different thermal stresses were experienced by the Arabian Gulf and the Red Sea, as shown by the total positive SST anomaly and by events occurring in different trends. Both the total catch of lutjanid snappers and the species identified by DNA barcoding varied significantly between the two geographical regions. The current work suggests using large-scale, fisheries-independent data to map the main gradients in marine fish community and species abundance and forecast their future distribution in connection to climate change.

Use of Hydroacoustic Methods to Assess Ecological Status Based on Fish: A Case Study of Lake Dejguny (Poland)

The idea of the article was to verify the thesis that acoustic studies of ichthyofauna in lakes provide sufficient information to determine the necessity (or lack thereof) of carrying out a full procedure for assessing the ecological status based on fish. The manuscript compares acoustic data collected in 2008 and 2021 in Lake Dejguny (Poland) as a result of acquisition carried out with the same EY-500 echosounder, on the same routes (transects), and the echogram analyses were carried out using software dedicated to this echosounder. Target strength (TS) distribution was determined in the lake and in individual water layers with a thickness of 2 m, as well as, using the mapping method, changes in the distribution of fish in selected water layers. Large changes in TS distribution in the vertical profile were demonstrated between both years of the study, as well as a clear reduction in the space available for fish in waters below 24 m in 2021, which was associated with a reduction in the concentration of dissolved oxygen below this depth to a value lower than 2.5 mg L−1. It was suggested that it could be possible to develop a simple index enabling the assessment of changes in fish structure, based, similarly to the Large Fish Index, on the ratio of the number of large fish to small fish. The obtained results confirmed that the proposed methods of acoustic data analysis can be the basis for the decision on the necessity (or lack thereof) of conducting an assessment using the Polish national LFI-EN method based on the results of one-off fishing with Nordic multimesh gillnets.

FISHERIES ECONOMICS-A LITERATURE REVIEW

Fisheries economics refers to the study of economic activities related to the management, production, and distribution of fishery resources. It involves analysing the economic aspects of fishing, aquaculture, and the overall seafood industry. This field explores topics such as resource allocation, market dynamics, policy implications, and sustainability within the context of fisheries and aquatic ecosystems. Fisheries economics refers to the branch of economics that focuses on the economic aspects of the fishing industry. It involves the study of the production, distribution, and consumption of fish and seafood, considering factors such as market dynamics, resource management, trade, and policy implications. The goal is to understand and analyse the economic behaviour and decision-making within the fisheries sector to promote sustainable practices and efficient resource utilization. Fisheries economics is a field of study that focuses on the economic aspects of fisheries and aquaculture. It involves analysing the allocation of resources, production, distribution, and consumption of fishery-related goods and services. This discipline examines the economic behaviour of individuals, businesses, and governments within the context of fisheries management, sustainability, and the impact of policies on the fishing industry.

Larval Fish Assemblages in Coastal Waters of Bangladesh: Spatial and Seasonal Dynamics

The distribution of fish larvae in estuaries is crucial for comprehending the functioning of these ecosystems and their role as nursery grounds for marine fish species. Data regarding larval fish assemblages in the coastal waters of Bangladesh are currently scarce. This study examines the spatial and seasonal dynamics of larval fish communities in these waters using a two-year sampling effort with a bongo net. This study investigates the diversity, abundance, and distribution of larval fishes at four sites (Bakkhali River Estuary, Moheshkhalipara, Naf River Estuary, and Rezu Khal Estuary) on the southeastern coast of Bangladesh. A total of 10,387 fish larvae representing 25 families were identified. Clupeidae (42.9%), Engraulidae (35.5%), Ambassidae (10.1%), Myctophidae (2.1%), and Gobiidae (1.9%) were the five most dominant families based on the larval catch composition. Marked seasonal differences in the larval fish abundance were observed. However, these differences were not observed when comparing the four sampled sites. Additionally, the correlation between environmental variables and the larval abundance indicated that salinity negatively influences (p &lt; 0.001) the larval fish abundance. This is the first comprehensive investigation of larval fish assemblages in the coastal waters of Bangladesh. The findings of this study enhance our understanding of the nursery habitat requirements for the early development stages of both migratory and resident species in subtropical coastal waters, providing valuable information for potential applications in management and conservation efforts.

Policy-oriented adaptation strategies for artisanal marine fisheries under climate and non-climate stressors in San Andres de Tumaco, Nariño, Colombia

Climate and non-climate stressors significantly impact artisanal fishing in San Andrés de Tumaco, Nariño, Colombia, a crucial activity for local food security and employment. Our study aimed to prioritize these stressors on artisanal Fisheries Economic Units (FEUs) and propose policy-oriented adaptation strategies. We adopted an integrated approach, using diverse evidence sources and techniques such as complex network theory and Multi-Criteria Decision Analysis. Key challenges identified include reduced fish catch, abnormal climatic conditions, and changes in fish distribution. The community prioritizes educational, counseling, cultural, and behavioral adaptation measures. Crucial policy-oriented strategies encompass researching fish species' vulnerability to climatic changes, predicting commercial fish distribution considering climatic shifts, and developing a WebGIS for accessible regional climatic information; strategies that are consequently aligned with the Integral Policy for the Development of Sustainable Fisheries in Colombia. Our integrated approach assists decision-making, fostering adaptive capacity within these communities. It underscores the need for policy-driven, locally-sensitive, and strategic action to ensure the long-term resilience of artisanal fisheries against climate change and non-climate stressors.

Diversity of potential and endemic freshwater fishes in Aceh Tamiang

The inventory of fish species is required in developing a fisheries control plan, knowing the fish distribution and the potential of fishes as a basis for water spatial planning. This research aims to evaluate the fish diversity of freshwater fishes in Aceh Tamiang. An explorative study was conducted to investigate freshwater fishes in rivers, reservoirs, and other lotic and lentic ecosystems. Specimens were catched using fishing net, gill net and fish trap. The sampling locations were spread over 10 villages and data were collected from July to August 2023. The water quality parameters observed were temperature, pH, DO and brightness. This study reported a total of 26 species belonging to 11 families including: Cyprinidae, Osphronemidae, Cichlidae, Channidae, Synbranchidae, Clariidae, Zenachopteridae, Bagridae, Anabantidae, Nandidae, and Eleotridae. Whereas Cyprinidae and Osphronemidae are the most dominant families found. Morphometric of body weight varied from 0.6 to 156 g and total length 4.6 to 23.6 cm. The factor condition ranged of 0.26 to 7.95. This study showed the diversities of fishes in Aceh Tamiang which may be important for fisheries management. Furthermore, it serves as a basis for future efforts in domesticating freshwater fish in Aceh.

An individual-based model to predict the spatial distribution of northern pike, European perch and pikeperch from habitat use in a reservoir subject to water level fluctuations

Reservoirs are subject to artificial water level fluctuations leading to a degradation of the littoral habitats. This often results in reduced productivity and biological diversity, particularly for fish. The development of predictive tools of fish population dynamics linked to habitat characteristics can help to optimize management actions such as habitat restoration. We developed a spatially explicit individual-based model, the 3Plake model, which predicts the spatial distribution of three fish species, northern pike, European perch and pikeperch, over seasons and diel cycles according to their habitat use. The model was calibrated with an accurate description of habitat and high spatial and temporal resolution data of fish movements in a French reservoir. The model calibration is only based on a species-specific coefficient of habitat selectivity. It was chosen to (i) match the observed and simulated traveled hourly and daily distances and (ii) minimize a metric quantifying the distance between observed and simulated density maps. The 3Plake model correctly simulated the means of traveled distances and the species distributions along the year on the study reservoir. The minimal input required (HSI maps and maximum distance range) allows its easy implementation on other reservoirs and fish species. It could be used to assess the impact of habitat restoration or water level management scenarios on fish distribution.

Comparative Analysis of the Distribution and Composition of Grouper Fish (Family Serranidae) in the Coral Reef Ecosystems of Batanta and Salawati Islands, Raja Ampat

The Coral Reef Ecosystems of Batanta and Salawati Islands, Raja Ampat is a critical habitat for grouper species (Family Serranidae), which play essential roles in coral reef ecosystems. This study assessed the species composition, abundance, and biomass of groupers across 12 sampling sites in the region. Using the Underwater Visual Census (UVC) method, we identified 14 grouper species, with Plectropomus areolatus classified as vulnerable by the IUCN. Our results revealed an average grouper abundance 17.33 ind/350m2 for Batanta and 18.33 ind/350m2 for Salawati. An average biomass the mean biomass 4288.16 gr/350m2 for Batanta and 1881.10 gr/350m2 for Salawati, indicating substantial biomass within the area. Statistical analyses, including the Kruskal-Wallis test and t- tests reveal no significant difference in abundance between the two locations, as indicated by the non-significant p-value (p = 0.87). Correlation analysis demonstrated a very strong positive relationship between grouper abundance and biomass, suggesting that the Anthropogenic activities have not yet significantly impacted the grouper populations in Salawati and Batanta. The study emphasizes the importance of habitat protection and sustainable fisheries management to support grouper populations. Additionally, ongoing monitoring and adaptive management strategies are necessary to ensure the long-term health of grouper populations and the coral reef ecosystems they inhabit.

Spatial distribution of the sport fishing in the state of Amazonas, northern Brazil.

The objective of this study was to spatialize sport fishing operations and assess the frequency of the use of the fishing areas in the state of Amazonas by combining the Geographic Information System (GIS) approach and information available in the documents sent to the Instituto de Proteção Ambiental do Amazonas (IPAAM). Information on sport fishing tourism operations was gathered from the IPAAM database and fishing licenses (FLs). Data analysis was conducted utilizing descriptive analysis, and the spatialization of the locations was performed using Q-GIS software. From 2002 to August 2021, 163 requests for FLs were made. There was a decrease in the amount of first time FL requests, with a peak in 2018 and 2019, N=17 and N=18, respectively. The activity is conducted in 24 municipalities, with Barcelos (31.36%) and Presidente Figueiredo (17.75%) being the most popular. At the sub-basin level, sport fishing is notably present in the Negro, Amazonas, Aripuanã, Madeira, Purus and Solimões River basins. Overall, 26.38% of operations take place in conservation areas, specifically in sustainable development reserves (SDRs). Barcelos recorded the largest number of rivers used, with 15 rivers. These results can support future proposals for the sustainable management of fisheries through the zoning of fishing areas in the state of Amazonas.

Assessing the influence of abiotic factors on small pelagic fish distribution across diverse water layers in the Northwest Pacific Ocean through acoustic methods

The Northwest Pacific Ocean is one of the most productive fisheries in the world, with small pelagic fish constituting a substantial portion of its fishery resources. Changes in abiotic factors can affect the distribution of marine fish, but there are limited studies on the relationship between abiotic factors and fish density in a vertical direction. This study used acoustic measurement data collected by the scientific research vessel “Songhang” equipped with a Simrad EK 80 scientific echosounder from June to July 2022, to estimate the small pelagic fish resource density in different water layers from 0 to 200 m. Furthermore, Generalized Additive Models (GAMs) were established for various water layers, combined with remote sensing data such as temperature (Temp), salinity (Sal), net primary productivity (Nppv), as well as latitude (Lat) and longitude (Lon) data, to analyze the influence of abiotic factors on abundance density of small pelagic fish species. The results showed that mean abundance and biomass densities estimated based on the acoustic method were 3.12×105±1.42×106 ind/n mile2 and 5768.39±26224.76 kg/n mile2, respectively. Small pelagic fish resources exhibited a predominant concentration within the 0–50 m layers and displayed a significant accumulation phenomenon near the Kuroshio Extension area in each water layer. The GAMs results indicated that abiotic factors affecting fish density vary across different water layers. Temp and Lon factors appeared in optimal GAMs for all water layers and significantly contributed to fish density. Variations in temperature lead to differences in the vertical distribution of fishery resources. Our results emphasized the necessity of exploring the relationship between abiotic factors and fish density within different water layers. This research can provide scientific support for developing and managing fishery resources in the Northwest Pacific Ocean.

Altitudinal distribution and body condition of migratory fish juveniles Megaleporinus obtusidens (Valenciennes) and Salminus brasiliensis (Cuvier) in the main channel of the Uruguay River, Southern Brazil.

In this study, we analyzed the altitudinal distribution and body condition of the juvenile migratory fish Megaleporinus obtusidens and Salminus brasiliensis in the Uruguay River, a South American subtropical river. We used the presence/absence data and condition factor (K) of juveniles as indicators to try to characterize some recruitment patterns of migratory fish in the main channel of the Uruguay River. Gillnet sampling was conducted during two reproductive years, 2015-2016 and 2016-2017 (November and March of each reproductive year), in three Uruguay River stretches at different levels of altitude. The nets remained in the water for 10-12 hours per night or day for 10 days during each field trip (NOV-15, MAR-16, NOV-16, and MAR-17). The abundance of M. obtusidens juveniles were similar between the two reproductive years, whereas S. brasiliensis capture was higher during the 2015-2016 reproductive year. The probability of finding M. obtusidens juveniles in the Uruguay River was negatively correlated (p < 0.05) with the altitudinal gradient of the sampling points, as shown by the GLM model. For S. brasiliensis, the logit model indicated a non-significant probabilistic relationship (p > 0.05) between the presence of juveniles of this fish species and the altitude gradient. Regarding the body condition of juveniles, the water quality of the sampling points did not affect the juvenile condition factor for either species; however, a positive relationship (p < 0.05) was found with the water level for both species, even with an adjusted R2 of 0.13 for M. obtusidens and 0.48 to S. brasiliensis. Altitude gradient and water level were factors that may affect the juvenile distribution and body condition of these species, respectively, in the Uruguay River. Therefore, this information can be used in hydropower generation policies to conserve migratory fish populations in the Uruguay River Basin.

Fish diversity and distribution in the Nanling region

Fish diversity and distribution in the Nanling region

Parasites as Indicators of Biotic Interrelations between Fishes and Waterbirds

The paper deals with the structural features of the waterbirds' cenoses, the fish population composition and distribution of metacercariae of trematodes, whose final hosts are waterbirds, in the model shallow lentic ecosystems of the city of Kyiv (Almazne, Martyshev, Verbne lakes and Sovski ponds). The waterbird cenosis was dominated by ichthyophagous (58.5-75.7&amp;#37;) and pantophagous birds (16.4-41.42&amp;#37;). The black-headed gull &lt;i&gt;Chroicocephalus ridibundus&lt;/i&gt; (21.9-56.7&amp;#37;) prevailed in terms of relative abundance everywhere. The ornithocenoses differed in terms of the subdominant species: in the Almazne lake it was &lt;i&gt;Podiceps cristatus&lt;/i&gt;, in the Martyshev Lake - &lt;i&gt;Sterna hirundo &lt;/i&gt;(14.6&amp;#37;), in the Sovski ponds and Verbne Lake - &lt;i&gt;Anas platyrhynchos&lt;/i&gt; (12.8-20.2&amp;#37;). Differences in the coastal ornithocenoses' composition were confirmed by results of the cluster analysis WPGMA (weighted pair-group centroid (median)); distance measure - 1-Pearson &lt;i&gt;r&lt;/i&gt;). The coastal fish population comprised 24 species, including the native fresh-water (15 species), Ponto-Caspian and Mediterranean self-dispersers (4 species), and alien species - distant invaders (5 species). Parasitological studies revealed trematode metacercariae localized in lens (&lt;i&gt;Diplostomum&lt;/i&gt; sp.) and vitreous body (&lt;i&gt;Tylodelphys clavata&lt;/i&gt;) of the eye, ripples (&lt;i&gt;Apatemon gracilis&lt;/i&gt;), and in the integument of the body (&lt;i&gt;Posthodiplostomum cuticola&lt;/i&gt;). The discriminant analysis enabled to reveal significant differences in the species composition and abundance of trematode metacercariae in the water bodies with different structure of the water ornithocenoses (Wilks' Lambda: approx. 0.92235; &lt;i&gt;F&lt;/i&gt;(8, 510) &amp;#61; 2.6293f) - 2.6293; the dispersion analysis showed confidently lower total number of trematode metacercariae in the Almazne Lake (Wilks' Lambda &amp;#61; 0.87377; &lt;i&gt;F&lt;/i&gt;(6, 432) &amp;#61; 5.0253; &lt;i&gt;p&lt;/i&gt;&amp;#60;0.00005).

Post-harvest bacterial contamination of fish, their assessment and control strategies.

Healthy fish populations lead to healthy aquatic ecosystems and it is our responsibility to be a part of the solution. Fish is one of the most favored foods and is suitable for people of all ages. Fish is an essential source of protein, vitamins, and minerals and a source of income for millions of people. Human population growth and climate change are putting a strain on our food system, demanding the development of sustainable services to enhance global food production and its security. Food safety is an intricate problem in both developed and developing countries. Fresh fish is a highly perishable food with a limited life span; as a result, it must be delivered and kept carefully to minimize deterioration and assure safety. Fish spoilage is linked to biochemical changes that occur post-harvest, such as storage and transportation. These modifications can account for fish spoilage by altering the taste, texture, and appearance. Fish harvesting, distribution, and post-harvest handling are all unhygienic, resulting in poor and unpredictable fish quality in the market. Many innovative and effective control measurements of various bacteria in fish have been proposed and evaluated. This review is a systematic approach to investigating post-harvest fish spoilage, its assessment, and control strategies.