Fish Stocks Research Articles

Environmental drivers affecting the status of top commercial fish stocks in the Baltic Sea: review

IntroductionLike in many parts of the world, the Baltic Sea experiences a multitude of processes and stressors that influence fish stock dynamics. This paper compartmentalizes 250 publications that examine the cumulative effects and trade-offs of some of the most significant environmental drivers (temperature change, hypoxia, nutrient enrichment, acidification, low salinity, and food-web dynamics) on the ecology of top commercial fish species in the Baltic Sea (cod, sprat, whiting, herring, flounder, and plaice).MethodsA systematic review method was applied to ensure rigorous coverage of existing literature and to provide a comprehensive synthesis of the current knowledge on the subject.ResultsThe results illustrate the extent of scientific research applicable to commercial fisheries knowledge in the Baltic Sea and identify which pressures have the greatest negative impacts on which stocks. Additionally, the findings demonstrate how well top commercial fish species have adapted to the changing environmental conditions of the Baltic Sea. In doing so, the review illustrates the upcoming challenges and underscores which stocks are likely to dominate in the future and which will face difficulties.DiscussionBy considering ecosystem-based fisheries management, this paper emphasizes the need to account for complex ecosystem interactions beyond single-stock monitoring. With increased natural hazards, top commercial fish species have reacted differently, depending on the region and their adaptive capabilities. In most cases, Clupeidae species have adapted the best to their new surroundings, Pleuronectidae resilience is varied, while Gadidae species are finding the Baltic Sea increasingly challenging.

Stock assessment of rosy barb, Pethia conchonius (Hamilton, 1822) in Dal Lake of Kashmir Himalayas

For management of fish stocks, assessing the various parameters of population dynamics are regarded as being extremely important. Under this backdrop the population dynamics parameters viz. growth, mortality and recruitment of Pethia conchonius, inhabiting the Dal Lake of Kashmir Himalayas were analysed using FiSAT II software. The analysed specimens were collected from five different sites within the lake and exhibited a total weight range of 0.3 to 6.4 g and a total length range of 3.1 to 7.8 cm. The relative condition factor for the fish was reported to be 1.11. The growth parameter i.e., asymptotic length, age at zero length, growth performance index and growth constant were reported to be 10.0 cm, –0.75 years, 1.48 and 0.30 year–1 respectively. The total mortality of 1.49 year–1, consisting of natural mortality of 0.88 year–1 and fishing mortality of 0.61 year–1 was reported. An exploitation rate of 0.41 is suggestive of a less exploited state of the fish. The length at first maturity was found to be higher than the length at first capture, a condition that can disturb the stock, as such the utility of a net with relatively larger mesh size is advisable. The current research on the population dynamics of P. conchonius can be used as the baseline data for its management practices.

Influence of different stocking densities of pearlspot (Etroplus suratensis) on plankton diversity indices of biofilm-based rearing system

Aim: Biofilm-based aquaculture systems, proven cost-effective, reduce the need for expensive supplementary feed. The biofilm acts as a natural planktonic food source for reared organisms. Previous research highlighted the influence of fish stocking density and biomass on plankton diversity in different aquaculture settings, underscoring the significance of these factors in biofilm-based systems. Hence, the present study attempted to understand how varying stocking densities of pearlspot (Etroplus suratensis) influence plankton diversity indices in the biofilm-based aquaculture system. Methodology: The present experiment was designed in 5 Practical Salinity Unit (PSU) brackishwater with soil-bottomed FRP circular (500 L) tanks for 60 days. The sugarcane bagasse was used as a substrate forbiofilm production after fertilization with cow dung, urea, and lime. Fries of pearlspot (4.67 ± 0.04 mm 1.71 ± 0.03 g-1) were stocked at four different stocking densities in triplicates viz T1 (50 nos); T2 (100 nos), T3 (150 nos) and T4 (200 nos) fish fry m-3 in the biofilm-based rearing system. Plankton samples were collected from water and biofilm deposited on the substrate and analyzed for diversity indices. The Shannon Diversity Index, Simpson Diversity Index, Simpson Dominance Index, and Margalef Richness Index were used to compute the plankton diversity indices in different treatments using standard equations. Results: In the current investigation, lower stocking densities with lower fish biomass were associated with significantly higher (P≤0.05) Shannon Diversity Index, Simpson Diversity Index, and Margalef Richness Index in water. In contrast, the Simpson Dominance Index in water showed a significantly lower (P≤0.05) value for treatments with lower fish biomass than for treatments with higher biomass. Interpretation: The values obtained for various diversity indices indicated that a biofilm-rearing system with lower E. suratensis biomass produced more planktonic abundance, evenness, and species richness. Key words: Biofilm, Pearlspot, Plankton diversity, Stocking density

Determining demersal fisheries status in fisheries management arena (FMA) 712 under data limited situation

Abstract Demersal fisheries in FMA 712 have been established since the early 1950’s, industrialization in demersal fisheries was started on 1970’s with the operation of trawl fleets in Java Sea. The exploitation continued until the 1980s when the Trawl Ban regulation was enacted. According to historical statical data from 1980 the number of demersal fishing fleets are still dominating and endangered the sustainability of demersal fish stock in FMA 712. This study presented alternatives approaches to determining demersal fisheries status in FMA 712 using the Bayesian surplus production model (cMSY) and Length-Based Spawning Potential Ratio (LBSPR). The cMSY analysis was conducted using time series production data and known CPUE represent the area in FMA 712 and the LBSPR model was conducted using the life-history parameters and the length frequency data. The results show that current demersal fisheries condition is overexploited, points of estimation of the Biomass condition based on 1980-2022 data: B/BMSY 0,803, F/FMSY 1,75 and MSY 323.000 ton. Additionally, the spawning potential ratio (SPR) of the dominant demersal fish species (Lutjanus malabarius and Portunus pelagicus) was lower than the limit reference point (<0,20), indicating overexploited. This study demonstrates that alternatives approaches could be applied to limited data fisheries and provide useful and robust recommendations.

БОЛЕЗНИ ПРОХОДНЫХ ЛОСОСЁВЫХ РЫБ ПРИ ИСКУССТВЕННОМ ВОСПРОИЗВОДСТВЕ В УСЛОВИЯХ КРАЙНЕГО СЕВЕРА ДАЛЬНЕГО ВОСТОКА

Replenishment of fish stocks by increasing the release of juveniles during artificial fish farming is currently an urgent problem in the Far North of the Far East. In 1995-2003; 2021, an epizootological survey of natural spawning grounds and fish farming enterprises located in the northern part of the Okhotsk Sea basin was conducted: Ola, Arman, Taui, Yana, Iret, Ola experimental production acclimatization base, Armansky, Taui, Yansky salmon hatcheries. The aim is to study bacterial and protozoal diseases of passing salmonids in artificial fish farming. The novelty of the research is that for the first time in the waters of the northern part of the Okhotsk Sea basin, bacterial and parasitic diseases were detected in passing salmon fish in natural reservoirs during anadromous migration and artificial fish farming. In pink salmon, chum salmon, coho salmon, sockeye salmon, Aeromonas hydrophila culture isolated from blood and internal organs turned out to be virulent. Aeromonosis was established for the first time in passing salmon fish of natural populations. As a result of bacteriological studies, Aeromonas hydrophila bacteria were isolated from different batches of fertilized eggs, yolk sac of larvae, ascitic fluid of the abdominal cavity of juveniles. Due to the detection of the invasion of juvenile fish Trichodina truttae and Myxosoma cerebralis, which amounted to 10.0-46.5%, trichodyniosis and myxosomiasis were registered. The ways of transmission of infection to fish farms have been established. Fertilized eggs are infected from producers on spawning rivers during the selection of sexual products. The epizootological situation of aeromonosis, trichodyniosis and myxozomiasis is recognized as unfavorable. The method of diagnosis of bacterial diseases of salmonids at fish-breeding enterprises of the region has been improved.

Genetic Diversity and Population Structure of Amphidromous Goby (Stiphodon semoni) in Western Part of Southern Java Waters

Graphical Abstract Research Highlight The genetic diversity of Stiphodon semoni is high. All populations have high haplotype diversity except for Cimaja. No genetic structure is observed within the populations of semoni. The population of semoni has undergone demographic expansion. Cibareno River has the potential to be a protected area. Abstract Fishing activities negatively impact fish populations, potentially causing a decline in fish stocks. Nevertheless, ensuring diversity and connectivity among populations can mitigate these adverse effects. To evaluate the connectivity of river mouths in the western part of Southern Java waters, we sequenced forty Stiphodon semoni individuals from five populations using mitochondrial cytochrome oxidase subunit 1 as molecular markers. The study revealed that S. semoni populations showed high diversity (0.821), with the population in Cimaja displaying the lowest diversity (0.464). Furthermore, the result of the analysis of molecular variance was a Fst value of 0.0630 with a p-value of 0.22. These results along with the result of the haplotype network indicated no significant genetic differences among these populations. This implies that the river mouths in the western part of Southern Java waters are interconnected. The distribution of mismatches showed a single peak, indicating that the populations have undergone demographic expansion. This information could be valuable for the conservation and management of S. semoni in the western part of the Southern Java waters.

WTO Subsidies Agreement on Fisheries (2022-2024): Agreed Terms and Implications for Indonesia

Indonesia has issued a fisheries subsidy policy to encourage the development of the fishing industry because this sector contributes to national development, but the subsidies applied must be in accordance with the provisions stipulated in the WTO. Indonesia is a member of the WTO and in the last few meetings held by the WTO in which the WTO prohibits subsidies, besides that fisheries subsidies can cause depletion of fish stocks and damage to marine biota. This is not in line with the UN program, namely Sustainable Development related to sustainable fisheries, so the implementation of fisheries subsidy policies can cause problems. the 12th WTO ministerial conference, a draft was drafted, but until now the draft has not been ratified, the draft fisheries subsidies at the WTO specifically regulate fisheries subsidies that are prohibited and exceptions in general. the 13th Ministerial Conference 2024 has not yet concluded negotiations on agricultural and fisheries subsidy issues, which remain key concerns for the conference organizers. Trade or Economic Ministers of the WTO engaged in negotiations are aware of the significant differences in positions among member states, necessitating further time for additional negotiations to be continued by permanent delegations in Geneva. The impact of the draft WTO fisheries subsidy, if successfully ratified, will have a negative impact on Indonesia in terms of the fishery market, fishery resources and employment.

Using blockchain and AI technologies for sustainable, biodiverse, and transparent fisheries of the future

This paper proposes a total fusion of blockchain and AI tech for tomorrow’s viable, rich in diversity and transparent fisheries. It outlines the main goal of tackling overfishing challenges due to lack of transparency and biodiversity depletion in the fisheries sector. With the use of blockchain technology, we can ensure that all fishery products are safely traced from their harvest up to when they get to the market— at the same time, AI algorithms are used in monitoring fish populations and predicting them plus decision-making processes which should be enhanced thus promoting bio-diversity and ensuring sustainability of fish stocks. Results show promise on using both technologies together: improving sustainability plus transparency in fisheries which would promote more fish biodiversity, while others including using an artificial intelligence system have not been confirmed yet by observations. The conclusion underscores the transformative nature of these technologies as having great implications towards fisheries management; this implies that there is a need for future observational studies aimed at validating such other findings.

Decadal changes in the Sea of Marmara indicate degraded ecosystem conditions and unsustainable fisheries

Globally, all marine ecosystems are under pressure by anthropogenic stressors. However, semi-enclosed seas are at a greater risk of degradation due to their limited connectivity to open seas. This leads to a greater accumulation of pollutants and abrupt regime shifts triggered by unsustainable exploitation of living resources, as ecosystems exhibit low degrees of redundancy and more frequent large-scale episodic events such as harmful algal blooms. The Sea of Marmara is a semi-enclosed marine region that has been subjected to various anthropogenic stressors since the 1990s. Recently, local and governmental authorities have employed basin-wide ecosystem management plans to control and manage point and nonpoint (diffuse) sources of pollutants. However, the management of fisheries in relation to the dynamics of the Sea of Marmara food web has attracted less attention from policymakers, even though fisheries exploitation is one of the most significant anthropogenic pressures. In this study, we capitalized on a previous static ecosystem model of the Sea of Marmara by revising and extending it to simulate the changes between 1990 and 2020. We delineated the temporal dynamics and regime shifts in the food web in terms of ecosystem structure and function by using ecological indicators and developed quantitative management advice for its fisheries. The results showed that the ecosystem has experienced three regimes since 1990, with regime shifts occurring with the onset of the 2000s and the mid 2010s. The first regime exhibited high diversity and material cycling, the second regime was characterized by low diversity and increased impact of fisheries, and the third regime culminated in a fished-down food web state. The analysis of fishery dynamics showed that the majority of harvested species were overexploited. We suggest that the implementation of quotas for exploited species should be considered an immediate solution to the unsustainable exploitation of fish stocks and can help restore ecosystem conditions.

Multi-marker DNA metabarcoding for precise species identification in ichthyoplankton samples

Ichthyoplankton monitoring is crucial for stock assessments, offering insights into spawning grounds, stock size, seasons, recruitment, and changes in regional ichthyofauna. This study evaluates the efficiency of multi-marker DNA metabarcoding using mitochondrial cytochrome c oxidase subunit I (COI), 12S rRNA and 16S rRNA gene markers, in comparison to morphology-based methods for fish species identification in ichthyoplankton samples. Two transects with four coastal distance categories were sampled along the southern coast of Portugal, being each sample divided for molecular and morphological analyses. A total of 76 fish species were identified by both approaches, with DNA metabarcoding overperforming morphology—75 versus 11 species-level identifications. Linking species-level DNA identifications with higher taxonomic morphological identifications resolved several uncertainties associated with traditional methods. Multi-marker DNA metabarcoding improved fish species detection by 20–36% compared to using a single marker/amplicon, and identified 38 species in common, reinforcing the validity of our results. PERMANOVA analysis revealed significant differences in species communities based on the primer set employed, transect location, and distance from the coast. Our findings underscore the potential of DNA metabarcoding to assess ichthyoplankton diversity and suggest that its integration into routine surveys could enhance the accuracy and comprehensiveness of fish stock assessments.

MARINE FISHERIES AND ITS IMPACT ON COMMUNITY: AN OVERVIEW

Marine Fishery is the harvesting of fish and other seafood from the ocean for commercial, recreational, and food purposes. Marine fisheries, resources provide animal proteins to billions of people globally. Marine fishery has a vital role in human development and welfare as it provides employment, production, and trade, and has a significant share. In the national economy. There are several types of marine fisheries, which provide food security, livelihoods and economic benefits to millions of people especially the coastal communities. Sustainable fisheries of the world, facing many problems, like overfishing, habitat destruction, and climate change resulted in the depletion of fish stock and threat to the marine ecosystem. To get the long- term benefits and to reduce the pressure on marine fishery, conservation efforts i.e. sustainable fishing, marine protected areas establishment and enhancing aquaculture productivity are essential. Coastal area communities around the world usually depend upon the fishing industry for their food, income, and livelihood. Marine fisheries impacted on the communities in both ways i.e. positively and negatively. Economic and ecological impacts of marine fisheries on communities are significant. To mitigate negative impacts and enhance positive impacts of marine fisheries on the communities, the present project is undertaken to highlight those impacts by gathering the data about marine fisheries and its allied subjects from 1980 - 2024. In the end some suggestions are coated, like fisheries management practices, community-based management, and social responsibility initiatives, for better and sustainable fishery industry of the country.

Resource Availability and Use in Restored, Unmanaged, and Aquaculture Mangrove Ecosystems in Indonesia

Mangrove ecosystems are some of the most productive on our planet but have declined globally by 30–50%. Many species rely on mangrove habitats; thus, their conversion to aquaculture farms has led to noticeable losses in commodities such as wild fish stocks. This study aimed to assess the influence of aquaculture and restoration projects on the ecosystem’s ability to provide resources. We collected data on mangrove vegetation (i.e., biomass, richness, and abundance), soil nutrients (i.e., organic carbon, aluminium, and nitrogen), crab abundance, and fishing pressure at six sites. We set up 15 plots at each site and collected data between May and July 2023. Via generalised linear mixed models, we found that the abundance and richness of crabs was significantly higher in aquaculture plots than in non-aquaculture plots. Aquaculture plots had higher topsoil aluminium, higher topsoil and subsoil nitrogen, and lower topsoil carbon than non-aquaculture sites. Restored sites had less nitrogen in the topsoil than unmanaged sites. The biomass did not change between aquaculture, restored, and unmanaged plots. We found a negative correlation between crab abundance and richness and mangrove diameter at breast height (DBH), suggesting that the species of crabs present preferred areas with propagules for feeding (e.g., Grapsidae crabs). The content of nitrogen in the subsoil was positively correlated with mangrove richness, diversity, and height, suggesting the importance of nitrogen availability for mangrove growth. The content of aluminium in the subsoil was negatively correlated with the content of organic carbon in both the topsoil and subsoil, suggesting the detrimental effect of aluminium on the carbon cycle. Fishing practices were observed at all sites during the data collection period. Despite the lack of significant impact on most vegetation parameters and the limited differences between managed and unmanaged sites, key variables such as soil aluminium, carbon, and nitrogen contents and crab assemblages exhibited high variability, highlighting the complex interactions within mangrove ecosystems.

Predicting weight dispersion in seabass aquaculture using Discrete Event System simulation and Machine Learning modeling

Marine aquaculture, particularly in the Mediterranean region, faces the challenge of minimizing growth dispersion, which has a direct impact on the production cycle, market value and sustainability of the sector. Conventional grading methods are resource intensive and potentially detrimental to fish health. The current study presented an innovative approach in predicting fish weight dispersion in European seabass (Dicentrarchus labrax) aquaculture. Seabass is one of the two major fish species cultivated on the Mediterranean coast, with a fattening cycle of 18–24 months. During this period, several grading operations are carried out to minimize growth dispersion. The intricate feed-fish-water system, characterized by complex interactions among feeding regimes, fish behavior, individual metabolism and environmental factors, is the focus of the study. The comprehensive, five-step methodology addresses this complexity. The process begins with a Discrete Event System (DES) model that simulates the feed-fish-water dynamics, taking into account individual fish metabolism. This is followed by the development of a surrogate machine learning (ML) regressor model, which is trained on DES simulation data to efficiently predict growth distribution. The model is then calibrated and customized for specific fish stocks and production tanks. The preliminary results from 21 tanks in two trials with European seabass (D. labrax) showed the effectiveness of the method. The results from the simulation models achieved a R2 of 99.9 % and a Mean Absolute Percentage Error (MAPE) of 1.1 % for the prediction of mean final weight and a R2 of 90.3 % with a MAPE of 8.1 % for the standard deviation of final weight. In summary, this study represents a significant advance in the planning and management of seabass aquaculture. Given the lack of effective prediction tools in the aquaculture industry, the proposed methodology has the potential to reduce risks and inefficiencies, thus possibly optimizing aquaculture practices by increasing sustainability and profitability.

Effectiveness of textured vegetable protein incorporation for partial fish meat substitution in fish cakes

SummaryExcessive consumption of seafood has resulted in a decline in fish stocks and the destruction of ecosystems worldwide. Textured vegetable proteins (TVPs) can be used in manufacturing fish products, including surimi‐based fish cakes, to prevent these problems. In this study, we aimed to incorporate TVP into fish cakes as an alternative to fish meat (surimi). Fish cake samples containing TVP (0, 5%, 10%, 15% and 20%) were prepared and cooked through boiling or frying. Texture profiles, volatile compounds and consumer acceptance of the fish cake samples were measured. An increase in TVP content enhanced the protein content of the samples, making them more suitable than fish meat is as a protein source. In the fish cake samples, the textural properties, including hardness, springiness, cohesiveness, gumminess and chewiness, increased with increasing TVP content. Analysis of the volatile compounds showed that hexanal and 2‐pentifuran, which are primarily responsible for the grassy or beany flavour of soy, increased with increasing TVP content in fish cakes. The levels of these components were significantly lower in the fried samples than in the boiled samples. Overall, fried fish cakes containing 5% TVP (FST5) exhibited acceptance ratings similar to those of the control. Moreover, FST5 scored the highest in appearance, odour, taste and overall liking. Therefore, fried fish cakes supplemented with 5% TVP were qualitatively similar to fried fish cakes containing 100% fish meat (surimi). We propose the partial substitution of fish meat with alternative products to potentially reduce overfishing.

Performance indicators of the red grouper (Epinephelus morio) fishery along the Yucatan coast, Southeast Mexico

This study assesses the Fishery Performance Indicators (FPI) of the red grouper fishery, currently overexploited, aiming to identify factors for sustainable management and economic growth. Evaluation spans commercial and recreational fishing activities and encompasses output indicators focusing on ecology, economy, and community, through 68 metrics, including measures related to stock abundance, ecosystem impacts (e.g., habitat degradation, bycatch rates), and social aspects (e.g., community participation in management). Input indicators assess enabling conditions such as diseases, water quality, air pollution, biodiversity, etc. Scoring involved reviewing fishery data and information from various sources including scientific literature, technical reports from workshops and meetings, journalistic notes, databases, and unpublished data; with each metric scored according to its specific system. The red grouper fishery exhibits strengths in harvest and community involvement but grapples with stock and ecological concerns. Medium-size fleet perform adequately, yet challenges arise from aging vessels and market fluctuations. Artisanal fleet encounter issues like illegal fishing and economic struggles, while recreational fishing faces stock and ecological worries. Persistent environmental and governance challenges underscore deficiencies in management practices and fishing markets. Enhancing the red grouper fishery requires fair pricing, effective stock management, and sustainability efforts in co-management, fisheries management, and post-harvest processes. Improving gear selectivity is crucial for effective stock management, involving minimizing catches of juvenile red grouper and incidental species. Insufficient bargaining power results in an unfair market and disadvantages for fishermen, leading to losses. To address these issues, it is essential to diversify market channels, stabilize prices, and advocate for fair pricing mechanisms. Empowering fishermen through collective bargaining and regulating credit agreements can ensure fairness. Additionally, policy interventions are necessary to support fishermen and foster a more equitable industry.

Vulnerability Assessment of Commercially Essential Fish Stocks in the Data-Poor Northwest Coast of India

Vulnerability Assessment of Commercially Essential Fish Stocks in the Data-Poor Northwest Coast of India

RETRACTED: Radulescu, V. Environmental Conditions and the Fish Stocks Situation in the Black Sea, between Climate Change, War, and Pollution. Water 2023, 15, 1012

This journal retracts the article “Environmental Conditions and the Fish Stocks Situation in the Black Sea, between Climate Change, War, and Pollution” [...]

Paired comparisons with quiet surface drones show evidence of fish behavioral response to motorized vessels during acoustic surveys in Lake Superior

Acoustic surveys are important for fish stock assessments, but fish responses to survey vessels can bias acoustic estimates. We leveraged quiet uncrewed surface vessels (USVs) to characterize potential bias in acoustic surveys. Five conventional motorized ships overtook USVs from astern over 2 km transects at night in Lake Superior in 2022. We examined the difference in acoustic backscatter, average target depth, and average target strength (TS) between USV and motorized vessels. Although sound level measurements from the motorized vessels sometimes exceeded recommendations for scientific vessels, we did not detect differences in acoustic measures among survey vessels. However, the USVs recorded 2 dB higher acoustic backscatter and TS than motorized vessels, leading to ∼15% higher fish densities with drones when using in situ TS and echo integration. Differences in fish density would increase to 30%–60% if a standard TS value was applied. Target depth did not differ between USVs and motorized ships. These results are consistent with a change in orientation but not depth of insonified fish and limited horizontal avoidance of motorized survey vessels.

Rising temperatures, falling fisheries: causes and consequences of crossing the tipping point in a small-pelagic community

Global change has profound effects on marine species, communities, and ecosystems. Among these impacts, small pelagics have emerged as valuable indicators for detecting regime shifts in fish stocks. They exhibit swift responses to changes in ocean variables, including decreased abundances, accelerated juvenile growth rates, early maturation, and reduced adult sizes in warm waters. However, each pelagic species occupies a unique local ecological niche, that reflects the sum of all environmental conditions. Consequently, their responses to environmental changes manifest in distinct ways. We explore here how global change affects small pelagics in the Madeira Archipelago (NE Atlantic Ocean) at (i) community level, by studying the effects of climate change over a 40-year (1980–2019) period on small pelagic landings, and (ii) population level, by studying the effects on the life-history traits of the two most abundant species, Scomber colias and Trachurus picturatus. Our study demonstrated that anomalies in the Sea Surface Temperature and the North Atlantic Oscillation caused a regime shift within the small pelagic community. Both environmental predictors explained 88.9% of the community landings oscillations. S. colias appears to exhibit a relatively more favorable adaptive response to climate change compared to T. picturatus. Understanding the species-specific ecological responses of small pelagic fish to global change is crucial for effective management and conservation efforts in the face of ongoing environmental scenarios.Graphical abstract

Discriminating the origin of fish from closely related water bodies by combining NMR spectroscopy with statistical analysis and machine learning

Pikeperch, perch and bream are among the most traded and valued fish species in North-Eastern Europe. Therefore, it is necessary to be able to distinguish fish from different lakes and coastal sea regions to ensure a good traceability of products in the fish market and to protect both consumers and fish stocks. Untargeted metabolomics using nuclear magnetic resonance (NMR) spectroscopy is a suitable tool for this purpose. It is an established method for determining various properties of biological and living systems, such as health, origin, type, etc. Statistical methods including principal component analysis (PCA) and linear discriminant analysis (LDA) are typically applied to NMR data to correlate spectra with a particular research question.Herein we examine fish from three closely related water bodies and demonstrate that reliable determination of the water body that a particular fish originates from by traditional statistical analysis (PCA and LDA) of fish NMR spectra is not possible. In contrast, determining the fish species is possible. We proceed to show that machine learning methods perform better and that a combination of statistical analysis (LDA) and random forest (RF), a supervised machine learning technique, allows reliable determination of the originating water body, while being also tolerant to seasonal variations. This is an improvement over prior work, which has dealt with more clearly distinguished origins of fish. Exceptional accuracy was achieved in correctly assigning fish to their origin even in a scenario where two of the water bodies are connected by a river through which the fish are known to migrate. Since determining the origin of fish is important in environmental protection, we recommend following up this approach and using it as the basis of a robust tool for environmental protection and other monitoring purposes.