Fisheries Data Research Articles

Sustained Fishing Threatens Globally Protected Species: Insights from Digital Catch and Genomic Data

Small-scale fisheries capture a wide marine biodiversity including highly vulnerable and endangered species. Despite global conservation efforts, at regional scale, strategies to conserve threatened species are often constrained by poor biological information and a paucity of fisheries data to understand the level of threat posed to their populations. In Myanmar, devil and manta rays (mobulids) are caught for meat consumption and export of gill plates. The impact of this exploitation is not fully understood as mobulid rays, especially in this region, have been poorly studied, catch levels are under-reported and the fishery is unregulated. An accurate knowledge of the species composition and catch levels is an important first step to inform potential management and protection strategies for these species. This study is the first to combine digital catch recording alongside genomic tools to analyze mobulid rays caught in the Tanintharyi Region of south Myanmar. Our catch data analyses indicate a sustained catch and decrease in total landings of mobulids from 2016 to 2018 in Tanintharyi. We identified five species of mobulid rays, including the first record of M. tarapacana for Myanmar. Our analyses of population genomics provided evidence of structured populations of M. thurstoni and partial admixture in M. mobular. Our findings are highly valuable 1) contributing to fill the knowledge gap for these threaten species in the region, and 2) as the first documentation of sustained fishing pressure these rays are exposed to, and the species under potential fishing threat in the Tanintharyi Region, a high priority biodiversity hotspot.

Cormorant predation in fyke net fishing: The direct effects of a protected bird on coastal commercial fishing

The population size of great cormorants, Phalacrocorax carbo sinensis, has risen steeply in the Baltic Sea over the past 40 years. The growing population has resulted in polarized conflicts between conservation and coastal fisheries due to the losses cormorants may inflict on fisheries. Mitigation of the conflicts requires objective estimates of true losses to fisheries, but quantitative research on losses has been scarce. We used continuous video-recordings to systematically quantify cormorant visits and their activity at 15 fyke nets during the 2022–2023 breeding and post breeding seasons. More than 2400 h of video footage were recorded, in which cormorants were found for 664 h. We also quantified the frequency of fish injured by birds in coastal fishing catches using data from the EU Fisheries Data Collection Program including data from fyke nets and gill nets. Our results show that cormorants frequently foraged in open, floating fyke nets but relatively rarely in submerged nets, leading to significantly higher losses in the former. Monitoring data from fyke and gill net catches covering the entire Finnish coast revealed that the proportion of bird-injured fish in catches is very modest (0.5 %) but can be considerable in individual catches. Finally, results indicate that cormorant visits and the proportion of injured fish in the catch tend to increase when distance to the nearest cormorant colony decreases. We conclude that the losses caused by birds are generally modest, except in open fyke nets where cormorants may conduct hundreds of dives and catch dozens of fish a day. Our study shows that cormorant depredation is highly variable in time and space, but also partly manageable by selecting gear that conforms to local cormorant pressures. We underline the importance of systematic scientific research when measuring damage caused by cormorants and ask for evidence-based political strategies to mitigate perceived cormorant problems.

A fish community comparison upstream and downstream a high-head dam on the Upper Mississippi River

Abstract Standardized sampling is useful for detecting and monitoring variations in fish communities and the establishment and spread of invasive species. Lock and Dam 19, a high-head dam with a 10- meter hydraulic head, creates the largest impoundment on the Upper Mississippi River. Upstream, Pool 19 is characterized by static water levels and expansive macrophyte beds. Downstream, Pool 20 is characterized by lotic conditions and sparse vegetation. Lock and Dam 19 serves as barrier to upstream migration of fishes, particularly Bigheaded carp (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molotrix). There is limited standardized fisheries data available for Pools 19 and 20, particularly in off-channel areas. In 2013 and 2014, we conducted two years of standardized electrofishing in Pools 19 and 20 to 1) detect a presence of adult or juvenile Bigheaded carp, 2) quantify differences in fish community structure (i.e., relative abundance of species) between Pools 19 and 20 and among strata (i.e., backwater, side channel, main channel, and impounded reaches), and 3) quantify hydrological differences (i.e., water quality variables) between Pools 19 and 20 and among strata. We detected two Bigheaded carp upstream Lock and Dam 19, the first to be documented using a standardized collection method. We used permutational multivariate analysis of variance using distance matrices (veganR package version 2.6-4) to determine that fish community structure differed significantly between pools (P< 0.01) and among strata (P< 0.01), except between main and side channel borders. We determined water quality variables differed significantly between the pools and among strata demonstrating strata proportional differences may drive the fish community differences between Pools 19 and 20. We have demonstrated that expanding standardized sampling efforts to Pools 19 and 20 is important to understand long-term changes in fish assemblages and the effects of Lock and Dam 19 on the ecology of the Upper Mississippi River.

Spatiotemporal Analysis of Light Purse Seine Fishing Vessel Operations in the Arabian High Seas Based on Automatic Identification System Data

Understanding the dynamic spatial distribution and characteristics of fishing activities is crucial for fisheries management and sustainable development. In recent years, small pelagic fish and cephalopods in the Arabian Sea have become new targets for light purse seine fishing; however, there is a lack of publicly available reports. This study uses automatic identification system (AIS) data from January to May and October to December of 2021 to 2022 in the region between 58°–70° E and 10°–22° N to extract spatial distribution information through three methods. The results show that with a spatial resolution of 0.25° × 0.25°, the spatial similarity index between the fishing ground information extracted in 2022 and catch data was consistently above 0.60, reaching 0.76 in March 2021 and 0.79 in November 2022, while the spatial similarity index in March 2022 exceeded 0.71. The spatial distribution of fishing effort and kernel density was similar to that of the fishing grounds, and the fishing intensity information exhibited the highest spatiotemporal similarity with commercial catch data, making it more suitable as a substitute for fishery data. Therefore, effective international cooperation and efficient joint management mechanisms for fishing vessels are needed to enhance the regulatory oversight of fishing vessels in this region. Integrating AIS data with other technological methods is crucial for more effective monitoring and management of fishing vessels. The findings presented in this paper provide both quantitative and qualitative scientific support for resource conservation and sustainable development in the region.

Brazil and regional fisheries management organizations - What is at stake?

This study compares Brazil's participation in two distinct Regional Fisheries Management Organizations (ICCAT and CCAMLR) from the mid-2000s to 2019 to reveal how domestic governance issues such as substitutability and regulatory capture shape its international negotiation strategies. By contrasting Brazil's active fishing role in ICCAT with its conservation-focused stance in CCAMLR, the study demonstrates how varying domestic interests influence the country’s international engagement and sustainability commitments. By analyzing primary and secondary sources, including government documents, international submissions, and reports from non-governmental organizations, this study offers insights into the complexities of fisheries management in Brazil. The findings reveal that Brazil's contributions to and stance on RFMOs are significantly shaped by internal challenges, including governance instability and insufficient fisheries data, which hinder the formulation of coherent and effective international fishery policies. This study highlights the need for improved governance framework, data reliability, and a balanced approach to environmental and economic objectives to enhance the sustainability of fishery management practices. It provides critical perspectives for policymakers, stakeholders, and researchers concerned with advancing sustainable fisheries governance in Brazil and similar global contexts.

Feasibility Analysis for Predicting Indian Ocean Bigeye Tuna (Thunnus obesus) Fishing Grounds Based on Temporal Characteristics of FY-3 Microwave Radiation Imager Data

Efficient and accurate fishery forecasting is of great significance in ensuring the efficiency of fishery operations. This paper proposes a fishery forecasting method using a brightness temperature (TB) time series spatial feature extraction and fusion model. Using Indian Ocean bigeye tuna fishery data from 2009 to 2021 as a reference, this paper discusses the feasibility of fishery forecasting using FY-3 Microwave Radiation Imager (MWRI) Level 1 TB data. For this paper, we designed a deep learning network model for radiometer TB time series feature extraction (TimeTB-FishNet) based on the Convolutional Neural Network (CNN), Gated Recurrent Unit (GRU), and Attention mechanism. After expanding the dimensions of TB features, the model uses them together with spatiotemporal feature factors (year, month, longitude, and latitude) as features. By adding the GRU and Attention to the CNN, the CNN-GRU-Attention model architecture is established and can extract deep time series spatial features from the data to achieve the best results. In the model validation experiments, the TimeTB-FishNet model performed optimally, with a coefficient of determination (R2) of 0.6643. In the generalization experiments, the R2 also reached 0.6261, with a root mean square error (RMSE) of 46.6031 kg/1000 hook. When the sea surface height (SSH) was introduced, the R2 further reached 0.6463, with a lower RMSE of 45.1318 kg/1000 hook. The experimental results show that the proposed method and model are feasible and effective. The proposed model can directly use enhanced radiometer TB data without relying on lagging ocean environmental product data, performing deep temporal and spatial feature extraction for fishery forecasting. This method can provide a reference for the fishing of bigeye tuna in the Indian Ocean.

Identifying community practices in marine benthic data usage in Florida

A significant proportion of Florida's population lives on the coast and is directly impacted by alterations to the coastal zone, weather disasters (e.g., hurricanes, erosion, flooding), or changes to ecosystem services. Data collected in Florida waters (including water quality, habitat health, bathymetry, and fisheries data) are important for the maintenance of coastal waters, communities, and ecosystems. Yet benthic data collected by a variety of stakeholders are often not shared or openly available, with little metadata to ease data reuse, and are often stored in incompatible formats. To assess the needs of government agencies, private companies, academic researchers, and data managers, we conducted a survey and organized an expert focus group to determine the current state of coastal and marine data usage and distribution in Florida. Through the survey, we asked participants to describe the types of data they use or collect, how they use that data, what limitations they encounter with data sharing, how and when they share their data, and what sorts of metadata standards they use in their work. We determined that many data producers and users are unaware of data standards and often do not follow best management practices for data collection and sharing. The sector of activity of the individual respondent (government, academic, non-profit) determined how data users were interacting with or collecting data and what standards they followed when sharing data. Our expert panel largely echoed our findings, with consistent, well-documented, and standardized datasets being the most important components for data integration in projects. To advance accessibility and reusability of benthic data, our project highlights the need for additional training of stakeholders on data standardization, collaboration and integration, which needs to be applied across institutions. A major need that was identified is tools that make data sharing and metadata creation easier and more efficient.

Absence of predator control increases cod extirpation risk in a Northwest Atlantic ecosystem: inference from multispecies modelling

Atlantic cod Gadus morhua in the southern Gulf of St. Lawrence (sGSL) declined to low abundance in the early 1990s and have since failed to recover due to high natural mortality, which has been linked to predation by grey seals Halichoerus grypus. Increased grey seal harvests have been suggested to improve cod survival; however, predicting the response of cod to changes in seal abundance in the sGSL is complicated by a hypothesized triangular food web involving seals, cod, and small pelagic fishes, wherein the pelagic fishes are prey for cod and grey seals, but may also prey on young cod. Grey seals may therefore have an indirect positive effect on pre-recruit cod survival via predation on pelagic fish. Using a multispecies model of intermediate complexity fitted to various scientific and fisheries data, we found that seal predation accounted for the majority of recent cod mortality and that cod will likely be extirpated without a strong and rapid reduction in grey seal abundance. We did not find evidence that reducing grey seal abundance will impair cod recovery by causing large increases in pelagic biomass so long as pelagic fishing mortality continues at historical levels.

Planning for climate change resilience—Collation, update and assessment of Mozambique’s marine fisheries data and management

Planning for climate change resilience—Collation, update and assessment of Mozambique’s marine fisheries data and management

Pressures on Egyptian Red Sea fisheries from the artisan fishers’ perspective

The Egyptian Red Sea (ERS) supports artisanal, commercial and recreational fisheries, managed using a summertime closure, not applied to recreational fishing. Stock status is little known and management options are severely limited. To inform future management, we report the results of a questionnaire survey of artisan fishers from four Red Sea ports, collecting basic socioeconomic and fisheries data: fleet characteristics, self-reported landings, plus attitudes towards current management. Relationships among catches, technical and social categories and categorised attitudes were analysed using ordinal and multinomial logistic regressions. Median income of ERS artisanal fishers was 54% of the mean income from work in rural Egypt in 2020. Almost all respondents reported declining catches (61% blamed “overfishing”) and most were pessimistic (43% expected to remain fishing in 10 years time). The seasonal closure was poorly supported by artisanal fishers: 75% claimed it contributed to declining resources. The timing of the closure, intended to protect spawning fish, aligned with published spawning seasons for some, but not all important species. 66% of fishers identified this mismatch as the reason for policy failure. High dissatisfaction rates risk non-compliance: e.g. 23% of those interviewed switched to ‘recreational’ fishing during the closed season. Most artisan fishers of the ERS are in a precarious economic position, facing a declining resource, under management that few support, with concerns about the long term future for their livelihood. We suggest transition to a participatory approach with data-driven co-management as a long term solution.

Dynamics of the age composition of the red king crab males in the Barents Sea with account of probability molt

The aim of the research was improvement of the algorithm of age determination for red king crab males in the Barents Sea, by taking into account the molting probability.Materials were the data of research surveys and fisheries monitoring obtained in 2001–2022 and combined in 54 data sets, as well tagging data published in open press.As results the previous algorithm which allowed establish the age composition of the red king crab males catches was improved. The parameters of the model of the dependence of the probability of molting on the width of the carapace, which was established earlier according to the tagging data, were changed. The modified model allowed to improve the adequacy of the estimates by reducing the values of the approximation error. Compared to the previous estimates of the age composition, the account of the probable molting history did not lead to a significant revision of the results: all noticeable generations remained the same as before, the time for recording a generation in catches however increased from 10 to 12 years. The parameters of the proposed model are the closest to those for the Kikhchik subpopulation of the red king crab off the Western Kamchatka. The contradiction associated with the discrepancy in the assessment of the maximum age of both the generation and individual specimens is discussed.Practical value. The obtained results can be applied for the red king crab stocks assessment with the help of cohort models.

Marine recreational fishery trends in total catch, catch per unit effort, and release rates in Delaware during 1981–2021

AbstractThe impact of recreational fisheries on marine ecosystems is often overshadowed by commercial fisheries, although recreational fishing harvest can be substantial, especially for species that are either overfished or experiencing overfishing. Delaware is a small coastal state with ~1,000,000 residents and nearly 272,000 resident and non‐resident anglers. We used publicly available data for Delaware's recreational fisheries during 1981–2021 to determine the nine most caught fish species and to evaluate trends in total numbers caught, harvested, released, and catch per unit effort (CPUE). The top nine most frequently captured fish by recreational anglers were Summer Flounder (Paralichthys dentatus), Atlantic Croaker (Micropogonias undulatus), Bluefish (Pomatomus saltatrix), Black Sea Bass (Centropristis striata), Weakfish (Cynoscion regalis), White Perch (Morone americana), Tautog (Tautoga onitis), Striped Bass (Morone saxatilis), and Spot (Leiostomus xanthurus). The proportion of fish released increased through time for all nine species, suggesting that the recreational fishery in Delaware is transitioning from a harvest‐oriented to a catch‐and‐release‐oriented fishery. Observations of higher release rates in recreational fisheries of Delaware are consistent with the findings elsewhere in the world for freshwater and marine systems.

Optimising the review of electronic monitoring information for management of commercial fisheries

Electronic monitoring (EM) systems incorporating cameras and other devices can collect a broad range of data to support fisheries management. We reviewed the data collection capabilities of EM and considered approaches to increasing efficiency, including cost effectiveness, of EM review. EM can provide information on catch, effort, catch handling, bycatch mitigation, fishing gear and operational data, which are relevant for fisheries management including by Regional Fisheries Management Organisations (RFMOs). Methods to increase efficiency and decrease costs of EM review apply from the programme design phase, through data collection and review. At review, costs may be reduced by sampling imagery optimally to meet monitoring objectives. Considering RFMOs as users of EM-collected information, we applied EMoptim, an open-source simulation model developed in R that estimates the amount of EM review necessary to meet one or more user-specified monitoring objectives. EMoptim uses stratification to increase review efficiency and incorporates a function to explore review costs against the monitoring objectives set. We evaluated the amount of EM review needed to estimate catch with specified precision, using fishery data available from the Western and Central Pacific Fisheries Commission. Model outputs show that EM review requirements increase as catch frequency decreases, dispersion of catch events increases, and when more precise catch estimates are required. Geographical stratification reduced the amount of review required for more commonly caught species and when catch events were focused in a limited area. Optimising review rates across multiple monitoring objectives was most effective for more commonly caught species. We highlight opportunities for future use and development of this prototype modelling package.

Global fishing patterns amplify human exposures to methylmercury

Global pollution has exacerbated accumulation of toxicants like methylmercury (MeHg) in seafood. Human exposure to MeHg has been associated with long-term neurodevelopmental delays and impaired cardiovascular health, while many micronutrients in seafood are beneficial to health. The largest MeHg exposure source for many general populations originates from marine fish that are harvested from the global ocean and sold in the commercial seafood market. Here, we use high-resolution catch data for global fisheries and an empirically constrained spatial model for seafood MeHg to examine the spatial origins and magnitudes of MeHg extracted from the ocean. Results suggest that tropical and subtropical fisheries account for >70% of the MeHg extracted from the ocean because they are the major fishing grounds for large pelagic fishes and the natural biogeochemistry in this region facilitates seawater MeHg production. Compounding this issue, micronutrients (selenium and omega-3 fatty acids) are lowest in seafood harvested from warm, low-latitude regions and may be further depleted by future ocean warming. Our results imply that extensive harvests of large pelagic species by industrial fisheries, particularly in the tropics, drive global public health concerns related to MeHg exposure. We estimate that 84 to 99% of subsistence fishing entities globally likely exceed MeHg exposure thresholds based on typical rates of subsistence fish consumption. Results highlight the need for both stringent controls on global pollution and better accounting for human nutrition in fishing choices.

Revisiting Fishery Sustainability Targets

Density-dependent population dynamic models strongly influence many of the world’s most important harvest policies. Nearly all classic models (e.g. Beverton-Holt and Ricker) recommend that managers maintain a population size of roughly 40–50 percent of carrying capacity to maximize sustainable harvest, no matter the species’ population growth rate. Such insights are the foundational logic behind most sustainability targets and biomass reference points for fisheries. However, a simple, less-commonly used model, called the Hockey-Stick model, yields very different recommendations. We show that the optimal population size to maintain in this model, as a proportion of carrying capacity, is one over the population growth rate. This leads to more conservative optimal harvest policies for slow-growing species, compared to other models, if all models use the same growth rate and carrying capacity values. However, parameters typically are not fixed; they are estimated after model-fitting. If the Hockey-Stick model leads to lower estimates of carrying capacity than other models, then the Hockey-Stick policy could yield lower absolute population size targets in practice. Therefore, to better understand the population size targets that may be recommended across real fisheries, we fit the Hockey-Stick, Ricker and Beverton-Holt models to population time series data across 284 fished species from the RAM Stock Assessment database. We found that the Hockey-Stick model usually recommended fisheries maintain population sizes higher than all other models (in 69–81% of the data sets). Furthermore, in 77% of the datasets, the Hockey-Stick model recommended an optimal population target even higher than 60% of carrying capacity (a widely used target, thought to be conservative). However, there was considerable uncertainty in the model fitting. While Beverton-Holt fit several of the data sets best, Hockey-Stick also frequently fit similarly well. In general, the best-fitting model rarely had overwhelming support (a model probability of greater than 95% was achieved in less than five percent of the datasets). A computational experiment, where time series data were simulated from all three models, revealed that Beverton-Holt often fit best even when it was not the true model, suggesting that fisheries data are likely too small and too noisy to resolve uncertainties in the functional forms of density-dependent growth. Therefore, sustainability targets may warrant revisiting, especially for slow-growing species.

Status of monitoring and evaluation of Tonga’s Special Management Area program

Tonga’s Special Management Areas (SMAs) have been widely supported by the people of Tonga as a successful approach to the comanagement of their fisheries and marine resources. However, due to the dominant focus on expansion of the program over recent years, challenges remain for the effective and consistent monitoring and evaluation needed to understand program impacts. This review compiles all known ecological, fisheries, and socio-economic monitoring and evaluation reports related to Tonga’s Special Management Areas from 2010 onwards. A total of 25 projects with available reports were identified, with most examining ecological (42%) and socio-economic (42%) aspects of SMAs, whereas reporting on SMA fisheries data (e.g. catch) was limited to five available projects. Most studies also represented ‘baseline’ ecological and socio-economic surveys of SMAs during implementation. Only three studies have assessed the ecological impact of SMAs post intervention, and only one of these incorporated ‘follow-up’ surveys at a second time point. Among these, impacts remain mixed, with some SMAs resulting in larger and more abundant fish, but others showing no impact. Other monitoring challenges include no gender disaggregation of data, no monitoring of gleaning, haphazard monitoring by communities, and general concerns of cost, fit for purpose, and overinvestment. Although the limited available ecological data indicates that SMAs can increase fish size and abundance in some cases, rationalised, more efficient, and targeted monitoring is required to better understand and strengthen the functioning of SMAs and inform community and government management decisions.

Catch and characteristics of Decapterus sp. fishing areas in The Southern Waters of East Java - Bali

Abstract One of the essential potential resources of small pelagic fish to the livelihood of fishermen is Decapterus sp. The purpose of this study was to examine the catch and features of the Decapterus sp fishing region in Indian Ocean waters from East Java to Bali. The fisheries data for Decapterus sp during 2019 - 2021 were provided by Ministry of Maritime Affairs and Fisheries, Republic of Indonesia. The chl-a, and SST data were downloaded from Copernicus Marine Environment Monitoring Service (https://marine.copernicus.eu/). The fisheries and environmental data were then grouped by season. The results showed that the highest catch per unit efforts (CPUE) value occurred during transition 2 season with value of 2.89 followed by west season with value of 2.65. The smallest value of CPUE occurred during transition 1 (1.98). In general, most of Decapterus sp were caught in SST range between 27 – 29°C and chl-a range between 0.1 – 0.3 mg/m3. These results can be used as a basis for management of Decapterus sp especially in southern waters of East Java - Bali.

Advancing artificial intelligence in fisheries requires novel cross-sector collaborations

Abstract Artificial intelligence, or AI, has the potential to dramatically improve our understanding and management of the ocean. For fisheries, these benefits could include greater monitoring coverage at lower costs, improved estimates of catch and bycatch, identification of illegal fishing, and seafood traceability throughout the supply chain. However, fisheries AI innovation and adoption faces substantial barriers from the highly regulated nature of fisheries and the complex overlap of government policies, diverse user needs, and market pressures. We argue that needed advances in fisheries AI require novel collaborations to share data and methods, encourage new and diverse entrants to the field, and increase baseline technical literacy across the global fisheries community. Unlocking fisheries data to power AI, particularly image data, can only be achieved through partnerships across government managers, AI developers, fishers and vessel owners, and technology service providers, which, in turn, requires a common vocabulary for policy and technical concepts. With a greater shared understanding across the field, fisheries AI providers can deliver desired results, and users can have confidence that systems are performing as advertised, ultimately meeting monitoring demand and sustainability goals.

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.

A Study on the Impact of Environmental Factors on Chub Mackerel Scomber japonicus Fishing Grounds Based on a Linear Mixed Model

Chub mackerel (Scomber japonicus) is a commercially important fish species which are widely distributed in the North Pacific. Based on the fishery data from China’s high-sea light-purse seine fishing from 2014 to 2020 and the marine environment factors, a mixed linear model considering the actual spatiotemporal stratification of the catch per unit effort (CPUE) was established to analyze the fixed and random effects of marine environmental factors on the CPUE of chub mackerel and to investigate the relationship between the abundance of chub mackerel resources in the Northwest Pacific and two marine environmental factors: sea surface temperature (SST) and chlorophyll-a concentration (CHL). The results showed that SST had a significant fixed effect on the CPUE. In contrast, the natural logarithm of chlorophyll (logCHL) had no fixed effect on the CPUE. Based on the monthly analysis, random fluctuations were observed in the impact of logCHL on the CPUE. LogCHL and CPUE show a positive correlation during spawning and wintering periods and a negative correlation during the feeding period. The study showed that when fishery sampling data exhibit spatiotemporal stratification, linear mixed models can effectively incorporate both the fixed and random effects of environmental factors on the CPUE of chub mackerel. Linear mixed models can play an important role in analyzing the fluctuations in resource abundance and the mechanisms governing the formation of fishing grounds for chub mackerel in the Northwest Pacific.