The Adriatic Sea represents one of the most productive areas of the entire Mediterranean basin, with anchovy ( Engraulis encrasicolus ) being among the main targets of fishery. Two decades (2003-2023) of anchovy Catch Per Unit Effort (CPUE) have been made available through continuous data collection derived from the Fishery Observing System (FOS) and the Adriatic Fishery & Oceanography Observing System infrastructure (AdriFOOS), implemented by CNR-IRBIM. These systems leverage commercial fishing vessels as Ships Of OPportunity (SOOPs) by transforming them into autonomous data-collection units capable of recording geo-referenced catch data (supplied by fishermen through a dedicated interface), along with in-situ environmental information (through sensors installed on the fishing gears). By means of Generalized Additive Models (GAMs), the influence of environmental and anthropogenic drivers on anchovy’s CPUE spatio-temporal distribution in the Adriatic Sea was analysed. Temperature and fishing depth were shown to influence anchovy’s CPUEs. In contrast, vessel characteristics (except for vessel power), as well as latitude, exhibited less clear effects on CPUEs. This study characterized the effect of environmental and fleets’ changes, over space and time, on anchovy’s CPUE in the Adriatic Sea. Furthermore, this approach provides a good example of data collection using commercial fishing vessels, demonstrating the potential of SOOPs to advance the investigation on population dynamics. • Fishery observing systems were employed to collect data on European anchovy CPUEs in the Adriatic Sea. • A 20-year time series of georeferenced catches and environmental parameters was used. • CPUEs spatio-temporal distribution was modelled using Generalized Additive Models. • Environmental and anthropogenic drivers significantly influence anchovy’s CPUE. • Commercial fishing vessels resulted effective in characterizing anchovy’s dynamics.

Anadromous fish travel through estuaries when migrating between their marine growth habitats and their freshwater spawning grounds. In these dynamic transitional environments, strong currents and extreme dissolved oxygen and turbidity levels can result in stressful conditions for fish, impeding longitudinal connectivity. This study examined how estuarine hydro-environmental variables influence the temporal dynamics of spawning migration in threatened European shads ( Alosa alosa and Alosa fallax , undistinguished) across five environmentally contrasted estuaries along the French Atlantic coast. In the first part, focusing on the Loire estuary, catch per unit effort (CPUE) from commercial fisheries were consistent with individual tracking data from a 2011 telemetry study, revealing more intense migration activity during neap tides than during spring tides. Consistently, statistical models (Boosted Regression Trees) built over a longer period (2011-2018) showed higher CPUE under conditions of low turbidity, elevated oxygen saturation, and moderate ebb current velocity. In the second part, the temporal patterns of shad migration and hydro-environmental conditions were compared across estuaries. A fortnightly periodicity (14 to 15 days) was detected in the Loire and Gironde estuaries, in line with the neap-spring tidal cycle. This periodicity was not observed in the Seine, Vilaine and Adour estuaries, where oxygen and turbidity levels were less extreme during spring tides. These findings support the hypothesis that the estuarine turbidity maximum zone can act as a partial barrier to migration during spring tides, thereby structuring the long-term migration dynamics in macrotidal turbid estuaries. • ETM act as a partial barrier during European shads spawning migration • Extreme oxygen and turbidity conditions occur during spring tides • Migration follows a fortnightly cycle (14-15 days) in turbid estuaries

ABSTRACT The dolphinfish (Coryphaena hippurus) is a highly migratory species whose distribution is strongly influenced by oceanographic variability, yet traditional catch-per-unit-effort (CPUE)-based assessments often neglect such dynamics. This study aims to quantify the nonlinear environmental preferences of dolphinfish to improve the accuracy of fisheries forecasts and support sustainable management strategies. To quantify habitat selection mechanisms, we integrated pop-up satellite archival tag (PSAT) tracks from 10 individuals with remote sensing data and oceanographic model outputs (e.g. hybrid coordinate ocean model, HYCOM; and Argo float data) and applied generalized additive models (GAMs) to evaluate the nonlinear relationships among residence times and environmental factors in the northwestern Pacific. Three environmental variables, namely, sea surface temperature (SST), sea surface salinity (SSS), and mixed layer depth (MLD), were identified as the dominant factors driving the residence times of dolphinfish. Our analysis revealed clear ecological thresholds: dolphinfish exhibited the longest residence times at SSTs of 25–27°C, departed rapidly when SSS exceeded ~34.25 PSU, and consistently avoided mixed layers (MLD) between 23 and 53 m. These findings indicate that water mass properties, rather than current dynamics, are the dominant drivers of short-term residency decisions. By defining species-specific ecological windows, this study highlights the value of integrating biologging with remote sensing data to capture fine-scale habitat responses. The results provide a scientific basis for dynamic fishing ground forecasting and adaptive management of dolphinfish fisheries under climate-driven ocean change.

Fisheries around the world serve more than 3.3 billion as a major source of animal protein and about 10 % of worldwide livelihood but almost 35% of the measured fish stocks are currently overexploited based on the Food and Agriculture Organization. This paper will discuss the role of sustainable methods of harvesting and habitat preservation strategies to balance economic development with sustainable conservation of the ecosystem in the long run. The issue that is discussed is the constant trade-off between maximization of revenues in the short-term and the decreasing biological productivity of marine ecosystem, which poses a threat to both the biodiversity and economic stability. The study has adopted a mixed methods design to combine bioeconomic modeling, catch-per-unit-effort (CPUE) and spatial habitat evaluation on three coastal fisheries over 10 years. Scenarios involved the comparison of traditional open access harvesting with regulated systems that involved catch quota systems, seasonal restrictions, selective gear technologies, and marine protected areas (MPA) of 20-30% of important habitats. Economic (net present value, employment rates) and ecological (spawning stock biomass, species diversity index) indices were compared. Findings suggest that application of science based catch limits led to a 28% drop in the rate of stock depletion and a 35% rise in spawning biomass after a period of five years. Varying gear usage reduced bycatch by 22% and MPAs increased adjacent fishery yields by 17% as a result of spill over effects. Regulated fisheries were found to have 14% higher long-term net present value than the open access models, even though it was initially reduced by 8% of the short-term profits. The results indicate that a combination of sustainable harvesting and habitat protection can be used to both improve ecological performance and financial payoffs. Policies that couple conservation incentives and market responses are critical to achieve fisheries productivity, biodiversity conservation and livelihoods of the coastal community in the context of increased global demand.

Abstract Batulicin Fishing Port is one of the fishing ports in South Kalimantan Province where the fish landing is quite good and neatly structured. Male mackerel is one of the economically valuable catches in the port. Batulicin Fishing Port is located in Tanah Bumbu Regency, South Kalimantan Province. The objectives of this study are 1) Analyzing the Catch per Unit Effort (CPUE) value of Male Mackerel landed at Batulicin Fishing Port; 2) Analyzing the value of Maximum Sustainable Yield (MSY) and optimum fishing effort of Male Mackerel landed at Batulicin Fishing Port; and 3) Analyzing the Utilization Level of Male Mackerel landed at Batulicin Fishing Port. The research was conducted using Purposive Sampling method, observation, questionnaire and interview. Data analysis using the Production Surplus Model method, Catch Per Unit Effort, Maximum Sustainable Yield and Utilization Level. Research results of Male Mackerel landed at Batulicin Fishing Port for 10 years (2014–2023) with the highest Catch Per Unit Effort (CPUE) value in 2018 at 1.9171 tons/trip and the lowest in 2022 at 0.3954 tons/trip. The Maximum Sustainable Yield (MSY) value is 691.66496 tons/year, and the optimal fishing effort value in 10 years is 665 trips/year. The value of the Utilization Level fluctuates, in 2023 it is 38.464% which is classified as a medium level utilization criterion.

Projected impacts of climate change on the spatial distribution and habitat preference of tropical tuna in the Pacific Ocean.

Infectious marine diseases are often highly sensitive to shifting environmental conditions. Data limitations in difficult to access species often impede marine disease investigation. However, fishery-dependent data can allow for expanded coverage in some systems. The emergence of black eye syndrome (BES) of Bering Sea snow crab (Chionoecetes opilio) coincided with massive environmental and ecological shifts in the sea, necessitating improved disease monitoring towards better understanding stock health. Here, we combine fishery-dependent data from the Alaska Department of Fish and Game Bering Sea crab observers programme and hindcasted bottom water conditions from a regional ocean model to explore potential drivers of BES in Bering Sea snow crab using spatially explicit generalized linear mixed models (N = 719 048 crab). BES was positively associated with temperature, low pH, crab size, shell condition and local snow crab density (as catch-per-unit-effort (CPUE)). The associations of temperature and localized CPUE with BES are consistent with leading hypotheses explaining the recent snow crab population collapse, suggesting similar drivers, but their mechanisms influencing BES remain unclear. Fishery-dependent data collection remains an integral part of management, providing opportunities for expanded disease monitoring efforts. This article is part of the theme issue 'Managing infectious marine diseases in wild populations'.

India is a major player in global fisheries, with Coilia dussumieri being a significant species. This study investigates the spatiotemporal distribution of C. dussumieri along the Mumbai coast, focusing on the influence of environmental factors. Data on fish catch and environmental variables (Sea surface temperature (SST), salinity, pH, Sea surface height (SSH), current speed (CS), and chlorophyll-a were collected during fortnightly surveys. The association between these factors and Catch Per Unit Effort (CPUE) was modelled using Boosted Regression Trees (BRT). Results revealed that salinity, chlorophyll-a, and SST were the most influential factors, with optimal ranges observed for each. The model demonstrated a non-linear and interactive effect of salinity and chlorophyll-a on CPUE. A greater percentage of juveniles were found in the catch, according to an analysis of length-frequency data, underscoring the need of taking juvenile populations into account when developing management plans. This work provides significant insight on the ecological needs of C. dussumieri and highlights the necessity of managing fisheries using an ecosystem-based strategy that takes environmental factors and juvenile population dynamics into account.

This research aimed to analyze the catch composition, CPUE (Catch per unit effort), and productivity between two bait types (small crabs and trash fish) associated with rakkang traps in Bawah Layung Village, Tanah Laut Regency, Indonesia. The method used was a field experiment with a randomized block design, and the data were analyzed using analysis of variance (ANOVA). Research activities were conducted between June and September 2025, where a total of 620 rakkang units were deployed around mangrove areas. The results showed that the rakkang captured Scylla paramamosain (77.74%) was 3.5 times higher than S. tranquebarica (22.26%), with species-specific preferences. S. paramamosain outnumbered S. tranquebarica in terms of CPUE and productivity rates (p < 0.05). The CPUE for rakkang traps baited with small crabs (0.53 ind./trap) was considerably higher than using trash fish (0.14 ind./trap). Similarly, the productivity rate was much higher with small crabs (1.71 ind./h) compared to trash fish (1.05 ind./h). Small crab bait proved significantly more effective than trash fish (p < 0.05). These findings suggest that optimizing bait choice, specifically using small crabs, can contribute to more efficient and sustainable mud crab fisheries, potentially reducing bycatch and supporting conservation efforts. The capture of both legal-sized and undersized crabs emphasizes the need for species-specific management to balance market demand with sustainable fisheries.

ABSTRACT The white-clawed crayfish Austropotamobius pallipes complex populations are declining in Italy, mainly due to habitat alteration, invasive alien species and pollution. This study assessed the conservation status and updated the distribution of A. pallipes complex in Foreste Casentinesi National Park (FCNP) (Tuscany and Emilia-Romagna, Central Italy) during three years of sampling (2021–2023). The abundance index Catch Per Unit Effort (CPUE) was used for comparing data among different sites and between the current and a previous sampling period (2012–2016). Overall, in the FCNP, the species experienced a decline in its populations over time, particularly severe in the Tuscan side while in the Emilia-Romagna sites a more stable situation was found. The main causes of this decline could be attributed to the invasive North American raccoon (Procyon lotor), whose distribution mainly overlaps with Tuscan crayfish populations, but also poaching episodes and the alteration of rainfall regime. Moreover, the presence of microsporidiosis and of individuals with blue colouration was reported. These findings emphasize the urgent need of coordinated actions for the conservations of A. pallipes complex including alien species management, habitat protection and long-term monitoring.

ABSTRACT Objective Red Snapper Lutjanus campechanus is an economically and ecologically important fish for the Mississippi coast. Sustainability concerns are of importance to both stakeholders and managers. The objective of this work is to understand the environmental, habitat, and fishery characteristics that influence catch per unit effort of sublegal- and legal-sized Red Snapper in the northern Gulf of America (also known as the Gulf of Mexico). Methods We used descriptive statistics to understand patterns of habitat- and depth-specific catch per unit effort (CPUE). To explore the factors that determine catch, we employed a gradient-boosting ensemble machine learning technique on CPUE. Continuous CPUE data were modeled by converting them to a binary variable, above and below mean ln(CPUE + 1). We used data from a scientific survey of sublegal- and legal-sized Red Snapper (>406.5 mm TL) in the region collected using vertical longline from 2016 to 2019. A suite of predictors (termed “features”) reflecting fishing season, habitat, and environmental characteristics was used in machine learning models. Results In the descriptive analysis of CPUE, we found that positive CPUE for both sublegal- and legal-sized fish was observed at artificial reef and oil and gas platforms in both the mid and deep strata. Conversely, CPUE in undifferentiated bottom habitat was low for all depth strata, with only a single, sublegal fish recorded in the deep depth stratum. Catch-per-unit-effort ln(CPUE + 1) was evaluated, and model output was assessed using variable importance metrics and Shapley additive explanation values for visualization and to determine the direction and magnitude of feature influence. Models were created for both sublegal- and legal-sized Red Snapper. Both models achieved accuracies above 0.90. For sublegal Red Snapper, greater-than-mean ln(CPUE + 1) was associated with high surface salinity and small hook size. For legal-sized Red Snapper, below-mean ln(CPUE + 1) was associated with small hook size. Conclusions Our descriptive analysis indicated that CPUE was greatest in structured habitats. The machine learning model indicated that the variables that predicted binary CPUE for the sublegal- and legal-sized fish were different. For both size-classes examined, our findings that hook size was an important predictor of the binary natural-log-transformed CPUE variable has implications to selectivity and perhaps gear restrictions in the fishery. These analyses can inform fisheries managers of the factors that are most influential in the catch of sublegal- and legal-sized Red Snapper in the study region.

Artisanal fisheries operating within protected coastal systems play a critical role in sustaining local livelihoods while interacting closely with ecologically sensitive environments. This study provides an integrated assessment of a multigear artisanal fishery operated by a cooperative society in Barra Zacapulco, located within the core zone of La Encrucijada Biosphere Reserve on the southern Pacific coast of Mexico. Catch data derived from cooperative landing records and monitored fishing trips were used to analyze catch composition, catch per unit effort (CPUE), relative biomass, by-catch, and seasonal patterns across different fishing gears. In addition, socio-economic surveys were conducted to characterize fishers’ profiles and perceptions of fishery trends and environmental change. Results revealed a multispecific fishery strongly structured by fishing gear and hydrological seasonality. Finfish catches were concentrated during the dry season, whereas shrimp exploitation was closely linked to the rainy season, when increased freshwater discharge enhances lagoon productivity and connectivity. Cast nets emerged as the most widely used and comparatively balanced gear, while stow nets exhibited higher shrimp efficiency but generated substantially greater by-catch, including species of conservation concern. Socio-economic findings highlighted a locally rooted and experienced fishing community, but also pointed to challenges related to aging fishers, limited formal education, and the underrepresentation of women in capture activities. Fishers’ perceptions of declining catches and environmental degradation—particularly mangrove loss, sedimentation, pollution, and reduced fishing areas—were consistent with empirical and historical evidence. These findings underscore the need for integrated and participatory management strategies that incorporate seasonal dynamics, promote selective fishing practices, mitigate by-catch, and strengthen local capacities to ensure the sustainability of artisanal fisheries within protected areas.

The biodiversity crisis in freshwater habitats is intensifying due to human-induced changes, leading to significant biodiversity loss. Freshwater fish, in particular, are experiencing alarming population declines. Effective monitoring by direct capture is critical to track and mitigate these losses, but small water bodies often present challenges for active monitoring methods. In such cases, passive sampling techniques, like traps, offer a practical alternative for conservation agencies, though their effectiveness in monitoring fish biodiversity for conservation purposes is not yet fully understood. This study evaluates the effectiveness of two passive sampling techniques fyke nets and umbrella-shaped traps (umbrella traps) for capturing fish diversity in small freshwater habitats. Sampling was conducted overnight in 39 water bodies, and fish density was quantified using catch per unit effort (CPUE). A beta regression model was applied to analyze species capture rate and the influence of habitat parameters on catch success. The CPUE revealed a 6.82-fold higher mean individual capture rate and a 2.05-fold higher species richness per deployment for umbrella traps compared to fyke nets indicating significantly higher sampling efficiency under comparable conditions. Rarefaction curves and non-metric multidimensional scaling analyses demonstrated that umbrella traps more effectively characterized littoral fish diversity and captured higher species richness than fyke nets in small freshwater bodies. The study underscores the utility of umbrella traps as a reliable tool for assessing fish diversity through direct capture, particularly for monitoring elusive or invasive non-native species. These findings aim to enhance conservation oriented species capture and inform conservation planning in often-overlooked small freshwater ecosystems, which play a crucial role in the long-term conservation of fish species.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10661-026-15133-3.

Scad fish ( Decapterus ruselli ) is an important pelagic fishery commodity in the Kendari Waters, but fluctuations in catch are often influenced by oceanographic dynamics. This study analyzed the relationship between oceanographic conditions and the abundance of scad fish based on fishermen's catch per unit effort (CPUE) data from 2022 and satellite- derived parameters, including sea surface temperature (SST), salinity (SSS), chlorophyll-a (CHL-a), and sea surface height (SSH). Spatial-temporal analyses were performed using Pearson correlation. Results revealed distinct seasonal variations with the highest CPUE observed in September (~665 kg trip-1). Significant negative correlations were found between SST (r=-0.36; p=0.041) and SSH (r=-0.30; p=0.048), indicating that lower temperatures and sea surface heights correspond to higher fish abundance reflecting the influence of upwelling processes that enhance nutrient availability and productivity. These findings confirm that physical oceanographic factors are more dominant than chemistry or biology in determining the availability of scad fish. The eastern period (August–October) was identified as the most productive and potential phase for fishing activities. This research provides a scientific basis for season-based fisheries management and oceanographic dynamics, while encouraging the sustainable use of fish resources.

The Red Sea and the Arabian Gulf are ecologically distinct yet socio-economically vital marine systems, where fisheries underpin food security, livelihoods, and coastal economies in the Middle East. This review presents a comparative assessment of fisheries status, exploitation patterns, drivers of illegal, unreported, and unregulated (IUU) fishing, and governance capacity in both regions, synthesizing peer-reviewed studies, regional assessments, and institutional data. Results indicate that 60% - 75% of stocks in the Red Sea and 70% - 85% in the Arabian Gulf are fully exploited or overexploited, with declining catch-per-unit-effort (CPUE) and reduced mean trophic levels, reflecting “fishing down the food web”. Despite shared pressures, the regions differ markedly in ecological and institutional context. The Red Sea’s high biodiversity and complex reef habitats support predominantly artisanal, multi-species fisheries, offering some ecological resilience but leaving high-value demersal species vulnerable to targeted exploitation. In contrast, the Arabian Gulf’s lower biodiversity, extreme environmental conditions, and mechanized, species-focused fisheries heighten susceptibility to overfishing. IUU fishing is a significant driver of unsustainable exploitation in both regions, influenced primarily by socio-economic pressures (35% - 40%), governance gaps (25% - 30%), environmental stressors (15% - 20%), and technological or market incentives (15% - 20%). Regional differences, such as weak monitoring and limited compliance in the Red Sea versus fleet overcapacity in the Arabian Gulf, create reinforcing feedback loops of declining biomass, reduced CPUE, and escalating fishing pressure. The study highlights the urgent need for ecosystem-based, region-specific fisheries management that integrates ecological complexity, socio-economic dependence, and governance capacity. Strengthening monitoring, surveillance, fleet regulation, data integration, and regional cooperation is essential to break the overfishing-IUU cycle and ensure long-term sustainability and resilience of these marine ecosystems.

Bigeye tuna (Thunnus obesus) is an economically important commodity landed at Benoa Port, yet it currently faces challenges regarding declining catch efficiency and economic value. This study aims to analyze Catch per Unit Effort (CPUE) trends, estimate Maximum Sustainable Yield (MSY), and examine the dynamics of economic production value to determine appropriate management strategies. The research employed a survey method utilizing operational landing time-series data from 2020 to 2024. Data were analyzed using the Gordon-Schaefer model. The results indicated that a surge in fishing effort in 2024, reaching 456 trips, was not commensurate with the catch, causing the CPUE to drop significantly to its lowest value of 2.16 tons/trip. The MSY was estimated at 1,272.12 tons/year with an optimum fishing effort of 489.41 trips/year. Although the resource utilization rate remains in the Moderate Exploited category (77.3%), the fishing effort level has approached a critical point, reaching 93.2% of the optimum limit. Economically, there was a significant decline in production value from IDR 58.1 billion in 2020 to IDR 19.6 billion in 2024, attributed to falling prices and smaller fish sizes. It is concluded that tuna fisheries management in Benoa requires the immediate implementation of fishing effort restrictions and an orientation towards improving catch quality to prevent overfishing and restore economic profitability.

Marine Fishery Advisories (MFAs) in the form of Potential Fishing Zone (PFZ) advisories, developed and disseminated by the Earth System Science Organization—Indian National Centre for Ocean Information Services (ESSO-INCOIS), predict short-term fish aggregation zones in the open sea for the fishing community except during fishing ban periods in India. Hence, MFAs have the potential to enhance the economic benefits for marine fishers due to the reduction in the search time during fishing, which ultimately decreases fuel (e.g., diesel) consumption. Considering these potential advantages, the present study is designed to investigate the economic benefits in terms of reductions in the diesel consumption for the mechanized (MC) fishing sector in selected Fish Landing Centers (FLCs) and Fishing Harbors (FHs) across the coastal districts of Odisha based on stratified sampling. A comparative analysis was carried out on fishing expeditions in the PFZ Notified Area (PNA) and Non-Notified Area (NNA) based on a field survey conducted among marine fishers across these FLCs/FHs operated by MC fishing craft during 2020–21. It was found from the present investigation that the average daily fishing expenditure can be reduced from INR 36,000 to INR 19,000 due to the usage of MFAs, which implies an approximate 45% reduction in daily spending on fishing expeditions. Moreover, the catch per unit effort (CPUE) and net profits of the fishers according to the present analysis provide an overall picture of the MFA usage and economic benefits. The reduction in the fishing expenditure owing to the lower fuel consumption using MFAs are directly associated with sustainable fishing practices, which are also connected with co-targets such as fish stock preservation and maintaining an acceptable ecosystem health under Sustainable Development Goal (SDG) 14. Furthermore, the societal impacts due to the use of MFAs on the fishing community were also studied through a lifecycle assessment. The present investigation illustrated the multiple ecosystem and human co-benefits associated with the reduction in search time through the utilization of MFAs, which can be invested into making fishery operations sustainable for all stakeholders.

A machine learning-based policy–utility framework was developed to assess trap mesh sizes (35–80 mm) in the Marbled Flounder fishery and reframe traditional selectivity analysis into a policy-oriented decision context. A utility function integrating catch per unit effort (CPUE), the immature proportion, and the bycatch ratio was constructed from experimental data collected in 2015–2016 and assessed under multiple policy weighting scenarios. Gradient boosting models trained on the 2016 data and validated with the 2015 data demonstrated strong predictive accuracy. The empirically optimized weighting set (α* = 0.79, β* = 2.36, and γ* = 0.79) produced high agreement between predicted and observed utilities (root mean square error ≈ 0.22; r = 0.901). Variable importance analysis identified the immature proportion as the main driver of utility variation; bycatch ratio and CPUE made smaller contributions. Scenario-based simulations showed a shift in the optimal mesh size, from 65 mm in 2015 to 80 mm in 2016, that reflects interannual changes to population size structure and bycatch composition. Policy regret analysis (comparing 65 mm to 80 mm) indicated consistently low regret (ΔU ≈ 0.12–0.15) and relative regret (<80%) values. This integrated utility–regret framework provides a dynamic, policy-relevant tool for linking trap selectivity information to management objectives.

ABSTRACT The Northeast Atlantic is one of the most crucial foraging grounds for juvenile loggerhead ( Caretta caretta ) and leatherback turtles ( Dermochelys coriacea ), while also serving as an important fishing area for the Andalusia surface longline fishery. The main aim of present study is to assess the sea turtle interaction with the Andalusia pelagic longline fleet operating in the Northeast Atlantic. Between 2004 and 2023, a total of 235 sea turtles were observed incidentally caught during longline fishing operations in 975,379 hooks. These records correspond to data collected by the onboard observer program of the Spanish Institute of Oceanography (IEO), which covered 4.82% of total fishing activity in the area. Loggerhead turtles ( n = 218) and leatherbacks ( n = 17) were the only turtle species caught, with catch rates of 0.251 and 0.017 turtles per 1000 hooks, respectively. A generalized linear mixed model (GLMM) with negative binomial distribution revealed that season and moon phase significantly influenced catch per unit effort (CPUE), with spring ( p = 0.024) being associated with fewer incidental captures and new moon ( p = 0.035) with higher captures. Additionally, increased distance from the coast was positively correlated with higher CPUE ( p = 0.006), while latitude exhibited a negative relationship with CPUE ( p = 0.020). These findings contribute to our understanding of the variables involved in the incidental capture of sea turtles in surface longline fisheries targeting swordfish around the Canary Islands and may support the development of improved management strategies for their conservation.

Abstract Understanding the distribution and intensity of fishing activity is fundamental to assessing anthropogenic impacts on target species and surrounding ecosystems. Here, we present a method to integrate digital vessel tracking data from automatic identification system and vessel monitoring system with sales slips to map inter-annual fishing pressure in a small-scale fishery (SSF; vessels <12 m) across multiple spatial resolutions. We found that the Norwegian wrasse fishery (a passive gear fishery) experienced proportional declines in both fished area and reported catch (22% each between 2021 and 2023) over the study period, and that spatial restrictions on fishing activity reduced the regional catch. Fishing activity was highest between Bergen and Stavanger, and focused mainly within coastal archipelagos, rather than fjord regions. We grouped fishing pressure at three spatial scales (regional, 5 and 1 km2) and calculated annual catch per unit effort (CPUE) per polygon, then analysed the relationships between CPUE between consecutive years for each species. This revealed a quadratic relationship for the three main target species, corkwing (Symphodus melops), goldsinny (Ctenolabrus rupestris), and ballan wrasse (Labrus bergylta), where CPUE was lower than expected in polygons which had experienced high CPUE in the preceding year. The reduction in CPUE indicated that intensive wrasse fishing reduces densities of target species, and the mapping method presented in this study can facilitate for improved targeted studies of fishing impacts on these ecologically important species. We discuss the limitations of integrating multi-source spatial datasets in SSF monitoring and offer recommendations for future spatially explicit models of fishing pressure.