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Marine heatwaves (MHWs) have measurable impacts on marine ecosystems and reliant fisheries and associated communities. However, how MHWs translate to changes in fishing opportunities and the displacement of fishing fleets remains poorly understood. Using fishing vessel tracking data from the automatic identification system (AIS), we developed vessel distribution models for two pelagic fisheries targeting highly migratory species, the U.S. Atlantic longline and Pacific troll fleets, to understand how MHW properties (intensity, size, and duration) influence core fishing grounds and fleet displacement. For both fleets, MHW size had the largest influence on fishing ground area with northern fishing grounds gaining and southern fishing grounds decreasing in area. However, fleet displacement in response to MHWs varied between coasts, as the Atlantic longline fleet displaced farther in southern regions whereas the most northern and southern regions of the Pacific troll fleet shifted farther. Characterizing fishing fleet responses to these anomalous conditions can help identify regional vulnerabilities under future extreme events and aid in supporting climate-readiness and resilience in pelagic fisheries.

Twelve commercial species exploited in the eastern Guangdong and southern Fujian waters were assessed using the Catch-Maximum Sustainable Yield (CMSY) and Bayesian Schaefer Model (BSM) methods. The carrying capacity (k), intrinsic rate of population growth (r), maximum sustainable yield (MSY), and relative biomass (Bend/k and B/BMSY) were estimated. The current stock status was defined by B/BMSY and fishing mortality (F/FMSY). The results indicate that seven stocks were overfished or below safe biological limits (B/BMSY < 0.5 or F/FMSY > 1), two stocks were in a recovery phase (0.5 < B/BMSY < 1, F/FMSY < 1), and three stocks were under sustainable fishing pressure with healthy biomass, capable of producing yields close to the MSY (B/BMSY > 1, F/FMSY < 1). The stock statuses are consistent with previous studies on the utilization of pelagic fisheries in the eastern Guangdong and southern Fujian waters and with those assessments in other waters. The results of the assessments suggest that these stocks could be expected to produce higher sustainable catches if permitted to rebuild; thus, more effective and proactive management is needed in this upwelling fishing ground. [ABSTRACT FROM AUTHOR]

Abstract The effects of pelagic trawling on the health and welfare of Atlantic herring (Clupea harengus L.) were investigated on a refrigerated seawater vessel operating in the North Sea. A total of 495 Atlantic herring (Clupea harengus L.) were sampled during five hauls from two fishing trips in September 2021 and 2022. For assessments of consciousness and mortality, a Reflex Action Mortality Predictor test (i.e. RAMP-test) was used on herring collected following trawling and pumping. Inspections for external and internal damage or wounds were performed via morphological welfare indicators and analyses of photos and radiographs. In addition, blood samples were taken and analysed for haematological indicators of stress. Following trawling and pumping, only 5% of the investigated herring showed signs of external wounds associated with the morphological indicators of welfare, and no internal damage was observed in the radiographic inspections. However, 96% of the assessed herring scored 0 on all three reflexes included in the RAMP-test and were therefore judged dead. On average, herring lost 95% of their scales, while 95% of herring had a very high degree of ruptured red blood cells (i.e. haemolysis). Extensive scale loss results in a deterioration of the skin's protective barrier function, which in turn impairs the osmoregulatory capacity of the herring. This was evident by elevated levels of plasma osmolality and circulating chloride concentrations, which could also likely explain the high occurrence of haemolysis in captured herring. Extended trawling time and larger catch size proved to be two important factors to consider, as the former led to increased plasma levels of osmolality, whereas the latter was associated with elevated plasma levels of lactate and cortisol. In conclusion, the high mortality appears to be influenced by a combination of factors such as severe stress, loss of osmoregulatory ability, crowding density within the trawl, and extended trawling times. This study provides important information on the welfare of wild Atlantic herring caught using pelagic trawls and highlights areas where improvements can be made to safeguard the welfare of fish captured in pelagic fisheries in the future.

Aiming at the information asymmetry problem in the supply chain of pelagic fishery aquatic products, this paper constructs a traceability system for pelagic fishery aquatic products with the help of blockchain and fishery networking technologies. At each level, the traceability analysis is conducted using distinct technical methods and evaluation criteria. The system is designed and operated systematically by integrating pelagic fishery fishing enterprises, transportation enterprises, processing enterprises, sales enterprises, consumers and regulatory departments. By relying on the technical platform of fishery networking, the functions of the traceability system of marine fishery products are also strengthened. The corresponding traceability system is constructed by taking tuna as an example, with a view to improving the credibility and safety of information traceability of China′s pelagic fishery aquatic products industry chain, reducing the information asymmetry of various subjects of pelagic fishery, and providing a better solution to achieve the purpose, which is to strengthen the credibility and security of information traceability of China′s pelagic fisheries industry chain, reduce the information asymmetry of pelagic fisheries, and provide references and lessons for the high-quality, sustainable development of pelagic fisheries industry.

Fish object detection and counting in pelagic fisheries face many challenges in complex environments. Sonar imaging technology offers a solution because it generates high-resolution images underwater. In this paper, we propose a sonar-based fish object detection and counting method using an improved YOLOv8 combined with BoT-SORT to address issues such as missed detection, false detection, and low accuracy caused by complex factors such as equipment motion, light changes, and background noise in pelagic environments. The algorithm utilizes the techniques of lightweight upsampling operator CARAFE, generalized feature pyramid network GFPN, and partial convolution. It integrates with the BoT-SORT tracking algorithm to propose a new region detection method that detects and tracks the schools of fish, providing stable real-time fish counts in the designated area. The experimental results indicate that while focusing on maintaining a lightweight design, the improved algorithm achieved a 3.8% increase in recall and a 2.4% increase in mAP0.5 compared to the original algorithm. This significantly impacts scientific and rational fishery planning, marine resource protection, and improved productivity. At the same time, it provides important data support for marine ecological monitoring, environmental protection, and fishery management, contributing to sustainable fishery development and marine ecology preservation. [ABSTRACT FROM AUTHOR]

This study delves into the foraging ecology of the cookiecutter shark (Isistius brasiliensis) in the Saint Peter and Saint Paul Archipelago (SPSPA), assessing bite marks on pelagic fishes collected between March and September 2018. Examination of 200 individuals from five species revealed the shark's predilection for targeting adult fish, ensuring efficient removal of energy‐rich tissue layers. However, a notable exception is Thunnus albacares, preyed on predominantly during its juvenile stage, possibly due to vertical spatial segregation. Recent bites were pervasive across species, with wahoo displaying a distinctive pattern. Cookiecutter shark bites predominantly targeted the lateral body portion (>55%) except for yellowfin tuna, which exhibited a preference for the ventral region (95%). The estimated length distribution suggests the SPSPA as a potential nursery area for cookiecutter sharks. Bite mark positions and frequencies may be linked to fish behavior, swimming velocity, and fishing gear strategy, highlighting the complex interplay in pelagic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Yellowfin tuna, Thunnus albacares, represents an important component of commercial and recreational fisheries in the Gulf of Mexico (GoM). We investigated the influence of environmental conditions on the spatiotemporal distribution of yellowfin tuna using fisheries’ catch data spanning 2012–2019 within Mexican waters. We implemented hierarchical Bayesian regression models with spatial and temporal random effects and fixed effects of several environmental covariates to predict habitat suitability (HS) for the species. The best model included spatial and interannual anomalies of the absolute dynamic topography of the ocean surface (ADTSA and ADTIA, respectively), bottom depth, and a seasonal cyclical random effect. High catches occurred mainly towards anticyclonic features at bottom depths > 1000 m. The spatial extent of HS was higher in years with positive ADTIA, which implies more anticyclonic activity. The highest values of HS (> 0.7) generally occurred at positive ADTSA in oceanic waters of the central and northern GoM. However, high HS values (> 0.6) were observed in the southern GoM, in waters with cyclonic activity during summer. Our results highlight the importance of mesoscale features for the spatiotemporal distribution of yellowfin tunas and could help to develop dynamic fisheries management strategies in Mexico and the U.S. for this valuable resource.

Fish object detection and counting in pelagic fisheries face many challenges in complex environments. Sonar imaging technology offers a solution because it generates high-resolution images underwater. In this paper, we propose a sonar-based fish object detection and counting method using an improved YOLOv8 combined with BoT-SORT to address issues such as missed detection, false detection, and low accuracy caused by complex factors such as equipment motion, light changes, and background noise in pelagic environments. The algorithm utilizes the techniques of lightweight upsampling operator CARAFE, generalized feature pyramid network GFPN, and partial convolution. It integrates with the BoT-SORT tracking algorithm to propose a new region detection method that detects and tracks the schools of fish, providing stable real-time fish counts in the designated area. The experimental results indicate that while focusing on maintaining a lightweight design, the improved algorithm achieved a 3.8% increase in recall and a 2.4% increase in mAP0.5 compared to the original algorithm. This significantly impacts scientific and rational fishery planning, marine resource protection, and improved productivity. At the same time, it provides important data support for marine ecological monitoring, environmental protection, and fishery management, contributing to sustainable fishery development and marine ecology preservation.

To explore the current risk status of China's pelagic fishery industry in the context of current global climate change and assess the risk level of the industry, the data related to China's pelagic fishery industry and ocean climate change data from 2009 to 2021 were analyzed. The risk assessment index system was constructed based on the pressure-state-response(PSR) model framework, and the risk index model was applied to determine the level of pressure, state and response risk of China's pelagic fisheries. The risk assessment results showed that the total risk index of the pelagic fishery from 2009 to 2021 showed a fluctuating upward trend due to the influence of ocean climate changes and ocean extreme disasters. The changing trend of the pressure risk index was generally similar to the change of the total risk index, indicating that climate change factors occupied a great proportion in affecting the risk of the pelagic fishery industry. The overall increasing trend of the state risk index indicated that the sensitivity of China's pelagic fisheries to cope with climate change pressure had become greater. The overall trend of fluctuating increase in the response risk index indicated that the adaptive capacity and recovery ability of China's pelagic fisheries themselves were gradually strengthening. Based on this, countermeasures were proposed from both external climatic factors and internal socio-economic factors, which could help enhance the risk prevention capability of China's pelagic fisheries and provide a reference for achieving high-quality development of China's pelagic fisheries. [ABSTRACT FROM AUTHOR]

Simple Summary: Blue shark populations are currently declining, caused mainly by the impact of overfishing from industrial fishing vessels in the open oceans. However, there is a paucity of comprehensive biological and habitat data concerning the reproductive characteristics of blue shark species in the Indian Ocean. In response to the call made by the Indian Ocean Tuna Commission (IOTC) to provide valuable parameters for the conservation of blue shark resources, this study collected observer data from the Indian Ocean longline fishery targeting tuna between 2010 and 2020. Through rigorous statistical analysis, it was determined that the estimated length at sexual maturity for male blue sharks is 161.4 cm and 179.3 cm for females. Moreover, the average litter size was found to be 33.7 pups. The study suggests the existence of a possible seasonal migratory pattern for pregnant blue sharks, with the first and fourth quarters of the year being potential mating grounds in proximity to the equatorial region of the Indian Ocean. Additionally, the temperate marine areas of the Indian Ocean were identified as crucial habitats for parturition and juvenile development of blue shark species. Consequently, it is strongly recommended to implement more scientifically informed and ecologically sustainable operational strategies in these designated areas. Due to the limited biological research on the blue shark in the Indian Ocean, such as the lack of a clear understanding of its reproductive biology and distribution, our study analyzed and evaluated the fork length distribution, sexual maturity length, reproductive capacity, and spatiotemporal distribution of blue sharks based on biological data and capture location information collected in the western Indian Ocean from 2010 to 2020. The objective of this study is to provide reliable biological information important in performing future stock assessments vital for species conservation in this region. A total of 791 male (33–249.5 cm FL) and 803 female (12–349.6 cm FL) blue sharks were collected in the West Indian Ocean. We used the morphology of the sexual organs to ascertain their sexual maturity. Results show that the observed size at 50% sexual maturity of male blue sharks in the West Indian Ocean was 161.4cm FL (192.4 cm TL) for males and 179.3 cm FL (213.9 cm TL) for females based on logistic curve analysis. The average litter size of pregnant blue sharks was 33.7 pups. There were significant differences in the distribution of blue shark individuals with different sexual maturity levels in different quarters (p < 0.05). This study suggests that the area near the equator in the Indian Ocean from October to March of the following year may be the mating ground for blue sharks, while the temperate waters in the Indian Ocean are the nursery ground and parturition ground for pregnant and juvenile throughout the whole year. Therefore, it is recommended to adopt a more scientific and reasonable operational method in these areas. [ABSTRACT FROM AUTHOR]

Studies relating the populational structure of target species to operational and environmental variables contribute directly to the management of the fisheries in these resources. Therefore, this study aimed to provide data on fishing and ecology of the swordfish (Xiphias gladius) caught by the Brazilian longline fleet operating in the western Atlantic between 2010 and 2016. Generalized additive mixed models were used to evaluate the relationship between explanatory variables and responses based on Catch Per Unit of Effort (CPUE) data. Results show that the Brazilian longline fleet catches the swordfish mostly between latitudes of 5°N to 30°S and longitudes of 20° to 50°W and that the swordfish prefers temperatures under 25°C at depths below 60 meters. The species showed a tendency toward intermediate light intensity, predominating in the crescent moon phase, and a preference for areas with low chlorophyll concentrations. Our findings on operational and environmental interactions with swordfish CPUE suggest areas and times that can be used by fishing fleets and government institutions as a starting point for swordfish management strategies. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is among the most vulnerable semi-enclosed seas to climate change. Multiple oceanic changes occur besides warming that can generate numerous ecological, social, and economic risks, challenging fisheries management at various spatial scales—from local to international. In this study, we applied a semi-quantitative climate risk assessment (CRA) to the Mediterranean small pelagic and demersal fisheries in relation to a diversity of climate-related drivers and impacts. We assessed the risks of climate change effects on demersal and small pelagic fisheries resources, fishing operations, livelihoods, and wider social and economic implications in seven sub-regions of the Mediterranean Sea. Ocean warming, an increase in extreme weather events, and changes in vertical stratification resulted in the most important climate drivers. Overall, climate drivers present higher risks to fishing resources and livelihoods than to fishing operations and wider social and economic impacts. The study puts into evidence geographic differences in terms of the drivers and impacts, with the south-eastern Mediterranean being the sub-region with higher risk levels for both fisheries, while the north-central Mediterranean also showed important risk levels for the demersal fisheries. The study furthermore discusses the most plausible adaptive measures in management, policy, research, and livelihoods to be potentially applied to address high priority risks, as well as various implementation concerns and technical effectiveness issues. Enhancing adaptive fisheries management needs to be the primary strategy for this region to reverse the high number of overfished stocks and build resilience to climate change. [ABSTRACT FROM AUTHOR]

Inshore waters are crucial for fisheries since such areas show a wide range of variations in ecology, mostly considered to shape biotic ecosystems. Despite major fishing activities off Bintulu coast located along the South China Sea operating in the inshore areas and significantly contributing to local fisheries’ economy by Pukat Tarik (dragnet), temporal exchange of fisheries composition in terms of ecological parameters has been little studied. Therefore, temporal changes in pull net fisheries composition and assemblages in relation to the ecological parameters in the inshore waters of Bintulu coast, Sarawak, were observed from May 2016 to April 2017. A total of 63 species belonging to 15 orders of 40 families were recorded, and 11 species found ubiquitous. Species diversity (H´) was recorded higher (2.61) in northeast monsoon, and lower (0.51) in inter-monsoon season, yet the species richness and diversity did not show temporal differences (p>0.05). Among the species Kurtus indicus was recorded the most abundant (58% of the total catch) followed by Photopectoralis bindus (15%) and Opisthopterus tardoore (7%); and the species abundance showed significant temporal differences (p

Marine microplastics are emerging pollutants that impact across levels of marine food chain at a global scale. Its presence was determined on Sardinella lemuru, a commercial pelagic fish that are harvested generally in the Northern Mindanao, consumed locally, and exported worldwide as bottled or canned sardine products. The stomach contents of 600 sardines were examined visually under a microscope, stained with Rose Bengal, and tested with hot needle technique to identify ingested microplastics. These anthropogenic particles were measured and physically classified into fibers, fragments, and films. Results of this study showed that 85% of S. lemuru were already contaminated with 3.74 ± 3.92 # of microplastics even before being processed into various sardine products. These microplastics ranged from 0.12 to 21.30 mm and 80 % were mostly < 2.5 mm size classes. The dominant microplastics were 97.94 % in the form of fibers while 1.52 % and 0.54 % were respectively classified into fragments and films. Method validation by isolating microplastics from spiked samples (n = 30) with three retrieval attempts showed 100% recovery efficiency. While results from Canonical Correspondence Analysis of ingested microplastic data had no relationship with the standard lengths of the sardine and the masses of ingested food materials at varying size classes, the total number of ingested microplastics from 2014 to 2016 were directly correlated (r2=0.91, p=0.003) with the human population at the landing sites along the coastline of northern Mindanao.

With the increased uncertainty introduced through climate change and fishing pressure, having accurate estimates of fish biomass is essential for global ecosystem and economic health. Acoustic surveys are an efficient way to determine population size for pelagic species in the Northeast Atlantic (NEA), but acoustic population estimates still contain uncertainty and are difficult for some species. For example, Atlantic mackerel (Scomber scombrus) is one of the most valuable fisheries in the NEA and is not monitored acoustically, as mackerel lack the swim bladder that provides the strongest acoustic echo (target strength) at common assessment frequencies. For all pelagic species, and especially for mackerel, behavior is a source of variation in acoustic measurements and therefore in population estimates. Behavior is mediated by both extrinsic and intrinsic factors, such as the environment and the life history of the fish. In turn, behavior affects the density of the shoal and the tilt angle of the fish relative to the survey vessel, affecting their target strength, which affects the biomass estimate. Some fish may also undergo an anti-predator response to survey vessels, changing their behavior in response to the survey. Understanding these behaviors and incorporating them into acoustic stock assessment methods can improve the accuracy of population estimates. Individual-based models (IBM) of fish shoals provide a pathway for incorporating behavior into acoustic methods. IBMs have been used extensively to build theoretical models of fish shoals, but few have been successfully tested in lab or field conditions. As computational power and monitoring technology improve, modeling the collective behavior of pelagic fishes will be possible. Novel, interdisciplinary approaches to data collection and analysis will help translate theoretical IBMs to the fisheries science domain. Beyond acoustic stock assessments, this approach can be used to investigate knowledge gaps in the effects of fisheries-induced evolution and the potential for range shifts under climate change. Further work to synthesize existing models and incorporate field data will help determine how environmental, ecological, physiological, and anthropogenic factors, often affecting both behavior and acoustic surveying, are interconnected. Moving from theoretical models to practical applications will be a valuable tool in tackling the uncertainty that accompanies further fisheries exploitation and warming oceans.

Many global fisheries have transitioned to rights-based management to improve bioeconomic outcomes, but several fishing communities have experienced negative social impacts. Negative social impacts are often attributed to a focus on economic efficiency and resource sustainability, with less focus on the distributional equity among fishery participants. Among rights-based systems, limited entry has been used for over a century to reduce excess fleet capacity. In 1991, a limited entry permit system was initiated in the Hawai‘i longline fleet, following years of rapid growth. The Hawai‘i system did not set an ownership cap, which presented a natural experiment to examine distributional equity in the fleet over time. We examined permit ownership changes in the Hawai‘i longline fishery using 27 years of permit transactions, then linked it to logbook landings and commercial dealer data to examine revenue inequality using the gini coefficient. We also analyzed property rights components to better understand how institutional factors affected ownership changes. We found that three distinct permit ownership groups emerged and permits, landings, and revenue became increasingly consolidated among multiple permit owners. The gini coefficient indicated that how the fishery was analyzed significantly affected measures of revenue inequality. One measure indicated that revenue inequality in the Hawai‘i limited entry system was similar to other U.S. fisheries managed by catch shares. Without an ownership cap, distributional equity in the Hawai‘i longline fleet changed significantly over time. Our findings indicate that distributional equity should be considered prior to initiating rights-based transitions in other global fisheries

Marine microplastics are emerging pollutants that impact across levels of marine food chain at a global scale. Its presence was determined on Sardinella lemuru, a commercial pelagic fish that are harvested generally in the Northern Mindanao, consumed locally, and exported worldwide as bottled or canned sardine products. The stomach contents of 600 sardines were examined visually under a microscope, stained with Rose Bengal, and tested with hot needle technique to identify ingested microplastics. These anthropogenic particles were measured and physically classified into fibers, fragments, and films. Results of this study showed that 85% of S. lemuru were already contaminated with 3.74 ± 3.92# of microplastics even before being processed into various sardine products. These microplastics ranged from 0.12 to 21.30 mm and 80 % were mostly < 2.5 mm size classes. The dominant microplastics were 97.94 % in the form of fibers while 1.52 % and 0.54 % were respectively classified into fragments and films. Method validation by isolating microplastics from spiked samples (n = 30) with three retrieval attempts showed 100% recovery efficiency. While results from Canonical Correspondence Analysis of ingested microplastic data had no relationship with the standard lengths of the sardine and the masses of ingested food materials at varying size classes, the total number of ingested microplastics from 2014 to 2016 were directly correlated (r2=0.91, p=0.003) with the human population at the landing sites along the coastline of northern Mindanao. [ABSTRACT FROM AUTHOR]

Many global fisheries have transitioned to rights-based management to improve bioeconomic outcomes, but several fishing communities have experienced negative social impacts. Negative social impacts are often attributed to a focus on economic efficiency and resource sustainability, with less focus on the distributional equity among fishery participants. Among rights-based systems, limited entry has been used for over a century to reduce excess fleet capacity. In 1991, a limited entry permit system was initiated in the Hawai'i longline fleet, following years of rapid growth. The Hawai'i system did not set an ownership cap, which presented a natural experiment to examine distributional equity in the fleet over time. We examined permit ownership changes in the Hawai'i longline fishery using 27 years of permit transactions, then linked it to logbook landings and commercial dealer data to examine revenue inequality using the gini coefficient. We also analyzed property rights components to better understand how institutional factors affected ownership changes. We found that three distinct permit ownership groups emerged and permits, landings, and revenue became increasingly consolidated among multiple permit owners. The gini coefficient indicated that how the fishery was analyzed significantly affected measures of revenue inequality. One measure indicated that revenue inequality in the Hawai'i limited entry system was similar to other U.S. fisheries managed by catch shares. Without an ownership cap, distributional equity in the Hawai'i longline fleet changed significantly over time. Our findings indicate that distributional equity should be considered prior to initiating rights-based transitions in other global fisheries. [ABSTRACT FROM AUTHOR]

Most selectivity experiments employ either the covered codend or paired gear methods. It is not always possible, however, to use these methods. Owing to operational, biological and/or environmental considerations, there may be no obvious way or it may be inappropriate to pair the test and control data. Hence, it will not be possible to estimate the selectivity of the gear and its uncertainty using standard statistical methods. This study presents a methodology for analysing the selectivity of fishing gears from unpaired test and control data. The uncertainty in the control and test population structures is accounted for by using a double bootstrapping procedure that takes into account both between-haul and within-haul variation. This bootstrapping approach is used to assess the selectivity of two different devices, a 139.5 mm T90 codend and a 135.9 mm codend with 140.9 mm lateral exit windows, in the Barents Sea pelagic cod trawl fishery. The purpose of the experiment was to test and compare the performance of the two devices in pelagic trawl fisheries, where high densities of fish can be encountered. Significant differences were detected between the T90 codend and the codend with the exit windows but only for sizes of cod between 55 and 76 cm.

Abstract Ensuring the sustainable use of the small pelagic fish stocks and the sustainable management of the fisheries exploiting them is a significant challenge faced by countries in Northwest Africa. Small pelagic fish constitute the bulk of the landings in this region, with annual catches of the main species ranging from approximately 1.7 to 2.5 million tonnes over the last few decades. Many of the main pelagic stocks are distributed across the 200 nautical-mile boundaries of the sub-region, and are shared bilaterally or sub-regionally among countries of Western Africa. These resources, which migrate along the Northwest African coast, are exploited by local fleets of both the artisanal and industrial sectors, as well as distant water fishing vessels from Europe, Asia, and Central America. The transboundary nature of these fish stocks calls for joint action with respect to their monitoring and management. In 2001, the Food and Agriculture Organization of the United Nations created a permanent working group on the assessment of small pelagic fish off Northwest Africa, which today reports to the Fishery Committee for the Eastern Central Atlantic. As a result of this Working Group's efforts, more consistent series of catch and effort and annual abundance indices of the main small pelagic fish species are now available, and significant improvements in sampling intensity have been achieved. Furthermore, consolidated annual advice is provided at a regional scale on the state of these resources that complements the national assessment and management advice systems. This paper provides some reflections on the contributions of the Working Group to science-based fisheries management and possible future actions that could further strengthen the collaborative momentum gained through this type of regional collaboration. [ABSTRACT FROM AUTHOR]

Bigeye tuna ( Thunnus obesus, Scombridae) are a globally important commercial fish. About 60% of the world's bigeye is caught in the Pacific Ocean, where stocks have been subject to overfishing and longline fleets are governed by increased conservation measures. One conservation measure entails multilateral bigeye quota reductions. Since 2010, quota reductions have resulted in four extended closures for Hawai`i longliners. Previous research indicated that regulatory closures may result in differential socioeconomic impacts, but little is known about how four extended closures may affect fishers and fishing trips in a diverse longline fleet with 142 active vessels. The purpose of this research is to assess the trip-level impacts of closures on Hawai`i longliners and determine whether impacts could be lessened while sill meeting conservation measures. To do this, economic data and longline logbooks for Hawai`i longliners were analyzed from 2010 to 2015, and 28 longline fishers were interviewed in Fall 2015. Vessels allowed to fish during closures spent nearly two more days at sea not fishing compared to the same month in years without a closure, with no significant difference in trip length. Vessels with special permits are allowed to fish closer to port during closures, while the larger vessels (25% of the fleet) were restricted from retaining bigeye between 32 and 61 days a year, raising equity concerns across the fleet. Our findings also suggest that two levels of collective action may be needed to meet Pacific-wide economic and conservation goals for an economically and ecologically important pelagic common-pool marine resource. [ABSTRACT FROM AUTHOR]

This paper explores the economic and biological effects of exploiter and species interactions in a multiplayer, multispecies fishery. To this end, a partial ecosystem model for three key pelagic species in the Northeast Atlantic (Norwegian spring-spawning herring, mackerel and blue whiting) is developed and coupled with an economic model describing harvesting behavior of three major exploiters. We explore the effects on the fishery under assumptions on plausible interaction parameters between the harvested species and the type of management adopted by the exploiting countries. Single-species management is modeled by using three single-species models of the pelagic complex. Net present value is increased by over 20% when applying multispecies management in the cooperative case. Under non-cooperation there is always overfishing of all species compared to the global optimum, resulting in depletion of the mackerel stock and an almost 50% loss in net present value attainable from the aggregate fishery. Interestingly, under non-cooperation the effect of exploiters applying either single-species or multispecies management is rather small on the health of the stocks and on economic benefits. [ABSTRACT FROM AUTHOR]

Life Cycle Assessment and Data Envelopment Analysis have been repeatedly combined in the literature as LCA+DEA method with the aim of enhancing the utility of life-cycle based methods in order to account for eco-efficiency verification and environmental impact minimization. Despite its evolution through time, it lacks specific standards that norm the combination of the two methods. In this sense, this study noted that its development has evolved in the frame of mainstream cultural perspectives to measure environmental impacts (i.e., hierarchist approaches). Therefore, the main objective of the study is to compare the benchmarking results obtained through DEA computation using different Cultural Theory approaches to calculate environmental impacts. For this, a case study for the Cantabrian purse seining fishing fleet was chosen. Hence, three different DEA matrices were constructed attending to the three main human visions on environmental issues: hierarchist, individualist and egalitarian. All three matrices represented the same set of inputs to be optimized, but differed in the nature of the output flow, representing landed fish, energy content or biomass removal. Results suggest that optimization of environmental impacts is strongly influenced by the cultural perspective selected. In the particular case of fishing fleets, benchmarking environmental impacts based on anthropocentric views may be ignoring the health of fishing stocks and the trophic complexity of the ecosystems. Methodological conclusions are directed towards the need to define more flexible and holistic frameworks in LCA+DEA modelling with the aim of enrichening the set of predetermined assumptions, including the Cultural Theory, to avoid biased interpretations. [ABSTRACT FROM AUTHOR]

How important are coral reefs for food security and to what extent does coral reef conservation contribute to the food security of the coastal communities in the Coral Triangle? Based on the national fish production and consumption data from the Philippines and some data from Indonesia, Clifton and Foale (2017) [12] argued that the pelagic fisheries are far more important than coral reef fisheries for the food security of the Philippines and Indonesia. While it is true that, in totality, populations in both the Philippines and Indonesia rely heavily on pelagic fisheries for animal protein, this commentary demonstrates that coral reef fisheries contribute substantially to the food and livelihood security of coastal communities, which make up the poorest and most food insecure sector of the economy. There is also significant growth potential in nearshore fisheries that can be captured by working to recover currently degraded coral reef ecosystems. Nonetheless, research and institutional reforms in all sources of fish protein (pelagic, demersal, and aquaculture) are urgently needed to improve not only food security but also the lives and livelihoods of coastal fishing households in the Coral Triangle. [ABSTRACT FROM AUTHOR]

Purpose: The main purpose of this article is to assess the environmental impacts associated with the fishing operations related to European anchovy fishing in Cantabria (northern Spain) under a life cycle approach.Methods: The life cycle assessment (LCA) methodology was applied for this case study including construction, maintenance, use, and end of life of the vessels. The functional unit used was 1 kg of landed round anchovy at port. Inventory data were collected for the main inputs and outputs of 32 vessels, representing a majority of vessels in the fleet.Results and discussion: Results indicated, in a similar line to what is reported in the literature, that the production, transportation, and use of diesel were the main environmental hot spots in conventional impact categories. Moreover, in this case, the production and transportation of seine nets was also relevant. Impacts linked to greenhouse gas (GHG) emissions suggest that emissions were in the upper range for fishing species captured with seine nets and the value of global warming potential (GWP) was 1.44 kg CO2 eq per functional unit. The ecotoxicity impacts were mainly due to the emissions of antifouling substances to the ocean. Regarding fishery-specific categories, many were discarded given the lack of detailed stock assessments for this fishery. Hence, only the biotic resource use category was computed, demonstrating that the ecosystems’ effort to sustain the fishery is relatively low.Conclusions: The use of the LCA methodology allowed identifying the main environmental hot spots of the purse seining fleet targeting European anchovy in Cantabria. Individualized results per port or per vessel suggested that there are significant differences in GHG emissions between groups. In addition, fuel use is high when compared to similar fisheries. Therefore, research needs to be undertaken to identify why fuel use is so high, particularly if it is related to biomass and fisheries management or if skipper decisions could play a role. [ABSTRACT FROM AUTHOR]

The blue shark ( Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394 cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south-east off South Africa and Namibia, in the south-west off southern Brazil and Uruguay, and in the north-east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north-east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south-west Indian Ocean off South Africa, and in the south-east off south-western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species. [ABSTRACT FROM AUTHOR]

In the last century, the growing evidence that global fisheries are depleting natural resources much faster than they can recover has led to negative processes, like overfishing, being addressed with increasingly complex models and thus mitigating or regulating actions that aim to protect stocks. Said negative processes contain two components: (i) they can diminish the reproductive potential of fish stocks, called over exploitation by recruitment, and (ii) the effect of early capture prevents the full realization of the growth potential, called overfishing by growth. In this article, the structure of common sardine sizes is analyzed. Due to the precise moment in which pre-recruits are incorporated into the exploited phase of the stock is unknown, the estimation of a recruitment size is a hard problem. This problem is addressed by modeling the mean size via a stochastic process, applying models of structural change. A time series (2001–2015) was analyzed on a weekly time scale based on the size structure of the pelagic fishery landings in the central-southern zone of Chile (32∘10′–40∘14′ LS), from the V. to the XIV. Region. Specifically, the evolution of sizes according to macro-zones was studied for the conglomerates identified in two sub-zones, the V.–VIII. and IX.–XIV. Regions. In this context, the reference size for juveniles to cautiously allow the recruitment process of the common sardine from the central-southern zone of Chile was estimated, and the behavior of these sizes was spatially analyzed. Finally, a statistical inferential criterion was established that confirms the mean size of juveniles with a certain margin of error, which allows nonetheless later on to define a fraction that could be protected to avoid overfishing by growth.

While economists have discussed ecosystem-based fisheries management and similar concepts, little attention has been devoted to purposeful modeling of food webs. Models of ecosystems or food webs that make economic analysis viable should capture as much as possible of system structure and dynamics while balancing biological and ecological detail against dimensionality and model complexity. Relevant models need strong, empirical content, but data availability may inhibit modeling efforts. Models are bound to be nonlinear, and model and observational uncertainty should be included. To deal with these issues and to improve modeling of ecosystems or food webs for use in ecosystem-based fisheries management analysis, we suggest the data assimilation method ensemble Kalman filtering. To illustrate the method, we model the dynamics of the main, pelagic species in the Norwegian Sea. In order to reduce parameter dimensionality, the species are modeled to rely on a common carrying capacity. We also take further methodological steps to deal with a still high number of parameters. Our best model captures much of the observed dynamics in the fish stocks while the estimated model error is moderate. [ABSTRACT FROM AUTHOR]

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Isolation can provide marine ecosystems with a refuge from human impacts. However, information on the biodiversity, ecology and fisheries of remote regions is often sparse. The proposed Coral Sea Marine Reserve could create one of the world's largest and most remote marine parks, yet little information is available to inform discussions. Fish captures from the Coral Sea and adjacent Great Barrier Reef (GBR) were assessed from reports contained in a chronology of spearfishing publications from 1953 to 2009, and reveal for the first time the history of recreational spearfishing in the Coral Sea. Although the area is perceived as relatively untouched, the data indicate that spearfishers have frequented Coral Sea reefs for at least 43 years and reported captures have increased exponentially. Post-1993 trophy captures in the Coral Sea (mean 23 kg) were larger than the adjacent GBR (9 kg). Reef species characterize the GBR catch, while large pelagic species characterize the Coral Sea catch. Provided that functionally important fishes are not targeted, the relatively small scale of recreational spearfishing and the focus on pelagic species suggests that spearfishing currently exerts limited pressure on the ecology of Coral Sea reefs. [ABSTRACT FROM PUBLISHER]

A work of gathering historical fishing (catch, fishing effort, CPUE, characteristics and operation of purseiner fleet) and satellite (NOAA, SeaStar and SeaWind) database of northern Chile, and fishing and oceanographic in situ sampling for validation purpose is made. With this information and the use of geographical information system (GIS) the distribution of pelagic resources and the associated environmental conditions (sea surface temperature, thermal gradients, chlorophyll concentration and wind fields) are analysed in order to develop a probable fishing ground (PFG) index prediction model. A PFG model of anchovy (Engraulins ringens) is operative for the northern Chile. The impact of the use of PFG charts was evaluated analyzing the operational efficiency of the involved purse seiner fleet. An availability index, independent from the present fishery activity, is estimated from the PFG index and images that depend on historical and present environmental conditions and historical catches. The management measures that assure the resources sustainability are present

During the past three decades considerable changes have taken place within the Icelandic pelagic industry which, previously considered rather fragmented, is now a highly concentrated vertically integrated industry due to considerable consolidations of quotas. During this period, changes in the ecosystem around Iceland have also brought valuable pelagic species such as Atlanto-Scandian herring and Atlantic mackerel to the EEZ, while other species such as capelin have declined. Part of the concentration within the pelagic sector can be attributed to changes in the ITQ management system and company adjustments to laws and regulations. Another aspect can be attributed to the entrance of valuable species into the Icelandic EEZ and decreasing quotas of fishmeal oriented species. Finally technology changes have increased production efficiency in processing and fisheries. All this has altered the Icelandic pelagic industry in three ways: Firstly, processing for human consumption has increased with additional species and advances in processing technology. Secondly, raw material for the fishmeal industry has declined parallel with lower capelin quotas. Thirdly, a number of processing utilities and vessels have been scrapped, affecting employment in many fishing villages. [ABSTRACT FROM AUTHOR]

This study analyses depredation by killer whales (Orcinus orca) and false killer whales (Pseudorca crassidens) on catches of the Uruguayan pelagic longline fishery in the Southwestern Atlantic Ocean between 1998 and 2007. Data were collected by scientific observers from the National Observer Program of the Tuna Fleet operating in the area between 19°-40.5°S and 20°-54°W. Depredation occurred in 67 of the 1029 sets and was restricted to the area from 25°-40.5°S to 27°-53°W, though larger proportions of depredation (DP: percentage of total fish caught damaged by cetaceans) were observed in the Brazil-Malvinas (Falkland) Confluence area (34°-37°S and 51°-53°W) where most of the fishing effort was concentrated. Depredation occurred year-round though intra-annual variability in its intensity was recorded. The overall DP was 0.37% and was slightly higher in autumn. The spatial analysis showed that DP within grids of 1 x 1° was homogeneous and generally <2.5%. Ten out of 57 fish species caught by the fishery were depredated by cetaceans. Swordfish (Xiphias gladius) showed the highest DP per species (1.17%). Using the frequency of resources selectivity index of Ivlev, it was determined that swordfish was selected as a preferred prey in 43.9% of the sets with depredation. Generalized linear models indicated that distance to coast, year, and vessel were significant variables in explaining the number of fish depredated per fishing event. The presence of killer whales in the fishing ground seems not to affect the catch per unit effort by the longline fishery. The losses caused by depredation of cetaceans on the catch are low with probably minor economic effects to the Uruguayan longline fishing industry. [ABSTRACT FROM AUTHOR]

Bycatch is one of the main causes of human-caused mortality and population decline of many marine mammals. Monitoring bycatch is the first step to understand the impact of the fisheries on the species affected. Understanding how the interaction between marine mammals and fishing operations varies in space and time, and how it is influenced by environmental variables, is essential for designing mitigation strategies to reduce bycatch mortality. In this paper, we use data gathered by scientific observers and a fishing skipper to analyse marine mammals bycatch by the Uruguayan pelagic longline fishery operating in the Southwestern Atlantic Ocean from 1996 to 2007. The total bycatch per unit effort (Bcpue) was 0.0150 marine mammals/1000 hooks and the highest values (~0.2) were recorded between 37°-38°S and 49°-51°W. Total cetacean Bcpue during the study period was low (0.0051 cetacean/1000 hooks) and occurred between 32°-37°S and 46°-54°W. Generalized additive models showed that cetaceans' bycatch was mainly affected by the depth, sea surface temperature, and season. Although cetaceans were captured year-round, the highest values were registered in spring months, most bycatch events occurred over the continental slope (median = 619 m) and in waters with a median temperature of 19.7°C. The bycatch of pinnipeds was influenced by depth, location, and season. Pinniped bycatch occurred mainly in winter, in waters ranging from 80 to 5000 m of depth (median = 2366 m) between 34°-37°S (median = 35.9°S) and 54°-49°W (median = 51.8°W). The spatial analysis showed that most bycatch events occurred within the Brazil-Malvinas Confluence zone, an area of high productivity where the pelagic longline fleet concentrates its fishing effort and where marine mammals probably concentrate to feed. [ABSTRACT FROM AUTHOR]

Oceanic top predators are the subject of studies by researchers under the international Climate Impacts on Oceanic Top Predators (CLIOTOP) program. A wide range of data sets have shown that environmental conditions, such as temperature and marine productivity, affect the distribution and biological processes of these species, and thus the activities of the humans that depend on them. In this special issue, 25 papers arising from the 2nd CLIOTOP symposium, held in Noumea, New Caledonia in February 2013 report the importance of realistic physical descriptions of oceanic processes for climate change projections, demonstrate a wide range of predator responses to historical climate variability, describe new analytical approaches for understanding the physiology, behaviour and trophodynamics, and project future distributions for a range of species. Several contributions discuss the implications for conservation and fisheries and show that resolving ecosystem management challenges and conflicts in the face of climate change is possible, but will require attention by decision-makers to issues that are broader than their traditional mandate. In the coming years, an increased focus on the development of management options to reduce the impacts of climate change on top predators and their dependent industries is needed. [ABSTRACT FROM AUTHOR]