Pelagic Fisheries Research Articles

Coral reefs and small pelagic fisheries: livelihood and governance interactions in Southern Luzon, Philippines

Coral reef fisheries and small pelagic fisheries make different contributions to livelihoods, food and nutrition security, which have informed academic and policy debate about their respective needs for governance. However, few studies have explicitly examined how governance of these different fisheries interacts at a local level, or how they interact with wider social-economic contexts and processes. This study examines a small pelagic fishery in the Philippines, focusing on the varied interactions between this fishery and coral reefs. Drawing on household surveys, focus group discussions and interviews, we demonstrate the significant economic and social contributions made by the small pelagic fishery and describe a series of governance interventions aimed at protecting coral reefs and regulating small pelagics. We highlight some of the emerging governance risks that undermine legitimacy and social acceptance for the management of both small pelagic and coral reef resources. We argue that planning for successful management of fisheries needs to be highly cognizant of the complexity of livelihoods, to equity issues in sharing the benefits and burdens of conservation, and to tourism-fishery interactions.

Efficient tuna detection and counting with improved YOLOv8 and ByteTrack in pelagic fisheries

Efficient tuna detection and counting with improved YOLOv8 and ByteTrack in pelagic fisheries

Bioenergetics modelling approach to evaluate the growth of Indian oil Sardine in the different fishing locations of the Bay of Bengal

ABSTRACT Sardine growth and variability along the Indian East coast have been less studied compared to the West coast and seldom attempted in numerical models. Both coasts exhibit significant differences in physical and chemical properties as well as biological productivity. This study realistically simulated sardine growth along the Indian East Coast with seasonal and spatial variability by using a sardine bioenergetics model. The model comprises a lower trophic level model (NEMURO) and a fish bioenergetics component, which utilises prey densities and temperature derived from NEMURO. After hatching, sardine weight showed a consistent increase from June to February and reached 50–80 g and 75–100 g in Tamil Nadu and Andhra Pradesh, aligning with observed ranges of landing data. Fish weight declined during summer (25–40 g) and further gained from June. Optimum water temperature and high phytoplankton abundance (June-January) favoured sardine growth, while temperature beyond the preferred range and minimal phytoplankton availability (March-May) resulted in weight loss in all locations. Key model parameters influencing sardine growth and its seasonality are discussed in detail. The outcome of this numerical model shows a promising step towards numerical predictions of the Indian East Coast pelagic fishery.

Seasonal effects of extreme climate events and sea surface temperature indicators on the vulnerability of marine pelagic fisheries in the Bay of Bengal region.

Seasonal effects of extreme climate events and sea surface temperature indicators on the vulnerability of marine pelagic fisheries in the Bay of Bengal region.

Climate change and its effects on the marine food web with a concentration on the pelagic fishery in the northern Arabian Sea

Climate change and its effects on the marine food web with a concentration on the pelagic fishery in the northern Arabian Sea

Revealing the adaptation strategies of pelagic fleets in the Bay of Biscay by combining fishery data and fishers’ knowledge

Abstract The French pelagic fishery in the Bay of Biscay is currently facing new challenges. To anticipate and support future adaptations of fishers’ strategies, we proposed to scrutinize fishers’ past behaviours and determine the driving factors of their adaptations using a combination of quantitative and qualitative analysis. Annual strategies deployed by the pelagic fleet between 2010 and 2018 were identified through fishing data. Individual sequences of strategies used by vessels then served as a basis for the definition of a new fleet segmentation, revealing behavioural patterns and bridges between strategies. Fishers from two segments were then interviewed to identify the factors underlying their decisions at four different time scales. Fishers surveyed felt in control of both long-term (pluri-annual) and short-term (daily) decisions. Social aspects and personal preferences were found to be preponderant at these time scales. On the contrary, seasonal and annual activities were perceived as being dictated by market opportunities and ecological cycles. We showed that fishers were forced toward a greater dependence on sardine by regulatory constraints and the lack of opportunities on other species. Our study draws perspective by combining historical fishery data analysis with fisher’s experiential knowledge to understand fishing behaviours.

Beyond the Boundaries: Poleward Range Expansion of the Atlantic Chub Mackerel Scomber colias in SW Atlantic Ocean

ABSTRACTShifts in species distribution have far‐reaching implications across ecological, economic, and social dimensions. Pelagic fish, integral to global fisheries, have displayed notable euryhaline and eurythermal characteristics. However, a poleward range expansion trend has emerged in the northern hemisphere for certain Scomber species since the 2010s, attributed to sea surface temperature and food resource dynamics. Scomber colias, a principal pelagic fishery resource in Argentina, stands as an underexploited species with recent landings totaling approximately 14,800 tons. In the North Patagonian shelf waters, where S. colias resides at its southern distribution, there has been documented ocean warming. In this context, this study evaluates potential changes in the distribution and abundance of S. colias from 1991 to 2022 in the Southwestern Atlantic Ocean (SAO). Drawing on two distinct data sources, the analysis reveals a poleward range expansion, extending to 48°5′S, exceeding historical limits by 278 km. This expansion is positively correlated with rising sea surface temperatures, with the most significant displacement observed during summer, when this species has a high feeding activity in the study area. The investigation further explores the relationship between S. colias presence and the abundance of its primary prey species between 2011 and 2022. This is highly possible, yet no significant results were uncovered. This study marks the first documented southward range expansion of S. colias in the SAO, providing essential quantitative insights for biological studies, fisheries management, and the canning manufacturing industry. The latter could benefit from year‐round access to fish, potentially generating employment opportunities and fostering economic growth within the local community.

ANALYSIS Catch Per Unit Effort (CPUE) AND Maimum Sustainable Yield (MSY) MALE MACKEREL (Rastrelliger kanagurta) FLYING IN THE SAMUDERA FISHING LAND (PPS) KENDARI

The Banda Sea is an Indonesian water body that holds potential for small pelagic fisheries resources. Situated between Sulawesi Island and Maluku, it is part of the Fisheries Management Area Of The Republic Of Indonesia (WPP-NRI 714), Male mackerel (Rastrelliger kanagurta) is one of the fish species with high economic value, greatly favored by the community for consumption. This has led to an increase in its capture rates. Therefore, the research aims to determine the CPUE and MSY of Indian mackerel in the Kendari Ocean Fisheries Port. Data collection was conducted at the Kendari Ocean Fisheries Port from logbooks, and the research lasted from November to December 2023. The results showed that the standard fishing gear used to catch these fish is purse seine. The status of the utilization of the fishery resources is said to be experiencing underfishing. Based on the research results, the maximum sustainable yield (MSY) is 96,386 kg/year, with an optimal fishing effort of 2,300 trips/year (Fox model).

A multidecadal study of the Malabar upwelling system influencing Indian Mackerel landings along the coasts of Karnataka and Kerala, south-east Arabian Sea

A multidecadal study of the Malabar upwelling system influencing Indian Mackerel landings along the coasts of Karnataka and Kerala, south-east Arabian Sea

Which Novel Ingredient Should be Considered the “Holy Grail” for Sustainable Production of Finfish Aquafeeds?

ABSTRACTThe immense production of fishmeal and fish oil is dramatically intensifying the severe state of pelagic fisheries overexploitation. The latter in conjunction with the increasing demand for low‐cost protein‐rich food supply prompt aquaculture to employ new practice. Several novel dietary ingredients are currently under evaluation for potential incorporation in aquafeeds in an effort to shift the aquaculture sector toward a more sustainable and economic production. The present review aims to summarize the existing findings regarding the effects of studied alternatives to fishmeal and fish oil on the most valuable and commercially produced marine (Sparus aurata and Dicentrarchus labrax) and freshwater (Salmo salar and Oncorhynchus mykiss) finfish species in European aquaculture. Alternative protein sources, including macroalage (marine plants), krill (marine fishery), insects (terrestrial), terrestrial animal by‐products (processed/rendered), and single cell ingredient (biotechnology), are discussed for their efficiency in promoting the growth and the welfare of both fry and adult cultured finfish species. Applicability of these ingredients is reviewed in terms of nutrient composition, dietary inclusion level, performance output, digestibility, and health benefits. In addition, a meta‐analysis was conducted based on data from peer‐reviewed scientific publications in order to assess whether novel ingredients meet the dietary protein (amino acid) and lipid requirements of finfishes. Aquafeed reformulation strategies should ensure the recommended daily nutritional requirements and additionally indicate the meta‐analysis alternatives, such as microalgae, which are deficient in essential amino acids. The sustainable expansion of aquaculture is on the horizon, but which novel ingredients may be regarded as the key drivers to its establishment?

The review of the evolution, deficiencies, and future outlook of China's pelagic fisheries management from 1985 to 2024

The review of the evolution, deficiencies, and future outlook of China's pelagic fisheries management from 1985 to 2024

Assessments of 12 Commercial Species Stocks in a Subtropical Upwelling Ecosystem Using the CMSY and BSM Methods

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.

Climate risk assessment of the fisheries in Namibia

In Namibia, fisheries are important for food security and protein provisioning, income generation and trade; but they are vulnerable to the impacts of climate change. Not only does climate change impact the marine living resources crucial to fisheries; but changes in weather, currents and storminess are affecting the safety and effectiveness of fishing. Here we ask: What are the key risks from climate change to the eight large-scale fishery sectors of Namibia, and for the recreational and small-scale (artisanal) fisheries? For each fishery sector, we assessed three main risk components: (1) climate hazard exposure; (2) fish species sensitivity; and (3) socio-economic vulnerability. In combination, these three risk components are then used to calculate the overall climate risk for each fishery. Climate hazard exposure was assessed as highest for the small-scale, recreational, and rock lobster fisheries. Species sensitivities were highest for the rock lobster and crab fisheries, followed by monkfish trawlers, hake liners and hake trawlers. Socio-economic vulnerability was highest for the small pelagic fishery (linked to the collapse of pilchard). The overall climate risk emerged as greatest for the rock lobster fishery, followed by the (highly marginalised) small-scale artisanal fishery. The key risks by sector emerging from this assessment, informed five stakeholder workshops held across Namibia in 2023, attended by representatives of each sector and aimed at exploring options for climate adaptation. Based on these, we discuss potential adaptation measures that could reduce risk and minimise consequences, in support of improved climate resilience in Namibian fisheries.

Small pelagic fish: new frontiers in science and sustainable management

Small pelagic fishes occupy an important trophic role in every global aquatic ecosystem, and many species are heavily exploited by fisheries, including some of the largest and most valuable capture fisheries in the world. In November 2022, a symposium on small pelagic fish titled “ Small Pelagic Fish: New Frontiers in Science and Sustainable Management” was cohosted by PICES, ICES, and FAO in Lisbon, Portugal. This special issue contains a collection of research manuscripts that explore approaches currently being used and developed to assess and manage small pelagic fishes. In particular, this issue covers topics on novel approaches to surveying small pelagic fishes, incorporating environmental covariates into management, management strategy evaluation, and aspects of the economics of small pelagic fisheries. The conclusions highlight the importance of new approaches that seek to enhance small pelagic fish surveys and ecosystem monitoring, incorporate that ecosystem information into management strategy evaluation, and predict the potential impacts of ecosystem changes on outcomes for economies and communities that rely on sustainable populations of small pelagic fishes.

Habitat Prediction of Bigeye Tuna Based on Multi-Feature Fusion of Heterogenous Remote-Sensing Data

Accurate habitat prediction of Bigeye Tuna, the main fishing target of tuna pelagic fishery, is of great significance to the fishing operation. In response to the fact that most of the current studies use single-source data for habitat prediction, and the association between spatiotemporal features and habitat distribution is not fully explored and that this has limited the further improvement of prediction accuracy, this paper analyzes the spatiotemporal distribution of the characteristics of Bigeye Tuna’s highly migratory nature. Additionally, it puts forward a method of habitat prediction that utilizes heterosource remote-sensing data for the four-dimensional time–space–environment–spectrum (TSES) for deep-level feature extraction. First, a multi-source heterogeneous dataset was constructed by combining the spatiotemporal distribution characteristics of the product-level environmental remote-sensing data and the L1B-level original spectral remote-sensing data, and then a multi-branch, dynamic spatiotemporal feature extraction, Long Short-Term Memory Network (LSTM) time-series model was constructed to extract the characteristics of the heterogeneous data. This model was constructed to fully explore and utilize the multidimensional deep-level TSES distribution features affecting the habitat prediction. Finally, the two types of heterogeneous data were subjected to the weighted average-based decision-level fusion to obtain the final prediction results. The experimental results show that compared with other methods, the proposed method in this paper outperforms traditional machine-learning models and other single-source, data-based time-series models, with R2 reaching 0.96278 and RMSE decreasing to 0.031361 in the validation experiments of these models. In contrast, the method in this paper demonstrates good generalization ability and achieves accurate prediction of future fishery distribution.

Investigating the effects of pelagic trawling on the welfare of Atlantic herring (Clupea harengus)

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.

Growth parameters of the clupeids Limnothrissa miodon and Stolothrissa tanganicae in northern Lake Tanganyika (Bujumbura sub-basin)

The analysis of growth parameters in fish stocks, such as the asymptotic length (L∞) and the curvature parameter (K), is crucial for the estimation of production rates and total mortality rates in fisheries management. Here, we estimated the growth parameters of the clupeids Limnothrissa miodon and Stolothrissa tanganicae in the northern part of Lake Tanganyika (Bujumbura sub-basin). Both species are important targets of pelagic fisheries, but the available estimates are based on scarce size frequency data, and rarely on size as a function of age data. We provide new estimates of L∞ and K based on size as a function of age data, with age being inferred from otolith weights. Furthermore, we reanalyze several existing length frequency datasets using advanced statistical procedures to test if growth parameters estimated by length frequency analysis are consistent with those obtained from size as a function of age. We found that length frequency analysis consistently underestimates L∞ and overestimates K as compared to length-at-age data. We recommend that length-at-age data are collected at a much broader spatial and temporal scale than currently available to advance our understanding of the growth dynamics of these two sardine species. This will improve the assessment of stock productivity of Lake Tanganyika’s pelagic fisheries and the conservation of these economically important fish species.

Century‐scale loss and change in the fishes and fisheries of a temperate marine ecosystem revealed by qualitative historical sources

AbstractPolicies aiming to restore ecosystems, achieve thriving fisheries and reverse biodiversity loss require knowledge of their former status and long‐term variation. As quantitative fish data is typically only available for recent decades long after changes may have occurred, a greater use of qualitative sources has been encouraged in marine historical ecology. We examined diverse historical information (including maritime history, fisheries reports, naturalists' accounts, recipes, nautical charts and newspapers) across a multi‐century time span (13th–20th century) for a wide range of species to document their long‐term trajectories in an understudied Northeast Atlantic ecosystem (Irish Sea coast of Wales). We find strong evidence of the loss of both a pelagic fishery for herring, which was of fundamental socio‐ecological importance since at least the 13th century, and the loss of significant multi‐species demersal and intertidal fisheries. Local, commercial and/or functional extinction has occurred for taxa spanning a wide range of diversity (crustacean, elasmobranchs, sturgeon, and teleosts), body size and ecological role, suggesting far‐reaching changes to food webs. This raises fundamental questions about the present‐day health and integrity of this coastal ecosystem and the long‐term viability of current fisheries which depend on a few shellfish species. Our century‐scale synthesis of qualitative data for multiple taxa allows the collective breadth of losses to be fully appreciated and may reduce the risk of ‘shifting baselines’. Restoration to historical baselines may not be achievable, but our findings provide evidence of long‐term change relevant to policies for recovery, and prevention of further decline of fishes, fisheries and ecosystems.

OPERATION TECHNIQUE AND OPERATIONAL TIME CALCULATION OF PURSE SEINE IN FISH CAPTURE: A CASE STUDY ON KM. MUTIARA SEJATI

A purse seine is an active fishing gear operated by encircling schools of fish. KM. Mutiara Sejati is one of the fishing vessels based in PPP Bajomulyo, Central Java, employing purse seine for small pelagic fisheries. That research aimed to explore the operational techniques of purse seine fishing gear and determine the time calculation for its operation. The study was conducted over five months, from October 2022 to March 2023, utilizing observation, interviews, and documentation as research methods. The operational area of the vessel was in the WPP 712 (Java Sea) with PPP Bajomulyo serving as the fishing base. Based on the research findings, the operational process of small pelagic purse seine began with a series of steps, including the deployment of fish aggregating devices, activation of vessel lights, deactivation of lights except for those at the stern, lowering of the boom lights, total shutdown of vessel lights, setting of the net, purse line retrieval, retrieval of the boom lights, net hauling process, catch retrieval, and ultimately, the re-arrangement of fishing gear. Calculation results indicated that the average operational time for the fishing gear during the nighttime was 87 minutes, while during the early morning hours, it was 83 minutes.

Spatial characterisation and drivers of catch and effort in highly specialised recreational pelagic fisheries

Large pelagic finfish are highly mobile, distributed across broad geographical scales, and often targeted by both commercial and recreational sectors. Fishing effort in these fisheries is variable due to seasonal patterns in fish behaviour and accessibility of fishing locations. Similarly, fisher behaviour and access are likely to differ within the recreational sector, between private boat-based fishing and charter (or for hire) fishing. Here, we compare spatio-temporal patterns in catch per unit effort (CPUE), effort (boat days) and catch (total catch per fishing party) for private boat-based and charter fishing, and identify environmental variables that may influence those patterns, for two pelagic species (the tropical narrow-barred Spanish mackerel and temperate Samson fish) in Western Australia. Spatial and temporal patterns of CPUE were investigated using geostatistical indices, such as the global and local index of collocation which compares the spatial distribution of CPUE locations across years and CPUE values at common locations respectively, and the centre of gravity which calculates the mean fishing location weighted by CPUE, along with the influence of environmental variables (including rainfall and sea surface temperature) on catch using generalised additive models (GAMs). The global index of collocation showed consistency in spatial distribution of CPUE and effort between private boat-based and charter fishing for both species. In contrast, the local index of collocation showed differences in the ranges of CPUE and effort within common locations. Private boat-based fishing often occurred close to the coast and adjacent to population centres, while charter fishing occurred further offshore. Spatial shifts over time were more prominent for Spanish mackerel with an overall northerly shift. For private boat-based fishing, higher catches of Spanish mackerel were associated with higher rainfall, along with an increase in ambient air temperature. For charter fishing, higher catches of Spanish mackerel occurred with ambient air temperatures of around 30 degrees Celsius and a decrease in rainfall, where high catches of Samson fish were associated with a decrease in sea surface temperatures and austral winter months. This study highlights changes in the distributions of pelagic species over time and the potential to incorporate spatio-temporal monitoring of recreational harvest into fisheries management.