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The El Niño Southern Oscillation (ENSO) has a major influence on oceanographic conditions in the Pacific region, which is the primary habitat of skipjack tuna ( Katsuwonus pelamis ). This study investigates the relationship between ENSO dynamics and tuna fisheries in the Central Pacific by using sea surface temperature (SST), mixed layer depth (MLD), and purse seine fishing effort records of skipjack tuna from 2007 to 2015. The focus of this research is to understand how the displacement of the warm pool is associated with the spatial distribution of catch per unit effort (CPUE) of skipjack tuna. The findings show that during the La Niña periods of 2007 - 2008 and 2011, CPUE values in region 2 tended to decline to around 18 - 22 tons per set, while in region 1, they increased up to 30 - 35 tons per set. Conversely, during the El Niño period of 2009 - 2010, CPUE in region 2 remained high at around 27 - 33 tons per set, while region 1 showed more stable conditions. The highest CPUE recorded in mid-2015 during a strong El Niño, reaching approximately 45 tons per set in region 2 and nearly 40 tons per set in region 1. These results indicate that the displacement of the warm pool associated with ENSO impacts the spatial shift of CPUE, where El Niño tends to push fish accumulation toward the eastern Pacific, while La Niña drives it toward the western Pacific.

The North Coast of Central Java is a key location where 12% of Indonesia's anchovy catch, or 23,560 tons, is produced by purse seine fishing. We used the FPIs tool, which has 68 different measures scored from 1 to 5 by experts, to evaluate the environmental, economic, and community performance of the anchovy fishing industry on Java's north coast. The result shows that the community pillar performs relatively better (an average score of 3.6) than the ecology and economy pillars, only 2.63 and 2.68, respectively. This research highlights the overcapacity of the fishery and the decreased trend of the anchovy's abundance index, indicating the fishery's unperformed ecology and economic dimension. This research suggests that despite the fishery's poor ecological and economic performance, the local community's dependence on anchovy resources remains high, as suggested by significant involvement in the fishing and processing of the catch and ownership of most vessels the local fishers possess.

The development of fishing technology, particularly in purse seine, has undergone significant transformation over time, thus requiring a comprehensive analysis of vessel dimensions and the characteristics of the fishing gear used. This study aimed to analyze the characteristics and dimensional relationships of small pelagic purse seine fishing gear and vessels at Pekalongan Archipelago Fishing Port (PPN), Central Java, Indonesia. This study employs a descriptive method, collecting primary data through field observations, measurements, and interviews with fishermen. Eight purse seine vessels, each under 30 GT, were selected from a total population of 84 units using accidental sampling. The analysis focused on vessel dimensions, including length, width, depth, and gross tonnage (GT), and fishing gear parameters, such as body length, rope length, and outer side height. The results show that the sampled vessels have GTs ranging from 20 to 28, with lengths between 18.50 m and 21.35 m, indicating homogeneity in the fleet. The purse seine dimensions varied, with body lengths ranging from 90.00 m to 97.14 m and outer side heights of the bunt between 53.34 m and 64.77 m, suggesting design adaptations for optimizing small pelagic fish catches. The length ratio of the purse seine to the vessel ranged from 21.773 to 23.965, while the height-to-length ratio of the purse seine was between 0.162 and 0.196, indicating adequate dimensions for effective fish encirclement and retention. This study provides insights into the characteristics and optimization of small pelagic purse seine fishing gear and vessels in PPN Pekalongan, contributing to sustainable fisheries management in the region.

Purse seine is one of the active fishing gear that is non-destructive to marine habitats. This fishing gear usually catches schooling fish, especially pelagic fish. The production volume of purse seine catch depends on its productivity value. The productivity of fish catch is determined by the ability of the vessel to obtain the catch. The purpose of this research was to determine the fishing productivity of purse seine fishing gear in Aceh Singkil, Aceh. This research was conducted in May - June 2025, using quantitative descriptive data analysis. Data was obtained through observation and interviews. The primary data collection comes from 4 purse seine vessels with two of them had capacity 16 GT, then 20 GT and 30 GT, while the secondary data is from the Marine and Fisheries Office of Aceh Singkil. Based on the results of the purse seine catch consists of several types of fish, namely Tuna ( Euthynnus affinis ), Horse Mackerel ( Megalaspis cordyla ), Skipjack Tuna ( Katsuwonus pelamis ), Batavian Batfish ( Platax batavianus ), Great Barracuda (Sphyraena barracuda), Bigeye Scad ( Selar crumenophthalmus ). Based on the analysis results, it shows the fish that are caught the most is tuna on 14.893 Kg, horse mackerel on 5.086 Kg, and skipjack tuna on 3.730 kg. Then KM_0005_010 has a high productivity value of 1.759 kg/trip then other. The existence of these differences can be influenced by various factors such as natural codition, fishing seasons, capacity, and the number of trips.

The performance of fishing operations, especially for pelagic fish, is important because these resources are widely used for human food needs and serve as an evaluation material for sustainable fishing operations. This study aims to describe the composition of purse seine catch types, determine the productivity of purse seine fishing, and determine the extent of fishing areas in the waters of Bone Gulf, Sinjai Regency. This research uses a case study method by directly following and describing the conditions of fishing operations and making observations and sampling data directly in the field. Primary data was obtained by making direct observations at the research site by following purse seine fishing operations in August - October 2022. Primary data can also be obtained through the interview method. The species composition of purse seine catches in the waters of Bone Gulf, are Skipjack tuna ( Katsuwonus pelamis ) percentage of catches is 94%, Houndfish ( Tylosurus crocodilus ) 5.6% and Mahi-mahi ( Coryphaena hippurus ) 0.4%. In this study, the average productivity of purse seine fishing during 30 fishing trips was 9.89 kg/min. The purse seine fishing operation pattern shows that the fishing location moves with a relatively short distance and there are three fishing areas determined based on the fishing areas that are close to each other including the first fishing area of 1,450 ha, then for the second fishing area of 181.27 ha while for the third fishing area of 814.17 ha.

The European Standard EN 14757 recommends gillnet mesh sizes that range from 5 to 55mm (knot-to-knot) for the standard monitoring of fish assemblages and suggests adding gillnets with larger mesh sizes if necessary. Our research showed that the recommended range of mesh sizes did not provide a representative picture of fish sizes for larger species that commonly occur in continental Europe.We developed a novel, large mesh gillnet which consists of mesh sizes 70, 90, 110 and 135mm (knot to knot, 10m panels) and assessed its added value for monitoring purposes. From selectivity curves obtained by sampling with single mesh size gillnets (11 mesh sizes 6 – 55mm) and large mesh gillnets, we identified the threshold length of bream (Abramis brama) above which this widespread large species was underestimated by European standard gillnet catches. We tested the European Standard gillnet by comparing its size composition with that obtained during concurrent pelagic trawling and purse seining in a cyprinid-dominated reservoir and found that the European Standard underestimated fish larger than 292mm by 26 times. The inclusion of large mesh gillnets in the sampling design removed this underestimation. We analysed the length-age relationship of bream in the Římov Reservoir, and concluded that catches of bream larger than 292mm and older than five years were seriously underrepresented in European Standard gillnet catches. The Římov Reservoir is a typical cyprinid-dominated water body where the biomass of bream > 292mm formed 70% of the pelagic trawl and purse seine catch. The species-specific relationships between the large mesh gillnet catch and European Standard catch suggested that the presence of carp (Cyprinus carpio), European catfish (Silurus glanis), tench (Tinca tinca) or bream warrants the use of both gillnet types.We suggest extending the gillnet series in the European Standard to avoid misinterpretation of fish community biomass estimates

Aceh waters are an area with abundant fishery resources, where Skipjack tuna ( Katsuwonus pelamis ) is one of the leading commodities. This study aims to assess the optimization of purse seine fishing gear on skipjack tuna catch at the Kutaraja Fishing Port (Type A). The research was conducted in August 2024 using observation and interview methods to collect primary and secondary data. The results showed that skipjack tuna production fluctuated during the 2019-2023 period, with the highest production of 9,704 tons in 2023 and the lowest of 6,103 tons in 2021. The highest fishing effort reached 2,676 trips in 2022, while the lowest was 2,112 trips in 2021. The catch per unit effort (CPUE) value reached 3.69 tons/trip in 2023, indicating that purse seine gear is able to operate optimally in supporting the increase in skipjack tuna catch. Optimization of purse seine gear significantly contributes to skipjack tuna catch at PPS Kutaraja, although production fluctuations are still affected by environmental challenges. Good and ecosystem-based management is needed to maintain the sustainability of skipjack tuna stocks and meet the needs of fishermen and markets.

Tropical tuna support some of the largest and most valuable artisanal and industrial fisheries worldwide, conducted to a large degree with Fish Aggregating Devices (FADs). Yellowfin, bigeye and skipjack are the main tuna species found in mixed aggregations around FADs and they are simultaneously encircled by the purse seining operation. One of the key challenges that purse seine fleets fishing with drifting FADs face in all oceans is to be able to target species in healthy condition such as skipjack, while reducing impacts on bigeye and yellowfin in areas where there is a need to reduce fishing pressure on these species. The present paper explores a technical solution for selective fishing at FADs by means of acoustic equipment used by purse seiners. Acoustic frequency response of skipjack and bigeye tuna were determined at 38, 120 and 200 kHz. Skipjack showed stronger response at higher frequencies. On the contrary, bigeye showed stronger responses at lower frequencies. The robust pattern shown in frequency responses of the two species demonstrates the potential to predict abundance and species proportions based on purely acoustic measures. The paper also addresses the conditions that need to be met to successfully apply this technology for selective fishing as well as other uses of direct acoustic observations to support tuna conservation.

The Indian Ocean Tuna Commission expresses concern over the overfished state and susceptibility to the overfishing of yellowfin tuna ( Thunnus albacares ). Acknowledging the challenges of increased fishing effort in a profitable fishery, our study aims to understand factors influencing French purse seine fishing vessel dynamics. Our primary goal is to assess purse seine vessel utilisation with recent catch limits and compliance with the European Union Common Fisheries Policy, which mandates measures to align fishing capacity with opportunities to sustain fish stocks at maximum sustainable yield (MSY). Using Data Envelopment Analysis, we evaluate the relationship between vessel fishing capacity to catch limits and the MSY reference point for yellowfin tuna. Findings indicate that the French fleet could meet catch limits with approximately 21% fewer vessels if fully utilised and 26% fewer if reduced to meet their equivalent MSY share. Aligning capacity with fishing opportunities is crucial for the profitability and preservation of these essential tuna populations, resulting in more sustainable and economically viable fisheries. Graphical abstract

The escalating impact of anthropogenic activities on global climate patterns necessitates urgent measures to reduce emissions, with the maritime industry playing a pivotal role. This article aims to examine the adoption of International Maritime Organization energy efficiency measures for the often-overlooked fishing vessels and their contribution to the overall maritime decarbonization efforts. The article analyzes the attained technical efficiency indices of a case study large-scale fishing vessel and compares them with those of two cargo ships where IMO measures already apply. To support the proposal, a comprehensive analysis of the energy efficiency indices of eight large purse seine fishing vessels is also presented. The results show that large-scale fishing vessels of 400 GT and above could be subject to the IMO energy efficiency measures. The operational challenges, unique to the fishing sector, suggest that sector-specific considerations may be required to integrate the fishing fleet into the already existing IMO energy efficiency guidelines. Looking ahead, this article explores the benefits of aligning Regulation (EU) 2023/957 and IMO guidelines, as well as applying the IMO Carbon Intensity Indicator (CII) in assessing the operational environmental impact of fishing operations, emphasizing the importance of including these vessels in the current regulatory frameworks to promote decarbonization.