Search Results (122)

Traditional single-species fisheries management has proven inadequate for capturing ecosystem interactions, leading to a shift toward ecosystem-based approaches. In Korea, diverse small- and medium-scale with varying gear types, production volumes, and practices require management tools that address both ecological and industrial needs. This study developed a Gear-based Fisheries Management Index (GFMI) for 24 coastal and offshore fisheries in Korea. The framework, based on the “ideal gear attributes” defined by ICES, is structured around three objectives: gear controllability, environmental sustainability, and operational functionality. Sub-indicators and weights were derived through expert consultation using the Analytic Hierarchy Process and standardized with Z-scores from national statistics, including production volume, license numbers, and accident rates. Results show that in coastal fisheries, coastal gillnets (61.7) and coastal improved stow nets (60.7) recorded the highest scores, largely due to negative impacts such as bycatch, reproductive capacity, and gear loss. Coastal purse seines (40.9) received the lowest score, reflecting species selectivity advantages. In offshore fisheries, large bottom pair trawls (71.8) and Southwestern medium-size bottom pair trawl (69.3) ranked highest, indicating strong habitat impacts. While coastal improved stow nets, large purse seines, and large trawls performed well in operational functionality, high costs and efficiency constraints remain key vulnerabilities. Full article

The waters surrounding the Five West Sea Islands of South Korea are ecologically important but challenging to survey due to their location within a strategic military zone, strong tidal currents, and significant tidal variation. To assess the fish community in this region, we conducted Korea’s first parallel investigation combining traditional bottom trawl surveys with environmental DNA (eDNA) metabarcoding. Sampling was performed at 10 stations in March, May, and August 2023, and the relationship between fish species occurrence and environmental variables (water temperature, salinity, and depth) was examined. Dominant trawl-caught species included Engraulis japonicus, Johnius grypotus, Coilia nasus, and Okamejei kenojei, each showing seasonal migration and spawning patterns associated with temperature changes. eDNA analysis detected nine additional species absent from trawl catches, such as Ilisha elongata and Thamnaconus modestus, demonstrating its sensitivity in identifying both migratory and sedentary taxa. Our findings confirm that eDNA surveys can complement traditional sampling, improving biodiversity assessment in regions with limited accessibility and complex oceanographic conditions. Full article

Palaemon gravieri is an ecologically important shrimp species that plays a vital role in depressing jellyfish blooms in the southern Yellow and East China Seas of China. However, information on its distribution pattern and migration route related to environmental variables is fragmented. We conducted independent trawling surveys of P. gravieri between 2018 and 2019. Its sea surface temperature and sea surface salinity lower limits were 8 °C and 30‰, respectively. It showed the highest abundance at sea bottom temperatures and salinities of 12–14 °C and 32–33‰, respectively, in spring; 11–12 °C and 32.5‰ in autumn; and 10.5–14 °C and 31–33‰ in winter. Mean biomass, abundance, and size were ranked seasonally as follows: autumn > winter > spring > summer; autumn > winter and spring; and summer > spring > autumn > winter, respectively. Under the current climate scenario, P. gravieri is mainly concentrated in the inshore areas of the southern Yellow and northern East China Seas. Under SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios in 2100, P. gravieri was mainly concentrated in the southern Yellow and northern East China Seas, and in inshore areas of the East China Sea. This species is therefore expected to benefit from climate warming. The findings of this study can facilitate the development of climate-induced fishery strategies and management schemes. Full article

Assessing fishery resources is crucial for sustainable marine ecosystem management and the operation of fisheries. This study integrates trawl surveys, environmental DNA (eDNA) analysis, and scientific echo sounder techniques to analyze the fishery resource distribution of and seasonal variations in the East China Sea. Surveys were conducted in April, July, August, and November 2022, utilizing bottom trawl sampling, eDNA metabarcoding, and acoustic data collection. The results revealed temporal differences in species composition, with crustaceans dominating in terms of abundance and fish species in biomass. The integration of eDNA analysis provided broader species detection, including cryptic and pelagic species, while acoustic techniques enabled large-scale resource assessment. However, discrepancies between methods highlighted the need for methodological refinement. Dominant species exhibited seasonal variation, with Portunus trituberculatus prevailing in spring (April), Trachurus japonicus and Scomber japonicus in summer (July–August), and Pampus argenteus in late autumn (November). A comparative analysis revealed that eDNA is sensitive to pelagic and cryptic species, trawl surveys effectively detect demersal fish, and acoustics allow for broad-scale biomass estimation, highlighting the complementary value of method integration. Full article

The slender snipe eel Nemichthys scolopaceus Richardson, 1848 is cosmopolitan in tropical and temperate seas, inhabiting the mesopelagic and bathypelagic zone between 200 and 1000 m depth. It is known to be an active predator in the DSL (Deep Scattering Layer) and the NBA (Near Bottom Aggregation), feeding mostly on decapod and euphausiid crustaceans, and playing a central role in carbon fluxes through meso- and bathypelagic ecosystems. Despite its potential importance in the deep trophic web ecosystem, the trophic ecology of Nemichthys scolopaceus is not well known. The aim of this study was to start to fill this knowledge gap. A total of 35 specimens of N. scolopaceus caught through bottom trawling in the Mediterranean Sea were analyzed in the laboratory for stomach content composition. As expected, mainly decapod crustaceans were found, in particular Plesionika martia, Pasiphaea multidentata, Funchalia woodwardi, and Robustosergia robusta species. The degree of digestion of prey in the stomachs was high in all cases. Our findings seem to confirm the specialist diet of Nemichthys scolopaceus based on shrimp-like crustaceans. Full article

Posidonia oceanica seagrass, endemic to the Mediterranean Sea, provides ecological goods and ecosystem services of paramount importance. In shallow and sheltered bays, P. oceanica meadows can reach the sea surface, with leaf tips slightly emerging, forming fringing and barrier reefs. During the 20th century, P. oceanica declined conspicuously in the vicinity of large ports and urbanized areas, particularly in the north-western Mediterranean. The main causes of decline are land reclamation, anchoring, bottom trawling, turbidity and pollution. Artificial sand nourishment of beaches has also been called into question, with sand flowing into the sea, burying and destroying neighbouring meadows. A fringing reef of P. oceanica, located at Saint-Mandrier-sur-Mer, near the port of Toulon (Provence, France), is severely degraded. Analysis of aerial photos shows that, since the beginning of the 2000s, it has remained stable in some parts or continued to decline in others. This contrasts with the trend towards recovery, observed in France, thanks to e.g., the legally protected status of P. oceanica, and the reduction of pollution and coastal developments. The sand nourishment of the study beach, renewed every year, with the sand being washed or blown very quickly (within a few months) from the beach into the sea, burying the P. oceanica meadow, seems the most likely explanation. Other factors, such as pollution, trampling by beachgoers and overgrazing, may also play a role in the decline. Full article

Dense aggregations of species in the family Pinnidae give soft substrata a specific characterization. They may influence the biological and physical properties of the surrounding sediments. Bottom-trawl samplings performed in the Sea of Marmara revealed populations of a large pinnid species, particularly at depths of 40–45 m in soft substrata. Both morphological and DNA analyses confirmed the species’ taxonomic identity as Atrina fragilis. This species had a population density ranging from 31 to 469 ind.km⁻², and the shell lengths ranged from 21.3 to 31 cm. A total of 47 macrozoobenthic species belonging to eight taxonomic groups were found on the shells of ten live and nine dead A. fragilis individuals. Polychaeta accounted for 53% of the total number of species and 75% of the total number of individuals. Among these species, Protula tubularia and Serpula concharum comprised almost 30% of all epifaunal populations. Community parameters changed according to the shell length and width. Different faunal assemblages were encountered on the shells. Given the ecological significance of A. fragilis as both a habitat-forming and sensitive benthic species, conservation measures should prioritize the protection of known habitats and the regulation of activities that lead to seabed disturbance. Full article

To accurately assess the water quality, ecosystem status, distribution of large benthic organisms, and ecological restoration under human intervention, an analysis of benthic organisms on Caofeidian in September and November 2023 and January and May of the following year was conducted in this work. By performing CCA (canonical correspondence analysis) and cluster and correlation coefficient (Pearson) analyses, the temporal variation characteristics of benthic abundance, dominant species, community structure and biodiversity were analyzed. A total of 79 species of macro-benthic animals were found in four months, including 32 species of polychaetes, cnidarians, 1 species of Nemertean, 19 species of crustaceans, and 24 species of molluscs. The use of conventional grab-type mud collectors revealed that the Musculus senhousei dominated the survey (Y > 0.02). While only a small number of Ruditapes philippinarum were collected from bottom-dwelling species, a certain number of bottom-dwelling species (Ruditapes philippinarum and Scapharca subcrenata) were also collected during the trawl survey. Additionally, a significant population of Rapana venosa was found in the area. It is speculated that the dual effects of predation and competition are likely the primary reasons for the relatively low abundance of bottom-dwelling species. The density and biomass of macro-benthos were consistent over time, which was the highest in May, the second highest in January, and the lowest in September and November. The main environmental factors affecting the large benthic communities in the surveyed sea areas were pH, DO, NO₂⁻-N, T, SAL and PO₄³⁻-P. Combined with historical data, it was found that although the environmental condition in the Caofeidian sea area has improved, the Musculus senhousei has been dominant. In addition, the abundance of other species is much less than that of the Musculus senhousei, and the diversity of the benthic community is still reduced. Our work provides valuable data support for the management and improvement of bottom Marine pasture and promotes the transformation of Marine resources from resource plunder to a sustainable resource. Full article

This study reports the first record of Lyconus brachycolus in Spanish waters. A single specimen measuring 216 mm in total length was captured on 13 October 2024 in the Cantabrian Sea (north of Spain, 43.8467 N, −6.2109 W) by bottom trawl at a depth of 412 m. A detailed morphological description, updated characteristics, and illustrations are provided. For comparative purposes, an update of the species’ morphological characteristics was carried out. In an integrative taxonomic approach, the DNA barcode was obtained, which confirmed the morphological identification of the specimen as Lyconus brachycolus. A molecular taxonomic analysis using this marker showed the existence of two clades separated by 5.1%, corresponding to Lyconus brachycolus and Lyconus pinnatus, the two currently valid species of the genus. Full article

For successful economic management of cephalopod fisheries, short-lived squid with a 1-year life span require stock assessment over a short timescale, accompanied by both in-season and real-time stock management. However, insufficient information is available about the dynamic distribution patterns of the squid Uroteuthis duvauceli, Uroteuthis edulis, Loliolus sumatrensis, and Loliolus japonica in China. Such information is vital for establishing a sustainable fisheries management system. In this study, seasonal fishery-independent bottom-trawling surveys were performed from 2018 to 2019 in the southern Yellow and East China Seas to assess the seasonal changes in the distribution of these species. Most U. duvauceli occurred at sea bottom temperatures (SBTs) of 24.52–26.96 °C and sea bottom salinity (SBS) of 30.2–31.54‰ during the summer and at 20.02–22.75 °C and 33.46–34.22‰ during the autumn. Most U. edulis occurred at an SBT of 18.29–19.61 °C and SBS 34.78–35.08‰ during the spring, at 18.63–19.43 °C and 34.43–34.66‰ during the summer, at 8.78–21.81 °C and 34.39–34.77‰ during the autumn, and at 17.90–21.55 °C and 34.34–34.61‰ during the winter. Overall, most L. sumatrensis occurred at 21.00–23.15 °C and 34.11–34.50‰ in autumn. U. duvauceli concentrated in the fishing grounds of Zhoushan during the spring, Lvsi and Zhoushan-Changjiangkou during the summer, Zhoushan and Yushan-Mindong during the autumn, and Wentai-Yushan during the winter. L. sumatrensis mainly occurred in the fishing grounds of Dasha, Changjiangkou-Zhoushan, and Mindong during the summer, Yushan during the autumn, and nearshore areas during the winter. Most L. japonica occurred in the fishing grounds of Haizhou Bay and Zhoushan-Yushan during the spring, Haizhou Bay during the summer, Lvsi during the autumn, and Haizhou Bay during the winter. Our results will be useful for determining the total allowable catch from squid fisheries in these areas in China. Full article

The Eastern Aegean Sea hosts a diverse assemblage of elasmobranchs, many of which are vulnerable or endangered. This study presents a fishery-independent assessment of species composition, catch characteristics, and spatial patterns in bottom trawl fisheries between Lesvos Island and Ayvalik. A total of 48 surveys were conducted between September 2022 and October 2024, identifying nine elasmobranch species, with Scyliorhinus canicula (small-spotted catshark) and Mustelus mustelus (common smooth-hound) dominating the catch. Biological parameters, sex ratios, and condition upon capture and release were recorded, while catch per unit effort (CPUE) and diversity indices were used to evaluate temporal patterns. The survival probability was negatively affected by the trawl duration and elevated temperatures, emphasizing the need for mitigation measures. Spatial models revealed high-density zones that likely function as foraging or nursery grounds. Seasonal shifts in community composition were also evident. Many non-commercial species were discarded irrespective of their size or condition. These findings underscore the ecological importance of this understudied region and support the need for spatially explicit, species-specific management strategies, including gear selectivity improvements, seasonal closures, and Electronic Monitoring. The study offers a critical baseline for enhancing the sustainability of elasmobranch populations in the Eastern Mediterranean. Full article

Deep-sea trawling in the Mediterranean Sea, while economically significant, has profound ecological implications due to high discard rates and the practice’s impact on deep-sea biodiversity. This study examines the composition of discards and bycatch in Antalya Bay, a key deep-sea fishing area in the Eastern Mediterranean, during a commercial fishing season, focusing on seasonal and depth-related variations. Data were collected from deep-sea bottom trawl operations conducted between September 2016 and April 2017, analyzing species diversity and catch composition in terms of discarded and bycatch species. The results revealed an average discard rate of 70.7% of the total catch, with significant seasonal fluctuations. In total, 75 species were identified, comprising 48 Osteichthyes, 11 Elasmobranchii, 10 Crustacea, 4 Mollusca, 1 Brachiopoda, and 1 Echinodermata. Discarded species primarily consisted of juveniles of commercially valuable species (Merluccius merluccius and Lepidorhombus whiffiagonis), endangered elasmobranchs, and non-target benthic invertebrates. Depth-stratified analysis indicated that higher discard ratios and greater biodiversity loss occur at depths between 200 and 700 m, where slow-growing species and vulnerable deep-sea assemblages dominate. CPUE estimates for target, bycatch, and discarded species were calculated as 72.26, 145.12, and 385.52 kg/h, and CPUA values were calculated as 0.79, 1.59, and 2.92, respectively. These findings underscore the disproportionate impact of bottom trawling on deep-sea ecosystems and highlight the need for sustainable fisheries management strategies. Full article

Feeding habits of the four-spotted megrim, Lepidorhombus boscii, from the eastern Adriatic Sea were examined. A total of 1070 individuals collected using a bottom trawl net between July 2020 and June 2021 were analyzed. A high percentage of empty stomachs (63.27%) was recorded. The food composition proved that L. boscii is a carnivorous species. The identified prey of L. boscii was divided into seven groups: Teleostei, Bivalvia, Gastropoda, Cephalopoda, Isopoda, Mysida, and Decapoda. Decapods were the most important prey (%IRI = 58.18), followed by cephalopods (%IRI = 10.93). At the species level, the most important prey were the decapods Parapeneus longirostris (%IRI = 11.48) and Goneplax rhomboides (%IRI = 5.92). Statistically significant seasonal variations in diet were recorded; decapods dominated in spring, summer, and winter, whereas cephalopods prevailed in autumn. There were no statistically significant differences in the food composition between the three size categories. Decapods were the most important prey in all size categories (%IRI > 50). The lowest feeding intensity, as well as the highest percentage of empty stomachs, was recorded in winter, which is also the main spawning season of this species in the Adriatic Sea. Full article

The use of environmental DNA (eDNA) metabarcoding to analyze fish species diversity across different aquatic ecosystems is well documented. Nonetheless, there is a gap in validating eDNA metabarcoding studies on the diversity and structure of fish communities in coastal ecosystems, particularly in comparing these findings with bottom trawl catch data. In this study, we employed eDNA metabarcoding to explore species composition and relative abundance in fish communities, taxonomic-level diversity variations, and the interplay between community structures and environmental factors in the Yellow Sea and compared these results with those obtained from bottom trawl catches. In addition, we compared the various methods used to estimate the distributions of taxonomic, phylogenetic, and functional diversity factors. We found that eDNA metabarcoding detected a greater number of species (86 vs. 41), genera (73 vs. 37), and families (42 vs. 25) than bottom trawl results at each sampling station. eDNA metabarcoding provided higher Shannon, Simpson, and Chao1 alpha diversity indices than the bottom trawl results. The PCoA results showed that eDNA metabarcoding samples could be more clearly separated at the sampling sites in the Zhuanghe (ZH) and Lianyungang (LYG) areas than bottom trawling samples. The RDA analysis indicated that temperature, along with NO3- and NH₄⁺ concentrations, were pivotal in shaping the geographical patterns of fish communities, as identified through eDNA metabarcoding, echoing findings from bottom trawling studies. Furthermore, our findings suggest that eDNA barcoding surpasses bottom trawling in detecting taxonomic and phylogenetic diversity, as well as in uncovering greater functional diversity at the local level. Conclusively, eDNA metabarcoding emerges as a valuable complement to bottom trawling, offering a multifaceted approach to biodiversity monitoring that not only boosts efficiency but also reduces environmental impact on coastal ecosystems. Full article

The abundance of the Russian sturgeon population in the Sea of Azov declined many times in the XX–XXI centuries. This paper presents long-term annual and spatial occurrence datasets to create statistical and machine learning models to better understand the distribution patterns as well as biological and ecological features. The annual dataset provides annually averaged results of environmental and biotic population estimates obtained by in situ observations for 1925–2024. The spatial occurrence dataset contains raw survey observations with a bottom trawl over the period of 2000–2024. Preliminary diagnostics of the annual dataset reveal no evidence of non-stationarity or significant outliers that cannot be explained by biological parameters. The published dataset allows any researcher to perform statistical and machine learning-based analysis in order to compare and describe the population abundance or spatial occurrence of Russian sturgeon in the Sea of Azov. Full article