Search Results (967)

Broadband backscattering measurements of Pacific mackerel (Scomber japonicus) can improve acoustic surveys of the species for the management of its fisheries throughout the Pacific Ocean. The determination of its target strength (TS), the logarithmic form of the backscattering cross-section, is the aim of this work. It was measured for fourteen individual specimens, eight in a freshwater tank and six in a seawater tank, using calibrated broadband echosounders spanning the frequency band 24–84 kHz. The TS is expressed as a function of frequency and tilt angle, with fish length as a parameter. The individual broadband TS patterns with the tilt angle of fish showed size and frequency dependencies. The fish length-normalized TS of mackerel decreased with increasing fish length-to-acoustic wavelength ratio (l/λ) in the small l/λ range (approximately 2–6) but was flat in the larger l/λ range (>6). This variation in the normalized TS indicates that a pair of regression equations is necessary to span the range of commercially important mackerel relative to the acoustic wavelength. The relative l/λ characteristic of the normalized TS showed constant values with tilt-angle distributions over a large l/λ range and can be used as a characteristic of acoustic backscattering for discrimination among species. Full article

Phyllodoce koreana was first described in 1985 in Gwangyang Bay, a semi-enclosed bay in Korea affected by significant organic input from the Seomjin River and dredging activities near the Gwangyang Port. Since then, this Korean endemic species has received limited attention in taxonomic and ecological studies. Phyllodoce koreana is known for its resilience to mild disturbances but is vulnerable to severe environmental changes. In this study, P. koreana specimens were collected from organically polluted Asian stalked tunicate aquaculture farms at eight sites in Jindong Bay, a location with environmental conditions similar to those of Gwangyang Bay, over the course of five sampling events from March to November. Both bays experience benthic hypoxia in summer due to elevated water temperatures and organic matter accumulation. Phyllodocid specimens were primarily collected in March and November 2023, non-hypoxic periods, suggesting potential seasonal adaptations to environmental fluctuations. The morphological features of the collected specimens were consistent with the original description of P. koreana, confirming their identification. Additionally, we reported previously overlooked morphological details, contributing to a more comprehensive taxonomic understanding of the species. We also present, for the first time, the complete mitochondrial genome of this species, comprising 15,559 bp, which provides essential genetic data for future taxonomic and phylogenetic studies. The phylogenetic analysis of protein-coding genes shows that, among 17 related polychaete species, P. koreana (family Phyllodocidae) is closely related to the family Goniadidae. Future research should expand our knowledge of polychaete taxonomy by integrating additional mitochondrial genomes and investigating the role of conserved gene synteny within Polychaeta. Full article

The purpleback flying squid (Sthenoteuthis oualaniensis) is an economically significant cephalopod species in the Northwest Indian Ocean. Predicting its fishing grounds can provide a crucial foundation for fishery management and production. In this research, we collected data from China’s light-purse seine fishery in the Northwest Indian Ocean from 2016 to 2020 to train and validate the AlexNet and VGG11 models. We designed a data partitioning method (DPM) to divide the training set into three scenarios, namely DPM-S1, DPM-S2, and DPM-S3. Firstly, DPM-S1 was employed to select the base model (BM). Subsequently, the optimal BM was lightweighted to obtain the optimal model (OM). The OM, known as the AlexNetMini model, has a model size that is one-third of that of the BM-AlexNet model. Our results also showed the following: (1) the F1-scores for AlexNet and AlexNetMini across the datasets DPM-S1, -S2, and -S3 were 0.6957, 0.7505, and 0.7430 for AlexNet and 0.6992, 0.7495, and 0.7486 for AlexNetMini, suggesting that both models exhibited comparable predictive performance; (2) the optimal dropout values for the AlexNetMini model were 0 and 0.2, and the optimal training set proportion was 0.8; (3) AlexNetMini utilized both DPM-S2 and DPM-S3, yielding comparable outcomes. However, given that the training duration for DPM-S3 was relatively shorter, DPM-S3 was selected as the preferred method for data partitioning. The findings of our study indicated that the lightweight model for the purpleback flying squid fishing ground prediction, specifically AlexNetMini, demonstrated superior performance compared to the original AlexNet model, particularly in terms of efficiency. Our study on the lightweight method for deep learning models provided a reference for enhancing the usability of deep learning in fisheries. Full article

The abundance, spatial distribution of and dynamic changes in ichthyoplankton species affect the recruitment and fish population dynamics, which are fundamental for stock assessment and fisheries management. An evaluation of alternative sampling designs needs to be carried out to determine the optimal scheme that is cost-effective in collecting high-quality ichthyoplankton data. A simulation study was conducted to evaluate the performances and consistency of six potential sampling designs for an ichthyoplankton survey in the coastal waters of the central and southern Yellow Sea. Relative estimation error (REE) and relative bias (RB) were used to measure the performances in estimating the population abundances of five target ichthyoplankton species in different sampling designs. In general, the two systematic sampling (SYS) designs had high precision and accuracy estimation and remained stable over years for estimating the population abundance of ichthyoplankton species compared with the other four sampling designs. SYS did not result in the overestimation or underestimation of the mean population abundance. Most sampling designs showed relatively high accuracy in abundance estimation when sample sizes were higher than medium levels. This study could improve the performances of sampling designs of ichthyoplankton surveys and provide a reference for the further optimization of sampling designs. Full article

Aquatic foods play a pivotal role in transforming food systems. As the world’s leading producer, consumer, and trader of aquatic products, China’s potential for sustainable supply and consumption is critical to understand. The aim of this study was to depict the dynamic trends of aquatic products and the consequences of sustainable diets and environmental impacts. A panel dataset about Chinese aquatic products covering the period from 1952 to 2023 was drawn for analysis. Diet sustainability was assessed with the deviation from the Dietary Guidelines for Chinese Residents (2022) and EAT-Lancet recommendations. The environmental impacts of aquatic products’ supply and consumption were assessed using carbon footprints and water footprints. The findings reveal that aquatic products’ supply increased from 4.65 million tons to 71.16 million tons from 1978 to 2023, and annual aquatic food consumption per capita increased from 3.50 kg in 1978 to 15.20 kg. While overall supply meets consumption needs, structural imbalances persist at the provincial level. Over time, the influence of marine fishery products has declined from 1.06 million tons (63.63%) in 1952 to 35.85 million tons (50.38%) in 2023, whereas offshore aquaculture shows promising potential for meeting future supply demands (23.96 million tons in 2023, accounting for 66.82% of marine fishery production). To align with healthy dietary goals and environmentally sustainable food systems, provincial aquatic food demand across China was adjusted. The carbon footprints and water footprints of both current and adjusted consumption patterns were also assessed. The results indicate that adjusting consumption based on the Dietary Guidelines for Chinese Residents (2022) and EAT-Lancet recommendations could reduce environmental impacts to different degrees. The findings could offer valuable references and insights into developing sustainable strategies in aquatic product management and advancing food system transformation. Full article

The coastal waters of Zhejiang feature a complex aquatic environment and abundant biological resources, creating an ideal habitat for various fish species. However, the systematic monitoring of fish larvae in these offshore waters is limited. This study collected 24,232 fish larvae using large plankton nets during April and November 2022, as well as February and July 2023, and identified 93 species, primarily warm-temperate and warm-water species, with a peak occurrence in summer. The dominant species include Larimichthys croceus, Sebastiscus marmoratus, Lateolabrax japonicus, and Odontamblyopus lacepedii, among others, and these species exhibit frequent seasonal changes. Fish larvae are typically found to be aggregated along estuaries and bays in spring, autumn, and summer, while in winter, they tend to shift towards areas near the boundaries of motor trawler fisheries areas. Our cluster analysis revealed spatial heterogeneity in the community structure, driven by an abundance of dominant and important species. Our Mantel tests and canonical correspondence analysis (CCA) identified seawater temperature and salinity as core drivers of the aggregation and distribution of fish larvae, interacting with factors such as the chlorophyll-a concentration, water turbidity, water depth, and dissolved oxygen. This research provides a scientific basis for the dynamic monitoring of spawning grounds and effective management of fishery resources in Zhejiang’s coastal waters. Full article

Impact assessments are necessary for supporting fisheries’ disaster applications and management options for states affected by disasters. This paper measures the joint and individual impacts of man-made and natural disasters, global pandemics and recessions, the U.S.-China trade war, and recent increases in fuel prices on commercial dockside values of the Mississippi blue crab fishery. The mean-difference model estimates the direct impacts when the current dockside values fall below the benchmark values. The marine economic recovery model identifies the significant determinants of the variations in the dockside values. Mean-difference model results indicate that the Mississippi blue crab fishery sustained direct losses due to Hurricane Katrina in 2005, the Deepwater Horizon oil spill in 2010, and the opening of the Bonnet Carre Spillway in 2011. The estimated marine economic recovery model explained 93 percent of the variations in real dockside values. Two independent variables are statistically significant, including blue crab landings and time. The disaster variables have the expected signs but are not statistically significant. These methodologies’ usefulness is applicable in assessing the direct impacts on fisheries and other economic sectors affected by disasters such as major hurricanes, oil spills, massive freshwater intrusion, and harmful algal blooms. Full article

This study estimated the economic value of international fisheries observer programs for Korean distant water fisheries using the contingent valuation method (CVM). The model included economic factors, socio-demographic variables, and proxy variables that reflected participants’ familiarity with seafood consumption. An online survey was conducted with 16,924 participants, of whom 1000 provided usable responses (resulting in a final response rate of 5.9%). The survey results indicated that 74.2% of households were willing to pay to support international fisheries observer programs. The weighted average willingness to pay (WTP), adjusted for the participation rate, was estimated at USD 7.01 per household, leading to an annual aggregated WTP of USD 153,097,825. These findings highlight the significance of international fisheries observer programs in promoting the sustainability and effective management of Korean distant water fisheries. Full article

Spawning grounds may shift due to climate change and subsequent variations in the marine environment, but few studies have aimed to project shifts in the spawning grounds of chub mackerel driven by climate change. We projected the effects of climate change on the spawning grounds of chub mackerel (Scomber japonicus) by developing and applying a suitable spawning ground index based on a regional ocean circulation model for the western North Pacific. Our model indicated that the potential spawning grounds of chub mackerel extended from southern waters of the East China Sea to the Korea Strait, Yellow Sea, and Japan/East Sea. Despite some uncertainty, our model based on climate change scenarios projected that, by the 2050s, spawning grounds will shift northward due to warming of the ocean surface, resulting in a subsequent westward shift of nursery grounds from the Japan/East Sea to the Korea Strait and Yellow Sea. Our projections will contribute to clarifying the impacts of climate change on the distribution of exploitable chub mackerel, the adaptation of fisheries to climate change, and the reliability of stock assessments used for fisheries management in the region. Full article

To evaluate and compare the effectiveness of prediction models for Argentine squid Illex argentinus trawling grounds in the Southwest Atlantic high seas based on vessel position and fishing log data, this study used AIS datasets and fishing log datasets from fishing seasons spanning 2019–2024 (December to June each year). Using a spatial resolution of 0.1° × 0.1° and a monthly temporal resolution, we constructed two datasets—one based on vessel positions and the other on fishing logs. Fishing ground levels were defined according to the density of fishing locations, and combined with oceanographic data (sea surface temperature, 50 m water temperature, sea surface salinity, sea surface height, and mixed layer depth). A CNN-Attention deep learning model was applied to each dataset to develop Illex argentinus trawling ground prediction models. Model accuracy was then compared and potential causes for differences were analyzed. Results showed that the vessel position-based model had a higher accuracy (Accuracy = 0.813) and lower loss rate (Loss = 0.407) than the fishing log-based model (Accuracy = 0.727, Loss = 0.513). The vessel-based model achieved a prediction accuracy of 0.763 on the 2024 test set, while the fishing log-based model reached an accuracy of 0.712, slightly lower than the former, indicating the high accuracy and unique advantages of the vessel position-based model in predicting fishing grounds. Using CPUE from fishing logs as a reference, we found that the vessel position-based model performed well from January to April, whereas the CPUE-based model consistently maintained good accuracy across all months. The 2024 fishing season predictions indicated the formation of primary fishing grounds as early as January 2023, initially near the 46° S line of the Argentine Exclusive Economic Zone, with grounds shifting southeastward from March onward and reaching around 42° S by May and June. This study confirms the reliability of vessel position data in identifying fishing ground information and levels, with higher accuracy in some months compared to the fishing log-based model, thereby reducing the data lag associated with fishing logs, which are typically available a year later. Additionally, national-level fishing log data are often confidential, limiting the ability to fully consider fishing activities across the entire fishing ground region, a limitation effectively addressed by AIS vessel position data. While vessel data reflects daily catch volumes across vessels without distinguishing CPUE by species, log data provide a detailed daily CPUE breakdown by species (e.g., Illex argentinus). This distinction resulted in lower accuracy for vessel-based predictions in December 2023 and May–June 2024, suggesting the need to incorporate fishing log data for more precise assessments of fishing ground levels or resource abundance during those months. Given the near-real-time nature of vessel position data, fishing ground dynamics can be monitored in near real time. The successful development of vessel position-based prediction models aids enterprises in reducing fuel and time costs associated with indiscriminate squid searches, enhancing trawling efficiency. Additionally, such models support quota management in global fisheries by optimizing resource use, reducing fishing time, and consequently lowering carbon emissions and environmental impact, while promoting marine environmental protection in the Southwest Atlantic high seas. Full article

The European sardine (Sardina pilchardus) ranks among the most valuable species of Iberian fisheries, and the accurate tracing of its geographic origin, once landed, is paramount to securing sustainable management of fishing stocks and discouraging fraudulent practices of illegal, unreported, and unregulated (IUU) fishing. The present study investigated the potential use of S. pilchardus white muscle fatty acids (FAs) to successfully discriminate the geographic origin of samples obtained in seven commercially important fishing harbors along the Iberian Atlantic Coast. While 35 FAs were identified using gas chromatography–mass spectrometry in the white muscle of S. pilchardus, the following, as determined by the Boruta algorithm, were key for sample discrimination: 14:0, 22:6n-3, 22:5n-3, 18:0, 20:5n-3, 16:1n-7, 16:0, and 18:1n-7 (in increasing order of relevance). An average 83% correct allocation of landed specimens was achieved, with some landing locations presenting 100% correct allocation (e.g., Ría de Pontevedra in northern Spain and Peniche in central Portugal). Linear discriminant analysis revealed a separation of samples from northern Spain and Peniche, and a partial overlap of all other locations. The present results highlight the potential of using FAs of S. pilchardus white muscle to reliably discriminate the geographic origin of landed individuals along the Iberian Atlantic coast. Full article

Spotted Seatrout Cynoscion nebulosus (hereafter, trout) are one of the most heavily targeted sportfish along the Gulf coast. With recent regulation changes intended to reduce the harvest mortality of trout and promote a healthy trophy-class trout fishery in Texas, understanding differences between trophy-class (>28 in, 712 mm) and adult-class (12–28 in, 305–710) trout has become especially relevant for fisheries managers. Here, we leveraged a long-term (1983–2023) gill net dataset collected by the Texas Parks and Wildlife Department to (1) compare the distribution of size classes both spatially and temporally, (2) determine environmental drivers of the abundance of each size class, and (3) compare the species associated with each size class in the Upper Laguna Madre. Kernel density distribution estimates, hot spot analyses, and space–time pattern mining methods were used to compare the distribution of the two size classes of trout spatially and temporally. Boosted regression trees (BRTs) were used to determine the environmental drivers of abundance, and multivariate analyses were utilized to compare the species associated with each size class. Trophy-class trout exhibited a greater degree of spatial clustering than adult-class trout, with abundance peaks concentrated along specific shorelines in Baffin Bay. Significant changes in trophy-class trout distribution over time were also found, indicating that the spatial clustering of trophy-class trout has intensified over the past four decades. Salinity and bay were strong predictors for the abundance of both size classes, with peak abundances of both trophy-class and adult-class trout in Baffin Bay and its tertiary bays and at salinities of 10–30 and above 60 psu. Dissolved oxygen (DO) concentration and temperature were good predictors of the abundance of trophy-class trout, which were most abundant at temperatures of 25–30 °C and DO levels of 5–8 mg/L. Depth, turbidity, and season were good predictors of the abundance of adult-class trout, which were most abundant at increased depths (>2 m), low-to-moderate turbidity (~125 NTU), and in the spring season (April–June). Multivariate analyses revealed differences in the communities associated with trophy-class and adult-class trout occurrence, with species such as Black Drum Pogonias cromis, Striped Mullet Mugil cephalus, and Ladyfish Elops saurus more abundant in samples associated with trophy-class trout. These results indicate that trophy-class trout display unique spatial patterns and species associations and that their abundance may be driven by a distinct set of hydrological and biotic factors, which may have important implications for the management of trophy fisheries. Full article

Managing fishery resources is crucial to ensure the marine environment continues to provide diverse goods and services. To overcome difficulties of classical methods used for fish stock management, molecular tools have shown potential to address this issue assessing both targeted and non-targeted species. This study aims to evaluate the spatiotemporal diversity of fish using 12S rRNA gene eDNA metabarcoding sequencing in the Berlengas archipelago and compare two seawater eDNA sampling sources: samples collected by fishermen during their activities and those collected by our research team. The results indicated that autumn presented the highest diversity and that the area around Berlenga Island was the richest area, increasing biodiversity across the region. Fisher-collected samples were generally less diverse than those by the research team but detected species typical of deeper and open-ocean habitats, validating this sampling method. Our study also highlighted eDNA’s role in monitoring fish species by detecting unexpected species for the region, such as Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua), while cautioning against false positives like orange clownfish (Amphiprion percula) and blue tilapia (Oreochromis aureus). Future optimisation of our eDNA sampling methodology could better refine marine ecosystem dynamics around the UNESCO Biosphere Reserve of the Berlengas Archipelago, Portugal. Full article

Off-seasonal water level regulations disrupt the biological traits and phenological rhythms of native fish species, yet their impacts on interspecific trophic interactions remain understudied. This study employed stable isotope analysis to assess the trophic dynamics of three fish species (Parabramis pekinensis, Carassius auratus, and Toxabramis swinhonis) across different water periods in Hongze Lake. The findings revealed that all three species occupied similar mid-level trophic positions, with no significant difference among water periods (p > 0.05). During high-water periods, P. pekinensis and T. swinhonis exploited broader niches, while C. auratus relied on a narrower diet. In contrast, during low-water periods, C. auratus expanded its niche, while P. pekinensis and T. swinhonis reduced their isotopic niche widths. Niche overlap analysis showed minimal trophic overlap among the three species during high-water periods, with increased overlap during low-water periods, except for the highest overlap between C. auratus and T. swinhonis during mid-water periods. This variation in niche overlap aligns with shifts in dietary reliance, as POM was the predominant dietary component for all three species, but its contribution varied significantly across different water periods. These findings indicated that adaptive trophic niche facilitated the coexistence of these fish species, while off-seasonal water level regulation may intensify interspecific competition. These insights are essential for refining water management policies and developing sustainable fishery management strategies of Hongze Lake and other water-level-regulated systems. Full article

Under growing recognition of the need to restore marine ecosystems and promote the sustainable use of ocean resources, this research delves into an analysis of studies on artificial reefs in the marine environment spanning from 1996 to 2024 to explore how they have evolved in supporting biodiversity growth and fishery management while also promoting ecosystem sustainability over time. Using tools like CiteSpace 6.3. R1 and VOSviewer 1.6.18, a total of 586 research publications were examined to pinpoint authors, current trends in research, and emerging focal points. This study highlights the roles played by countries such as the United States, China, and Australia, as well as esteemed institutions, like NOAA and the Chinese Academy of Fisheries Sciences leading the field. In this field of study, there are topics like restoring the environment to its natural state and making fisheries more sustainable by creating habitats with diverse structures and elements; this shows how artificial reef research involves different areas of expertise working together for a common goal. The findings suggest a trend towards using tools such as ecofriendly materials and 3D printing to improve the design and ecological functionality of reefs. However, some challenges still exist, such as conducting assessments on the long-term effects on the environment and finding a balance between promoting biodiversity and meeting the needs of people in terms of economic aspects. This research highlights the importance of countries working together and adapting their strategies to ensure that artificial reefs play a role in protecting marine life and using ocean resources in a sustainable way. By charting out the existing knowledge landscape, this study lays the groundwork for research endeavors focused on tackling these obstacles and propelling the field forward. Full article