Search Results (34)

Small pelagic fish, including sardines, are essential to global fisheries and aquaculture feed production. However, these species are increasingly exposed to intense exploitation. In Chile, the common sardine (Strangomera bentincki), endemic to the Humboldt Current System, supports major industrial and artisanal fisheries. Landings are expected to reach 300,000 tons by 2025, mostly for fishmeal production. As a keystone species, S. bentincki is highly sensitive to environmental variability during early development, which can reduce recruitment and threaten long-term population sustainability. This interdisciplinary approach integrates ecological and biotechnological perspectives to assess the feasibility of controlled juvenile sardine production in land-based Ecological Aquaculture (EA) systems, including Recirculating Aquaculture Systems (RAS) and Integrated Multi-Trophic Aquaculture (IMTA), which are designed to reduce environmental impacts. These systems enable precise control of temperature, feeding regimes, and water quality, facilitating investigations into larval and juvenile survival, growth performance, and physiological responses under variable thermal and nutritional conditions. Emphasis is placed on fatty acid metabolism during ontogeny, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are essential for somatic growth, reproductive development, and thermal tolerance. Developing standardized protocols for juvenile S. bentincki culture addresses key gaps in husbandry and physiology (temperature threshold, nutrient density, larval growth rate, etc.) while introducing a novel ecological–aquaculture integration framework. This approach links early-life ecology with applied rearing techniques to support stock enhancement, strengthen artisanal fisheries, and promote sustainable aquaculture diversification under increasing environmental variability. Full article

The Japanese chub mackerel (Scomber japonicus) is a small pelagic economically important fish species in the northwest Pacific Ocean, and its abundance and distribution are influenced by water temperature changes. In recent years, frequent marine heatwaves (MHWs), defined as prolonged anomalously warm sea surface temperature events, in this region have significantly impacted marine ecosystems and fishery resources. The effects of MHWs on Japanese chub mackerel remain poorly understood. This study analyzed the relationship between Japanese chub mackerel abundance and MHW characteristics in the northwest Pacific Ocean from 2014 to 2021. It includes comparative analyses on the spatiotemporal patterns of catch per unit effort (CPUE) and MHWs, an exploration of CPUE distribution under varying MHW intensities and durations, and an assessment of the relationship between MHW characteristics and CPUE using a Generalized Additive Model (GAM) approach. Additionally, CPUE variations before, during, and after MHWs in 2016, 2018, and 2021 across different regions are measured. Results reveal significant interannual variability in MHWs, with increasing trends in the frequency, intensity, and duration of MHWs. As the frequency, intensity, and duration of MHWs increased, the abundance of Japanese chub mackerel decreased, particularly in years with higher intensity and longer lasting MHWs. The study concludes that MHWs negatively impact Japanese chub mackerel, highlighting the urgent need for climate-adaptive fishing and management strategies. Full article

Marine heatwaves (MHWs) have become increasingly frequent and intense, raising concerns about their impacts on fisheries production and economic value. We present a global assessment of MHW-related impacts across 2088 marine fisheries from 1985 to 2022. Using high-resolution satellite data and standardized catch production and catch value, we identified significant reductions in catch and ex-vessel value during years of elevated thermal stress. A total of 322 fisheries (15%) showed statistically significant declines during years with high MHW activity, with regional disparities indicating that the Northeast Atlantic and Southeast Pacific experienced the highest cumulative losses, while country ranking highlighted Norway, China, Japan, and Peru as the most affected. Estimated accumulated global losses since 1985 exceeded 5.6 million tonnes and USD 6.6 billion (2005 USD equivalents), nearly 40% of which occurred during 2013–2022. These findings emphasize the need to incorporate extreme thermal events into fisheries risk assessments and adaptation strategies, especially in highly productive or strategic regions. Full article

Fish stocks and their management are paramount for sustainable fisheries under the ongoing changes in atmosphere–sea interactions. The Aegean Sea, one of the composite seas influenced by different water masses, is characterized by a diverse ecosystem. Small pelagic fish are abundant and tend to form schools that vary in size. One of the most efficient and rapid techniques for sampling fish schools over a large area is the use of acoustic methods. Therefore, an acoustic survey was conducted in the coastal areas along the entire Turkish Aegean waters between June and August 2024, using a scientific quantitative echosounder equipped with a split-beam transducer operating at 206 kHz. During the survey, environmental parameters, including water physics, optics, and bathymetry, were measured at 321 stations. Additionally, satellite data were used to obtain water primary production levels for each sampling month across the entire study area. Using a custom computer algorithm written during the present study in MATLAB (2021a), fish schools were automatically detected to measure various morphological and acoustic features. Through a series of statistical analyses, three optimal clusters, validated with the total silhouette sum of distances (1317.38), were identified, each characterized by specific morphological, acoustic, and environmental variables associated with different areas of the study. School morphology and acoustic properties also varied with bottom depth. Cluster 1 was mostly found in open and relatively deep waters. Cluster 2 appeared in areas impacted by anthropogenic sources. Principal Component Analysis (PCA) revealed that the first component (PCA1) was correlated with school height from the bottom (HFB) and overall school height (SH), followed by minimum depth (MnD), maximum depth (MxD), and volume backscattering strength at the school edge (SvE). The second component (PCA2) was associated with school width (SW) and area (A). Cluster 1 was characterized by schools with large SW and A, and relatively high HFB and SH. Cluster 2 showed low HFB and SH, while Cluster 3 had high MnD and MxD and low SvE. Based on the descriptors for these clusters, each cluster could be attributed to fish species at different life stages inferred based on target strength (TS), namely sardine, horse mackerel, and chub mackerel, distributed along the entire Turkish Aegean coast. Full article

Chub mackerel (Scomber japonicus) is a typical small pelagic fish in the high seas of the Northwest Pacific Ocean (NPO), with great ecological and economic values. It is crucial to understand the spatio-temporal distribution and the population dynamics of chub mackerel for commercial fishing and fishery management. In this study, we analyzed the population dynamics and stock status of chub mackerel based on commercial fishing data. Results showed that from 2016 to 2021, high catches of chub mackerel were concentrated along the outer edge of Japan or Russia’s exclusive economic zone line, and the gravity center of the fishing grounds moved to the northwest gradually, with a decrease in the average value of catch per unit effort (CPUE) year by year. The fishing pressure may not be the major reason for the decrease in chub mackerel as the resource biomass was at a high level. The body length structure was reasonable, and large individuals were still present. The study highlights the fact that the population status of chub mackerel was healthy in 2016–2021 according to our results. However, it has to be emphasized that resource exploitation and fishery management also need to take into account the influence of climatic conditions. Full article

Cold-water lakes in high-latitude regions are experiencing rapid changes in community structure and functioning associated with local and global stressors (e.g., climate change, hydropower and invasive species). However, the long-term ecological responses of cold-adapted top predators are relatively poorly monitored despite their high importance for structuring ecological communities and for the provisioning of ecosystem services. We studied long-term changes (2010–2021) in the population structure and trophic niche of two cold-adapted coregonid fishes in oligotrophic Lake Osensjøen, southeastern Norway. Our gillnet surveys indicated that the whitefish (Coregonus lavaretus) population declines simultaneously with the increasing population density of roach (Rutilus rutilus), whereas vendace (Coregonus albula) showed more stable densities. Both whitefish and vendace became increasingly dominated by small-sized individuals following the increase in coexisting roach and perch (Perca fluviatilis) populations. Our stomach content and stable isotope data indicated a marked overlap in the trophic niches of whitefish and roach, with both species showing high among-individual variation in δ¹³C and δ¹⁵N values as compared to the more specialized zooplanktivorous vendace. Our study provides further evidence that the ongoing environmental changes in high-latitude lakes may induce rapid changes in community structures and lead to the population declines of cold-adapted fishes, likely associated with strong resource competition with warm-adapted cyprinid and percid fishes. Such shifts in fish community structure may, in turn, affect the benthic and pelagic food-web compartments and reduce valuable ecosystem services such as local fisheries targeting salmonids. Full article

The study explores the interactions between dolphins and Cypriot fisheries, emphasizing the economic impact and fisher perceptions through data collected from structured interviews with small-scale and large pelagic fishers. The research documents frequent dolphin interactions, impacting catch and gear in both fishing sectors. Reported financial losses and gear damage highlight a significant economic burden, with annual losses averaging EUR 6144 for small-scale and EUR 29,882 for large pelagic fishers. Efforts to mitigate these interactions, such as using acoustic deterrents, have shown mixed results, reflecting dolphins’ adaptability to human activity. While some fishers use deterrents, others remain hesitant due to cost and inconsistent efficacy. The study underscores the need for improved, sustainable solutions that integrate fisher input to enhance acceptance and effectiveness. Findings suggest that dolphins are increasingly relying on fishing activities as a foraging strategy, aligning with broader trends in the Mediterranean. In the context of EU Directive 2014/89/EU, the study integrates ecological considerations and socioeconomic impacts to ensure balanced marine management strategies. This work emphasizes the complexity of human–wildlife conflicts in marine environments, suggesting that further research and collaboration with fishers are essential to developing adaptive strategies that balance conservation with the economic needs of local fishing communities. Full article

Understanding the dynamic spatial distribution and characteristics of fishing activities is crucial for fisheries management and sustainable development. In recent years, small pelagic fish and cephalopods in the Arabian Sea have become new targets for light purse seine fishing; however, there is a lack of publicly available reports. This study uses automatic identification system (AIS) data from January to May and October to December of 2021 to 2022 in the region between 58°–70° E and 10°–22° N to extract spatial distribution information through three methods. The results show that with a spatial resolution of 0.25° × 0.25°, the spatial similarity index between the fishing ground information extracted in 2022 and catch data was consistently above 0.60, reaching 0.76 in March 2021 and 0.79 in November 2022, while the spatial similarity index in March 2022 exceeded 0.71. The spatial distribution of fishing effort and kernel density was similar to that of the fishing grounds, and the fishing intensity information exhibited the highest spatiotemporal similarity with commercial catch data, making it more suitable as a substitute for fishery data. Therefore, effective international cooperation and efficient joint management mechanisms for fishing vessels are needed to enhance the regulatory oversight of fishing vessels in this region. Integrating AIS data with other technological methods is crucial for more effective monitoring and management of fishing vessels. The findings presented in this paper provide both quantitative and qualitative scientific support for resource conservation and sustainable development in the region. Full article

Small pelagic fishes play important ecological roles in marine ecosystems, constitute some of the most economically valuable fisheries resources, and play a vital role in West African food security. Often living in upwelling regions, these species appear to have developed mechanisms to cope with environmental variability, such as opportunistic reproductive tactics, enhancing their growth performance, or increasing their egg production by following the more predictable system attributes of seasonal cycles. To test this hypothesis, we investigated size-dependent patterns of the two growth mechanisms (i.e., growth rate) of two West African small pelagic populations (Ethmalosa fimbriata and Sardinella maderensis) in upwelling environments. These results were discussed with other areas in African tropical Atlantic waters. The monthly mean length of both species showed a large variation over the study period. Based on the fish length-frequency data and a coastal upwelling index, we found that the growth peaks of the species tended to occur during the most intense periods of upwelling (March–April). This study showed a significant decrease in size compared with other species found in other regions. It demonstrates how the geographical distribution of the same species, together with location-specific variation in temperature and food, can combine to determine local and regional growth responses in pelagic fish. Changes in growth rate may be an adaptive tactic in response to environmental change, as well as phenotypic plasticity in fish. This knowledge is essential to predict future changes in fish productivity and distribution vs. climate and to provide effective advice for ecosystem-based management. Full article

In Mexico, marine acoustics research still faces technical and scientific challenges. For the past decade, the country has made a sustained effort to implement acoustic techniques to generate time series of standardized information; however, these data have been underutilized. Marine acoustics research has been used mainly for small pelagic species and has contributed to improving fishery management and to advising stakeholders. The Mexican scientific community has perceived marine acoustic techniques as expensive tools that are only used for industrial fishing purposes. Marine acoustics can provide information on the variability and interactions between species, their physical environment, and other communities of species, but this approach has not yet been integrated into interdisciplinary research programs or ecosystem models. Additionally, acoustic data provide estimates of biomass and indices of relative abundance, and they have suitable statistical properties for use in integrated catch-at-age models. In summary, to consolidate marine acoustic techniques in Mexico, it is necessary, at a minimum, to maintain the current infrastructure for acoustic studies, to increase the budget for the development of monitoring programs that collect ecosystem indicator data, to promote the training of human resources, and to encourage peer review of the information generated and reported in gray literature. Full article

In the context of ecosystem-based fisheries management (EBFM), multi-species models offer a potential alternative to traditional single-species models for managing key species, particularly in mixed-fishery settings. These models account for interactions between different species, providing a more holistic approach to fisheries compared to traditional single-species management. There is currently no comprehensive list or recent analysis of the diverse methods used to account for species interactions in fisheries worldwide. We conducted a systematic review to objectively present the current multi-species models used in fisheries. The systematic search identified 86 multi-species models, which were then evaluated to assess their similarities. Employing a clustering analysis, three distinct groups were identified: extensions of single-species/dynamic multi-species models, aggregated ecosystem models, and end-to-end/coupled and hybrid models. The first group was among the most diverse, owing to their ability to integrate biological components, while maintaining an intermediate level of complexity. The second group, primarily defined by the EwE method, features an aggregated biomass pool structure incorporating biological components and environmental effects. The third cluster featured the most complex models, which included a comprehensive representation of size and age structure, the ability to incorporate biological components and environmental effects, as well as spatial representation. The application of these methods is primarily concentrated on small pelagic and demersal species from North America and Europe. This analysis provides a comprehensive guide for stakeholders on the development and use of multi-species models, considering data constraints and regional contexts. Full article

Despite the sector’s minor contribution (0.5%) to the Gross National Product, the fisheries sector in Cyprus is particularly important to the micro economy of coastal communities, offering direct and indirect employment and supporting small family businesses. Like any industry, the Cypriot fisheries sector faces its own challenges and opportunities. The current study aimed to identify the strengths, weaknesses, opportunities, and threats (SWOT) of the fisheries sector in Cyprus based on fishers’ knowledge and to provide strategic recommendations based on the sector’s identified needs. Following a participatory approach, a workshop with 30 small-scale fishers, six large pelagic longline fishers, and three scientists was conducted in November 2023. Fishers and scientists worked together to conduct the SWOT and the TOWS matrix (a reverse SWOT) analyses. Findings from the SWOT–TOWS analyses were used to develop strategic recommendations for the sector. Finally, using the Impact–Effort prioritisation method, the strategic recommendations were prioritised according to their potential impact on the sector and the effort required for their implementation. Based on the analyses, the study proposes 12 strategic recommendations that could significantly improve the sector’s overall performance and sustainability, which if applied will give a light of hope for the future of the Cypriot fisheries sector. Full article

Japanese anchovy (Engraulis japonicus) is a small pelagic fish with commercial and ecological importance. In spite of its importance, in recent years, specific research on anchovy in the Shandong Peninsula area has been relatively scarce and outdated. This study aims to estimate the age and growth characteristics of anchovy through year-round seasonal sampling from 2016 to 2017, utilizing length–frequency and otolith microstructure analysis. The higher coastal abundance and larger size observed in the spring and summer suggest a potential peak spawning period for anchovies dominated by larger-sized individuals. Based on otolith analysis, anchovies range in age from 0 to 4 years, with a limited presence at age 0 and dominance in the age-1 group. The length–weight relationship (LWR) equation shows hyper-allometric growth for each season, with a mean relative condition factor (K_n) of 1.025 ± 0.005, indicating good health. Additionally, the von Bertalanffy growth equation of can be expressed as L_t = 154.40 [1 − e^{−0.604 (t + 0.965)}], suggesting a medium growth rate (K = 0.604). These findings contribute to the understanding of anchovy age and growth patterns, emphasizing the continuous need for research and monitoring to support rational and sustainable fisheries management and conservation efforts. Full article

Long-term variations in population structure, growth, mortality, exploitation rate, and recruitment pattern of two major commercial small pelagic fishes (CSPFs) (Decapterus maruadsi and Trachurus japonicus) are reported based on bottom trawl survey data collected during 2006–2020 in the Beibu Gulf, South China Sea. All individuals collected during each sampling quarter over a period of 15 years were subjected to laboratory-based analysis. In this study, the stock of D. maruadsi and T. japonicus inhabiting the Beibu Gulf was assessed using length-based methods (bootstrapped electronic length frequency analysis (ELEFAN)) to complete stock assessment in different fishery management periods (the division of fisheries management periods was based on China’s input and output in the South China Sea offshore fisheries over 15 years, specifically divided into period I (2006–2010), period II (2011–2015), and period III (2016–2020)). The results showed that the mean body length, dominant body size, and estimated asymptotic length of two CSPFs decreased, whereas their growth coefficient decreased, indicating miniaturization and slower growth, respectively. Estimated exploitation rates and catching body length for two CSPFs indicated that both stocks in the Beibu Gulf were overexploited in period I and moderately exploited after 2011. These stocks were taking a good turn in status in period III, with the exploitation rate much lower than the initial period and reversing the downward trend in catching body length. Furthermore, the variations in the spawning season of the two CSPF stocks and their barely satisfactory expected yield indicated the complexity of the current fishery management in the Beibu Gulf. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of those CSPFs in the Beibu Gulf; however, the stock structure already affected by overfishing will be a huge challenge for the conservation and restoration of fisheries resources in the future. Given that the current stocks of D. maruadsi and T. japonicus in the Beibu Gulf still have low first-capture body length (L_c) and high fishing mortality (F) (compared to F_0.1), we identify a need to refine population structure by controlling fishing efforts and increasing catchable size, and more consideration should be given to the local fishery resource status in fisheries management. Full article

The northeastern waters of Guishan Island constitute one of the crucial fishing grounds for coastal trawl fishery in Taiwan and have been exploited for many decades. To construct the marine ecosystem and to examine the interactions among trophic levels of fisheries resources in the waters of Guishan Island, historical catch, catch composition, biological information, fishing effort, environmental data such as sea surface temperature, salinity, and nutrients were analyzed using Ecopath with Ecosim. The results indicated that the longline and drift net fisheries have a very minor incidental catch of cetaceans, with a fishing mortality (F) of 0.01 year⁻¹ and an exploitation rate (E) of 0.03. The F and E were 0.308 year⁻¹ and 0.617 for small skates and rays, and were 0.261 year⁻¹ and 0.580, respectively, for small sharks. The F and E of the dolphinfish, Coryphaena hippurus, an important pelagic species, were 0.411 year⁻¹ and 0.245, respectively. Fisheries had negative impact on major commercial species except the dolphinfish and the oil fish, Lepidocybium spp., which benefited from the reduction of their predators or competitors. The keystone species of the Guishan Island marine ecosystem is phytoplankton, which has the lowest trophic level and great biomass, and is an important energy source of the ecosystem. The influences of zooplankton and anchovy rank as second and third, respectively, with regard to the keystone species in the ecosystem due to their great biomass. Regarding the biomass of less abundant species, carangids had the highest influence followed by hairtail due to their feeding habits. The results of simulations using Ecosim indicated that the hairtail, small sharks, skates and rays, mackerels, and marine eels will benefit if fishing efforts are reduced by 30%. On the other hand, the biomass of phytoplankton, zooplankton, demersal benthivores, and shrimps will decrease due to the increase in the biomass of their predators. Full article