Search Results (31)

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

Illegal, unreported, and unregulated (IUU) fishing significantly threatens marine ecosystems, disrupts the ecological balance of the oceans, and poses serious challenges to global fisheries management. This contribution presents the efficacy of China’s summer fishing moratorium using BeiDou vessel monitoring system (VMS) data from 2805 fishing vessels in the East China Sea and Yellow Sea, integrated with a deep learning framework for spatiotemporal analysis. A preprocessing protocol addressing multidimensional noise in raw VMS datasets was developed, incorporating velocity normalization and gap filling to ensure data reliability. The CNN-BiLSTM hybrid model emerged as optimal for fishing behavior classification, achieving 89.98% accuracy and an 87.72% F1 score through synergistic spatiotemporal feature extraction. Spatial analysis revealed significant policy-driven reductions in fishing intensity during the moratorium (May–August), with hotspot areas suppressed to sporadic coastal distributions. However, concentrated vessel activity in Zhejiang’s nearshore waters suggested potential illegal fishing. Post-moratorium, fishing hotspots expanded explosively, peaking in October and clustering in Yushan, Zhoushan, and Yangtze River estuary fishing grounds. Quarterly patterns identified autumn–winter 2021 as peak fishing seasons, with hotspots covering >80% of East China Sea grounds. The framework enables real-time fishing state detection and adaptive spatial management via dynamic closure policies. The findings underscore the need for strengthened surveillance during moratoriums and post-ban catch regulation to mitigate overfishing risks. Full article

Metapenaeus monoceros is the second most abundant commercially important shrimp species caught along the Saudi Arabian Red Sea coast. However, knowledge of its life history and population dynamics in the region remains limited, posing challenges for sustainable management. This study assessed the growth, maturity, and mortality of M. monoceros based on fishery-independent samples collected from shrimp trawling grounds off Al Qunfudhah and Jizan (October 2022–September 2023). Altogether, 10,859 specimens were examined, with a carapace length (CL) ranging from 7.98 to 49.10 mm and a total weight (W) in the range of 0.41 to 41.28 g. The observed sex ratio was 1.56:1 in favor of females. The CL–W relationship was W = 0.0024∙CL^2.58. The seasonalized von Bertalanffy growth parameters were CL_∞ = 50.66 mm, K = 0.35 year⁻¹, t_anchor = 0.43 years, C = 0.64, and t_s = 0.61 years for females, and CL_∞ = 38.97 mm, K = 0.55 year⁻¹, t_anchor = 0.51 years, C = 0.84, and t_s = 0.39 years for males. Females reached their first sexual maturity at 21.12 mm CL. The exploitation rates (0.60 for both sexes) indicated overfishing. Spawning potential ratio analysis showed that the current fishing pressure reduces the spawning stock biomass to 23% of unexploited levels. A 50% reduction in fishing effort, extended seasonal closures, and selective gear modifications are recommended to rebuild the stock and ensure sustainability. Full article

Transboundary water pollution is a major global challenge as its movement and impacts remain unsurveyed. Monitoring pollution along international borders can reveal some of the pathways by which sewage and chemicals enter water bodies, and can hence advance the implementation of measures to prevent leakages and discharges into international waters. In this paper, we surveyed the impacts of sewage pollution and chemicals along the U.S.–Mexico international border, using Imperial Beach (California) as a main case study. Pollution was primarily attributed to the inflow of contaminated waters from the neighboring city of Tijuana (Mexico), where a malfunctioning wastewater treatment plant and a lack of sewage pipes being upgraded have caused direct leakage and toxic discharges into the Tijuana River. Reported effects from water pollution at the Tijuana River estuary in Imperial Beach include frequent beach closure, damages to coastal ecosystems, negative impacts on the fishery industry, and several effects on the health of beach users and surfers. Hence, the situation requires urgent measures oriented at coastal management at the mouth of the Tijuana River as well as the consistent monitoring and reporting of human health effects linked to beach uses. Full article

Management strategy evaluation using the Method Evaluation and Risk Assessment (MERA) platform was used to evaluate management procedures (MPs) for improving the management of the leopard coral grouper (Plectropomus leopardus) fishery in Saleh Bay, Indonesia. This grouper is a valuable species currently under high fishing pressure. It is targeted by small-scale fisheries using a wide range of fishing methods; hence, management recommendations are needed to ensure sustainability. A suite of MPs for data-limited conditions were evaluated for their ability to achieve limit and target biomass reference points (B/B_MSY = 0.5 and B/B_MSY = 1, respectively), while maintaining a target yield of at least 0.5 MSY. The simulation results suggest that the currently implemented harvest control rules (HCRs) in Saleh Bay (size limit and spatial closure) may not be effective in achieving the management objective to attain the target biomass reference point due to relatively low compliance with the size limit regulation (320 mm total length) and the very small proportion of existing MPA no-take areas (~2.2%). This study recommends that the fisheries management authority explores the feasibility of implementing the total allowable catch (TAC) and seasonal closure in addition to the existing fishing regulations for P. leopardus in Saleh Bay. Full article

As recreational fishers act relatively autonomously, management relies heavily on voluntary compliance. Therefore, understanding fishers’ views on management options can be beneficial. This study used a two-phase approach of face-to-face interviews and subsequent online questionnaires to evaluate recreational fishers’ salient views on issues affecting the Blue Swimmer Crab (Portunus armatus) and Black Bream (Acanthopagrus butcheri) fisheries in Western Australia as well as current and potential management arrangements, including stock enhancement. The strength and heterogeneity of views were also determined. Minimum size limits were mainly considered acceptable or very acceptable, with restricting recreational fishing and spatial closures the least supported management options for both species, in addition to maximum size limits for crabs. These views were not always consistent across fishing locations for each species and among types of crab fishers, indicating heterogeneity in views. Stocking was the most acceptable of the management measures not already utilised for crabs and among the most popular for bream fisheries. Recreational fishers of both species believed stock enhancement could have strong positive outcomes for the abundance of their target species and increase their subsequent catches. They also recognized that some negative outcomes, e.g., increased fishing pressure and environmental issues, might occur but considered them unlikely. Full article

Harmful and toxic algal blooms (HABs) are an increasing concern for marine social-ecological systems. These unpredictable events threaten human health and may affect the viability of economic activities such as shellfish fisheries due to harvesting bans. Monitoring and early warning systems are developed to support management decisions to mitigate and reduce impacts. Nevertheless, HAB alert systems currently only focus on the environmental dimensions to identify the risk of bloom occurrences. Other socioeconomic dimensions associated with HABs are generally not taken into account to support decision making. Integrating information on the economic risk of HABs and on adaptive strategies of impacted communities would provide essential insights for decision makers. This study presents an analysis of how the potential impacts of HAB-related restrictions on economic activities can be effectively assessed to support decision making. A vulnerability-based approach is developed and applied to the case study of the French scallop fishery in the eastern English Channel. The results showed clear differences in vulnerability patterns between the studied fishing fleets despite their similar exposure. This is associated with the heterogeneity in individual characteristics in terms of sensitivity level and adaptive strategies. This research highlights the important effect of social factors such as adaptation in the magnitude of HAB impacts and supports the relevance of the vulnerability approach in the assessment of socioeconomic impacts of such events. Combining environmental and socioeconomic factors through a composite index can bridge the existing gaps in addressing and mitigating HAB impacts. Full article

The lack of data on the age, growth, and reproduction of the Atlantic Goliath Grouper Epinephelus itajara off the coasts of Florida (USA) makes it difficult to estimate the extent of their population recovery following the 1990 fishery closure, as well as the potential effects of the recent (2023) opening of a fishery for juveniles. Goliath Grouper from the Atlantic coast of Florida were non-lethally sampled for size (total length, TL), age (via fin rays), and sex and reproductive stage (via gonad biopsies, milt/egg expression, gonopores) from May to October 2010–2016. Of 653 unique fish captured (not including 118 recaptures), 257 (39.4%) were females (122–228 cm TL; 5–20 years old), 264 (40.0%) were males (104–225 cm TL; 4–22 years old), 100 (15.3%) were unsexed (82–211 cm TL; 3–15 years old), and 32 (4.9%) were protogynous hermaphrodites (108–209 cm TL; 5–20 years old). Protogyny was conclusively determined in two fish recaptured and re-biopsied that had transitioned from female to male. However, an overlap in the age and size of males and females, a 1:1 sex ratio, and the presence of relatively small, young, mature males, in combination with an apparently low functional sex change rate, all indicated that the sexual pattern of Goliath Grouper was functionally gonochoristic with the potential for diandric protogyny. Females > 10 years old were larger-at-age than males, and Goliath Grouper from the Atlantic coast were larger-at-age than fish from the Gulf of Mexico. These differences in age, growth, and reproductive strategy—as well as the nascent fishery for juveniles—need to be monitored closely so that the current and future reproductive capacity of the population continues to ensure growth and sustainability. Full article

Reliable data on Atlantic Goliath Grouper abundance are prerequisite to informed management decisions, particularly as the State of Florida reopened a limited harvest on the species in 2023 after a 32-year moratorium. Limited data exist for this purpose and fisheries data have been unavailable for over three decades due to a fishery closure that began in 1990. The purpose of this study was to compare absolute abundance estimates of Goliath Grouper between two years using an efficient, cost-effective method developed by Koenig. An underwater tagging method was used to collect mark and resight data for use in a Peterson deterministic model. These data were collected at the same spawning aggregation sites off Jupiter, Florida near the time of the new moon in September 2013 and August 2022. We found that Goliath Grouper abundance had declined at all but one of six sites since 2013. Because data were not collected during the intervening years, interannual variability is unknown. However, given the highly age-structured spawning stock of adult Goliath Grouper on the spawning grounds, the lower abundances measured in 2022 may reflect a real decline in the population rather than just representing a weak year of adult recruitment to these spawning sites. Full article

Calanus finmarchicus is a keystone zooplankton species that is commercially harvested and is critical in sustaining many important fisheries in the North Atlantic. However, due to their patchy population distributions, they are notoriously difficult to map using traditional ship-based techniques. This study involves the use of a combined approach of standardized ocean colour imagery and radiative transfer modelling to identify reflectance anomalies potentially caused by surface swarms of C. finmarchicus in the northern Norwegian Sea. Here, we have standardized satellite eRGB imagery that depicts a distinct ‘red’ patch, which coincides with in situ measurements of high surface concentrations of C. finmarchicus. Anomaly mapping using a novel colour matching technique shows a high degree of anomaly within this patch compared to the surrounding waters, indicating the presence of something other than the standard bio-optical model constituents influencing the optics of the water column. Optical closure between modelled and satellite-derived reflectance signals is achieved (and the anomaly is significantly reduced) through the addition of C. finmarchicus absorption into the model. Estimations of the surface concentrations of C. finmarchicus suggest between 80,000 and 150,000 individuals m⁻³ within the extent of the identified red patch. Furthermore, analysis of the impact of C. finmarchicus absorption on the OC3M algorithm performance points to the potential for the algorithm to over-estimate chlorophyll concentrations if C. finmarchicus populations are present in the surface waters. Full article

This study provides the first socio-ecological overview of the Seriola dumerili fishery occurring in the Balearic Islands. This pelagic top-predator is among the five most valued fish resources of the Balearic community. Despite its ecological importance and potential vulnerability to aggregation fishing, few studies address the ecology of this large Carangidae species. Shining a light on its ecology is vital to ensure adequate species conservation and the sustainable and effective management of the fishery. Historical catches from 1950–1999, alongside detailed landing data for the last 21 years, were analysed to identify potential patterns in ecological and socio-economic factors. Significant inter-annual variability among the years was found in historical catches of greater amberjack, while catches and mean prices of the different size categories revealed significant results between seasons and months, respectively. Additionally, the purse seine fleet accounted for the highest percentage of S. dumerili catches. CPUE did not appear to change greatly between months and years after the annual 8-month fishing ban imposed in 2011 and therefore a re-evaluation of the closure was intended. Overall, this study suggests seasonality influences the S. dumerili fishery in the Balearic Islands, within which ecological influences show a higher regulating power than socio-economic factors. Full article

This paper reports the results of a 15-year trawl ban imposed in 1990 in the Gulf of Castellammare (GCAST: NW Sicily, central Mediterranean Sea) and its effects on the biomass and size structure of demersal finfish and shellfish and on the proportion of different commercial categories of fish. Data were collected by experimental trawl surveys conducted in the GCAST and in two trawled areas before and after 1990. The biomass of the total assemblage and of a number of selected species was significantly higher in the GCAST after the ban. Highly commercial species had the largest increase in the same gulf after the ban, particularly at the depths used by artisanal fishermen. The results from size-based indicators were not as clear-cut as those from biomass though. Although the length frequency distributions obtained in the GCAST were significantly different from the other gulfs, in several cases, the values of the size indicators were higher in the trawled gulfs. Our results suggest that, at the temporal and spatial scale adopted, trawl bans may drive full biomass recovery but only partial size structure recovery of the fish populations subject to trawl exclusion, at least in the Mediterranean. The trawl ban in the Gulf of Castellammare provides an example of an effective ecosystem-based fisheries management tool that offers the potential for fish stock rebuilding and for the economic sustainability of artisanal, small-scale fisheries. Full article

The Davao Gulf supports various livelihoods and activities for small-scale and commercial fisheries. However, facing a declining catch, a closed season was implemented to arrest the decline. This study aimed to describe the Davao Gulf fisheries, determine the movement patterns of fishing boats during closed and open seasons, and quantify and compare their catch and their fishing distances. Boat tracking was combined with catch logbook monitoring of fishers and supplemented with interview surveys (N = 35) and mapping surveys (N = 167), including the use of secondary catch data. Results from the interviews showed that the average age of the fishers was 45 years old, with 27 years of fishing experience using motorized boats with 8 HP engines. Their average catch was 7 kg per trip dominated by big-eyed scad (Selar crumenophthalmus), frigate tuna (Auxis thazard), roundscad (Decapterus spp.), skipjack tuna (Katsuwonus pelamis), and yellowfin tuna (Thunnus albacares). There were highly significant differences between the volume of catch of small-scale fishers and commercial fishers after the closure in 2014 (278 t vs. 80 t; p < 0.001) and between the species caught (p < 0.001). Fishing activities were associated with a speed class of 0–1 km/h, while the average moving speed was 5.28 km/h. Fishing ground overlap was common among fishers from the same port of origin but not fishers of different ports. Some fishers move farther away from their port during the closure period. Our study provided a better understanding of fishing effort distribution in the Davao Gulf. Full article

Small-scale fisheries (SSF) make a critical contribution in terms of employment and food security to coastal communities. Fish serves multiple purposes, mainly as a cheap source of protein and minerals for lower-income families. In order to help sustain this demand and to protect fishing resources, the closed season policy, temporal closure, and spatial closure were adopted to protect fish stocks and avoid fishery collapse. To assess the agreement and compliance of the three municipalities (Cortes, Lanuza, and Lianga) in Surigao del Sur to this policy, we surveyed their responses regarding this policy. We used focus group discussions, two focus groups per municipality (N = 80), followed by member checking to gather and clarify the data from six barangays with small-scale fishers (N = 192). The findings indicate that each community in the three municipalities studied have a different method of implementing the fishery closure or closed fishing season policy which resulted in a limited conservation impact on fish stocks. In the municipality of Cortes, 92% agreed with the policy, provided there would be enough money to comply with the policy. In Lanuza, 60% agreed to implement the policy, provided there would be alternative jobs available. In contrast, the municipality of Lianga, which did not implement this policy, had only 4% that agreed to impose the policy to restore depleted fish stocks. Other reasons for not implementing a closed season policy include lack of community organization, poor fishery management, and lack of strong government support for the policy. Moreover, fishers were only willing to stop fishing if they were given a subsidy of PHP 15,000 per month. In the long term, fishers who provide fish protein needs for the nation also need help and attention from policy and decision makers to realize sustainable fisheries. Full article

The impact of otter trawling on the relationship between functional traits of benthic invertebrates and specific biogeochemical processes were investigated in the oligotrophic Cretan Sea. The fishery is managed through a seasonal closure during the summer. During two seasons (winter and summer) replicate samples were taken from the field from a commercial trawl ground and an adjacent control area. Environmental parameters related to sediment biogeochemistry were measured including particulate organic carbon, sedimentary organic carbon, bottom water and sedimentary chlorophyll a and phaeopigment concentrations as well as benthic oxygen consumption. A significant impact of trawling was recorded only for bottom water chlorophyll and sedimentary organic carbon. Furthermore, the links between species traits and specific ecosystem processes were affected by trawling, highlighting the importance of unique functional modalities on ecosystem functioning. The traits that mostly influenced benthic biogeochemistry in the control sites were related to bioturbation and burrowing activities. In contrast, in the trawled sites, the associated traits were related to more opportunistic lifestyles and deposit feeding species that do not act as bioturbators. Thus, under trawling disturbance, this shift can decouple the species-sediment relations and affect nutrient cycling. Full article