Reviews in Fish Biology and Fisheries最新文献

Over one third of sharks, rays and chimaeras (chondrichthyans) are threatened with extinction globally. In the Mediterranean Sea, more than half of chondrichthyan species face this risk, although a variety of international, regional, and national rules and regulations apply directly and indirectly targeting management and conservation for these species. In this work, we provide an overview of relevant legislation and policies in the region, which regulate, inter alia, commercial fisheries, while highlighting through cases studies how implementation in practice at national level looks like. Horizontal gaps and inconsistencies that hinder chondrichthyan management in the region are also illustrated. Furthermore, we present recommendations for improvement and additional tools that can be used, even if not originally or explicitly targeting chondrichthyans, for improving the management of these taxa in the Mediterranean.

The white shark (Carcharodon carcharias) is a globally distributed top predator. Due to its ecological importance and historical declining population trends, data contributing to conservation initiatives (e.g. habitat protections and resource management) pertaining to all life stages of this species are essential to facilitate population recovery. Of particular interest, the locations and discrete seasonality of C. carcharias parturition remain uncertain. Understanding C. carcharias parturition in relation to each population is relevant to population recovery since neonate to young-of-the-year (YOY) sharks are more vulnerable to predation and particularly threatened by and susceptible to commercial fishing pressure. Herein, this paper provides a synthesis from published literature across seven well-studied C. carcharias populations to identify common trends associated with parturition location, seasonality, and habitat characteristics. The data reviewed in this study are consistent with previous population-specific hypotheses, that C. carcharias parturition occurs during spring and summer for all populations. Further, this review also indicates that parturition likely occurs in insular shelf waters and water temperatures ranging from15.7 to 23.1 °C. Although discrete parturition sites were not identified, the compiled data are suggestive that C. carcharias parturition may occur over horizontal and vertical spatial scales that exceed the inshore, shallow water environments associated with nursery area habitat to perhaps minimize predation by conspecifics. Due to the vulnerability of C. carcharias, conducting non-lethal technological (e.g., baited remote underwater video systems—BRUVS), morphological (i.e., ontogenetic changes in dorsal fin shape), and reproductive (e.g., blood chemistry and ultrasonography) research that may help identify parturition location and seasonality are thus warranted.

Sea urchin roe is a high-quality product in terms of its nutritional value, valuable biochemical composition, and acquired taste. Urchin stocks, however, have been overfished worldwide and new candidates for commercial harvesting and aquaculture are required to satisfy the demand from the expanding market. The green sea urchin Strongylocentrotus droebachiensis from Russian waters of the Barents Sea may be considered a new source for potential consumers. We summarized available information regarding distribution patterns, feeding, reproduction, and growth as well as studies focused on farming of this species to assess the fishery and aquaculture potential of the area. This species is abundant in the coastal zone where it is commonly associated with laminarian kelp. The brown algae Saccharina latissima is the primary diet for S. droebachiensis but it also consumes animal foods. Red king crabs are the main predators for sea urchins but they do not significantly affect the S. droebachiensis population. A spawning peak of S. droebachiensis is registered in March–April. Green sea urchins reach a commercial size of 50 mm diameter at age 6 and the estimated stock of commercial urchins is 50,000–81,000 t. The most promising sites for harvesting are Varanger-fjord and Bolshoy Oleniy Island plus Porchnikha Bay. The best harvesting seasons are February–March and September–October. Sea-based rearing systems appear to be the most suitable approach for sea urchin aquaculture based on grow-out of adult animals fed on algal or mixed diets.

Evaluation of fish stock status is a key step for fisheries management. Tuna Regional Fisheries Management Organizations (t-RFMOs) are moving towards management strategy evaluation (MSE), a process that combines science and policy and depends on technical aspects, developed by scientists, designed to meet management objectives established by managers and other stakeholders. In the Indian Ocean, the current management advice for swordfish (Xiphias gladius) is based on an ensemble of 24 models considering four areas of uncertainty about the stock dynamics. There is an ongoing MSE process for swordfish, and this paper describes the methodology being applied for the conditioning of the operating model (OM), including model selection and validation. In the MSE, nine sources of uncertainty were considered, each being characterized by 2–3 levels. A partial factorial design was employed to reduce the number of models from a full factorial design to those needed to encompass the overall uncertainty. A selection and validation process was carried out, filtering models that converged, showed good predictive skills, and provided plausible estimates. Overall, the estimated spawning stock biomass (SSB) relative to SSB at maximum sustainable yield (MSY), and fishing mortality (F) relative to F_MSY encompasses the estimates of the stock assessment ensemble at the most optimist area of the distribution. The MSE for swordfish is an ongoing process that is expected to provide more robust management advice in the future. Further developments to the OM can still occur, but the methods presented herein can be applied to this, or other species, MSE processes.

Between 2009 and 2021 almost the complete beam trawl fleet of the Netherlands switched from conventional beam trawls (BT) to pulse trawls (PT) using electrical stimulation to catch sole, Solea solea. Electric fishing, being banned in the EU in 1988, was made possible in 2006 under a derogation. Over the years stakeholders expressed concern about ecosystem effects. Here we review the research conducted. PT improved the selectivity of the fishery and reduced the ecological side effects. PT caught more sole per hour fishing but less discards and benthos than BT. The transition to PT reduced the surface area swept (lower towing speed), sediment depth of disturbance and associated benthic impacts, as well as fuel consumption. Laboratory experiments with 9 fish and 17 benthic invertebrate species showed that exposure to a commercial bipolar pulse stimulus did not result in harmful effects except in cod. Autopsy of cod sampled from PT revealed that 40% had an internal injury. Injury rates in other roundfish species was low (< 2%) and absent in flatfish. Electrical-induced impacts on biogeochemistry were not observed. The transition increased competition with other fishers which fed the resentment against PT. Governance arrangements under which the number of temporary licenses expanded, undermined legitimacy of the gear, resulting in a ban in 2021. Although questions about the ecological impact of electrical stimulation remain, adverse effects are considered negligible in comparison with the benefits.

The Rab family of proteins is involved in organelle regulation, trafficking, signal transduction, mitosis, phagocytosis, growth differentiation, cytoskeleton protein depolymerization and other cellular functions and abnormal expression has been associated with many pathologies, including cancer. Previous work has focused on Rab function in higher animals but fish, crustaceans and other aquatic animals also express the Rab proteins. The current review summarizes research progress on Rab proteins, focusing on immune defense against pathogens in aquatic animals. Some differences in Rab protein function between aquatic and higher animals were found and greater involvement in the fish and crustacean immune system than that of higher animals. Novel insights into Rab protein in aquatic animals are offered with implications for the development of aquaculture strategies.

Overfishing and unsustainable practices have caused drastic declines in shark populations worldwide; these decreases are largely attributed to the demand for shark products (e.g., fins and meat) and shark bycatch associated with the global fishing industry. In an effort to understand the species composition of the shark fin trade in Singapore – a globally significant trade hub, we collected and genetically identify a total of 6840 shark fins collected between January 2021 and February 2022. We then adopted a Bayesian modelling approach to understand how the identified species contributed to the overall trade within Singapore. The Singapore market appears distinct in terms of species composition when compared to the markets of Hong Kong and mainland China. In Singapore 81% of samples belonged to ten species, whereas, in Hong Kong and mainland China a single species dominated the trade. Of those identified in Singapore, the IUCN considers six to be threatened species and eight are listed in CITES Appendix II (in online). The differences in species composition between East and Southeast Asian markets suggest that different supply chains are sustaining these hubs. Given these differences, it is important that conservation, sustainable fisheries management and policy decisions are based upon the findings from multiple trade centres.

Some hosts harbor more parasites than others. Overdispersion of parasitism suggests that coevolution with parasites may be more important to the biology and ecology of certain species. We examined patterns of parasitism and host traits in fished decapod crustaceans, which are economically and ecologically important worldwide. Using a synthesis approach, we determine that host life history, including habitat, longevity, sociality, invasion history, and fisheries involvement, correlate with the number and type of parasite species harbored. Indicator species analysis revealed close relationships between decapods and certain parasite groups, including crabs with rhizocephalans and dinoflagellates; crayfish with mesomycetozoans, oomycetes, branchiobdellids, and fungi; lobsters with copepods and amoebae; and shrimp with viruses. In contrast, Nematomorpha and Nemertea appear to be under-represented and under-studied as parasite groups in decapods. Decapods that are commercially fished, aquacultured, introduced outside their native range, and/or exhibit parental care tend to have higher parasite species richness (PSR). Parasite richness also increases with how well-studied a host group is, which we addressed with a machine learning algorithm that predicts false negative associations. Geographic range is commonly positively correlated with parasite richness, however reliable ranges are not available for most decapod species, highlighting a significant future research need. Identifying patterns such as these increases our broad understanding of decapod disease ecology but also enabled us to develop a series of recommendations on how to focus future research, management, and aquaculture development efforts.

Climate change is impacting marine species, leading to shifts in their distribution to higher latitudes and to deeper locations. Parasite communities are dynamic systems influenced by biotic and abiotic factors, making them valuable tools for studying ecological processes of their hosts. This work aims to assess possible changes in parasite structure that occurred in the northern stock of Cynoscion guatucupa in the Argentine Sea, over approximately 25 years, by using parasites as tags in a region characterized as a hotspot of significant warming in recent decades. Parasite assemblages of adult and juvenile fish from two periods caught at two regions of the Argentine Sea were analyzed. Species richness remained relatively constant across samples, although four of the eight compared species from juvenile fish showed significant increases in prevalence, while for adults three species decreased. Differences in parasite assemblages were significant between periods, but not between regions, indicating that the stock structure has apparently remained stable in recent years, even under a warming process that, in turn, seems to have affected its parasite assemblages which however, continue showing homogeneous parasitological attributes throughout the habitats. Most results indicate that changes in parasite burdens are not related to the population density or geographic distribution of C. guatucupa, but to changes in temperature, salinity or in the density of top predators. Parasites seem to have felt the impact of global change before their host, thus, they can be considered early sentinels to monitor the stability and distribution of this important resource.

The Amazon basin, spanning approximately 540,000 km², exhibits distinct fluviometric surfaces that differentiate between the dry and rainy seasons. This seasonality, along with hydrological connectivity and the creation of new habitats during the rainy season, significantly promotes the migration, reproduction, and feeding of potamodromous fishes. To estimate the realized niches of species, species distribution models (SDMs) employ the extrapolation of environmental predictors and species occurrence data. Our objective was to compare the spatial distribution of migratory fish species in the Amazon basin using SDMs based on variables characterizing the dry season, rainy season, and a combination of both. All evaluated treatments demonstrated high performance and exhibited different distribution ranges in the applied SDMs, particularly when combining environmental variables with occurrence data during the rainy season. These findings support the hypothesis that spatial distribution is influenced by seasonality. The increased fluviometric surface and enhanced connectivity of the rainy season favor both longitudinal and lateral migrations of Amazonian migratory catfishes. Moreover, the spatial distribution reveals four critical spatial overlap (CSO) regions with higher population densities regardless of the season. These CSOs primarily coincide with the Amazon alluvial plain, which exhibits the highest rates of endemism, species richness, and abundance of organisms. Considering the discontinuous and heterogeneous nature of fluviometry when performing niche modeling processes is pivotal, although SDMs applied in the Amazon generally ignore such regional seasonality.