Reviews in Fish Biology and Fisheries最新文献

The Chinese sturgeon (Acipenser sinensis) is a critically endangered, large migratory fish that serves as a vital indicator of ecological status of marine and river environments. Conservation efforts for Chinese sturgeon primarily focus on freshwater rearing, potentially leading to smaller adult sizes and higher disease incidence due to limited exposure to marine environments. Thus, it is imperative to study the behavioural characteristics and marine life history of artificially reared populations in seawater environments. In this study, acoustic telemetry technology was employed to investigate the behaviour of the Chinese sturgeon. We deployed an acoustic array at a nearshore-fenced marine farm on Bailong Island and conducted a one-year (December 2020–December 2021) tracking of ten acoustic-tagged fish, comprising five adults and five juveniles. We generated distribution heat maps and analysed displacement during typhoons and tidal events to differentiate activity levels. Annual distribution revealed areas of distinct increased density, with adults displaying a denser distribution compared to the more scattered pattern observed in juveniles. Rhythmic behaviour in response to tidal cycles was observed. During typhoon periods, individuals exhibited reduced activity levels but increased concentration, with no significant diurnal behavioral variations. These age-specific and environmentally responsive habitat preferences provide valuable supplementary insights into the species' life history and potential conservation strategies.

Graphical Abstract

Rachycentron canadum (cobia) is a marine fish species important to fisheries and aquaculture worldwide. The species has gathered scientific attention in the last decades, and today, a considerable body of knowledge exists on it. There are several reviews pertaining to different aspects of research, but a quantitative outlook has been lacking to identify contributors and motives for research on cobia. This study aims to present the first global research performance analysis on R. canadum through scientometrics. We found a total of 446 documents, published in the timespan of 1964–2023, from a variety of countries and sources. Although various countries have published studies on the species, a few countries concentrate the vast majority of research efforts. The most cited articles and the sources with most publications were mainly aquaculture-related. Some countries with high contribution to capture have a significant portion of their scientific production directed to aquaculture-related sources, while others have low scientific production in general. Some countries where the cobia fishery is present have had no research found at all. The boom in publication rate from the 2000s onwards exhibits a similar tendency to the rate of aquaculture production over the years, with aquaculture probably representing the main research driver for R. canadum. We recommend focusing additional scientific endeavors on wild cobia populations in countries where its fishery holds significance. Furthermore, we suggest that the currently existing aquaculture focus on the species may overshadow research interest on its fisheries.

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Tag-recapture programs to monitor the movements of fish populations are among some of the longest-running citizen-science datasets to date. Here, using half a century of yellowtail kingfish (Seriola lalandi, Carangidae) tag-recapture data collected through citizen-science projects, we report novel insights into population connectivity in Australia and New Zealand (NZ). Despite the importance of kingfish in commercial and recreational fisheries, substantial knowledge gaps about their stock structure and connectivity between jurisdictions hinder current management efforts. Between 1974 and 2022, 63,432 releases and 4636 recaptures (7.3%) of tagged kingfish were collected in Australia and NZ. Most tagged individuals (51.4%) were recaptured within 10 km of their original release location up to 14 years post-release (mean: 225 days), indicating some degree of site fidelity. However, 656 (14.2%) kingfish were recaptured over 100 km from their release location, with one fish travelling at least 2834 km in 702 days. Seasonal variability was evident for releases and recaptures, with more releases occurring in summer and autumn in most jurisdictions. Network analysis of recaptures revealed no connectivity between tagged kingfish from western and eastern Australia, supporting genetic delineation. By contrast, extensive connectivity exists across eastern Australia and NZ, with 87 kingfish moving between five Australian state jurisdictions, 316 individuals travelling across 15 bioregions and six kingfish moving between Australia and NZ. Our findings provide important new insights into the structure and connectivity of the eastern Australia kingfish stock and suggest increased collaboration between state and international fisheries jurisdictions may support improved stock assessment and management.

In the Mediterranean Sea, pelagic longline fisheries, targeting tuna and swordfish, have contributed significantly to the bycatch of threatened chondrichthyan species, such as blue shark (Prionace glauca). The Mediterranean blue shark population is assessed as critically endangered, making a timely implementation of mitigation measures crucial. A comprehensive understanding of blue shark habitat use dynamics is essential for deriving appropriate mitigation measures. This study aimed at evaluating vertical movement behaviour and investigating factors potentially influencing the movements of blue sharks in the Mediterranean Sea. Twenty-six blue sharks, bycaught in a longline fishery in the southern Adriatic, were tagged with pop-up satellite archival tags. Analysis of data from thirteen recovered tags revealed a distinctive diel movement pattern. Blue sharks used shallower waters during the night and deeper waters during the day, characterised by steep ascents and descents during sunset and sunrise, respectively. In addition, lunar phases were also influencing the depth of blue shark movements, with sharks using deeper waters right before and during full-moon. Shark size, salinity, currents, spatial location and time of the year were additional factors influencing blue shark depth use. The observed tendency of blue sharks to use deeper areas at daytime and prior and during the full moon period offers possibilities to develop and test bycatch mitigation strategies. Aligning longline fishing schedules and fishing depths with blue shark behaviour during the fishing seasons could hold promise to effectively reduce spatio-temporal overlap between fishing and blue shark distribution and may ultimately decrease the bycatch impact of the fishery.

Besides providing key ecosystem services, including improved water quality, coastal protection, and carbon sequestration, seagrasses are highly productive habitat-forming species essential in supporting fish diversity at the global level. In the Mediterranean Sea, seagrasses represent the main component of the sublittoral marine environment hosting a huge number of fish species that use this habitat for reproduction, foraging and/or refuge from predation. However, a complete synthesis of fish species observed in different seagrass habitats is still lacking at the whole Mediterranean basin scale, so hindering a thorough understanding of the main mechanisms involved in determining fish diversity patterns. We performed a systematic review by implementing a semi-automated, threshold-based filtering pipeline that allowed building up a dataset concerning all fish species reported in native Mediterranean seagrasses, including specific functional traits known to be involved with the potential use of seagrasses by fish. These data allowed to carry on a narrative synthesis on fish diversity in seagrass habitats, providing support to several assumptions repeatedly stated in literature but so far sustained mainly by local and fragmented data. Our findings suggested the onset of a general pattern in the occurrence of species, mostly based on life history and driven by body size and feeding habits. We evidenced unexpected knowledge gaps on the role of habitat heterogeneity and fish life stages in determining the presence and the potential use of seagrasses by species. In depth studies are therefore needed to better understand the mechanisms behind the structuring of fish communities, fundamental for the maintenance of marine biodiversity.

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The settlement phase is a challenging period for meropelagic octopus, as they adapt to their new life in the sea bottom after a planktonic period. Their ecology and trophic interactions with the surrounding fauna in the wild are practically unknown. To understand their predatory role in the littoral zone, the diet of recently settled Octopus vulgaris from a Mediterranean sandy bottom was studied through molecular methods. Amphipods were present in all the analysed stomach contents, with a total of 20 amphipod taxa recorded as prey. Jassa slatteryi and Microprotopus maculatus were the most commonly found amphipod species. Hydrozoans, decapod crustaceans, cephalopods and bivalves followed amphipods in importance. Niche breadth index assigned to small recently settled octopus the role of a specialised predator, increasing the diversity of prey as they grow. Larger juveniles displayed a higher number of prey taxa suggesting a decreasing predatory specialisation with octopus size and an ontogenetic shift in trophic ecology from diet mainly based on amphipods to a richer diet. The considerable arm elongation and the strong muscular arm crown development after settlement probably allow the juvenile benthic octopus to develop ambush predation and speculative hunting, increasing the range of potential benthic prey species along its adaptation to the benthos.

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The understanding of the role of fishes in the trophic functioning of estuaries has increased in stages over many decades. It began with qualitative and quantitative dietary studies, mainly from the 1970s onwards, and progressed to more sophisticated stable isotope work towards the end of the 20th Century and into the present. Building on an initial wide array of predominantly single species rather than community dietary studies, our global knowledge of the food and feeding ecology of fishes in estuaries has now progressed to a stage where we can begin to discern patterns and make generalised statements on the nature and role of fish assemblages in the trophic functioning of these systems. In this review we summarize the dominant aspects relating to the trophic ecology of fishes in estuaries, including ontogenetic changes in fish diet and food provision for the nursery function of estuaries, detritus as a direct and indirect driver of the food web, the influence of latitude and habitat type on trophic structuring, predator prey relationships with an emphasis on the importance of invertebrates in fish food chains, the role of stable isotopes in combination with dietary analyses in understanding trophic functioning, and the effects of environmental change and fishing and other human activities on fish food webs in estuaries. Apart from providing an overview of information on the current status of our knowledge on fish trophic ecology in estuaries, this review also identifies important research gaps that need to be filled.

Plastic pollution represents a global environmental issue. Awareness of plastic pollution in marine organisms increased strongly during the last decades, including chondrichthyans. Due to a lack of a broad and comprehensive view of this global issue in chondrichthyans, we synthesized the 48 publications covering 54 species since 2002, and employed bibliometric analysis and data exploration to summarize the historical progression of the development, characteristics of plastics in chondrichthyans and evaluate their potential impacts across various regions, habitats, and Red List categories. The bibliometric analysis revealed that the investigation of plastic distribution in demersal sharks inhabiting the nearshore areas of the Mediterranean and northeastern Atlantic Ocean is a major research focus. Based on the current evaluation, plastics have been ubiquitously discovered within sharks, skates, and rays; however, only less than 5% of chondrichthyans worldwide have been investigated. Among these, 25 species are classified under one of the three threatened categories (critically endangered, endangered or vulnerable), according to IUCN Red List. The average abundance (all specimens) and load (specimens that contained plastics) in chondrichthyans were 2.86 ± 7.71 items/individual and 4.91 ± 9.39 items/individual, respectively. Plastic abundance/load is not influenced by the sampling regions, habitats, or Red List categories; however, higher records were found in the endangered and near threatened species. The plastics are predominantly fibrous in shape, with blue and black being the predominant colors, along with polypropylene and polyethylene in polymer type. Notably, inconsistencies in sampling, processing, and identification methods across studies might impeded the integration and comparison of data. This review highlights the potential implications of plastic pollution from chondrichthyans on biodiversity conservation and emphasizes the necessity to consider intra- and inter-specific variations in biometric and ecological characteristics, as well as establish standardized protocols to facilitate effective comparisons in contamination dynamics between studies of chondrichthyans.

Marine biodiversity monitoring in the Mediterranean’s increasingly threatened ecosystems is crucial for effective ecosystem conservation and management. Here, we leveraged the Mediterranean International Trawl Survey program (MEDITS) to implement eDNA sampling through the recently tested ‘metaprobe’ procedure and characterize fish assemblages in three separate areas off the Italian coasts: Northern Adriatic Sea (NoAS), Ligurian and Northern Tyrrhenian Sea (LNTS), and Sardinian Sea (SaS). By combining the information from two homologous mitochondrial 12S metabarcodes––i.e., Elas02 and Tele02 targeting elasmobranchs and teleosts, respectively––we identified 108 species, over 60% of which overlapped with those caught by the trawl net. We produced an accurate reconstruction of fish community composition of the examined sites, reflecting differences in species assemblages linked with both geographic area and depth range. Metaprobe eDNA data consistently returned a biodiversity ‘bonus’ mostly consisting of pelagic taxa not captured through bottom trawl surveys, including rare and endangered taxa (e.g., elasmobranchs). Overall, the spatial characterisation of the assemblages across the surveyed areas was better delineated and more robust using eDNA metabarcoding than trawl data. Our results support the operationalisation of the metaprobe as a simple, inexpensive, versatile sampling tool, in association with pre-existing ship surveys, to overcome many of the limitations of marine data collection and strengthen marine management.

The Xisha Islands constitute the largest coral reef archipelago on the northern margin of the Coral Triangle and are the largest coral reef archipelago among the islands in the South China Sea. This study employed various survey methods including underwater spearfishing, gill netting, handline fishing, longlining fishing, underwater visual surveys, and environmental DNA (eDNA). Additionally, historical data from 1956 to 2023 were reviewed to comprehensively analyze the adaptation characteristics of the fish community structure in the Xisha Islands. The Xisha Islands have documented a total of 874 coral reef fish species, categorized into 27 orders, 102 families, and 337 genera. Of these species, the order Perciformes demonstrated the greatest species richness, which represents 71.05% of the total fish species documented. The structure of coral reef fish communities in the Xisha Islands has undergone significant changes. Firstly, a significant decline in the population of large-sized and carnivorous fish species was observed. The proportion of large-sized fish species diminished by 6.02% (62 species), and the medium-sized fish species saw a reduction of 3.09% (51 species). In contrast, there was a surge of 9.12% in the small-sized fish species population. The carnivorous fish species experienced a decrease of 4.73% (102 species), while an increase was noted in the population of herbivorous and omnivorous fish species. Secondly, the numbers of orders, families, and genera have also significantly decreased, with noticeable declines in the average taxonomic distinctness (Delta +), the variation taxonomic distinctness (Lambda +), functional richness (FRic), and quadratic entropy (RaoQ). Thirdly, the similarity between fish species at different time periods is relatively low. Among different functional groups, large-sized and carnivorous fish species exhibit the lowest similarity, whereas herbivorous fish species exhibit the highest. The turnover of live coral fish species is also evident. Overall, the coral reef fish in the Xisha Islands are showing a trend towards herbivory, miniaturization, and a simplification in species composition and functionality. This study contributes to a better understanding and prediction of the adaptation trends in fish species composition in the Xisha Islands, which is crucial for ensuring the ecosystem services of coral reefs and for the conservation and restoration of ecosystems.