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Aim: Mobulid rays are a group of threatened batoid fishes susceptible to population decline from targeted fisheries and accidental capture. Spatial distributions of mobulid rays remain poorly known. Prior studies found commonalities between favourable environments and prey among various mobulid species, yet most were conducted in tropical waters. To explore the habitat use and distribution of mobulid rays in a temperate environment we model the habitat suitability of two mobulid rays (Mobula mobular and Mobula birostris) in Aotearoa New Zealand using fisheries and citizen science occurrence data spanning almost two decades. Location: Northeastern coast of Aotearoa, New Zealand. Methods: Boosted Regression Tree models were used to predict the annual habitat suitability and favourable environmental conditions of the two species based on available sightings records in conjunction with high resolution (1 km2) environmental data. Results: The sympatric study species had contrasting habitat requirements. We found a separation in their spatial distribution defined by the 200 m isobath – the onshore extent for M. birostris and the offshore extent for M. mobular. While there were only subtle variations in relative habitat suitability for M. mobular over the study period, M. birostris exhibited greater interannual variability. Despite differing interannual patterns, spatial separation, as a function of environmental properties, persisted regardless of the year. Main Conclusions: Our results suggest that associations between mobulid species may differ from tropical regions due to regional adaptations to prey availability or local environmental conditions unique to colder and more productive temperate waters. Our findings highlight the importance of multi‐species surveys and the inclusion of temporal variability in support of separate species‐specific management plans to account for differing stressors impacting each species. [ABSTRACT FROM AUTHOR]

The growth of animal aquaculture requires ever more feed. Yet, fish and crustacean farming is argued to be sustainable because wild fish use is low and has improved over time. Here, accounting for trimmings and by-products from wild fish in aquaculture feed, and using four different sources of industry-reported feed composition data, we find ratios of fish inputs to farmed outputs of 0.36 to 1.15--27 to 307% higher than a previous estimate of 0.28. Furthermore, a metric that incorporates wild fish mortality during capture and excludes unfed systems raises the wild fish mortality-to-farmed fish output ratio to 0.57 to 1.78. We also evaluate terrestrial ingredients in aquaculture feeds. Widely cited estimates of declines in wild fish use from 1997 to 2017 entailed a trade-off of more than fivefold increase in feed crops over the same period. Our assessment challenges the sustainability of fed aquaculture and its role in food security. [ABSTRACT FROM AUTHOR]

Differences in the availability of prey may explain the low numbers of southern resident killer whales and the increase in northern resident killer whales in British Columbia and Washington State. However, in-situ data on the availability of their preferred prey (Chinook salmon, Oncorhynchus tshawytscha) in the core feeding areas used by these two populations of fish-eating killer whales have been lacking to test this hypothesis. We used multi-frequency echosounders (38, 70, 120, and 200 kHz) to estimate densities of adult Chinook (age-4+, > 81 cm) within 16 hot-spot feeding areas used by resident killer whales during summer 2020 in the Salish Sea and North Island Waters. We found Chinook were generally concentrated within 50 m from the bottom in the deep waters, and tended to be absent near the surface in the shallow waters (< 50 m). In general, the densities of Chinook we encountered were highest as the fish entered the Salish Sea (from Swiftsure Bank in the south) and Johnstone Strait (from Queen Charlotte Strait to the north)—and declined as fish migrated eastward along the shoreline of Vancouver Island. Median densities of Chinook for all sampled areas combined were 0.4 ind.·1000 m−2 in northern resident foraging areas, and 0.9 ind.·1000 m−2 in southern resident killer whale areas (p < 0.05, Mann–Whitney U test). Thus, Chinook salmon were twice as prevalent within the hot-spot feeding areas of southern versus northern resident killer whales. This implies that southern resident killer whales have greater access to Chinook salmon compared to northern residents during summer—and that any food shortage southern residents may be encountering is occurring at other times of year, or elsewhere in their range. [ABSTRACT FROM AUTHOR]

Vulnerability of elasmobranchs to fishing and declines in populations over the last decades have prompted calls for improved fisheries management and conservation efforts. The Raja clavata (Thornback ray) population in the Greater North Sea ecoregion is a population that has historically shown marked declines with increasing industrialized fishing, while a lack of robust catch data of commercial fisheries hampers assessment of population abundance. Using fisheries-independent survey catch data haul-by-haul surface area estimates, we employ integrated-nested Laplace approximation to estimate total and size-class abundances of R. clavata. By accounting for spatio-temporal changes in the population, size selectivity between survey gears, and minimizing bias from partially overlapping survey areas, we demonstrate major changes in the abundance and distribution over the past three decades. Notably, increases of abundance in the Eastern English Channel and south-eastern North Sea result in an overall increase in the abundance and biomass of the population. Our findings expand understanding of the spatio-temporal dynamics and exploitation of this data-limited stock, emphasizing the potential for improved population abundance estimates to inform future stock assessments. [ABSTRACT FROM AUTHOR]

Nightly images offer a special data source for monitoring fishing activities. This study used images from the Defense Meteorological Satellite Program (DMSP)/Operational Linescan System (OLS) to analyze the early development of lit fisheries in the open South China Sea (SCS), which mainly occurred around the Zhong Sha and Xi Sha Islands. Based on peak detection and a fixed threshold, lit fishing positions were extracted well from filtered, high-quality DMSP/OLS images. The results indicated that fisheries experienced an apparent rise and fall from 2005 to 2012, with the numbers of lit fishing boats rising to a maximum of ~60 from 2005 to 2008, almost disappearing in 2009, peaking at ~130 from 2010 to 2011, and starting to decline in 2012. The fish price of major fishing targets declined by ~60% in 2009, which obviously impacted the year's fishing operations. The reason for declined fishing operations in 2012 was that most of the lit fishing operations shifted farther south to fishing grounds around the Nan Sha Islands. We also explored factors shaping the distribution patterns of lit fisheries by using MaxEnt models to relate fishing positions to environmental variables. Major environmental factors influencing the distribution of lit fishing boats varied with years, of which water depth was the most important factor across years, with an optimal depth range of 1000–2000 m. In addition to depth, the distribution of lit fisheries was also influenced by SST, especially for the years 2005–2008, and a suitable SST was found between 26 and 28 °C. This study fills the knowledge gaps of the inception of lit fisheries and their dynamic changes in the SCS. [ABSTRACT FROM AUTHOR]

Summary: Excessive consumption of seafood has resulted in a decline in fish stocks and the destruction of ecosystems worldwide. Textured vegetable proteins (TVPs) can be used in manufacturing fish products, including surimi‐based fish cakes, to prevent these problems. In this study, we aimed to incorporate TVP into fish cakes as an alternative to fish meat (surimi). Fish cake samples containing TVP (0, 5%, 10%, 15% and 20%) were prepared and cooked through boiling or frying. Texture profiles, volatile compounds and consumer acceptance of the fish cake samples were measured. An increase in TVP content enhanced the protein content of the samples, making them more suitable than fish meat is as a protein source. In the fish cake samples, the textural properties, including hardness, springiness, cohesiveness, gumminess and chewiness, increased with increasing TVP content. Analysis of the volatile compounds showed that hexanal and 2‐pentifuran, which are primarily responsible for the grassy or beany flavour of soy, increased with increasing TVP content in fish cakes. The levels of these components were significantly lower in the fried samples than in the boiled samples. Overall, fried fish cakes containing 5% TVP (FST5) exhibited acceptance ratings similar to those of the control. Moreover, FST5 scored the highest in appearance, odour, taste and overall liking. Therefore, fried fish cakes supplemented with 5% TVP were qualitatively similar to fried fish cakes containing 100% fish meat (surimi). We propose the partial substitution of fish meat with alternative products to potentially reduce overfishing. [ABSTRACT FROM AUTHOR]

Marine elapid snakes are a diverse, predominantly Indo‐West Pacific species group. The persistent removal of some species has an unquantified but potentially dire impact on populations. We conducted the first comprehensive review of the trade in marine elapid snakes based on published literature (1974–2022) and trade data from the only species (i.e., Hydrophis [Lapemis] curtus) whose trade is monitored internationally. Some species and populations were subjected to targeted harvest for their meat and skins for at least the last century; fisheries are possibly the most significant threat to populations of marine elapids, with the highest numbers being exploited either accidentally, incidentally, or opportunistically in Southeast Asian fisheries targeting other seafood, including demersal trawl and squid fisheries. Southeast Asia is the core region for exploitation of marine elapids. Annual offtake is >225,000 individuals of at least 8 species in the Gulf of Thailand. Of 72 recognized marine elapids (all non‐CITES [Convention on International Trade in Endangered Species of Wild Fauna and Flora] species), Hydrophis curtus and Hydrophis cyanocinctus dominate the skin trade. Skins of H. curtus are traded mainly in East and Southeast Asia and, to some extent, Europe. Despite some baseline information on the trade of these species, the sustainability of their harvests, particularly in the context of the burgeoning and unmanaged nature of fisheries in the region, remains the major challenge. In an era of declining fish stocks, there has been an increasing trend to commercialize the harvest and use marine elapids that were once considered accidental bycatch and discarded. This trend will continue to pose a significant risk to these snakes unless appropriate fisheries and trade regulations are enforced. Applying the precautionary principle to prevent the overexploitation of sea snakes is an indispensable measure in which trade in regional populations should be regulated through CITES. Accordingly, management plans to identify core distribution regions of exploited species would be crucial for assigning national responsibilities to sustain species and populations in the long term. [ABSTRACT FROM AUTHOR]

The Eurasian otter, Lutra lutra, faced adversity in Europe in the 1950s and 1960s due to hunting, declining fish populations and the American mink invasion. Slow recovery since the 1970s led to a 'Near Threatened' in the IUCN Red List status, but recent pollution, fishing pressure and habitat loss caused slight population declines. Otters, known for aquatic habits, are mainly piscivorous and exhibit solitaire or social behaviours. Infanticide with parent‐offspring cannibalism has been previously reported in otter species, but although cannibalism has been suggested, it has not been documented before. This study presents the first documented case of cannibalism among free‐living Eurasian otters observed in northern Norway. Some authors described cannibalism as an opportunistic resource‐efficient behaviour in several mammal species, offering benefits like weight gain and reduced competition, challenging the view of adverse health effects. Factors leading to otter cannibalism include ecological changes, resource competition with other species and global warming and overfishing practices contributing to increased otter competition. Further studies will be vital to answering intriguing questions about the implications of cannibalism for otter conservation. [ABSTRACT FROM AUTHOR]

Human–wildlife conflict is often a driver of species declines, and understanding the material basis of this conflict is the first step in addressing it. The Titicaca Grebe Rollandia microptera is an endangered endemic species found solely in the Lake Titicaca watershed of Peru and Bolivia, and has experienced population declines due to fisheries bycatch. Human fishers often have negative opinions of the Titicaca Grebe, because they consider it as a competitor for declining fish stocks. We tested that assumption by an analysis of the bird's diet and found that the Titicaca Grebe does not compete with fishers for more lucrative fish species such as trout Oncorhynchus sp. and Pejerrey Odontesthes bonariensis, but does compete for the less desirable (to human fishers) native Orestias sp. [ABSTRACT FROM AUTHOR]

Policies aiming to restore ecosystems, achieve thriving fisheries and reverse biodiversity loss require knowledge of their former status and long‐term variation. As quantitative fish data is typically only available for recent decades long after changes may have occurred, a greater use of qualitative sources has been encouraged in marine historical ecology. We examined diverse historical information (including maritime history, fisheries reports, naturalists' accounts, recipes, nautical charts and newspapers) across a multi‐century time span (13th–20th century) for a wide range of species to document their long‐term trajectories in an understudied Northeast Atlantic ecosystem (Irish Sea coast of Wales). We find strong evidence of the loss of both a pelagic fishery for herring, which was of fundamental socio‐ecological importance since at least the 13th century, and the loss of significant multi‐species demersal and intertidal fisheries. Local, commercial and/or functional extinction has occurred for taxa spanning a wide range of diversity (crustacean, elasmobranchs, sturgeon, and teleosts), body size and ecological role, suggesting far‐reaching changes to food webs. This raises fundamental questions about the present‐day health and integrity of this coastal ecosystem and the long‐term viability of current fisheries which depend on a few shellfish species. Our century‐scale synthesis of qualitative data for multiple taxa allows the collective breadth of losses to be fully appreciated and may reduce the risk of 'shifting baselines'. Restoration to historical baselines may not be achievable, but our findings provide evidence of long‐term change relevant to policies for recovery, and prevention of further decline of fishes, fisheries and ecosystems. [ABSTRACT FROM AUTHOR]

It is essential to explore alternative and advantageous additives due to the essential requirement for ensuring the safety and well-being of aquatic animals. The present study investigated the role of Lactobacillus helveticus (Lh) and chlorogenic acid (CGA) on growth performance, hematology factors, digestive capacity, antioxidant activity, and stress in tissue prior and post-exposure to heat shock on common carp (Cyprinus carpio). For this purpose, 240 common carp with mean weight of 23.79 ± 0.49 g were allocated into four groups (20 fish each) and fed for 56 days on 0, 10 7 CFU g-1 Lh, 550 mg kg-1 CGA, and a combination of both elements (10 7 CFU g-1 + 550 mg kg-1 CGA) (T0, T1, T2, and T3). At the end of feeding period (56 days), growth performance, hematology indexes, digestive enzymes, antioxidant enzymes, stress, and immunity factors were evaluated. Thereafter, common carp was exposed to heat shock and levels of antioxidant enzymes and stress factors were estimated. There was an observable disparity in the growth parameters among various treatments, and the most prominent level was discovered in T3. There were no significant disparities in hematology indicators (p > 0.05). The levels of trypsin, chymotrypsin, pepsin, and protease were significantly higher in common carp fed with CGA and Lh. The total protein exhibited a significant increase in common carp fed with CGA and Lh (p < 0.05). The addition of CGA and Lh had no significant impact on urea and triglyceride content (p > 0.05). The lysozyme activity, ACH50, and total immunoglobulin exhibited a significant increase in common carp when subjected to CGA and Lh (p < 0.05). The effects of CGA and Lh on catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were significant both before and after heat stress. Moreover, these effects were more pronounced in fish that were fed with supplemented diets (p < 0.05). The malondialdehyde (MDA) levels demonstrated a significant decrease among the treatments before and after the heat challenge and the lowest level of MDA was recorded in T3 during both phases (p < 0.05). The aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), glucose, and cortisol levels also showed a significant decline in fish that were fed with supplemented diets both before and after heat stress (p < 0.05). Given the importance of L. helveticus and chlorogenic acid, the incorporation of both substances exhibits a powerful synergistic effect, thereby maximizing their advantageous properties in enhancing growth efficiency, digestion, hematological profile, biochemical markers, and immune-antioxidant capacity in common carp. [ABSTRACT FROM AUTHOR]

Simple Summary: Ecological fishery management is one of the predominant approaches to lake ecological management in China; it involves the stocking of filter-feeding fish species to mitigate algal blooms. This strategy not only enhances water quality but also yields ecological benefits by fostering the growth of fish populations, thereby offering both ecological and economic advantages. Nonetheless, there is a scarcity of works in the literature addressing the effects on fish community dynamics and diversity in lakes subsequent to the cessation of ecological fishing practices. This study focuses on the initial changes observed in fish community composition and diversity following the cessation of an ecological fishery project in Qilu Lake, an eutrophic shallow lake situated in China. Ecological fishery projects aim to improve the water quality of eutrophication lakes by stocking filter-feeding fish species that feed on algae. The findings indicate a significant decline in the number of fish species, average individual size, and species diversity index following the cessation of fisheries-related activities (including fish stocking and fishing activities) due to the termination of the ecological fishery project in the lake. To preserve fish biodiversity and enhance water quality in Qilu Lake, it is recommended that policies be implemented to sustain the implementation of ecological fisheries projects, restore habitats for native fish species, and regulate the proliferation of small fish populations. The Qilu Lake is an eutrophic shallow lake located in Yunnan Province, China. An ecological fishery project was initiated in the lake from 2011 to 2021 to introduce filter-feeding fish species that feed on algae, with the aim of improving water quality. In January 2022, when the ecological fishery project expired, all fisheries-related activities (including fish stocking and fishing activities) ceased in the lake. To comprehensively evaluate the initial alterations in fish community structure and diversity resulting from the fishing cessation in the Qilu Lake, the present study conducted field surveys within the one year before the fishing cessation (referred to as BFC) and the one year after the fishing cessation (referred to as AFC). A total of twenty-one fish species were collected, including four native species. Four species were recorded in the lake for the first time, including Pelteobagrus fulvidraco, Pelteobagrus vachelli, Paramisgurnus dabryanus, and Hyporhamphus intermedius. The number of fish species decreased from 21 to 13 following the fishing cessation. The fishes collected in both BFC and AFC are mainly omnivorous-feeding and of bottom-dwelling habits. The mean size of the fishes in the AFC sample shows a significant decrease compared to those in BFC. After the fishing cessation, the Shannon–Wiener diversity index and Margalef richness index of the fish slightly declined. The fish community structure of the Qilu Lake exhibits a high degree of similarity to adjacent lakes in central Yunnan. Our study demonstrates a significant shift in the fish community of the Qilu Lake following the fishing cessation, one which may adversely impact the stability of the lake ecosystem. To enhance fish species diversity in the Qilu Lake, it is recommended that policies be implemented to promote the ecological fishery project and improve habitat restoration for native fish species, while also regulating fish community structure. [ABSTRACT FROM AUTHOR]

Population genetic analysis of invasive populations can provide valuable insights into the source of introductions, pathways for expansion, and their demographic histories. Flathead catfish (Pylodictis olivaris) are a prolific invasive species with high fecundity, long‐distance dispersal, and piscivorous feeding habits that can lead to declines in native fish populations. In this study, we analyse the genetics of invasive P. olivaris in the Mid‐Atlantic region to assess their connectivity and attempt to reconstruct the history of introduced populations. Based on an assessment across 13 microsatellite loci, P. olivaris from the Susquehanna River system (N = 537), Schuylkill River (N = 33), and Delaware River (N = 1) have low genetic diversity (global Hobs = 0.504), although we detected no evidence of substantial inbreeding (FIS = −0.083 to 0.022). P. olivaris from these different river systems were genetically distinct, suggesting separate introductions. However, population structure was much weaker within each river system and exhibited a pattern of high connectivity, with some evidence of isolation by distance. P. olivaris from the Susquehanna and Schuylkill rivers showed evidence for recent genetic bottlenecks, and demographic models were consistent with historical records, which suggest that populations were established by recent founder events consisting of a small number of individuals. Our results show the risk posed by small introductions of P. olivaris, which can spread widely once a population is established, and highlight the importance of prevention and sensitive early detection methods to prevent the spread of P. olivaris in the future. [ABSTRACT FROM AUTHOR]

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Fish stocks are declining in marine capture coastal fisheries in West Africa. Many observers have blamed climate change and the system of open access for the decline. Open-access fishing encourages too many people to take up fishing, and the result is overfishing of the stocks. According to such critics, this is a classic example of Hardin's tragedy of the commons, whereby a continuous increase in the number of users of a natural resource eventually leads to the collapse of the resource. The present study, which analysed stakeholders' perceptions about their open-access fishing in Siera Leone's marine fisheries, conducted 32 key informant interviews. Our research found that while they perceived that open-access fishing impacted fish stocks, most Sierra Leone's marine capture fishers did not see open access as a cause of fish decline; instead, they blamed the lack of enforced regulations on the methods and extent of fishing. Accordingly, these fishers favoured the continuation of open access—not least because it helps to alleviate hunger and is a readily available source of protein in Sierra Leone's coastal communities—but accompanied by strict regulations on both the type of fishing gear used and the quantity, size, and species of fish caught. In other words, they preferred regulated open access to unregulated open access. The central government's resolve to regulate its fishery will determine whether it will transition from unregulated open access to regulated open access or other forms of OA. This study recommends detailed research into how to influence political will to enforce regulations. [ABSTRACT FROM AUTHOR]

Fish production from natural resources has been facing countless challenges, primarily pollution, excessive fishing effort, unlawful gathering of fish fry in addition to food accessibility. Suez Canal lakes, Bitter and Timsah lakes are among the essential lakes in Egypt, producing commercial species with a mean annual fish production of 4000 tons (2005-2021). In the last 17 years, a severe decline in the fish production from the Suez Canal lakes was recorded. Fishery statistics of the Suez Canal lakes were collected from 2005 to 2021 to track the total catch, bivalve catch, and fishing effort during that period. Sediment and water samples were collected at 24 stations around the Great Bitter and Timsah lakes during 2022 and 2023. The grain size analyses designated that the bottom sediments of the Suez Canal lakes were principally composed of sand, with minor ingredients of gravel and mud. The concentration of heavy metals revealed that Fe has the highest concentration in the water and sediments of both lakes, while that of Cd was the lowest. The soft tissues of 105 individuals of Paphia undulata (Born, 1778), 100 individuals of P. textile (Gmelin, 1791) and 200 individuals of Donax trunculus (Linnaeus, 1758) from Lake Timsah were used for assessing heavy metal concentrations. Results showed that the concentration of all metals in the soft edible parts of the considered bivalve species were within the safe levels, except for lead (Pb) and zinc (Zn) that recorded higher levels than the permissible ones. A production model was used to evaluate the fishery status of the studied species in the Bitter and Timsah lakes. Based on the results, the main reasons for the production depletion of the studied species in the Suez Canal lakes are the overfishing and pollution. Therefore, the fishing effort control and pollution mitigation are strongly recommended in the lakes. [ABSTRACT FROM AUTHOR]

Fishing is an essential economic activity and source of livelihood for millions of people worldwide. However, overfishing and unsustainable practices have led to a decline in fish populations and the degradation of marine ecosystems. Moreover, fishing activities can contribute to climate change through the emission of greenhouse gases (e.g., carbon dioxide and methane) from fishing vessels and seafood transportation. To mitigate the environmental impacts of fishing activities, sustainable fishing practices must be implemented to minimize the negative impacts of fishing on the environment while maintaining the productivity and diversity of fish populations and ecosystems. These practices include using selective fishing gear, avoiding fishing in vulnerable habitats, implementing fishery management plans, and reducing the carbon footprint of the fishing industry. To this end, and as a first step in defining efficient and effective measures towards the sustainability of capture fishing activity, an analysis of the environmental sustainability of the Galician fishing sector, one of the main European regions in this field, is presented in this work. An ecosystem-based indicator (ecological footprint, calculated by adding the so-called fishing ground footprint and the carbon footprint) was employed to quantify the main impacts of capture fishing during extractive activity. The catch composition and fuel consumption of the fleet based on the vessels' power, and economic benefits, were the parameters used in this analysis. The results showed that ports with larger vessels and fleets seem to be more eco-efficient than those concentrating smaller vessels in targeting lower trophic level species. [ABSTRACT FROM AUTHOR]

The fish industry is an important source of income for island countries. Fish is a main source of animal-based protein. Marine fishing is gradually being replaced by marine farming (or aquaculture) due to declining wild fish populations and water pollution. However, fish farming is costly job with high requirements for labor, electricity, water, and feed. The use of deep learning to perform intelligent surveillance in aquaculture fields, reducing the need for human resources and implementing real-time monitoring, has been proposed. In this article, we propose a novel deep residual network (ResNeXt $3 \times 1 \mathrm{D}$) for abnormal behavior recognition in aquaculture fields. The proposed ResNeXt $3 \times 1 D$ convolutional network is mainly based on an $R(2+1) D$ convolutional network and modified to obtain better performance. Experimental results showed that the proposed ResNeXt $3 \times 1 D$ exhibited good performance for abnormal behavior recognition in aquaculture fields. Specifically, the accuracy obtained using the proposed ResNeXt $3 \times 1 \mathrm{D}$ for abnormal behavior recognition in aquaculture fields was approximately $95.3 \%$. [ABSTRACT FROM AUTHOR]

Lake Chala straddles the Kenya–Tanzania border, with a narrow strip of terrestrial habitat around it. The steep rocky shores are bedecked in a backdrop of Kilimanjaro at sunrise, giving the area the aesthetic beauty of an important tourist destination. The lake has important conservation implications ranging from endemic species including a critically endangered and rapidly declining fish to other unique biodiversity. This calls for urgent action to prevent extinction and promote sustainable management, building on previous work and action plans such as a proposed new conservancy, as the best safeguard against the threats. [ABSTRACT FROM AUTHOR]

Animal movements and resource utilization are essential factors for effective environmental management, but they are difficult to quantify in extensive natural ecosystems such as the aquatic environment.Stable isotope analysis is an ecological tracer technique that reveals information about links between trophic levels, movement patterns of migratory species or geographical variations due to the different aquatic processes that influence them. The Caspian kutum is an important commercial endemic species on the southern coasts of the Caspian Sea and can be used as a proxy to gain information on how different spatiotemporal, environmental and biological—variables can influence ecological tracers such as stable isotopes at the sea basin level. Thus, the main objective of this study is to investigate how spatiotemporal, isotopic baseline and environmental factors influence the distribution of stable isotopes in the Caspian kutum.The results showed that although there are individual variations, there is an overall increasing trend in δ13C and a decreasing trend in δ15N from the western to the eastern regions. In addition, there is a decreasing trend in δ13C and an increasing trend in δ15N with increasing age. It seems that among other migration routes of this species from the northern part of the southern Caspian Sea to the southern coasts, one of the main migration routes of this fish on the coasts of Iran is west‐east mobility, which may affect the efficiency of sustainable management of the catch in various fishing areas.This was the first study to establish a migratory pattern of the Caspian kutum based on stable isotopes. We advocate the wider stable isotopes to effectively investigate fish migratory, as the results from this study provided important contributions to the development of valuable insights for the management and sustainability for this threatened and declining species fish populations. [ABSTRACT FROM AUTHOR]

As one of the world's most regulated river basins, the semi-arid Murray–Darling Basin (MDB) in south-eastern Australia is considered at high ecological risk, with substantial declines in native fish populations already identified and climate change threats looming. This places great importance on the collection and use of data to document population trends over large spatial extents, inform management decisions, and provide baselines from which change can be measured. We used two medium-term data sets (10 MDB basin-wide fish surveys from 2004–2022) covering the 23 catchments and 68 sub-catchments of the MDB to investigate trends in the distribution of common riverine species at the entire basin scale. Fifteen native species were analysed for changes in their contemporary range, and whilst short-term changes were identified, all species showed no significant continuous trend over the study period. We further analysed the native species extent relative to their historic records, with bony herring and golden perch occurring in 78% and 68% of their historic river kilometres, respectively, whereas southern pygmy perch, northern river blackfish, silver perch, mountain galaxias, and freshwater catfish were all estimated to occur in less than 10% of their historic extent. Six established non-native species were also analysed and were very consistent in extent over the years, suggesting that they are near the available limits of expansion of their invasion. We provide effect sizes for the spatial extent index which can be used as baselines for future studies, especially those aiming to monitor changes in the spatial extent and population status of native species, or changes in the spatial extent of new or existing non-native species. [ABSTRACT FROM AUTHOR]

Across the globe, fish stocks have been in decline due to industrialization of fisheries resources, overfishing, pollution, and climate change, thereby warranting more fisheries assessments. The floodplain fishery of Tonle Sap Lake near the Kampong Khleang stilted community in the Chamkar Youn village in Cambodia was evaluated by: (1) characterizing fish assemblage structure and function, (2) highlighting temporal differences in fish assemblage, and (3) assessing potential indicators of fishing‐down‐the‐food‐web by the fishery. Fish trap data from the wet season were used to characterize fish abundance, diversity, species richness, and functional feeding guilds from fish catches in 2014 and 2019. Fish abundance declined 62% and species richness declined between 2014 and 2019. Smaller‐bodied, lower‐trophic level fishes dominated the catch. Our limited findings add insight into the status of a globally important fishery and highlight the need for more local collaborative fishery assessments. [ABSTRACT FROM AUTHOR]

Globally, suitable freshwater habitats are undergoing alterations and fish population declines, primarily attributed to the swift changes in climate and land use. Developing an effective conservation policy for freshwater fish necessitates careful consideration of the impacts of climatic and spatial factors. This study focuses on the analysis of 64 threatened freshwater fish in Bangladesh to anticipate their current and future climatically suitable habitats, utilizing the bioclim() species distribution model. Additionally, this study examines existing inland hydrographic networks and their corresponding harvest rates. The findings indicate that approximately 75% of the area of occupancy for the studied species is currently climatically suitable, but this is expected to decrease to 13% under future climate scenarios. Notably, 27 threatened species are at risk of lacking climatically suitable habitats in the future within their current area of occupancy. The three components of hydrographic networks—floodplains, rivers, and natural lakes—play varying roles in providing a climatically suitable habitat for the studied species. For instance, only 34% of threatened fish species are projected to find a suitable habitat over flood areas, 23% over rivers, and 16% over lakes. Existing protected areas presently offer limited protection (21% suitable area), expected to decline to 6% in the future, with no dedicated protected areas for freshwater fish. Floodplains are highlighted for providing habitat connectivity and facilitating brood fish dispersal. However, the unregulated and unmonitored annual harvest of freshwater fish from floodwater and rivers poses a potential silent cause for rapid population decline. Prioritizing the management of hydrographic components to maintain habitat connectivity, legal protection for threatened fish species, and establishing permanent protected areas for fish are crucial aspects in developing a conservation policy to mitigate the impact of future climate scenarios on threatened freshwater species. [ABSTRACT FROM AUTHOR]

Astyanax caucanus is an endemic fish species to the Magdalena-Cauca basin in Colombia. It is considered a Least Concern species by the International Union for Conservation of Nature, and currently, it is not a fishery resource. Its fertilized eggs may drift up to 4–5 days before hatching and can be carried up to 340 km given the water velocity of the river. Although A. caucanus is listed as short -migratory species (< 50 km), this study hypothesized that it exhibits gene flow along the middle and lower section of the Cauca River due to the great potential for larval dispersal. To test this hypothesis, we developed a set of species-specific microsatellite primers suitable for population genetic studies. Genetic structure analyses with 193 samples evidenced two genetic stocks that coexist, comigrate, and exhibit gene flow along the study area. Both stocks show high genetic diversity indices (Na and HE) and effective population sizes (Ne > 1000), but also show evidence of bottlenecked populations and high values of the inbreeding coefficient (FIS). Finally, these results are useful to understand the effects of other anthropic activities, besides fishing pressure on population bottlenecks found for other fish species cohabiting the area. [ABSTRACT FROM AUTHOR]

Information on the feeding habits of the critically endangered Irrawaddy dolphin (Orcaella brevirostris) in the Mekong River and how their diet overlaps with that of the species targeted by fisheries is limited. The information provided herein will be helpful for evaluating and protecting important dolphin food resources. The composition of large prey species of Irrawaddy dolphins and the extent of fish resources were surveyed in the Mekong River, Cambodia, using local ecological knowledge. The results showed that Irrawaddy dolphins fed on 13 species of large fish, with Pangasius conchophilus, Cyclocheilichthys enoplos, and Hemibagrus wyckii the most frequently consumed prey. Twelve of the 13 reported prey species were usually caught by fishers. The results also revealed that the average weight of fish caught daily by fishers was significantly lower in 2019 than about five years before that, regardless of the season. A significant decline in fish resources and a high overlap of dolphin diets with fishery target species indicate that Irrawaddy dolphins may also be threatened by prey depletion, especially during the dry season when dolphins are concentrated in deep pools. [ABSTRACT FROM AUTHOR]

Behavioural interactions between alien invasive fishes and native fishes is considered one of the drivers of native fish decline. However, there are few experimental studies on their behavioural interactions at the individual level. In this study, we investigated the behavioural interactions between the threatened native killifish Valencia letourneuxi, and the alien invasive Eastern mosquitofish Gambusia holbrooki, thought to induce the killifish's rapid population decline. The aim was to assess aggressive behaviours, disruption in activity, stress levels, boldness, forging efficiency and shelter use by the native fish in the presence of the mosquitofish. Interspecies interactions were assessed in a three-tiered experimental setup, i.e. in an empty arena, in the presence of an artificial cover, and during feeding, using two opponents at each trial. The behaviours recorded and assessed were nips, following, approach, moving/immobile, top/bottom, erratic movement, cover use, feeding and latency to exit. The results showed that the mosquitofish was bolder, followed the native species, spent significantly less time under the cover and consumed food, as opposed to no following by the native species, significantly higher cover use and time immobile, as avoidance behaviours, and zero feeding in the presence of the mosquitofish. More significantly, the native species received direct aggression by the mosquitofish, as opposed to no aggression at all exhibited by it. Future research needs, as well as the conservation implications of our findings are briefly discussed. [ABSTRACT FROM AUTHOR]

Conservation planners often rely on heuristic indices when challenged with prioritizing potential projects under a constrained budget. This paper presents a comparative analysis of several prioritization indices (PIs) of culvert fish passage barriers, which can contribute to declines in anadromous fish populations. A federal injunction requires Washington state to restore 90% of habitat blocked by state‐owned culverts by 2030, prompting the development of numerous PIs, by various entities (i.e., counties, cities) within the injunction area. Our comparative analysis of PIs within the injunction Case Area investigates their ability to distinguish between barriers, their transferability in terms of scoring metrics, how scoring weights differ, and the preferences implied thereby. We document the use of six distinct PI methods by 10 entities and find that some PIs used many shared metrics, whereas others used a high percentage of unique metrics that would be difficult to replicate outside the entity's jurisdiction. Although habitat potential, habitat quantity, and connectivity were considered across all PIs, we found a high level of variation in terms of the metric weights. Our methods can be employed in other geographies or for other restoration PI planning efforts, and our results may facilitate the development and refinement of future PIs. [ABSTRACT FROM AUTHOR]

Use of phytobiotics as immunostimulant is increasing in aquaculture. In this study, the immune and growth promoting effects of parsley extract (PUE) were examined in the rainbow trout. In this regard, the various dietary levels of parsley extract (PUE), Petroselinum crispum (0, 0.5, 1.5, 3, and 4.5%) was added to the diet of rainbow trout to assay its potentials on immunity, growth, digestive enzymes, and mitigating ammonia-induced stress. A total of 450 fish (15.43±0.06 g; mean ± SE) were distributed into fifteen 300-L fiberglass tanks (30 fish per tank) and fed PUE for 60 days and then challenged with unionized ammonia (0.3 mg/l). According to results, PUE mainly at 3−4.5% levels increased the growth, lipase and protease activities, humoral and mucosal immune components and liver antioxidant enzymes activities. These effects were kept even after ammonia stress, where the immune components were higher in PUE-treated fish than the control group. Furthermore, the dietary PUE reduced ammonia-related oxidative stress, as malondialdehyde (MDA) values (as the indicator of lipid peroxidation) decreased in fish fed PUE. The concentrations of liver metabolic enzymes in blood, both before and after ammonia stress declined in the fish fed PUE. Our findings demonstrated the growth and immune boosting and ammonia-stress mitigating properties of PUE in rainbow trout. [ABSTRACT FROM AUTHOR]

With increasing intensive aquaculture production, the search for nourishing, environmentally, and economically viable fishmeal (FM) alternative is an endless approach. Therefore, the present study examines the effect of the use of black soldier fly, Hermetia illucens, larvae meal (BSFM) as an alternative protein for FM in the diet of Nile tilapia, Oreochromis niloticus, on nitrogen wastes, zootechnical performance, body composition, and hematobiochemical parameters. A total of 315 Nile tilapia fingerlings (4.11±0.12 g/fish) were divided into seven treatments in triplicate. The fish were stocked in glass aquaria (50 × 40 × 30 cm; 60 L each) at a rate of 15 fish per aquarium. Experimental diets contained BSFM at increasing levels of 0, 5, 10, 15, 20, 25, and 30% as FM replacers were offered twice daily to apparent satiation for 84 days. The results revealed that BSFM replacements significantly (P = 0.001) enhance water quality and reduce the total ammonia, NH3, and NO2 levels compared to the control. The growth performance, feed conversion ratio, and survival were improved with increasing BSFM meal inclusion levels up to 25% (P = 0.001, 0.017, and 0.001, respectively). However, the zootechnical performance of the experimental fish started to decline with increasing replacement levels to 30%. Also, by an increase in BSFM level to 25%, hematobiochemical markers were considerably (P≤0.01) enhanced. The liver and kidney function indicators improved (P = 0.001) with dietary BSFM. The economic evaluation revealed that feed costs and fish weight gain were decreased by increasing BSFM levels in fish diets. The current study highlighted the potential environmentally beneficial use of BSFM as an FM replacer in terms of reducing water nitrogen waste levels and improving growth performance, health status, and enhancing the economic feasibility of the commercial tilapia diet. [ABSTRACT FROM AUTHOR]

This paper underscores the benefits of employing data visualization and geostatistical analyses in monitoring the water quality parameters of Laguna Lake in the Philippines, particularly emphasizing the influence of quarterly seasonality based on the Philippine climate. Preliminary post-COVID-19 lockdown analyses support and extend the literature in highlighting the persistent risks posed by population growth and industrialization of Metro Manila, also known as the National Capital Region, to the ecosystem and economic benefits of the lake. While findings corroborate existing studies, this paper proposes novel avenues for future research, pinpointing locations with elevated water quality parameters and exploring the impact of different seasonal quarters in the Philippines. The findings also offer potential contributions to Sustainable Development Goal 6 and proactive climate change responses. Targeting stakeholders, economic managers, and health officials overseeing Laguna Lake, the study provides a foundation for informed decision-making and anticipatory measures crucial for addressing potential fish population declines, especially during warmer seasons. Contiguity in Metro Manila raises concerns about water quality, necessitating decisive interventions to mitigate long-term human and fish health risks from contaminant accumulation. Integrating the Geographical Information System enhances interpretation by revealing clusters of high or low water quality parameter values, empowering effective resource management. Further, identifying the hot spots of the water quality parameters by seasonal quarter may equip authorities with essential insights for safeguarding the sustainability, economic vitality, and well-being of the dependent populations of the lake on ways forward after the COVID-19 lockdowns were fully lifted. [ABSTRACT FROM AUTHOR]

Fishes exhibit a diverse range of traits encompassing life‐history strategies, feeding behaviours and spawning behaviours. These traits mediate fish population responses to changing environmental conditions such as those caused by anthropogenic stressors. The Conasauga River, located in northwestern Georgia and southeastern Tennessee, USA, hosts a diverse assemblage of over 75 species of freshwater fish, some of which are locally or regionally endemic, and many of which are imperilled. Annual monitoring data have shown population declines in multiple fish species of conservation concern in the Conasauga River since at least the 1990s, raising the possibility that other taxa could be declining as well. We quantified temporal changes in fish communities at six shoal sites sampled annually in most years from 1996 to 2022, and asked whether species traits hypothesized to underlie population vulnerability to environmental alteration were correlated with species‐specific trends for 32 taxa. We estimated that total counts of fish in annual samples declined by ~2% per year, although declines were uneven among species and generally greater for less abundant taxa. Tests for species traits corresponding to temporal population trends provided evidence that crevice‐spawning minnows and smaller‐bodied taxa had steeper declines compared with broadcast spawners and larger, longer‐lived, more fecund taxa. Lower abundance, reliance on a particular habitat feature, and life‐history traits that may limit population resilience to disturbance may all prove useful for identifying riverine fishes at particular risk of future population decline. [ABSTRACT FROM AUTHOR]

The California Central Valley steelhead (Oncorhynchus mykiss) has declined precipitously since Euro-American colonization and has been listed as threatened under the United States Endangered Species Act since 1998. Hatchery-origin fish now dominate the population, and hatchery management is a key listing factor. However, scant release metric information is available. We compiled a time series of O. mykiss hatchery release data for all four Central Valley hatcheries releasing O. mykiss between 1948 and 2017. The biocomplexity of released fish has declined since the early 1980s. Individuals have been released at increasingly similar numbers, biomass, body sizes, times, and locations over time. Moreover, yearling fish have been released at larger sizes, leading to the near-exclusive release of age-1 smolts in February and March since the late 1990s and early 2000s. Pervasive reductions in release portfolios have likely occurred for other hatchery-supported Pacific salmonid stocks throughout the Pacific Rim region. In an increasingly variable environment, such reductions in intraspecific diversity could significantly affect population stability and resilience. [ABSTRACT FROM AUTHOR]

We used the bycatch of Caspian sturgeon to quantify the species composition, length structure, spatial and temporal distribution, temporal dynamics of relative abundance (indexed as catch‐per‐unit‐effort, CPUE), effects of fingerlings released, and to forecast future sturgeon stock status. Dynamic factor analysis of temporal changes in species CPUE was used to quantify relationships to environmental variables (sea surface temperature, chlorophyll‐a, sea surface level, and river discharge) during 2006–2022. We found that the Guilan subarea had the lowest relative abundance and differed from all other subareas. Fish abundance was highest in October and November, particularly in Mazandaran and Golestan coastal waters. Relative fish abundance declined significantly over time. Acipenser persicus was the most abundant species, followed by Aciperser gueldenstaedtii, Aciperser stellatus, Aciperser nudiventris, and Huso huso. The annual number of fingerlings released decreased during 2000–2021. Over the years, environmental variables such as sea surface level, sea surface temperature, and chlorophyll‐a showed different trends, with sea surface temperature generally increasing, chlorophyll‐a generally decreasing, sea surface level decreasing nearly linearly, and river discharge varying erratically without a trend in the southern Caspian Sea during 2006–2022. The relative abundance of all species decreased and was significantly related to sea surface level. Fish abundance was forecasted to decline by 2025, as sea surface temperature increases and sea surface level decreases. Illegal, unreported, and unregulated (IUU) harvest of sturgeon must be effectively regulated to ensure the survival and recovery of sturgeon populations in the Caspian Sea. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyse the development of artisanal fish catch by species in the Croatian section of the Sava River. For Abramis brama and Silurus glanis, a significant decline in catches (in kg) was observed throughout the study period (2004-2021). Since 2013, this has also been the case for Cyprinus carpio, Esox lucius, Sander lucioperca, other autochthonous species and alochthonous species, while catches of Leuciscus idus have declined significantly since 2014. The catches of three species (Acipenser ruthenus, Leuciscus aspius and Tinca tinca) fluctuated without a trend, which can be attributed to the low quantities. This decline in catches of the most sought-after species in the Sava was greater than that of the other less sought-after autochthonous species (mainly other cyprinids), whose share of the total catch increased significantly. [ABSTRACT FROM AUTHOR]

World Fish Migration Day is a global event that aims to raise awareness about the connections between migratory fish and human and nonhuman species, lands, and waters. The event highlights the importance of free-flowing rivers for migratory fish populations and emphasizes their role in supporting healthy ecosystems and livelihoods. Over the past ten years, various activities such as river clean-ups, fish viewings, and artistic workshops have been organized to celebrate World Fish Migration Day. The COVID-19 pandemic temporarily halted events in 2020, but some celebrations were able to take place later in the year. [Extracted from the article]

Since salmon lice have developed resistance to pesticides, non-medicinal delousing treatments have become increasingly used to remove the parasite from fish on salmon farms in Norwegian waters. These novel techniques are an important means of controlling epidemics of lice at farms for maintaining the health of farmed fish and for preventing the spread of lice to wild salmonid populations. However, some treatments are associated with higher mortality rates and negative welfare impacts on the host fish. Furthermore, it is unclear how effective each treatment is in removing lice compared to alternatives. Here, in a controlled laboratory environment, we tested the efficacy of mechanical, warm water (28 °C and 34 °C), and freshwater treatments alone and in combination, and examined their welfare impact on host fish. Regardless of treatment group or control, the handling of fish through the experiment led to a reduction in lice load and decline in fish welfare. Among the treatments examined, the freshwater bath alone and in combination with other treatments had the greatest delousing efficacy. The 34 °C warm water baths also significantly reduced lice loads but led to worse welfare outcomes with fish having a higher prevalence of injuries and reduced growth and condition factor. Delousing treatments were however not associated with long-term effects on neuroendocrine parameters or stress coping ability, suggesting that immediate welfare impacts from these procedures are generally reversible. It was also found that sedating fish prior to treatment was shown to mitigate the welfare impact. These findings are useful for the needed optimization of delousing strategies for greater delousing efficacy and reduced welfare impact on fish. [ABSTRACT FROM AUTHOR]

Fish hatcheries are widely used to enhance fisheries and supplement declining wild populations. However, substantial evidence suggests that hatchery fish are subject to differential selection pressures compared to their wild counterparts. Domestication selection, or adaptation to the hatchery environment, poses a risk to wild populations if traits specific to success in the hatchery environment have a genetic component and there is subsequent introgression between hatchery and wild fish. Few studies have investigated domestication selection in hatcheries on a genomic level, and even fewer have done so in parallel across multiple hatchery–wild population pairs. In this study, we used low‐coverage whole‐genome sequencing to investigate signals of domestication selection in three separate hatchery populations of Chinook salmon, Oncorhynchus tshawytscha, after approximately seven generations of divergence from their corresponding wild progenitor populations. We sequenced 192 individuals from populations across Southeast Alaska and estimated genotype likelihoods at over six million loci. We discovered a total of 14 outlier peaks displaying high genetic differentiation (FST) between hatchery–wild pairs, although no peaks were shared across the three comparisons. Peaks were small (53 kb on average) and often displayed elevated absolute genetic divergence (Dxy) and linkage disequilibrium, suggesting some level of domestication selection has occurred. Our study provides evidence that domestication selection can lead to genetic differences between hatchery and wild populations in only a few generations. Additionally, our data suggest that population‐specific adaptation to hatchery environments likely occurs through different genetic pathways, even for populations with similar standing genetic variation. These results highlight the need to collect paired genotype–phenotype data to understand how domestication may be affecting fitness and to identify potential management practices that may mitigate genetic risks despite multiple pathways of domestication. [ABSTRACT FROM AUTHOR]

Predicting and measuring changes resulting from marine protected areas (MPAs) has posed a challenge for practitioners, partly because ecosystems are complex and can change in unanticipated ways, but also due to MPA characteristics such as design factors, conservation objectives (COs), and monitoring programs, that can leave little chance of meeting stated goals. We consider these design factors for the Laurentian Channel MPA, a large offshore Canadian protected area established to protect against fishing impacts. Specifically, in this study we evaluated (1) whether it is realistic to expect improvements in the MPA for four previously established taxa‐specific COs, and (2) whether existing scientific surveys are capable of detecting changes in these CO taxa even if they occurred. Three CO species were sampled in scientific multispecies research vessel trawl surveys (Black Dogfish, Smooth Skate, and Northern Wolffish) and a fourth CO, sea pen taxa, were enumerated using seafloor imagery. Simulations indicate that trawl surveys have very little chance of detecting change in the abundance of the three fish species examined, while seafloor imagery data had higher statistical power for sea pen taxa. Moreover, we show that expecting change related to the removal of fishing is unrealistic due to the fact that the MPA was established in an area of minimal fishing pressure. While positive change is unlikely to be induced by the MPA, or be detected if they occurred, this MPA could provide conservation benefits if COs and monitoring approaches were realigned to match the unique features of this area that represents largely unimpacted sensitive benthic habitats. [ABSTRACT FROM AUTHOR]

Under climate change, model ensembles suggest that declines in phytoplankton biomass amplify into greater reductions at higher trophic levels, with serious implications for fisheries and carbon storage. However, the extent and mechanisms of this trophic amplification vary greatly among models, and validation is problematic. In situ size spectra offer a novel alternative, comparing biomass of small and larger organisms to quantify the net efficiency of energy transfer through natural food webs that are already challenged with multiple climate change stressors. Our global compilation of pelagic size spectrum slopes supports trophic amplification empirically, independently from model simulations. Thus, even a modest (16%) decline in phytoplankton this century would magnify into a 38% decline in supportable biomass of fish within the intensively-fished mid-latitude ocean. We also show that this amplification stems not from thermal controls on consumers, but mainly from temperature or nutrient controls that structure the phytoplankton baseline of the food web. The lack of evidence for direct thermal effects on size structure contrasts with most current thinking, based often on more acute stress experiments or shorter-timescale responses. Our synthesis of size spectra integrates these short-term dynamics, revealing the net efficiency of food webs acclimating and adapting to climatic stressors. Using a global synthesis of size spectra data from pelagic food webs, this study finds that size structure is not driven by temperature as often suggested, but by the nutrient status of the system. This means that modest phytoplankton declines projected for key fishing grounds at mid-latitudes will amplify into substantial reductions in the supportable biomass of fish. [ABSTRACT FROM AUTHOR]

Microplastics can be ingested by a wide range of aquatic animals. Extensive studies have demonstrated that microplastic ingestion—albeit often not lethal—can affect a range of species life‐history traits. However, it remains unclear how the sublethal effects of microplastics on individual levels scale up to influence ecosystem‐level dynamics through cascading trophic interactions.Here we employ a well‐studied, empirically fed three‐species trophic chain model, which was parameterized to mimic a common type of aquatic ecosystems to examine how microplastic ingestion by fish on an intermediate trophic level can produce cascading effects on the species at both upper and lower trophic levels.We show that gradually increasing microplastics in the ingested substances of planktivorous fish may cause population structure effects such as skewed size distributions (i.e. reduced average body length vs. increased maximal body size), and induce abrupt declines in fish biomass and reproduction.Our model analysis demonstrates that these abrupt changes correspond to an ecosystem‐level tipping point, crossing which difficult‐to‐reverse ecosystem degradation can happen. Importantly, microplastic pollution may interact with other anthropogenic stressors to reduce safe operating space of aquatic ecosystems.Our work contributes to better understanding complex effects of microplastic pollution and anticipating tipping points of aquatic ecosystems in a changing world. It also calls attention to an emerging threat that novel microplastic contaminants may lead to unexpected and abrupt degradation of aquatic ecosystems, and invites systematic studies on the ecosystem‐level consequences of microplastic exposure. [ABSTRACT FROM AUTHOR]

This manuscript investigates the aquaculture practices in the Karaburun region, located in the İzmir Province of Türkiye, known for its natural beauty and marine biodiversity. Focusing on the Karaburun-Ildır Bay Special Environmental Protection Area (SEPA), covering 946.56 km2 of the Aegean Sea, the study evaluates its ecological significance, emphasizing its diverse terrestrial vegetation and rich marine ecosystem. Managed by the Ministry of Environment and Urbanization, the SEPA aims to protect the natural and cultural heritage while promoting sustainable development. In response to global challenges against the decline of wild fish populations, aquaculture emerges as a solution aligned with the principles of blue growth and sustainability. However, aquaculture faces challenges requiring sustainable practices to mitigate environmental and socio-economic impacts. The manuscript delves into aquaculture practices in the Karaburun region, specifically focusing on off-shore mariculture technology and its emphasis on European sea bass and gilthead sea bream production. Through on-site surveys with fish farms in the Karaburun-Ildır Bay SEPA, the study provides a comprehensive analysis of the region's aquaculture industry. The results include the determination of 13 actively engaged companies with a total of 36 licenses, a combined licensed aquaculture production capacity of 49,240 tons/year, and a present production output of 48,470 tons/year. The workforce comprises 486 individuals, including 74 engineers. The region's annual production includes 27,840 tons of sea bass, 14,610 tons of gilt-head bream, 1,820 tons of meagre, and 4,200 tons of tuna. [ABSTRACT FROM AUTHOR]

Soft shoreline engineering is increasingly used to combine shoreline fortification with the enhancement of biodiversity and biological production of land–water transitions. From 2016 to 2021, the large‐scale ecosystem restoration project Marker Wadden has created new multiple wetland islands from local sediments in the highly modified Lake Markermeer, the Netherlands. Instead of replacing steep rip‐rap shorelines with soft shorelines, new islands with soft land–water transitions were engineered to offset the marked declines in bird and fish populations in this Natura 2000 area, protected under the European Union Birds and Habitats Directives.This new approach was evaluated by assessing the added value of the newly created wetland islands with soft shorelines to the existing steep rip‐rap fortified shores of the lake, for the enhancement of fish spawning and nursery habitat.Young‐of‐the‐year fish densities at the Marker Wadden islands were highest in sheltered bays and wetlands with nutrient‐rich silt sediments, and lowest at wind‐exposed sandy beaches. Both newly engineered soft shorelines and existing rip‐rap shorelines contributed to habitat diversity, although fish densities declined considerably with increasing exposure to wind‐induced wave power.Building soft shorelines as a new archipelago instead of replacing existing shoreline habitats increased the total length of the land–water transitions in the lake. The 800 ha Marker Wadden archipelago covers only 1% of the 70,000 ha lake surface area, but provides a 16% increase in shoreline habitat and a fivefold increase in soft shoreline for the lake.We conclude that designing wetland islands as a means of lake restoration can contribute effectively to sheltered habitat enhancement for fish spawning and nurseries, and thereby to the potential conservation of fish communities. The approach of building islands achieves this without compromising the complementary functionality of the original, more mature, shorelines of the lake. [ABSTRACT FROM AUTHOR]

Although fishing is considered the primary cause of the decline in fish populations, increasing evidence of the significant role of climate change has been provided recently in the Mediterranean Sea, which shows one of the highest warming trends in the world. In this area, the most important environmental driver is represented by the increase in seawater temperature. Though several studies have addressed the effects of sea warming on thermophilic species, little attention has been paid to cold-water species. Among these, blue whiting (Micromesistius poutassou) constitutes one of the most important traditional fisheries resources in the northern part of the basin, particularly in the central Adriatic Sea. This area has experienced intense fishing exploitation by the Italian and Croatian fishing fleets. Since 2015, the Pomo/Jabuka Pits area, the fleets’ main fishing ground, has been subject to a series of fishing regulations over time and space. In the present study, we investigated the age structure and growth performance (by means of otoliths) of blue whiting, comparing samples collected during 1985–86 and 2020–21 in the Pomo/Jabuka Pits. Our results show that the 2020–21 blue whiting specimens had a lower length-at-age compared to 1985–86. The asymptotic length estimate decreased from 29 cm TL in 1985–86 to 25 cm TL in 2020–21. The pattern observed might be related to a modification in the cold and dense water formation dynamics in the northern Adriatic Sea, as a consequence of climate change, resulting in higher temperatures and lower nutrient and oxygen exchange, which may have hampered the optimal growth of the species. Moreover, data on the historical trend of landings from the Adriatic Sea reveals a clear decline in catches starting from 2000 onwards. Although the introduction of a fishing ban in the Pomo/Jabuka Pits was an important milestone, the abundance of this species in the area remains at low levels, highlighting a potentially alarming situation for the stock of blue whiting in the central Adriatic Sea. [ABSTRACT FROM AUTHOR]

The Beibu Gulf in China is situated in the tropics, in the western Pacific Ocean. It is an emblematic region combining proximity to a marine biodiversity hotspot and a major seafood hub. Intensification of marine fishing and ocean warming led to a drastic decline in fish populations in the Beibu Gulf during the last decades. This situation urges the development of molecular resources of the Beibu Gulf fish fauna in order to enable automated molecular identifications at the species level for next‐generation monitoring. With this objective, we present the results of a large‐scale campaign to DNA barcode fishes of the Beibu Gulf. We successfully generated 789 new DNA barcodes corresponding to 263 species which, together with 291 sequences mined from Genbank and BOLD, resulted in a reference library of 1080 sequences from 285 species. Based on the use of four DNA‐based species delimitation methods (BIN, ASAP, mPTP, mGMYC), a total of 285 Molecular Operational Taxonomical Units (MOTUs). A single case of cryptic diversity was detected in Scomberomorus guttatus and a single species pair was not captured by delimitation methods. Intraspecific K2P genetic distances averaged 0.36% among sequences within species, whereas K2P genetic distances among species within genera averaged 6.96%. The most speciose families in open water trawling differ from those at fish market, and discrepancies with historical data are discussed in the light of recently documented stock collapses. [ABSTRACT FROM AUTHOR]

The aquaculture industry is growing quickly due to increased fish consumption and a decline in wild fish catch. About half of the world's seafood demand for human consumption is now met by farmed seafood. The aquafeed market is expanding along with the aquaculture sector. Some of the elements in shrimp feed are derived from terrestrial plants and low-value forage fishes (fish meal). It is impossible to produce more fish meals since doing so would harm the ocean's environment and sustainability. The reduction in shrimp feed cost can also be done by introducing low-cost, environment-friendly ingredients in shrimp feed formulation. Therefore, new and ecologically friendly shrimp (Litopenaeus vannamei) feed component sources must be created. Live food organisms are a preferable option for this since they provide a variety of essential amino acids and beneficial triglyce rides like fat, vitamins, and colors in their cell metabolites. Microalgae biomasses also represent feasible ingredients for shrimp feed sources. Their distinctive variety of bioactive chemicals can enhance color and pellet quality, act as a bulk element in shri mp feed, and boost the viability of farmed species. Live food organisms have a great economic potential since they have the highest biomass productivity of all photosynthetic organisms. In addition to giving farmers and exporters a better choice for feeding their fish, the availability of on-grown live food would also open up the prospect of improving the performance and quality of the fish and shrimp through bioencapsulation. This review study examines the possibility of generating natural food biomass as a component in shrimp feed. [ABSTRACT FROM AUTHOR]

Objective: To examine trends in the intake of key food groups among Iranian adults between 2005 and 2016, overall, and according to sociodemographic characteristics. Design: Repeat cross-sectional data from the Iran-STEPwise approach to risk factor surveillance (Iran-WHO STEPS) 2005–2016 were analysed. Regression analyses were used to evaluate trends in the frequency of fruits, vegetables and fish intake and type of oil used over time. Interactions by sex, age and area of residence were examined. Setting: Iran. Participants: 225 221 Iranian adults. Results: The frequency of vegetables (β : −0·03; 95 % CI (−0·06, −0·00); P -trend = 0·030) and fish (β : −0·09; 95 % CI (−0·10, −0·08); P -trend < 0·001) intake and use of solid fat (OR: 0·70; 95 % CI (0·70, 0·72); P -trend < 0·001) declined, whilst the frequency of fruit intake (β -Coeff: 0·03, 95 % CI (0·01, 0·05); P -trend = 0·014) and liquid oil use (OR: 1·40; 95 % CI (1·3, 1·4); P -trend<0·001) rose. Rising trends in fruit intake were larger in mid-aged (40–60 years) and older (>60 years) adults (P -interaction < 0·001), whilst declines in vegetable (P -interaction < 0·001) and fish intake (P -interaction = 0·001) were larger in older adults. The declining use of solid fat was strongest in middle-aged and older adults (P -interaction = 0·035), while the increasing use of liquid oil was strongest in rural areas (P -interaction = 0·011). Conclusions: During the nutrition transition, liquid oil use and the frequency of fruit intake rose, while the frequency of vegetables and fish intake declined. Nonetheless, the fatty acid composition and cooking methods are important considerations. The changes observed are concerning from a public health perspective and demonstrate the need for interventions and possible targets for tailored strategies. [ABSTRACT FROM AUTHOR]

Ethiopia's largest freshwater lake, Lake Tana, is home to 21 endemic fish species, the majority of which are cyprinids in the genus Labeobarbus. The lake is undergoing numerous ecological changes, including an invasion of water hyacinth (Eichhornia crassipes (Mart.) Solms (WH). The aim of this study was to predict the future fish productivity in Lake Tana by considering the increasing water hyacinth infestation. This was accomplished by analyzing a 12-year fishery-independent time-series data set of Labeobarbus, collected from sites infested and not infested by water hyacinth. The stationarity of the data was investigated using the Augmented Dickey-Fuller (ADF) unit root test. First-order data differencing was applied to solve the non-stationarity data to stationarity. With the same standardized fishing gillnet and the same sites, the CPUE during the dry season decreased from 3,502 grams (3.5 kg/day) in 2010 to 360 grams (0.36 kg) in 2020 at the water hyacinth-infested sites, demonstrating a 90% decrease in the daily catch. A reduction in catch per unit effort (CPUE) is evident at the WH sites in all seasons, and the rate of fall in there was faster than at the non-infested site. Box Jenkin's auto-regressive integrated moving average models (ARIMA) modelling predicted that Labeobarbus CPUE will decline by a threefold % by 2032 compared to the current catch. Based on these results, the most suitable model for all the seasons and areas was confirmed to be ARIMA (0, 1, 0) using the lowest value of Akaike Information Criteria (AIC's). The fish production declines with expanding WH infestation will necessitate integrated water hyacinth reduction strategies, closed area and closed spawning seasons, and mesh size regulations to conserve and utilize the resource sustainably. As Labeobarbus is the only examined species in this study, forecasts should be made for other commercially significant fish species in the Lake, such as Oreochromis niloticus and Clarias gariepinus. [ABSTRACT FROM AUTHOR]