Ecosystem dynamics and hypoxia control in the East China Sea: A bottom-up and top-down perspective.

Decades of overfishing have greatly altered the community structure in the East China Sea (ECS). The decrease of top predators in the food web has weakened the control exerted from higher trophic levels. As a result, the biomass of benthic crustaceans, representing the third trophic level, has increased. This has probably led to a restriction of the second trophic level, diminishing its ability to control primary producer biomass. Consequently, the ecological pyramid of trophic levels in the ECS has been altered, reducing the top-down control on the first trophic level. This has made algal blooms more susceptible to occur under nutrient loads, temperate temperatures, and light availability. The reduced abundance of the fourth trophic levels has caused a larger portion of primary productivity to sink directly to the benthic community, bypassing the food web. This influx of sinking organic matter has resulted in organic enrichment in the bottom waters, impacting the biomass and diversity of benthic organisms. Furthermore, it has intensified anthropogenic carbon storage in the sediment. Subsequently, intense decomposition processes occur, leading to the development of anoxia and even hypoxia. The seasonal hypoxia off the Changjiang Estuary can be attributed to the combined influence of top-down control and bottom-up control related to nutrient loading, and terrestrial inputs. In order to mitigate extreme hypoxia events, it is necessary to implement comprehensive fisheries policies that prioritize the maintenance of a healthy and functional ecosystem. This approach should go beyond relying solely on watershed management strategies to regulate riverine inputs. PLAIN LANGUAGE SUMMARY: Decades of overfishing changed the food web in the East China Sea and weaken the resistance of ecosystem to hypoxia. Commercial fishing on top predators decreases the fourth trophic level while relatively increases the third trophic represented by crab and shrimp, which enhances grazing on the zooplankton. The decrease of the second trophic level fails to control the biomass of phytoplankton, thus more primary productivities directly sink to the benthic community and cause organic enrichment. The elevated flux of organic matters to the bottom waters causes the thrive of the carbs and shrimps, as well as more remineralization processes and eventually low oxygen level. Unlike the bottom-up perspective of hypoxia mechanism off the Changjiang Estuary, which is from the nutrient load, phytoplankton bloom, quick sink, effective decomposition and eventually hypoxia, the top-down control focuses on the changes of ecosystem structure and thus derived hindered energy transfer, changed community structure, enhanced carbon sink, elevated remineralization and ultimately hypoxia. These two mechanisms combine with each other and control the seasonal hypoxia off the Changjiang Estuary and even other coastal regions around the world.

How can the rule of law under the WTO framework ensure sustainable fishery governance through fishery subsidies? A study from the perspective of special and differential treatment.

Background: Considering the declining situation of sustainability in global marine fisheries, World Trade Organization (WTO) members successfully concluded the Agreement on Fisheries Subsidies(AFS) after 21 years of negotiations in 2022. As an the integral part of these negotiations, special and differential treatment (SDT) provisions provide developing countries with special rights and developed countries with the possibility to treat developing countries more favorably than other WTO members. Objective: This study analyzed the role of SDT for fisheries subsidies in ensuring sustainable fishery governance by the rule of law, as well as the reflection of SDT under the AFS, to explore whether SDT can support sustainable fishery governance under the WTO framework. Methods: This study is primarily based on official data and critical legal studies and used normative analysis and historical analysis to expose the essence of the SDT issue in the AFS as a political game in the legal form. Results: The practical challenges in the implementation of SDT may affect the compliance willingness of member states. To overcome the obstacles, such as ambiguity and inefficiency, that impede the legalization process of sustainable global marine fishery governance, it is necessary to emphasize the value of SDT for the common interests of the WTO members in marine fisheries legislation. This will benefit the developing countries, especially the small island developing states, in the short term; and the common interests of developed and developing countries in the long term. Policy implications: SDT facilitated the consensus between the developing and developed countries on issues such as illegal, unreported, and unregulated fishing subsidies and overfishing subsidies. However, current SDT practices have deviated from the original intention of the fairness and democratic approach of global marine fisheries governance, which should take into consideration the specific situation of developing countries.

Skinny dolphins: Can poor body condition explain population decline in Indo-Pacific humpback dolphins (Sousa chinensis)?

Indo-Pacific humpback dolphins (IPHDs) who form resident populations along the Chinese coastline are facing a wide range of anthropogenic disturbances including intense fishing and some populations have been shown to experience a severe decline. Body condition is thought to be a good indicator of health since it is linked to survival and reproductive success. In order to better understand population trends, we investigated whether the body condition of IPHDs is poorer in populations whose status is alarming than in other populations. UAV flights were conducted from 2022 to 2023 in four locations (i.e., Sanniang Bay, Leizhou Bay, Jiangmen, and Lingding Bay) in the northern South China Sea. Body ratios were calculated using the body length and widths of IPHDs and were used to analyze differences among seasons, locations, and demographic parameters. A PCA was then used to obtain a detailed picture of the body condition composition of dolphins at each location. Results showed that dolphins from Leizhou Bay and Jiangmen were in better body condition than those from Sanniang Bay and Lingding Bay. Since populations inhabiting Sanniang Bay and Lingding Bay have been shown to experience a sharp decline, it can be hypothesized that poor body condition may have played a role in such a trend. Further investigations of the factors impacting IPHDs' body condition are needed, including monitoring of prey density, contaminant concentration, stress levels, and impacts of human activities on dolphins' behavior. In addition, the creation of a robust scoring method would allow for regular monitoring of IPHDs' body condition to inform conservation measures.

Long-term trends in juvenile Mugil liza abundance in relation to selected environmental and fisheries influences in southern Brazil.

Overfishing constitutes a major threat affecting marine fish population worldwide, including mullet species that have been exploited by fisheries during the reproductive migration in temperate and tropical latitudes for millennia. In the present study, we investigated the relationship of fishing intensity of mullet Mugil liza during its reproductive migration and the abundance of their juveniles in an essential nursery ground for the species in the southwest Atlantic Ocean. To carry out this analysis, we used a 23-year standardized long-term time series (1997-2019) of monthly abundance of M. liza juveniles, local/regional (water temperature, salinity, water transparency and river discharge) and global (ENSO) environmental factors, along with compilations of fishing landing data for the species. Generalized Additive Models (GAM) revealed the negative effect of fishing adult populations on the abundance of juveniles when they reach the marine surf-zone and after recruiting into the estuary. Our results reinforce the importance of adequate conservation and fishery regulation policies to prevent the species' stock from collapsing.

The biology and ecology of the Pacific sharpnose shark Rhizoprionodon longurio.

Amidst global declines in elasmobranch populations resulting predominantly from overfishing, the need to gather data regarding shark ecology is greater than ever. Many species remain data deficient or at risk of going extinct before sufficient conservation measures can be applied. In this review, we summarise existing knowledge regarding the biology and ecology of the Pacific sharpnose shark Rhizoprionodon longurio (Jordan & Hilbert, 1882), a small-bodied carcharhinid shark found in coastal waters of the Eastern Tropical Pacific Ocean that is of both commercial and ecological importance. We compare ecological parameters of this species with its closest extant relatives and identify major knowledge gaps and avenues for future research. In particular, additional studies investigating the behavioural and sensory ecology, as well as potential migratory patterns of the species are needed. Such studies will not only improve our understanding of R. longurio, but provide insight into the extent to which the numerous studies performed on a close relative-Rhizoprionodon terraenovae-provide an accurate representation of the biology and ecology of Rhizoprionodon and carcharhinids more generally.

Composition and Long-Term Variation Characteristics of Coral Reef Fish Species in Yongle Atoll, Xisha Islands, China.

Yongle Atoll was the largest atoll in the Xisha Islands of the South China Sea, and it was a coral reef ecosystem with important ecological and economic values. In order to better protect and manage the coral reef fish resources in Yongle Atoll, we analyzed field survey data from artisanal fishery, catches, and underwater video from 2020 to 2022 and combined historical research to explore the changes in fish species composition and community structure in Yongle Atoll over the past 50 years. The results showed that a total of 336 species of fish were found on Yongle Atoll, belonging to 17 orders and 60 families. Among them, Perciformes had the most fish species with 259 species accounting for 77.08% of the total number of species. The number of fish species in the coral reef of Yongle Atoll was exponentially correlated with its corresponding maximum length and significantly decreases with its increase. The fish community structure of Yongle Atoll changed, and the proportion of large carnivorous fish decreased significantly, while the proportion of small-sized and medium-sized fish increased. At the same time, Yongle Atoll has 18 species of fish listed on the IUCN Red List, 15 of which are large fish. The average taxonomic distinctness (Delta+, Δ+) and the variation taxonomic distinctness (Lambda+, Λ+) in 2020-2022 were lower than the historical data, and the number of fish orders, families, and genera in Yongle Atoll has decreased significantly, which indicates that the current coral reef fish species in Yongle Atoll have closer relatives and higher fish species uniformity. In addition, the similarity of fish species in Yongle Atoll was relatively low at various time periods, further proving that the fish community structure has undergone significant variation. In general, due to multiple impacts, such as overfishing, fishing methods, environmental changes, and habitat degradation, the fish species composition of Yongle Atoll may have basically evolved from carnivorous to herbivorous, from large fish to small fish, and from complexity to simplicity, leaving Yongle Atoll in an unstable state. Therefore, we need to strengthen the continuous monitoring of the coral reef ecosystem in Yongle Atoll to achieve the protection and restoration of its ecological environment and fishery resources, as well as sustainable utilization and management.

eDNA testing reveals surprising findings on fish population dynamics in Thailand.

COVID-19, a global health concern, has an effect on all aspects of the economy. The aquaculture and fishing industries were severely harmed as a result of the closures in multiple nations. Regular systems for inventory monitoring, production, and supply were disrupted. Cancellation of programmes for research, fieldwork, sampling, and tagging influences management-required data. For effective species management, fish dispersion assessments are indispensable. However, due to the difficulty of accessing sampling sites and the associated costs, there is frequently a lack of comprehensive information regarding the distribution and abundance of organisms. The COVID-19 prohibition made fish monitoring more problematic. Due to constant pressure, populations of the stone lapping minnow (Garra cambodgiensis), one of Thailand's overfished fish, are rapidly declining. Therefore, eDNA-based monitoring was devised and implemented to reveal the likely dispersal of the species in Thailand prior to and following the lockdown. At 28 locations within the Chao Phraya River Basin, water samples were collected. qPCR was used to determine the presence or absence of G. cambodgiensis in water samples. In 78 of 252 water samples, a wide range of computed copy numbers for G. cambodgiensis eDNA was observed. It was discovered that samples collected in 2021 (after the lockdown) contain a higher concentration of G. cambodgiensis eDNA than samples collected in 2018 or 2019 (prior to the lockdown). The closure appears to be a boon and may result in a substantial restocking of the fish we have studied. Overall, eDNA-based analysis is an extremely promising new survey instrument.

Historic trophic decline in New England's coastal marine ecosystem.

Overfishing is a worldwide occurrence that simplifies marine food webs, changes trophic patterns, and alters community structure, affecting not only the density of harvested species but also their trophic function. The northwestern Atlantic has a history of heavy fishing, and over the past century has also experienced destructive bottom fishing and harmful mobile fishing gear. After confirming that preservation solvent did not alter the nitrogen stable isotopes of preserved samples, we used museum specimens and modern samples to analyze nitrogen stable isotopes in tissues of two common demersal fishes pre-1950 (1850 to 1950) compared to 2021 to assess changes in trophic positions of coastal New England consumers over this time period. Both the mesopredator Centropristis striata (black sea bass) and the benthivore Stenotomus chrysops (scup) experienced significant declines in trophic position during this time. C. striata declined almost a full trophic level, S. chrysops declined half a trophic level, and these species are now occupying almost the same trophic position. Heavy fishing activities potentially shorten food chains, simplify trophic complexity, lessen the separation of trophic niches, and generally flatten food webs. The consequences of these within-species shifts are poorly investigated but could generate underappreciated cascading impacts on community structure and function. Archived natural-history collections are an invaluable resource for investigating ecological changes in natural communities through time. The evaluation of changing trophic positions via stable isotope analysis may allow fisheries managers to quantify large-scale effects of fishing on ecosystems and food webs over time.

Management strategy of the naked carp (Gymnocypris przewalskii) in the Qinghai lake using matrix population modeling.

Naked carp (Gymnocypris przewalskii) is the only fish species commercially harvested in Qinghai Lake, which is the largest inland saltwater lake in China. Multiple ecological stresses such as long-term overfishing, drying-up of riverine inflows, and decreases in spawning habitat caused the naked carp population to decrease from 320,000 tons before the 1950s to only 3000 tons by the early 2000s. We used matrix projection population modeling to quantitatively simulate the dynamics of the naked carp population from the 1950s to the 2020s. Five versions of the matrix model were developed from the field and laboratory information that represented different population states (high but declining, low abundance, very low abundance, initial recovery, pristine). Equilibrium analysis was applied to density-independent versions of the matrices and population growth rate, age composition, and elasticities were compared among versions. Stochastic, density-dependent version of the most recent decade (recovering) version was used to simulate the time-dependent responses to a range of levels of artificial reproduction (addition of age-1 from hatchery) and of the pristine version to simulate combinations of fishing rate and minimum age of harvest. Results showed the major role of overfishing in the population decline and that the population growth rate was most sensitive to the survival of juveniles and the spawning success of early-age adults. Dynamic simulations showed a rapid population response to artificial reproduction when population abundance was low and that if artificial reproduction continues at its current level, then population biomass would reach 75% of its pristine biomass after 50 years. Simulations with the pristine version identified sustainable fishing levels and the importance of protecting the first few ages of maturity. Overall, modeling results showed that artificial reproduction under conditions of no fishing is an effective approach to restoring the naked carp population. Further effectiveness should consider maximizing survival in the months just after release and maintaining genetic and phenotypic diversity. More information on density-dependent growth, survival, and reproduction, as well as on the genetic diversity and growth and migratory behavior (phenotypic variation) of released and native-spawned fish, would help inform management and conservation strategies and practices going forward.

Conservation successes and challenges for wide-ranging sharks and rays.

Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks. We took advantage of the spatial and temporal gradients in fishing exposure and fisheries management in the Western Atlantic to analyze the effect on the Red List status of all 26 wide-ranging coastal sharks and rays. We show that extinction risk was greater where fishing pressure was higher, but this was offset by the strength of management engagement (indicated by strength of National and Regional Plan of Action for sharks and rays). The regional Red List Index (which tracks changes in extinction risk through time) declined in all regions until the 1980s but then improved in the North and Central Atlantic such that the average extinction risk is currently half that in the Southwest. Many sharks and rays are wide ranging, and successful fisheries management in one country can be undone by poorly regulated or unregulated fishing elsewhere. Our study underscores that well-enforced, science-based management of carefully monitored fisheries can achieve conservation success, even for slow-growing species.

The Serra Spanish mackerel fishery (Scomberomorus brasiliensis - Teleostei) in Southern Brazil: the growing landings of a high trophic level resource / A pesca da cavala, Scomberomorus brasiliensis (Teleostei), no sul do Brasil: o aumento nos desembarques de um recurso de alto nível trófico

Abstract In fisheries, the phenomenon known as fishing down food webs is supposed to be a consequence of overfishing, which would be reflected in a reduction in the trophic level of landings. In such scenarios, the resilience of carnivorous, top predator species is particularly affected, making these resources the first to be depleted. The Serra Spanish mackerel, Scomberomorus brasiliensis, exemplifies a predator resource historically targeted by artisanal fisheries on the Brazilian coast. The present work analyzes landings in three periods within a 50-year timescale on the Parana coast, Southern Brazil, aiming to evaluate whether historical production has supposedly declined. Simultaneously, the diet was analyzed to confirm carnivorous habits and evaluate the trophic level in this region. Surprisingly, the results show that from the 1970's to 2019 Serra Spanish mackerel production grew relatively to other resources, as well as in individual values. The trophic level was calculated as 4.238, similar to other Scomberomorus species, consisting of a case where landings increase over time, despite the high trophic level and large body size of the resource. The results agree with a recent global assessment that has demystified a necessary correlation between high trophic level and overexploitation, but possible factors acting on the present findings are discussed.

Resumo Na pesca, o fenômeno fishing down food webs, ou 'pescando teias tróficas abaixo', expressa a redução do nível trófico na composição das capturas, e tem origem tradicionalmente atribuída à sobrepesca. Sob intenso extrativismo, a resiliência das espécies carnívoras, predadoras de topo, é particularmente afetada, sendo seus estoques os primeiros a entrarem em depleção. A cavala, ou serra, ou sororoca, Scomberomorus brasiliensis, é exemplo de recurso predador historicamente alvo da pesca artesanal, de pequena escala, na costa brasileira. O presente trabalho analisa os valores de desembarque do recurso em três períodos ao longo de 50 anos na costa paranaense, sul do Brasil, com objetivo de avaliar se sua produção tem efetivamente diminuído. Ainda, estuda-se a dieta da espécie na região, para confirmar seus hábitos carnívoros e avaliar o nível trófico na região. Os resultados mostram que, surpreendentemente, dos anos 1970 para 2019 a produção de S. brasiliensis tem aumentado em valores absolutos, bem como relativamente à de outros recursos, em que pese o nível trófico 4,238, similar a outras espécies do gênero. Constata-se que a pesca da cavala na região de estudo constitui um caso de aumento nos desembarques a despeito de elevado nível trófico e grande tamanho corpóreo. Os resultados concordam com recente levantamento em nível mundial, que nega existir correlação necessária entre sobrepesca e nível trófico alto, mas fatores que podem explicar os resultados do presente trabalho são discutidos.

The Serra Spanish mackerel fishery (Scomberomorus brasiliensis – Teleostei) in Southern Brazil: the growing landings of a high trophic level resource / A pesca da cavala, Scomberomorus brasiliensis (Teleostei), no sul do Brasil: o aumento nos desembarques de um recurso de alto nível trófico

In fisheries, the phenomenon known as fishing down food webs is supposed to be a consequence of overfishing, which would be reflected in a reduction in the trophic level of landings. In such scenarios, the resilience of carnivorous, top predator species is particularly affected, making these resources the first to be depleted. The Serra Spanish mackerel, Scomberomorus brasiliensis, exemplifies a predator resource historically targeted by artisanal fisheries on the Brazilian coast. The present work analyzes landings in three periods within a 50-year timescale on the Parana coast, Southern Brazil, aiming to evaluate whether historical production has supposedly declined. Simultaneously, the diet was analyzed to confirm carnivorous habits and evaluate the trophic level in this region. Surprisingly, the results show that from the 1970's to 2019 Serra Spanish mackerel production grew relatively to other resources, as well as in individual values. The trophic level was calculated as 4.238, similar to other Scomberomorus species, consisting of a case where landings increase over time, despite the high trophic level and large body size of the resource. The results agree with a recent global assessment that has demystified a necessary correlation between high trophic level and overexploitation, but possible factors acting on the present findings are discussed.

Na pesca, o fenômeno fishing down food webs, ou 'pescando teias tróficas abaixo', expressa a redução do nível trófico na composição das capturas, e tem origem tradicionalmente atribuída à sobrepesca. Sob intenso extrativismo, a resiliência das espécies carnívoras, predadoras de topo, é particularmente afetada, sendo seus estoques os primeiros a entrarem em depleção. A cavala, ou serra, ou sororoca, Scomberomorus brasiliensis, é exemplo de recurso predador historicamente alvo da pesca artesanal, de pequena escala, na costa brasileira. O presente trabalho analisa os valores de desembarque do recurso em três períodos ao longo de 50 anos na costa paranaense, sul do Brasil, com objetivo de avaliar se sua produção tem efetivamente diminuído. Ainda, estuda-se a dieta da espécie na região, para confirmar seus hábitos carnívoros e avaliar o nível trófico na região. Os resultados mostram que, surpreendentemente, dos anos 1970 para 2019 a produção de S. brasiliensis tem aumentado em valores absolutos, bem como relativamente à de outros recursos, em que pese o nível trófico 4,238, similar a outras espécies do gênero. Constata-se que a pesca da cavala na região de estudo constitui um caso de aumento nos desembarques a despeito de elevado nível trófico e grande tamanho corpóreo. Os resultados concordam com recente levantamento em nível mundial, que nega existir correlação necessária entre sobrepesca e nível trófico alto, mas fatores que podem explicar os resultados do presente trabalho são discutidos.

The Serra Spanish mackerel fishery (Scomberomorus brasiliensis Teleostei) in Southern Brazil: the growing landings of a high trophic level resource

Abstract In fisheries, the phenomenon known as fishing down food webs is supposed to be a consequence of overfishing, which would be reflected in a reduction in the trophic level of landings. In such scenarios, the resilience of carnivorous, top predator species is particularly affected, making these resources the first to be depleted. The Serra Spanish mackerel, Scomberomorus brasiliensis, exemplifies a predator resource historically targeted by artisanal fisheries on the Brazilian coast. The present work analyzes landings in three periods within a 50-year timescale on the Parana coast, Southern Brazil, aiming to evaluate whether historical production has supposedly declined. Simultaneously, the diet was analyzed to confirm carnivorous habits and evaluate the trophic level in this region. Surprisingly, the results show that from the 1970s to 2019 Serra Spanish mackerel production grew relatively to other resources, as well as in individual values. The trophic level was calculated as 4.238, similar to other Scomberomorus species, consisting of a case where landings increase over time, despite the high trophic level and large body size of the resource. The results agree with a recent global assessment that has demystified a necessary correlation between high trophic level and overexploitation, but possible factors acting on the present findings are discussed.

Resumo Na pesca, o fenômeno fishing down food webs, ou pescando teias tróficas abaixo, expressa a redução do nível trófico na composição das capturas, e tem origem tradicionalmente atribuída à sobrepesca. Sob intenso extrativismo, a resiliência das espécies carnívoras, predadoras de topo, é particularmente afetada, sendo seus estoques os primeiros a entrarem em depleção. A cavala, ou serra, ou sororoca, Scomberomorus brasiliensis, é exemplo de recurso predador historicamente alvo da pesca artesanal, de pequena escala, na costa brasileira. O presente trabalho analisa os valores de desembarque do recurso em três períodos ao longo de 50 anos na costa paranaense, sul do Brasil, com objetivo de avaliar se sua produção tem efetivamente diminuído. Ainda, estuda-se a dieta da espécie na região, para confirmar seus hábitos carnívoros e avaliar o nível trófico na região. Os resultados mostram que, surpreendentemente, dos anos 1970 para 2019 a produção de S. brasiliensis tem aumentado em valores absolutos, bem como relativamente à de outros recursos, em que pese o nível trófico 4,238, similar a outras espécies do gênero. Constata-se que a pesca da cavala na região de estudo constitui um caso de aumento nos desembarques a despeito de elevado nível trófico e grande tamanho corpóreo. Os resultados concordam com recente levantamento em nível mundial, que nega existir correlação necessária entre sobrepesca e nível trófico alto, mas fatores que podem explicar os resultados do presente trabalho são discutidos.

Analysis of the available funds supporting marine activities in some key European Mediterranean countries.

The study presented in this article analyzed qualitative and quantitative data on the performance of the European Maritime and Fisheries Fund (EMFF) based on the information reported in the European Union (EU) List of Operations updated to December 2020. Each EMFF measure and type of financial support were divided into three broad categories of subsidies according to their main objectives and scope: capacity enhancing, beneficial, or ambiguous. Capacity enhancing is defined as funds that could incentive overcapacity or overfishing. Beneficial refers to subsidies that have a positive impact on fish stocks and the environment. Ambiguous subsidies correspond to funds that may lead to positive or negative impacts on the environment depending on how they are designed and implemented. The assessment revealed the asymmetric distribution of EMFF resources in the Mediterranean region. In the six member states investigated, EMFF support is concentrated on a limited number of more easily accessible measures from an administrative and financial point of view. Most of the allocated funds are classified as capacity enhancing; other frequently used measures are in the ambiguous category. Small-scale vessels using static gear and accounting for the largest part of the Mediterranean fleets received a negligible share of specific funds for promoting environmentally sustainable fisheries. Most investments are concentrated on larger trawlers to support the temporary cessation of fishing activities and scrapping operations. Further qualitative analysis based on the findings and recommendations of previous reports evaluating the use of EMFF as well as interviews with beneficiaries highlighted that complex administrative procedures and legal uncertainty in the interpretations of some articles of the EMFF regulations are the main reasons for the asymmetric performance of the EMFF measures. The dispersion of responsibilities among European, national and regional authorities, and an evident lack of coordination among them are the main shortcomings that were identified. The limited use of advance payments, the lack of capacity, and technical assistance and obstacles to accessing financial instruments have penalized most of the projects that are focused on innovation, diversification, and environmental sustainability.

Climate-induced habitat suitability changes intensify fishing impacts on the life history of large yellow croaker (Larimichthys crocea).

Intense fishing pressure and climate change are major threats to the fish population and coastal fisheries. Larimichthys crocea (large yellow croaker) is a long-lived fish, which performs seasonal migrations from its spawning and nursery grounds along the coast of the East China Sea (ECS) to overwintering grounds offshore. This study used length-based analysis and habitat suitability index (HSI) model to evaluate the current life-history parameters and overwintering habitat suitability of L. crocea, respectively. We compared recent (2019) and historical (1971-1982) life-history parameters and overwintering HSI to analyze the fishing pressure and climate change effects on the overall population and overwintering phase of L. crocea. The length-based analysis indicated serious overfishing of L. crocea, characterized by reduced catch, size truncation, constrained distribution, and advanced maturation causing a recruitment bottleneck. The overwintering HSI modeling results indicated that climate change has led to decreased sea surface temperature during L. crocea overwintering phase over the last half-century, which in turn led to area decrease and an offshore-oriented shifting of optimal overwintering habitat of L. crocea. The fishing-caused size truncation may have constrained the migratory ability, and distribution of L. crocea subsequently led to the mismatch of the optimal overwintering habitat against climate change background, namely habitat bottleneck. Hence, while heavy fishing was the major cause of L. crocea collapse, climate-induced overwintering habitat suitability may have intensified the fishery collapse of L. crocea population. It is important for management to consider both overfishing and climate change issues when developing stock enhancement activities and policy regulations, particularly for migratory long-lived fish that share a similar life history to L. crocea. Combined with China's current restocking and stock enhancement initiatives, we propose recommendations for the future restocking of L. crocea in China.

A review of the knowledge of reef fish in the Southwest Atlantic.

Reef environments are rapidly transforming worldwide, and these changes are causing major impacts to the reef ecosystem. Scientific knowledge is strategic for marine conservation and management in these scenarios. Aiming to contribute to this subject, a systematic review from 1967 to 2020 was conducted, in order to identify gaps in studies regarding reef fish species, ecosystem components and processes. Multidisciplinary sciences concerning reef fish have been rising, mainly in the fields of basic biology and ecology. Besides that, phase shifts and ecosystem services were absent terms in the analyzes of co-occurrence. Research in the ethnosciences needs to be increased, and will improve access to local ecological knowledge, which can be used as a tool to address issues in reef environments. Socio-ecological systems are components of this landscape that has had few publications. The participation in the elaboration of public policies can be a new avenue to foster the biodiversity of reef environments.

Managing fisheries for maximum nutrient yield.

Wild-caught fish are a bioavailable source of nutritious food that, if managed strategically, could enhance diet quality for billions of people. However, optimising nutrient production from the sea has not been a priority, hindering development of nutrition-sensitive policies. With fisheries management increasingly effective at rebuilding stocks and regulating sustainable fishing, we can now begin to integrate nutritional outcomes within existing management frameworks. Here, we develop a conceptual foundation for managing fisheries for multispecies Maximum Nutrient Yield (mMNY). We empirically test our approach using size-based models of North Sea and Baltic Sea fisheries and show that mMNY is predicted by the relative contribution of nutritious species to total catch and their vulnerability to fishing, leading to trade-offs between catch and specific nutrients. Simulated nutrient yield curves suggest that vitamin D, which is deficient in Northern European diets, was underfished at fishing levels that returned maximum catch weights. Analysis of global catch data shows there is scope for nutrient yields from most of the world's marine fisheries to be enhanced through nutrient-sensitive fisheries management. With nutrient composition data now widely available, we expect our mMNY framework to motivate development of nutrient-based reference points in specific contexts, such as data-limited fisheries. Managing for mMNY alongside policies that promote access to fish could help close nutrient gaps for coastal populations, maximising the contribution of wild-caught fish to global food and nutrition security.

How Well Do 'Catch-Only' Assessment Models Capture Catch Time Series Start Years and Default Life History Prior Values? A Preliminary Stock Assessment of the South Atlantic Ocean Blue Shark Using a Catch-Based Model.

CMSY++, an improved version of the CMSY approach developed from Catch-MSY which uses a Bayesian implementation of a modified Schaefer model and can predict stock status and exploitation, was used in the present study. Evaluating relative performance is vital in situations when dealing with fisheries with different catch time series start years and biological prior information. To identify the influences of data inputs on CMSY++ outputs, this paper evaluated the use of a nominal reported catch and a reconstructed catch dataset of the South Atlantic blue shark alongside different priors of the blue shark's productivity/resilience (r) coupled with different indices of abundance. Results from the present study showed that different catch time series start years did not have a significant influence on the estimation of the biomass and fishing reference points reported by CMSY++. However, uninformative priors of r affected the output results of the model. The developed model runs with varying and joint abundance indices showed conflicting results, as classification rates in the final year changed with respect to the type of index used. However, the model runs indicated that South Atlantic blue shark stock could be overfished (B2020/Bmsy = 0.623 to 1.15) and that overfishing could be occurring (F2020/Fmsy = 0.818 to 1.78). This result is consistent with the results from a previous assessment using a state-space surplus production model applied for the same stock in 2015. Though some potential could be observed when using CMSY++, the results from this model ought to be taken with caution. Additionally, the continuous development of prior information useful for this model would help strengthen its performance.

SELECTIVIDAD DE RED DE ENMALLE PARA CAPTURA DE BOCACHICO (Prochilodus magdalenae, Prochilodontidae) EN LA CIÉNAGA DE ZÁRATE / Gillnet selectivity for catching bocachico (Prochilodus magdalenae, Prochilodontidae) In Zarate Swamp

RESUMEN La estimación precisa de curvas de selectividad de redes de enmalle en una población de peces es un requisito importante para la sostenibilidad de los stocks explotados. Sin embargo, los trabajos de selectividad para artes de pesca que operan en ecosistemas continentales de Colombia son muy escasos. Este estudio determinó los parámetros de selectividad de redes de enmalle utilizadas en la captura del bocachico (Prochilodus magdalenae). El diseño experimental evaluó tres tamaños de malla (5,72; 6,35 y 8,89 cm) y las capturas se realizaron en diferentes sitios de pesca de la ciénaga de Zárate. Con la utilización del método SELECT se estimaron los parámetros de selectividad y mediante un análisis de Kruskall Wallis se determinaron las diferencias en la captura por unidad de esfuerzo. Además, el tamaño de malla óptimo fue calculado a partir del principio de similaridad geométrica de Baranov. Los resultados muestran que el modelo normal con varianza proporcional al tamaño de malla es el que mejor ajuste presentó para la captura de bocachico. Las longitudes modales calculadas con el modelo normal con varianza proporcional al tamaño de malla fueron 22,90, 25,45 y 35,63 cm para tamaños de malla de 5,72, 6,35 y 8,89 cm, respectivamente. El tamaño de malla óptimo calculado fue 6,99 cm. Los resultados indican que las redes con tamaños de malla de 5,72 cm e inferiores tienen un efecto sobre la estructura de tamaños del bocachico. Estas redes requieren ser priorizadas en la formulación de medidas de manejo basadas en la ordenación de este arte de pesca, lo que permitirá la sostenibilidad de la pesquería.

ABSTRACT Accurate estimation of gillnet selectivity curves in a fish population is an important requirement for the sustainability of exploited stocks. However, selectivity studies for fishing gear operating in Colombia's inland ecosystems is very rare. This study determined the gillnet selectivity parameters used in the catch of the bocachico (Prochilodus magdalenae). The experimental design evaluated three mesh sizes (5.72, 6.35 and 8.89 cm) and the catches were made in different fishing sites at the Zárate swamp. With the use of the SELECT method, the selectivity parameters were estimated and the Kruskall Wallis test determined the differences in the catch per unit effort. Furthermore, the optimal mesh size was calculated from Baranov's principle of geometric similarity. The results show that the normal model (scale) presented the best fit for the catch of bocachico. The modal lengths calculated with the normal scale model were 22.90, 25.45, and 35.63 cm for mesh sizes of 5.72, 6.35, and 8.89 cm, respectively. The calculated optimal mesh size was 6.99 cm. The results indicate that nets with mesh sizes of 5.72 cm and lower influences the size structure of the bocachico. These nets need to be prioritized in the formulation of management measures based on the regulation of this fishing gear, which will allow the sustainability of the fishery.

Local Overfishing Patterns Have Regional Effects on Health of Coral, and Economic Transitions Can Promote Its Recovery.

Overfishing has the potential to severely disrupt coral reef ecosystems worldwide, while harvesting at more sustainable levels instead can boost fish yield without damaging reefs. The dispersal abilities of reef species mean that coral reefs form highly connected environments, and the viability of reef fish populations depends on spatially explicit processes such as the spillover effect and unauthorized harvesting inside marine protected areas. However, much of the literature on coral conservation and management has only examined overfishing on a local scale, without considering how different spatial patterns of fishing levels can affect reef health both locally and regionally. Here, we simulate a coupled human-environment model to determine how coral and herbivorous reef fish respond to overfishing across multiple spatial scales. We find that coral and reef fish react in opposite ways to habitat fragmentation driven by overfishing, and that a potential spillover effect from marine protected areas into overfished patches helps coral populations far less than it does reef fish. We also show that ongoing economic transitions from fishing to tourism have the potential to revive fish and coral populations over a relatively short timescale, and that large-scale reef recovery is possible even if these transitions only occur locally. Our results show the importance of considering spatial dynamics in marine conservation efforts and demonstrate the ability of economic factors to cause regime shifts in human-environment systems.