Adaptive Fisheries Management Research Articles

Northeast Atlantic fish stock productivity hindcasts and forecasts from a Bayesian framework reveal pronounced climate‐induced dynamics

AbstractClimate change continues to exert pressure on ocean ecosystems. The fisheries‐related responses, such as altered body growth, recruitment and spatial distribution of the targeted stock(s), have generally been reasonably well investigated. Nevertheless, there are still important knowledge gaps in how biophysical drivers impact stock productivity and thereby sustainable harvest levels. Considering this, we investigated 26 fish stocks in the Northeast Atlantic, a region characterized by accelerated climate change effects and a diverse set of fisheries. A novel, stepwise, Bayesian framework to quantify stock productivity was established to identify shared trends and project future patterns, aiming at determining essential baselines for adaptive fishery management in the face of climate change. Despite variation among large marine ecosystems and stocks, an overall declining trend in productivity over the past four decades was observed, especially in high‐latitude areas. These hindcast results were mainly attributed to higher temperatures posing negative effects on productivity, which was dependent on the stock's thermal preference. Contrastingly, the proxy for food availability – gross secondary production – exhibited less consistent impacts. In the forecast, the applied Shared Socio‐economic Pathways (SSPs) indicated that most stocks are likely to encounter adverse effects, with the worst cases expected to occur under SSP2‐4.5 in the 2050s, and under SSP5‐8.5 in the 2090s. Thus, this study generally not only supports earlier climate vulnerability assessments (‘scorings’) of experts but also provides evidence for revised directional effects under climate change, underlining the complexity of processes affecting stock productivity.

Trophic ecology of the greater amberjack in relation to marine environmental characteristics in Taiwanese waters illustrated by stable isotope and stomach content approach

The greater amberjack (Seriola dumerili) holds significant commercially and ecologically important large pelagic marine species in Taiwanese waters. The aim of this study was investigates its stomach contents and stable isotope signatures (δ13C and δ15N) were used to explore the trophic ecology and to detect the dietary variations by length, sex, and season and their associations with marine environmental characteristics. Utilizing a generalized additive model, we elucidate how marine environmental variables influence greater amberjack feeding habitats. Our findings revealed that the mixed layer depth and sea surface temperature explained the highest influence in the greater amberjack feeding ground. To reveal the trophic ecology of the greater amberjack and their ecosystem trophic dynamics, we used an innovative approach combining stomach content analysis (SCA) and stable isotope analysis (SIA) of carbon and nitrogen (δ13C and δ15N) coupled with Bayesian mixing model analysis. By contrast, some of the results in SIA were different from the most important food items identified in SCA; in general, they prefer to consume pelagic prey species. The Bayesian mixing models indicated that the target predator species diet structure was dominated by Trichiuridae and Leiognathidae prey species, as indicated by the highest δ15N values. The relationships of the greater amberjack weight and length were not significant with δ13C values (p > 0.05) but were significant (p < 0.001) with δ15N values. The relationships between trophic positions (TPs) in terms of length, sex, and season suggested an ontogenetic shift, with varied TP values between 4.01 and 5.18, indicating that the greater amberjack is the top-level predator species in the pelagic marine ecosystem. These findings can guide ecosystem-based adaptive fishery management and conservation because the local prey species depletion and variations in marine environmental conditions may affect greater amberjack fisheries in Taiwanese waters.

Effects of climate change and variability on large pelagic fish in the Northwest Atlantic Ocean: implications for improving climate resilient management for pelagic longline fisheries

Climate change influences marine environmental conditions and is projected to increase future environmental variability. In the North Atlantic, such changes will affect the behavior and spatiotemporal distributions of large pelagic fish species (i.e., tunas, billfishes, and sharks). Generally, studies on these species have focused on specific climate-induced changes in abiotic factors separately (e.g., water temperature) and on the projection of shifts in species abundance and distribution based on these changes. In this review, we consider the latest research on spatiotemporal effects of climate-induced environmental changes to HMS’ life history, ecology, physiology, distribution, and habitat selection, and describe how the complex interplay between climate-induced changes in biotic and abiotic factors, including fishing, drives changes in species productivity and distribution in the Northwest Atlantic. This information is used to provide a baseline for investigating implications for management of pelagic longline fisheries and to identify knowledge gaps in this region. Warmer, less oxygenated waters may result in higher post-release mortality in bycatch species. Changes in climate variability will likely continue to alter the dynamics of oceanographic processes regulating species behavior and distribution, as well as fishery dynamics, creating challenges for fishery management. Stock assessments need to account for climate-induced changes in species abundance through the integration of species-specific responses to climate variability. Climate-induced changes will likely result in misalignment between current spatial and temporal management measures and the spatiotemporal distribution of these species. Finally, changes in species interactions with fisheries will require focused research to develop best practices for adaptive fisheries management and species recovery.

Management strategies can buffer the effect of mass mortality in early life stages of fish

Abstract Mass mortality (MM) events affecting early life stages of fish can have strong and long‐term consequences for population abundance and demography as well as the economic activity supported by exploited stocks. Adaptive fishery management may help mitigate economic impacts and ensure sustainable resource use following a MM event. Using a state‐space life cycle model, we simulated ‘what‐if’ scenarios of MM on Northeast Arctic cod (Gadus morhua) eggs and larvae. We compared the expected catches, total stock biomass (TSB), and interannual variability in catches over a period of 10 years after the simulated disturbance. We further evaluated a range of management mitigation strategies, namely reductions in fishing mortality of varying duration (1–10 years) and intensity (no fishing reduction to full ban). A large range of reductions in fishing led to an increase in expected catches over 10 years compared to no reductions, especially when applied immediately after the perturbation and when the cod population was characterized by a high mean age and high TSB. Severe fishing reductions can increase catches substantially but are associated with high interannual variability. Fishing reductions of moderate intensity applied between 1 and 4 years would allow to increase catches with only a slight increase in interannual variability. Our findings demonstrate the potential benefits of an adaptive approach to fisheries management and highlight that mitigation actions may ensure the sustainable exploitation of fish stocks in the wake of unexpected disturbances. Synthesis and application. Mass mortality events during early life stages of fish can potentially have substantial and long‐term effects on the population. Mitigation is more efficient when the affected population has a diverse age structure and when the mitigation strategy is applied immediately after the perturbation. Severe reduction in fishing mortality is an efficient measure to increase the expected average catch but is associated with high interannual variability. Fishing reduction of moderate intensity applied during 1–4 years after the event also increases the expected average catch with only slightly higher interannual variability in catches.

Disentangling interactions between seagrasses and small-scale fisheries using scientific and local traditional knowledge

Seagrass meadows deliver key ecosystem services in coastal environments worldwide by hosting early and adult life stages of many fish stocks, improving water quality, capturing carbon dioxide (mitigating the effects of global warming), protecting against adverse events and providing leisure opportunities. Shellfishing is often carried out in seagrass meadows, causing alterations derived from harvesting and/or culture processes. While the negative impacts of shellfisheries on seagrass meadows have been well established, the effects of the meadows on shellfishing have not yet been explored. In this study we analyzed the two-way interactions between shellfishing and Zostera spp. beds in north-west Spain and identified gaps in the governance system related to seagrass management. We conducted interviews (with 154 shellfishers) and held workshops (involving 61 shellfishers) to collect and validate information on the perceptions of shellfishers regarding the ecosystem services supplied by seagrass meadows, the interactions with shellfishing activity and how to improve the management of the activity in these key habitats. In general, shellfishers viewed the presence of seagrass negatively because greater physical effort is needed to extract the shellfish from among the plants. The shellfishers also recognized that the plants are easily damaged during their work. Temporal trends were also perceived negatively, as catches have been decreasing over time, while the area occupied by seagrass meadows has increased. However, experienced shellfishers recognized the benefits of the meadows for coastal ecosystems and fisheries (including those that they exploited), such as increased recruitment of the target species, to the extent that they were open to the allocation of areas to seagrass conservation. The compatibility of traditional shellfishing and management of seagrass meadows should be fostered by developing seagrass monitoring programs to develop adaptive fisheries management strategies and ensure conservation of these complex social-ecological systems.

Evaluating adaptive management frameworks for data-limited crustacean fisheries

Crustacean fisheries represent an increasingly important contribution to global landings, food security and economic growth, especially in developing countries. However, many productive and valuable crustacean fisheries in Asian countries are characterized by limited data availability, scientific capacity, and fisheries management. Adaptive management frameworks, which use past and emerging information to provide stock status information and management advice, have been touted as particularly applicable for managing capacity- and data-limited fisheries because they employ methods that can improve data collection and result in evaluations of stock and ecosystem status with varying levels of data and capacity. Here, we examined the application of three adaptive fisheries management frameworks (FISHE, FishPath, and DLMtool) to three typical Asian crustacean fisheries that offered contrasting data types and availability, governance, and management and socio-economic contexts. Our aim was to evaluate their suitability for crustacean fisheries and identify particular data and modeling needs and management gaps in these fisheries. We found that while each of the frameworks could effectively recommend suitable monitoring, assessment, and management options given particular contextual factors, there were also limitations with each approach. For example, FISHE took a more wholistic view of ecosystem and fisheries heath, while the other frameworks were more focused on particular aspects of management such as stock assessment (FishPath) and management strategy evaluation (MSE; DLMtool). Applications of each approach also highlighted particular challenges in collecting commercial catch data due to limited monetary investment and poorly designed monitoring programs, which further hindered the implementation of catch and effort limits. The three frameworks also shared common challenges when applied to crustacean species, mainly associated with misalignment with the unique life-histories of crustaceans compared to finfish. By comparing the outputs of the three frameworks, we highlighted their respective strengths and weaknesses and propose an integrated framework that incorporates elements of each of the three frameworks. This integration offers a more comprehensive adaptive roadmap tailored to crustacean fisheries, which involves a mix of qualitative and quantitative approaches that could be applied depending on contextual factors and capacities. To further improve the applicability of adaptive frameworks to crustacean fisheries, we suggest considering crustacean's unique life history and the effects of climate change and other environmental factors, strengthening participatory processes, and balancing socio-economic and ecological objectives.

Small island nations can achieve food security benefits through climate-adaptive blue food governance by 2050

Small island nations are highly dependent on food from aquatic environments, or blue food, and vulnerable to climate change and global food market price volatility. By 2050, rising populations will demand more food through various protein sources, including from the sea. This study identifies which small island nations can improve food self-sufficiency from the sea by implementing tailored climate-adaptive fisheries governance strategies that adapt to shifting marine resources. We combined projections of seafood demand and local catch under different future scenarios of global carbon emissions and local adaptive fisheries management to estimate potential seafood surpluses or deficits from by 2050 for 31 small island nations worldwide. We find that adapting fisheries management every 10 years could mitigate even worst-case projections of climate change impacts on locally available seafood, building a seafood surplus by 2050 in the Seychelles, Maldives, Cabo Verde, Bahamas, Antigua and Barbuda, Kiribati, PNG, Fiji, FSM, Tuvalu, and Marshall Islands. Strategic financial and capacity investments by the international community could help realize the full potential of food security from the sea for those nations. However, we project deficits in locally caught seafood by 2050 in Comoros, Sao Tome and Principe, Mauritius, Barbados, Dominican Republic, Cuba, Dominica, Jamaica, Grenada, St. Lucia, St. Vincent and the Grenadines, Trinidad and Tobago, Haiti, Palau, Samoa, Nauru, and the Solomon Islands, regardless of adapting fisheries management. For those nations, we recommend international collaboration that strengthens food security from sources other than the sea coupled with investments in locally sustainable aquaculture. Overall, we find that climate-adaptive fisheries management can benefit a range of the studied small island nations, by supporting both food security goals as well as economic goals of productive fisheries for international trade

A delay‐differential model for representing small pelagic fish stock dynamics and its application for assessing alternative management strategies under environmental uncertainty

AbstractWe present a novel adaptation of the classic discrete delay‐difference model, a continuous delay‐differential model (cDDM), which can adequately represent population dynamics of stocks that turn over rapidly and continuously over time (e.g., small pelagic fish, small tunas, and shrimps). We used the Northern‐Central Peruvian anchoveta stock (Engraulis ringens, Engraulidae) as a case study for implementing the cDDM and conducted a management strategy evaluation (MSE) through stochastic optimization in policy space (SOPS). Our results showed that cDDM integrated with SOPS efficiently searches optimum and near‐optimum harvest control rules (HCR) and is an alternative to pre‐setting arbitrary HCRs as in traditional MSE. The cDDM showed comparable stock biomass and recruitment estimate reconstructions to more complex stock assessment models described for anchoveta. We concluded that the anchoveta stock is sustainably managed and is an example of adaptive fisheries management under high ocean‐climate variability and uncertainty. Contrary to fishery textbooks, the anchoveta's collapse was not entirely due to the 1972 El Niño (EN) but a recruitment failure preceding EN. Our reconstructions revealed that low recruitment (or recruitment failure) could still occur at high stock biomass. Anchoveta's stock biomass is larger than pre‐collapse, likely due to favourable environmental conditions (a cooling trend) and management, despite more frequent and stronger EN events. SOPS quickly revealed that harvest strategies with large base biomass (&gt;5 mmt) lead to higher interannual stock variability and would not produce substantial increases in long‐term yield. Alternative HCRs with lower base biomass, while adjusting for productivity regimes, have similar long‐term yields without affecting the long‐term average stock.

Fishers’ Traditional Knowledge: A Primary Requirement for Adaptive Fisheries Management in the Northern Persian Gulf

Fishers’ Traditional Knowledge: A Primary Requirement for Adaptive Fisheries Management in the Northern Persian Gulf

Strengthening small-scale fisheries management and conservation in Myanmar through locally managed marine areas

AbstractThe NGO Fauna &amp; Flora started working in the Myeik Archipelago, southern Myanmar in 2013, and in 2017 three locally managed marine areas were established to aid sustainable fisheries management and support biodiversity conservation. These sites are the first protected areas specifically established for co-management of marine fisheries in Myanmar, in which long-term management rights have been formally granted to local fishing communities. The establishment of a further four locally managed marine areas is now in progress, with ambitions for a network to be established throughout the archipelago. To track changes in these habitats over time, assess effectiveness and inform adaptive fisheries management, annual coral reef monitoring will be conducted at these community-managed sites. We provide an overview of the locally managed marine areas recently established in Myanmar and of proposed new sites, and detail the establishment of the first permanent coral reef monitoring transects. In sharing the initial evidence gathered on the impact of new, local management measures, we aim to highlight the importance and benefit of developing marine resource management systems to strengthen fisheries management while simultaneously establishing a monitoring framework to fill a national and global coral reef data gap.

Climate-induced small pelagic fish blooms in an overexploited marine ecosystem of the South China Sea

Marine ecosystems are a primary conservation concern because of the separate and synergistic effects of overfishing and climate change on their productivity and biodiversity. For the purpose of implementing ecosystem-based fisheries management, it is essential to understand how fish stocks respond to climate change in marine ecosystems, especially those that have been overexploited. The Beibu Gulf in the northwestern part of the South China Sea has long been one of China’s major fishing grounds. After the collapse of the demersal ecosystem in 1990 s, small pelagic fishes, including Japanese jack mackerel (Trachurus japonicus) and Japanese scad (Decapterus maruadsi), have occupied a more-important ecological niche in this gulf. However, insufficient research on how small pelagic fish respond to climate change creates great uncertainty for implementing the current management measures. This study used fish data of trawl surveys and environmental data to investigate possible mechanisms leading to dramatic fluctuations in small pelagic fish populations and their possible effects on the Beibu Gulf marine ecosystem. Abnormal blooms of small pelagic fish, especially T. japonicus and D. maruadsi, occurred following four La Niña events (in 2007/2008, 2010/2011, 2011/2012, and 2020/2021). Moreover, the dominant fish species shifted observably and regularly, Shannon–Wiener diversity and Pielou’s evenness decreased significantly in the northeastern coastal waters of the gulf, and the spatial pattern of the fish community was reorganized in this ecosystem. The small pelagic fish blooms in summers probably resulted from a combination of climate change, overfishing, and a summer fishing moratorium, which thereby caused a series of responses in the marine ecosystem. Fluctuations in the small pelagic fish populations after La Niña events seemed more dramatic after the collapse of demersal fish stocks. Therefore, we emphasize the need for implementing ecosystem-based, preventive, and adaptive fisheries management.

Risks and adaptation options for the Mediterranean fisheries in the face of multiple climate change drivers and impacts

Abstract The Mediterranean Sea is among the most vulnerable semi-enclosed seas to climate change. Multiple oceanic changes occur besides warming that can generate numerous ecological, social, and economic risks, challenging fisheries management at various spatial scales—from local to international. In this study, we applied a semi-quantitative climate risk assessment (CRA) to the Mediterranean small pelagic and demersal fisheries in relation to a diversity of climate-related drivers and impacts. We assessed the risks of climate change effects on demersal and small pelagic fisheries resources, fishing operations, livelihoods, and wider social and economic implications in seven sub-regions of the Mediterranean Sea. Ocean warming, an increase in extreme weather events, and changes in vertical stratification resulted in the most important climate drivers. Overall, climate drivers present higher risks to fishing resources and livelihoods than to fishing operations and wider social and economic impacts. The study puts into evidence geographic differences in terms of the drivers and impacts, with the south-eastern Mediterranean being the sub-region with higher risk levels for both fisheries, while the north-central Mediterranean also showed important risk levels for the demersal fisheries. The study furthermore discusses the most plausible adaptive measures in management, policy, research, and livelihoods to be potentially applied to address high priority risks, as well as various implementation concerns and technical effectiveness issues. Enhancing adaptive fisheries management needs to be the primary strategy for this region to reverse the high number of overfished stocks and build resilience to climate change.

German fishery’s adaptation to historic events, Western Baltic Sea, 1890–1950

Marine social-ecological systems (SES) have been providing important cultural, social, and economic services for many centuries. They are, however, increasingly threatened by fast changing environmental, ecological, and socio-economic conditions. As historical marine research is increasingly developing into a multidisciplinary endeavour, it offers outstanding points of departure to analyse historic events and the response and adaptation of the respective SES. Such knowledge helps to inform today’s fisheries management and promotes successful management of changing ecosystems. Here, we compile and analyse historical data (1890–1950) of the German Western Baltic Sea fishery SES. This period is characterised by a series of strong impacts due to political, technological, economic, and ecological changes, such as two world wars, a global economic crisis, and other economic or ecological disasters. In our opinion, potential negative effects of those events were in the past attenuated by the system’s high capacity to adapt. However, most of the fishers´ historic options on how to respond and adapt have recently become no longer available. New threats (e.g. climate change) have emerged instead. We conclude that today’s fisheries management needs to integrate options of adaptation by exhausting all present or future opportunities. Adaptive fisheries management should not only focus on environmental change but need to include socio-economic change as well.

The Okavango Delta: Fisheries in a fluctuating floodplain system

Wetlands are among the most productive ecosystems globally characterized by dynamic interactions between terrestrial and aquatic habitats at different scales. These systems support valuable floodplain fisheries that are a major livelihood for riparian communities. Understanding the dynamics of these systems is important for developing adaptive fisheries management paradigms that will facilitate access and sustainability to this cheap but high-quality food and nutrition source. The Okavango Delta in Botswana is a large land-locked complex river-floodplain ecosystem, with a diverse biota, and high environmental heterogeneity due to periodic drying and flooding along a space and time gradient. It is characterized by a multi-species, multi-gear fishery adapted to the seasonal flood pulse. The Delta’s fish species assemblage undergoes seasonal changes driven by the flood regime. There is also a dynamic inter-annual variability in the fish species assemblage, particularly between “good” and “bad” flood years. During the wet season, high flows increase connectivity in three dimensions (longitudinal, lateral, and vertical) which facilitates dispersal of aquatic biota, nutrients, and other material among successive locations in the riverscape. However, the dry season results in alteration or reduction in aquatic habitats available for fish reproduction. Similarly, low floods may reduce inputs of nutrient resources from the terrestrial environment that support aquatic food webs and can lead to community disruption, even to the point of local extirpation of stranded fish in fragmented ephemeral pools in the floodplain. Consequently, the periodicity, magnitude and predictability of flows are the major drivers of the systems’ capacity to sustain persistent fisheries production and other ecosystem services affecting human welfare. We argue that identification of the processes that sustain production and biodiversity patterns is an essential step towards a better ecological understanding and natural resource management of river-floodplain systems. Based on this review, we debate that floodplain fisheries, like in the Okavango Delta, should be exploited using a diverse exploitation pattern to ensure a harvesting regime in balance with system productivity. Such balanced fishing pattern, based on traditional fishing practices, facilitates the provision of food and nutritional value of the fishery to marginalized communities.

Ten lessons on the resilience of the EU common fisheries policy towards climate change and fuel efficiency - A call for adaptive, flexible and well-informed fisheries management

To effectively future-proof the management of the European Union fishing fleets we have explored a suite of case studies encompassing the northeast and tropical Atlantic, the Mediterranean, Baltic and Black Seas. This study shows that European Union (EU) fisheries are likely resilient to climate-driven short-term stresses, but may be negatively impacted by long-term trends in climate change. However, fisheries’ long-term stock resilience can be improved (and therefore be more resilient to increasing changes in climate) by adopting robust and adaptive fisheries management, provided such measures are based on sound scientific advice which includes uncertainty. Such management requires regular updates of biological reference points. Such updates will delineate safe biological limits for exploitation, providing both high long-term yields with reduced risk of stock collapse when affected by short-term stresses, and enhanced compliance with advice to avoid higher than intended fishing mortality. However, high resilience of the exploited ecosystem does not necessarily lead to the resilience of the economy of EU fisheries from suffering shocks associated with reduced yields, neither to a reduced carbon footprint if fuel use increases from lower stock abundances. Fuel consumption is impacted by stock development, but also by changes in vessel and gear technologies, as well as fishing techniques. In this respect, energy-efficient fishing technologies already exist within the EU, though implementing them would require improving the uptake of innovations and demonstrating to stakeholders the potential for both reduced fuel costs and increased catch rates. A transition towards reducing fuel consumption and costs would need to be supported by the setup of EU regulatory instruments. Overall, to effectively manage EU fisheries within a changing climate, flexible, adaptive, well-informed and well-enforced management is needed, with incentives provided for innovations and ocean literacy to cope with the changing conditions, while also reducing the dependency of the capture fishing industry on fossil fuels. To support such management, we provide 10 lessons to characterize ‘win-win’ fishing strategies for the European Union, which develop leverages in which fishing effort deployed corresponds to Maximum Sustainable Yield targets and Common Fisheries Policy minimal effects objectives. In these strategies, higher catch is obtained in the long run, less fuel is spent to attain the catch, and the fisheries have a higher resistance and resilience to shock and long-term factors to face climate-induced stresses.

Reproductive cycle of the golden carpet shell (Polititapes aureus) in the Ria Formosa lagoon (southern Portugal)

AbstractThe present study described the gametogenesis and assessed the pattern of energy storage throughout the reproductive cycle of the golden carpet shell (Polititapes aureus) from the Ria Formosa lagoon (southern Portugal). Monthly sampling was performed for two years (March 2016–February 2018) and the study was based on gonad histology, complemented by the estimation of the mean gonadal index, body condition index and biochemical composition. The species’ reproductive cycle presented a seasonal pattern, with a resting period mainly between October and January and gametogenesis beginning around February–March. The spawning season of P. aureus was shorter in 2016 (June–September) than in 2017 (May–October). Furthermore, ripe individuals were very scarce (1.3%) in 2017 compared with the previous year (11.4%). Mean gonadal index (GI) reflected the species’ reproductive cycle and the body condition index (CI) and biochemical composition of the individuals exhibited high variation between years. Regarding the biochemical composition, proteins ranged between 190.6 and 595.2 μg mg−1, glycogen from 5.7 to 102.6 μg mg−1 and total lipids between 31.6 and 80.7 μg mg−1. The reproduction of P. aureus was strongly influenced by fluctuations in both seawater temperature and chlorophyll a, as reflected through the temporal variation in the gonadal cycle, condition index and biochemical composition. Overall, the information gathered in this study is valuable to propose scientifically based harvesting management measures for the long-term sustainable exploitation of this shellfish resource, further reinforcing the importance of implementing adaptive fishery management strategies to cope with global climate change.

Modeling Atlantic sea scallop (Placopecten magellanicus) scope for growth on the Northeast U.S. Shelf

AbstractAtlantic sea scallops support one of the most valuable fisheries in the eastern United States. The scallop population is susceptible to climate‐related environmental stress. Assessing and projecting climate impacts rely on the fundamental understanding of scallop ecophysiology, including the influences of temperature and food supply on its energy balance and growth potential. In this study, we developed a scope for growth (SFG) model driven by high‐resolution hydrodynamic and biological models to assess the spatial and seasonal variability of scallop energy dynamics. The overall SFG on the Northeast U.S. Shelf is higher in May–June and lower in January–February, with substantial spatial heterogeneity. In the Mid‐Atlantic Bight (MAB), negative SFG occurs from July to October due to strong thermal stress. Particulate organic matter in detrital form is an important food source for scallops, with higher/lower contribution in the cold/warm seasons, respectively. Warming and food deficiency induce a noticeable contraction of suitable scallop habitats in the MAB, while their impacts on Georges Bank are insignificant. Known seasonal spawning patterns and observed growth rates in these regions match the patterns of SFG generated by the model. The sensitivity of SFG to the variations in food and temperature increases with scallop size. Large scallops are more likely to experience low or negative SFGs than smaller ones, implying that the habitats shrink as scallops grow older/bigger. This study provides key information about scallop growth potential and biogeography from the perspective of energy balance, thus helping the development of adaptive fisheries management strategies.

U.S. exempted fishing permits: Role, value, and lessons learned for adaptive fisheries management

Experimental fishing is a powerful tool to support adaptive management by exploring innovative fisheries practices, scientific approaches, and management actions. In the United States, capacity and interest exist to use on-the-water experimentation to test alternative ideas to meet the national standards of the Magnuson-Stevens Act and promote sustainable fisheries. One program, the U.S. exempted fishing permit (EFP) program, administered by the National Oceanic and Atmospheric Administration (NOAA) within federal waters (3–200 nautical miles offshore), promotes experimentation as a collaborative process between scientists, managers, and industry to develop creative solutions to evolving fisheries challenges. Over a period of 11 years, 953 EFPs were issued in federal fisheries in the United States. Yet, to date no comprehensive analysis of the impacts, challenges, and lessons learned have been documented across the EFP program. Here, we developed the first standardized nationwide database of EFPs in the U.S. and generated an overview of the program aimed at providing key lessons for managers, fishers, scientists, and industry. The study evaluated the program at both the national and regional levels defined by NOAA. We found that EFP projects that are industry-led, inclusive of more study participants, and with strong scientific and programmatic support by partners were more informative to management outcomes. While programmatic differences between NOAA regions contributed to project outcomes and their connection to management, all regional programs would benefit from stronger documentation and a standardized database to facilitate program review and learning across regions to strengthen the utility of the EFP program more broadly.

The dynamics of the fishing fleet in China Seas: A glimpse through AIS monitoring

Monitoring fishing activities is crucial for marine conservation but challenging in practice, because the ability in tracking fisheries has been limited on varying spatial and temporal scales. The challenge is for both developed and developing countries, and is outstanding in China which is characterized by the world's largest fishing fleet. The advance of Automatic Identification System (AIS) provides the opportunity to enforce monitoring and to promote the compliance of responsible fisheries. Here, the dynamics of fishing fleets in China Seas were integrally investigated for the first time. We demonstrated heavy fishing efforts widely distributed across China Seas, whereas most vessels were concentrated along the coastal line. The temporal pattern of fishing efforts was dominated by summer moratorium, and intensive fishing occurred immediately before and after the moratorium. We highlight that most fishing activities occurred in a remarkably limited spatial and temporal scope, particularly trawling vessels which spent a few months on fishing every year and covered a small geographical area. Additionally, considerable fishing efforts have transferred from Eastern China Sea to the coastal areas of south China in response to an extension of summer moratorium, which requires the fishing moratorium beginning one month earlier since 2017. We argue that summer moratorium cannot effectively control overall fishing efforts, but rearrange the same level of efforts in space and time. We highlight caveats in the interpretation of AIS data in terms of reception issues, meanwhile the novel information provided by AIS can refine the understanding of fleet dynamics and contribute to adaptive fisheries management over broad spatial and temporal scales.

Influences of Climate Change and Variability on Estuarine Ecosystems: An Impact Study in Selected European, South American and Asian Countries.

It is well-known that climate change significantly impacts ecosystems (at the macro-level) and individual species (at the micro-level). Among the former, estuaries are the most vulnerable and affected ecosystems. However, despite the strong relations between climate change and estuaries, there is a gap in the literature regarding international studies across different regions investigating the impacts of climate change and variability on estuaries in different geographical zones. This paper addresses this need and reviews the impacts of climate change, variability and extreme weather on estuaries. It emphasises the following: (i) a set of climate parameters governing estuarine hydrology and processes; and (ii) a sample of countries in Asia (Bangladesh), Europe (Portugal) and South America (Uruguay). We reviewed the influences of the climatic drivers of the estuarine hydrology, ecological processes and specific species in estuarine communities across the selected geographical regions, along with an analysis of their long-term implications. The key results from the three estuaries are as following: (i) Hilsa fish, of which the catches contribute to 10% of the total earnings of the fishery sector (1% of GDP), are affected by climate-forced hydrological and productivity changes in the Meghna; (ii) extreme droughts and short-term severe precipitation have driven the long-term abundance and spatial distribution of both fish larvae and juveniles/adults in the Mondego; and (iii) the river inflow and fluctuations increases since the early 1970s have contributed to variations in the salinity, the stratification, the oxygen, nutrient and trophic levels and the spatial pattern for the life stages of planktonic species, fish biomass and captures in the Rio de la Plata. The results suggested that immediate action is needed to reduce the vulnerability of estuaries to climate stressors, mainly the changing river flows, storms and sea-level rise. As a contribution to addressing current problems, we described a set of adaptation strategies to foster climate resilience and adaptive capacity (e.g., early-warning systems, dam management to prevent overflows and adaptive fisheries management). The implications of this paper are two-fold. Firstly, it showcases a variety of problems that estuaries face from changing climate conditions. Secondly, the paper outlines the need for suitable adaptive management strategies to safeguard the integrity of such vital ecosystems.