Fish and Fisheries最新文献

Targeted management interventions can influence marine resource user behaviour, yet some remain ineffective. Behavioural economics may offer valuable insights on this topic by identifying which interventions can effectively change human behaviour and how they can be applied. This systematic review (N = 140) synthesises evidence from behavioural economics studies conducted in a fisheries context. The results include a table of behavioural mechanisms and examples of evidence for behavioural interventions changing environmental, economic, and social outcomes. There is a growing body of evidence that interventions that activate mechanisms such as social norms or risk aversion can impact environmental outcomes. However, there is a general lack of explicit reporting of the link between behavioural mechanisms, interventions, and outcomes, revealing weak conceptualisation in the field. This hinders the ability of scientists, practitioners, and policymakers to derive actionable insights from the research. Furthermore, the ethics of intervening in human behaviour as well as thorough analysis of unintended consequences need significant attention. To resolve these issues and guide the field forward, this systematic review offers recommendations for both science and policy as well as a conceptual framework that can improve the design of future studies that aim to understand human behaviour in a fisheries setting.

Sustainable commercial fishing makes valuable contributions to coastal regions and broader national benefits. This paper offers three arguments in relation to what is required for the societal benefits of sustainable fisheries to be fully realised and considers each in the context of the UK but with global relevance. First, there is a need to raise the profile of the full range of benefits that are delivered through sustainable fisheries to coastal communities and the broader public. In the UK, the delivery of a ‘national benefit’ objective through fisheries is now enshrined in law by the Fisheries Act, 2020; we operationalise this through a new framing that distils eight ‘national benefits’ that all sustainable fisheries should deliver. Second, better acknowledgement of what society gains from sustainable fisheries must be paralleled with recognition of what society is simultaneously at risk of losing through the decline of the fishing fleet. We detail this decline in a new analysis of long-term UK data, which highlights that the decline is unequally felt, with some regions of the UK, and small-scale fishing sectors, experiencing loss more acutely. This reality leads us to argue a third point, that if society is to retain and truly harness the benefits that flow from sustainable fisheries, governing bodies must act quickly to ensure that fisheries are environmentally sustainable, diverse and inclusive, pursuing fisheries that ‘leave no one behind’.

Across Alaska, there have been synchronous declines in the abundance, mean age, and size of Chinook salmon (Oncorhynchus tshawytscha, Salmonidae), a species with immense social and ecological importance. The decline of Chinook salmon, and regulations addressing declines, have drastically impacted people who rely on Alaska's fisheries. Despite their importance, the drivers causing Chinook salmon declines are still not well understood. Therefore, to improve our understanding of the likely drivers of these large-scale synchronous declines, we synthesised the peer-reviewed Chinook salmon literature published between 2010 and 2024 using a weight-of-evidence approach. We identified 94 variables used to explain the trends in abundance and demographics of Chinook salmon. Each variable's association with trends in Chinook salmon was individually assessed and integrated using a standardised method. Results of this synthesis suggest the drivers for large-scale synchronous declines have occurred in the North Pacific Ocean. Specifically, we found marine predation, size selective harvest, and pink salmon (Oncorhynchus gorbuscha) abundance are the factors most strongly associated with reduced size and age. Results also suggest ocean productivity–specifically winter sea surface temperature and the North Pacific Gyre Oscillation–are the most frequently identified predictors of regional Chinook salmon abundance. In addition to addressing freshwater factors like adult heat stress and juvenile predation, we suggest research, policy, and management focus on how to better understand and address the interactions between ocean productivity, marine predation, size selective harvest, and pink salmon abundance to improve the condition of Chinook salmon, and the people and ecosystems benefiting from them.

Animal body size distributions result from interactions of growth, mortality and recruitment. In ecology and fisheries science, theoretical models of fish body size distributions are widely used but rely on life-history parameters—growth coefficient (K) and natural mortality rate (M)—that remain unknown for most species and are challenging to estimate. Analysing data from underwater visual surveys and exhaustive sampling, representing 3068 populations across 797 species of shallow-water, mostly unfished marine fishes, we demonstrate that post-recruitment body length distributions exhibit a consistent unimodal shape across species and populations. When scaled to the mean body length, these distributions are strikingly similar across all teleost and elasmobranch species, with diverse life histories and maximum body sizes ranging from 1 cm to 3 m. Observed size structure can be approximated by a truncated normal distribution with a coefficient of variation of ~0.34 (SE = 0.002). Such consistent observed body size distributions could be aligned with Beverton–Holt population dynamics theory, if assuming an M/K ratio of ~1.5 and logistic observational selectivity with 50% detectability at ~40% of maximum body length. Alternatively, observed distributions could reflect deviations from theoretical expectations, and reconciling the unimodal distributions with theory may require relaxing some model assumptions, such as continuous recruitment, constant density-independent growth or constant natural mortality. Overall, the consistency of population- and species-level body length distributions means that unfished size structure could be predicted from a single body size parameter. It also suggests evolutionary convergence of diverse growth and mortality processes towards a narrow range of viable outcomes.

The life cycle of the European eel (Anguilla anguilla) is inherently risky because it relies on the successful migration of larvae and adults across thousands of kilometres of the Atlantic Ocean. In between these migrations, eels need to grow and develop to maximise their potential for successful reproduction. Eels have a number of life-history characteristics at each life stage that minimise mortality, starvation and predation risks and maximise opportunities for growth. In the larval and silver eel phases, eels select specific habitats and adopt efficient swimming behaviours to minimise predation and migration failure risks. In the glass and yellow eel phase, the opposite is the case, and plasticity and adaptability enable occupation of a broad ecological niche that maximises growth opportunities and enables a continent-wide distribution. Under natural conditions, these characteristics enable enough individuals to survive, grow and reproduce so that the population is resilient to natural risks. However, there is increasing evidence of impacts of anthropogenic activities that eels may be particularly sensitive to, resulting in a declining population with reduced resilience. Climate-linked oceanic risk factors are likely to have a significant influence on the recruitment of eels but are not well understood and cannot be easily modified. However, interventions to mitigate known impacts in the growth environment offer hope for population recovery. A greater understanding of the plasticity of the growth phase and the impacts of risks during the oceanic phase is essential to enable management interventions in the Anthropocene to be fully effective.

Fishing with active bottom-contacting gears (here collectively described as 'bottom trawling') is considered the greatest source of anthropogenic disturbance to marine sediments. However, uncertainties are apparent in studies evaluating the severity of their impacts from fishing with these gears at the global scale. A major uncertainty is the estimation of the area of seabed disturbed by applying European-based vessel size to gear footprint (i.e., gear width) relationships to the global fleet, thereby assuming these relations hold worldwide. To test the strength of this assumption, we conducted a structured review to understand global variation in fishing gear parameters and, thus, footprint of bottom trawling gears. While we find a European bias in the primary literature, we find that the relationship between vessel size and gear footprint differs significantly among FAO Major Fishing Areas, suggesting that European-based relationships are not representative of fleets worldwide. For example, otter trawler footprints in the Mediterranean and the Black Sea increase by 10.2 m for every meter increase in overall vessel length compared to just 3.3 m for otter trawlers in the Northwest Atlantic. These findings challenge the reliability of previous estimates of the global footprint of bottom trawling gears, thus highlighting the urgent need for improved availability of commercial data to create a globally representative data set that can address uncertainties in the quantification of anthropogenic disturbance of the benthic environment and the consequential impacts on biodiversity, ecosystem integrity and carbon losses.

The importance of connectivity for freshwater organisms is widely recognised, yet in-stream barriers associated with population declines and increased risk of extinction remain globally ubiquitous. Despite their negative consequences, these barriers can protect aquatic communities by limiting the spread of invasive species, leading to conflicting management goals in some regions. Selective fish passage is a solution for the conflicting goals of passing native, desirable species while restricting the spread of invasives. Approaches that can target groups of species sharing similar attributes (i.e. guilds) are likely to be more efficient than those that target species individually, particularly in taxonomically diverse systems. We explored the guild structure of 220 Great Lakes freshwater fishes based on morphological, phenological, physiological and behavioural attributes associated with passage and movement. We identified five distinct guilds as well as the attributes most important for defining these groupings: maximum total length, trophic level, relative eye size, spawning temperature, spawning season, presence/absence of ampullary electroreceptors and the presence/absence of hearing specialisations. The approaches outlined in this work can be generalised to enhance selective fish passage in aquatic ecosystems worldwide.

Small-scale fisheries (SSF) are commonly governed through co-management, a widely advocated approach for promoting equitable governance. However, evidence suggests that this governance approach can sometimes exacerbate power imbalances, facilitate elite capture and intensify conflicts. To foster co-management that successfully enhances equity in SSF governance, it is crucial to understand when and why it leads to positive or negative equity outcomes. To this end, we undertook a scoping review to identify empirical research on the relationship between SSF co-management and equity outcomes. We identified 30 empirical studies that assessed equity outcomes in SSF co-management initiatives. Our analysis revealed four key findings: (1) distributional and procedural equity received approximately equal levels of attention, largely without an explicit equity lens; (2) co-management had mixed impacts on equity, with the most prevalent outcome being improvement to equity; (3) delegated and cooperative co-management types were more often associated with improved equity outcomes, while consultative co-management was more often associated with reductions or no change; and (4) inclusive participation, strong social capital and secure property rights were most often associated with improved equity outcomes, while weak social capital, institutional design and management oversight were most often associated with reduced equity outcomes. However, the evidence supporting our findings was limited, with only seven studies robustly documenting the role of inclusive participation in enhancing equity. Our review offers valuable insights into the complex interplay between SSF co-management and equity, informing future research and practice and policy interventions aimed at achieving social goals through co-management governance approaches.