Fish and Fisheries最新文献

Acoustic telemetry offers valuable opportunities to investigate individual variability in circadian-related and other behaviours and how environmental cues shape these patterns in wild fish populations. However, this potential has not yet been fully exploited. We conducted a meta-analysis on 44 datasets from 34 distinct marine and freshwater species and different types of data (acoustic detections, depth, acceleration and positioning). Our aim was to explore the potential of acoustic telemetry in identifying chronotypes as consistent among-individual differences in circadian-related behaviours. First, we applied hidden semi-Markov models to classify individual time series into active and rest states. Subsequently, we computed two classical circadian-related behavioural traits: awakening time (as the activity onset) and rest onset (as the activity offset). Subsequently, we identified distinct phenotypes by decomposing behavioural variation into within- and among-individual components based on repeatability scores. We found evidence of distinct chronotypes in 17 species, with average repeatability scores of 0.52 for awakening time and 0.43 for rest onset, revealing that chronotypes are common in aquatic species. Our findings highlight that both the data type, particularly acceleration sensors, and the number of detections are effective tools for exploring chronotypes. Our study proposes a novel approach to characterising daily activity patterns in aquatic species, predominantly in fishes, and provides guidelines for investigating chronotypes across diverse taxa. We emphasise the promise of biotelemetry and advanced statistical models for improving our understanding of the behaviour of aquatic species and highlight the value of synthesising across large data sets collected in networks of biotelemetryprojects.

Climate change and local pressures are eroding the health and performance of many watersheds and their freshwater ecosystems, pushing these complex social-ecological systems to the boundaries of their safe operating space. Here, we offer a synthetic perspective on the downscaled application of the safe operating space concept to inform the stewardship of watersheds in this time of rapid climate change, with particular focus on watersheds that support coldwater migratory fishes such as Pacific salmon. First, we review the safe operating space concept as it applies to salmon watersheds as social-ecological systems. Salmon watersheds, and the benefits they provide for diverse peoples, are under enormous cumulative pressure from climate change as well as local activities such as forestry, urbanisation, mining and agriculture. We identify four general syndromes of dual local and climate pressures. For example, local pressures, such as the removal of riparian vegetation that shades streams, can exacerbate climate warming of water temperatures. Furthermore, extractive industries can damage or destroy future habitats and thus erode adaptive capacity. As an illustrative example of how the safe operating space concept can be operationalised, we assess alternative plausible watershed futures of land use and climate change scenarios and salmon performance. Collectively, this work showcases tangible options for local management to help give salmon watersheds the time and space to cope with climate change. More broadly, while there is a global need to address climate change, local watershed management is a key component of pathways towards freshwater sustainability and their services for humanity.

People have had a profound influence on Earth's biodiversity for millennia, culminating in Anthropocene environmental degradation and the modern biodiversity crisis. While the scale and extent of people's long-term influence on Earth's biodiversity in terrestrial and nearshore marine ecosystems are relatively well studied, there are significant questions about the antiquity and evolution of people's influence on pelagic ecosystems and organisms. We explore the Holocene history of human interactions with offshore marine organisms and ecosystems by integrating archaeological and historical perspectives on the origins and expansion of northeastern Pacific Ocean tuna (Thunnus spp.) fisheries. Indigenous people from the Pacific Coast of Canada to Baja California fished for tuna for > 5000 years, but tuna were generally not one of the most abundant species targeted by Indigenous fisheries, which largely focused on nearshore kelp forest, rocky reef and estuary habitats. The scale of Indigenous tuna fisheries is relatively small when compared to capitalist commercial fisheries, which commenced by the onset of the 20th century, rapidly accelerated during World War I and II, and declined by the mid-1980s or earlier. Although Indigenous people fished for tuna in the northeastern Pacific for millennia, significant human use of and influence on offshore ecosystems in the northeastern Pacific is primarily associated with the mid-20th century Great Acceleration and associated global ecological impacts. These data illustrate the important role of people as a driving force in marine habitats for millennia but demonstrate that strong anthropogenic influence on nearshore coastal ecosystems appeared several millennia before those of offshore ecosystems.

Issues of equity and social justice have never been more urgent than they are today, as global social disparity continues to rise. The small-scale fisheries (SSF) sector, long neglected by top-down policies and mainstream markets, remains essential to the livelihoods of millions worldwide. In this context, equity challenges are particularly pressing. This study examines Brazil's SSF sector, focusing on gender dynamics and disparities. Home to the largest SSF population in the Americas, Brazil ranks among the top countries globally in fisherwomen—with nearly 900,000 women engaged in the sector, representing half of its SSF workforce. Despite their numbers and contributions to sustainable practices, such as low bycatch rates and minimal fuel usage, fisherwomen consistently earn less than men and are largely overlooked in social protection policies. Our analysis reveals a historical and persistent underrepresentation in policy, fishery-dependent research, and social science, culminating in legal and economic imbalances—particularly in regions where fisherwomen form the majority, such as the North and Northeast. This results in reduced access to fisheries-derived income and management benefits compared to fishermen. Moreover, fisherwomen remain underrepresented in decision-making processes, despite their work aligning with key Sustainable Development Goals, including poverty reduction, gender equality, and sustainable resource management. This study offers recommendations beyond policy, including capacity-building initiatives and implementation of gender-disaggregated data systems to advance equity and social justice for Brazilian fisherwomen, providing a potential model for nations facing similar socio-environmental challenges. It aims to catalyse global dialogue and inclusive reforms that recognise, protect, and empower women in small-scale fisheries.

Local ecological knowledge (LEK) can provide insight into ecosystem change, particularly in dynamic ecological conditions, such as those driven by climate change. In New England lobster fisheries, warming waters have the potential to disrupt food webs, as range-shifting species introduce novel ecological interactions. Here we use interviews with lobster fishers in Maine and Massachusetts to understand lobster fishers' LEK of dynamic food webs, taking a mental modelling approach to construct LEK food web models under rapidly warming waters. We find that fishers are observing a remarkable range of ecological interactions across habitats, collectively reporting knowledge of > 35 species that interact trophically with lobster across larval, juvenile, and adult life stages, ranging from terrestrial species like mink (Neovison vison) to deep sea species like redfish (Sebastes fasciatus). Our LEK food webs demonstrate perceptions of warming water altering species' abundances and interactions, with an overall negative impact on lobster fisheries. Fishers also report knowledge of complex interactions, including predation, competition, and habitat loss mediated by warming waters and changing species' abundances. Finally, we identify and categorise three main pathways that contribute to fishers' LEK, including observation, word of mouth, and inference. Our findings demonstrate that active fishers have complex understandings of food web interactions in dynamic ecosystems that are changing rapidly. With management unable to keep pace with climate-driven change, fishers' LEK is an invaluable source of knowledge, whose use could improve the ability to understand the diverse impacts of warming waters on coastal ecosystems.

Conflicts are presumably pervading small-scale fishery (SSF) systems around the world due to the highly complex interactions taking place within them. To provide a deeper understanding of these conflicts and the resolution strategies in place, a literature review was conducted. Despite the unique and complex conflicts encountered, certain common patterns emerged across the studies in their drivers, stakeholders involved, intensity, responses and resolution strategies. In total, 194 publications documenting conflicts across 201 locations worldwide were analysed. Conflicts were reported both within SSF and between SSF and 13 other groups and activities, primarily with large-scale fisheries (LSF) and public authorities. Competition over resources and space, along with restrictions to fishing, were the most common drivers of conflict. These were occasionally associated with ethnics, political corruption and resentment among others. Violent responses were rather frequent, yet some cooperation strategies also emerged in the midst of tensions. Stakeholder engagement and new regulations were the most frequent strategies to de-escalate conflicts, although the efficacy of these approaches varied across locations. Although combinations of conflict resolution strategies were used in some instances, strategies were combined in no more than two or three at a time and in less than half of the de-escalated cases. This highlights a lack of multifaceted conflict resolution strategies.

Spatio-temporal species distribution models (SDMs) are valuable tools to support fisheries management, as they account for long-term and time-varying unmeasured variation (spatial and spatio-temporal variation), thereby providing more accurate and statistically efficient estimates than simpler SDMs. However, the application of spatio-temporal SDMs for probabilistic forecasts of fish abundances has been slowed by two main challenges. First, guidance surrounding the decisions needed to generate forecasts with a spatio-temporal SDM is lacking. Second, there is limited functionality to efficiently produce forecasts with spatio-temporal SDMs while also propagating uncertainty about initial conditions and process errors. We developed new approaches to forecasting with spatio-temporal SDMs, which allow for efficient predictions with spatio-temporal SDMs and quantifying the influence of different model components on prediction uncertainty. We illustrate our approaches with two contrasting applications: west coast New Zealand snapper (Chrysophrys auratus), using fisheries data and examining retrospective forecasts; and Bering Sea capelin (Mallotus villosus), employing fisheries-independent data and generating forecasts to 2100. The applications showed that spatio-temporal variation should be included in spatio-temporal SDMs to produce forecasts, to explain a much larger fraction of the variability in the data, thereby providing more accurate reconstructions of population trends and better characterising uncertainty around forecasts. Our results also highlight that forecasts with spatio-temporal SDMs work best in data-rich situations, particularly if the time series of fish data is relatively long. Our approaches can help unlock the use of spatio-temporal SDMs to make both near-term and long-term forecasts, providing better information to fisheries managers and informing future data collection.

Minimising bycatch is a pervasive challenge for sustainable fisheries management, the importance of which is amplified for non-target species or populations that are in decline. In the eastern Bering Sea (EBS) walleye pollock (Gadus chalcogrammus) fishery, salmon—most notably Chinook (Oncorhynchus tshawytscha) and chum (O. keta)—are encountered as bycatch. Salmon bycatch in the EBS pollock fishery has become an issue of growing concern, largely due to declines in Western Alaska Chinook and chum salmon, which support directed fisheries vital to the wellbeing of regional communities. Consequently, minimising salmon bycatch is a management priority and requires information on the underlying processes driving encounters between salmon and pollock vessels. In this study, we present a broad synthesis of Chinook and chum salmon bycatch dynamics in the EBS pollock fishery. Applying a hierarchical modelling framework to nearly 120,000 catch records collected over 13 years (2011–2023), we quantify patterns of variation in salmon bycatch over space and time, and environmental drivers thereof. Our results reveal spatially structured, interannual variation in chum and Chinook salmon bycatch associated with oceanographic conditions. We also demonstrate the importance of interactions between bottom depth and local sea surface temperature anomalies in shaping bycatch rates, which vary across fishing seasons and salmon species. By advancing our understanding of the factors that contribute to encounters between pollock vessels and salmon, this study can inform ongoing management efforts aimed at minimising multispecies salmon bycatch in a changing marine ecosystem.

Between 1989 and 2007, 28 Distinct Population Segments (DPS) of Pacific salmon (Oncorhynchus spp.) spawning in rivers in California and the Pacific Northwest (Oregon, Washington, Idaho) were listed (protected) under the US Endangered Species Act (ESA). In the roughly 25 years since then, considerable efforts have been made to recover these populations, but no DPS has increased sufficiently to be delisted. We evaluated abundance trends of ESA-listed Pacific salmon DPS, along with DPS that were not ESA-listed. Our goal was to evaluate whether protected DPS increased in abundance during the period of protection (nominally 1995–2020 in our study), either in absolute terms or relative to the unprotected DPS. A majority of the protected DPS had increasing abundance trends over this time period, and protected populations had higher median trends than non-protected populations of the same species. Geographically, populations in the Pacific Northwest had higher median trends than those in California. Among species of protected populations, Chinook salmon (O. tshawytscha), chum salmon (O. keta) and sockeye salmon (O. nerka) had higher median trends than coho salmon (O. kisutch) and steelhead (anadromous O. mykiss). For most DPS (listed and unlisted), trends in harvest rates and hatchery releases were relatively stable during the same time period, whereas trends in indicators related to freshwater and marine climate were generally negative for salmon. Our results suggest that salmon recovery actions may have helped to stabilise and increase protected DPS, but most remain far below their recovery goals.