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Oxygen is crucial for the survival of marine species. Yet, the ocean has experienced a loss of approximately 2% of its oxygen inventory since the last century, resulting in adverse impacts on marine life and ecosystems. In particular, changes in the gap between the supply and demand for dissolved oxygen lead to physiological and ecological variations, which cause alterations in habitats and food webs for fish and ecosystem services. These changes vary over time and by region, and the heterogeneous characteristics of marine species bring about non-linear consequences to human society. Despite this, identifying the potential ripple effects of deoxygenation on human society is challenging due to the integrated impacts of other stressors, such as global warming and ocean acidification, and their varying changes depending on environmental conditions and regions, such as upwelling and eutrophication. Therefore, we conducted a literature review on ocean deoxygenation and its effects on fish dynamics and the ecosystem, with a focus on the environmental and societal impact, to present crucial considerations and pathways for future research on ocean deoxygenation. We found that quantitative approaches are necessary to assess the dynamic changes under deoxygenation, and the consequent effects on marine ecosystems should be verified to exploit the natural resources from the ocean. One of the most reliable approaches to quantifying the ripple impacts of deoxygenation is to model spatial and temporal changes with other climate stressors, forming a global network encompassing socio-economic and regional effects of this global change to facilitate and improve capabilities to address the impacts of ocean deoxygenation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Accounts of fishing conflicts have been rising globally, particularly between small-scale and industrial vessels. These conflicts involve verbal or physical altercations, and may include destruction of boats, assault, kidnapping, and murder. Current scholarship around industrial/small-scale fishing conflicts theorizes them as a form of resource conflict, where fish scarcity is the dominant contributor to conflict and competition. Alternatively, conflicts may be driven by spatial competition, concentrating where there are increased encounters, unrelated to resource status. Current policies to address these conflicts focus on enforcing the separation of small-scale and industrial vessels; however, this broad spatial separation has yet to be evaluated for deterring conflicts. Here we employ a novel spatial analysis to estimate the locations of industrial/small-scale conflicts at sea in Ghana, West Africa. Using data from narrative reports over the period of 1985 to 2014, we combine qualitative information on depth and shoreline indicators to analyze conflict locations. We find virtually all expected conflict locations (98%) occurred within the zone meant to exclude industrial vessels, and conflicts concentrated primarily around major ports. Our results suggest conflicts are likely more related to spatial patterns of vessel presence than patterns of resource use. These findings suggest a critical need for evidence-based and contextual information on the drivers of fisheries conflicts, rather than continued reliance on assumptions of resource scarcity. They also suggest that nuanced policies that reduce vessel encounter and clarify exclusive spatial rights may be more important in responding to these conflicts than approaches designed to broadly separate fleets or increase fish stocks. [ABSTRACT FROM AUTHOR]

The magnitude of subsidies provided to the fishing sector by governments worldwide is immense—an estimated $35.4 billion USD per year. The majority of these subsidies may be impeding efforts to sustainably manage fisheries by incentivizing overfishing and overcapacity. Recognizing the threat these subsidies pose, the World Trade Organization has set a goal of reaching an agreement that would end fisheries subsidies that contribute to overcapacity, overfishing, and illegal fishing. However, negotiations have been hampered by uncertainty around the likely effects of reforming these subsidies. Here we present a novel method for translating a bioeconomic model into an interactive online decision support tool that draws upon real-world data on fisheries subsidies and industrial fishing activity so users can directly compare the relative ambition levels of different subsidy reform options. [ABSTRACT FROM AUTHOR]

Arctic sea ice loss has direct consequences for predators. Climate‐driven distribution shifts of native and invasive prey species may exacerbate these consequences. We assessed potential changes by modelling the prey base of a widely distributed Arctic predator (ringed seal; Pusa hispida) in a sentinel area for change (Hudson Bay) under high‐ and low‐greenhouse gas emission scenarios from 1950 to 2100. All changes were relatively negligible under the low‐emission scenario, but under the high‐emission scenario, we projected a 50% decline in the abundance of the well‐distributed, ice‐adapted and energy‐rich Arctic cod (Boreogadus saida) and an increase in the abundance of smaller temperate‐associated fish in southern and coastal areas. Furthermore, our model predicted that all fish species declined in mean body size, but a 29% increase in total prey biomass. Declines in energy‐rich prey and restrictions in their spatial range are likely to have cascading effects on Arctic predators. [ABSTRACT FROM AUTHOR]