Adaptive spatiotemporal management to reduce shark bycatch in tuna fisheries.

Purse-seine tropical tuna fishing in the eastern tropical Pacific Ocean (EPO) results in the bycatch of several sensitive species groups, including elasmobranchs. Effective ecosystem management balances conservation and resource use and requires considering trade-offs and synergies. Seasonal and adaptive spatial measures can reduce fisheries impacts on nontarget species while maintaining or increasing target catches. Identifying persistently high-risk areas in the open ocean, where dynamic environmental conditions drive changes in species' distributions, is essential for exploring the impact of fisheries closures. We used fisheries observer data collected from 1995 to 2021 to explore the spatiotemporal persistence of areas of high bycatch risk for 2 species of oceanic sharks, silky shark (Carcharhinus falciformis) and oceanic whitetip shark (Carcharhinus longimanus), and of low tuna catch rates. We analyzed data collected by fisheries scientific observers onboard approximately 200 large purse-seine vessels operating in the EPO under 10 different flags. Fishing effort, catch, and bycatch data were aggregated spatially and temporally at 1° × 1° cells and monthly, respectively. When areas of high fishing inefficiency were closed the entire study period and effort was reallocated proportionally to reflect historical effort patterns, yearly tuna catch appeared to increase by 1-11%, whereas bycatch of silky and oceanic whitetip sharks decreased by 10-19% and 9%, respectively. Prior to fishing effort redistribution, bycatch reductions accrued to 21-41% and 14% for silky and oceanic whitetip sharks, respectively. Our results are consistent with previous findings and demonstrate the high potential for reducing elasmobranch bycatch in the EPO without compromising catch rates of target tuna species. They also highlight the need to consider new dynamic and adaptive management measures to more efficiently fulfill conservation and sustainability objectives for exploited resources in the EPO.

Gestión espaciotemporal adaptativa para reducir la captura incidental de tiburones en la pesca del atún Resumen La pesca con cerco del atún tropical en el Pacífico Tropical Oriental (PTO) resulta en la captura incidental de varios grupos de especies sensibles, incluidos los elasmobranquios. La gestión eficiente del ecosistema equilibra la conservación y el uso de recursos y requiere que se consideren las compensaciones y las sinergias. Las medidas espaciales adaptativas y estacionales pueden reducir el impacto de las pesquerías sobre las especies accesorias mientras mantienen o incrementan la captura intencional. La identificación de las áreas con alto riesgo persistente en mar abierto, en donde las condiciones ambientales dinámicas causan cambios en la distribución de las especies, es esencial para explorar el impacto del cierre de las pesquerías. Usamos datos de observadores de las pesquerías recolectados entre 1995 y 2021 para explorar la persistencia espaciotemporal de las áreas con alto riesgo de captura incidental para dos especies de tiburón (Carcharhinus falciformi y C. longimanus) y con tasas bajas de captura de atún. Analizamos los datos recolectados por los observadores científicos de las pesquerías a bordo de aproximadamente 200 embarcaciones grandes de pesca con cerco que operaban en el PTO bajo diez banderas diferentes. Agregamos los datos sobre el esfuerzo de pesca, captura y la captura incidental de forma espacial y temporal en celdas de 1° x 1° y mensual, respectivamente. Cuando las áreas con gran ineficiencia pesquera se encontraban cerradas durante toda la investigación y el esfuerzo se reasignaba proporcionalmente para reflejar los patrones históricos de esfuerzo, el esfuerzo anual de captura de atún parecía incrementar en un 1­11%, mientras que la captura incidental de las dos especies de tiburones disminuía en un 10­19% (C. falciformi) y 9% (C. longimanus). Antes de que de redistribuyera el esfuerzo de pesca, la reducción de la captura incidental se acumuló hasta el 21­41% (C. falciformi) y 14% (C. longimanus). Nuestros resultados son congruentes con resultados previos y demuestran el gran potencial de reducción de la captura incidental de elasmobranquios en el PTO sin poner en peligro las tasas de captura de las especies de atún. Los resultados también enfatizan la necesidad de considerar medidas adaptativas nuevas y dinámicas para cumplir de forma más eficiente los objetivos de conservación y sustentabilidad para la explotación de recursos en el PTO.

The importance of migratory connectivity for global ocean policy.

The distributions of migratory species in the ocean span local, national and international jurisdictions. Across these ecologically interconnected regions, migratory marine species interact with anthropogenic stressors throughout their lives. Migratory connectivity, the geographical linking of individuals and populations throughout their migratory cycles, influences how spatial and temporal dynamics of stressors affect migratory animals and scale up to influence population abundance, distribution and species persistence. Population declines of many migratory marine species have led to calls for connectivity knowledge, especially insights from animal tracking studies, to be more systematically and synthetically incorporated into decision-making. Inclusion of migratory connectivity in the design of conservation and management measures is critical to ensure they are appropriate for the level of risk associated with various degrees of connectivity. Three mechanisms exist to incorporate migratory connectivity into international marine policy which guides conservation implementation: site-selection criteria, network design criteria and policy recommendations. Here, we review the concept of migratory connectivity and its use in international policy, and describe the Migratory Connectivity in the Ocean system, a migratory connectivity evidence-base for the ocean. We propose that without such collaboration focused on migratory connectivity, efforts to effectively conserve these critical species across jurisdictions will have limited effect.

Scientific mobilization of keystone actors for biosphere stewardship.

The biosphere crisis requires changes to existing business practices. We ask how corporations can become sustainability leaders, when constrained by multiple barriers to collaboration for biosphere stewardship. We describe how scientists motivated, inspired and engaged with ten of the world's largest seafood companies, in a collaborative process aimed to enable science-based and systemic transformations (2015-2021). CEOs faced multiple industry crises in 2015 that incentivized novel approaches. New scientific insights, an invitation to collaborate, and a bold vision of transformative change towards ocean stewardship, created new opportunities and direction. Co-creation of solutions resulted in new knowledge and trust, a joint agenda for action, new capacities, international recognition, formalization of an organization, increased policy influence, time-bound goals, and convergence of corporate change. Independently funded scientists helped remove barriers to cooperation, provided means for reflection, and guided corporate strategies and actions toward ocean stewardship. By 2021, multiple individuals exercised leadership and the initiative had transitioned from preliminary and uncomfortable conversations, to a dynamic, operational organization, with capacity to perform global leadership in the seafood industry. Mobilizing transformational agency through learning, collaboration, and innovation represents a cultural evolution with potential to redirect and accelerate corporate action, to the benefit of business, people and the planet.

Integrating climate adaptation and biodiversity conservation in the global ocean.

The impacts of climate change and the socioecological challenges they present are ubiquitous and increasingly severe. Practical efforts to operationalize climate-responsive design and management in the global network of marine protected areas (MPAs) are required to ensure long-term effectiveness for safeguarding marine biodiversity and ecosystem services. Here, we review progress in integrating climate change adaptation into MPA design and management and provide eight recommendations to expedite this process. Climate-smart management objectives should become the default for all protected areas, and made into an explicit international policy target. Furthermore, incentives to use more dynamic management tools would increase the climate change responsiveness of the MPA network as a whole. Given ongoing negotiations on international conservation targets, now is the ideal time to proactively reform management of the global seascape for the dynamic climate-biodiversity reality.

The environmental niche of the global high seas pelagic longline fleet.

International interest in the protection and sustainable use of high seas biodiversity has grown in recent years. There is an opportunity for new technologies to enable improvements in management of these areas beyond national jurisdiction. We explore the spatial ecology and drivers of the global distribution of the high seas longline fishing fleet by creating predictive models of the distribution of fishing effort from newly available automatic identification system (AIS) data. Our results show how longline fishing effort can be predicted using environmental variables, many related to the expected distribution of the species targeted by longliners. We also find that the longline fleet has seasonal environmental preferences (for example, increased importance of cooler surface waters during boreal summer) and may only be using 38 to 64% of the available environmentally suitable fishing habitat. Possible explanations include misclassification of fishing effort, incomplete AIS coverage, or how potential range contractions of pelagic species may have reduced the abundance of fishing habitats in the open ocean.