Jon Lopez

Climate Vulnerability Assessments (CVAs) are important tools for understanding and addressing the impacts of climate change on marine fisheries. Since their introduction in the 1990s, CVAs have evolved from theoretical frameworks to practical applications aimed at fostering climate‐resilient fisheries management. This review synthesises recent advancements in CVAs, focusing on methodologies, geographic applications, stakeholder participation and their contributions to fisheries management. While many CVAs emphasise ecological or social dimensions, recent efforts have integrated these components, offering holistic insights into the vulnerabilities of fisheries as coupled socio‐ecological systems. Key innovations include participatory approaches that incorporate expert knowledge and stakeholder input alongside advances in quantitative modelling and spatially explicit analyses. Our review highlights specific examples where CVAs have informed various management applications, such as species protection under the U.S. Endangered Species Act and the design of adaptive harvest strategies in Australia. However, barriers remain, including inconsistent methodological standards, limited uptake in nations with low‐income economies and challenges translating CVA outputs into actionable policies. Looking ahead, developing generalised, integrated frameworks that bridge ecological and social dimensions, identifying ways to link CVA outputs to management guidance, and improving methodologies for data‐limited contexts will all improve uptake and application of CVAs. Strengthening the connections between existing CVAs and climate‐ready fisheries through adaptive management strategies can support fisheries management outcomes in a changing climate while balancing ecological sustainability and socio‐economic equity.

The biological impacts of climate change on ocean ecosystems and fisheries are an increasing global concern, influencing fish distribution, phenology, and productivity. To address these challenges, fisheries management agencies are developing climate-informed strategies to build resilience in marine species, ecosystems, and fisheries. Climate vulnerability assessments (CVAs) have been widely used to evaluate the vulnerabilities of species, ecosystems, fisheries, and communities to climate change, but their uptake in decision making has been limited. Here, we explore the factors that are hindering broader adoption and integration of CVA results into active fisheries management. We identify the critical components of a next-generation CVA framework that is dynamic, adaptive, and better suited to support climate responses and adaptation by fishers, fisheries managers, and coastal communities. These elements will serve to improve applicability of CVAs while emphasizing the integration of qualitative and quantitative data, including experiential knowledge, embracing dynamic models, and quantifying uncertainty to create impactful spatially and temporally explicit vulnerability assessments. The proposed changes to existing CVA approaches aim to improve fisheries management by more explicitly linking ecological and socio-economic systems and providing actionable insights for climate-resilient fisheries. These components also better align CVAs with ongoing efforts by various government initiatives and offer a path forward for improving the climate resilience of fisheries and coastal communities.

Bycatch in global tropical tuna purse seine fisheries represents a significant source of mortality for manta and devil rays (mobulids), which are globally threatened. Use of best handling and rapid release practices on purse seine vessels can substantially reduce mortality and improve vulnerability status for mobulids. However, interventions must be effective, operationally feasible, and safe for human operators if they are to be successfully implemented at a large scale. We assessed the feasibility and efficacy of an innovative mobulid bycatch release device (sorting grid) in collaboration with captains and crew of vessels in the tropical tuna purse seine fleet. We evaluated the size of individuals and duration of release when the sorting grid was used and compared these metrics with other release methods. Forty‐one mobulid capture events occurred on 12 vessels. Mobulids released using the sorting grid were significantly larger than those released by other methods; yet, mean handling time remained short (∼3 min), suggesting that the device enables the rapid release of even the largest individuals. Widespread implementation and use of the mobulid sorting grid could help achieve conservation goals for threatened mobulid rays and may have broader bycatch reduction benefits. Adoption of sorting grid requirements by regional fisheries management organizations could standardize best practices and markedly improve the survival of released mobulid rays globally.

The Silky Shark (Carcharhinus falciformis) is highly vulnerable to population decline, yet leads shark bycatch in some of the world’s largest tuna fisheries. As such, this species provides an appropriate case study for regional fisheries management organizations—exemplified by the Inter-American Tropical Tuna Commission—to develop conceptual population assessment frameworks that integrate diverse data streams to elucidate population structure and dynamics of assessed species. Using genetic, movement, life history, and small- and large-scale fishery-dependent data from across much of the Silky Shark’s Pacific Ocean range, we found preliminary evidence for a three-stock model—southern, central, and northern—in the eastern Pacific Ocean (EPO). Length distributions of Silky Sharks varied with latitude and across fishery gears and strategies. The predominance of small juveniles, including neonates, caught on or near the continental shelf by small-scale fisheries and offshore by purse seines set on floating objects, including fish aggregating devices, suggested that Silky Sharks use both shelf-edge habitats and offshore areas as pupping and/or nursery areas. Finally, we showed that sex ratios favored females in oceanic and equatorial zones, where most Silky Shark bycatch in large-scale fisheries occurs. Our study serves as a roadmap to comprehensively understand spatial population dynamics of common bycatch species lacking a dispersive larval phase, such as elasmobranchs, by integrating genetic, biological, ecological, and fisheries data. Specifically, our work can inform stock assessments and management measures that may improve Silky Shark conservation in the EPO and elsewhere.

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.

Purse‐seine fishers using drifting fish aggregating devices (dFADs), mainly built with bamboo, plastic buoys, and plastic netting, to aggregate and catch tropical tuna, deploy 46,000–65,000 dFADs per year in the Pacific Ocean. Some of the major concerns associated with this widespread fishing device are potential entanglement of sea turtles and other marine fauna in dFAD netting; marine debris and pollution; and potential ecological damage via stranding on coral reefs, beaches, and other essential habitats for marine fauna. To assess and quantify the potential connectivity (number of dFADs deployed in an area and arriving in another area) between dFAD deployment areas and important oceanic or coastal habitat of critically endangered leatherback ( Dermochelys coriacea ) and hawksbill ( Eretmochelys imbricata ) sea turtles in the Pacific Ocean, we conducted passive‐drift Lagrangian experiments with simulated dFAD drift profiles and compared them with known important sea turtle areas. Up to 60% of dFADs from equatorial areas were arriving in essential sea turtle habitats. Connectivity was less when only areas where dFADs are currently deployed were used. Our simulations identified potential regions of dFAD interactions with migration and feeding habitats of the east Pacific leatherback turtle in the tropical southeastern Pacific Ocean; coastal habitats of leatherback and hawksbill in the western Pacific (e.g., archipelagic zones of Indonesia, Papua New Guinea, and Solomon Islands); and foraging habitat of leatherback in a large equatorial area south of Hawaii. Additional research is needed to estimate entanglements of sea turtles with dFADs at sea and to quantify the likely changes in connectivity and distribution of dFADs under new management measures, such as use of alternative nonentangling dFAD designs that biodegrade, or changes in deployment strategies, such as shifting locations.

The Eastern Pacific population of leatherback turtles Dermochelys coriacea is Critically Endangered, with incidental capture in coastal and pelagic fisheries as one of the major causes. Given the population’s broad geographic range, status, and extensive overlap with fisheries throughout the region, identifying areas of high importance is essential for effective conservation and management. In this study, we created a machine-learning species distribution model trained with remotely sensed environmental data and fishery-dependent leatherback presence (n = 1088) and absence data (>500000 fishing sets with no turtle observations) from industrial and small-scale fisheries that operated in the eastern Pacific Ocean between 1995 and 2020. The data were obtained through a participatory collaboration between the Inter-American Convention for the Protection and Conservation of Sea Turtles and the Inter-American Tropical Tuna Commission as well as non-governmental organizations to support the quantification of leatherback vulnerability to fisheries bycatch. A daily process was applied to predict the probability of leatherback occurrence as a function of dynamic and static environmental covariates. Coastal areas throughout the region were highlighted as important habitats, particularly highly productive feeding areas over the continental shelf of Ecuador, Peru, and offshore from Chile, and breeding areas off Mexico and Central America. Our model served as the basis to quantify leatherback vulnerability to fisheries bycatch and the potential efficacy of conservation and management measures (Griffiths & Wallace et al. 2024; Endang Species Res 53:295-326). In addition, this approach can provide a modeling framework for other data-limited vulnerable populations and species.

Fishers have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas. DFADs increase purse‐seine efficiency, potentially increasing tuna fishing mortality. They could also have impacts on tuna natural mortality and reproductive potential, and assessing the consequences of their presence at sea on tuna populations is a challenge. The use of DFADs results in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no converging scientific results exist regarding the effects of DFADs on the large‐scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free‐swimming school. However, it is not clear whether this is the cause or the consequence of the association nor if it has long‐term effects on individuals' fitness. Further scientific progress requires (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness, and population dynamics and (ii) experimental studies to identify the underlying behavioural and biological processes involved in associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long‐term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing.

Manta and devil rays (Mobulids) face several immediate threats, including incidental capture in industrial tropical tuna fisheries. As a result, efforts have emerged to avoid or mitigate Mobulid bycatch in these fisheries. However, many mitigation efforts fail to incorporate fisher expertise from the outset, potentially leading to interventions that are not viable. Here, we combine survey and focus group data to synthesize knowledge of Mobulid bycatch and mitigation ideas in Eastern Pacific Ocean purse seine fisheries. Primary obstacles for mitigating Mobulid bycatch, according to respondents, are: (1) an inability to sight Mobulids before capture, (2) the lack of specific equipment on board, and (3) the difficulty of releasing large individuals; we suggest that the latter two can be addressed by simple operational modifications. We also find that Mobulids are most likely to be sighted by fishers after capture, suggesting that this is an important time in the fishing operation for bycatch mitigation interventions that ensure Mobulids survive capture. To address this, we share creative ideas brought by fishers for avoidance of Mobulids. This study provides a model of how to incorporate stakeholder input in the design of bycatch technology in large-scale fisheries and could inform similar efforts around the world.

The use of fish aggregating devices (FADs) in tropical tuna fisheries has increased significantly during recent decades. Concurrently, concern about juvenile tuna mortality, bycatch, and marine debris associated with FAD fisheries increased, and this led to the implementation of FAD management measures and more sustainable designs (e.g., non-entangling or biodegradable FADs, limits on active FADs, etc.). This document reviews data collection and reporting requirements of tuna-Regional Fisheries Management Organizations (t-RFMOs) on drifting FADs and summarizes the work carried out since 2010 under the Spanish FAD management plan to create an adequate standard data collection aimed at improving science-based decision making. The aim of this study is to assist in the strengthening of data collection systems through: (1) a review of the existing data requirements, (2) a review of the status of FAD data collection worldwide and identification of data gaps, and (3) recommendations aimed at improving FAD management through the strengthening of FAD data requirements. Due to the complexities of data collection, we summarize the difficulties faced when processing the data and propose concrete and practical solutions to improve both the data collection system and information quality.