Fishing methods that reduce bycatch without compromising economic viability are of interest worldwide. We extend previous Bayesian analyses of swordfish fishing methods to new metrics that differentiate catch and bycatch performance between alternative fishing configurations. This includes a novel ratio metric for comparing target species catch rates to bycatch rates of nonmarket and protected species. We apply this method to compare standard and linked deep-set buoy gear configurations, utilizing year, month, and fishing vessel-level random effects to control for other influences on catch rates. Our framework accounts for uncertainty due to limited data and disparate sample sizes to document performance of the two methods. We estimate a catch ratio between 11-14 marketable fish per nonmarket fish for the standard buoy gear configuration, and between 13-100 marketable fish per nonmarket fish for the linked buoy gear configuration. While both configurations achieve strong performance in minimizing bycatch, the linked configuration achieved a higher ratio of market to nonmarket species catch than the standard configuration, albeit with greater modeling uncertainty due to fewer observations.

This study analyzes how changes in forage species distribution affected Coastal Pelagic Species (CPS) vessel participation and target decisions in the U.S. West Coast fishery over the 2013-2017 period. We develop discrete choice models for the choice of species targeted: Pacific sardine (Sardinops sagax), market squid (Doryteuthis opalescens), Northern anchovy (Engraulis mordax), Chub (Scomber japonicus) and Jack (Trachurus symmetricus) mackerels or other Non-CPS species, and landing port during a specific day. We estimate separate nested logit models by fleet segments, which were defined previously using cluster analysis on vessel attributes such as fished area, average annual revenue, CPS diversification, and degree of reliance on CPS. An environmentally informed species distribution model (SDM) is used as a proxy for expected availability of forage species. We find that harvesters demonstrate flexibility in their fishing strategies in response to environmental and economic conditions. The study suggests that while some decisions are state-dependent, harvesters still have the capacity for adaptation. These insights are crucial for understanding the resilience of fisheries in the face of environmental variability and for informing management strategies to support sustainable fishing into the future.

Small Pelagic Fish (SPF) exhibit large fluctuations in abundance and distribution in response to environmental variability. To maintain the resilience of fishing communities and develop effective and equitable climate adaptation strategies, improved understanding of how the fishing industry responds to spatio-temporal shifts within and across SPF populations is of critical importance. In this paper, we examine the responses of the fishing industry and resource managers to shifts in SPF availability worldwide and identify the resulting socioeconomic impacts. Leveraging SPF case studies from around the globe, we synthesize and compare the social-ecological linkages and feedbacks mediating how SPF fisheries respond to changes in marine ecosystem structure and function associated with (1) spatial shifts in species distribution and habitat availability, (2) ‘boom and bust’ population dynamics, or (3) changes in fish size and quality. Our case studies illustrate multiple paths towards the resilience of small pelagic fisheries and the fishing industry dependent upon them while emphasizing the need for increased coordination and cooperation across sectors and scales as climate change progresses. Drawing from the lessons offered by historical responses, as environmental variability increases, efforts to increase the flexibility and dynamism of SPF harvest portfolios and management strategies, licensing regimes, and international catch and allocation agreements may be required to ensure resource sustainability and human well-being.

Fishers often target multiple species. More diverse harvest portfolios may reduce income risk, increasing resilience to climate-driven changes in target species’ spatial distributions and availability. Moreover, different effects can be observed across vessels in response to the same shocks and stressors, as fishers are heterogeneous. Evaluation of climate risk across different vessel groups within a particular fishery requires consideration of heterogeneous climate impacts on the availability of multiple target species and how such changes may impact substitution behavior. Here we analyze how historical climate-driven changes in forage species distribution and the closure of the Pacific sardine fishery affected landings per vessel of three coastal pelagic species (CPS): Pacific sardine ( Sardinops sagax), market squid ( Doryteuthis opalescens), and northern anchovy ( Engraulis mordax) targeted by the U.S. West Coast CPS fleet from 2000 to 2020. Using cluster analysis, we grouped vessels into different fleet segments and estimated heterogeneous responses by fleet segment and port area. Our results show that considering heterogeneity is essential in the development of equitable and effective adaptation policies designed to mitigate the impact of changes on species availability in these fisheries.

The feeding ecology of broadbill swordfish (Xiphias gladius) in the California Current was described based on analysis of stomach contents collected by fishery observers aboard commercial drift gillnet boats from 2007 to 2014. Prey were identified to the lowest taxonomic level and diet composition was analyzed using univariate and multivariate methods. Of 299 swordfish sampled (74 to 245 cm eye-to-fork length), 292 non-empty stomachs contained remains from 60 prey taxa. Genetic analyses were used to identify prey that could not be identified visually. Diet consisted mainly of cephalopods but also included epipelagic and mesopelagic teleosts. Jumbo squid (Dosidicus gigas) and Gonatopsis borealis were the most important prey based on the geometric index of importance. Swordfish diet varied with body size, location and year. Jumbo squid, Gonatus spp. and Pacific hake (Merluccius productus) were more important for larger swordfish, reflecting the ability of larger specimens to catch large prey. Jumbo squid, Gonatus spp. and market squid (Doryteuthis opalescens) were more important in inshore waters, while G. borealis and Pacific hake predominated offshore. Jumbo squid was more important in 2007-2010 than in 2011-2014, with Pacific hake being the most important prey item in the latter period. Diet variation by area and year probably reflects differences in swordfish preference, prey availability, prey distribution, and prey abundance. The range expansion of jumbo squid that occurred during the first decade of this century may particularly explain their prominence in swordfish diet during 2007-2010. Some factors (swordfish size, area, time period, sea surface temperature) that may influence dietary variation in swordfish were identified. Standardizing methods could make future studies more comparable for conservation monitoring purposes.

Motivated by a need for climate-informed living marine resource management, increased emphasis has been placed on regional end-to-end modeling frameworks designed to project climate impacts on marine ecosystems and evaluate the efficacy of potential management strategies under changing conditions. The 'Future Seas' project was initiated with a focus on three fisheries (Pacific sardine, swordfish, and albacore tuna) in the California Current System (CCS). This work leverages a suite of climate, ocean, ecosystem, and economic models to project physical, ecological, and socio-economic change, evaluate management strategies, and quantify uncertainty in model projections. Here we describe the components of the modeling framework, considerations underlying choices made in model development, engagement with stakeholders, and key physical, ecological, and socio-economic results to date, including projections to 2100. Our broad aims are to (i) synthesize a large body of climate and fisheries research that has been conducted, and continues, under the Future Seas umbrella, and (ii) provide insight and recommendations to those pursuing similar efforts for other applications and in other regions. In general, our results indicate that all three species will likely shift their distributions (predominantly poleward) in the future, which impacts accessibility to fishing fleets, spatial management, and quota allocation. For similar integrative climate-to-fisheries projections, we recommend attention is given to: recognizing potential biases arising from differences between the climate products used for ecological model fitting and those used for model projection; how sources of projection uncertainty are prioritized, incorporated, and communicated; and quantitatively linking scenarios - especially socio-economic scenarios - with climate and ecological projections.

The basis of natural resource management is decision making under uncertainty while balancing competing objectives. Within fisheries management, a process described as management strategy evaluation (MSE) is becoming increasingly requested globally to develop and test management procedures. In a fisheries or other natural resource context, a management procedure is a rule that predetermines the management response given feedback from the resource and is simulation tested to be robust to multiple uncertainties. MSEs are distinguished from other risk or simulation analyses by the explicit testing of the feedback mechanism that applies decision rule-based management advice back to the simulated population or ecosystem. Stakeholder input is frequently cited as a best practice in the MSE process, since it fosters communication and facilitates buy-in to the process. Nevertheless, due to the substantial additional cost, time requirement, and necessary scientific personnel, full stakeholder MSEs remain relatively uncommon. With this communication, we provide guidance on what constitutes an MSE, when MSEs should be undertaken or where simpler approaches may suffice, and how to prioritize the degree of stakeholder participation.

Predicting the biological impacts of new or expanding fisheries presents challenges due to limited data, high variability in catch rates, and the often low frequency of bycatch events. These issues arose in the case of the West Coast deep-set buoy gear (DSBG) fleet, which the Pacific Fisheries Management Council recommended in 2019 for authorization as a legal gear type. DSBG selectively targets swordfish (Xiphias gladius) with infrequent bycatch of other species. Limited effort and incomplete observer coverage result in a data-limited context for estimating the impacts of a fully authorized and expanded fishery. Recently, data analysts have explored Bayesian estimation for modeling rare-event bycatch in a manner that incorporates uncertainty and enables updating as more data become available. Here, we apply a Bayesian methodology to an integrated dataset of DSBG observer and logbook records to estimate bycatch rates under several plausible scenarios of DSBG authorization. We estimate posterior distributions of catch rates for three species caught in DSBG Exempted Fishing Permit (EFP) trials, and incorporate bootstrap samples of vessel-level effort to calculate posterior predictive distributions of catch counts under alternative management regimes. We discuss how our results can inform policy decisions about a new fishery with limited data, and how to extend this approach to other federal environmental actions. This approach allows policymakers to compare biological impacts of management alternatives while considering the uncertainty inherent in the predictions, and to determine whether the range of potential impacts is likely to significantly alter the affected environment.

Time-area closures are a valuable tool for mitigating fisheries bycatch. There is increasing recognition that dynamic closures, which have boundaries that vary across space and time, can be more effective than static closures at protecting mobile species in dynamic environments. We created a management strategy evaluation to compare static and dynamic closures in a simulated fishery based on the California drift gillnet swordfish fishery, with closures aimed at reducing bycatch of leatherback turtles. We tested eight operating models that varied swordfish and leatherback distributions, and within each evaluated the performance of three static and five dynamic closure strategies. We repeated this under 20 and 50% simulated observer coverage to alter the data available for closure creation. We found that static closures can be effective for reducing bycatch of species with more geographically associated distributions, but to avoid redistributing bycatch the static areas closed should be based on potential (not just observed) bycatch. Only dynamic closures were effective at reducing bycatch for more dynamic leatherback distributions, and they generally reduced bycatch risk more than they reduced target catch. Dynamic closures were less likely to redistribute fishing into rarely fished areas, by leaving open pockets of lower risk habitat, but these closures were often fragmented which would create practical challenges for fishers and managers and require a mobile fleet. Given our simulation’s catch rates, 20% observer coverage was sufficient to create useful closures and increasing coverage to 50% added only minor improvement in closure performance. Even strict static or dynamic closures reduced leatherback bycatch by only 30–50% per season, because the simulated leatherback distributions were broad and open areas contained considerable bycatch risk. Perfect knowledge of the leatherback distribution provided an additional 5–15% bycatch reduction over a dynamic closure with realistic predictive accuracy. This moderate level of bycatch reduction highlights the limitations of redistributing fishing effort to reduce bycatch of broadly distributed and rarely encountered species, and indicates that, for these species, spatial management may work best when used with other bycatch mitigation approaches. We recommend future research explores methods for considering model uncertainty in the spatial and temporal resolution of dynamic closures.

Sustainability is a common goal and catchphrase used in conjunction with seafood, but the metrics used to determine the level of sustainability are poorly defined. Although the conservation statuses of target or nontarget fish stocks associated with fisheries have been scrutinized, the relative climate impacts of different fisheries are often overlooked. Although an increasing body of research seeks to understand and mitigate the climate forcing associated with different fisheries, little effort has sought to integrate these disparate disciplines to examine the synergies and trade-offs between conservation efforts and efforts to reduce climate impacts. We quantified the climate forcing per unit of fish protein associated with several different U.S. tuna fishing fleets, among the most important capture fisheries by both volume and value. We found that skipjack tuna caught by purse seine, a gear type that is often associated with relatively high bycatch of nontarget species, results in lower climate forcing than all other sources of proteins examined with the exception of plants. Conversely, skipjack tuna caught by trolling, a gear type that is often associated with relatively low bycatch of nontarget species, generates higher climate forcing than most other protein sources with the exception of beef. Because there is a range of selectivity and climate forcing impacts associated with fishing gears, examining the trade-offs associated with bycatch and climate forcing provides an opportunity for broadening the discourse about the sustainability of seafood. A central goal of more sustainable seafood practices is to minimize environmental impacts, thus mitigation efforts-whether they target conservation, habitat preservation, or climate impacts-should consider the unintended consequences on fisheries conservation.

The Marine Stewardship Council (MSC) eco-labeling program provides fisheries a pathway to demonstrate their sustainability by undergoing an environmental certification. Like other standard-setters, the MSC’s ‘theory of change’ presumes that markets use this information to select for sustainable products, providing an incentive for producers to improve their practices and become certified. However, the underlying mechanisms which actually work to link market behavior and participation in the program in different contexts have not been systematically identified. We draw on broad MSC field experience to identify processes that have supported the theory of change in individual fisheries. Then, we develop a broadly applicable rapid assessment protocol, relying on a semi-structured interviews of key informants, to gather systematic evidence for key dynamics within the theory of change: the effects of going through MSC certification on market processes, partnerships in the fishery, and governance. In a pilot test of the protocol, we identify important common and idiosyncratic processes in three canned product fisheries: United States west coast albacore tuna, Brittany sardines, and Portuguese sardines. We find that the harvesters and buyers/processors in these fisheries sought certification primarily to expand or maintain their market share, and that certification was synergistic with stakeholder cooperation. The cases demonstrate how our rapid assessment interviews allow program participants to relate their experience in their own words yet facilitate systematic comparison to identify common mechanisms within the theory of change. We propose its wider application to systematically advance our understanding of social and economic processes that drive of eco-label interventions in different geographies and supply chains around the world.

The California drift gillnet fl eet has operated off the U.S. west coast since it developed in the late 1970's.At its full extent, fi shing effort ranged from the Southern California Bight north to Oregon.The fi shery initially targeted pelagic sharks (family Alopiidae), but shifted targets in the mid-1980's to swordfi sh, Xiphias gladius, due to the species' higher value and to the regulatory changes which created an economic advantage for targeting swordfi sh compared to thresher shark, Alopias vulpinas.Consequently the number of participants in the once-small fl eet substantially increased.Conservation concerns over the entanglement of nontarget species, including sharks, sea turtles (family Dermochelyidae and Cheloniidae), and marine mammals, led to the enactment of a series

The California Commercial Passenger Fishing Vessel (CPFV) fleet is unique in scale of operation, extensive fishing history, and economic impacts. The basses (Paralabrax sp.), which represent a principal target for the CPFV fleet, recently gained more stringent size limits and bag limits. The goal of this study was to conduct a survey of CPFV captains to assess perceptions regarding the status of two Paralabrax species, as well as the impacts of the new regulations. Catch and effort estimates were also obtained using CPFV logbook data to compare captains' perceptions with actual changes in the fishery. The captains agreed that both species are vital to recreational fishing, and that the Barred Sand Bass stock is less healthy than Kelp Bass. Catch and effort analyses were consistent with this perception, with more dramatic declines in CPUE exhibited by Barred Sand Bass. The most experienced captains perceived the status of each species to be in a less healthy state than the less experienced captains, suggesting that shifting baselines are occurring. Most of the captains thought the increased minimum size limits had the greatest short-term impact on the fishing experience. The CPFV logbook data summaries support this assertion, but Kelp Bass CPUE showed a trend reversal. In contrast, Barred Sand Bass CPUE has precipitously declined, and spawning aggregations have been absent since 2013. The agreement between captains' perceptions and logbook analyses strengthens the overall findings, and suggests captains are a valuable resource for informing fisheries management, especially in future studies with data-limited stocks.

As domestic affluence increases, nations advocate for conservation policies to protect domestic biodiversity that often curtail natural resource production activities such as fishing. If concomitant consumption patterns remain unchanged, environmentally conscious nations with high consumption rates such as the U.S. may only be distancing themselves from the negative environmental impacts associated with consuming resources and commodities produced elsewhere. This unintended displacement of ecosystem impacts, or leakage, associated with conservation policies has not been studied extensively in marine fisheries. This paper examines this topic, drawing on case studies to illustrate the ways in which unilateral marine conservation actions can shift ecosystem impacts elsewhere, as has been documented in land use interventions. The authors argue that the U.S. should recognize these distant ecological consequences and move toward greater self-sufficiency to protect its seafood security and minimize leakage as well as undertake efforts to reduce ecosystem impacts of foreign fisheries on which it relies. Six solutions are suggested for broadening the marine conservation and seafood consumption discussion to address leakage induced by U.S. policy.

Fisheries bycatch is a global threat to marine megafauna. Environmental laws require bycatch assessment for protected species, but this is difficult when bycatch is rare. Low bycatch rates, combined with low observer coverage, may lead to biased, imprecise estimates when using standard ratio estimators. Bayesian model-based approaches incorporate uncertainty, produce less volatile estimates, and enable probabilistic evaluation of estimates relative to management thresholds. Here, we demonstrate a pragmatic decision-making process that uses Bayesian model-based inferences to estimate the probability of exceeding management thresholds for bycatch in fisheries with < 100% observer coverage. Using the California drift gillnet fishery as a case study, we (1) model rates of rare-event bycatch and mortality using Bayesian Markov chain Monte Carlo estimation methods and 20 years of observer data; (2) predict unobserved counts of bycatch and mortality; (3) infer expected annual mortality; (4) determine probabilities of mortality exceeding regulatory thresholds; and (5) classify the fishery as having low, medium, or high bycatch impact using those probabilities. We focused on leatherback sea turtles (Dermochelys coriacea) and humpback whales (Megaptera novaeangliae). Candidate models included Poisson or zero-inflated Poisson likelihood, fishing effort, and a bycatch rate that varied with area, time, or regulatory regime. Regulatory regime had the strongest effect on leatherback bycatch, with the highest levels occurring prior to a regulatory change. Area had the strongest effect on humpback bycatch. Cumulative bycatch estimates for the 20-year period were 104-242 leatherbacks (52-153 deaths) and 6-50 humpbacks (0-21 deaths). The probability of exceeding a regulatory threshold under the U.S. Marine Mammal Protection Act (Potential Biological Removal, PBR) of 0.113 humpback deaths was 0.58, warranting a "medium bycatch impact" classification of the fishery. No PBR thresholds exist for leatherbacks, but the probability of exceeding an anticipated level of two deaths per year, stated as part of a U.S. Endangered Species Act assessment process, was 0.0007. The approach demonstrated here would allow managers to objectively and probabilistically classify fisheries with respect to bycatch impacts on species that have population-relevant mortality reference points, and declare with a stipulated level of certainty that bycatch did or did not exceed estimated upper bounds.

To address the tradeoff between biodiversity conservation in marine ecosystems and fishing opportunity, it is important to quantify the risk of endangered species interactions in commercial fisheries. We propose a Kalman filter suitable for rare events to estimate the endangered leatherback turtle take risk in the California drift gillnet fishery in the years 1990-2010, conditional on spatiotemporal factors that affect take rates. Results suggest interaction risk has remained stable, but with substantial variation over the spatiotemporal distribution of effort. Our methods might also apply to recreation demand analysis with rare event risk, or to applications involving irregularly spaced observations, like trade-level stock market data.

This paper develops a count data model of target species and bycatch production for an arbitrary number of species that handles correlation between species and over time. The model is applied to a large observer dataset for fishing trips taken from 1990 to 2008 for roughly 150 vessels participating in the California/ Oregon drift gillnet fishery. The fishery targets swordfish and thresher shark and produces leatherback turtle and marine mammal bycatch. Bycatch in commercial fisheries is an unwanted output which is commonly regulated by conservation measures such as quotas or time-and-area closures that directly impact the status and production of the associated fishery. Set level production is modeled within a multiproduct production system framework as conditionally dependent on temporal, spatial, technological, environmental, and regulatory explanatory variables. The model is empirically estimated utilizing the multivariate compound Poisson estimator with set level data to estimate the impact of explanatory variables on the rates of target species and bycatch production within the fishery. Empirical results suggest a statistically significant relationship between set and vessel level characteristics and production rates of target species and bycatch. The rare-event risk for protected species bycatch indicates that conservation measures to further reduce bycatch from current rates may have a statistically significant opportunity cost of target species production.

An economic activity interacts with an endangered species. The activity can be divided into mutually exclusive strata with different levels of interaction. Observing the activity in order to monitor interactions is costly. It may be desirable to manage the activity with a probability model which balances the benefit from the activity against the cost of the interaction with the endangered specie instead. The model gives rise to a permit scheme which fixates the risk of interaction over all strata and which uses the market mechanism to optimally allocate the activity between strata. The model can facilitate uncertainty in interaction rate estimates.