Pacific bluefin tuna (PBT, Thunnus orientalis) is a highly migratory species that mainly inhabits temperate regions of the North Pacific Ocean. To examine the population dynamics of this commercially and ecologically important species, it is essential to understand their spawning migration, since Northwestern Pacific Ocean is their important spawning ground. A total of three PBT were tagged with pop-up satellite archival tags (PSATs) in the spawning season (May) of 2021, and the tags remained affixed for 13, 54 and 61 days, respectively. The linear displacement ranged from 797 to 2743 km from deployment locations to pop-up locations. The deepest descent recorded was 1458 m, and the coldest temperature visited was 2.6 °C. The time spent at depth was significantly different between the daytime and nighttime, where the fish displayed regular crepuscular patterns of ascending into the surface layer at dusk and remaining there until the following dawn, when they descended past the mixed-layer depth. At the spawning grounds, PBT exhibited shallow oscillatory diving behavior and frequently visited the surface during daytime and nighttime with longitudinal movements correlated with sea surface height anomalies and mesoscale eddies. This study tracked adult PBT on their spawning grounds, and insights were gained into spawning migration, seasonal movements, and habitat use of this species in the Northwestern Pacific Ocean.

AbstractScombrids represent some of the most economically important fisheries globally. However, increased interest in creating aquaculture systems for these fish has also increased the risk for disease emergence. One such disease, Puffy Snout Syndrome (PSS), causes collagenous tissue growths on the face in numerous scombrid taxa. PSS has mainly been documented in captive-held fish populations and can lead to high mortality rates. Despite this, little is known about the causative agent(s) of PSS and the immune response they elicit. Therefore, we leveraged transcriptomic data of PSS symptomatic-captive, asymptomatic-captive, and healthy-wild Pacific Mackerel (Scomber japonicus) to evaluate the physiological characteristics of PSS infections and identify a potential mechanism of disease. Captive symptomatic and asymptomatic mackerel showed distinct gene expression patterns from their wild counterparts. Genes involved in tumorigenesis, immune response, and tissue remodeling were overexpressed in captive-held fish. WNT9 was the most overexpressed gene in captive groups, and the WNT signaling pathway itself showed a ∼3 fold increase in KEGG pathway enrichment analysis in captive animals. When captive fish were compared, asymptomatic fish showed lower expression of inflammation genes, but high expression of tumor suppressor genes compared to symptomatic-captive fish. Together, these host pathophysiological data and our past visual identification of RNA virus-like particles in afflicted tissues suggest that viral-mediated oncogenesis may be driving PSS in captive mackerel.

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.

Knowledge and scientific practice have largely been backdrops to examinations of scale and rescaling processes, including studies of rescaling environmental management. The growing use of new data technologies in environmental management highlights the need to situate knowledge and scientific practice into the politics and production of scale. Reviewing sixty years of debate over spatial management of the highly migratory and Atlantic bluefin tuna, this piece illustrates the central, dynamic roles of knowledge and scientific practice in scalar transboundary management. Findings corroborate prior studies demonstrating that stakeholders mobilize knowledge (and uncertainty) to influence spatialized management. We examine whether such practices are transformed by new data technologies, a nomenclature we adopt as “more” than big data to encapsulate and parse methods of data collection or generation, the data themselves, and the analytical techniques and infrastructures developed to make sense of data for management purposes. We find that as new data technologies reveal objects in space and time, they reformulate and multiply—rather than resolve and circumscribe—scalar management possibilities. They mix with historic scientific and political practices and are never “complete.” Beyond the bluefin case, findings point to the complications of turning to new data technologies—often uncritically celebrated for their potential to give clear, actionable data—to “solve” scalar dilemmas. Instead, they are positioned to become a new way of knowing the world: a new geo-epistemology that shapes experimentation and debate around the spatialized power relations determining control over contested spaces and the valuable resources within and moving through them.

Although steelhead (Oncorhynchus mykiss) is an iconic species found throughout the North Pacific rim, little is known about its ocean ecology. To provide insights into migratory routes and habitats occupied by steelhead in the North Pacific Ocean, we attached pop-up satellite archival tags (PSATs) to steelhead kelts in 2018 (n = 16), 2019 (n = 12), and 2020 (n = 35) from the Situk River, a robust Alaskan population. PSATs recorded extensive post-spawning migrations extending to the western North Pacific Ocean, and as far north as the central Bering Sea. While at sea, tagged steelhead spent the majority of their time in surface waters (< 5 m) and occasionally dived to 15–20 m, but displayed no observable diel depth-based behaviors. Tagged steelhead kelts experienced a thermal environment of 4–16 °C from June to January, after exiting the Situk River. Results from this project corroborate the limited past research suggesting that steelhead predominantly occupy surface waters and that their distribution is largely influenced by sea-surface temperatures of ~5–15 °C. Additionally, results from this study suggest that the waters near the Aleutian Islands are important feeding grounds for steelhead kelts from the Situk River, and thus may play a critical role in the successful reconditioning of repeat spawners in this population. These results provide the first detailed insights into the ocean ecology of steelhead and may be used for a variety of applications (e.g., niche construction, and forecasting future range dynamics under climate scenarios).

Human exploitation of marine mammals led to precipitous declines in many wild populations within the last three centuries. Legal protections enacted throughout the 20th century have enabled the recovery of many of these species and some recoveries have resulted in conflict with humans for shared resources. With legal protections and reintroduction programs, the southern sea otter (Enhydra lutris nereis) has returned to portions of its former range from which it had been extirpated for decades, causing concern that the Dungeness crab (Cancer magister) fishery could be negatively affected by increasing otter range and population size. The Dungeness crab fishery is one of the most valuable in California, and these crabs are a known prey item of sea otters. We examine sea otter population growth by port region in relation to Dungeness crab catch using landing receipts since the early 1980s. We find Dungeness crab landings and fishing success, as measured by landings per trip receipt, increased across all ports. In the most recent decade, we observed slower growth in fishing success in northern ports where otters were absent, relative to southern ports where sea otters exist and their populations have grown. In ports where otters were present, fishing success was positively correlated with otter population size over time. Further, an extensive dataset of 83,000 sea otter foraging dives identified Dungeness crab to be less than 2% of the total diet. Though we find no evidence that sea otter populations impact the Dungeness crab fishery in California, other potential conflicts could be considered before expanding reintroduction programs.

Aquaculture is an increasingly important food resource, but its sustainability is often limited by disease. In Scombridae fishes, puffy snout syndrome (PSS) is a debilitating condition where tumor-like collagenous growths form around the eyes, nares, and mandibles which impair vision and feeding and frequently lead to mortality. While PSS is considered an infectious or metabolic disease, no disease agents or promoters have been identified. Here, we used electron microscopy (EM) to describe the cellular pathology and search for etiological agents of PSS in Pacific mackerel Scomber japonicus, the first use of this approach for PSS. We examined aquaculture specimens across a range of apparent PSS severity, comparing the results to both wild and aquaculture asymptomatic mackerel. EM imagery consistently revealed viral-like particles in PSS samples, as well as the uniform absence of bacteria, protists, fungi, and other multicellular parasites. In addition to viral-like particles, symptomatic fish had a higher mean percentage of swollen and disintegrating mitochondria than both asymptomatic aquaculture and wild mackerel. This suggests that degraded mitochondria may be related to PSS and could be important to further understanding the origin, promoters, and prevention of PSS. This study serves as a first step in identifying the etiological agents of PSS.

In this article, we present and describe a new dataset of non-state actor participation in seven regional fisheries management organizations (RFMOs). The dataset contains institutional, economic and ecological variables relevant for non-state actor participation in RFMOs and for RFMO effectiveness. To code non-state actor participation and institutional factors, we quantify information from publicly available RFMO reports as well as data from the Policy IV dataset. We pair these data with existing datasets on ecological and economic factors from the RAM Legacy and the Sea Around Us databases. This article describes the data collection process and the coded variables in detail.

Analyses of the impacts of climate change on fish species have primarily considered dynamic oceanographic variables that are the output of predictive models, yet fish species distributions are determined by much more than just variables such as ocean temperature. Functionally diverse species are differentially influenced by oceanographic as well as physiographic variables such as bottom substrate, thereby influencing their ability to shift distributions. Here, we show that fish species distributions that are more associated with bottom substrate than other dynamic environmental variables have shifted significantly less over the last 30 years than species whose distributions are associated with bottom salinity. Correspondingly, species whose distributions are primarily determined by bottom temperature or ocean salinity have shifted their mean centroid and southern and northern range boundaries significantly more than species whose distributions are determined by substrate or depth. The influence of oceanographic versus static variables differs by species functional group, as benthic species distributions are more associated with substrate and they have shifted significantly less than pelagic species whose distributions are primarily associated with ocean temperatures. In conclusion, benthic fish, that are more influenced by substrate, may prove much less likely to shift distributions under future climate change.

The participation of environmental non-governmental organizations (ENGOs) in regional fisheries management organizations has inspired optimism among many observers and researchers about increasing the effectiveness of these regional organizations in managing highly migratory and straddling fish stocks sustainably. Others claim that the attendance of ENGOs in meetings of regional fisheries management organizations as accredited observers or as part of member state or cooperating non-member state delegations, could make decision- making complex, long, and inefficient. More generally, NGO participation has attracted broad scholarly interest in the study of interest groups and transnational advocacy in political science. Yet, we know little about the determinants of ENGO participation in meetings of regional fisheries management organizations in the first place. To fill this gap, this article develops a theoretical framework conceptualizing ENGO participation and developing expectations about how ecological and institutional change shapes ENGO participation. The framework deals with structural determinants of ENGO participation, as existing literature primarily has been preoccupied with the study of actor-specific explanations of specific NGOs’ impact in specific political processes. By contrast, we examine how ecological change – such as target fish stock health and biomass status – and institutional change – such as financial resources, membership composition of regional fisheries management organizations and participation by other non-state actors, such as experts and fishing industry representatives – shape ENGO participation. We empirically explore this framework in the context of seven regional fisheries management organizations. A dataset comprising yearly fish stock-level data on participation, institutional, and ecological factors, for 1980-2014, was compiled for our quantitative inquiry into the determinants of ENGO participation. We find robust evidence that institutional change shapes ENGO participation, but not ecological factors related to target fish stock health. We discuss our findings against the backdrop of ongoing debates about NGOs in political science, and spell out broader implications for future research on NGOs in regional fisheries management organizations.

Atlantic bluefin tuna (Thunnus thynnus) are highly migratory fish with a contemporary range spanning the North Atlantic Ocean. Bluefin tuna populations have undergone severe decline and the status of the fish within each population remains uncertain. Improved biological knowledge, particularly of natural mortality and rates of mixing of the western (GOM) and eastern (Mediterranean) populations, is key to resolving the current status of the Atlantic bluefin tuna. We evaluated the potential for acoustic tags to yield empirical estimates of mortality and migration rates for long-lived, highly migratory species such as Atlantic bluefin tuna. Bluefin tuna tagged in the Gulf of St. Lawrence (GSL) foraging ground (2009–2016) exhibited high detection rates post release, with 91% crossing receiver lines one year post tagging, 61% detected after year two at large, with detections up to ~1700 days post deployment. Acoustic detections per individual fish ranged from 3 to 4759 receptions. A spatially-structured Bayesian mark recapture model was applied to the acoustic detection data for Atlantic bluefin tuna electronically tagged in the GSL to estimate the rate of instantaneous annual natural mortality. We report a median estimate of 0.10 yr−1 for this experiment. Our results demonstrate that acoustic tags can provide vital fisheries independent estimates for life history parameters critical for improving stock assessment models.

To understand the potential future impacts of climate change on marine fisheries science and management, it is useful to examine how and why management of fisheries for highly migratory fish species has or has not worked in the past, and whether we expect these trends to continue. Climate change will result in greater uncertainty in the projections of marine fish populations, and the structure of international fisheries management organizations will, to a great degree, determine their ability to adapt and effectively manage fish populations under their purview. I briefly describe the structure and function of national and international fisheries regulatory bodies and highlight several key structures that lead to effective management. I also examine the likelihood that effective governance structures can be applied to management bodies where they are currently lacking. Finally, I identify potential ways forward in instances where it seems unlikely to improve current management bodies.

(1) Search string to identify papers related to migratory connectivity in the ocean, (2) MiCO Species List, and (3) Weblinks for online resources

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.

As anthropogenic climate change increases the temperatures of the world's oceans, the survival rates, spatial distributions, and phenology of marine species are affected. Additionally, cyclical climate oscillations, such as the North Atlantic Oscillation (NAO), influence species presences throughout the Atlantic Basin. We evaluate the potential effects of local habitat variability on the nearshore presence of 7 commercial fish species along the South Atlantic Bight. Employing random forest models, we assess the relationships between historical observed presence and bottom temperature (BT), salinity, benthic habitat structure, and the NAO. Our results suggest that for some species, the influence of BT on species nearshore presence depends on the phase of the NAO. Thus, the statistical responses of some species to changing ocean temperatures will largely depend on the phase of the NAO.

Tiger sharks, Galeocerdo cuvier, are apex predators that may structure marine communities through predation. Despite a large number of studies in other areas such as the Pacific Ocean, there are no quantitative data on the diet of tiger sharks in the northwest Atlantic Ocean and Gulf of Mexico. Diet was assessed from 169 tiger sharks by life stage, area, and environmental factors. Fifteen prey groups were identified, with teleosts, molluscs, birds, cephalopods, and reptiles being the predominant prey categories. There was an ontogenetic shift in diet, prey size and diversity. Molluscs were the most common prey in smaller sharks, while teleosts and reptiles became more important in the diet of larger sharks. Dietary overlap was significant by area (Gulf of Mexico vs Atlantic Ocean) and among all life stages except for young-of-the-year and adult tiger sharks. Juvenile tiger sharks also demonstrated selective feeding by targeting gastropod feet over ingesting the entire animal. While results were similar to feeding studies conducted on tiger sharks in other ocean basins, an understanding of area-specific trophic interactions is necessary to inform decision support tools for ecosystem-based approaches to management.

While ecologists have long recognized the influence of spatial resolution on species distribution models (SDMs), they have given relatively little attention to the influence of temporal resolution. Considering temporal resolutions is critical in distribution modelling of highly mobile marine animals, as they interact with dynamic oceanographic processes that vary at time‐scales from seconds to decades. We guide ecologists in selecting temporal resolutions that best match ecological questions and ecosystems, and managers in applying these models. We group the temporal resolutions of environmental variables used in SDM s into three classes: instantaneous, contemporaneous and climatological. We posit that animal associations with fine‐scale and ephemeral features are best modelled with instantaneous covariates. Associations with large scale and persistent oceanographic features are best modelled with climatological covariates. Associations with mesoscale features are best modelled with instantaneous or contemporaneous covariates if ephemeral processes are present or interannual variability occurs, and climatological covariates if seasonal processes dominate and interannual variability is weak.

Understanding and predicting the responses of wide‐ranging marine predators such as cetaceans, seabirds, sharks, turtles, pinnipeds and large migratory fish to dynamic oceanographic conditions requires habitat‐based models that can sufficiently capture their environmental preferences. Marine ecosystems are inherently dynamic, and animal–environment interactions are known to occur over multiple, nested spatial and temporal scales. The spatial resolution and temporal averaging of environmental data layers are therefore key considerations in modelling the environmental determinants of habitat selection. The utility of environmental data contemporaneous to animal presence or movement (e.g. daily, weekly), versus synoptic products (monthly, seasonal, climatological) is currently debated, as are the trade‐offs between near real‐time, high resolution and composite (i.e. synoptic, cloud‐free) data fields.Using movement simulations with built‐in environmental preferences in combination with both modelled and remotely‐sensed (ROMS, MODIS‐Aqua) sea surface temperature (SST) fields, we explore the effects of spatial and temporal resolution (3–111 km, daily–climatological) in predictive habitat models. Results indicate that models fitted using seasonal or climatological data fields can introduce bias in presence‐availability designs based upon animal movement datasets, particularly in highly dynamic oceanographic domains. These effects were pronounced where models were constructed using seasonal or climatological fields of coarse (> 0.25 degree) spatial resolution. However, cloud obstruction can lead to significant information loss in remotely‐sensed data fields. We found that model accuracy decreased substantially above 70% data loss. In cloudy regions, weekly or monthly environmental data fields may therefore be preferable. These findings have important implications for marine resource management, particularly in identifying key habitats for populations of conservation concern, and in forecasting climate‐mediated ecosystem changes.