ArticlePublisher preview available

Global spatial risk assessment of sharks under the footprint of fisheries

August 2019
Nature 572(7770):1

DOI:10.1038/s41586-019-1444-4

Authors:

Nicolas E Humphries

Marine Biological Association of the UK

Ana Sofia Couto

Biomathematics and Statistics Scotland

Marisa Vedor

University of Porto

Show all 153 authorsHide

Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management.

The locations of shark tag deployment sites in relation to shark space-use hotspots, ocean currents, physical features and fishing areas a, Red circles denote the locations in which satellite transmitters were attached and sharks released, and blue squares in the eastern Pacific Ocean denote the annual median deployment locations of tags by the TOPP program¹¹. Shark space-use hotspots are shown as the 75th (blue dotted lines) and 90th percentiles (red dotted lines) of the mean monthly relative density of estimated shark locations within 1° × 1° grid cells given in Fig. 2a. b, c, Schematic maps of major ocean currents (b) and physical features overlaid on FAO fishing areas (c). Coloured arrows in b denote the thermal regime of currents, with warmer colours indicating higher water temperatures. CGFZ, Charlie Gibbs Fracture Zone; GBR, Great Barrier Reef; PNG, Papua New Guinea.

…

Seasonal shifts in sharks, longline-fishing vessels and patterns of overlap with fishing effort a–h, Mean quarterly relative spatial density of sharks (left), longline-fishing effort (in days) (middle) and mean FEI per grid cell (the fishing effort to which sharks were exposed in overlapped areas) (right) for blue sharks in the North Atlantic Ocean in December–February (a), March–May (b), June–August (c) and September–November (d), and for shortfin mako sharks in the North Atlantic Ocean in December–February (e), March–May (f), June–August (g) and September–November (h).

…

Spatial distribution of fishing vessels and overlap with sharks a, Distribution of the fishing effort of AIS-tracked vessels (mean annual days spent per grid cell) between 2012 and 2016 (Methods). b, Distribution of the mean monthly overlap and level of the fishing effort for all vessels (in days) to which sharks were exposed in overlapping areas, for all species, within 1° × 1° grid cells (Methods). Spatial overlap hotspots were defined as 1° × 1° grid cells with ≥75th percentile of mean FEI. Note that the overlap pattern of sharks and all mapped AIS-equipped fishing vessels is similar to that determined for sharks and longline-fishing vessels in Fig. 2c. c, Distribution of the fishing effort of AIS-equipped purse-seine vessels, using mean annual days spent per grid cell between 2012 and 2016 (Methods). d, Distribution of the mean monthly overlap and level of fishing effort of purse-seine vessel (in days) to which sharks were exposed in overlapping areas, for all species, within 1° × 1° grid cells (Methods). Spatial overlap hotspots were defined as 1° × 1° grid cells with ≥75th percentile of mean FEI.

…

Environmental modelling results Estimated relationships between mean monthly relative density of all sharks (top) and fishing effort of all AIS-equipped fishing vessels (middle) and longline-fishing vessels only (bottom), with all environmental variables in the highest-ranked model (model 1) of the GAM tested. The third column shows the interaction results between the two variables described in the first and second columns. Asterisks indicate the significance level for each smooth term included in the GAM; ***P < 0.001.

…

Effect of grid-cell size on risk-exposure patterns of sharks to longline fisheries a–d, North Atlantic Ocean (a), east Pacific Ocean (b), southwest Indian Ocean (c) and Oceania (d). Note that, regardless of the grid-cell size at which the individual-species mean spatial overlap and FEI were calculated, the species that occur in the highest-(red) and the lowest-risk zones (green) remain notably conserved, which indicates a general pattern that is not dependent on the scale at which these data were analysed. Shark-species identification codes corresponding to marker colours are given in Fig. 3. In addition, for the North Atlantic (a), hammerhead sharks (Sphyrna spp.) are represented by a black circle and oceanic whitetip sharks (C. longimanus) by a light blue circle; for the eastern Pacific Ocean (b), the salmon shark (L. ditropis) is represented by a light orange circle. Error bars are ± 1 s.d. An additional comparison of 2° × 2° with 1° × 1° grid-cell size is given in Supplementary Fig. 4.

…

Figures - available from: Nature

This content is subject to copyright. Terms and conditions apply.

A preview of this full-text is provided by Springer Nature.
Learn more

Preview content only

Content available from Nature

This content is subject to copyright. Terms and conditions apply.

ARTICLE https://doi.org/10.1038/s41586-019-1444-4

Global spatial risk assessment of sharks

under the footprint of fisheries

Effective ocean management and the conservation of highly migratory species depend on resolving the overlap between

animal movements and distributions, and fishing effort. However, this information is lacking at a global scale. Here we

show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fleets,

that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space-use

hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines

(up to 76% and 64%, respectively), and were also associated with significant increases in fishing effort. We conclude that

pelagic sharks have limited spatial refuge from current levels of fishing effort in marine areas beyond national jurisdictions

(the high seas). Our results demonstrate an urgent need for conservation and management measures at high-seas hotspots

of shark space use, and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool

for near-real-time, dynamic management.

Industrialized fishing is a major source of mortality for large marine

animals (marine megafauna)

1–6

. Humans have hunted megafauna in

the open ocean for at least 42,000 years7, but international fishing fleets

that target large, epipelagic fishes did not spread into the high seas until

the 1950s8. Prior to this, the high seas constituted a spatial refuge that

was largely free from exploitation, as fishing pressure was concentrated

on continental shelves

3,8

. Pelagic sharks are among the widest-ranging

vertebrates, with some species exhibiting annual migrations on

the ocean-basin scale9, long term trans-ocean movements10 and/or

fine-scale site fidelity to preferred shelf and open ocean areas5,9,11.

These behaviours could cause extensive spatial overlap with different

fisheries that exploit regions ranging from coastal areas to the deep

ocean. On average, large pelagic sharks account for 52% of all of the

identified shark catch worldwide, from both shark-targeting fisheries

and as bycatch

. Regional declines in abundance of pelagic sharks have

previously been reported

13,14

, but it is unclear whether exposure to high

levels of fishing effort extends across ocean-wide population ranges and

overlaps areas of the high seas in which sharks are most abundant5,13.

The conservation of pelagic sharks—the management of which on

the high seas is currently limited

12,15,16

—would benefit greatly from a

clearer understanding of the spatial relationships between the habitats

of sharks and active fishing zones. However, obtaining unbiased esti-

mates of the distributions of sharks and fishing effort is complicated by

the fact that most data on pelagic sharks come from catch records and

other fishery-dependent sources4,15,16.

Here we provide a global estimate of the extent of overlap in the use

of space between sharks and industrial fisheries. This estimate is based

on analysis of the movements of pelagic sharks tagged with satellite

transmitters in the Atlantic, Indian and Pacific Oceans, together with

the movements of fishing vessels that are monitored globally by the

automatic identification system (AIS), which was developed as a vessel

safety and anti-collision system (Methods). Our study focuses on 23

species of large pelagic sharks that occupy oceanic and/or neritic hab-

itats, which span a broad distribution from cold–temperate to tropical

waters (Supplementary Table1). All of these species face some level

of fishing pressure from coastal, shelf and/or high-seas fisheries: the

International Union for the Conservation of Nature (IUCN) Red List

assesses almost two-thirds of these species as being endangered (26%)

or vulnerable (39%), and a further quarter as near-threatened (26%)

(Supplementary Table2). Although regional-fisheries management

organizations are tasked with the management of sharks in the high

seas, little or no management is in place for most species3,5,12–18.

Movement patterns of sharks and fishing vessels

The 11 shark species (or taxa groups) that accounted for 96% of the

1,804 satellite tags that were deployed are among the largest of shark

species: blue sharks (Prionace glauca); shortfin mako sharks (Isurus

oxyrinchus); tiger sharks (Galeocerdo cuvier); salmon sharks (Lamna

ditropis); whale sharks (Rhincodon typus); white sharks (Carcharodon

carcharias); oceanic whitetip sharks (Carcharhinus longimanus); por-

beagle sharks (Lamna nasus); silky sharks (Carcharhinus falciformis);

bull sharks (Carcharhinus leucas); and hammerhead sharks (Sphyrna

spp.) (Supplementary Tables3−5). Movement patterns indicated that

multiple species aggregated within the same major oceanographic

features (Fig.1), such as the Gulf Stream (blue sharks, shortfin mako

sharks, tiger sharks, white sharks and porbeagle sharks), the California

Current (blue sharks, shortfin mako sharks, white sharks and salmon

sharks) and the East Australian Current (blue sharks, shortfin mako

sharks, tiger sharks, white sharks and porbeagle sharks), (Extended

Data Fig.1; see ‘Supplementary results and discussion, section2.1’

intheSupplementary Information). The global relative density map

(Fig.2a) reveals distribution patterns of pelagic sharks and the locations

of space-use hotspots (defined here as areas with≥75th percentile of

weighted daily location density) (Methods). Major space-use hotspots

of tracked pelagic sharks in the Atlantic Ocean were in the Gulf Stream

and its western approaches, the Caribbean Sea, the Gulf of Mexico

and around oceanic islands such as the Azores (Fig.2a, Supplementary

Table6). In the Indian Ocean, space-use hotspots were evident in the

Agulhas Current, Mozambique Channel, the South Australian Basin

and northwest Australia, and in the Pacific Ocean, space-use hotspots

were in the California Current, Galapagos Islands and around New

Zealand. Although, as expected, tagging sites occurred in some space-

use hotspots (as tagging rates are inherently higher in hotspots), we also

identified space-use hotspots in which no tagging sites occurred in the

North Atlantic Ocean (outer Gulf Stream, Charlie Gibbs Fracture Zone,

western European shelf edge and the Bay of Biscay), the Indian Ocean

(southern Madagascar, the Crozet and Amsterdam Islands, and the

South Australian Basin) and the Pacific Ocean (Alaska Current, outer

California Current, the white shark ‘café’ area, halfway between Baja

California and Hawaii11, North Equatorial Current, Clipperton Island

A list of authors and their affiliations appears in the online version of the paper.

22 AUGUST 2019 | VOL 572 | NATURE | 461

Content courtesy of Springer Nature, terms of use apply. Rights reserved

Working Group on North Atlantic Salmon (WGNAS)

Technical Report

Full-text available

May 2023

WGNAS met to consider the status of and threats to Atlantic salmon in the North Atlantic Salmon Conservation Organisation (NASCO) commission areas: West Greenland (WGC), North American (NAC), and Northeast Atlantic (NEAC). Many updates are provided for 2021 and 2022 as WGNAS was not able to address all terms of reference (ToRs) in 2022. Information on the catch and exploitation, including salmon caught and released, and nominal harvest, as well as tagged and marked fish releases are provided by country and jurisdiction. Emerging threats are presented, including the first report of Infectious Salmon Anaemia (ISA) in Iceland, red skin disease in Europe, and Norway is evaluating new offshore farming sites. New scientific advancements reported on include non-lethal Gyrodactylus treatment, homewater return rate estimation methods, and genetic tools to understand the reproductive success of salmon that have been caught and released. ICES did not conduct a full assessment for salmon in NEAC because the Framework of Indicators (FWI) did not indicate that the forecast estimates of abundance for the four NEAC stock complexes had been underestimated. WGNAS was asked to provide information on three key issues in 2023, namely: 1. the causes of variability in return rates between rivers within regions of the North Atlantic, concluding that factors at river-specific, regional and oceanic scales interact to affect marine survival rates and maturation schedules, and it is unlikely that a single factor alone accounts for temporal variations and the decline of wild salmon in the North Atlantic; 2. the current state of knowledge on freshwater and marine predation by cormorants, concluding that cormorants can have substantial impacts on salmon abundance in areas where cormorant populations have increased or declines in other cormorant prey abundance have occurred, an issue of special concern where salmon populations are already threatened or endangered; and, 3. an evaluation of the risk of salmon bycatch occurring in pelagic and coastal fisheries, and effectiveness and adequacy of current bycatch monitoring programmes, concluding that ICES ability to evaluate the risk of bycatch is limited because few pelagic fisheries are screened for bycatch and screening covers small proportions of catch. To advance our capacity to evaluate such risks, a series of data deficiencies, monitoring needs and research requirements are identified. Looking forward, a Bayesian life-cycle assessment model and data inputs were discussed in connection with the 2023 benchmark.

Shortfalls in tracking data available to inform North American migratory bird conservation

Article

Full-text available

Sep 2023
BIOL CONSERV

Animal tracking has become an effective way to identify where and when migratory species encounter threats throughout their annual cycle. Yet, untracked or poorly tracked species and undiscoverable or inaccessible data for the species that have been tracked mean that gaps in the knowledge of where and when species occur are still an issue for conservation. These gaps in knowledge of species movements have been termed the "movement shortfall". Here, we quantify the movement shortfall for North American migratory birds by comprehensively reviewing full annual cycle tracking data and identifying gaps and biases in how, where, and what species are tracked with electronic tracking devices. We found 30 species for which tracking is not feasible given body size constraints, no data for 291 trackable species, and restricted or reduced data accessibility for an additional 59 species. Thus, despite the ability to track most species, the movement shortfall remains a constraint to informing conservation strategies for 56 % of North American migratory bird species. The number increases to 65 % when considering species with restricted or reduced data accessibility, further limiting access to this information. Moreover, 23 % of the tracking data stems from low precision tracking technologies reducing the implementation and effectiveness to conservation actions. A lack of species and population data hinders conservation and biases management decisions, ultimately making inefficient use of conservation resources. We encourage researchers to consider these gaps in their decisions about future tracking efforts, conservation management, and data archiving practices.

Best practices for catch-and-release shark angling: current scientific understanding and future research

Article

Full-text available

Nov 2023
FISH RES

In recent decades, the abundance of sharks in the world's oceans has decreased due to overexploitation by commercial fisheries. Over this same period, sharks have been increasingly targeted for sport by recreational anglers. "Catch-and-release" (C&R) angling, where sharks are released alive after capture, has been proposed, and in some situations, mandated as a conservation measure in recreational fisheries. In C&R fisheries, anglers are encouraged to follow best practices, each with the goal of maximising post-release survivorship (PRS) of angled fish. Here for sharks, we review C&R global best practices and the science underpinning them. Despite shark C&R fishing being practiced globally, peer-reviewed research into post-release survivorship is limited to just twelve studies for eight species (Lamniformes, n = 3; Carcharhiniformes, n = 5). PRS in studies ranged from 56% to 100%. Identifying causes for decreased PRS (i.e. mortality) was challenging for studies due to low sample sizes. Of the factors investigated, candidate best practices included: (1) using non-stainless steel circle hooks, (2) not removing sharks from the water, (3) reviving sharks prior to release, and (4) minimising time spent freeing the shark by removing the hook or cutting the line. With the conservation status of many sharks declining, more research is needed to strengthen the scientific basis for these practices to ensure that PRS in C&R is maximised.

Stakeholders' perceptions of the conservation and management of elasmobranchs in South Africa

Article

Sep 2023
MAR POLICY

Global shark populations are in serious decline, especially due to overexploitation through fisheries, whose impact is often increased by a lack of proper management regulations and enforcement. South Africa’s population of chondrichthyan fauna is one of the most diverse in the world, with high rates of endemic and imperiled elasmobranch species. South Africa has been lauded as a global leader in shark conservation through progressive management legislation, such as the 2013 National Plan of Action for the Conservation and Management of Sharks (NPOA-Sharks I). However, South Africa’s shark populations have continued to decline. This study aimed to survey stakeholders’ (students, academics, government representatives, conservationists, recreational anglers, commercial fishers, and tourism-related stakeholders) perspectives on the efficacy of NPOA-Sharks I in managing and enforcing fisheries regulations and to advise the 2022 NPOA-Sharks II approach concerning the conservation of South African elasmobranchs. A total of 89 stakeholders participated in an online questionnaire survey launched in 2021. Most stakeholders viewed the NPOA-Sharks I as somewhat appropriate, South Africa’s current exploitation of shark stocks as unsustainable and management and enforcement of regulations as inadequate. Commercial fishing and lack of enforcement were ranked as the two most pressing issues facing South Africa’s sharks. Similarly, the expert review panel found limited progress (<50%) made in the implementation of the NPOA-Sharks I concerning regulatory tools and sustainable management and called for improved monitoring, surveillance and enforcement of compliance regulations across fisheries as one of the top recommendations for immediate implementation in NPOA-Sharks II. However, the majority of action items under the “Sustainable Management” issue cluster in NPOA-Sharks II suggest a reassessment or reestablishment of existing regulations or the development of new regulatory tools with few specifics provided, reflective of a disconnect between what the lead government agency responsible for the management of South Africa’s sharks, the Department of Forestry, Fisheries and the Environment (DFFE), perceives to be effective and what stakeholders experience concerning shark conservation in South Africa. What was perceived by the national management agency as effective concerning shark conservation in South Africa was not necessarily experienced as such by the stakeholders. There is a need for increased collaboration among stakeholders and significant improvements in the practical management of South African fisheries for shark conservation, which is now also suggested in the NPOA-Sharks II.

Persistent transboundary movements of threatened sharks highlight the importance of cooperative management for effective conservation

Article

Jan 2023

Tracking oceanic fishes

Chapter

Jan 2023

Effects of climate change and variability on large pelagic fish in the Northwest Atlantic Ocean: implications for improving climate resilient management for pelagic longline fisheries

Article

Full-text available

Sep 2023

Climate change influences marine environmental conditions and is projected to increase future environmental variability. In the North Atlantic, such changes will affect the behavior and spatiotemporal distributions of large pelagic fish species (i.e., tunas, billfishes, and sharks). Generally, studies on these species have focused on specific climate-induced changes in abiotic factors separately (e.g., water temperature) and on the projection of shifts in species abundance and distribution based on these changes. In this review, we consider the latest research on spatiotemporal effects of climate-induced environmental changes to HMS' life history, ecology, physiology, distribution, and habitat selection, and describe how the complex interplay between climate-induced changes in biotic and abiotic factors, including fishing, drives changes in species productivity and distribution in the Northwest Atlantic. This information is used to provide a baseline for investigating implications for management of pelagic longline fisheries and to identify knowledge gaps in this region. Warmer, less oxygenated waters may result in higher post-release mortality in bycatch species. Changes in climate variability will likely continue to alter the dynamics of oceanographic processes regulating species behavior and distribution, as well as fishery dynamics, creating challenges for fishery management. Stock assessments need to account for climate-induced changes in species abundance through the integration of species-specific responses to climate variability. Climate-induced changes will likely result in misalignment between Frontiers in Marine Science

Spatial overlap between South American fur seal foraging effort and commercial trawl fisheries in the Falkland Islands

Article

Full-text available

Aug 2023

Regional (south‐eastern Pacific Ocean) population genetics and global phylogeography of two endangered highly migratory pelagic sharks, the blue shark Prionace glauca and shortfin mako Isurus oxyrinchus

Article

Jul 2023

The blue shark Prionace glauca and the shortfin mako Isurus oxyrinchus are two large and highly migratory sharks inhabiting temperate and tropical waters worldwide that are heavily targeted by artisanal and industrial fisheries. The International Union for Nature Conservation classifies the blue shark and shortfin mako as ‘Near Threatened’ and ‘Vulnerable’, respectively, in the Nature Red List of Threatened Species v. 2019‐2. This study examined the population genetics of the shortfin mako and blue sharks at a regional (south‐eastern Pacific Ocean) and global scale. The null hypothesis of no genetic discontinuities among ocean basins and/or between hemispheres was tested using two mitochondrial markers suitable for population genetics inference in these species: the non‐coding control region and the protein‐coding gene cytochrome c oxidase I in I. oxyrinchus , and the control region and cytochrome b in P. glauca . Spatial genetic analyses suggested a single and two genetic clusters co‐occurring along the south‐eastern Pacific Ocean in the shortfin mako and blue shark, respectively. Phylogeographic analyses, migration estimates, haplotype networks and AMOVAs demonstrated that the two species exhibit an overall pattern of high genetic connectivity among hemispheres and across ocean basins with a signature of shallow genetic structuring worldwide. This study has generated valuable information for the management and conservation of heavily exploited sharks and highlights the need for additional inclusive research programmes assessing inter‐regional genomic discontinuities using more statistically powerful genetic markers to determine with precision population genetic discontinuities (if any) in these and other highly migratory sharks.

Quantifying longline bycatch mortality for pelagic sharks in western Pacific shark sanctuaries

Article

Full-text available

Aug 2023

Marine protected areas are increasingly touted for their role in conserving large marine predators such as sharks, but their efficacy is debated. Seventeen "shark sanctuaries" have been established globally, but longline fishing continues within many such jurisdictions, leading to unknown levels of bycatch mortality levels. Using public data from Global Fishing Watch and Regional Fisheries Management Organizations, we quantified longline fishing within eight shark sanctuaries and estimated pelagic shark catch and mortality for seven pelagic shark species. Sanctuary mortality ranged from 600 individuals (Samoa) to 36,256 individuals (Federated States of Micronesia), equivalent to ~5% of hypothesized sustainable levels for blue sharks to ~40% for silky sharks, with high mortality levels in the Federated States of Micronesia, Palau, and the Marshall Islands. Unsustainable mortality rates were exceeded for silky sharks in two sanctuaries, highlighting a need for additional stock assessments and implementation of bycatch reduction measures. Big data integration workflows represent a transformative tool in fisheries management, particularly for data-poor species.

Response to Comment on “Tracking the global footprint of fisheries”

Article

Full-text available

Aug 2018

Amoroso et al. demonstrate the power of our data by estimating the high-resolution trawling footprint on seafloor habitat. Yet we argue that a coarser grid is required to understand full ecosystem impacts. Vessel tracking data allow us to estimate the footprint of human activities across a variety of scales, and the proper scale depends on the specific impact being investigated.

Far from home: Distance patterns of global fishing fleets

Article

Full-text available

Aug 2018

Postwar growth of industrial fisheries catch to its peak in 1996 was driven by increasing fleet capacity and geographical expansion. An investigation of the latter, using spatially allocated reconstructed catch data to quantify “mean distance to fishing grounds,” found global trends to be dominated by the expansion histories of a small number of distant-water fishing countries. While most countries fished largely in local waters, Taiwan, South Korea, Spain, and China rapidly increased their mean distance to fishing grounds by 2000 to 4000 km between 1950 and 2014. Others, including Japan and the former USSR, expanded in the postwar decades but then retrenched from the mid-1970s, as access to other countries’ waters became increasingly restricted with the advent of exclusive economic zones formalized in the 1982 United Nations Convention on the Law of the Sea. Since 1950, heavily subsidized fleets have increased the total fished area from 60% to more than 90% of the world’s oceans, doubling the average distance traveled from home ports but catching only one-third of the historical amount per kilometer traveled. Catch per unit area has declined by 22% since the mid-1990s, as fleets approach the limits of geographical expansion. Allowing these trends to continue threatens the bioeconomic sustainability of fisheries globally.

A simple function for full-subsets multiple regression in ecology with R

Article

Full-text available

Jun 2018

Full-subsets information theoretic approaches are becoming an increasingly popular tool for exploring predictive power and variable importance where a wide range of candidate predictors are being considered. Here, we describe a simple function in the statistical programming language R that can be used to construct, fit, and compare a complete model set of possible ecological or environmental predictors, given a re- sponse variable of interest and a starting generalized additive (mixed) model fit. Main advantages include not requiring a complete model to be fit as the starting point for candidate model set construction (meaning that a greater number of predictors can potentially be explored than might be available through functions such as dredge); model sets that include interactions between factors and continuous nonlinear pre- dictors; and automatic removal of models with correlated predictors (based on a user defined criterion for exclusion). The function takes continuous predictors, which are fitted using smoothers via either gam, gamm (mgcv) or gamm4, as well as factor vari- ables which are included on their own or as two- level interaction terms within the gam smooth (via use of the “by” argument), or with themselves. The function allows any model to be constructed and used as a null model, and takes a range of arguments that allow control over the model set being constructed, including specifying cyclic and linear continuous predictors, specification of the smoothing algorithm used, and the maximum complexity allowed for smooth terms. The use of the function is dem- onstrated via case studies that highlight how appropriate model sets can be easily constructed and the broader utility of the approach for exploratory ecology.

Fisheries bycatch risk to marine megafauna is intensified in Lagrangian coherent structures

Article

Full-text available

Jun 2018

Significance Marine capture fisheries provide a valuable source of protein and are economically important in coastal communities. However, fisheries sustainability is impacted by incidental capture of nontarget species (bycatch), which remains a major global threat to marine megafauna such as sharks, sea turtles, seals, cetaceans, and seabirds. Understanding where and when bycatch events take place can guide fisheries sustainability solutions. Here, we model how dynamic structures in the ocean such as fronts and eddies influence fisheries effort, catch, and bycatch likelihood. We find that bycatch of a diverse range of species is more likely in attracting Lagrangian coherent structures, in which water masses meet and aggregate prey, predators, and fishers into hotspots of risk.

The economics of fishing the high seas

Article

Full-text available

Jun 2018

While the ecological impacts of fishing the waters beyond national jurisdiction (the “high seas”) have been widely studied, the economic rationale is more difficult to ascertain because of scarce data on the costs and revenues of the fleets that fish there. Newly compiled satellite data and machine learning now allow us to track individual fishing vessels on the high seas in near real time. These technological advances help us quantify high-seas fishing effort, costs, and benefits, and assess whether, where, and when high-seas fishing makes economic sense. We characterize the global high-seas fishing fleet and report the economic benefits of fishing the high seas globally, nationally, and at the scale of individual fleets. Our results suggest that fishing at the current scale is enabled by large government subsidies, without which as much as 54% of the present high-seas fishing grounds would be unprofitable at current fishing rates. The patterns of fishing profitability vary widely between countries, types of fishing, and distance to port. Deep-sea bottom trawling often produces net economic benefits only thanks to subsidies, and much fishing by the world’s largest fishing fleets would largely be unprofitable without subsidies and low labor costs. These results support recent calls for subsidy and fishery management reforms on the high seas.

Longest recorded trans-Pacific migration of a whale shark (Rhincodon typus)

Article

Full-text available

Dec 2018

Abstract Whale sharks (Rinchodon typus) are found in shallow coastal and deep waters of tropical and warm temperate seas. Population genetic studies indicate high connectivity among populations, and an Indo-Pacific meta-population has been suggested with potential migrations among some ocean basins. Here, we present the satellite track of a trans-Pacific migration of a female whale shark, which we tagged at Coiba Island (Panama), and which travelled over 20,000 km from the Tropical Eastern Pacific (Panama) to the western Indo-Pacific (Mariana Trench) in 841 d, primarily via the North Equatorial Current. This finding illustrates the migratory pathway between two ocean basins and potential passageway to reach the Philippine Sea into the South China Sea.

Addressing Criticisms of Large-Scale Marine Protected Areas

Article

Full-text available

Apr 2018

Designated large-scale marine protected areas (LSMPAs, 100,000 or more square kilometers) constitute over two-thirds of the approximately 6.6% of the ocean and approximately 14.5% of the exclusive economic zones within marine protected areas. Although LSMPAs have received support among scientists and conservation bodies for wilderness protection, regional ecological connectivity, and improving resilience to climate change, there are also concerns. We identified 10 common criticisms of LSMPAs along three themes: (1) placement, governance, and management; (2) political expediency; and (3) social-ecological value and cost. Through critical evaluation of scientific evidence, we discuss the value, achievements, challenges, and potential of LSMPAs in these arenas. We conclude that although some criticisms are valid and need addressing, none pertain exclusively to LSMPAs, and many involve challenges ubiquitous in management. We argue that LSMPAs are an important component of a diversified management portfolio that tempers potential losses, hedges against uncertainty, and enhances the probability of achieving sustainably managed oceans.

Translating Marine Animal Tracking Data into Conservation Policy and Management

Article

Mar 2019
TRENDS ECOL EVOL

There have been efforts around the globe to track individuals of many marine species and assess their movements and distribution, with the putative goal of supporting their conservation and management. Determining whether, and how, tracking data have been successfully applied to address real-world conservation issues is, however, difficult. Here, we compile a broad range of case studies from diverse marine taxa to show how tracking data have helped inform conservation policy and management, including reductions in fisheries bycatch and vessel strikes, and the design and administration of marine protected areas and important habitats. Using these examples, we highlight pathways through which the past and future investment in collecting animal tracking data might be better used to achieve tangible conservation benefits.

Comment on “Tracking the global footprint of fisheries”

Article

Aug 2018

Kroodsma et al. (Reports, 23 February 2018, p. 904) mapped the global footprint of fisheries. Their estimates of footprint and resulting contrasts between the scale of fishing and agriculture are an artifact of the spatial scale of analysis. Reanalyses of their global (all vessels) and regional (trawling) data at higher resolution reduced footprint estimates by factors of >10 and >5, respectively.

A comparison of VMS and AIS data: The effect of data coverage and vessel position recording frequency on estimates of fishing footprints

Article

May 2018

Understanding the distribution of fishing activity is fundamental to quantifying its impact on the seabed. Vessel monitoring system (VMS) data provides a means to understand the footprint (extent and intensity) of fishing activity. Automatic Identification System (AIS) data could offer a higher resolution alternative to VMS data, but differences in coverage and interpretation need to be better understood. VMS and AIS data were compared for individual scallop fishing vessels. There were substantial gaps in the AIS data coverage; AIS data only captured 26% of the time spent fishing compared to VMS data. The amount of missing data varied substantially between vessels (45-99% of each individuals' AIS data were missing). A cubic Hermite spline interpolation of VMS data provided the greatest similarity between VMS and AIS data. But the scale at which the data were analysed (size of the grid cells) had the greatest influence on estimates of fishing footprints. The present gaps in coverage of AIS may make it inappropriate for absolute estimates of fishing activity. VMS already provides a means of collecting more complete fishing position data, shielded from public view. Hence, there is an incentive to increase the VMS poll frequency to calculate more accurate fishing footprints. © International Council for the Exploration of the Sea 2017. All rights reserved.