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Hatch JM, Murray KT, Patel S, Smolowitz R, Haas HL. Evaluating simple measures of spatial-temporal overlap as a proxy for encounter risk between a protected species and commercial fishery. FRONTIERS IN CONSERVATION SCIENCE 2023. [DOI: 10.3389/fcosc.2023.1118418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023] Open
Abstract
Spatial and temporal assessments of overlap are becoming increasingly popular as indicators of encounter risk. The overlap in distributions between protected species and commercial fishing effort is of interest for reducing bycatch. We explored overlap between the U.S. Atlantic sea scallop fishery and loggerhead turtles (Caretta caretta) using 2 metrics, and we assessed the ability of one of those metrics to track estimated fishery interactions over time. Moderate overlap occurred between June - September; mild overlap in the spring (May) and fall (October - November); and relatively little overlap from December to April. Qualitatively, there appeared to be some correspondence between the overlap values averaged across months for each calendar year and published annual loggerhead interaction estimates with fisheries, but the predictive performance of the overlap metric was low. When data on the relative distributions of commercial fishing effort and protected species are available, simple measures of spatial and temporal overlap can provide a quick and cost-effective way to identify when and where bycatch is likely to occur. In this case study, however, overlap was limited in helping to understand the relative susceptibility of protected species to commercial fishing (i.e., magnitude of interactions). We therefore caution against using overlap as a meaningful predictor of absolute risk unless there is direct evidence to suggest a relationship.
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Liang D, Bailey H, Hoover AL, Eckert S, Zarate P, Alfaro‐Shigueto J, Mangel JC, de Paz Campos N, Davila JQ, Barturen DS, Rguez‐Baron JM, Fahy C, Rocafuerte A, Veelenturf C, Abrego M, Shillinger GL. Integrating telemetry and point observations to inform management and conservation of migratory marine species. Ecosphere 2023. [DOI: 10.1002/ecs2.4375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Dong Liang
- Chesapeake Biological Laboratory University of Maryland Center for Environmental Science Solomons Maryland USA
| | - Helen Bailey
- Chesapeake Biological Laboratory University of Maryland Center for Environmental Science Solomons Maryland USA
| | | | - Scott Eckert
- Department of Biology and Natural Resources Principia College Elsah Illinois USA
- Wider Caribbean Sea Turtle Conservation Network (WIDECAST) Godfrey Illinois USA
| | - Patricia Zarate
- Instituto de Fomento Pesquero Valparaíso Chile
- MigraMar Bodega Bay California USA
| | - Joanna Alfaro‐Shigueto
- ProDelphinus Lima Peru
- Carrera de Biologia Marina, Universidad Cientifica del Sur Lima Peru
- Marine Turtle Research Group, Centre for Ecology and Conservation University of Exeter Penryn UK
| | - Jeffrey C. Mangel
- ProDelphinus Lima Peru
- Marine Turtle Research Group, Centre for Ecology and Conservation University of Exeter Penryn UK
| | | | - Javier Quinones Davila
- Oficina de Investigaciones en Depredadores Superiores Instituto del Mar del Perú, Chucuito Callao Peru
| | | | - Juan M. Rguez‐Baron
- JUSTSEA Foundation Bogotá Colombia
- Department of Biology and Marine Biology University of North Carolina Wilmington Wilmington North Carolina USA
| | - Christina Fahy
- Protected Resources Division West Coast Regional Office, National Marine Fisheries Service Long Beach California USA
| | | | | | - Marino Abrego
- Ministerio de Ambiente de Panamá Universidad Marítima Internacional de Panamá Panama City Panama
| | - George L. Shillinger
- Upwell, Heritage Harbor Complex Monterey California USA
- MigraMar Bodega Bay California USA
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Hines E, Ponnampalam LS, Junchompoo C, Peter C, Vu L, Huynh T, Caillat M, Johnson AF, Minton G, Lewison RL, Verutes GM. Getting to the bottom of bycatch: a GIS-based toolbox to assess the risk of marine mammal bycatch. ENDANGER SPECIES RES 2020. [DOI: 10.3354/esr01037] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Marine mammal bycatch poses a particular challenge in developing countries, where data to document bycatch and its effects are often lacking. Using the Bycatch Risk Assessment (ByRA) toolkit, based on InVEST open-source models, we chose 4 field sites in Southeast Asia with varying amounts of data on marine mammals and fishing occurrence: Trat province in the eastern Gulf of Thailand, the Sibu-Tinggi Islands and Kuching Bay, Malaysia, and Kien Giang Biosphere Reserve in southwestern Vietnam. These field sites have similar species of coastal marine mammals, small-scale and commercial fisheries, and support for research from universities and/or management. In Thailand and Kuching, results showed changing patterns of fishing and Irrawaddy dolphin Orcaella brevirostris habitat use across seasons, showing how bycatch risk could change throughout the year. Risk maps for dugongs Dugong dugon in peninsular Malaysia highlighted patterns of bycatch risk concentrated around a mainland fishing pier, and revealed high risk in a northern subregion. In Vietnam, first maps of bycatch risk for the Irrawaddy dolphin showed the highest risk driven by intensive use of gillnets and trawling gear. ByRA pinpointed areas of spatial and seasonal bycatch exposure, and estimated the consequence of bycatch on local species, providing managers with critical information on where to focus bycatch mitigation and meet new global standards for US Marine Mammal Protection Act and other international regulation (e.g. Official Journal of the European Union 2019; Regulation 2019/1241) compliance. The toolbox, a transferable open-source tool, can be used to guide fisheries management, marine mammal conservation, spatial planning, and further research.
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Affiliation(s)
- E Hines
- Estuary & Ocean Science Center, and Department of Geography & Environment, San Francisco State University, Tiburon, CA 94920, USA
| | - LS Ponnampalam
- The MareCet Research Organization, 5, Jalan USJ 12/1B 47630 Subang Jaya, Selangor, Malaysia
| | - C Junchompoo
- Department of Marine and Coastal Resources, Ministry of Natural Resources and Environment, Chaeng Watthana Road, Lak Si District, Bangkok 10210, Thailand
| | - C Peter
- Universiti Malaysia Sarawak, Jalan Datuk Mohammad Musa, 94300 Kota Samarahan, Sarawak, Malaysia
| | - L Vu
- Vietnam Marine Megafauna Network, Center for Biodiversity Conservation and Endangered Species, 24, Street No 13, Lakeview City, Ho Chi Minh City, Vietnam
| | - T Huynh
- Southern Institute of Ecology, Vietnam Academy of Science and Technology, 01 Mac Dinh Chi, Ben Nghe, District 1, Ho Chi Minh City, Vietnam
- Graduate School of Natural Science and Technology, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1164, Japan
| | - M Caillat
- Environmental Defense Fund, San Francisco, CA 94105, USA
| | - AF Johnson
- MarFishEco Fisheries Consultants, 67/6 Brunswick Street, Edinburgh EH7 5HT, UK
- The Lyell Centre, Institute of Life and Earth Sciences, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - G Minton
- Megaptera Marine Conservation, Laan van Rhemen van Rhemenshuizen 14, 2242 PT Wassenaar, The Netherlands
| | - RL Lewison
- Department of Biology, San Diego State University, CA 92182, USA
| | - GM Verutes
- Faculty of Political and Social Sciences, Universidade de Santiago de Compostela, Praza do Obradoiro, 0, 15705 Santiago de Compostela, A Coruña, Spain
- Campus Do*Mar, International Campus of Excellence, 36310 Vigo, Spain
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Ewbank AC, Sacristán C, Costa-Silva S, Antonelli M, Lorenço JR, Nogueira GA, Ebert MB, Kolesnikovas CKM, Catão-Dias JL. Postmortem findings in Magellanic penguins (Spheniscus magellanicus) caught in a drift gillnet. BMC Vet Res 2020; 16:153. [PMID: 32448250 PMCID: PMC7245875 DOI: 10.1186/s12917-020-02363-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 05/10/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Penguin interaction with gillnets has been extensively reported in the Atlantic and Pacific Oceans, and is considered a major conservation threat. Among penguin species, Magellanic penguins (Spheniscus magellanicus) are currently considered of great concern, particularly in Brazil, where they are highly susceptible to gillnet bycatch. Nevertheless, information about drowning-associated microscopic findings in penguins is limited. RESULTS We describe the anatomopathological findings of 20 Magellanic penguins that drowned after getting entangled in a drift gillnet while wintering along the Brazilian shelf and washed ashore still enmeshed in Santa Catarina, Brazil. All 20 birds (19 juveniles and 1 adult; 18 females and 2 males) were in good body condition. Major gross findings were abrasion, bruising, and local erythema and edema of the wings, multiorgan congestion, jugular vein engorgement, pulmonary edema and hemorrhage, splenomegaly and hepatomegaly, fluid in the trachea, serous bloody fluid in the lungs, gastrointestinal parasites (nematodes, cestodes and trematodes), and debris in the stomach. The most common histopathological findings were cerebral and pulmonary congestion, pulmonary edema, splenic histiocytosis, lymphoid splenic hyperplasia, acute splenitis, extramedullary hepatic hematopoiesis, and parasitic enteritis. Although unspecific, the observed multiorgan congestion and pulmonary edema are consistent with previous reports of drowning in birds and may be indicative of this process. CONCLUSIONS Drowning may be a challenging diagnosis (e.g., carcass decomposition, predation), but must be considered as a differential in all beach-cast seabird postmortem examinations. To the authors' knowledge this is the largest anatomopathological study based on microscopic examination in drowned penguins.
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Affiliation(s)
- Ana Carolina Ewbank
- Laboratory of Wildlife Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, SP, 05508-270, Brazil.
| | - Carlos Sacristán
- Laboratory of Wildlife Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, SP, 05508-270, Brazil
| | | | | | | | | | - Mariana B Ebert
- Laboratory of Wildlife Parasitology (LAPAS), Parasitology Department, Biosciences Institute, São Paulo State University (UNESP), Botucatu, SP, 18618-000, Brazil
| | | | - José Luiz Catão-Dias
- Laboratory of Wildlife Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, SP, 05508-270, Brazil
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Hurley I, Wringe BF, den Heyer CE, Shackell NL, Lotze HK. Spatiotemporal bycatch analysis of the Atlantic halibut (
Hippoglossus hippoglossus
) longline fishery survey indicates hotspots for species of conservation concern. CONSERVATION SCIENCE AND PRACTICE 2019. [DOI: 10.1111/csp2.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Isabelle Hurley
- Biology DepartmentDalhousie University Halifax Nova Scotia Canada
| | - Brendan F. Wringe
- Bedford Institute of OceanographyFisheries and Oceans Canada Dartmouth Nova Scotia Canada
| | - Cornelia E. den Heyer
- Bedford Institute of OceanographyFisheries and Oceans Canada Dartmouth Nova Scotia Canada
| | - Nancy L. Shackell
- Bedford Institute of OceanographyFisheries and Oceans Canada Dartmouth Nova Scotia Canada
| | - Heike K. Lotze
- Biology DepartmentDalhousie University Halifax Nova Scotia Canada
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Hurley I, Wringe BF, den Heyer CE, Shackell NL, Lotze HK. Spatiotemporal bycatch analysis of the Atlantic halibut ( Hippoglossus hippoglossus
) longline fishery survey indicates hotspots for species of conservation concern. CONSERVATION SCIENCE AND PRACTICE 2019. [DOI: 10.1002/csp2.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Isabelle Hurley
- Biology Department; Dalhousie University; Halifax Nova Scotia Canada
| | - Brendan F. Wringe
- Bedford Institute of Oceanography; Fisheries and Oceans Canada; Dartmouth Nova Scotia Canada
| | - Cornelia E. den Heyer
- Bedford Institute of Oceanography; Fisheries and Oceans Canada; Dartmouth Nova Scotia Canada
| | - Nancy L. Shackell
- Bedford Institute of Oceanography; Fisheries and Oceans Canada; Dartmouth Nova Scotia Canada
| | - Heike K. Lotze
- Biology Department; Dalhousie University; Halifax Nova Scotia Canada
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Fisheries bycatch risk to marine megafauna is intensified in Lagrangian coherent structures. Proc Natl Acad Sci U S A 2018; 115:7362-7367. [PMID: 29941592 DOI: 10.1073/pnas.1801270115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Incidental catch of nontarget species (bycatch) is a major barrier to ecological and economic sustainability in marine capture fisheries. Key to mitigating bycatch is an understanding of the habitat requirements of target and nontarget species and the influence of heterogeneity and variability in the dynamic marine environment. While patterns of overlap among marine capture fisheries and habitats of a taxonomically diverse range of marine vertebrates have been reported, a mechanistic understanding of the real-time physical drivers of bycatch events is lacking. Moving from describing patterns toward understanding processes, we apply a Lagrangian analysis to a high-resolution ocean model output to elucidate the fundamental mechanisms that drive fisheries interactions. We find that the likelihood of marine megafauna bycatch is intensified in attracting Lagrangian coherent structures associated with submesoscale and mesoscale filaments, fronts, and eddies. These results highlight how the real-time tracking of dynamic structures in the oceans can support fisheries sustainability and advance ecosystem-based management.
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Genovart M, Bécares J, Igual JM, Martínez-Abraín A, Escandell R, Sánchez A, Rodríguez B, Arcos JM, Oro D. Differential adult survival at close seabird colonies: The importance of spatial foraging segregation and bycatch risk during the breeding season. GLOBAL CHANGE BIOLOGY 2018; 24:1279-1290. [PMID: 29178374 DOI: 10.1111/gcb.13997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/20/2017] [Accepted: 11/07/2017] [Indexed: 05/10/2023]
Abstract
Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behavior. Scopoli's shearwater Calonectris diomedea is a long-lived seabird that experiences high bycatch rates in longline fisheries and strong population-level impacts due to this type of anthropogenic mortality. Analyzing a long-term dataset on individual monitoring, we compared adult survival (by means of multi-event capture-recapture models) among three close predator-free Mediterranean colonies of the species. Unexpectedly for a long-lived organism, adult survival varied among colonies. We explored potential causes of this differential survival by (1) measuring egg volume as a proxy of food availability and parental condition; (2) building a specific longline bycatch risk map for the species; and (3) assessing the distribution patterns of breeding birds from the three study colonies via GPS tracking. Egg volume was very similar between colonies over time, suggesting that environmental variability related to habitat foraging suitability was not the main cause of differential survival. On the other hand, differences in foraging movements among individuals from the three colonies expose them to differential mortality risk, which likely influenced the observed differences in adult survival. The overlap of information obtained by the generation of specific bycatch risk maps, the quantification of population demographic parameters, and the foraging spatial analysis should inform managers about differential sensitivity to the anthropogenic impact at mesoscale level and guide decisions depending on the spatial configuration of local populations. The approach would apply and should be considered in any species where foraging distribution is colony-specific and mortality risk varies spatially.
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Affiliation(s)
- Meritxell Genovart
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
| | - Juan Bécares
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | | | - Alejandro Martínez-Abraín
- Grupo de Investigación en Biología Evolutiva, Departamento de Bioloxía, Universidade da Coruña, A Coruña, Spain
| | - Raul Escandell
- SOM (Societat Ornitològica de Menorca), Es Castell, Menorca, Spain
| | - Antonio Sánchez
- Oficina Técnica Devesa-Albufera (Ayuntamiento de Valencia), Valencia, Spain
| | - Beneharo Rodríguez
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
- Canary Islands' Ornithology and Natural History Group (GOHNIC), Tenerife, Canary Islands, Spain
| | - José M Arcos
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | - Daniel Oro
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
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9
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McClanahan TR, Kosgei JK. Redistribution of benefits but not detection in a fisheries bycatch-reduction management initiative. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2018; 32:159-170. [PMID: 28678422 DOI: 10.1111/cobi.12980] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 06/28/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Reducing the capture of small fish, discarded fish, and bycatch is a primary concern of fisheries managers who propose to maintain high yields, species diversity, and ecosystem functions. Modified fishing gear is one of the primary ways to reduce by-catch and capture of small fish. The outcomes of gear modification may depend on competition among fishers using other similar resources and other gears in the same fishing grounds and the subsequent adoption or abandonment of modified gears by fishers. We evaluated adoption of modified gear, catch size, catch per unit effort (CPUE), yield, and fisher incomes in a coral reef fishery in which a 3-cm escape gap was introduced into traditional traps. There were 26.1 (SD 4.9) fishers who used the experimental landing sites and 228(SD 15.7) fishers who used the control landing sites annually over 7 years. The size of fish increased by 10.6% in the modified traps, but the catch of smaller fish increased by 11.2% among the other gears. There was no change in the overall CPUE, yields, or per area incomes; rather, yield benefits were redistributed in favor of the unmodified gears. For example, estimated incomes of fishers who adopted the modified traps remained unchanged but increased for net and spear fishers. Fishers using escape-gap traps had a high proportion of income from larger fish, which may have led to a perception of benefits, high status, and no abandonment of the modified traps. The commensal rather than competitive outcome may explain the continued use of escape-gap traps 3 years after their introduction. Trap fishers showed an interest in negotiating other management improvements, such as increased mesh sizes for nets, which could ultimately catalyze community-level decisions and restrictions that could increase their profits.
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Affiliation(s)
- T R McClanahan
- Wildlife Conservation Society, Marine Program, Bronx, NY 10460, U.S.A
- Wildlife Conservation Society, Coral Reef Conservation Project, P.O. Box 99470, Mombasa, Kenya
| | - J K Kosgei
- Wildlife Conservation Society, Coral Reef Conservation Project, P.O. Box 99470, Mombasa, Kenya
- Pwani University, P.O. Box 195-80108, Kilifi, Kenya
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10
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Stewart KR, LaCasella EL, Roden SE, Jensen MP, Stokes LW, Epperly SP, Dutton PH. Nesting population origins of leatherback turtles caught as bycatch in the U.S. pelagic longline fishery. Ecosphere 2016. [DOI: 10.1002/ecs2.1272] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Kelly R. Stewart
- The Ocean Foundation 1320 19th Street, NW, 5th Floor, The Sunderland Building Washington District of Columbia 20036 USA
- Marine Mammal and Turtle DivisionSouthwest Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 8901 La Jolla Shores Dr. La Jolla California 92037 USA
| | - Erin L. LaCasella
- Marine Mammal and Turtle DivisionSouthwest Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 8901 La Jolla Shores Dr. La Jolla California 92037 USA
| | - Suzanne E. Roden
- Marine Mammal and Turtle DivisionSouthwest Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 8901 La Jolla Shores Dr. La Jolla California 92037 USA
| | - Michael P. Jensen
- Marine Mammal and Turtle DivisionSouthwest Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 8901 La Jolla Shores Dr. La Jolla California 92037 USA
| | - Lesley W. Stokes
- Protected Resources and Biodiversity DivisionSoutheast Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 75 Virginia Beach Drive Miami Florida 33149 USA
| | - Sheryan P. Epperly
- Protected Resources and Biodiversity DivisionSoutheast Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 75 Virginia Beach Drive Miami Florida 33149 USA
| | - Peter H. Dutton
- Marine Mammal and Turtle DivisionSouthwest Fisheries Science CenterNational Marine Fisheries ServiceNational Oceanic and Atmospheric Administration 8901 La Jolla Shores Dr. La Jolla California 92037 USA
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Exploring Spatiotemporal Trends in Commercial Fishing Effort of an Abalone Fishing Zone: A GIS-Based Hotspot Model. PLoS One 2015; 10:e0122995. [PMID: 25992800 PMCID: PMC4439149 DOI: 10.1371/journal.pone.0122995] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 02/26/2015] [Indexed: 11/19/2022] Open
Abstract
Assessing patterns of fisheries activity at a scale related to resource exploitation has received particular attention in recent times. However, acquiring data about the distribution and spatiotemporal allocation of catch and fishing effort in small scale benthic fisheries remains challenging. Here, we used GIS-based spatio-statistical models to investigate the footprint of commercial diving events on blacklip abalone (Haliotis rubra) stocks along the south-west coast of Victoria, Australia from 2008 to 2011. Using abalone catch data matched with GPS location we found catch per unit of fishing effort (CPUE) was not uniformly spatially and temporally distributed across the study area. Spatial autocorrelation and hotspot analysis revealed significant spatiotemporal clusters of CPUE (with distance thresholds of 100’s of meters) among years, indicating the presence of CPUE hotspots focused on specific reefs. Cumulative hotspot maps indicated that certain reef complexes were consistently targeted across years but with varying intensity, however often a relatively small proportion of the full reef extent was targeted. Integrating CPUE with remotely-sensed light detection and ranging (LiDAR) derived bathymetry data using generalized additive mixed model corroborated that fishing pressure primarily coincided with shallow, rugose and complex components of reef structures. This study demonstrates that a geospatial approach is efficient in detecting patterns and trends in commercial fishing effort and its association with seafloor characteristics.
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12
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Watson JT, Bigelow KA. Trade-offs among catch, bycatch, and landed value in the American Samoa longline fishery. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:1012-1022. [PMID: 24628499 DOI: 10.1111/cobi.12268] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 11/19/2013] [Indexed: 06/03/2023]
Abstract
The interspecific preferences of fishes for different depths and habitats suggest fishers could avoid unwanted catches of some species while still effectively targeting other species. In pelagic longline fisheries, albacore (Thunnus alalunga) are often caught in relatively cooler, deeper water (>100 m) than many species of conservation concern (e.g., sea turtles, billfishes, and some sharks) that are caught in shallower water (<100 m). From 2007 to 2011, we examined the depth distributions of hooks for 1154 longline sets (3,406,946 hooks) and recorded captures by hook position on 2642 sets (7,829,498 hooks) in the American Samoa longline fishery. Twenty-three percent of hooks had a settled depth <100 m. Individuals captured in the 3 shallowest hook positions accounted for 18.3% of all bycatch. We analyzed hypothetical impacts for 25 of the most abundant species caught in the fishery by eliminating the 3 shallowest hook positions under scenarios with and without redistribution of these hooks to deeper depths. Distributions varied by species: 45.5% (n = 10) of green sea turtle (Chelonia mydas), 59.5% (n = 626) of shortbill spearfish (Tetrapturus angustirostris), 37.3% (n = 435) of silky shark (Carcharhinus falciformis), and 42.6% (n = 150) of oceanic whitetip shark (C. longimanus) were caught on the 3 shallowest hooks. Eleven percent (n = 20,435) of all tuna and 8.5% (n = 10,374) of albacore were caught on the 3 shallowest hooks. Hook elimination reduced landed value by 1.6-9.2%, and redistribution of hooks increased average annual landed value relative to the status quo by 5-11.7%. Based on these scenarios, redistribution of hooks to deeper depths may provide an economically feasible modification to longline gear that could substantially reduce bycatch for a suite of vulnerable species. Our results suggest that this method may be applicable to deep-set pelagic longline fisheries worldwide.
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Affiliation(s)
- Jordan T Watson
- Joint Institute for Marine and Atmospheric Research, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822, U.S.A.; University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, 17109 Pt Lena Loop Road, Juneau, AK 99801, U.S.A..
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13
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Soykan CU, Eguchi T, Kohin S, Dewar H. Prediction of fishing effort distributions using boosted regression trees. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2014; 24:71-83. [PMID: 24640535 DOI: 10.1890/12-0826.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Concerns about bycatch of protected species have become a dominant factor shaping fisheries management. However, efforts to mitigate bycatch are often hindered by a lack of data on the distributions of fishing effort and protected species. One approach to overcoming this problem has been to overlay the distribution of past fishing effort with known locations of protected species, often obtained through satellite telemetry and occurrence data, to identify potential bycatch hotspots. This approach, however, generates static bycatch risk maps, calling into question their ability to forecast into the future, particularly when dealing with spatiotemporally dynamic fisheries and highly migratory bycatch species. In this study, we use boosted regression trees to model the spatiotemporal distribution of fishing effort for two distinct fisheries in the North Pacific Ocean, the albacore (Thunnus alalunga) troll fishery and the California drift gillnet fishery that targets swordfish (Xiphias gladius). Our results suggest that it is possible to accurately predict fishing effort using < 10 readily available predictor variables (cross-validated correlations between model predictions and observed data -0.6). Although the two fisheries are quite different in their gears and fishing areas, their respective models had high predictive ability, even when input data sets were restricted to a fraction of the full time series. The implications for conservation and management are encouraging: Across a range of target species, fishing methods, and spatial scales, even a relatively short time series of fisheries data may suffice to accurately predict the location of fishing effort into the future. In combination with species distribution modeling of bycatch species, this approach holds promise as a mitigation tool when observer data are limited. Even in data-rich regions, modeling fishing effort and bycatch may provide more accurate estimates of bycatch risk than partial observer coverage for fisheries and bycatch species that are heavily influenced by dynamic oceanographic conditions.
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14
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Senko J, White ER, Heppell SS, Gerber LR. Comparing bycatch mitigation strategies for vulnerable marine megafauna. Anim Conserv 2013. [DOI: 10.1111/acv.12051] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Senko
- School of Life Sciences; Arizona State University; Tempe AZ USA
| | - E. R. White
- School of Life Sciences; Arizona State University; Tempe AZ USA
| | - S. S. Heppell
- Department of Fisheries and Wildlife; Oregon State University; Corvallis OR USA
| | - L. R. Gerber
- School of Life Sciences; Arizona State University; Tempe AZ USA
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15
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Wallace BP, Kot CY, DiMatteo AD, Lee T, Crowder LB, Lewison RL. Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities. Ecosphere 2013. [DOI: 10.1890/es12-00388.1] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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16
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Arendt MD, Boynton J, Schwenter JA, Byrd JI, Segars AL, Whitaker JD, Parker L, Owens DW, Blanvillain GM, Quattro JM, Roberts MA. Spatial clustering of loggerhead sea turtles in coastal waters of the NW Atlantic Ocean: implications for management surveys. ENDANGER SPECIES RES 2012. [DOI: 10.3354/esr00450] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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Van Houtan KS, Halley JM. Long-term climate forcing in loggerhead sea turtle nesting. PLoS One 2011; 6:e19043. [PMID: 21589639 PMCID: PMC3083431 DOI: 10.1371/journal.pone.0019043] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 03/24/2011] [Indexed: 11/19/2022] Open
Abstract
The long-term variability of marine turtle populations remains poorly understood, limiting science and management. Here we use basin-scale climate indices and regional surface temperatures to estimate loggerhead sea turtle (Caretta caretta) nesting at a variety of spatial and temporal scales. Borrowing from fisheries research, our models investigate how oceanographic processes influence juvenile recruitment and regulate population dynamics. This novel approach finds local populations in the North Pacific and Northwest Atlantic are regionally synchronized and strongly correlated to ocean conditions--such that climate models alone explain up to 88% of the observed changes over the past several decades. In addition to its performance, climate-based modeling also provides mechanistic forecasts of historical and future population changes. Hindcasts in both regions indicate climatic conditions may have been a factor in recent declines, but future forecasts are mixed. Available climatic data suggests the Pacific population will be significantly reduced by 2040, but indicates the Atlantic population may increase substantially. These results do not exonerate anthropogenic impacts, but highlight the significance of bottom-up oceanographic processes to marine organisms. Future studies should consider environmental baselines in assessments of marine turtle population variability and persistence.
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Affiliation(s)
- Kyle S Van Houtan
- Marine NOAA Fisheries Service, Pacific Islands Fisheries Science Center, Honolulu, Hawaii, United States of America.
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18
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Mendez M, Rosenbaum HC, Wells RS, Stamper A, Bordino P. Genetic evidence highlights potential impacts of by-catch to cetaceans. PLoS One 2010; 5:e15550. [PMID: 21179542 PMCID: PMC3002289 DOI: 10.1371/journal.pone.0015550] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 11/10/2010] [Indexed: 11/18/2022] Open
Abstract
Incidental entanglement in fishing gear is arguably the most serious threat to many populations of small cetaceans, judging by the alarming number of captured animals. However, other aspects of this threat, such as the potential capture of mother-offspring pairs or reproductive pairs, could be equally or even more significant but have rarely been evaluated. Using a combination of demographic and genetic data we provide evidence that i) Franciscana dolphin pairs that are potentially reproductive and mother-offspring pairs form temporal bonds, and ii) are entangled simultaneously. Our results highlight potential demographic and genetic impacts of by-catch to cetacean populations: the joint entanglement of mother-offspring or reproductive pairs, compared to random individuals, might exacerbate the demographic consequences of by-catch, and the loss of groups of relatives means that significant components of genetic diversity could be lost together. Given the social nature of many odontocetes (toothed cetaceans), we suggest that these potential impacts could be rather general to the group and therefore by-catch could be more detrimental than previously considered.
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Affiliation(s)
- Martin Mendez
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, United States of America.
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Wallace BP, Lewison RL, McDonald SL, McDonald RK, Kot CY, Kelez S, Bjorkland RK, Finkbeiner EM, Helmbrecht S, Crowder LB. Global patterns of marine turtle bycatch. Conserv Lett 2010. [DOI: 10.1111/j.1755-263x.2010.00105.x] [Citation(s) in RCA: 199] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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