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Okuyama J, Watabe A, Takuma S, Tanaka K, Shirai K, Murakami‐Sugihara N, Arita M, Fujita K, Nishizawa H, Narazaki T, Yamashita Y, Kameda K. Latitudinal cline in the foraging dichotomy of loggerhead sea turtles reveals the importance of East China Sea for priority conservation. DIVERS DISTRIB 2022. [DOI: 10.1111/ddi.13531] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Junichi Okuyama
- Fisheries Technology Institute Japan Fisheries Research and Education Agency Ishigaki Okinawa Japan
| | - Akemi Watabe
- Ichinomiya Sea Turtle Association Ichinomiya Chiba Japan
| | | | - Kentaro Tanaka
- Atmosphere and Ocean Research Institute The University of Tokyo Chiba Japan
| | - Kotaro Shirai
- Atmosphere and Ocean Research Institute The University of Tokyo Chiba Japan
| | | | - Mamiko Arita
- Graduate School of Agriculture Kindai University Nara Japan
| | - Kento Fujita
- Graduate School of Informatics Kyoto University Yoshida Honmachi Kyoto Japan
| | - Hideaki Nishizawa
- Graduate School of Informatics Kyoto University Yoshida Honmachi Kyoto Japan
| | - Tomoko Narazaki
- Atmosphere and Ocean Research Institute The University of Tokyo Chiba Japan
- Faculty of Agriculture Meijo University Nagoya Aichi Japan
| | | | - Kazunari Kameda
- Kuroshima Research Institute Sea Turtle Association of Japan Taketomi Okinawa Japan
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Net illumination reduces fisheries bycatch, maintains catch value, and increases operational efficiency. Curr Biol 2022; 32:911-918.e2. [PMID: 35063121 DOI: 10.1016/j.cub.2021.12.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/04/2021] [Accepted: 12/17/2021] [Indexed: 11/20/2022]
Abstract
Small-scale fisheries are vital for food security, nutrition, and livelihoods in coastal areas throughout the world's oceans.1-9 As intricately linked social-ecological systems, small-scale fisheries require management approaches that help ensure both ecological and socioeconomic sustainability.7,10-14 Given their ease of use and lucrative nature, coastal gillnet fisheries are globally ubiquitous.10,15 However, these fisheries often result in high discarded capture of non-target organisms (bycatch) that can lead to significant cascading effects throughout trophic chains16-18 and costly fisheries restrictions that result in important revenue losses in coastal communities with scarce economic alternatives.19,20 Despite these challenges, few solutions have been developed and broadly adopted to decrease bycatch in coastal gillnet fisheries, particularly in developing nations.5,21 Here we used controlled experiments along Mexico's Baja California peninsula to show that illuminating gillnets with green LED lights-an emerging technology originally developed to mitigate sea turtle bycatch-significantly reduced mean rates of total discarded bycatch biomass by 63%, which included significant decreases in elasmobranch (95%), Humboldt squid (81%), and unwanted finfish (48%). Moreover, illuminated nets significantly reduced the mean time required to retrieve and disentangle nets by 57%. In contrast, there were no significant differences in target fish catch or value. These findings advance our understanding of how artificial illumination affects operational efficiency and changes in catch rates in coastal gillnet fisheries, while illustrating the value of assessing broad-scale ecological and socioeconomic effects of species-specific conservation strategies.
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Comparison of UAV and Boat Surveys for Detecting Changes in Breeding Population Dynamics of Sea Turtles. REMOTE SENSING 2021. [DOI: 10.3390/rs13152857] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Surveying the breeding population of a given species can be difficult for many logistic reasons. Marine turtles are a challenging taxon for the study of reproductive ecology and breeding strategies, because turtles aggregate off-shore and males remain exclusively at sea. For successful management of sea turtle populations, determining operational sex ratios (OSRs) on a continuing basis is critical for determining long-term population viability, particularly in the context of changing hatchling sex ratios due to temperature-dependent sex determination in a warming climate. To understand how survey technique and stage of the breeding season might influence the ability to detect turtles and determine OSRs, we surveyed the presence and identified the sex of adult male and female green sea turtles (Chelonia mydas) using a boat and small commercial unoccupied/unmanned aerial vehicle (UAV), at the start (October) and peak (December) of a nesting season at an important breeding site at Heron Island, Great Barrier Reef, Australia. The ratio of males to females within the breeding ground detected by both survey methods changed from being male-biased in October to heavily female-biased in December, indicating that most males cease their reproductive effort and depart before the peak of the nesting season. Surveying with a UAV more than doubled the rate of turtles seen per minute of survey effort compared with surveying solely from the boat and allowed surveys to be conducted at times and/or places unsafe or inaccessible for boats. The sex of a slightly greater proportion of turtles seen could not be identified by observers using a UAV versus a boat, although more turtles were detected using the UAV. The departure of many males during the peak of the nesting season is likely due to an increasing biological cost of residency in the area because males encounter fewer receptive females as the season progresses and the limited foraging opportunity is insufficient to support the number of males present. Overall, we found that UAVs are an effective tool for studying important but difficult to observe aspects of sea turtle biology.
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Morales-Zárate M, López-Ramírez J, Salinas-Zavala C. Loggerhead marine turtle (Caretta caretta) ecological facts from a trophic relationship model in a hot spot fishery area: Gulf of Ulloa, Mexico. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2020.109327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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5
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Benson SR, Forney KA, Moore JE, LaCasella EL, Harvey JT, Carretta JV. A long-term decline in the abundance of endangered leatherback turtles, Dermochelys coriacea, at a foraging ground in the California Current Ecosystem. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Lavaniegos BE. Hyperiid amphipods from the Gulf of Ulloa and offshore region, Baja California: The possible role of the gelatinous zooplankton as a transport vector into the coastal shelf waters. PLoS One 2020; 15:e0233071. [PMID: 33151968 PMCID: PMC7643982 DOI: 10.1371/journal.pone.0233071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/09/2020] [Indexed: 11/19/2022] Open
Abstract
Hyperiid amphipod species from the Gulf of Ulloa, Baja California, and the adjacent region (from the shelf break to 200 km offshore) were analyzed to evaluate diversity and abundances. This productive area supports small-scale commercial fisheries, including sand bass (Paralabrax nebulifer), California spiny lobster (Panulirus interruptus), abalones, clams, and others. Strong coastal upwelling events were observed during summer seasons of the period 2002-2008 between Punta Eugenia and Punta Abreojos. The upwelling plumes at Punta Abreojos are transported southward in slope waters bordering the coastal shelf of the Gulf of Ulloa, contributing to the separation of coastal and oceanic regions, and explain differences in amphipod diversity and abundances between both regions. In the offshore region, the most abundant species were Vibilia armata, Lestrigonus schizogeneios, Primno brevidens, and Eupronoe minuta, similar to previous findings in northern regions of Baja California and southern California. However, abundances of these species were lower (10-30 individuals/1000 m3), only reaching 20-50% of abundance levels reported off northern Baja California. In the coastal shelf of the Gulf of Ulloa, amphipods were virtually absent during 2002, 2003 and 2006. However, during 2004 and 2005, abundances of P. brevidens increased (54 and 20 ind/1000 m3, respectively). Moreover, during the late summer of 2007, abundances of L. schizogeneios, P. brevidens, Lycaea nasuta, Lycaea pulex, and Simorhynchotus antennarius increased considerably (261, 39, 31, 68, 416 ind/1000 m3, respectively), indicating occasional utilization of the coastal shelf by pelagic amphipods. Changes in gelatinous populations (medusae, siphonophores, ctenophores, doliolids, and salps) paralleled changes in hyperiid populations, with highest abundances in 2005-2008 in the coastal shelf. Significant correlations of 17 amphipod species with gelatinous taxa, which are often used as host organisms by hyperiid amphipods, suggest that gelatinous presence enhanced hyperiid abundance and promoted the progression of hyperiid amphipods onto the coastal shelf during parts of the 2002-2008 period.
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Affiliation(s)
- Bertha E. Lavaniegos
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y Educación Superior de Ensenada, Baja California, México
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Mugo R, Saitoh SI, Igarashi H, Toyoda T, Masuda S, Awaji T, Ishikawa Y. Identification of skipjack tuna (Katsuwonus pelamis) pelagic hotspots applying a satellite remote sensing-driven analysis of ecological niche factors: A short-term run. PLoS One 2020; 15:e0237742. [PMID: 32817669 PMCID: PMC7440647 DOI: 10.1371/journal.pone.0237742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/31/2020] [Indexed: 11/18/2022] Open
Abstract
Skipjack tuna (SJT) pelagic hotspots in the western North Pacific (WNP) were modelled using fishery and satellite remotely sensed data with Ecological Niche Factor Analysis (ENFA) models. Our objectives were to model and predict habitat hotspots for SJT and assess the monthly changes in sub-surface temperatures and mixed layer depths at fishing locations. SJT presence-only monthly resolved data, sea surface temperature, chlorophyll-a, diffuse attenuation coefficient, sea surface heights and surface wind speed were used to construct ENFA models and generate habitat suitability indices using a short-term dataset from March-November 2004. The suitability indices were then predicted for July-October (2007 and 2008). Monthly aggregated polygons of areas fished by skipjack tuna pole and line vessels were also overlaid on the predicted habitat suitability maps. Distributions of sub-surface temperatures and mixed layer depths (MLD) at fishing locations were also examined. Our results showed good fit for ENFA models, as indicated by the absolute validation index, the contrast validation index and the continuous Boyce index. The predicted hotspots showed varying concurrences when compared with 25-degree polygons derived from fished areas. Northward shifts in SJT hotspots corresponded with declining MLDs from March to September. The MLDs were shallower in summer and deeper in autumn and winter months. The habitat hotspots modeled using ENFA were consistent with the known ecology and seasonal migration pattern of SJT. The findings of this work, derived from a short-term dataset, enable identification of SJT hotspots in the WNP, thus contributing valuable information for future research on SJT habitat prediction models.
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Affiliation(s)
- Robinson Mugo
- Regional Center for Mapping of Resources for Development, Nairobi, Kenya
- * E-mail:
| | - Sei-Ichi Saitoh
- Arctic Research Center, Hokkaido University, Hokkaido, Japan
| | - Hiromichi Igarashi
- Information Engineering Program, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Takahiro Toyoda
- Oceanography and Geochemistry Research Department, Meteorological Research Institute, Japan Meteorological Agency, Yokosuka, Japan
| | - Shuhei Masuda
- Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
| | | | - Yoichi Ishikawa
- Information Engineering Program, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
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8
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Clinical pathology and health reference values for loggerhead sea turtles (Caretta caretta) and olive ridley turtles (Lepidochelys olivacea) in the Gulf of Ulloa, Baja California Sur, Mexico. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s00580-019-02985-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Hays GC, Bailey H, Bograd SJ, Bowen WD, Campagna C, Carmichael RH, Casale P, Chiaradia A, Costa DP, Cuevas E, Nico de Bruyn PJ, Dias MP, Duarte CM, Dunn DC, Dutton PH, Esteban N, Friedlaender A, Goetz KT, Godley BJ, Halpin PN, Hamann M, Hammerschlag N, Harcourt R, Harrison AL, Hazen EL, Heupel MR, Hoyt E, Humphries NE, Kot CY, Lea JSE, Marsh H, Maxwell SM, McMahon CR, Notarbartolo di Sciara G, Palacios DM, Phillips RA, Righton D, Schofield G, Seminoff JA, Simpfendorfer CA, Sims DW, Takahashi A, Tetley MJ, Thums M, Trathan PN, Villegas-Amtmann S, Wells RS, Whiting SD, Wildermann NE, Sequeira AMM. Translating Marine Animal Tracking Data into Conservation Policy and Management. Trends Ecol Evol 2019; 34:459-473. [PMID: 30879872 DOI: 10.1016/j.tree.2019.01.009] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 11/18/2022]
Abstract
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.
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Affiliation(s)
| | - Helen Bailey
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD 20688, USA
| | - Steven J Bograd
- NOAA Southwest Fisheries Science Center, Environmental Research Division, Monterey, CA 93940, USA
| | - W Don Bowen
- Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, NS B2Y 4A2, Canada
| | - Claudio Campagna
- Wildlife Conservation Society, Marine Program, Buenos Aires, 1414 Argentina
| | - Ruth H Carmichael
- University Programs, Dauphin Island Sea Lab, Dauphin Island, AL 36528, USA; Department of Marine Sciences, University of South Alabama, Mobile, AL 36688, USA
| | - Paolo Casale
- Department of Biology, University of Pisa, Pisa, Italy
| | - Andre Chiaradia
- Conservation Department, Phillip Island, Nature Parks, Victoria, Australia
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Eduardo Cuevas
- CONACYT - Research Center of Environmental Sciences, Faculty of Natural Sciences, Universidad Autonoma del Carmen, Campeche 24180, Mexico; Pronatura Peninsula de Yucatan, Yucatan 97205, Mexico
| | - P J Nico de Bruyn
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield 0028, South Africa
| | - Maria P Dias
- BirdLife International, Cambridge CB2 3QZ, UK; MARE - Marine and Environmental Sciences Center, ISPA - Instituto Universitário, 1149-041 Lisboa, Portugal
| | - Carlos M Duarte
- King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, 23955-6900, Saudi Arabia
| | - Daniel C Dunn
- Marine Geospatial Ecology Lab, Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Peter H Dutton
- Marine Mammal and Turtle Division, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
| | - Nicole Esteban
- Department of Biosciences, Swansea University, Swansea SA2 8PP, Wales, UK
| | - Ari Friedlaender
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA; Institute for Marine Sciences, University of California Santa Cruz, Santa Cruz, CA 965060, USA
| | - Kimberly T Goetz
- National Institute of Water & Atmospheric Research Ltd (NIWA),Greta Point, Wellington, New Zealand
| | - Brendan J Godley
- Marine Turtle Research Group, Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Patrick N Halpin
- Marine Geospatial Ecology Lab, Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Mark Hamann
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Neil Hammerschlag
- Rosenstiel School of Marine & Atmospheric Science, Abess Center for Ecosystem Science & Policy, University of Miami, Miami, FL 33149, USA
| | - Robert Harcourt
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Autumn-Lynn Harrison
- Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC 20008, USA
| | - Elliott L Hazen
- NOAA Southwest Fisheries Science Center, Environmental Research Division, Monterey, CA 93940, USA
| | - Michelle R Heupel
- Australian Institute of Marine Science, Townsville, QLD 4810, Australia
| | - Erich Hoyt
- Whale and Dolphin Conservation, Bridport, Dorset, UK; IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, Gland, Switzerland
| | - Nicolas E Humphries
- Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, UK
| | - Connie Y Kot
- Marine Geospatial Ecology Lab, Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - James S E Lea
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Helene Marsh
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Sara M Maxwell
- School of Interdisciplinary Arts and Sciences, University of Washington, Bothell Campus, Bothell, WA 98011, USA
| | - Clive R McMahon
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; Ecology and Biodiversity Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia; Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
| | - Giuseppe Notarbartolo di Sciara
- Tethys Research Institute, 20121 Milano, Italy; IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, Gland, Switzerland
| | - Daniel M Palacios
- Marine Mammal Institute and Department of Fisheries and Wildlife, Oregon State University, Newport, OR 97365, USA
| | - Richard A Phillips
- British Antarctic Survey, Natural Environment Research Council, Cambridge, CB3 0ET, UK
| | - David Righton
- Cefas Laboratory, Suffolk, NR33 0HT, UK; School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Gail Schofield
- School of Biological and Chemical Sciences, Queen Mary University of London, E14NS, London, UK
| | - Jeffrey A Seminoff
- Marine Turtle Ecology and Assessment Program, NOAA-Southwest Fisheries Science Center, La Jolla, CA 92037, USA
| | - Colin A Simpfendorfer
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - David W Sims
- Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, UK; Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, Southampton, SO14 3ZH, UK; Centre for Biological Sciences, Building 85, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
| | - Akinori Takahashi
- National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
| | - Michael J Tetley
- IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, Gland, Switzerland
| | - Michele Thums
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre (M096), University of Western Australia, Crawley, WA 6009, Australia
| | - Philip N Trathan
- IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, Gland, Switzerland
| | - Stella Villegas-Amtmann
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Randall S Wells
- Chicago Zoological Society's Sarasota Dolphin Research Program, c/o Mote Marine Laboratory, Sarasota, FL 34236, USA
| | - Scott D Whiting
- Marine Science Program, Department of Biodiversity, Conservation, and Attractions, Kensington, WA 6151, Australia
| | - Natalie E Wildermann
- Marine Turtle Research, Ecology and Conservation Group, Department of Earth, Ocean and Atmospheric, Science, Florida State University, Tallahassee, FL 32306-4320, USA
| | - Ana M M Sequeira
- IOMRC and The University of Western Australia Oceans Institute, School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia
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10
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Barco SG, Burt ML, DiGiovanni RA, Swingle WM, Williard AS. Loggerhead turtle Caretta caretta density and abundance in Chesapeake Bay and the temperate ocean waters of the southern portion of the Mid-Atlantic Bight. ENDANGER SPECIES RES 2018. [DOI: 10.3354/esr00917] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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11
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Wildermann NE, Gredzens C, Avens L, Barrios-Garrido HA, Bell I, Blumenthal J, Bolten AB, Braun McNeill J, Casale P, Di Domenico M, Domit C, Epperly SP, Godfrey MH, Godley BJ, González-Carman V, Hamann M, Hart KM, Ishihara T, Mansfield KL, Metz TL, Miller JD, Pilcher NJ, Read MA, Sasso C, Seminoff JA, Seney EE, Willard AS, Tomás J, Vélez-Rubio GM, Ware M, Williams JL, Wyneken J, Fuentes MMPB. Informing research priorities for immature sea turtles through expert elicitation. ENDANGER SPECIES RES 2018. [DOI: 10.3354/esr00916] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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12
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Nykänen M, Jessopp M, Doyle TK, Harman LA, Cañadas A, Breen P, Hunt W, Mackey M, Cadhla OÓ, Reid D, Rogan E. Using tagging data and aerial surveys to incorporate availability bias in the abundance estimation of blue sharks (Prionace glauca). PLoS One 2018; 13:e0203122. [PMID: 30204764 PMCID: PMC6133345 DOI: 10.1371/journal.pone.0203122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/15/2018] [Indexed: 01/08/2023] Open
Abstract
There is worldwide concern about the status of elasmobranchs, primarily as a result of overfishing and bycatch with subsequent ecosystem effects following the removal of top predators. Whilst abundant and wide-ranging, blue sharks (Prionace glauca) are the most heavily exploited shark species having suffered marked declines over the past decades, and there is a call for robust abundance estimates. In this study, we utilized depth data collected from two blue sharks using pop-up satellite archival tags, and modelled the proportion of time the sharks were swimming in the top 1-meter layer and could therefore be detected by observers conducting aerial surveys. The availability models indicated that the tagged sharks preferred surface waters whilst swimming over the continental shelf and during daytime, with a model-predicted average proportion of time spent at the surface of 0.633 (SD = 0.094) for on-shelf, and 0.136 (SD = 0.075) for off-shelf. These predicted values were then used to account for availability bias in abundance estimates for the species over a large area in the Northeast Atlantic, derived through distance sampling using aerial survey data collected in 2015 and 2016 and modelled with density surface models. Further, we compared abundance estimates corrected with model-predicted availability to uncorrected estimates and to estimates that incorporated the average time the sharks were available for detection. The mean abundance (number of individuals) corrected with modelled availability was 15,320 (CV = 0.28) in 2015 and 11,001 (CV = 0.27) in 2016. Depending on the year, these estimates were ~7 times higher compared to estimates without the bias correction, and ~3 times higher compared to the abundances corrected with average availability. When the survey area contains habitat heterogeneity that may affect surfacing patterns of animals, modelling animals' availability provides a robust alternative to correcting for availability bias and highlights the need for caution when applying "average" correction factors.
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Affiliation(s)
- Milaja Nykänen
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
| | - Mark Jessopp
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland
| | - Thomas K. Doyle
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
| | - Luke A. Harman
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
| | - Ana Cañadas
- ALNILAM Research and Conservation Ltd, Madrid, Spain
| | - Patricia Breen
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- School of Geography, National University of Ireland, Galway, Ireland
| | - William Hunt
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
| | - Mick Mackey
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
| | - Oliver Ó Cadhla
- National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht, Galway, Ireland
| | - David Reid
- Marine Institute, Oranmore, Galway, Ireland
| | - Emer Rogan
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
- Aquaculture & Fisheries Development Centre, University College Cork, Cork, Ireland
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Carretta JV. A machine-learning approach to assign species to ‘unidentified’ entangled whales. ENDANGER SPECIES RES 2018. [DOI: 10.3354/esr00894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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14
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Rees AF, Avens L, Ballorain K, Bevan E, Broderick AC, Carthy RR, Christianen MJA, Duclos G, Heithaus MR, Johnston DW, Mangel JC, Paladino F, Pendoley K, Reina RD, Robinson NJ, Ryan R, Sykora-Bodie ST, Tilley D, Varela MR, Whitman ER, Whittock PA, Wibbels T, Godley BJ. The potential of unmanned aerial systems for sea turtle research and conservation: a review and future directions. ENDANGER SPECIES RES 2018. [DOI: 10.3354/esr00877] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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15
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Briscoe DK, Parker DM, Balazs GH, Kurita M, Saito T, Okamoto H, Rice M, Polovina JJ, Crowder LB. Active dispersal in loggerhead sea turtles (Caretta caretta) during the 'lost years'. Proc Biol Sci 2017; 283:rspb.2016.0690. [PMID: 27252021 DOI: 10.1098/rspb.2016.0690] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/09/2016] [Indexed: 11/12/2022] Open
Abstract
Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their 'lost years' at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1-3 year old turtles released off Japan (29.7-37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.
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Affiliation(s)
- D K Briscoe
- Biology, Stanford University, Hopkins Marine Station, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA
| | - D M Parker
- Joint Institute for Marine and Atmospheric Research, National Oceanic and Atmospheric Administration, 2032 Southeast Oregon State University Drive, Newport, OR 97365, USA
| | - G H Balazs
- Pacific Islands Fisheries Science Center, National Oceanic and Atmospheric Administration Inouye Regional Center, National Marine Fisheries Service, 1845 WASP Boulevard Building 176, Honolulu, HI 96818, USA
| | - M Kurita
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - T Saito
- Usa Marine Biological Institute, Kochi University, Usa Tosa, Kochi 781-1164, Japan
| | - H Okamoto
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - M Rice
- Hawaii Preparatory Academy, 65-1692 Kohala Mountain Road, Kamuela, HI 96743, USA
| | - J J Polovina
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya 455-0033, Japan
| | - L B Crowder
- Biology, Stanford University, Hopkins Marine Station, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA Center for Ocean Solutions, Stanford University, 99 Pacific Street, Suite 555E, Monterey, CA 93949, USA
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16
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Ley-Quiñónez CP, Rossi-Lafferriere NA, Espinoza-Carreon TL, Hart CE, Peckham SH, Aguirre AA, Zavala-Norzagaray AA. Associations between trace elements and clinical health parameters in the North Pacific loggerhead sea turtle (Caretta caretta) from Baja California Sur, Mexico. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:9530-9537. [PMID: 28238183 DOI: 10.1007/s11356-017-8556-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 02/02/2017] [Indexed: 06/06/2023]
Abstract
This study investigated selected trace elements toxicity in sea turtles Caretta caretta population from Baja California Sur (BCS), Mexico, by analyzing associations among Zn, Se, Cu, As, Cd, Ni, Mn, Pb, and Hg with various biochemical parameters (packed cell volume, leukocytes, and selected blood parameters), and whether their concentrations could have an impact on the health status of sea turtles. Blood samples from 22 loggerhead (C. caretta) sea turtles from BCS, Mexico, were collected for trace elements on biochemistry parameter analyses. Significant associations among trace element levels and the biochemistry parameters were found: Cd vs ALP (R 2 = 0.874, p ˂ 0.001), As vs ALP (R 2 = 0.656, p ˂ 0.001), Mn vs ALP (R 2 = 0.834, p ˂ 0.001), and Ni vs LDH (R 2 = 0.587, p ˂ 0.001). This study is the first report of the biochemical parameters of the North Pacific loggerhead sea turtle (C. caretta) from Baja California Sur, Mexico, and it is the first to observe several associations with toxic and essential trace elements. Our study reinforces the usefulness of blood for the monitoring of the levels of contaminating elements and the results suggest that, based on the associations with health clinical parameters, high levels of Cd and As could be representing a risk to the North Pacific loggerhead population health.
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Affiliation(s)
- César Paúl Ley-Quiñónez
- Instituto Politécnico Nacional, CIIDIR-SINALOA, Guasave, Sinaloa, Mexico.
- Grupo Tortuguero de las Californias A.C, La Paz, Baja California Sur, Mexico.
- Investigación, Capacitación y Soluciones Ambientas y Sociales A.C, Tepic, Nayarit, Mexico.
| | | | | | - Catherine Edwina Hart
- Grupo Tortuguero de las Californias A.C, La Paz, Baja California Sur, Mexico
- Investigación, Capacitación y Soluciones Ambientas y Sociales A.C, Tepic, Nayarit, Mexico
| | - Sherwood Hoyt Peckham
- SmartFish, La Paz, Baja California Sur, Mexico
- Center for Ocean Solutions, Stanford University, Pacific Grove, CA, USA
| | - Alfredo Alonso Aguirre
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
| | - Alan Alfredo Zavala-Norzagaray
- Instituto Politécnico Nacional, CIIDIR-SINALOA, Guasave, Sinaloa, Mexico
- Grupo Tortuguero de las Californias A.C, La Paz, Baja California Sur, Mexico
- Investigación, Capacitación y Soluciones Ambientas y Sociales A.C, Tepic, Nayarit, Mexico
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17
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Rees ALF, Carreras C, Broderick AC, Margaritoulis D, Stringell TB, Godley BJ. Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds. MARINE BIOLOGY 2017; 164:30. [PMID: 28133395 PMCID: PMC5236075 DOI: 10.1007/s00227-016-3055-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/05/2016] [Indexed: 06/06/2023]
Abstract
Many marine megavertebrate taxa, including sea turtles, disperse widely from their hatching or birthing locations but display natal homing as adults. We used flipper tagging, satellite tracking and genetics to identify the origin of loggerhead turtles living in Amvrakikos Gulf, Greece. This location has been identified as hosting regionally important numbers of large-juvenile to adult sized turtles that display long-term residency and/or association to the area, and also presents a male biased sex ratio for adults. A total of 20 individuals were linked to nesting areas in Greece through flipper tagging and satellite telemetry, with the majority (16) associated with Zakynthos Island. One additional female was tracked from Amvrakikos Gulf to Turkey where she likely nested. Mitochondrial DNA mixed stock analyses of turtles captured in Amvrakikos Gulf (n = 95) indicated 82% of individuals originated from Greek nesting stocks, mainly from Zakynthos Island (63%), with lesser contributions from central Turkey, Cyprus and Libya. These results suggest that the male-biased sex ratio found in Amvrakikos Gulf may be driven by the fact that males breed twice as frequently on Zakynthos, resulting in their using foraging grounds of greater proximity to the breeding site. Conservation measures in localised foraging habitats for the protection of marine vertebrates, such as sea turtles, may have positive impacts on several disparate breeding stocks and the use of multiple methods to determine source populations can indicate the relative effectiveness of these measures.
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Affiliation(s)
- ALan F. Rees
- ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, 104 32 Athens, Greece
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Carlos Carreras
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
- Department of Genetics, Microbiology and Statistics and IRBio, University of Barcelona, Av.Diagonal 643, 08028 Barcelona, Spain
| | - Annette C. Broderick
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Dimitris Margaritoulis
- ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, 104 32 Athens, Greece
| | - Thomas B. Stringell
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - Brendan J. Godley
- Marine Turtle Research Group, Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
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Turner Tomaszewicz CN, Seminoff JA, Peckham SH, Avens L, Kurle CM. Intrapopulation variability in the timing of ontogenetic habitat shifts in sea turtles revealed using δ 15 N values from bone growth rings. J Anim Ecol 2017; 86:694-704. [PMID: 28075017 DOI: 10.1111/1365-2656.12618] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/24/2016] [Indexed: 11/29/2022]
Abstract
Determining location and timing of ontogenetic shifts in the habitat use of highly migratory species, along with possible intrapopulation variation in these shifts, is essential for understanding mechanisms driving alternate life histories and assessing overall population trends. Measuring variations in multi-year habitat-use patterns is especially difficult for remote oceanic species. To investigate the potential for differential habitat use among migratory marine vertebrates, we measured the naturally occurring stable nitrogen isotope (δ15 N) patterns that differentiate distinct ocean regions to create a 'regional isotope characterization', analysed the δ15 N values from annual bone growth layer rings from dead-stranded animals, and then combined the bone and regional isotope data to track individual animal movement patterns over multiple years. We used humeri from juvenile North Pacific loggerhead turtles (Caretta caretta), animals that undergo long migrations across the North Pacific Ocean (NPO), using multiple discrete regions as they develop to adulthood. Typical of many migratory marine species, ontogenetic changes in habitat use throughout their decades-long juvenile stage is poorly understood, but each potential habitat has unique foraging opportunities and spatially explicit natural and anthropogenic threats that could affect key life-history parameters. We found a bimodal size/age distribution in the timing that juveniles underwent an ontogenetic habitat shift from the oceanic central North Pacific (CNP) to the neritic east Pacific region near the Baja California Peninsula (BCP) (42·7 ± 7·2 vs. 68·3 ± 3·4 cm carapace length, 7·5 ± 2·7 vs. 15·6 ± 1·7 years). Important to the survival of this population, these disparate habitats differ considerably in their food availability, energy requirements and threats, and these differences can influence life-history parameters such as growth, survival and future fecundity. This is the first evidence of alternative ontogenetic shifts and habitat-use patterns for juveniles foraging in the eastern NPO. We combine two techniques, skeletochronology and stable isotope analysis, to reconstruct multi-year habitat-use patterns of a remote migratory species, linked to estimated ages and body sizes of individuals, to reveal variable ontogeny during the juvenile life stage that could drive alternate life histories and that has the potential to illuminate the migration patterns for other species with accretionary tissues.
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Affiliation(s)
- Calandra N Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, La Jolla, CA, 92093, USA.,Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, CA, 92037, USA
| | - Jeffrey A Seminoff
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, CA, 92037, USA
| | - S Hoyt Peckham
- Center for Ocean Solutions, Stanford University, Pacific Grove, CA, 93950, USA
| | - Larisa Avens
- Southeast Fisheries Science Center, NOAA-National Marine Fisheries Service, Beaufort, NC, 28516, USA
| | - Carolyn M Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, La Jolla, CA, 92093, USA
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19
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Rees AF, Alfaro-Shigueto J, Barata PCR, Bjorndal KA, Bolten AB, Bourjea J, Broderick AC, Campbell LM, Cardona L, Carreras C, Casale P, Ceriani SA, Dutton PH, Eguchi T, Formia A, Fuentes MMPB, Fuller WJ, Girondot M, Godfrey MH, Hamann M, Hart KM, Hays GC, Hochscheid S, Kaska Y, Jensen MP, Mangel JC, Mortimer JA, Naro-Maciel E, Ng CKY, Nichols WJ, Phillott AD, Reina RD, Revuelta O, Schofield G, Seminoff JA, Shanker K, Tomás J, van de Merwe JP, Van Houtan KS, Vander Zanden HB, Wallace BP, Wedemeyer-Strombel KR, Work TM, Godley BJ. Are we working towards global research priorities for management and conservation of sea turtles? ENDANGER SPECIES RES 2016. [DOI: 10.3354/esr00801] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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20
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Strindberg S, Coleman RA, Burns Perez VR, Campbell CL, Majil I, Gibson J. In-water assessments of sea turtles at Glover’s Reef Atoll, Belize. ENDANGER SPECIES RES 2016. [DOI: 10.3354/esr00765] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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21
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Kedzuf S, Salmon M. Do Marine Turtles Use Odors to Locate Foraging Hotspots in the Open Ocean? CHELONIAN CONSERVATION AND BIOLOGY 2016. [DOI: 10.2744/ccb-1183.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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22
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Turner Tomaszewicz CN, Seminoff JA, Avens L, Kurle CM. Methods for sampling sequential annual bone growth layers for stable isotope analysis. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12522] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Calandra N. Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior and Evolution Section University of California San Diego La Jolla CA 92093‐0116 USA
- Southwest Fisheries Science Center NOAA, National Marine Fisheries Service La Jolla CA 92037 USA
| | - Jeffrey A. Seminoff
- Southwest Fisheries Science Center NOAA, National Marine Fisheries Service La Jolla CA 92037 USA
| | - Larisa Avens
- Southeast Fisheries Science Center NOAA, National Marine Fisheries Service Beaufort NC 28516 USA
| | - Carolyn M. Kurle
- Division of Biological Sciences, Ecology, Behavior and Evolution Section University of California San Diego La Jolla CA 92093‐0116 USA
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23
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Briscoe DK, Parker DM, Bograd S, Hazen E, Scales K, Balazs GH, Kurita M, Saito T, Okamoto H, Rice M, Polovina JJ, Crowder LB. Multi-year tracking reveals extensive pelagic phase of juvenile loggerhead sea turtles in the North Pacific. MOVEMENT ECOLOGY 2016; 4:23. [PMID: 27729983 PMCID: PMC5048666 DOI: 10.1186/s40462-016-0087-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 09/13/2016] [Indexed: 05/04/2023]
Abstract
BACKGROUND The juvenile stage of loggerhead sea turtles (Caretta caretta) can last for decades. In the North Pacific Ocean, much is known about their seasonal movements in relation to pelagic habitat, yet understanding their multi-year, basin-scale movements has proven more difficult. Here, we categorize the large-scale movements of 231 turtles satellite tracked from 1997 to 2013 and explore the influence of biological and environmental drivers on basin-scale movement. RESULTS Results show high residency of juvenile loggerheads within the Central North Pacific and a moderate influence of the Earth's magnetic field, but no real-time environmental driver to explain migratory behavior. CONCLUSIONS We suggest the Central North Pacific acts as important developmental foraging grounds for young juvenile loggerhead sea turtles, rather than just a migratory corridor. We propose several hypotheses that may influence the connectivity between western and eastern juvenile loggerhead foraging grounds in the North Pacific Ocean.
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Affiliation(s)
- D. K. Briscoe
- Hopkins Marine Station, Stanford University, Pacific Grove, CA USA
| | - D. M. Parker
- Joint Institute for Marine and Atmospheric Research, National Oceanic and Atmospheric Administration, Newport, OR USA
| | - S. Bograd
- Environmental Research Division, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Southwest Fisheries Science Center, Monterey, CA USA
| | - E. Hazen
- Environmental Research Division, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Southwest Fisheries Science Center, Monterey, CA USA
| | - K. Scales
- Environmental Research Division, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Southwest Fisheries Science Center, Monterey, CA USA
| | - G. H. Balazs
- National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Pacific Islands Fisheries Science Center, Honolulu, HI USA
| | - M. Kurita
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya, 455-0033 Japan
| | - T. Saito
- Usa Marine Biological Institute, Kochi University, Usa Tosa, Kochi, 781-1164 Japan
| | - H. Okamoto
- Port of Nagoya Public Aquarium, Minato-ku, Nagoya, 455-0033 Japan
| | - M. Rice
- Hawaii Preparatory Academy, 65-1692 Kohala Mt. Rd. Kamuela, Hawaii, 96743 USA
| | - J. J. Polovina
- National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Pacific Islands Fisheries Science Center, Honolulu, HI USA
| | - L. B. Crowder
- Hopkins Marine Station, Stanford University, Pacific Grove, CA USA
- Center for Ocean Solutions, Stanford University, Monterey, CA USA
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24
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Tomaszewicz CNT, Seminoff JA, Avens L, Goshe LR, Peckham SH, Rguez-Baron JM, Bickerman K, Kurle CM. Age and residency duration of loggerhead turtles at a North Pacific bycatch hotspot using skeletochronology. BIOLOGICAL CONSERVATION 2015; 186:134-142. [PMID: 25848136 PMCID: PMC4384431 DOI: 10.1016/j.biocon.2015.03.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For migratory marine animals, like sea turtles, effective conservation can be challenging because key demographic information such as duration of life stages and exposure to spatially explicit threats in different habitats are often unknown. In the eastern Pacific near the Baja California Peninsula (BCP), Mexico, tens of thousands of endangered North Pacific loggerhead sea turtles (Caretta caretta) concentrate at a foraging area known to have high rates of fishery bycatch. Because stage survivorship of loggerheads in the BCP will vary significantly depending on the number of years spent in this region, we applied skeletochronology to empirically estimate residency duration in this loggerhead hotspot. The observed age distribution obtained from skeletochronology analysis of 146 dead-stranded loggerheads ranged from three to 24 years old, suggesting a BCP residency of >20 years. Given the maximum estimated age and a one-year migration to western Pacific nesting beaches, we infer age-at-maturation for BCP loggerheads at ~25 years old. We also examine survivorship at varying BCP residency durations by applying our findings to current annual mortality estimates. Predicted survivorship of loggerheads spending over 20 years in this BCP foraging habitat is less than 10%, and given that ~43,000 loggerhead turtles forage here, a significant number of turtles are at extreme risk in this region. This is the first empirical evidence supporting estimated age-at-maturation for BCP North Pacific loggerheads, and the first estimates of BCP stage survivorship. Our findings emphasize the urgent need for continued and effective international conservation efforts to minimize bycatch of this endangered species.
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Affiliation(s)
- Calandra N. Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, CA 92093-0116, USA
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, California 92037, USA
- Corresponding Author: CTT, , 858-334-2842 Address: University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0116
| | - Jeffrey A. Seminoff
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, California 92037, USA
| | - Larisa Avens
- Southeast Fisheries Science Center, NOAA, National Marine Fisheries Service, Beaufort, North Carolina 28516, USA
| | - Lisa R. Goshe
- Southeast Fisheries Science Center, NOAA, National Marine Fisheries Service, Beaufort, North Carolina 28516, USA
| | - S. Hoyt Peckham
- Center for Ocean Solutions, Stanford University, Pacific Grove, California 93940, USA
| | - Juan M. Rguez-Baron
- Marine Biology Department, Universidad Autonoma de Baja California Sur., La Paz, Baja California Sur, Mexico
| | - Kalyn Bickerman
- School of Biology and Ecology, University of Maine, Orono, Maine 04469, USA
| | - Carolyn M. Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, CA 92093-0116, USA
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