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Fernando D, Stewart JD. High bycatch rates of manta and devil rays in the "small-scale" artisanal fisheries of Sri Lanka. PeerJ 2021; 9:e11994. [PMID: 34589295 PMCID: PMC8434810 DOI: 10.7717/peerj.11994] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/27/2021] [Indexed: 01/05/2023] Open
Abstract
Background Expanding fisheries in developing nations like Sri Lanka have a significant impact on threatened marine species such as elasmobranchs. Manta and devil (mobulid) rays have some of the most conservative life history strategies of any elasmobranch, and even low to moderate levels of bycatch from gillnet fisheries may lead to significant population declines. A lack of information on life history, demographics, population trends, and fisheries impacts hinders effective management measures for these species. Method We report on mobulid fishery landings over nine years between 2011 and 2020 across 38 landing sites in Sri Lanka. We collected data on catch numbers, body sizes, sex, and maturity status for five mobulid species. We used a Bayesian state-space model to estimate monthly country-wide catch rates and total annual landings of mobulid rays. We used catch curve analyses to estimate total mortality for Mobula mobular, and evaluated trends in recorded body sizes across the study period for M. mobular, M. birostris, M. tarapacana and M. thurstoni. Results We find that catch rates have declined an order of magnitude for all species across the study period, and that total annual captures of mobulid rays by the Sri Lankan artisanal fishing fleet exceed the estimated annual captures of mobulids in all global, industrial purse seine fisheries combined. Catch curve analyses suggest that M. mobular is being fished at rates far above the species' intrinsic population growth rate, and the average sizes of all mobulids in the fishery except for M. birostris are declining. Collectively, these findings suggest overfishing of mobulid ray populations in the northern Indian Ocean by Sri Lankan artisanal fisheries. We recommend strengthening the management of these species through improved implementation of CITES, CMS, and regional fisheries management actions. In addition, we report on the demographic characteristics of mobulids landed in Sri Lanka and provide the first record of M. eregoodoo in the country.
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Affiliation(s)
- Daniel Fernando
- Blue Resources Trust, Colombo, Sri Lanka.,The Manta Trust, Dorchester, United Kingdom.,Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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2
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Barbini SA, Sabadin DE, Román JM, Scarabotti PA, Lucifora LO. Age, growth, maturity and extinction risk of an exploited and endangered skate, Atlantoraja castelnaui, from off Uruguay and northern Argentina. JOURNAL OF FISH BIOLOGY 2021; 99:1328-1340. [PMID: 34181283 DOI: 10.1111/jfb.14839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/19/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
The spotback skate Atlantoraja castelnaui (Arhynchobatidae) is a large and threatened skate species subjected to fishing pressure, endemic to the Southwest Atlantic that occurs from Rio de Janeiro, Brazil, to San Jorge Gulf, Argentina. The age, growth, age at maturity and the maximum intrinsic rate of population increase rmax of A. castelnaui were studied using 152 specimens collected from off Uruguay and north Argentina (35°-42° S), between June 2013 and February 2020. Vertebrae from 143 individuals were used for ageing (females: n = 83, size range 404-1300 mm total length, TL; males: n = 60, size range 400-1270 mm TL). Maximum ages determined for females and males were 30 and 28 years, respectively. To fit growth models, non-linear and Bayesian estimation approaches were considered. For the first approach, a set of four candidate growth (size-at-age) models were fitted: three-parameter von Bertalanffy, two-parameter von Bertalanffy with fixed L0 , Gompertz and Logistic. In the second approach, von Bertalanffy, Gompertz and Logistic were fitted. For non-linear estimation, model selection indicated that the entire set of candidate growth models were supported by the data. The von Bertalanffy was selected as the best model for Bayesian estimation. There were no differences in growth between sexes. For the sexes combined, the von Bertalanffy growth model by Bayesian method was considered the most adequate to describe the growth of A. castelnaui (growth mean parameters ± S.D.: L∞ = 1210.29 ± 40.68 mm; k = 0.12 ± 0.01 years-1 ; L0 = 179.20 ± 11.62 mm). The age at maturity was estimated at 16.21 and 14.04 years for females and males, respectively. The maximum intrinsic rate of population increase rmax was estimated as 0.252 years-1 . Life-history traits and rmax provided in the present study suggest that this species has a relatively low productivity and may be vulnerable to an intense fishing pressure.
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Affiliation(s)
- Santiago A Barbini
- Biología de Peces, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - David E Sabadin
- Biología de Peces, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Jorge M Román
- Biología de Peces, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Pablo A Scarabotti
- Instituto Nacional de Limnología, Universidad Nacional del Litoral, CONICET, Santa Fe, Argentina
| | - Luis O Lucifora
- Instituto Nacional de Limnología, Universidad Nacional del Litoral, CONICET, Santa Fe, Argentina
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3
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Bucair N, Francini-Filho RB, Almerón-Souza F, Luiz OJ. Underestimated threats to manta rays in Brazil: Primacies to support conservation strategies. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01753] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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4
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Temple AJ, Stead SM, Jiddawi N, Wambiji N, Dulvy NK, Barrowclift E, Berggren P. Life-history, exploitation and extinction risk of the data-poor Baraka's whipray (Maculabatis ambigua) in small-scale tropical fisheries. JOURNAL OF FISH BIOLOGY 2020; 97:708-719. [PMID: 32524614 DOI: 10.1111/jfb.14425] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/08/2020] [Accepted: 06/08/2020] [Indexed: 06/11/2023]
Abstract
The Baraka's whipray (Maculabatis ambigua) is a major constituent of small-scale fisheries catch in the south-western Indian Ocean. Despite this, little is known of its life-history or exploitation status. We provide the first estimates of crucial life-history parameters and the maximum intrinsic population growth rate rmax , using specimens collected from small-scale fisheries landings in Kenya, Zanzibar and Madagascar (with northern Madagascar representing a range extension for this species). We assess the relative risk of overexploitation by combining rmax with estimates of total Z, fishing F, and natural M mortality, and an estimate of the exploitation ratio E. The data indicate that Baraka's whipray is a medium-sized, fast-growing, early maturing species, with a relatively long lifespan. This results in a high rmax relative to many other elasmobranchs, which when combined with estimates of F suggests that the species is not at imminent risk of extinction. Yet, estimates of exploitation ratio E indicate likely overfishing for the species, with full recruitment to the fishery being post-maturation and exploitation occurring across a broad range of age and size classes. Thus, Baraka's whipray is unlikely to be biologically sustainable in the face of current fisheries pressures. This paper makes an important contribution to filling the gap in available data and is a step towards developing evidence-based fisheries management for this species. Further, it demonstrates a simple and widely applicable framework for assessment of data-poor elasmobranch exploitation status and extinction risk.
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Affiliation(s)
- Andrew J Temple
- School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, UK
| | - Selina M Stead
- School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, UK
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - Narriman Jiddawi
- Institute of Marine Sciences, Dar es Salaam University, Dar es Salaam, Tanzania
- Institute of Fisheries Research Zanzibar, Ministry of Agriculture, Natural Resources, Livestock and Fisheries, Stone Town, Zanzibar, Tanzania
| | - Nina Wambiji
- Kenya Marine and Fisheries Research Institute, Mombasa, Kenya
| | - Nicholas K Dulvy
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Ellen Barrowclift
- School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, UK
| | - Per Berggren
- School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, UK
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5
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Chen Y, Shertzer KW, Viehman TS. Spatio‐temporal dynamics of the threatened elkhorn coral
Acropora palmata
: Implications for conservation. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Yi‐Hsiu Chen
- National Academies of Sciences Engineering and Medicine National Research Council Washington DC USA
- National Centers for Costal Ocean Science NOAA National Ocean Service Beaufort NC USA
| | - Kyle W. Shertzer
- Southeast Fisheries Science Center National Marine Fisheries Service Beaufort NC USA
| | - T. Shay Viehman
- National Centers for Costal Ocean Science NOAA National Ocean Service Beaufort NC USA
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Derrick DH, Cheok J, Dulvy NK. Spatially congruent sites of importance for global shark and ray biodiversity. PLoS One 2020; 15:e0235559. [PMID: 32628691 PMCID: PMC7337351 DOI: 10.1371/journal.pone.0235559] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 06/17/2020] [Indexed: 11/21/2022] Open
Abstract
Many important areas identified for conservation priorities focus on areas of high species richness, however, it is unclear whether these areas change depending on what aspect of richness is considered (e.g. evolutionary distinctiveness, endemicity, or threatened species). Furthermore, little is known of the extent of spatial congruency between biodiversity measures in the marine realm. Here, we used the distribution maps of all known marine sharks, rays, and chimaeras (class Chondrichthyes) to examine the extent of spatial congruency across the hotspots of three measures of species richness: total number of species, evolutionarily distinct species, and endemic species. We assessed the spatial congruency between hotspots considering all species, as well as on the subset of the threatened species only. We consider three definitions of hotspot (2.5%, 5%, and 10% of cells with the highest numbers of species) and three levels of spatial resolution (1°, 4°, and 8° grid cells). Overall, we found low congruency among all three measures of species richness, with the threatened species comprising a smaller subset of the overall species patterns irrespective of hotspot definition. Areas of congruency at 1° and 5% richest cells contain over half (64%) of all sharks and rays and occurred off the coasts of: (1) Northern Mexico Gulf of California, (2) USA Gulf of Mexico, (3) Ecuador, (4) Uruguay and southern Brazil, (5) South Africa, southern Mozambique, and southern Namibia, (6) Japan, Taiwan, and parts of southern China, and (7) eastern and western Australia. Coarsening resolution increases congruency two-fold for all species but remains relatively low for threatened measures, and geographic locations of congruent areas also change. Finally, for pairwise comparisons of biodiversity measures, evolutionarily distinct species richness had the highest overlap with total species richness regardless of resolution or definition of hotspot. We suggest that focusing conservation attention solely on areas of high total species richness will not necessarily contribute efforts towards species that are most at risk, nor will it protect other important dimensions of species richness.
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Affiliation(s)
- Danielle H. Derrick
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail:
| | - Jessica Cheok
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Nicholas K. Dulvy
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, British Columbia, Canada
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7
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Population productivity of shovelnose rays: Inferring the potential for recovery. PLoS One 2019; 14:e0225183. [PMID: 31751369 PMCID: PMC6872150 DOI: 10.1371/journal.pone.0225183] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 10/30/2019] [Indexed: 11/22/2022] Open
Abstract
There is recent evidence of widespread declines of shovelnose ray populations (Order Rhinopristiformes) in heavily fished regions. These declines, which are likely driven by high demand for their fins in Asian markets, raises concern about their risk of over-exploitation and extinction. Using life-history theory and incorporating uncertainty into a modified Euler-Lotka model, the maximum intrinsic rates of population increase (rmax) were estimated for nine species from four families of Rhinopristiformes, using four different natural mortality estimators. Estimates of mean rmax, across the different natural mortality methods, varied from 0.03 to 0.59 year-1 among the nine species, but generally increased with increasing maximum size. Comparing these estimates to rmax values for other species of chondrichthyans, the species Rhynchobatus australiae, Glaucostegus typus, and Glaucostegus cemiculus were relatively productive, while most species from Rhinobatidae and Trygonorrhinidae had relatively low rmax values. If the demand for their high-value products can be addressed then population recovery for some species is likely possible, but will vary depending on the species.
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8
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Lezama-Ochoa N, Hall MA, Pennino MG, Stewart JD, López J, Murua H. Environmental characteristics associated with the presence of the Spinetail devil ray (Mobula mobular) in the eastern tropical Pacific. PLoS One 2019; 14:e0220854. [PMID: 31390369 PMCID: PMC6685623 DOI: 10.1371/journal.pone.0220854] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 07/24/2019] [Indexed: 12/28/2022] Open
Abstract
In the eastern Pacific Ocean, the tropical tuna purse-seine fishery incidentally captures high numbers of five mobulid bycatch species; all of which are classified as mortalities by the Inter-American Tropical Tuna Commission due to uncertainties in post-release mortality rates. To date, the factors (operational or environmental) leading to the capture of these species by the fishery have not been well studied. Here, we developed Generalized Additive Models for fisheries observer data to analyze the relationships between the presence/absence of Mobula mobular bycatch and oceanographic conditions, the spatial and temporal variability in fishing location, and the set type (associated with dolphins, free-swimming tuna schools or floating objects). Our results suggest that chlorophyll concentration and sea surface height are the most important variables to describe the presence of M. mobular in conjunction with geographic location (latitude and longitude) and set type. Presence of the species was predicted in waters with chlorophyll concentrations between 0.5–1 mg·m-3 and with sea surface height values close to 0; which indicates direct relationships with productive upwelling systems. Seasonally, M. mobular was observed more frequently during December-January and August-September. We also found the highest probability of presence observed in School sets, followed by Dolphin sets. Three areas were observed as important hotspots: the area close to the coastal upwelling of northern Peru, the area west to Islands Colon Archipelago (Galapagos) and the area close to the Costa Rica Dome. This information is crucial to identify the mobulids habitat and hotspots that could be managed and protected under dynamic spatial management measures to reduce the mortality of mobulid rays in the eastern Pacific purse-seine fishery and, hence, ensure the sustainability of the populations of these iconic species.
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Affiliation(s)
- Nerea Lezama-Ochoa
- Inter-American Tropical Tuna Commission, Bycatch Program, La Jolla, San Diego, CA, United States of America
- AZTI-Tecnalia, Marine Research Division, Pasaia, Spain
- * E-mail:
| | - Martin A. Hall
- Inter-American Tropical Tuna Commission, Bycatch Program, La Jolla, San Diego, CA, United States of America
| | | | - Joshua D. Stewart
- Scripps Institution of Oceanography, La Jolla, San Diego, CA, United States of America
- The Manta Trust, Dorchester, Dorset, United Kingdom
| | - Jon López
- Inter-American Tropical Tuna Commission, Bycatch Program, La Jolla, San Diego, CA, United States of America
| | - Hilario Murua
- AZTI-Tecnalia, Marine Research Division, Pasaia, Spain
- International Seafood Sustainability Foundation (ISSF), Washington, DC, United States of America
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9
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Baje L, Smart JJ, Chin A, White WT, Simpfendorfer CA. Age, growth and maturity of the Australian sharpnose shark Rhizoprionodon taylori from the Gulf of Papua. PLoS One 2018; 13:e0206581. [PMID: 30379918 PMCID: PMC6209343 DOI: 10.1371/journal.pone.0206581] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 10/16/2018] [Indexed: 11/19/2022] Open
Abstract
Coastal sharks with small body sizes may be among the most productive species of chondrichthyans. The Australian sharpnose shark (Rhizoprionodon taylori) is one of the most productive members of this group based on work in northern and eastern Australia. However, life history information throughout the remainder of its range is lacking. To address this knowledge gap, the age, growth and maturity of R. taylori caught in the Gulf of Papua prawn trawl fishery in Papua New Guinea, were studied. One hundred and eighty six individuals, comprising 131 females (31-66 cm TL) and 55 males (31-53 cm TL) were aged using vertebral analysis and growth was modelled using a multi-model approach. The lack of small individuals close to the size at birth made fitting of growth curves more difficult, two methods (fixed length at birth and additional zero aged individuals) accounting for this were trialled. The von Bertalanffy growth model provided the best fit to the data when used with a fixed length-at-birth (L0 = 26 cm TL). Males (L∞ = 46 cm TL, k = 3.69 yr-1, L50 = 41.7 cm TL and A50 = 0.5 years) grew at a faster rate and matured at smaller sizes and younger ages than females (L∞ = 58 cm TL, k = 1.98 yr-1, L5o = 47.0 cm TL and A50 = 0.93 years). However, none of the methods to account for the lack of small individuals fully accounted for this phenomenon, and hence the results remain uncertain. Despite this, the results reaffirm the rapid growth of this species and suggest that the Gulf of Papua population may grow at a faster rate than Australian populations. Rhizoprionodon taylori is possibly well placed to withstand current fishing pressure despite being a common bycatch species in the Gulf of Papua prawn trawl fishery. However, further research needs to be undertaken to estimate other key life history parameters to fully assess the population status of this exploited shark species and its vulnerability to fishing in the Gulf of Papua.
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Affiliation(s)
- Leontine Baje
- National Fisheries Authority, National Capital District, Port Moresby, Papua New Guinea
- Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
- * E-mail:
| | - Jonathan J. Smart
- Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
- SARDI Aquatic Sciences, Adelaide, South Australia
| | - Andrew Chin
- Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | - William T. White
- CSIRO Oceans & Atmosphere, Hobart, Tasmania, Australia
- CSIRO Australian National Fish Collection, National Research Collections Australia, Hobart, Tasmania, Australia
| | - Colin A. Simpfendorfer
- Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
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10
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Kacev D, Sippel TJ, Kinney MJ, Pardo SA, Mull CG. An Introduction to Modelling Abundance and Life History Parameters in Shark Populations. ADVANCES IN MARINE BIOLOGY 2017; 78:45-87. [PMID: 29056143 DOI: 10.1016/bs.amb.2017.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Elasmobranchs play critically important ecological roles throughout the world's oceans, yet in many cases, their slow life histories and interactions with fisheries makes them particularly susceptible to exploitation. Management for these species requires robust scientific input, and mathematical models are the backbone of science-based management. In this chapter, we provide an introductory overview of the use of mathematical models to estimate shark abundance. First, we discuss life history models that are used to understand the basic biology of elasmobranchs. Second, we cover population dynamics models, which are used to make inferences regarding population trend, size, and risk of extinction. Finally, we provide examples of applied models used to assess the status of elasmobranchs in the Northeast Pacific Ocean to guide management for these species. This chapter is not a comprehensive review of quantitative methods, but rather introduces various mathematical tools in fisheries management, with a focus on shark management in the Northeast Pacific Ocean.
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Affiliation(s)
- Dovi Kacev
- Ocean Associates, Inc., Arlington, VA, United States.
| | | | | | - Sebastián A Pardo
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, BC, Canada
| | - Christopher G Mull
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, BC, Canada
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11
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Ebert DA, Bigman JS, Lawson JM. Biodiversity, Life History, and Conservation of Northeastern Pacific Chondrichthyans. ADVANCES IN MARINE BIOLOGY 2017; 77:9-78. [PMID: 28882216 DOI: 10.1016/bs.amb.2017.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The sharks, batoids, and chimaeras, collectively the class Chondrichthyes, are one of the most successful groups of fishes, with over 1250 species globally. Recent taxonomic revisions have increased their diversity by about 20% over the past 17 years (2000-2016). The Northeast Pacific Ocean is one of the top 20 most diverse regions/countries on the globe with 77 chondrichthyan species, a number less than a quarter that of the most species-rich area (Australia) but that has increased by 10% since 2000 to include three new species (two skates and a chimaera). In this chapter we discuss the species richness of chondrichthyans occurring in the Northeast Pacific Ocean, characterize their life histories, briefly review several fisheries, and summarize the conservation status of those chondrichthyans occurring in the region. Detailed descriptions and evaluations of fisheries can be found in Chapter 7 of AMB Volume 78.
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Affiliation(s)
- David A Ebert
- Pacific Shark Research Center, Moss Landing Marine Laboratories, Moss Landing, CA, United States.
| | - Jennifer S Bigman
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, BC, Canada
| | - Julia M Lawson
- Earth to Ocean Research Group, Simon Fraser University, Burnaby, BC, Canada
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12
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Steinke D, Bernard AM, Horn RL, Hilton P, Hanner R, Shivji MS. DNA analysis of traded shark fins and mobulid gill plates reveals a high proportion of species of conservation concern. Sci Rep 2017; 7:9505. [PMID: 28842669 PMCID: PMC5573315 DOI: 10.1038/s41598-017-10123-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/04/2017] [Indexed: 12/05/2022] Open
Abstract
Continuously increasing demand for plant and animal products causes unsustainable depletion of biological resources. It is estimated that one-quarter of sharks and rays are threatened worldwide and although the global fin trade is widely recognized as a major driver, demand for meat, liver oil, and gill plates also represents a significant threat. This study used DNA barcoding and 16 S rRNA sequencing as a method to identify shark and ray species from dried fins and gill plates, obtained in Canada, China, and Sri Lanka. 129 fins and gill plates were analysed and searches on BOLD produced matches to 20 species of sharks and five species of rays or – in two cases – to a species pair. Twelve of the species found are listed or have been approved for listing in 2017 in the appendices of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES), including the whale shark (Rhincodon typus), which was surprisingly found among both shark fin and gill plate samples. More than half of identified species fall under the IUCN Red List categories ‘Endangered’ and ‘Vulnerable’, raising further concerns about the impacts of this trade on the sustainability of these low productivity species.
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Affiliation(s)
- Dirk Steinke
- Centre for Biodiversity Genomics, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada.
| | - Andrea M Bernard
- Save Our Seas Shark Research Center USA and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA.,Guy Harvey Research Institute and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
| | - Rebekah L Horn
- Save Our Seas Shark Research Center USA and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA.,Guy Harvey Research Institute and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
| | | | - Robert Hanner
- Biodiversity Institute of Ontario, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
| | - Mahmood S Shivji
- Save Our Seas Shark Research Center USA and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA. .,Guy Harvey Research Institute and Department of Biological Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA.
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13
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Rohner CA, Burgess KB, Rambahiniarison JM, Stewart JD, Ponzo A, Richardson AJ. Mobulid rays feed on euphausiids in the Bohol Sea. ROYAL SOCIETY OPEN SCIENCE 2017; 4:161060. [PMID: 28572998 PMCID: PMC5451799 DOI: 10.1098/rsos.161060] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 04/25/2017] [Indexed: 05/13/2023]
Abstract
Mobulid rays have a conservative life history and are caught in direct fisheries and as by-catch. Their subsequent vulnerability to overexploitation has recently been recognized, but fisheries management can be ineffective if it ignores habitat and prey preferences and other trophic interactions of the target species. Here, we assessed the feeding ecology of four mobulids (Manta birostris, Mobula tarapacana, M. japanica, M. thurstoni) in the Bohol Sea, Philippines, using stomach contents analysis of fisheries specimens landed between November and May in 2013-2015. We show that the mobulids feed heavily on euphausiid krill while they are in the area for approximately six months of the year. We found almost no trophic separation among the mobulid species, with Euphausia diomedeae as the major prey item for all species, recorded in 81 of 89 total stomachs (91%). Mobula japanica and M. thurstoni almost exclusively had this krill in their stomach, while M. tarapacana had a squid and fish, and Ma. birostris had myctophid fishes and copepods in their stomachs in addition to E. diomedeae. This krill was larger than prey for other planktivorous elasmobranchs elsewhere and contributed a mean of 61 364 kcal per stomach (±105 032 kcal s.e., range = 0-631 167 kcal). Our results show that vertically migrating mesopelagic species can be an important food resource for large filter feeders living in tropical seas with oligotrophic surface waters. Given the conservative life history of mobulid rays, the identification of common foraging grounds that overlap with fishing activity could be used to inform future fishing effort.
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Affiliation(s)
| | - Katherine B. Burgess
- Marine Megafauna Foundation, Praia do Tofo, Inhambane, Mozambique
- Shark and Ray Research Group, School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Joshua M. Rambahiniarison
- Large Marine Vertebrates Research Institute Philippines, Cagulada Compound, Tejero, Jagna, 6308 Bohol, Philippines
| | - Joshua D. Stewart
- Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive., La Jolla, CA 92093, USA
- The Manta Trust, Catemwood House, Corscombe, Dorchester, Dorset DT2 0NT, UK
| | - Alessandro Ponzo
- Large Marine Vertebrates Research Institute Philippines, Cagulada Compound, Tejero, Jagna, 6308 Bohol, Philippines
| | - Anthony J. Richardson
- CSIRO Oceans and Atmosphere, EcoScience Precinct, Brisbane, Queensland 4102, Australia
- Centre for Applications in Natural Resource Mathematics, School of Mathematics and Physics, University of Queensland, Brisbane, Queensland, Australia
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14
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Lawson JM, Fordham SV, O'Malley MP, Davidson LNK, Walls RHL, Heupel MR, Stevens G, Fernando D, Budziak A, Simpfendorfer CA, Ender I, Francis MP, Notarbartolo di Sciara G, Dulvy NK. Sympathy for the devil: a conservation strategy for devil and manta rays. PeerJ 2017; 5:e3027. [PMID: 28316882 PMCID: PMC5354073 DOI: 10.7717/peerj.3027] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 01/25/2017] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND International trade for luxury products, medicines, and tonics poses a threat to both terrestrial and marine wildlife. The demand for and consumption of gill plates (known as Peng Yu Sai, "Fish Gill of Mobulid Ray") from devil and manta rays (subfamily Mobulinae, collectively referred to as mobulids) poses a significant threat to these marine fishes because of their extremely low productivity. The demand for these gill plates has driven an international trade supplied by largely unmonitored and unregulated catches from target and incidental fisheries around the world. Scientific research, conservation campaigns, and legal protections for devil rays have lagged behind those for manta rays despite similar threats across all mobulids. METHODS To investigate the difference in attention given to devil rays and manta rays, we examined trends in the scientific literature and updated species distribution maps for all mobulids. Using available information on target and incidental fisheries, and gathering information on fishing and trade regulations (at international, national, and territorial levels), we examined how threats and protective measures overlap with species distribution. We then used a species conservation planning approach to develop the Global Devil and Manta Ray Conservation Strategy, specifying a vision, goals, objectives, and actions to advance the knowledge and protection of both devil and manta rays. RESULTS AND DISCUSSION Our literature review revealed that there had been nearly 2.5-times more "manta"-titled publications, than "mobula" or "devil ray"-titled publications over the past 4.5 years (January 2012-June 2016). The majority of these recent publications were reports on occurrence of mobulid species. These publications contributed to updated Area of Occupancy and Extent of Occurrence maps which showed expanded distributions for most mobulid species and overlap between the two genera. While several international protections have recently expanded to include all mobulids, there remains a greater number of national, state, and territory-level protections for manta rays compared to devil rays. We hypothesize that there are fewer scientific publications and regulatory protections for devil rays due primarily to perceptions of charisma that favour manta rays. We suggest that the well-established species conservation framework used here offers an objective solution to close this gap. To advance the goals of the conservation strategy we highlight opportunities for parity in protection and suggest solutions to help reduce target and bycatch fisheries.
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Affiliation(s)
- Julia M Lawson
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University , Burnaby , British Columbia , Canada
| | - Sonja V Fordham
- Shark Advocates International, The Ocean Foundation , Washington , D.C. , United States of America
| | - Mary P O'Malley
- WildAid, San Francisco, CA, United States of America; Manta Trust, Dorchester, Dorset, United Kingdom
| | - Lindsay N K Davidson
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University , Burnaby , British Columbia , Canada
| | - Rachel H L Walls
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University , Burnaby , British Columbia , Canada
| | - Michelle R Heupel
- Australian Institute of Marine Science , Townsville , Queensland , Australia
| | - Guy Stevens
- Manta Trust, Dorchester, Dorset, United Kingdom; Environment Department, University of York, York, United Kingdom
| | - Daniel Fernando
- Manta Trust, Dorchester, Dorset, United Kingdom; Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden; Blue Resources, Colombo, Sri Lanka
| | - Ania Budziak
- Project AWARE Foundation , Rancho Santa Margarita , CA , United States of America
| | - Colin A Simpfendorfer
- Centre for Sustainable Tropical Fisheries and Aquaculture & College of Marine and Environmental Sciences, James Cook University , Townsville , Queensland , Australia
| | - Isabel Ender
- Manta Trust , Dorchester , Dorset , United Kingdom
| | - Malcolm P Francis
- National Institute of Water and Atmospheric Research , Wellington , New Zealand
| | | | - Nicholas K Dulvy
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University , Burnaby , British Columbia , Canada
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