University of Groningen Vulnerabilities and fisheries impacts Croll, Donald A.; Dewar, Heidi; Dulvy, Nicholas K.; Fernando, Daniel; Francis, Malcolm P.; Galván-Magaña, Felipe; Hall, Martin; Heinrichs, Shawn; Marshall, Andrea; Mccauley, Douglas Published in: Aquatic Conservation DOI: 10.1002/aqc.2591 IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2016 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Croll, D. A., Dewar, H., Dulvy, N. K., Fernando, D., Francis, M. P., Galván-Magaña, F., Hall, M., Heinrichs, S., Marshall, A., Mccauley, D., Newton, K. M., Notarbartolo-Di-Sciara, G., O'Malley, M., O'Sullivan, J., Poortvliet, M., Roman, M., Stevens, G., Tershy, B. R., & White, W. T. (2016). Vulnerabilities and fisheries impacts: The uncertain future of manta and devil rays. Aquatic Conservation, 26(3), 562-575. https://doi.org/10.1002/aqc.2591 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 27-09-2021 AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS Aquatic Conserv: Mar. Freshw. Ecosyst. 26: 562–575 (2016) Published online 3 November 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/aqc.2591 Vulnerabilities and fisheries impacts: the uncertain future of manta and devil rays DONALD A. CROLLa,*, HEIDI DEWARb, NICHOLAS K. DULVYc, DANIEL FERNANDOd,e, MALCOLM P. FRANCISf, FELIPE GALVÁN-MAGAÑAg, MARTIN HALLh, SHAWN HEINRICHSi, ANDREA MARSHALLj, DOUGLAS MCCAULEYk, KELLY M. NEWTONa, GIUSEPPE NOTARBARTOLO-DI-SCIARAl, MARY O’MALLEYe,m, JOHN O’SULLIVANn, MARLOES POORTVLIETa,o, MARLON ROMANh, GUY STEVENSe,p, BERNIE R. TERSHYa and WILLIAM T. WHITEq aCoastal Conservation Action Lab, University of California, Santa Cruz bSouthwest Fisheries Science Center, NOAA Fisheries cBiological Sciences, Simon Fraser University dDepartment of Biology and Environmental Science, Linnaeus University eManta Trust fFisheries, National Institute of Water and Atmospheric Research gCentro Interdisciplinario de Ciencias Marinas hInter-American Tropical Tuna Commission iBlue Sphere Media LLC jMarine Megafauna Foundation kDepartment of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara lTethys Research Institute mWildAid nMonterey Bay Aquarium oDepartment of Marine Benthic Ecology and Evolution, Centre for Ecological and Evolutionary Studies, University of Groningen pEnvironment Department, University of York qMarine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organization ABSTRACT 1. Manta and devil rays of the subfamily Mobulinae (mobulids) are rarely studied, large, pelagic elasmobranchs, with all eight of well-evaluated species listed on the IUCN Red List as threatened or near threatened. 2. Mobulids have life history characteristics (matrotrophic reproduction, extremely low fecundity, and delayed age of first reproduction) that make them exceptionally susceptible to overexploitation. 3. Targeted and bycatch mortality from fisheries is a globally important and increasing threat, and targeted fisheries are incentivized by the high value of the global trade in mobulid gill plates. 4. Fisheries bycatch of mobulids is substantial in tuna purse seine fisheries. 5. Thirteen fisheries in 12 countries specifically targeting mobulids, and 30 fisheries in 23 countries with mobulid bycatch were identified. 6. Aside from a few recently enacted national restrictions on capture, there is no comprehensive monitoring, assessment or control of mobulid fisheries or bycatch. Recent listing through the Convention on the *Correspondence to: Donald A. Croll, Coastal Conservation Action Lab, University of California, Santa Cruz, 100 Shaffer Road. Santa Cruz, CA 95060 USA. Email: [email protected] # 2016 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. THE UNCERTAIN FUTURE OF MANTA AND DEVIL RAYS 563 International Trade in Endangered Species (CITES) may benefit mobulids of the genus Manta (manta rays), but none of the mobulids in the genus Mobula (devil rays) are protected. 7. The relative economic costs of catch mitigation are minimal, particularly compared with a broad range of other, more complicated, marine conservation issues. Copyright # 2015 John Wiley & Sons, Ltd. Received 06 February 2015; Revised 28 July 2015; Accepted 13 August 2015 KEY WORDS: coastal; ocean; conservation evaluation; endangered species; fish; fishing INTRODUCTION LIFE HISTORY Marine organisms are subject to multiple Like many elasmobranchs, mobulids have anthropogenic threats (Stevens et al., 2000; Lewison K-selected life history traits including delayed, et al., 2004; Dulvy et al., 2014), and long-lived matrotrophic (ovoviparous) reproduction and low species with low fecundity (e.g. whales, seabirds, sea annual fecundity. The life history parameter that sets turtles, and sharks) are particularly vulnerable mobulids apart from other elasmobranchs and (Owens and Bennett, 2000). Pelagic elasmobranchs makes them vulnerable to overexploitation is their tend to be even more vulnerable because they have extremely low fecundity – among the lowest of all exceptionally low population growth rates, are fishes (Dulvy et al., 2014). Mobulid litter size is only often subject to targeted and bycatch in multiple one (Hoenig and Gruber, 1990, Stevens et al., 2000), fisheries, and the quantification of catch and and interbirth intervals are estimated at 1–3years management is limited or non-existent (Stevens (Notarbartolo-di-Sciara, 1988; Compagno and Last, et al., 2000; Dulvy et al., 2008, 2014). 1999; Homma et al., 1999; Marshall and Bennett, Of the pelagic elasmobranchs, the 11 species of 2010). Marshall and Bennett (2010) estimated Manta manta and devil rays, subfamily Mobulinae alfredi gestation period at 12 months with a mix of (mobulids) are among the most vulnerable. In annual and biennial pregnancies while Stevens addition to their K-selected life history traits, they (unpublished data) estimated one gestation every have been directly targeted in small-scale fisheries 5years in M. alfredi off the Maldives. Although (Notarbartolo-di-Sciara, 1988; White et al., 2006a; variable across mobulids, most annual fecundities are Rohner et al., 2013) and captured as bycatch in ~0.5 pups per year, particularly for larger species industrial fisheries (Paulin et al., 1982; White (e.g. 0.56 pregnancies per adult female per year for et al., 2006a). Between 1998 and 2009, mobulid M. alfredi;Deakoset al., 2011). landings increased more than an order of Maximum rate of mobulid population increase is magnitude (from 200 to 5000 metric tons yearÀ1) also limited by delayed age at maturation. Pups are (Ward-Paige et al., 2013). All eight of the mobulid relatively large at birth, ranging from 27 to 49% of species effectively evaluated for the IUCN Red maternal size (Notarbartolo-di-Sciara, 1988; White List are threatened (endangered or vulnerable) or et al., 2006b; Marshall et al., 2009). Information near threatened, with the remaining three listed as on age of maturation is limited, however, using data deficient (Table 1). Four species are classified unvalidated age/growth data from Cuevas-Zimbron as declining, and the population trajectory of the (2007) and size at maturity from Serrano-López remaining seven species is unknown (IUCN, 2012) (2009), Mobula japanica appear to attain sexual (Table 1). Given these concerns, a logical first step maturity at 5–6 years. Marshall et al. (2011a) to the conservation of mobulids is to evaluate their reported that M. alfredi matures at >8and>3years life history sensitivity and threats, and potential in females and males, respectively, while Clark (2010) management solutions. reported the age of maturity of M. alfredi as 3–6 years. Copyright # 2016 The Authors. Aquatic Conservation: Marine and Freshwater Aquatic Conserv: Mar. Freshw. Ecosyst. 26: 562–575 (2016) Ecosystems published by John Wiley & Sons, Ltd. 564 D. A. CROLL ET AL. Table 1. Characteristics of the family Mobulidae (Couturier et al., 2012; IUCN, 2012) Scientific IUCN Maximum common name classification Distribution Habitat size (DW) Trend Fishery Manta alfredi vulnerable Circumglobal, tropical coastal 550 cm decreasing targeted bycatch Reef manta ray and subtropical Manta birostris vulnerable Circumglobal, tropical coastal pelagic 900 cm decreasing targeted bycatch Giant manta ray and subtropical Mobula eregoodootenkee near threatened Tropical Indo-West Pacific coastal 100 cm unknown bycatch Pygmy devil ray and Northern Indian Ocean Mobula hypostoma data deficient Western