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Mystery of giant rays off the Gaza strip solved

Published online by Cambridge University Press:  26 September 2013

Lydie I.E. Couturier ,
Michael B. Bennett  and
Anthony J. Richardson
Lydie I.E. Couturier
Affiliation:
School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia. E-mail l.couturier@uq.edu.au
Michael B. Bennett
Affiliation:
School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia. E-mail l.couturier@uq.edu.au
Anthony J. Richardson
Affiliation:
Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, Brisbane, Queensland, Australia, and Centre for Applications in Natural Resource Mathematics, School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland, Australia
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Abstract

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Type
Conservation news
Information
Oryx , Volume 47 , Issue 4 , October 2013 , pp. 480
Copyright
Copyright © Fauna & Flora International 2013 

There have been recent reports of an apparent mass stranding of dozens of the Endangered large devil ray Mobula mobular on beaches of the Gaza Strip in Palestine (Daily Mail, 27 February 2013). This species is categorized as Endangered on the IUCN Red List and is likely to be the rarest of the nine species of Mobula. There was much public and scientific speculation about the causes of the stranding. Cetaceans can strand as a result of the sonar activity of ships and submarines but there is no evidence that elasmobranchs, the group that includes Mobula, are affected by such activities. A mass stranding or disease are improbable because elasmobranchs are negatively buoyant and thus do not generally wash up on beaches. Suspicions about the cause of the deaths were raised by video footage (published online by the Daily Mail) of local people on the beach cutting out the gills, removing fins and filleting the rays, with some proficiency.

It has now been confirmed by Dr Mohammed Abudaya (United Nations Relief and Works Agency), through Professor Dani Kerem (University of Haifa) and Dr Notarbartolo-di-Sciara (Tethys Research Institute) that this was a fishery operation. Palestinian fishermen, recently allowed to fish up to 7 nautical miles offshore, noticed a large aggregation of M. mobular at the surface in an area close to the Egyptian border on 26 February 2013. They caught about 500 rays weighing 150–250 kg each. Dr Argyris Kallianiotis (National Agricultural Research Foundation) mentioned in a message sent to the Italian Society for Marine Biology that M. mobular was considered a valuable species for the local fish market. Local fishermen described the importance of the M. mobular fishery, which is conducted around the end of February each year, during a visit by FAO experts earlier this year. This species receives some protection in the Mediterranean Sea as it is listed under Annex II of the Barcelona Convention and Appendix II of the Bern Convention but the Gaza Strip is not a signatory to either of these. Waters off this region appear to be an important aggregation site for M. mobular. Our concern is that even before we understand the reasons for what appears to be a large seasonal aggregation, whether for reproduction or feeding, it could be lost.