School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, 6150, Australia.
School of Biological Sciences and Oceans Institute, University of Western Australia, Crawley, Western Australia, 6009, Australia.
Sci Rep. 2017 Jul 10;7(1):4995. doi: 10.1038/s41598-017-05189-0.
The incidental capture of wildlife in fishing gear presents a global conservation challenge. As a baseline to inform assessments of the impact of bycatch on bottlenose dolphins (Tursiops truncatus) interacting with an Australian trawl fishery, we conducted an aerial survey to estimate dolphin abundance across the fishery. Concurrently, we carried out boat-based dolphin photo-identification to assess short-term fidelity to foraging around trawlers, and used photographic and genetic data to infer longer-term fidelity to the fishery. We estimated abundance at ≈ 2,300 dolphins (95% CI = 1,247-4,214) over the ≈ 25,880-km fishery. Mark-recapture estimates yielded 226 (SE = 38.5) dolphins associating with one trawler and some individuals photographed up to seven times over 12 capture periods. Moreover, photographic and genetic re-sampling over three years confirmed that some individuals show long-term fidelity to trawler-associated foraging. Our study presents the first abundance estimate for any Australian pelagic dolphin community and documents individuals associating with trawlers over days, months and years. Without trend data or correction factors for dolphin availability, the impact of bycatch on this dolphin population's conservation status remains unknown. These results should be taken into account by management agencies assessing the impact of fisheries-related mortality on this protected species.
渔具偶然捕获野生动物是一个全球性的保护挑战。作为评估兼捕对与澳大利亚拖网渔业相互作用的宽吻海豚（Tursiops truncatus）影响的基线，我们进行了航空调查，以估算该渔业中海豚的数量。同时，我们进行了基于船只的海豚照片识别，以评估海豚在拖网渔船周围觅食的短期忠诚度，并使用照片和遗传数据推断其对渔业的长期忠诚度。我们估计在约 25,880 公里的渔业中，海豚的数量约为 2300 只（95%置信区间 = 1247-4214）。标记-重捕估计得出 226 只（SE = 38.5）海豚与一艘拖网渔船有关，一些个体在 12 个捕获期内被拍到多达 7 次。此外，在三年的时间里，通过照片和遗传再抽样确认了一些个体对与拖网渔船相关的觅食具有长期忠诚度。我们的研究首次对任何澳大利亚远洋海豚群体进行了数量估计，并记录了个体与拖网渔船的持续多天、数月和数年的关联。由于缺乏兼捕对该海豚种群保护状况影响的趋势数据或海豚可用性的校正因素，其影响仍然未知。这些结果应被负责评估渔业相关死亡率对该受保护物种影响的管理机构考虑在内。
