Fishery-impacted bottlenose dolphins of north-western Australia: Bycatch patterns, genetic status and abundance

摘要: The incidental capture of cetaceans in fisheries threatens several species with extinction and represents a global conservation challenge. In order to assess the impacts bycatch on dolphins north-western Australian trawl fishery, I (i) examined reported skippers’ logbooks independent observer data; (ii) applied genetic methods estimate dolphin population structure connectivity; (iii) conducted an aerial survey abundance across simultaneously undertaking boat-based photo-identification infer fidelity fishery. From 2003-2009, between 180 366 were caught all management areas, depths seasons. Independent observers more than double logbooks. Significant predictors fishing vessel, time-of-day whether nets included Bycatch Reduction Devices (BRDs). Genetic evidence showed one panmictic trawler-associated common bottlenose (Tursiops truncatus), but isolation from adjacent, coastal populations Indo-Pacific (T. aduncus). Abundance was estimated at 2,000-3,000 T. truncatus 25,880 km2. While lack correction factors for availability bias mean this is likely underestimate, it lower previously thought. Trawler-associated individuals photographically genetically matched over periods days years. Recent logbook data suggest rates have increased since BRDs introduced. These results indicate that only considerable reduction trawling effort reduce bycatch; impacted does not recruit adjacent populations; number interacting trawlers fewer expected. chronic protected may affect population’s status. As consequence, classification acceptable limits requires revision light these first estimates Pilbara Trawl Fishery.