Frequency and temporal trends of shark predation attempts on bottlenose dolphins (Tursiops aduncus) in temperate Australian waters

摘要: Sharks are apex predators that influence the behavioural ecology of a range prey species. Unsuccessful predation attempts from sharks evidenced by fresh bites and scars, these wounds provide indirect measures pressure. To better understand predatory dynamics on bottlenose dolphins, we investigated frequency, sex age class differences, seasonality annual trends, location (open vs. sheltered waters) shark Tursiops aduncus off Bunbury, south-western Australia. Over seven years 2007 to 2013, standardised boat-based, photographic-identification dolphin surveys (n = 600) were conducted year-round over 540 km2 in open coastal waters (bay, estuary river). The overall frequency dolphins (calves, juveniles adults) was 16.9% (58 343). Shark categorised as Open 25, 40.9%), Intermediate 16, 26.2%) Scars 20, 32.8%). Scarring frequencies did not differ significantly between sexes or among classes. Bites increased 2009 coinciding with sustained warm water temperatures 2011 La Nina conditions, resulting 34% being recorded 2013. differed seasons, more prevalent during summer 2012/13. proportion greater for individuals residing (24.7%, 19 77) compared (13.4%, 34 253). Our findings knowledge into predator-prey marine top quantifying temporal spatial incidences failed temperate, south-west