Conventional tagging of sharks in Western Australia: the main commercial species exhibit contrasting movement patterns

Abstract

Understanding movement patterns underlies effective management and conservation measures. The current study summarises the main findings from a tagging program of Western Australian sharks to provide insights into the movement patterns of the main commercial shark species: dusky (Carcharhinus obscurus), sandbar (C. plumbeus), gummy (Mustelus antarcticus) and whiskery (Furgaleus macki) sharks. Between 1993 and 2020, >12 000 individuals from 52 taxonomic groups were implanted with conventional tags in Western Australia, of which 8.5% were recaptured. Most of the tagged (74.5%) and recaptured (95.8%) individuals belong to the four main commercial shark species. Recaptured individuals of these species, as well as tiger (Galeocerdo cuvier) and bronze whaler (C. brachyurus) sharks showed displacements of >1000 km and rates of movement (ROMs) of >10 km day–1, with the exception of whiskery sharks, which showed much slower ROMs (<3 km day–1). Despite tagged dusky and sandbar sharks being predominately small individuals and gummy and whiskery sharks being large individuals, dusky and sandbar sharks had faster ROMs and a greater proportion of recaptures outside the release zone. Our study provided the information required for estimating movement rates across different fishing zones and therefore defining the spatial scale for managing these shark species.