The researchers behind Patterns in abundance and size of sharks in northwestern Australia: cause for optimism for global shark conservation illustrate that when science, management, and enforcement work synergistically, sustainable resource use, recovery, and conservation outcomes can all be achieved.
Sharks and rays have conservative life histories (e.g. low fecundity, slow growth, high longevity). High fishing pressure and the consequent declines of many shark populations have generated global concern about their conservation status. In addition, substantial declines in apex predators, such as sharks, can alter entire food webs. Hence, information on shark population trends is essential for meeting sustainability objectives and furthering our understanding of ecosystem functioning.
Due to sustainability concerns for commercially-exploited shark species, it was decided to close an area of ca. 0.8 million km2 in northwestern Australia to commercial shark fishing. This happened in two stages, with one area closing in 1993 and a second area in 2005. The area has been closed to commercial shark fishing ever since but remains open to commercial fishing of scalefish and invertebrates (mostly prawns).
Between 2002 and 2107, the authors of the latest Editor's Choice monitored the abundance and size patterns of sharks in this area, using demersal longline surveys.
A total of 43 shark and ray species were sampled, with sandbar shark being the most commonly-caught, followed by milk, spot-tail, tiger, blacktip, dusky and sliteye sharks, and scalloped hammerhead. For these species, catch rates and mean sizes have been stable or increased in recent years.
Read the full paper in ICES Journal of Marine Science.
Tagging a sandbar shark as part of the shark abundance survey operations. Photo: Matias Braccini.