Oral Presentation Australian Society for Fish Biology Conference 2017

Top shelf bottom feeders - Food provisioning in stingrays (#114)

Joni Pini-Fitzsimmons 1 , Culum Brown 1 , Nathan Knott 2
  1. Biological Sciences, Macquarie University, Marsfield, NSW, Australia
  2. Marine Ecosystems Unit, New South Wales Department of Primary Industries, Huskisson, NSW, Australia

Food provisioning can have significant effects on marine wildlife, and may cause behavioural changes, alter population structure and trophic balance, and cause significant health impacts on target species. It is common practice for recreational anglers to discard fish waste back into waterways, yet the effects of incidental provisioning as a result of processing marine recourses have not yet been assessed, and are likely not being considered in the management of recreational fishing along Australia’s coastline.

At the Woollamia boat ramp in Jervis Bay, local fishers have been incidentally provisioning short-tail stingrays through fish cleaning activities for >30 years. This provided an opportunity to investigate the influence of provisioning on a small scale. We used behavioural observations to assess site use patterns against provisioning intensity to determine if this level of provisioning has the potential to cause changes to the movements and behaviours of this large marine mesopredator.

Fifteen (adults, N = 7; sub adults, N = 8) female short-tail stingrays were found to use the provisioning site, including at least 5 gravid individuals. Their presence was significantly correlated to the intensity of provisioning events (P <0.001) and significantly more stingrays visited post-provisioning than pre-provisioning (P < 0.001) during simulated provisioning trails at other sites. These data indicate a strong influence of provisioning on the stingrays’ movements and use of the site. Based on the observed population structure, we also suggest the area may have reproductive significance for this species.

We provide a baseline of the effects of incidental provisioning as a result of processing marine recourses, on which monitoring and management programs can be built. This study has implications for recreational fisheries management and the management of marine provisioning globally.