Effects of food provisioning on site use in the short-tail stingray Bathytoshia brevicaudata

ABSTRACT: Food provisioning can have significant effects on marine wildlife. It is common practice for recreational anglers to discard fish waste back into waterways, yet the effects of incidental provisioning as a result of recreational fish cleaning on marine wildlife have not been assessed and are likely not being considered in fisheries management. At the Woollamia boat ramp in Jervis Bay, Australia, local anglers have been incidentally provisioning short-tail stingrays Bathytoshia brevicaudata through fish-cleaning activities for >30 yr. This provided an opportunity to investigate the influence of provisioning on a small scale. We used behavioural observations to assess stingray site use patterns against provisioning intensity to determine if provisioning can cause changes to the movements and behaviour of this large, marine mesopredator. Twelve female short-tail stingrays were found to use the site during observation periods for this study. Their presence was significantly correlated with the intensity of provisioning events (cumulative duration per observation session), which occurred most often in the afternoons. Significantly more stingrays visited during provisioning than pre-provisioning in simulated provisioning trials at sites where stingrays are not normally provisioned. Additionally, stingrays were considered to be exhibiting anticipatory behaviour as evidenced by increased visitation in the afternoon, irrespective of whether the fish-cleaning table was in use. These data indicate an influence of provisioning on the stingrays’ movements and use of the site and has implications with respect to accepted practices for discarding fish waste.