Chum dine with me: assessing the effects of wildlife tourism on non-target fish assemblages

Context: Wildlife tourism is becoming increasingly popular and often uses bait and berley to attract the target species and enhance customer experience. However, few studies have assessed the effects of food-based attractants on non-target species. Understanding the impacts of provisioning on the marine ecosystem, including non-target species, is required to assess the effects of wildlife tourism comprehensively. 

Aims: We compared fish assemblages at a white shark cage-diving site to those at other offshore islands to assess whether any detectable differences could be observed and attributed to shark diving operations. 

Methods: We used baited remote underwater video stations (BRUVS) to quantify and compare fish assemblages across a 6-year timespan at the Neptunes Islands Group (South Australia) and six reference locations. The Neptunes Islands Group consist of one high provisioning site, where most (~85%) of the bait and berley input takes place, and one lower provisioning site, where operators visit less frequently. 

Key results: Fish assemblages at the Neptunes Islands Group and all other offshore islands had similar levels of variability. There was a higher total abundance of fish at both Neptune Islands sites than at reference sites, driven by higher abundances of horseshoe leatherjacket, Meuschenia hippocrepis, and barber perch, Caesioperca rasor. However, there were no detectable differences in species richness or evenness between the Neptunes Islands Group and other offshore islands. 

Conclusions: Despite operators using food-based attractant on a near daily basis and some fishes feeding on bait and berley continuously, the cage-diving industry has minimal effects on demersal fish abundance and diversity. 

Implications: This suggests that the current level of provisioning has limited ecological impacts on the reef fish community and highlights that the management regulations are currently suitable for non-target fish assemblages.