What is known about effects of provisoning on sharks and ray and how future research should investigate different scales?

We recently published a paper that review the research that has been conducted so far on the effect of shark and ray provisioning on the animal’s ecology, behaviour and health.

Shark and ray provisioning is a rapidely growing indstry that offers tourist with an increased probability of interaction with elusive animals buy attracting them with food or even feeding them to habituate them to visit the diving site. This activity is widespread around the world and involve different species.

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We reviewed the 22 available studies on this topic involving 14 shark and 3 ray species targeted by artificial provisioning to investigate their behavioral, physiological, and ecological response.

We first report similar individual response by sharks and rays, including change in horizontal movements or emergence of an anticipatory response. However, all studies demonstrate that the propensity to respond to provisioning operations varies both among elasmobranch species and among individuals within each species. The effect on diet and foraging behaviour is yet to be better investigated as this topic has been understudied so far; the 2 availaible studies showing contrasting patterns that might be due by different provisioning practices.

We also investigated the potential effects at the group scale. We report a number of studies showing an aggregation effect with an increased abundance of the targeted species at the feeding site. Provisioning operations can influence group composition in terms of species and genders that are aggregated. It can aggregate naturally gregarious species but also solitary species creating an artificial interacting zone. However, most studies indicate that there is unlikely an effect on the natural cycle of the species involved, as for example, most species appear to keep conducting their breeding migrations despite the possibility to stay at the provisioning site. On the other hand, aggregation at a specific site can promote intra-specific aggression or competition.

We also reported the community-scale effects, including the effects of distribution of predators and prey or chnaging elasmobranch communities at the feeding site.

Although the effect on elasmobranch health has been yet underinvestigated, we discuss the potential effects that may impact animal’s health and body condition.

While a growing number of ecologists is investigating the potential effects of provisioning on sharks and rays, we took the opportunity to suggest a framework that take into account multi-scales when studying this topic. Until now, most of the studies have only been context dependent and focused on only one or two effects (e.g., effects on abundance or on movement patterns), but we highlight teh fact that scientists should now intergrate multiple effects and their interactions within their study. Indeed, most individual, group and community effects are not isolated and actively interact. A broader framework could therefore study the cascading affects accross the scales.

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Such a framework could benefit our understanding of the real effects and their strenght and importance on shark and rays health and behaviour.

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While the review was based on the potential effects of provisioning on sharks and rays, we also show that it is context dependent and not necessarily negative. This activity can have positive effect for conservation and awareness, or even null effects on some aspects. The strenght of negative effects is often related to the practices of the industry. If some operations are already conscious on the benefit of good practices to secure the durability of their activity and the health of populations of the species they target (http://globalsharkdiving.org/ , http://sustainablesharkdiving.com/), others only think about short-term financial benefit of the practice and do not adapt their practices to good code of conduct which is likely to negatively impact the industry.

Note also that the reported negative effects are nothing compared to other threats that sharks are facing every day (e.g. overfishing, habitat degradation, climate change…).

We hope our review will provide a good summary of the different effects that have already been studied in sharks and rays but also that it will encourage future researcher to use a broader framework to investigate the response of these marine animals to provisioning.

Our study is available here:

Brena PF, Mourier J, Planes S, Clua E (2015) Shark and ray provisioning : functional insights into behavioral, ecological and physiological responses across multiple scales. Marine Ecology Progress Series 538: 273-283.PDF icon

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