Sharks senses and shark repellents

Abstract

Despite over 70 years of research on shark repellents, few practical and reliable solutions to prevent shark attacks on humans or reduce shark bycatch and depredation in commercial fisheries have been developed. In large part, this deficiency stems from a lack of fundamental knowledge of the sensory cues that drive predatory behavior in sharks. However, the widespread use of shark repellents is also hampered by the physical constraints and technical or logistical difficulties of deploying substances or devices in an open-water marine environment to prevent an unpredictable interaction with a complex animal. Here, we summarize the key attributes of the various sensory systems of sharks and highlight residual knowledge gaps that are relevant to the development of effective shark repellents. We also review the most recent advances in shark repellent technology within the broader historical context of research on shark repellents and shark sensory systems. We conclude with suggestions for future research that may enhance the efficacy of shark repellent devices, in particular, the continued need for basic research on shark sensory biology and the use of a multi-sensory approach when developing or deploying shark repellent technology.

Effectiveness of five personal shark-bite deterrents for surfers

“…While these measures aim to reduce the probability of sharks and humans encountering each other, other measures aim to repel sharks directly from approaching people in the water. These deterrents have been developed to elicit a response by impacting one or more of the shark’s senses, including vision, smell, and electro-reception (see Hart & Collin, 2015). For example, various aposematic colour configurations (i.e., use of colours as anti-predator tactics) have been alleged to repel sharks.…”

Bubble Curtains: Herbivore Exclusion Devices for Ecology and Restoration of Marine Ecosystems?

“…Studies of bubble curtains as shark deterrents found that after initial success, sharks eventually breached the curtain that was protecting a bag of burley (Hart and Collin, 2015). Sporadic pulses of large bubbles in conjunction with the continuous curtain of small bubbles are considered to be more effective at protecting the bait (Hart and Kempster personal communication).…”

“…Bubble curtains have also been applied for fish herding in fishing and aquaculture, as a means of guiding fish in set-net fishing operations and retaining fish in enclosures (Stewart, 1982;Arimoto et al, 1993). Perhaps the most common application of bubble curtains, however, has been as a barrier to guide and deter the movement of aquatic species (Sager et al, 1987;Dawson et al, 2006;Zielinski et al, 2014;Hart and Collin, 2015). As deterrents, bubbles have been trialed and applied to prevent fish entering hydroelectric power stations (Linnansaari et al, 2015), restrict the movement of invasive species (Dawson et al, 2006;Zielinski et al, 2014) and as shark deterrents (Hart and Collin, 2015).…”

“…Perhaps the most common application of bubble curtains, however, has been as a barrier to guide and deter the movement of aquatic species (Sager et al, 1987;Dawson et al, 2006;Zielinski et al, 2014;Hart and Collin, 2015). As deterrents, bubbles have been trialed and applied to prevent fish entering hydroelectric power stations (Linnansaari et al, 2015), restrict the movement of invasive species (Dawson et al, 2006;Zielinski et al, 2014) and as shark deterrents (Hart and Collin, 2015). However, despite the success of bubbles in restricting fish movements in other systems, currently their potential application has never been tested on reef fishes, or as a method to prevent herbivores from feeding on marine vegetation.…”

“…Another significant advantage of bubble curtains over rigid cages is the low profile and drag of the physical structure reducing its risk of being dislodged by waves and currents. Air hoses used to generate bubble curtains are flexible and can therefore fit to the contour of a reef and theoretically be deployed in more exposed areas, where the drag forces on a rigid cage can • Nature: prey herding by marine mammals (Sharpe and Dill, 1997;Neumann and Orams, 2003;Wiley et al, 2011) • Aquaculture: fish herding in aquaculture (Arimoto et al, 1993) • Fish deterrence in hydro-electric power stations (Patrick et al, 1985;Sager et al, 1987) • Prevent the spread of invasive fishes in freshwater systems (Dawson et al, 2006;Zielinski et al, 2014) • Shark protection (Hart and Collin, 2015) • Reduce noise pollution (Würsig et al, 2000;Lucke et al, 2011) become a limiting factor (but see Sumi and Scheibling, 2005). Finally, by eliminating the need for a rigid three-dimensional structure, bubble curtains also reduce the physical hazard to users of the marine environment where they are deployed.…”