Chemical Deterrents


Turtles, elasmobranchs (sharks, skates and rays), and potentially seabirds detect chemical signals in the environment using their peripheral sensory systems. Exploiting this, chemicals have been suggested as a bycatch mitigation technique for various sensitive species – for example, by treating baits with certain chemical compounds that deter wildlife. 


The effectiveness of chemical deterrents as a mitigation technique depends on the sensory biology of the wildlife bycatch species. Some elasmobranchs have displayed an aversion to chemicals derived from a potential predator and toxins such as those produced by the Moses sole, Pardachirus marmoratus, but few chemicals have proven effective across all species of elasmobranch. Fish oils as a chemical deterrent for seabirds have been studied in demersal longline fisheries in the Hauraki Gulf, New Zealand, with varying success. Effective chemical deterrents for cetaceans have not yet been identified, with a study in the Mediterranean finding that dolphins interacting with nets were undeterred when a capsaicin-based (spicy) coating was applied to the nets.

The speed at which chemicals disperse (i.e. too slowly) may reduce the effectiveness of this technique, and there are concerns over the risk of polluting marine environments. No chemical deterrents have yet proven to be widely effective or practical to implement, and the technique has not yet been adopted by the industry.

Interested in how this and other measures could mitigate bycatch in your fishery? Get in touch with us to collaborate or take part in a study.

This page was last updated on 14.06.23.

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