Looming Eyes Buoy
© Andre Kalamees
Sea Turtles
Shark decoys have been shown to work as sea turtle 'scarecrows', though these decoys also frightened-off target finfish species (tunas, billfish, mahi-mahi). However, there remains potential to develop decoys which maintain target species catch rates while deterring sea turtles from approaching baited longline hooks.
In tank trials, shark shapes triggered an innate flight response in captive-bred sea turtles that had not been exposed to sharks or other predators. In more recent at-sea trials, shark shapes reduced the number of turtles caught on nets.
Research is required to identify the shark characteristics most repulsive to sea turtles. It has been suggested that, for example, adding motion or sound may make the decoy appear more lifelike.
Exploiting the difference in visual systems between turtles and tunas (and other commercially important fish species such as billfish and mahi-mahi) may be a way to decrease turtle bycatch while maintaining target species catch. Turtles can see into the ultraviolet light (UV) spectrum while tunas etc can't. For example, by constructing decoys from transparent, UV-absorbent plastic, shark shapes may appear as black silhouettes and trigger avoidance behaviors in sea turtles while remaining transparent and undetected by target fish species.

The 'looming eyes buoy' (LEB) exploits visual stimuli that trigger an avoidance response or collision risk signal in birds' brains. It combines large ‘looming eyes’ (visible from a long way off) and conspicuous movement, with the eyes rotating in the wind as the tall pole sways and bobs in the water. While preliminary trials found that the LEB  had potential to reduce seabird bycatch, follow up controlled trials found no effect of LEBs on bycatch (nor target catch - lumpfish). An unexpected but positive outcome of the trials was a strong correlation between bycatch rates and fishing depths, suggesting that depth-based fishing restrictions could virtually eliminate the bycatch of seabirds in this fishery.

Recent trials with a visual deterrent dubbed the 'Scarybird' (a bird of prey shape 'flying' over the fishing area) found that it kept a large portion of birds away from the vessel during fishing operations. Target catch was unaffected. This device may be applicable to other gears, where interactions with birds occur mainly close to the surface.
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