Gillnets trap and kill at least 400,000 seabirds attracted to fish smells each year. A recent study suggests that pairs of googly eyes – essentially, floating scarecrows – could significantly reduce these bycatch.
The problem of bycatch
Gillnets are “sheets” of netting suspended in water. Although particular species of fish may be targeted by area, the use of this technique carries the risk of bycatch (incidental capture of non-target species) and of interaction with other marine animals.
This is particularly the case with birds, such as Albatrosses and other northern gannets. Attracted by the odors of fish from several kilometers away, these animals do not hesitate to dive into the water to grab a “free meal”. Unfortunately, many then get tangled in the ropes and eventually drown.
As part of a study published in 2013, researchers had identified 148 species of seabirds sensitive to these bycatch, mostly in temperate and subpolar regions of both hemispheres. A review of reported catch estimates suggested, at the time, that at least 400,000 birds per year died in these nets.
In 2018, members of the BirdLife International association began to think about ways to prevent these events.
“We believed that if we could prevent vulnerable seabirds from diving too close to gillnets in the first place, we could finally tackle bycatch in a meaningful way.”, underlines Yann Rouxel, project manager at BirdLife International. It was then that Mr. Rouxel and his team had the idea of a scarecrow sailor.
From then on, the team teamed up with several scientists from the Estonian Ornithological Society and engineers from Fishtek Marine, a company that makes fishing equipment, to develop a new type of wide-eyed buoy. Much like the scarecrows that line the fields, these devices would aim to deter birds by intimidating by mimicking the eyes of a large predator.
A prototype was recently tested (250 hours of observation) with a population of long-tailed diving ducks in Küdema Bay, Estonia. The results of this study, published in the journal Royal Society Open Science, suggest that the presence of these big-eyed buoys may reduce the number of these birds by 20 to 30% within a radius of fifty meters compared to traditional buoys.
Additionally, the authors also found that the ducks were quick to return to areas they had left once the scarecrows were removed. These behaviors suggest that these buoys do have an influence, but that it is not permanent.
A device to be perfected
While this prototype has shown promise, more work will be needed to expand the concept. This buoy is currently too heavy to be deployed in gillnet fisheries. That’s why the researchers plan to develop a smaller, lighter version. Tests will soon be carried out in Icelandic waters.
If successful, these devices could one day be used on a large scale in an attempt to reduce seabird bycatch. However, this approach alone will not solve the problem. On the one hand, because its effectiveness is limited, but also because the scale of incidental catches of seabirds is probably under-reported.