This bizarre floating gadget could save seabirds' lives
Many seabirds meet their end accidentally tangled in fishing nets. In a brand new approach to this problem, our Partners are studying the way seabirds detect predators, in a bid to use the same techniques to keep them away from netting.
Imagine you’re a Long-tailed Duck, and you see a fish in the water right underneath you. You dive towards it, looking forward to a tasty meal. But as you catch it in your beak, you hit a wall of near-invisible netting, meeting the same fate as the fish you’re trying to eat.
This is a danger that many seabirds face every day. Many modern ‘gillnets’ – vertical sheets of netting held up by floating buoys, which trap passing fish by the gills – are made of monofilament nylon that is practically invisible underwater. This material is widespread in fisheries around the world, and particularly popular among small-scale fishers owing to its low cost. Understandably, these nets pose a high risk of entanglement to many marine animals, including diving seabirds foraging nearby.
To the general public, ingesting plastic may be one of the most well-known threats to seabirds; yet an estimated 400,000 seabirds are killed each year through accidental ‘bycatch’ in fishing nets. The problem spans across the avian world: nearly 150 different seabird species thought to be susceptible to this danger.
To tackle this issue, researchers and conservationists including the RSPB (BirdLife in the UK) have for many years been exploring the potential to make gillnets more visible to birds underwater, through modifications to the nets, or adding devices such as high-contrast panels or LED lights. However, given the challenges of the underwater environment, where even marine birds have reduced vision, as well as the need to avoid warding off the fish themselves, underwater strategies have had – to date – limited success.
It was high time for a new approach. Researchers went back to the drawing board, asking simple questions: What do diving seabirds see? How do they forage? What do they avoid? With the help of animal behavioural ecologists and informed by tracking data, we realised the answer could lie in preventing birds from coming near the gillnets at all.
With this in mind, we looked into the scientific literature to find a response to our question: What could prevent birds from diving near gillnets in the first place? Thankfully, nature – as it often does – offered some hints. The conspicuous ‘eyespots’, which are found on many creatures such as butterflies, can evoke an avoidance response in many bird species. Similarly, looming movements have been found to trigger a collision-risk signal in birds’ brains, making them move away. On land, the combination of these two visual stimuli (i.e. eyes appearing to move towards a bird) has resulted in significant escape responses in several bird species.
To adapt this technique to the marine environment, we developed a floating buoy that displays large, obvious ‘looming-eyes’ that can be seen from a long way off. As the buoy bobs in the water, the tall pole sways conspicuously, and the eyes rotate in the wind. We called it the Looming-eyes buoy (LEB), or more affectionately, ‘The Bobby’.
Since February 2020, we have been working with our Partner the Estonian Ornithological Society to test the effect of this new device on birds out at sea. Trials are currently ongoing in Küdema Bay protected area, off the Estonian island of Saaremaa. The bay attracts large concentrations of wintering seabirds, including the Long-tailed Duck Clangula hyemalis and Steller's Eider Polysticta stelleri, both of which are Vulnerable to extinction, largely due to bycatch. Researchers are monitoring the behaviour of any seabird that enters within 50 metres of the ‘Bobbys’, compared to an area containing regular fishing buoys. No gillnets are present in either location, making the experiments completely safe for the birds. If these trials prove successful, the ‘Bobbys’ could be rolled out commercially, revolutionising bycatch prevention and saving seabird lives in gillnet fisheries across the world.