"When the seagulls follow the trawler, it's because they think sardines will be thrown into the sea." - Eric Cantona
Football legend Eric Cantona knew a thing or two about the feeding habits of seabirds that follow fishing trawlers in the hope of picking up a free lunch. But surprisingly, very little is known about the relationship between fishing boats and scavenging seabirds, nor what might happen to them if plans to ban this practice come into operation next year.
The research by Stephen Votier in the Marine Biology & Ecology Research Centre, University of Plymouth and Stuart Bearhop, University of Exeter, published this month in the Journal of Applied Ecology, found that gannets tend to either follow the trawlers and gorge on whitefish (such as haddock), which they would normally never have access to, or ignore the trawlers to forage for their more traditional diet of mackerel, sprat and garfish. The birds that ate mostly white fish tended to be in poorer condition than those that pursued a more natural diet.
"It's been suggested that discards are like junk food for sea birds," says Stephen Votier. "White fish has more protein, but lacks some essential fats and omega oils present in oily fish like mackerel. We don't know whether the change in diet has caused the deterioration in their condition, or whether it's just that weaker birds tend to go for the easy option."
The population of gannets has risen exponentially over the past few decades, and it has been suggested that this has been assisted by the availability of discarded bycatch. Next year new rules are set to come into force in the EU which may ban the practice of dumping the unwanted catch into the sea.
The Universities of Plymouth, Exeter and Leeds have now received a £700,000 grant from the Natural Environment Research Council (NERC) for a collaborative project to investigate the causes and consequences of individual specialisations in gannets.
