This February, the Hellenic Ornithological Society’s marine team returned to the Gulf of Kalloni to work once again with local fishing boats and study the interaction between fisheries and seabirds, just like last year.
The Gulf of Kalloni in Lesvos is one of the most important feeding grounds for the Yelkouan Shearwater in the entire Aegean, especially at the beginning of the breeding season. Every year, from February to April, thousands of Yelkouan Shearwaters travel from the Black Sea to feed on the area's rich fish stocks. In 2024, up to 30.000 individuals were recorded entering the Gulf, forming large aggregations to feed on anchovies, locally known as ‘Hapsi’.
However, this search for food also comes with risks: while chasing anchovies, Yelkouan Shearwaters often get bycaught in fishing nets, leading to drowning. The accidental capture of seabirds in fishing gear (bycatch) is one of the most significant threats to these species. Therefore, in order to identify high-risk areas for bycatch within the Gulf, GPS transmitters were once again deployed this year on seven birds, which were captured at sea in the narrowest part of the Gulf.
Tracking their movements revealed by the transmitters allows us to better understand the species' daily and seasonal movements, key areas of importance, and the threats it faces. Early data already indicate that Yelkouan Shearwaters of the Gulf of Kalloni extensively utilize the wider Aegean region in search of food before returning to their colonies for breeding. Additionally, the transmitters confirm once again this year that the shearwaters alternate between shorter movements within the Gulf of Kalloni and longer journeys to the Black Sea.
And here comes the most exciting discovery: by capturing the birds at sea instead of in their colonies, we have the opportunity to uncover new breeding colonies! Each new colony is a significant step towards the conservation of the species, as it allows us to identify nesting areas that may need to be included in the network of protected sites and propose targeted conservation and management measures.
At the same time, our collaboration with fishermen continues. Together, we are testing solutions to reduce seabird bycatch, benefiting both birds and fishermen. The fishermen’s knowledge is invaluable to the success of this effort.
The Gulf of Kalloni constantly reminds us of its importance as one of Greece’s most productive marine ecosystems. Yelkouan Shearwaters and many other seabirds depend on it—and through research and collaboration, we can ensure that they continue to visit the Gulf year after year.
Stay tuned—the next journeys of the shearwaters will reveal even more secrets!
These actions were carried out as part of the LIFE PanPuffinus & LIFE MareNatura Projects, co-funded by the European Union, the A.G. Leventis Foundation, and the Green Fund.
101113792-LIFE22-NAT-EL-MareNatura