Tuna farms - a seasonal supplementary food source for storm petrels Hydrobates pelagicus melitensis

Abstract

The area investigated is located about 9 km east from the nearest shoreline at Marsascala (Malta), ca. 30 km from the main breeding colony of Filfla, situated 5 km off the south coast of Malta. The use of raw, unwashed fish food is fundamental in attracting storm petrels closer to these tuna pens. The same food supply has attracted a constant presence of small fish around the pens which in-turn attract gulls and terns, especially the black tern. Observations have shown that the majority of storm petrels frequenting the area are adult birds undergoing primary wing moult, suggesting breeders, probably not venturing far away from the colonies during the chick rearing period. While adult storm petrels regularly fall prey to yellow-legged gulls on Filfla, no interactions between gulls and storm petrels were ever noted near the tuna pens.