The Use of Netting Over Fishponds as a Hazard to Waterbirds

The problem of waterfowl becoming entangled and killed in netting suspended over fishponds, and the effectiveness of this technique in excluding birds from fishponds, was studied at two fish farms in Israel. A variety of physical and environmental factors of 101 netted fishponds with 20 net types were recorded, as were the number and species of dead birds entangled in the netting, and those observed alive under the netting. Numbers of dead birds were mainly a function of the net’s visibility: with fewer dead birds in small mesh size, and also in thick or dark-colored netting. Large numbers of dead birds occurred in netting made of thin monofilament even though it had small mesh size. The number of live birds at netted ponds was mainly a function of poor net maintenance, rather than net type. The results were used to formulate guidelines for using netting over fishponds in Israel, that include: fishpond netting should be made of thick, dark-colored material with small mesh size (<5 cm), and a total ban should be imposed on the use of thin monofilament nets. These guidelines will allow for better bird conservation, while reducing conflict between fish-farm managers and piscivorous birds.