1. Dolphins are often blamed for reducing fisheries
catches and may be killed in retaliation. Depredation of fishing gear in
coastal Mediterranean waters is normally caused by bottlenose dolphins.
Economic impact, however, may be modest even within areas of reportedly
acute conflict.
2. Boat surveys and interviews were conducted to investigate dolphin occurrence and interactions with fisheries within the 167 km2 Porto Cesareo Marine Protected Area (MPA) in southern Italy. Based on
69 interviews with fishermen using bottom-set trammel and gill nets,
there was reportedly a high occurrence of depredation by bottlenose
dolphins. Depredation was reported by 92% of the fishermen operating in
or near the MPA, and 67% of them claimed an economic cost in excess of
€1000 per year, with a mean reported cost of €2561: a higher impact than
in other Mediterranean studies.
3. According
to local fishermen, dolphin occurrence and depredation peaked in spring
and autumn, coincident with the study's surveys at sea. Dedicated
visual surveys totalling 1255 km of effort, however, resulted in no
encounters with cetaceans. Information from interviews and boat surveys
was therefore contradictory, suggesting that reports of acute
depredation do not imply a constant presence of dolphins within the MPA.
4. While
depredation in the MPA might be caused by wide-ranging dolphins or
incursions occurring overnight, damage may well be overestimated or
over-reported. As local fishermen had previously benefited from
subsidies, interviews made during this study could be perceived by some
as an opportunity to influence future decision-making regarding monetary
compensation for the impact of depredation.
5. Evidence from interviews also indicated that species and factors other than dolphins were responsible for part of the damage.