Dolphin depredation in Mediterranean and Black Sea fisheries: Methodology for data collection

When marine mammals come into physical contact with fishing gear, there can be harmful effects to both the animals and fishers. The animals may be incidentally caught in fishing gear, or in the case of depredation, marine mammals – usually dolphins – may remove and/or damage fish captured in nets or hooks, resulting in damage to fishing gear, loss of capture and consequently lower catch values and fisher revenues. Depredation can also lead to entanglement, which can in turn produce incidental catch. The competitive overlap between dolphins and humans at sea represents a worldwide issue, as it affects both the survival of wild dolphin populations and the livelihoods of fishers, and it is receiving growing attention from fisheries management organizations around the globe. Many gaps still remain, however, in the knowledge of the actual extent of the problem, including in the Mediterranean and the Black Sea. In order to understand and mitigate dolphin depredation in the region through effective management measures, adequate regional/subregional and national monitoring programmes are required to obtain representative data on dolphin depredation events during sampled fishing operations. The purpose of this protocol, which allows for replicability and comparisons among fisheries across the region, is to facilitate and improve data collection in a harmonized and standardized way. Its aim is to improve understanding of the dolphin populations involved in depredation events, assess the regional magnitude of depredation to determine the economic losses suffered by fishers, identify the typologies of fishing practices that lead to depredation, as well as potential mitigation measures, and collect information for the conservation of marine mammals.