The wedge clam (Donax trunculus) hand-operated fishery in the NW Mediterranean Sea: Landings, catch composition, damage rates and impact of fishing activity

Abstract

The bivalve wedge clam Donax trunculus is a highly valued species in Spain, but wild stocks have decreased in the Mediterranean region in recent decades. Internal demand exceeds the existing supply derived from local production. Hand-operated dredge fishery is still important in some coastal areas of Spain, such as the Ebro Delta (NE Spain). However, scientific information is lacking on most aspects of this fishery which is essential for its sustainable management. In this context, this study aimed to provide the first characterization of the hand-operated dredges fishery; evaluate the damage of this fishery on the megabenthic fauna; and analyze the impact of the fishing activity on the wedge clam. Our results indicate that landings declined dramatically since the mid-1990s and the main causes for this decline are postulated. Fishing effort was highly seasonal, being more intense from March to September. The discard fraction was very small (5.74% in abundance and the 3.74% in biomass) and 61.93% of the discards did not suffer damage. Clam fishing activity had an impact on recruit density in the short term (3 months), but not on recruit size and commercial fraction density, biomass and size. Our results provide tools for a better management of this type of fisheries.