Artisanal dredges as efficient and rationale harvesting gears in a Patagonian mussel fishery

Dredges authorized to operate in shellfisheries of San Matías Gulf changed after 2000 from industrial (≈300 kg, 2.5 m wide) to smaller ones (≈50 kg, 1.6 m wide) exclusively operated by artisanal boats (<9.9 m long). The main objective of this study was to assess the efficiency and species selectivity of the artisanal dredge, and compare catches composition between dredge and commercial divingon a mussel fishing ground located in coastal waters. The experimental design included samplings from dredge catches, dredge tracks, control sites and commercial diving. Dredge efficiency averaged 89% and mussels represented 78% in dredge and 97% in commercial diving catches. Bycatch totalized 46 and 27 species, respectively, and was dominated by sea urchins and ophiuroids. The artisanal dredge resulted to be highly efficient compared to the industrial dredges previously used and those used worldwide. Changes of the fleet scale and gear design seem to have led to a significant reduction of the fishing effort and impact in San Matías Gulf mussel fishery.

► We used a methodology based on direct methods for estimates of selectivity (diving behind the dredge track).
► We identified a higher efficiency of the new dredge comparing with that of dredges used for shellfish worldwide and before 2000.
► The artisanal dredge was less species selective comparing with commercial divers.
► Also, effects of dredging appeared to be focused in the removal of substrates.
► Changes of the gear design seem to have led to a significant reduction of the fishing effort and impact in San Matías Gulf mussel fishery.