Repaired shell damage in the commercial scallop Zygochlamys patagonica (King & Broderip, 1832), Argentine Sea

We present an overview of repaired shell damage in the scallop Zygochlamys patagonica in the commercial beds of the Argentine Sea. Presence of scars was registered in 11 962 scallops, ranging from 20 to 90 mm total height, from the fishing grounds in 2003 and also in 1995 (pre-fishery condition). Values of percentage of scarring (presence) were variable in all areas. Samples collected in 1995 showed the highest percentage of scars. As the highest records of scarring were registered in pre-fishery conditions, it is not possible to regard these marks as absolute indicators of anthropogenic disturbance caused by trawling activities. Moderate and severe damage was mostly recorded in individuals of commercial size (≥ 55 mm). This indicates not only the fragility of smaller scallops, but also the accumulation of damage in older specimens, probably more resistant to damage because of their thicker shells. The selective removal of commercial individuals could explain in part our results that indicate a higher percentage of repaired shell damage in 1995, when the average size of the population was also higher. Future investigations are needed to assess effects of scarring at different shell sizes (ages) and relate these to levels of survival in Patagonian scallops thrown back into the sea during processing on board.