The complete footprint of the Patagonian scallop bottom-trawl fishery on the Argentine shelf

ALBERTI, J.; FUNES, M.

Douglas

Workshop; 23rd International Pectinid Workshop; 2024

Human footprint on terrestrial and aquatic ecosystems began long ago, increasing faster during the last centuries. Particularly, concerns about the potential impacts of fishing have since magnified. For example, bottom-trawl fisheries gained attention due to their potential impacts on target and non-target benthic species and climate change (since sediment disturbance could release greenhouse gasses into the atmosphere). Thus, one key aspect to properly evaluate these impacts is to know the spatial extent of the fishing ground, along with the frequency of disturbances in previously fished areas. With the advent of new technologies (such as vessel monitoring systems), scientists could determine that the footprint of bottom-trawl fisheries on continental shelves around the globe, and in recent years, is highly variable. Long-term fine-grained trawling data could provide valuable background information to evaluate bottom-trawl fishing impacts. In this context, logbooks still play a central role in evaluating the whole impact of most fisheries on the seafloor. Here we provide a brief description of the Patagonian scallop fishery database populated with curated logbooks and publicly available information. We used its high-precision information for the entire set of tows from the fleet (since the beginning of the fishery) to estimate the shelf surface disturbed by trawling and the frequency of trawling disturbances.The Patagonian scallop’s database contains information on all fishing tows from a fishery that started in 1995 and is still ongoing. This database has more than a million fishing tows registered, with highly precise information for more than 80% of them. The aggregated swept area by all tows during these 29 years reached 48’769 km2, which represents a minor portion (~3%) of the Argentine continental shelf (approximately 1'530'000 km2). The swept area by those tows with precise information reaches 39’734 km2. Interestingly the shelf surface effectively disturbed was 14’137 km2 (almost a third) due to the overlap of tows within and between years (Fig. 1). Notably, the intra-annual overlap of tows is the highest frequency of trawling disturbance. Overall, during the entire history of the fishery, less than 1% of the Argentine continental shelf was affected, with 50% of interannual overlaps occurring on a time lag lesser or equal to 6 years.