The use of artificial fish aggregating devices by the French tropical tuna purse seine fleet: Historical perspective and current practice in the Indian Ocean

Recent resolutions of the Indian Ocean Tuna Commission (IOTC) have been implemented to improve scientific knowledge on the effects of drifting fish aggregating devices (DFADs) through increased data collection and reporting. Here, we report information on DFADs collected from three distinct data sources to describe the use of DFADs and buoys by the French PS fleet of the Indian Ocean over the last decade. First, archives of buoy purchase orders during 2002-2014 were provided by fishing companies to give insight into the historical use of DFADs. Data show an homogeneity of the numbers of buoys available to each purse seiner and a steady increase of about 10 buoys per year per vessel, from 50-60 in the early 2000s to 200 in 2013. Second, information derived from satellite transmission data was made available for the period 2010-2013 based on quarterly reports that are produced by buoy supplier companies on a vessel basis. Data show an overall relative stability of the number of French buoys having been used to monitor floating objects (FOBs) during 2010-2013. Each French purse seiner operating in the IO has been monitoring a mean number of 90 FOBs (predominated by DFADs) on a quarterly basis during 2010- 2013, with some variability between vessels and seasons. The total number of FOBs monitored for the French component of the European PS fleet would be around 1,200 in the recent years. Third, an extended version of the PS logbooks has been implemented since January 2013 to include information on DFADs and associated buoys. Although incomplete for some vessels, data collection has been improving over time and several skippers now report a large amount of information on DFADs on an operation basis. This information appears complementary to the two other sources of aggregated data and allows identifying the areas of DFAD deployments for instance.

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