Standardization of a geo-referenced fishing dataset for the IndianOcean Bigeye Tuna, Thunnus obesus (1952–2014)

Abstract. Geo-referenced catch and fishing ­effort data of the bigeye tuna fisheries in the Indian Ocean over 1952–2014 were analysed and standardized to facilitate population dynamics modelling studies. During this sixty-two years historical period of exploitation, many changes occurred both in the fishing techniques and the monitoring of activity. This study includes a series of processing steps used for standardization of spatial resolution, conversion and standardization of catch and effort units, raising of geo-referenced catch into nominal catch level, screening and correction of outliers, and detection of major catchability changes over long time series of fishing data, i.e., the Japanese longline fleet operating in the tropical Indian Ocean. A total of thirty fisheries were finally determined from longline, purse seine and other-gears data sets, from which 10 longline and four purse seine fisheries represented 96 % of the whole historical catch. The geo-referenced records of catch, fishing effort and associated length frequency samples of all fisheries are available at doi.pangaea.de/10.1594/PANGAEA.864154.