Abstract:

One of the endeavours to address the shortage of catch per unit effort (CPUE) information from the Indonesian Indian Ocean tuna fishery is the collation of a large amount of catch and effort data collected by Indonesian Fisheries High School students (“FHS data”). This paper attempts to investigate spatial-temporal patterns of catch and effort of the FHS data for the main tuna species caught by the fishery: bigeye tuna (Thunnus obesus - BET), yellowfin tuna (T. albacares - YFT), albacore (T. alalunga - ALB) and southern bluefin tuna (T.maccoyii - SBT). Reported sets occurred in the Eastern Indian Ocean, north and south of 20°S. Recorded effort from the FHS data set was concentrated within the only known SBT spawning ground. However, within this data set, SBT were recorded in the lowest catch proportion relative to BET, YFT and ALB. The catch composition data suggested that YFT and ALB were predominantly targeted by the fishery, with ALB and SBT most predominantly recorded south of 20°S, whereas BET and YFT were mostly recorded north of 20°S. Unfortunately, there was no strong information on targeting practices reported by this data set, limiting any attempts to understand the factors that influenced those results. As the sampling predominantly occurred in between July and December, the data are not representative of fishing activities throughout the entire year, and any seasonal patterns from the FHS data set are biased. In addition, the FHS data set is prone to observation error and uncertainty in terms of fish identification and fishing location. Therefore, the FHS data set needs to be interpreted with caution.

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