Trends in an Indonesian coastal fishery based on catch and effort statistics and implications for the perception of the state of the stocks by fisheries officials

Indonesia's capture fisheries are monitored in each district of all 27 prov inces with a comprehensive catch and effort data recording system that was installed in 1976. The annual data are sent to the Indonesian Directorate G eneral of Fisheries (DGF) in Jakarta, where these are aggregated for nine r egions. Catches for the 45 recognised fish categories are accumulated in fo ur major fish groups and analysed with conventional fisheries surplus model s to estimate maximum sustainable yields (MSYs). These estimates have been used by DGF to determine the number of fishing licenses for each region in the nation's economic exclusive zone (EEZ). This paper discusses the effect of data aggregation and accumulation on the variance around trends in fish eries data of the South Sulawesi province. Simple regression techniques are applied to time series of catch, effort, catch-per-unit-effort, and number s of boats. At the lowest level of data aggregation and accumulation we fin d the highest variance. Although high variance obscures the perception on t he state of fish stocks at the lowest levels, perceptions at the highest le vels are not necessarily more useful for fisheries management. Bias caused by motorisation of the fleet by using CpUE as an indicator of fisheries mor tality and by combining data from administrative units that have no ecologi cal or biological meaning obscures the detection of trends. (C) 1999 Elsevi er Science B.V. All rights reserved.