A rational survey method for evaluation of trawl fishing ground

Abstract

The paper presents a method by which the optimum number of hauls for an area can be estimated when the desired precision for estimating fish abundance is given. This method is applied to an area along the east coast Gulf of Thailand. The area was divided into three subareas according to the various features of fishing conditions. Subarea-I contains 13 blocks and is located in the southernmost part of the area; subarea-II comprises 17 blocks in the northernmost part and extends eastwards in the form of a rectangle. The remaining 31 blocks are contained in the subarea-III which occupy the intermediate and off-shore regions of the two subareas. The superiority of trawl fishing ground is in the order of the subareas II, I and III. If an error of 20% can be tolerated for the estimate of fish abundance, sixty hauls are necessary for subareas I and III, while thirty hauls are sufficient for subarea-II.