Methods of Measuring Stock other than by the Use of Commercial Catch and Effort Data: FAO Fisheries Technical Paper No. 176

This paper reviews methods of monitoring the abundance of fish stocks other than by the analysis of catch and effort data. The main methods considered are: fishing surveys; acoustics, sightings and aerial surveys; egg and larval surveys; and tagging experiments. For each method consideration is given to the precision obtained, the possible causes of bias, and the costs involved. A tabulation is given of the advantages and disadvantages of different methods in respect of different types of stock. The ultimate choice of method depends on the biological and environmental characteristics of the situation, as well as the specific purpose of the work, and the resources of personnel, expertise and equipment that are available.