Collection of Data for Fishery Biology Studies and Fish Stock Assessment

Basic objective of fisheries research is to provide ample information on the status of fish stocks. This information is collected through various sampling procedures and the data are used to provide advice on the sustainable management of fish stocks, upon which the entire fishing industry depends. There are two main sources of data collected and used in fisheries research. These can be divided into fishery independent and fishery dependent data. The first usually involves monitoring the changes in distribution over time in the relative or absolute abundance of fish populations using vessel based surveys in a way that is not subject to the biases inherent in commercial fishery data. The collection and accurate interpretation of both fishery dependent and fishery independent data are of fundamental importance to our understanding of the fished species. Both are needed to gain an understanding of the magnitude of localized changes in fish communities, landings and productivity of the resource. Fishery dependent information involves collection of catch and effort data (CPUE) as well as biological sampling from commercial fisheries. CPUE data are usually collected from logbooks or using direct observation at the site of landings. The underlying assumption is that changes in CPUE accurately reflect changes in the abundance of the fish stocks.