On the Nature of the Selective Fishing Action of Longline Gear

Abstract

Fishery biologists have, thanks to the magnitude of sampling provided by commercial fisheries, a better quantitative understanding of the populations with which they are concerned than do biologists interested in the quantitative aspects of other marine organisms. However, fishery biologists must be aware of bias that may be introduced by the sampling mechanism, the fishing apparatus. Fishing gear may be more effective in the capture of fish of some sizes or in some areas or seasons. If the nature of the bias is known allowance can be made for it, and its character may supply additional information on the population of fish.