Objective assessment of maturity in the Patagonian squid Loligo gahi (Cephalopoda: Loliginidae) from Falkland Islands waters

Abstract

An objective assessment of maturity in the loliginid squid Loligo gahi was tested using a method developed for L. pealelii utilizing principal component and discriminant analyses. Samples were taken from both seasons of the commercial fishery in the Falkland Islands (prosecuted south of 51°20'S) in 1994 and 1995. In addition, research samples were taken in January, June, and November, outside the fishing seasons, to provide individuals of a greater range of size and maturity. The method, using a combination of indices of somatic and gonad lengths and scoring abundance of eggs and spermatophores in females and males, respectively, proved to be successful both in a research context, when variables can be measured to a high degree of precision, and in a fisheries context where less precision is practicable. The method also detected anomalies in the maturity status of squid that might have been overlooked in a more subjective assessment, corroborating the accumulating evidence for batch-spawning in loliginid squid. Four stages of maturity were recognized for female squid and three for male squid.