Dynamics of maturation, seasonality of reproduction and spawning grounds of the jumbo squid Dosidicus gigas (Cephalopoda:: Ommastrephidae) in Peruvian waters

In Peru, the giant squid Dosidicus gigas (D'Orbigny, 1835) is the most important cephalopod resource. The objective of the present paper is to analyse the reproductive cycle, and to determine the locations and potential of the spawning of D. gigas off the Peruvian coast between 1991 and 1995. The size of the first stage of maturity was estimated at 240-320 mm for females. Mature individuals were observed throughout the entire study period, although the main peak in spawning occurred between October and January with a secondary peak between July and August. An analysis of the seasonal cycle in spawning using maturity indices gave similar results and indicated the presence of two size groups with different maturity stages. Females were always more numerous than males during the study period and showed the highest incidence of mating in spring (September-November). Spawning took place along the entire coast of Peru with the greatest numbers spawning in the northern zone between 3 degreesS and 8 degreesS and the central zone between 12 degreesS and 17 degreesS. During 1993, there was an exceptional spawning ground in the southern zone during January and March. (C) 2001 Published by Elsevier Science B.V.