A review of the biology of the jumbo squid Dosidicus gigas (Cephalopoda:: Ommastrephidae)

The taxonomy, functional morphology, evolutionary biology and ecology of the jumbo squid, Dosidicus gigas, were reviewed using the data from many Soviet/Russian expeditions and all available literature, D. gigas is one of the largest and most abundant of the nektonic squid in the epipelagic zone of the world Ocean. It occurs in the eastern Pacific with its species range limited by the isoline of phosphate concentration of 0.8 mg-at P-PO43-/m(2) in the 0-100 in layer. Three intraspecific groups of D. gigas may be distinguished on the basis of the size of adult males and females: small (mantle length (NIL) of adult males 130-260 nun, females 140-340 mm), medium-sized (240-420 and 280-600 mm, respectively) and large (> 400-500 mm and 550-650 to 1000 mm. and more, respectively). Growth is rapid. The life span of all three groups is about 1 year, with the biggest specimens of the large group probably living 2 years. D. gigas are monocyclic with the highest potential female fecundity among cephalopods; up to 32 million oocytes. Spawning takes place throughout the year, with a distinct peak during spring and summer in the southern hemisphere (October-January). D. gigas is an active predator. The most common prey among fish species are epipelagic lanternfish, and among squid species are ommastrephids, including D. giga's. Throughout the whole life cycle the prey sizes constitute 5-15% of the squid total length. Parasite fauna include 9-12 species of nematode, cestode and trematode, and the ciliate Chromidina. The total instantaneous stock of D. gigas within the limits of the species range was estimated at around 7-10 million tonnes, including around 2-4 million tonnes in the open ocean beyond the exclusive economic zones. (C) 2001 Published by Elsevier Science B.V.