Todarodes filippovae in the Southern Ocean : an appraisal for exploitation and management

Todarodes filippovae Adam 1975 is a large oceanic ommastrephid squid with a pelagic distribution. It is closely related to T. angolensis but allozyme data have shown that the two species are separated by about the same genetic distance as other ommastrephid congenerics. T. jilippovae itself may comprise more than one species. It is reported to be widespread in the Southern Ocean from sub-Antarctic waters to north of the subtropical Front, but there are gaps in its known distribution which cast doubt on the conspecificity of the different populations. Squid identified as T. filippovae inhabit the open ocean up to the continental slope and they appear not to extend into shelf waters. Distribution of the various populations seems to be Jinked to the high velocity regions of the Antarctic Circumpolar Current, Falkland Current, Benguela Current and East Australia Current and these are probably important for transport of planktonic eggs and paralarvae and for the productive mesoscale features that these highly dynamic systems provide for adult feeding. Beaks attributed to T. filippovae have been found in the gut contents of sperm whales (Physeter catodon), southern elephant seals (Mirounga leonina), fish (Merluccius australis polylepis) and possibly by albatrosses (Diomedea melanophrys); however, there are insufficient data to estimate the annual consumption by known predator species. The juveniles feed on crustaceans, whereas the adults feed primarily on fishes and other cephalopods. In common with many other squid, they probably occupy a broad trophic niche. Knowledge of the life cycle is very incomplete. Spawning occurs in the Tasman Sea and off South Africa and probably takes place in the austral autumn and winter. The life span may be up to two years. Fishery potential has not been established, but in the Tasman Sea commercially viable catch rates have been reported. Effective exploitation and rational management of T. filippovae, or filippovae species/subspecies complex, requires research on species identification and stock structure, a full understanding of the life cycle of the different populations, knowledge of the relations between ocean currents, mesoscale oceanographic processes and biology, and a better understanding of role in the diet of higher predators