Seawater temperature, a-chlorophyll and zooplankton samples support a new paradigm: Coastal waters off northern Patagonia play a major role as spawning and nursery areas for early life-cycle planktonic stages of the Argentine squid Illex argentinus

CRESPI ABRIL, CÉSAR A.; BARÓN, PEDRO J.; MORSAN, ENRIQUE M.

Pucón

Simposio; 5th International Zooplankton Production Symposium; 2011

International Council for the Exploration of the Sea / North Pacific Marine Science Organization

Illex argentinus sustained the world’s largest cephalopod fisheries during the last decade. Based on the spatial distribution of mature individuals and paralarvae on the confluence of Brazil-Malvinas currents and the mid/outersustained the world’s largest cephalopod fisheries during the last decade. Based on the spatial distribution of mature individuals and paralarvae on the confluence of Brazil-Malvinas currents and the mid/outer shelf off northern Patagonia, researchers have interpreted that major spawning stocks having distinct life-cycle chronologies segregate during discrete time periods in specific areas of the mid/outer shelf and shelf break off Argentina to Southern Brazil, and that either: 1) neutrally-buoyant egg-masses drift to the confluence of Brazil- Malvinas currents (B/M-C) where hatching might take place, or 2) mature females migrate long distances to the B/M-C to spawn. However, alternative life-cycle hypotheses involving the use of coastal areas as spawning and nursery grounds have not been explored. In this study we evaluate the suitability of different areas of the species’ range for early life-cycle development by spatially modeling a combined function of the monthly probability of: 1) embryonic survival, based on experimental data and SST remote sensed information (NOAA-AVHRR), and 2) paralarvae survival, based on primary productivity availability estimates (chlorophyll a concentration, SeaWiFS). Also, we sampled coastal waters off northern Patagonia searching for paralarvae of I. argentinus. Our model shows that coastal areas may play a major role as spawning and nursery grounds of the species that has beena concentration, SeaWiFS). Also, we sampled coastal waters off northern Patagonia searching for paralarvae of I. argentinus. Our model shows that coastal areas may play a major role as spawning and nursery grounds of the species that has beenI. argentinus. Our model shows that coastal areas may play a major role as spawning and nursery grounds of the species that has been previously neglected. Also, we confirmed our predictions by reporting the finding of paralarvae of I. argentinusI. argentinus in zooplankton tows conducted in coastal waters off Patagonia and of juveniles (25-39 mm ML) found stranded on the coast at 42.8ºS.