Critical transitions in early life histories of short-finned squid, Illex illecebrosus as reconstructed from gladius growth

Early life growth of the short-finned squid, Illex illecebrosus (Mollusca: Cephalopoda), was reconstructed from periodic increments deposited on the gladius structure of squid collected in the Gulf Stream/Slope Water front and the Scotian Shelf. The general effects of environmental changes and lifestyle transitions in the variation of size-specific gladius growth was investigated. Tho offshore growth was exponential and at least six size-specific growth phases were distinguished. Paralarval growth ended at approximately 10 mm gladius length (GL). An important change in growth at 30-40 mm GL was associated with the shift from the macroplanktonic to micronektonic habitats and the transition from the Gulf Stream to Slope Water. The approximation to the Scotian Shelf/Slope Water Front was suggested as related to a growth transition at 68 mm GL. A change to linear growth occurred after the nektonic lifestyle was attained on shelf waters (90 mm GL).