Effect of retention processes on the recruitment of tropical arrow squid (Doryteuthis pleii): An individual-based modeling case study in southeastern Brazil

Abstract

Squid recruitment depends on paralarvae survival, as the parental stock dies following reproduction. Therefore, the biotic and abiotic environmental conditions experienced by paralarvae control recruitment strength. To benefit from the favorable environments (i.e. nursery grounds) in the dynamic pelagic domain, paralarvae rely on passive retention by currents to remain in suitable nursery habitat. To evaluate the retention conditions for tropical arrow squid (Doryteuthis pleii) paralarvae off the South Brazil Bight (SBB, 22–29 °S), we ran a series of particle-tracking Individual-Based Models (IBM) coupled to a 3D Princeton Ocean Model (POM). We forced the hydrodynamic model with observed satellite data obtained from January 2000 to December 2010. The IBM-POM models considered two transport scenarios: (1) passive Lagrangian transport and (2) Diel Vertical Migration (DVM). The results show a high retention on actual and putative nursery grounds that could retain paralarvae in a suitable environment for survival, growth, and ultimately to recruit to the adult population. Moreover, model outputs showed high correlation between autumn-winter retention indexes and spring-summer commercial and artisanal landings in the following year. Considering the nine-month post-hatching lifespan of the species, autumn-winter retention indexes potentially provide forthcoming adult biomass predictions.