Dynamics of Capelin during the First Year of Life Highlight High Connectivity Between the Saguenay Fjord, the Saint-Lawrence Estuary and the Gulf

Capelin (Mallotus villosus) is a key forage species in the Saguenay – St. Lawrence Marine Park (SSLMP) that includes a large portion of the St. Lawrence Estuary (SLE) and nearly the entire Saguenay Fjord (SF). Little is known about sources of capelin in the SSLMP, whether they recruit locally through larval retention or derive from other spawning sites, beyond the boundaries of the Park in the SLE and the Gulf of St. Lawrence (GSL). Our aim is to identify sources of 1 year-old juvenile capelin found in the SSLMP. Elemental fingerprints in larval otoliths (n=280, caught in SF, SLE and GSL in 2009) and juveniles’ otolith cores (n=35, caught in SSLMP in 2010) were related to spawning sites. Elements along the entire juvenile’s otolith explained larval dispersion and migration. Analysis was performed using a LA-ICP-MS. Sources were found everywhere in the Fjord-Estuary-Gulf system. However, similar dispersion patterns were observed. Larvae first drifted to high salinity areas for few weeks. Then, they moved towards brackish waters retention areas. Thereafter, they were found in the GSL during winter. Subsequently, juveniles migrated to the SLE and the SF. Capelin dynamics highlight a high connectivity throughout the system, both at larval and juvenile stages.