Patagonian grenadier (Macruronus magellanicus) is widely distributed around the austral zone of South America. Contrary to the South Atlantic, a large number of eggs and larvae have been observed in the Chilean Patagonia. The spatial and temporal stability of these spawning areas, however, has not been confirmed, nor have their environmental features been detailed. To characterize the spawning and nursery areas of M. magellanicus, we analyzed zooplankton samples and hydrographic data collected during winter and spring in the inner sea (inshore) and its adjacent continental shelf (offshore) of the Chilean Patagonia between 1995 and 2019. The results indicate that northern Chilean Patagonia is a key spawning and nursery area for this species. Peak spawning occurs in winter, most eggs are found offshore, and secondarily inshore, between 44°-46°S, whereas toward southern Patagonia, the limited spawning observed appears to occur within the inshore zone areas. A fraction of the spawn located offshore in the northern Patagonia enters the inshore areas and, as their larvae grow, they return to the offshore zone. A linear relationship was found between salinity and egg abundance, coinciding with a deeper vertical distribution, whereas a non-linear (dome-shaped) effect of temperature on larval abundance indicated a wider spatial distribution. Overall, both egg and larval abundances declined over the 25-year study period.
