Seasonal and spatial variability in condition of age‐0+ Argentine hake Merluccius hubbsi Marini, 1933, in the San Jorge Gulf (Argentina): A bottom‐up perspective

MARTOS, PATRICIA; MASSA, AGUEDA E.; TEMPERONI, BRENDA; MARRARI, MARINA

FISHERIES OCEANOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 29 p. 597 - 611

1054-6006

In the north Patagonian region of the Argentinean Continental Shelf, the San JorgeGulf (SJG; 45°-47°S, 65°30ʹ-67°30ʹW) is the main nursery ground of age-0+ Argentinehake Merluccius hubbsi Marini, 1933, one of the most important fishery resources inArgentina. The gulf exhibits strong seasonal and spatial fluctuations in environmentalfeatures, which might affect survival of age-0+ individuals and recruitment to theadult population. Our main goal was to evaluate the seasonal and spatial dynamics oftheir nutritional status within the SJG in winter 2016, spring 2016 and summer 2017.Condition indices (relative condition factor Kn, hepatosomatic index HSI and liverlipid content %L) and diet information (feeding incidence and relative importance ofprey) were combined with physical (temperature and salinity) and biological (satellitechlorophyll-a concentration; chl-a) data. Age-0+ condition indices and prey intakeshowed significant seasonal variations, with minimum values in winter, intermediatein summer and maximum in spring, strongly coupled to the mean chl-a concentrationin each season. Herbivorous euphausiids Euphausia spp. were the preferred preyalong the study period. A bottom-up effect on condition of age-0+ hake is suggested,manifested as lower condition values in winter, the less productive season. Spatially,better conditioned individuals matched sectors of the gulf where chl-a concentrationswere higher, coupled to the presence of frontal systems. Monitoring age-0+hake nutritional status is relevant in the current global change scenario, which mightmodify phytoplankton biomass and composition and, consequently, the herbivorouszooplankton abundances.