Deepening our understanding of the environmental influences on the reproductive dynamics of the main fishery stock of Argentine hake, Merluccius hubbsi , in the southwestern Atlantic Ocean

Abstract

This study analyzed the inter-annual variability in the reproductive dynamics of theArgentine hake from Patagonian waters during the last 20 years concerning the envi-ronmental conditions and the nutritional status of females. Macroscopic and histolog-ical information on gonadal maturity, female condition factor (K), and oceanographicdata at different sampling sites throughout the studied region were obtained fromresearch surveys carried out during the main spawning season of this species. Fourstages, according to the maturity ovarian phases composition, were assigned annuallyat each sampling site to assess reproductive dynamics: vitellogenesis, ovulation,regression, and resting. The spatial pattern of inter-annual variability in reproductivedynamics was described, and the influence of temperature and female condition onthe probability of ovulation and regression was assessed using generalized linearmodels. The area with the lowest inter-annual variability in the hake reproductivedynamics was observed between 43 and 45S (50 to 80 m depth) in relation to ovula-tion events. The vitellogenesis stage was more frequently found adjacent to thereproductive area, whereas the regression was mainly observed in deeper waters.Both bottom and surface temperatures explained the ovulation and regressionstages, showing a positive and negative relationship, respectively. Lower values ofthe K factor, associated with low food availability, were further linked to the occur-rence of regression. Finally, it is worth noting that the relationship observed betweenthe ovulation/spawning dynamics of Argentine hake and water temperature suggeststhat the reproductive success of this species could be affected in the future scenarioof climate change.