MEPS 658:181-194 (2021)  -  DOI: https://doi.org/10.3354/meps13548

ABSTRACT: The Peruvian anchoveta Engraulis ringens is one of the most important commercial fishes along the Humboldt Current. Previous studies have shown that egg quality (volume, protein and lipid content) and hatching rates decrease during the spawning season, from the rainy winter to late spring. In this study, we assessed whether changes in atmospheric condition that led to an intense drought over a decade modified the freshwater river fluxes and seawater salinity at an E. ringens coastal spawning zone off central Chile (36° 30’ S), and determined if changes in salinity affect the hatching-gene expression, hatching-enzyme expression, and hatching success in eggs incubated at a range of salinities (27-35 psu) normally occurring during the reproductive season. Results showed that hatching-enzyme expression increased as the embryo developed. The highest expression of the hatching-enzyme gene and of the enzyme itself, along with hatching success were obtained at the lowest incubating salinity (27 psu). In the field, hatching success decreased from late winter to late spring, the start of the upwelling period at the end of the reproductive season. Thus, variations in salinity of the seawater during the spawning period are coincident with changes in gene expression of the hatching enzyme, the hatching enzyme expression, and hatching success. Spawning late in winter when rainfall is higher and seawater salinity in the coastal area is lower may increase hatching success, a reproductive strategy that might be affected by the observed climate changes and severe drought in central Chile.

KEY WORDS: Anchovy · Hatching · Hatching enzyme · Small pelagic fishes · Humboldt Current