Comparing early life traits of hakes from Chilean Patagonian fjords inferred by otolith microstructure analysis

Abstract

Comparison of larval growth and back-calculated hatch dates on the basis of microstructure analysis of sagitta otoliths were carried out in wild-caught larvae of three commercially important gadiform fishes from Northern Patagonia, South Pacific, Chilean hake Merluccius gayi, southern hake Merluccius australis, and Patagonian grenadier Macruronus magellanicus. Because of the morphological similarities in their larval stages, we hypothesize that early life traits (ELT) will be different among the hake species in order to avoid/reduce interspecific competition. During October–November 2011, there was differences in the spatial distribution of the surviving larvae from the three species along the inner sea; while larval Chilean hake were concentrated in the warmer and fresher seawaters of the Reloncaví fjord, larval Patagonian grenadier were aggregated southward, in the Ancud Gulf, while larval southern hake were found throughout the area, but in low density. Temporal differences were evident in the back-calculated hatch days among species; larval hakes of genus Merluccius hatched during late October, while larval grenadier hatched between August and September. Estimated larval growth rates differed among hake species; larval M. magellanicus experienced the fastest growth rates (0.334±0.01mmd−1), while larval M. australis experienced growth rates of 0.220±0.01mmd−1, and larval M. gayi showed the slowest growth rates (0.180±0.01mmd−1). Therefore, resource partitioning both in time and space are occurring among early life stages of M. gayi, M. australis and M. magellanicus during austral spring season in Northern Patagonian fjords of Chile.