Trophic niche changes during settlement in the Argentine hake Merluccius hubbsi reveal a prolonged importance of pelagic food post-metamorphosis

BOTTO, F; GAITÁN, E; IRIBARNE, OO; ACHA, EM

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Año: 2019 vol. 619 p. 125 - 136

0171-8630

Among those factors thatdetermine the success of a fish cohort, trophic interactions play a key role,especially during the larval and juvenile stages. The Argentine hake Merluccius hubbsi isthe most abundant demersal fish in the southwestern Atlantic and also one ofthe main commercial resources for Argentina. By employing C and N stableisotope analysis, we evaluated M. hubbsi changes in trophic nicheand trophic position throughout their early life from early larvae to juveniles2+ (8−330 mm total length, TL) during their drift from the spawning to thenursery ground. We analyzed 121 individuals and 7 possible resources indifferent sectors as fish move from the spawning to the nursery ground in thecoastal region of northern Argentine Patagonia. Our results show that Argentinehakes occupy different trophic niches during their ontogenetic development.While larval stages (8−34 mm TL) feed almost exclusively on copepods, largerjuveniles showed shrimps as their main prey. Individuals between 35 and 89 mmTL showed the most generalist diet, with a mix of both pelagic and epibenthicprey. Therefore, our results indicate that the change from a planktonic to ademersal habitat (settlement), which is of paramount importance in the earlylife history of hakes, is a gradual process.