Daily growth patterns of juveniles and adults of the Peruvian anchovy (Engraulis ringens) in northern Chile

The Peruvian anchovy (Engraulis ringens) is a resource of considerable economic importance, whose stock unit is distributed between 16°00′S and 24°00′S and is shared between Chile and Peru. In the present study, daily growth patterns of juvenile and adult Peruvian anchovies in northern Chile were determined using micro-increments of sagittal otoliths for the recruitment and fishery seasons of 2009 and 2010. A characteristic feature was the existence of very distinctive daily micro-increments, through which a complete sequence of micro-increments was obtained from the primordium to otolith edge for juveniles (7.5-12-cm total length (TL)) and adults (12.5-18.0cm TL), whose ages were in the range 56-166 and 137-409 days respectively. Hatch dates extended from July 2009 to July 2010, where juveniles recruited to a fishery in a given month were the survivors of a spawning that had occurred approximately 3-4 months before. A Laird-Gompertz model fitted to length-at-age data for juveniles estimated maximum instantaneous growth rates that ranged from 0.98 to 1.57mm day-1, whereas overall mean individual growth rates back-calculated for the age range of juveniles ranged from 0.65 to 1.02mm day-1. The von Bertalanffy seasonal parameters estimated through the entire life history showed high growth, with a growth coefficient K≤1.1 and mean length at the first year of 16.3cm TL. Consequently, E. ringens in northern Chile seems to maximize growth in the first year of life.