Age and growth of whitemouth croaker (Micropogonias furnieri) larvae and juveniles

Abstract

With the aim of studying the age and daily growth of whitemouth croaker (Micropogonias furnieri) larvae and juveniles, the microstructure of sagittae otoliths of 122 individuals 3-25 mm standard or notochord length (SL or NL) size range and 7-92 days old was analyzed. Specimens derived from the turbidity front of the Río de la Plata area, the main spawning zone of the species. Counting and measuring of the increments width along the otolith major radius were performed. The length-at-age data were fitted to the linear model (R² = 0.875) and that of Laird-Gompertz (R² = 0.881) with L₀ = 2.44 and 2.76 mm, respectively, that represents the average length at hatch. With the Laird-Gompertz model an inflection point at 31 days and 10.23 mm SL was obtained. The instantaneous growth rates as a function of length showed a bell shape with an increment of 0.19-0.28 mm day^-1 (27 mm SL asymptotic length). The growth rate derived from the linear model was 0.25 mm day^-1. A linear relationship between the otolith major radius and length was found. The analysis of increments width as a function of age showed a trend similar to the one described in the Laird-Gompertz model.