Growth variation of newly settled winter flounder ( Pseudopleuronectes americanus) in New Jersey estuaries as determined by otolith microstructure

Abstract

In an effort to determine differential patterns of growth for juvenile winter flounder, otolith increments were examined from individuals collected from 4 sites spanning the coastline of New Jersey, U.S.A. (approximately 200 km) in late May 1990. Increment widths in 3 sections of the left sagitta were measured with an image analysis system, and the number of post-metamorphic increments counted. A linear regression equation based on the correspondence between otolith growth and somatic growth was used to calculate daily growth rates from the mean increment width in each otolith section. Fishes collected from the most northern site (Sandy Hook) and a mid-coast site (Great Bay) were significantly smaller in total length than the other 2 sites (Barnegat Bay and Wildwood). Based on increment counts and widths, fishes at Sandy Hook were smaller because they were younger in post-metamorphic age; mean increment counts at the other 3 sites did not differ from each other but were all significantly greater than foe Sandy Hook. In contrast, fishes at Great Bay were smaller because they had a slower growth rate; the other 3 sites had similar growth rates that were all significantly greater than the Great Bay site. Thus, age and growth information recorded in the otolith increments allowed distinction of 2 underlying reasons for different size-frequency distributions.