Somatic growth and otolith growth in juveniles of a small subtropical flatfish, the fringed flounder, Etropus crossotus.

A growth experiment was conducted with juvenile fringed flounder (Etropus crossotus) from North Inlet (South Carolina, USA) to provide information on the growth of a small, shortlived flatfish with a subtropical and tropical distribution. The fringed flounder has a maximum life span of 1.5 y and its long spawning period from March through October complicates the determination of growth rates based on length frequency data. Otoliths of juveniles with a standard length (SL) 23.1-53.0 mm were marked with Alizarin complexone and the fish were held in the laboratory for 66 days at 14, 20, 24 and 29 degrees C while being fed ad libitum. The mean somatic growth increased with temperature from 0.1 mm SL day(-1) at 14 degrees C to 0.4 mm SL day(-1) at both 24 and 29 degrees C. The maximum observed somatic growth rate was 0.7 mm SL day(1) at 29 degrees C. The number of micro-increments formed in otoliths was not significantly different from the expected value, validating formation of one increment per day. The significant relationship between increment width and somatic growth rate can be used to estimate somatic growth rates of individual wild fish based on daily increment information in their otoliths.