Quality of the reef fish Upeneus tragula (Mullidae) at settlement: is size a good indicator of condition?

The quality at settlement of the goatfish Upeneus tragula (family Mullidae) was examined from 10 samples collected over 2 summers (1990/1991, 1991/1992), at 1 location near Lizard Island on the northern Great Barrier Reef.Australia.Nine commonly used measures of fish condition were employed: standard length (SL), body depth at the pectoral fin, total lipid content, carbohydrate content, protein content, water content, growth rate, burst swimming speed and Fulton's condition factor (K = weight / S L ~) .High and significant levels of variability were found in all measures of condition over the 10 san~ples.There was no relationship between the age of the fish at settlement and total carbohydrate and lipid content or burst speed of fish.Correlations of measures of condition with fish length were very poor.Specifically, burst speed and stored energy levels (lipids, carbohydrates) had particularly low correlations with fish length ( r < 0.2).An experiment determined that burst speed of a fish at settlement was not related to its feeding history within the larval stage.Feeding history only accounted for 6% of the total variation in burst speeds.Most of the var~abil~ty In measures of condition were due to differences among individuals.The poor correlations between all measures of fish quallty (with exception of morphological measures) suggest no single measure gives an adequate description of a fish's survival potential.Furthermore, this study cautions against the direct transfer of size-based theories of success (i.e.'bigger is better') to the variability within a specific developmental stage.