Post mortem shrinkage of four species of temperate and tropical marine fishes, without freezing or preservation

Abstract

The present study indicated significant post mortem decreases in length for four Australian teleost species from temperate to tropical habitats: black bream Acanthopagrus butcheri, King George whiting Sillaginodes punctata, summer whiting Sillago ciliata and redthroat emperor Lethrinus miniatus. Shrinkage averaged 5·0 mm after 24 h (range 0–10 mm) for A. butcheri, 4 mm (0–8 mm) for S. punctata, 2·2 mm (0·7–3·7 mm) for S. ciliata and 5·4 mm (−2·5–15·0 mm) for L. miniatus. For A. butcheri held under three different post mortem treatments, the mean length of fish in all treatments decreased but there was no significant effect of treatment type on the extent of shrinkage. The rate of shrinkage of S. ciliata varied with treatment, but the ultimate extent did not. For A. butcheri shrinkage was most rapid (2·5 mm h−1) between 1 and 2 h postcapture. The results from these studies confirm that a post mortem decrease in length is a common phenomenon, even in fishes that are not frozen or preserved. Such shrinkage has implications for the enforcement of minimum legal length legislation, and may cause bias in biological investigations, including growth estimates from tag and recapture studies.