The effects of freezing on the morphometrics of sardine Sardinops sagax (Jenyns, 1842)

Abstract

The effects of freezing on the morphometrics of sardine Sardinops sagax were studied. Results were variable depending on the length of the freezing period, but all fish showed significant ( p < 0.001) decreases in both caudal length and wet body weight compared to initial measurements taken from unfrozen fish. The absolute weight loss of sardine ranged between 0.256 and 0.868 g, which corresponded to a relative weight loss between 0.86 and 2.49%. The absolute loss in caudal length ranged between 0.281 and 0.458 cm, whereas the relative loss in caudal length ranged between 1.57 and 2.54%. The effect of freezing duration on morphometric measurements was variable, and whereas shrinkage was most common, no effect was observed in a number of cases. Most of the morphometric measurements showed small changes and, if they decreased, the decrease was gradual. Only one morphometric measurement (LM 12, the distance between the snout and the top of the head) showed a significant increase in half of the eight freezing periods. The relevance of these results to studies of morphological variability in fish is discussed.