Comparative morphology of wild, farmed and hatchery-released gilthead sea bream (Sparus aurata) in western Greece

Abstract

In May 2001, 60,000 individuals of gilthead sea bream (Sparus aurata) fry, originating from a common
bloodstock of the Ionian coastal region, were allocated between Papas lagoon and cages of mariculture
enterprises located at Western Greece. During the period of November to December 2001, a sample of 531
gilthead sea bream individuals was collected from the lagoon and the cages. The variations in 24 morphomertic
characters and in two indices (condition factor and gonadosomatic index) were examined using multivariate
analysis, in order to evaluate the morphological similarity/dissimilarity between hatchery-released (EN), wild
(WL) and farmed (RR) individuals. Statistically significant differences were observed among the groups in mean
and standard deviation values for most of the morphometric characters, a fact that can be possibly attributed to
the life-history of the fish. Principal component analysis along with discriminant analysis identified that the
characters of primary importance in distinguishing the three groups were those related to head, fin and
lengthwise dimensions. Discriminant analysis also revealed that about 86.1% of the examined specimens could
be correctly classified in the three groups. The above findings can be useful for scientific but also for
commercial reasons, since the market value of the fish is highly dependant on its origin