Energy density of sub-Antarctic fishes from the Beagle Channel

Abstract

The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principal-components analysis (PCA) of the ED of the different organs/tissues indicated that PC and PC accounted for 87% of the variability. Separation along PC 1 corresponded to differences in muscle and liver energy densities whereas separation along PC corresponded to differences in the ED of the gonads. Differences between species were significant except for P. sima. Inclusion of the gonadosomatic index (GSI) as an explanatory variable enabled us to establish the existence of energy transfer from muscle and liver to the gonads in ripe P.tessellata females. Total ED values varied between 4.21 and 6.26 kJg, the pelagic Odontesthes sp. being the species with the highest ED. A significant relationship between ED and muscle dry weight (DW) was found for all the species except P. tessellata. These data are the first direct estimates of ED of fishes from the Beagle Channel.