Some Aspects of Gill Measurement in Relation to the Growth of the Yellowtail Seriola quinqueradiata

Abstract

Measurements of gill filaments and secondary lamellae are described in order to provide fundamental information about the gill area of the yellowtail Seriola quinqueradiata in relation to its growth. The measurements were carried out on 28 yellowtail ranging in weight from 4.3 to 1117g, which were divided into seven stages of growth. Analyses of the allometric relationship between the parameters of filaments and body weight were made in comparison with those of the carp. From the measurements of epithelial layer in the secondary lamellae, diffusing capacity of the gills was estimated with the aid of the Fick equation. Total gill area per unit fish was obtained in relation to body weight as shown in formula of Y=2290X^0.686, (r=0.989). Gill area per unit body weight is great in the early stage of growth, but after stage IV no remarkable changes in gill area are found as a results of growth. Gill area per unit body weight was about 366 mm²/g. In comparison with those of other species, it is supposed that the yellowtail is placed somewhere at the lower end of the group of fast swimming fish.