Taxonomy of Finfish

2.3.1 Morphometrics

The morphometric characters are measurable features. These characters have been helpful for separating closely related genera and species and even population within species and are used in ichthyotaxonomical studies.

Measuring the linear dimension of whole or parts of finfish is probably the most widely used technique in finfish taxnonomy. The commonly used length measurements in finfishes are (i) total length, (ii) standard length and (iii) fork length. Of these, the most frequently chosen one is total lengtth, because it is quick and easy to measure. Further, total length has been related to many factors such as weight, age, fecundity, maturity, etc. These parameters should be easily assessed in relation to total length.

Though total length is the easiest to measure, in larger species with a deeply forked caudal fin, such as in scombrids, carangids, etc., fork length is preferred. Though standard length is used by ichthyotaxonomists, in large specimens standard length is not used because of the difficulty in ascertaining the posterior margin of the hypural plate.