Morphological variation in the catadromous Australian bass, from seven geographically distinct riverine drainages

The Australian bass Macquaria novemaculeata is a catadromous species restricted to coastal drainages of south-eastern Australia and recently has undergone reductions in population numbers. Morphometric variation among bass from seven distinct drainages was used to test for the presence of stock structuring. Males and females were treated separately. For both male and female bass, significant heterogeneity in morphology among sample locales was revealed by univariate statistics and discriminant function analysis, with morphological variation found to differ in a clinal pattern. The demonstration of population-specific morphological traits among bass from different river drainages may indicate that inter-populational movement is restricted and that each sample locale constitutes a separate stock of bass.