MORPHOLOGICAL VARIATION IN THE CATADROMOUS AUSTRALIAN BASS, FROM 7 GEOGRAPHICALLY DISTINCT RIVERINE DRAINAGES

The Australian bass Macquaria novemaculeata is a catadromous species r estricted to coastal drainages of south-eastern Australia and recently has undergone reductions in population numbers. Morphometric variatio n among bass from seven distinct drainages was used to test for the pr esence of stock structuring. Males and females were treated separately . For both male and female bass, significant heterogeneity in morpholo gy among sample locales was revealed by univariate statistics and disc riminant function analysis, with morphological variation found to diff er in a clinal pattern. The demonstration of population-specific morph ological traits among bass from different river drainages may indicate that interpopulational movement is restricted and that each sample lo cale constitutes a separate stock of bass. (C) 1998 The Fisheries Soci ety of the British Isles.