Abstract

Acanthopagrus latus and A. schlegeli are phylogenetically closely related. The seasonal occurrence and distribution, age and length at recruitment, growth rate and hatching dates of their larvae were compared by collecting fortnightly specimens from four estuaries on the north-eastern and western coast of Taiwan between September 1997 and August 1998. Age and growth rate were determined from the daily growth increments in otoliths of the larvae. Occurrences of A. latus and A. schlegeli larvae on the western coast of Taiwan were temporally and spatially separated. Recruitment of the former progressed from north to south from November through March, whereas the latter progressed from south to north from December through May. Age and length of the larvae at estuarine arrival were greater in A. latus; these values increased southward for A. latus and northward for A. schlegeli. Age at recruitment was inversely correlated with growth rate which was positively correlated to water temperature. A. latus spawned mainly in autumn, whereas A. schlegeli spawned mainly in spring with a minor spawning peak in autumn. Coastal currents and the spawning behaviour of the adults may influence the geographic gradients of the seasonal occurrence and distribution of the larvae on the western coast of Taiwan.