Habitat History of BarramundiLates calcariferin a North Australian River System Based on Barium and Strontium Levels in Scales

Abstract

The barramundi Lates calcarifer is a large centropomid fish that utilizes freshwater and saltwater habitats and is generally regarded as catadromous. It is fished commercially in coastal waters in northern Australia. It is also a popular recreational species in fresh and estuarine waters, and has been the subject of a resource allocation controversy in recent years. The possible existence of purely marine populations of barramundi in waters adjoining the Mary River system was examined through a chemical analysis of scales by means of inductively coupled plasma atomic emission spectroscopy. Discriminant function analysis with control fish reared in freshwater and salt water showed that wild barramundi could be classified reliably by barium and strontium levels, which are related to environmental history. Cluster analysis indicated that there were probably marine, mixed, and freshwater groups. We conclude that most barramundi found in areas remote from freshwater parts of the Mary River system probably had no freshwater phase. Commercial use of such stocks may not have a major impact on the recreational sector, which operates mainly in fresh and upper estuarine waters.