Comparison of the lipid and fatty acid composition and content of barramundi, Lates calcarifer (Bloch) from fresh and salt water in north Queensland

Barramundi of similar sizes were collected from five locations in north Queensland between September and December 1996. One fish was collected from each of the three salt water sites (Jacky Jacky estuary, the mouth of the Pascoe River and Salmon Creek). The fish from the Jacky Jacky estuary and the Pascoe River were collected in December, prior to the onset of the monsoonal rains. The sample from Salmon Creek was collected in the late dry season (October).Two freshwater sites were sampled. One fish was captured in September, 60 km upstream from the mouth of the Herbert River, which was well above the influence of salt water. Two fish were collected in October from Black Weir, a freshwater impoundment on the Ross River with no access to salt water. Each fish was killed immediately after capture and a sample of approximately 20g wet weight was taken from the "shoulder" region (behind the head and above the lateral line). The skin and subcutaneous layer were removed and samples were stored at -80°C and later freeze dried to determine water content. Four replicates from each freeze dried sample were analysed at the CSIRO Marine Laboratories in Hobart for lipid class composition and content and fatty acid composition and content. This study was initiated with the following objectives:1. to determine whether there were variations in the lipid and fatty acid composition and content of the catadromous fish, barramundi (Lates calcarifer) from fresh and saltwater regimes.2. to investigate whether any differences could be used to ascertain the environment in which specimens had been recently feeding.