Use of a fishery model (FAST) to explain declines in the stocked barramundi (Lates calcarifer) (Bloch) fishery in Lake Tinaroo, Australia

Abstract

Electrofishing, a fishery-independent technique, was used to determine the size structure of a stocked impoundment barramundi (Lates calcarifer) fishery in Australia, in order to determine their size and age structure. Along with known recruitment values (stockings), this information was used to back-calculate the mortality on each successive age class of fish. Using the fisher model, Fishery Analysis Simulation Tool (FAST), it was found that the fishery biomass reached a peak in the 1990s, and has since fallen rapidly because of the lack of successful recruitment until 2003. The fishery sampled in 2002 was dominated by older age fish classes (10+ to 14+ years old), which is opposite to that naturally found in wild fisheries. Although no juvenile L. calcarifer was found in the gut contents, cannibalism is suggested as an overriding cause for recent recruitment failure. Possible future management options for stocking apex piscivorous fish species into closed water systems also are suggested.