Assessment of the barramundi fishery in Queensland, 1989-2007

Abstract

The barramundi (Lates ca/carifer) is an important target species for commercial, recreational and Indigenous fishers across northern Australia. In Queensland, barramundi stocks from the Gulf of Carpentaria (GoC) and the east coast (EC) are managed separately. Updated assessments of both the Goe and EC stocks are reported here.
The assessment used catch and effort information from both commercial (CFISH logbooks) and recreational (RFISH surveys) sources. The data were split into six different strata based
on the genetic makeup of the stock, leading to six geographical regions with each having its own aggregated total commercial and recreational catch.
The analysis proceeded in two stages. The first stage was a standardisation of the catch rate per unit of effort (CPUE) to obtain an estimate of the relative changes in abundance over
time. The second stage was fitting a biomass dynamic model to estimate absolute stock biomass and management parameters such as maximum sustainable yield.
The primary conclusion drawn from both the standardisation results and the dynamic modelling results is that the data are of insufficient quality to reliably estimate stock biomass
or management parameters. This conclusion is based on a number of factors, including (but not limited to):
• large fluctuations in the standardised catch rate, which would be biologically
implausible if taken as a reliable index of abundance
• an inability to find model parameters that lead to a good fit (unless certain parameters are taken past biologically plausible limits)
• large uncertainty in parameters estimated from the surplus production model.