Estimating rates of mortality in school prawn populations of eastern Australia.
Montgomery SS, Barchia IM and Walsh CT (2011) Estimating rates of mortality in school prawn populations of eastern Australia. Fisheries Research, 113: 55–67.
School prawns, Metapenaeus macleayi, are one of two species that combined make up more than 90% of the commercial landings of prawns in New South Wales each year, but little is known about the rates of mortality of this species. This paper reports on the first estimates of natural and fishing mortality for school prawns. The research was part of a four-year study into the growth and mortality of school prawns jointly funded by Industry and Investment NSW, Fisheries Research and Development Corporation. Rates of fishing mortality were determined from repeated tag-recapture experiments in Wallis Lake and the Clarence River whereas natural mortality was calculated by using the known relationship between life history and natural mortality in other species. Rates of fishing mortality in the Wallis Lake stock and in the Clarence River stock in 2004-05 and natural mortality for both stocks were comparable to those reported for other penaeid fisheries world wide. Rates of fishing mortality in the Clarence River stock in 2005-06 were higher than found for other prawn species possibly because high rates of river discharge affected prawn behaviour. Natural mortality and fishing mortality were greater for the Clarence River than the Wallis Lake stocks. These results will contribute to the management of the school prawn stocks as input data to yield per recruit and length-based population modelling.