Movement and Growth of Penaeus Esculentus (Haswell, 1879) Estimated from Tagging in Torres Strait

K. Derbyshire, D. Sterling, R. Watson, A. Lisle, (1990). “Movement and Growth of Penaeus Esculentus (Haswell, 1879) Estimated from Tagging in Torres Strait,” Torres Strait prawn project: A review of research 1986-88 (Queensland Fisheries, Brisbane, Australia). Chapter 7.

Some of the most important factors in managing a fishery are: an estimate of the relative abundance of the population, the age/size composition of the population, growth rates, age at maturity, and mortality rates from fishing and natural causes (Rounsefell 1975). As juvenile prawns are found in a separate habitat from that of adults, prawn movements are also important to management. Tagging of animals for later recovery is an excellent method for estimating growth rates and migration, and for separating fishing and natural mortality rates (Gulland 1983). In some instances tagging can also be used to estimate population size (Jones 1977). Several assumptions are made concerning tagged individuals. Firstly, that the tagged individuals disperse randomly through the population to be studied before recapture, secondly that the tagged individuals are subject to the same mortality rates as untagged individuals, and thirdly that tags are not lost or overlooked when recovered (Krebs 1978). In some circumstances it is impossible not to violate one of these assumptions. Tags are known to affect speed of movement, susceptibility to predation, feeding ability and mortality (Rounsefell 1975). Despite these violations, tagging is the most reliable method for estimating growth in Penaeidae (Garcia and Le Reste 1981 ). Another reliable application of tagging experiments is to quantify the movement of tagged animals. A knowledge of migration patterns is an essential component in the identification of stock boundaries (Somers and Kirkwood 1984), an issue of importance for the Torres Strait Prawn Fishery which has catch sharing arrangements between two countries, Australia and Papua New Guinea. The initial objectives of this tagging programme were to describe the movements and growth of Penaeus esculentus, the brown tiger prawn.