An assessment of the use of short-term closures to protect spawning southern calamary aggregations from fishing pressure in Tasmania, Australia

Fishing effort for southern calamary in Tasmania focuses on the spawning aggregations that occur in shallow sheltered bays over the austral spring and early summer. This paper explores the effect of two 2-wk fishing closures in Great Oyster Bay, Tasmania to protect spawning populations of the southern calamary squid (Sepioteuthis australis) from fishing pressure. In the period before the first 2-wk closure, mature adult squid were present on the inshore seagrass beds in which they lay their eggs. However, despite the high reproductive status of the females present very low numbers of eggs were laid. During the first of the two closures, densities of eggs increased six-fold, suggesting that either the closure provided protection to the spawning aggregation or promoted an increase in spawning activities. An increase in spawning activity did not occur during the second closure, possibly because the reproductive condition of females was declining by this time. However, densities of newly laid eggs on the seagrass beds remained constant during the following 6 wks. Daily CPUE information suggested that closing Great Oyster Bay to fishing did not result in increased numbers of squid aggregating in the spawning areas. Despite increased commercial fishing effort throughout Tasmania, CPUE data indicates higher catches of squid were landed in Great Oyster Bay. However the reduced contribution of Great Oyster Bay to total catches in Tasmania over the study period suggests the short closures were of value in protecting the spawning aggregation.