Potential for biocontrol of the exotic starfish, Asterias amurensis, using a native starfish

Abstract

Asterias amurensis is a starfish native to the northern Pacific that was introduced into southern Australia in the 1980s. It is widely viewed as one of Australia’s most serious invasive marine pests, but there are few methods available to control new or established populations. The role of Coscinasterias muricata in controlling the distribution of Asterias in Port Phillip Bay, and its potential to eliminate new infestations of Asterias were investigated. Laboratory feeding trials, where alternative mussel prey were available, showed Coscinasterias consumed Asterias at the rate of ~45/year. Field surveys in Port Phillip Bay showed that most Coscinasterias occurred at depths shallower than 15 m, while most Asterias occurred at depths greater than 15 m, and the ratio of Asterias/Coscinasterias only exceeded 45 at depths greater than 15 m. Consequently, if laboratory and field feeding rates are similar, Coscinasterias would be expected to exert significant control over Asterias populations at depths shallower than 15 m, and augmenting Coscinasterias populations at sites of new Asterias infestations may help eliminate newly-established populations.