prey. A possible commensal is the bacterium Colwellia asteriadis, a new species published in 2010, which has only been isolated from Asterias amurensis hosts in the sea off Korea. These showed no effects from hosting the bacteria. Impacts Traditional medicine It is considered useful in traditional medicine in China and is in the 2015 Pharmacopoeia of the People's Republic of China no. Impacts on mariculture It is a predator which can impact the abundance of juvenile bivalves. The asteroid stage can attach itself to salmon traps, oyster lines and scallop longlines. In Japan, where it is native, population outbreaks have cost the mariculture industry millions of dollars in control measures and losses from predation. It can have significant impact on Mizuhopecten yessoensis scallop plantations and populations of Fulvia tenuicostata and Patinopecten yessoensis in Japan, and some impact on mussels and oysters in Tasmania. Invasive species This seastar is an invasive species in Australia. It has colonised Australian waters in the Derwent Estuary, Port Phillip Bay and Henderson Lagoon in Tasmania. In the Derwent Estuary, the Northern Pacific seastar has been connected to the decline of the endemic endangered spotted handfish. The most likely mechanism of introduction is the transport of free-swimming larvae in ballast water for ships. The ships suck in the ballast water containing seastar larvae, in a port such as one in Japan, and let it out in a port such as one in Tasmania, the larvae come out with the water, and metamorphose into juvenile sea stars. Removal Trials have been run to find effective removal processes including physical removal of A. amurensis, which was estimated by workshop participants to be the most effective, safe and politically attractive when compared with chemical or biological control processes. Several "sea star hunting days" have been organized in Tasmania in which several thousand sea stars have been removed. Mountfort et al. studied developing a probe to test ballast water and detect the presence of this specific maritime pest. Early detection remains the best solution to reducing harmful effects of invasive species. Conservation The population has not been assessed by the IUCN. See also Northern Pacific seastar in Australia Asterias rubens References amurensis Fauna of the Pacific Ocean Animals described in 1871 Taxa named by Christian Frederik Lütken