right|thumb|The Northern Pacific starfish (Asterias amurensis).
The Northern Pacific seastar (Asterias amurensis) is an invasive species in Australia.
Background
This seastar is native to the coasts of northern China, North Korea, South Korea, Russia and Japan, and distribution of this species into other countries has increased. It is on the Invasive Species Specialist Group list of the world's 100 worst invasive species. They can be transmitted to waters around the world via seawater in live fish trade, via recreational boats, in ballast water, and on the hulls of ships.
The species prefers waters temperatures of 7°C to 10°C, but it has adapted to Australian waters of around 22°C, and usually found in shallow waters of protected coasts. It is able to tolerate a wide range of temperature and salinity, so is frequently found in estuaries and on muddy, sandy or rocky sheltered areas of intertidal zones. Their presence has been recorded in the state from as far north as Banks Strait (between Cape Portland and Clarke Island) and south to Recherche Bay, with the highest population densities in sheltered waters in south-east Tasmania, particularly the Derwent Estuary.
In Australian waters, spawning occurs between July and October,
A. amurensis is included in Australia’s Priority Marine Pest List, and in 2019 was listed as an Australian pest species of national priority, owing to its impacts on aquaculture, commercial shellfish industries and its impact on the critically endangered spotted handfish (Brachionichthys hirsutus).
Marine biologists hope that diseases or sterile seastars may be introduced in the future. However, many of the seastars that were captured were cut up and thrown back into the sea, and it was later found that each part that was thrown back was able to regenerate and grow a new organism, so long as it had part of the central disc remaining.
a new push is being led by local diver Benni Vincent, who intends to organise two to three dives a month over a period of three to five years, concentrating on the areas where the populations are highest, as well as in areas where the handfish live.