As Australia grapples with the economic and environmental cost of biosecurity failures including fire ants, varroa mite and carp, another introduced marine pest has been quietly spreading.<\/p>\n
Authorities are calling for the public’s help to determine the distribution of a supersized, swift-growing, sex-switching oyster with the potential to invade much of the nation’s coastline.<\/p>\n
<\/p>\n
Suminoe oysters attached to a discarded fan, besser brick and boat. (Supplied: DPI\/Queensland government)<\/p>\n
Widely farmed across China, Japan, India and Pakistan, Magallana ariakensis, the Suminoe or Chinese river oyster, is more than just a mouthful to pronounce.<\/p>\n
The rapidly spreading species can grow up to 24 centimetres long, reaching harvestable size in as quickly as 15 months, compared to two and a half to four years for a native Sydney rock oyster.\u00a0<\/p>\n
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Mature Suminoe Oyster (left), native Sydney rock oyster (middle) and juvenile Simone oyster. (Supplied: DPI\/Queensland government)<\/p>\n
Known invasion sites<\/p>\n
Authorities believe Suminoe oysters hitchhiked into south-east Queensland on vessels travelling from overseas.<\/p>\n
The pest was first found in Bribie Island’s canal system in June 2023 but Biosecurity Queensland (BQ) said their size and population indicated they could have arrived at least three years earlier.<\/p>\n
The invasive oyster has since been detected in estuaries in Moreton Bay, including Brisbane’s Kedron Brook, and Boggy Creek near the mouth of the Brisbane River at Pinkenba.<\/p>\n
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The invasive oysters are outcompeting native species. (Supplied: DPI\/Queensland government)<\/p>\n
It has not been reported in New South Wales but monitoring will be crucial for early detection and management.<\/p>\n
The full extent of its spread in Australia is difficult to determine because Suminoe oysters are often covered in algae and proved initially hard to distinguish from other shellfish.<\/p>\n
<\/p>\n
Anita Wohlsen is asking people to report giant oyster sightings. (Supplied: DPI\/Queensland government)<\/p>\n
Invader hiding in plain sight<\/p>\n
BQ principal officer of marine biosecurity Anita Wohlsen said the first sign of the pest was their large size.<\/p>\n
“They have flaky kind of shells, which are a bit different to the natives, and that becomes more apparent as they become bigger,” Ms Wohlsen said.<\/p>\n
The invader’s inner shell lacks the little ridges common to native oysters and has a distinctive purple to black scar.<\/p>\n
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The inner shell of the invasive oyster has a distinct purple to blackish scar. (Supplied: DPI\/Queensland government)<\/p>\n
The oysters attach to submerged and floating infrastructure, including pylons, pontoons and boats, and can occupy shallow waters and muddy creeks.<\/p>\n
Ms Wohlsen said they could carry disease and threaten native shellfish species.<\/p>\n
“They compete with our native species for habitat and they can also foul infrastructure, which leads to increases in costs,” she said.<\/p>\n
<\/p>\n
Suminoe oysters are considered a biosecurity threat. (Supplied: DPI\/Queensland government)<\/p>\n
BQ is now calling on commercial and recreational fishers to inspect, clean and dry vessels, equipment and gear before moving to a different location.<\/p>\n
That includes hulls, pots, nets, fishing or diving gear, anchors and ropes.<\/p>\n
Sex-switching abilities<\/p>\n
Suminoe oysters can reach sexual maturity in two to three months compared to three years for Sydney rock oysters.<\/p>\n
They are protandric hermaphrodites, which means they start life as males, then can switch to become females.<\/p>\n
“They reproduce very effectively, which makes them good invaders,” Ms Wohlsen said.<\/p>\n
“They can spread quite quickly and their populations can grow quite quickly.”<\/p>\n
<\/p>\n
ABARES modelling for the potential spread of the Suminoe oyster. (Supplied: ABARES)<\/p>\n
Vast potential invasion zone<\/p>\n
Modelling by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) was published in August 2024.<\/p>\n
It found the Suminoe oyster could potentially infest most of Australia’s coastline, except for Victoria, Tasmania and parts of the south coast of Western and southern Australia.<\/p>\n
Adults can tolerate temperatures between 0\u201335 degrees Celsius.<\/p>\n
Their larvae or spat can survive in waters between 20\u201330C in the crucial two to three weeks when they are carried in currents to find a suitable hard surface to attach to.<\/p>\n
<\/p>\n
Carol Booth says the full impact of the oyster is unknown. (Supplied: Invasive Species Council)<\/p>\n
The Invasive Species Council of Australia said the long-term environmental impact was hard to estimate.<\/p>\n
“It [Suminoe oyster] could introduce new parasites or pathogens that might spread to native species,” senior policy advisor Carol Booth said.<\/p>\n
With doctorates in biology and environmental philosophy, Dr Booth said biosecurity funding and staffing in general had failed to keep pace with increased marine traffic and imports.<\/p>\n
“We’re in the midst of a giant ecological experiment with new species coming in,” she said.<\/p>\n
<\/p>\n
The invasive oysters grow much faster than native oysters. (Supplied: DPI\/Queensland government)<\/p>\n
Illegal to eat in Australia<\/p>\n
The Suminoe oyster is a prized aquaculture species overseas, praised for its plump, creamy texture and salty, smooth taste.<\/p>\n
But in Australia, they are listed as biosecurity matter, making it illegal to take them, use them for bait or eat them.<\/p>\n
Those in breach of the law could be fined.<\/p>\n
BQ said Suminoe oysters living in habitats surrounded by urban development would be risky to consume.<\/p>\n
“They are filter feeders and bioaccumulators; they can accumulate heavy metals and other things that may be in the water,” Ms Wohlsen said.<\/p>\n
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The invasive Suminoe oyster is hard to identify until it grows. (Supplied: DPI\/Queensland government)<\/p>\n
To help monitor their spread, BQ has been training OzFish volunteers and oyster restoration groups in south-east Queensland to identify Suminoe oysters.<\/p>\n
Potential sightings can be reported, with people encouraged to record the location and take a photo, if safe.<\/p>\n
<\/p>\n
Andrew Robson says the Suminoe oyster could present aquaculture opportunites. (ABC Landline: Cameron Lang)<\/p>\n
More investigation needed<\/p>\n
However, some predict there could be positives in the fast-growing, fertile shellfish.<\/p>\n
The Queensland Oyster Growers Association said Australian authorities should test their aquaculture potential given the increasing challenges with farming oysters due to climate change, pollution, disease and flooding.<\/p>\n
“If it’s showing QX [disease] resistance, if we have changing water temperatures over time with climate change, and it’s stabilising and setting up well, it may lead to a farming option,” association president Andrew Robson said.<\/p>\n","protected":false},"excerpt":{"rendered":"As Australia grapples with the economic and environmental cost of biosecurity failures including fire ants, varroa mite and…\n","protected":false},"author":2,"featured_media":128760,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[64,63,89753,9326,50999,89752,75,89749,89751,8969,29151,89750,128,89748],"class_list":{"0":"post-128759","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-au","9":"tag-australia","10":"tag-australian-bureau-of-agricultural-and-resource-economics-and-sciences","11":"tag-biosecurity","12":"tag-biosecurity-queensland","13":"tag-chinese-river-oyster","14":"tag-environment","15":"tag-giant-oyster","16":"tag-invasive-oyster","17":"tag-invasive-species","18":"tag-invasive-species-council","19":"tag-pest-oyster","20":"tag-science","21":"tag-suminoe-oyster"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/128759","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=128759"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/128759\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/128760"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=128759"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=128759"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=128759"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}