Gold clams off the menu

Tuesday, 22 August 2023

Mighty River Domain manager Liz Stolwyk with some invasive gold clams found in Lake Karāpiro last week.

How would you like your aquatic pest served, madam - in fritters, steamed or a stir-fry?

While you probably won’t hear those words in any New Zealand restaurant, the country’s latest unwanted resident - the freshwater gold clam - is considered a food source in many parts of southeast Asia.

But, top Kiwi chef Al Brown said he probably wouldn’t waste his time cooking them and Biosecurity New Zealand (BNZ) considers them toxic and has advised the public not to eat, or even remove them, from the Waikato River.

Top Kiwi chef Al Brown said the clams would not have much flavour, because that usually comes from the salt water.

Gold clams were first found at Bob’s Landing, near Lake Karāpiro on the Waikato River, in May and have since spread up-river as far as Mangakino and have also been detected near Port Waikato.

Last week, the gold clam was officially classified as an “unwanted organism” and it is illegal to “knowingly move or spread the freshwater gold clam or water that may contain it”.

Also known as the prosperity clam, pygmy clam, or good luck clam, a market exists for them in Japan, China, and other countries in the region including Malaysia, Vietnam and Thailand.

It’s not safe to eat clams collected from an area where there’s a lot of bacteria and contaminants, or where pollution is suspected, Biosecurity NZ says (file photo).

Brown said the first idea that came to mind, when approached by the Waikato Times, was to turn them into fritters.

“But they won’t have a lot of flavour being from fresh water, instead of from salt water, which is where you get all those flavours.

“Maybe put them in some fritters to jazz them up a bit. They won’t do well in a chowder because there would be so little flavour.”

Brown said they would also go well in a Chinese-style dish with fermented black beans and ginger, but they’re small so he’d most likely go for a larger salt-water mollusc.

A quick internet search found a range of recipes for gold clams. Most were for stir fries, and they can also be steamed with ingredients such as garlic and ginger.

Culinary capers aside, BNZ deputy director-general Stuart Anderson said no-one should be eating them as they had been found in areas with “higher levels of bacteria from combined discharges, including storm-water run-off and sewage treatment plants”.

“Freshwater gold clams are bivalves and although bivalves themselves are not toxic, they can ingest harmful algae or other environmental contaminants and retain it in their flesh that can then be passed on to anything or anyone that eats freshwater gold clams.”

He said the clams had not been tested for their toxicity, but he’d give the same advice to people eating freshwater mussels or any shellfish.

“It would be unsafe to eat them when they are collected from an area where levels of bacteria and contaminants would be high, and/or there is a suspected pollution.”