The freshwater gold clam (also known as the Asian clam, or by its scientific name Corbicula fluminea) is native to eastern Asia but is also widely established in North America, South America and Europe. 

Overseas, these shellfish are a pest species because they reproduce rapidly and can clog up water infrastructure such as hydro-electricity plants, municipal water supply and irrigation systems. They are also potentially a threat to native species, as in large populations they consume a lot of plankton. 

Initial checks have found the freshwater gold clam present over a 45-kilometre stretch of the Waikato River, from 1.5km upstream of Bob’s Landing, just upstream of Lake Karāpiro, and downriver to Hamilton.

Mr Anderson says the plan now is to search further, both within the Waikato River and in other rivers and lakes that are linked through human activity.