Tasmania Nearly Wipes Out Weed Choking Largest Wetland

For two weeks every year, oyster farmers in Tasmania's far northwest voluntarily stop harvesting nearly half a million dollars worth of shellfish so their wetland can heal.

They're part of an ambitious 15-year mission that's finally paying off. Circular Head Landcare set out not just to control rice grass, an invasive weed choking 120 kilometers of coastline, but to eradicate it completely.

The numbers tell an incredible story. What started as 50 hectares of dense, knee-high grass has shrunk to just 5 hectares. Fish species jumped from 5 to 11 in just a few years.

"After two years, three years, you wouldn't even be able to say there was rice grass there," says wetland ecologist Vishnu Prahalad. Native saltmarsh plants are recovering on their own, reclaiming ground lost decades ago.

The weed was first planted in the 1940s to beautify a local river. Instead, it colonized mudflats and saltmarsh, blocking access to feeding grounds and threatening to choke off water flow completely. Left unchecked, it would have destroyed the oyster farms that depend on healthy waters.

Duck Bay forms part of Tasmania's largest coastal wetlands, home to more shorebirds in summer than the rest of the state combined. Tiny red-necked stints fly here from Siberia and Alaska, traveling half a million kilometers over their 20-year lives, farther than the distance from Earth to the Moon.

Volunteers now scan the coastline attacking seedlings, while drones spray remaining patches with herbicide that targets the grass but spares native plants. Oyster farmer Jon Poke watched what invasive weeds did to other estuaries and knew his business wouldn't survive without protecting the environment.

The Ripple Effect

The wetland's recovery is breathing new life into the entire ecosystem. Yellow-eye mullet, caught both recreationally and commercially, have returned in huge numbers. One scientist remembers catching just two fish in the first year of monitoring, struggling to find any at all.

Now hardyheads, small baitfish that feed larger species, school through the recovering marshes. Native vegetation that seemed gone forever is spreading across former weed patches. Local farmers who initially worried about the financial cost now champion the effort.

Within two years, Landcare hopes to finish mass spraying and shift to monitoring. The wetland meets several criteria for recognition as internationally important under the Ramsar Convention, which would protect it for the thousands of shorebirds that cross the globe to feed here.

What started as a few volunteers attacking an overwhelming invasion has become proof that entire ecosystems can bounce back when communities refuse to give up.