Biological Values of the TEER

The Tamar estuary and Esk Rivers play an important role in supporting the biodiversity of northern Tasmania.

Eastern Gambusia (Gambusia holbrooki)
The Eastern Gambusia (Gambusia holbrooki) is a threat to native ecosystems. Photo credit Neil Armstrong.

Gambusia Management

Gambusia prey on the eggs and young of native frogs and fish in the kanamaluka/Tamar estuary and compete for food and shelter with native species. Left unchecked, the impact of Gambusia in Tasmania would be magnified, particularly in the absence of substantial community awareness.

The aim of this project is to control or eradicate the pest fish Gambusia in Tasmania, The methods employed to date include research into trap development, direct control actions and raising awareness within the community. Trapping and hand netting in open/interconnected waterways is the major component of the control actions, with temporary drying of drainage lines and if necessary, poisoning being used in isolated water bodies. Raising awareness promotes community involvement and minimises the risk of people spreading Gambusia beyond the Tamar Valley. Maintaining or building volunteer participation in the trapping program is a core focus of the project.

Gambusia education will be shared with the community through: NRM North events; agricultural shows; QVMAG Big Day of Science; Community children's education events; and World Rivers Day at the Tamar Island Wetland Centre.

To avoid infecting other areas, thoroughly check all boating and fishing equipment for Gambusia before relocating.

Please report all sightings of Gambusia to the Inland Fisheries Service (IFS) on

(03) 6165 3808 or

Fines of up to $25,000 apply to people found moving or possessing Gambusia.

Green and Golden Frog (Litoria raniformis)
Tadpoles of the vulnerable-listed Green and Gold Frog (Litoria raniformis) are particularly affected by Gambusia.
sea lavender_limonium austral
The number of plants of sea lavender have increased along the Tamar estuary.

Saltmarsh Surveys

In 2013, coastal saltmarsh was recognised as a nationally-threatened vegetation community under the federal Environmental Protection and Biodiversity Conservation Act  (1999).  Northern Tasmania boasts significant areas of coastal saltmarsh, often associated with estuaries and coastal wetlands and ranging in size from less than 1 hectare to over 60 hectares. Although important for stimulating the productivity of estuaries and wetlands through nutrient cycling, and being better at sequestering carbon than equivalent forested areas, saltmarshes are often overlooked for their value and contribution to commercial, recreational and biodiversity outcomes. NRM North's annual Saltmarsh Survey aims to collect data on the biodiversity and threats of northern Tasmanian saltmarshes, in order to inform their future management.

NRM North coordinates saltmarsh surveys at several locations across northern Tasmania and individuals and community groups are welcome to be involved. These surveys are part of an ongoing project to map and monitor Tasmanian saltmarsh habitats and their bird and plant inhabitants. No expertise is required and all training and survey materials are provided. Please contact us if you'd like to find out more.

Common Invertebrates

Waterbugs are often referred to as macroinvertebrates and microinvertebrates. Macroinvertebrates are used globally as an indicator of water quality in fresh waters. Microinvertebrates are small waterbugs usually only seen using a microscope.

Macroinvertebrates were collected from 2017 to 2019 at 6 sites in the mid–upper and upper zones of the kanamaluka/Tamar estuary. The number of individuals (abundance) found at each site ranged from 11 to 185, and the number of different types (richness) ranged from 3 to 32. In total, 32 different types of macroinvertebrates were found from Swan Point to the Yacht Club Basin (identified to order, family, genus or species).

Decapoda Hymenosomatidae Amarinus can be found along the length of the kanamaluka/Tamar estuary. Photo credit Shane Westley.

Quick Q&A

What should I do if I find Gambusia on my property?

If you find Gambusia on your property, please report it to the Inland Fisheries Service by emailing or phone (03) 6165 3808.

How do I best remove gambusia from boating and fishing equipment, to minimise the spread?

The best way to ensure clean boating and fishing equipment is to follow the Check, Clean and Dry method:

Check your gear and remove any algae, weeds and seeds.

Clean your gear.

  • Scrub in a 2% solution of household bleach (200 ml bleach mixed with water makes 10 litres) or a 5% (50 ml per litre) salt, nappy or antiseptic cleaner or dishwashing detergent solution.
  • Soak in the solution for a minimum of one minute.
  • For even better results, use a hot water solution and soak for 30 minutes.
  • For items that are difficult to clean and dry, soak for 45 minutes in water kept at 45 degrees or higher in a solution of 5% (50 ml per litre) household bleach, dishwashing liquid or nappy cleaner.

Dry your gear completely and wait an additional 48 hours.

  • Some materials may need much longer, even several weeks to dry.
  • Using hot air is a faster alternative when available.
What is being done to control the spread of gambusia in Tasmania?

Annual surveys are conducted by IFS and weekly monitoring is conducted by volunteers at Tamar Island Wetlands.

NRM North funds and coordinates a Gambusia Education and Awareness Program that aims to raise awareness of gambusia within the community.

Lastly, the Trojan Project (a collaboration between the University of Tasmania, Inland Fisheries Service, NRM North, and the University of Adelaide and is funded by the Australian Research Council) is focused on developing a genetic control strategy. For more information contact Dr Jawahar Patil, (03) 6226 8318.

Water Program & Projects

Water Program

Return to the Water Program.

Ecosystem health of the Tamar

Data collected under the Ecosystem Health Assessment Program is used to produce the Tamar Estuary Report Card.

Monitoring water quality in the TEER

Learn more about the Water Quality Improvement Plan.

Working together to manage the TEER

Learn how we are working together for healthy waterways.