Currently there are a wide range of pest plants and animals threatening our region. There are also some very invasive pests, that will have a devastating effect if allowed to establish. Some examples include;  catfish, wallabies, Asian Paddle Crab, Mediterranean fanworm and hornwort aquatic weed. 

We have developed the Regional Pest Management Plan (RPMP) as a tool to actively manage pests throughout the region. The Plan’s aims are to prevent new pests from becoming established in the region and to minimise the impact of those invasive pests that are already here.

Controlling pests in the Bay of Plenty region is a huge job and we need everyone to help with pest control. Successful pest control starts with awareness, motivation, the correct information being readily available, and the right people to help you. We have a Biosecurity Team that educates, manages and assists in the control of plant and animal pests.

Top pest threats in our region

Catfish are an unwanted pest threatening to ruin the renowned Rotorua Lakes and tributaries. 

They feed on small native fish, trout and their eggs. Catfish also compete for food with other native species, including koura (freshwater crayfish). In high numbers, catfish can degrade water quality when they stir up sediments to feed, making water murky and unpleasant for lake users and wildlife.

A live, 26 centimetre long brown bullhead catfish (Ameiurus nebulosus) was caught at Te Weta Bay, Lake Rotoiti on 16 March 2016.

Catfish are a pest species that has become widespread in Waikato waterways including Lake Taupō. This is the first time a live fish has been found in the Bay of Plenty.

With the help of our partners (Te Arawa Lakes Trust, Department of Conservation, Fish and Game, the University of Waikato, NIWA and Rotorua Lakes Council) and the local community we are determined to stop the spread of catfish.

You can help prevent aquatic pests like catfish from being spread in the Bay of Plenty by checking and cleaning all boating and other watersports equipment before using it in a different waterway, every time. If you see a catfish in any Bay of Plenty waterway, please report it by calling us on 0800 STOP PESTS (0800 786 773).

The Bay of Plenty Regional Council conducts regular surveillance of vessels and marinas to stop fanworm from establishing in our region. Mediterranean fanworm is known to be present in the Hauraki Gulf of Auckland, Lyttleton and Whangarei harbours. It was discovered on two barges in Coromandel Harbour last year, a vessel in Waikawa Bay earlier this year, and is the subject of an elimination programme currently underway in Nelson Marina.

What does it look like?

Mediterranean fanworm has a brownish/grey tube up to 40 centimetres long. At the top of this tube is a single white fan, banded with pale orange or brown. It often grows in clumps, although the specimen recently found was growing alone.

The Mediterranean fanworm does look like some native New Zealand fanworms, but it is larger and it has only the single fan. If it has two spiral fans, it is not this pest.

Why is it a problem?

Mediterranean fanworm can grow in dense, thick mats that compete with native plants and animals for nutrients and space. It can interfere with boat equipment and aquaculture, and affect recreational activities like diving by changing the underwater character. Once well established, it is very hard, or even impossible, to eradicate.

What can I do to stop it spreading?

Boat owners should keep their boat hull clean and anti-fouling paint fresh. 

Take extra care to check your hull before you move your boat from one area to another. It's important to contain and dispose of any fouling you clean off your boat carefully - allowing it to sink to the sea bottom or drift away may aid the spread of marine pests.

What should I do if I see one?

For suspected finds anywhere in New Zealand (apart from Lyttelton and the Waitemata) please call MPI on 0800 80 99 66.

If you are the owner/operator of a boat, you can help prevent the spread of this marine pest by keeping your anti-fouling paint in good order and ensuring your boat hull, trailer and fishing gear is thoroughly cleaned before taking your boat to a new area.

Read more about the Mediterranean fanworm on the Ministry for Primary Industries website.

Hornwort weed is a submerged pest plant that forms dense beds and shades out native species, preventing them from establishing. It can also contribute to blockages of waterways and flooding. Rotting vegetation stagnates water, killing fauna and flora.

Hornwort weed poses a significant threat to our lakes and to prevent the spread, lake users should always remove any traces of weeds from their boat, trailer and gear as even the smallest fragment could create a new colony.

A swimming crab that is native to South East Asia and now present in Auckland and Northland.

They live in estuaries where there’s firm or fine muddy sand. They’re extremely aggressive and have the potential to compete with native crabs for space and food. They also prey on native species such as shellfish, fish and other crustaceans.  Adult shells grow up to 12 centimetres wide and due to their rapid growth and reproduction rates they can establish quickly.

This invasive pest is well established in the Hauraki Gulf and Northland, and in January 2018 was discovered for the first time in the Bay of Plenty during a summer marine pest survey conducted by MPI (Ministry Primary Industry).

A mature male and female pair were caught in the same pot near the Matapihi bridge in Tauranga harbour however ongoing surveillance by Council and the University of Waikato has found no other crabs.  

Although small in size Dama wallabies have the potential to become a big problem. This is why the Bay of Plenty Regional Council, Department of Conservation and Waikato Regional Council are working together to stop them from spreading outside of Rotorua. 

It's hard to believe such a cute, shy animal could be a problem but they have a huge appetite for grass, seedlings and shrubs. They're nocturnal and cautious so they're very hard to find and catch. If allowed to spread, wallabies could become as big a problem as possums impacting our economy and environment not just regionally but nationally.

If you see a wallaby sighting report by ringing 0800 STOP PESTS (0800 796 773).

Case studies

At the start of the new millennium, rats were so abundant at Lake Tarawera they ran freely through properties at all hours of the day and night and the native bird populations were suffering.

Residents initiated the Lake Tarawera Rat Control Programme with support and funding from locals, Council and the Department of Conservation. The programme is focused on restoring native birdlife by controlling rodents on 471 properties and two high value ecological sites.

More than a decade of rodent control has led to a greater abundance and diversity of bird life at Lake Tarawera. Independent contractors have carried out two bird counts - the first in 2005 and another in 2008. In 2005, only 16 different bird species were observed and a total of 472 birds were counted. By 2008, 897 birds were counted from 29 different species. Half of those counted in 2008 were native species, and tui, kereru, grey warbler and shining cuckoo numbers showed the greatest increase.

The programme continues today through volunteer effort and innovation. Funding for bait is supplied through our Biodiversity Management Programme and landowners purchase the bait stations for use on their properties.

The 10-year collaboration between Council and New Zealand Kiwifruit Growers Inc. (NZKGI) has led to a significant reduction in wild kiwifruit in the Bay of Plenty. With the emergence in the region of kiwifruit vine disease Psa (Pseudomonas syringae pv. Actinidiae) control of wild kiwifruit that may host the disease is even more important.

Council identifies wild kiwifruit populations and monitors control work, while NZKGI contributes funding from its members towards this work.

Wild kiwifruit is listed as a ‘Containment Pest’ in the Regional Pest Management Plan, which means landowners responsible for the pest, are also responsible for its control.  

Wild kiwifruit is spread predominantly by birds, rats and possums that have eaten waste fruit and transported many tiny seeds in their droppings, often across many kilometres. If left uncontrolled, wild kiwifruit forms a mound of tangled stems that can grow up and over trees, smothering and killing them. Without active control, areas of native bush would eventually disappear under a blanket of kiwifruit.

The great news is that some 25,000 wild kiwifruit vines have been destroyed in the Bay of Plenty. Large wild vines have been almost entirely eliminated and the number of smaller vines is declining every year.

Council also supports the Waste to Gold initiative led by Scion Research, Zespri International Ltd and NZKGI, which converts waste kiwifruit into bio-plastic, helping reduce the 50,000 tonnes of waste kiwifruit otherwise left in the environment.

Wallabies are a ‘Containment’ pest animal in the Regional Pest Management Plan and are carefully monitored under the Regional Pest Surveillance Programme. The wallabies’ penchant for native tree seedlings, ferns and grasses means they graze the forest floor, preventing natural regeneration.

Council’s goal is to contain and manage wallaby populations within their established range around Rotorua, and stop their spread to new areas.

Despite increasing property development in Tauranga’s Welcome Bay area, a small population of wallabies remained unnoticed for nearly 10 years at Rocky Cutting Road. The elusive population was confirmed after a sharp-eyed Council staff member spotted a newspaper article that mentioned a dog chasing wallabies in the Welcome Bay area.

A Council survey of local residents found that several had seen wallabies from as far back at the 1990s. Motion-sensing infrared cameras were installed in bush remnants on private land to help gather information about the extent of the wallaby population and, at the same time, record their interest in a range of baits.

Feratox® strikers (encapsulated cyanide bait) were used at one of the Welcome Bay properties, killing 16 wallabies and 77 possums. On-going monitoring will assess the number of wallabies remaining within the control area and on the surrounding properties.

Monitoring and control methods for wallabies are still under development and, with lifestyle properties immediately next to the bush areas where the wallabies live, the community will be engaged in planning and decision-making. Control methods will be carefully chosen.

In late 2010, Councils in the Bay of Plenty joined forces to provide urgent assistance to MAF Biosecurity NZ (now part of the Ministry of Primary Industries, or MPI) and ZESPRI International, in response to the outbreak of the kiwifruit bacterial disease, Psa (Pseudomonas syringae pv actinidiae).

The PSA outbreak was completely unexpected and required speedy and professional work from all organisations. Bay of Plenty Regional, Tauranga City and Western Bay of Plenty District Councils helped distribute messages to the community and provided operational support to MAF. This included collecting plant samples from orchards, identifying and managing sites for collection and incineration of infected vines and managing the environmental impacts of these operations.

Despite the intensive efforts of these organisations and the kiwifruit industry, Psa became well established and destroyed many of the kiwifruit cultivars grown in the Bay of Plenty.

Longer-term management of Psa is now done by Kiwifruit Vine Health (KVH), which is governed by a board of directors who represent kiwifruit industry groups, post-harvest operators and the MPI. We provide advice or assistance to KVH on an as-required basis. For example, Council monitors the impact of the limited approval spray treatment, streptomycin (KeyStrepto), on air quality.

Good spotting by Waihau Bay (near Te Kaha) cropping contractor Joe Rua back in 2006 helped stop the spread of one of the real nasties of the weed world – horsenettle. It’s toxic, thorny, hardy and incredibly invasive – and it probably piggybacked a trip to New Zealand from the United States in contaminated maize seed.

Due to the unpleasant characteristics of horsenettle, it is listed as an ‘Eradication Pest’ in the Regional Pest Management Plan, which means that the Regional Council is responsible for the weed’s control and control costs.

Horsenettle is incredibly hard to kill due to its underground rhizomes, which can sprout hundreds of new plants even when it appears to be dead above ground. Cultivation can aid the spread of the surviving rhizomes. Control work has been slow and painstaking and, despite not being required to help, contractor Joe and the landowners have been incredibly supportive, assisting council staff.

Many hours have been spent walking up and down the maize rows seeking out and destroying horsenettle plants, repeated several times each year. One area of the farm, covering 1.5 hectares, is too densely infested for the ‘seek and destroy’ method of control. Instead, the landowners have left the paddock fallow and contractor Joe regularly boom sprays the area.

Council staff, Joe and the landowners are happy with the progress, albeit very slow, towards eradicating horsenettle at Waihau Bay and all are appreciative of the collaborative approach.

Latest management tips

Improve your pest management practices with the latest research. If you find anything new, we can share it here. 

New glyphosate gel

The new glyphosate gel product is useful for treating individual problem weeds and the cut stumps of trees and shrubs that are likely to re-sprout. It’s a very convenient method of dealing with minor weed problems as you don’t have to mix up large quantities of spray when you only need a little bit. There are several brands and they are available from most garden centres and hardware stores. 

New herbicide for pasture weeds

Tordon Gold was, for a long time, a popular herbicide for many pasture weeds. Some years ago this was taken off the market and replaced with Tordon Max, later shortened to TMax. While still available and providing excellent control of pasture weeds and, importantly, woolly nightshade, this has recently been reformulated under the name PastureBoss. It has the advantage of being much cheaper than TMax. When using either, make sure you read the label very carefully.

How to kill trees and shrubs that re-sprout when cut down

This technique applies to many plants such as privet, woolly nightshade, barberry, and willows that send up shoots from the stump and re-grow after being cut.

Mix this strong brew: 1 part glyphosate (such as Roundup) and 4 parts water (1 cup glyphosate to 4 cups water).

Cut the plant down as close as possible to ground level. Within half an hour, spray the stump liberally over the cut surface and the sides of the stump to ground level and any roots showing above ground with the above mixture. For small numbers of stumps, a small trigger bottle (as used for household cleaners) will do, or for large quantities, use a knapsack, which you may only need to partially fill. 

Automated pest control

Automated pest animal traps that re-set themselves can save time and effort in the field. There are two main types:

  • Kill trap - kills the animal by delivering a fatal impact (such as the Goodnature A12 possum trap, and the A24 rat and stoat trap, which the Department of Conservation is currently field testing).
  • Bait station - delivers a lethal dose of toxin (such as the Spitfire stoat and possum bait stations, which are still under development). This device fires a targeted lethal dose of toxin into the animal when the trigger system is tripped. 

Paw recognition

Paw recognition software is under development and could provide accurate species abundance data. Initial results indicate that the software may be sensitive enough to identify individuals within the same species. 

This software could be very useful in the protection of non-target species. For example, bait stations or kill traps could be set to trigger only for the targeted pest species.