top of page
Wester Mosquitofish  Gambusia affinis
Introduced. Not assessed.

A native to North America, this species has been introduced to many parts of the world in the belief that it helps eliminate mosquito larvae and thus helps prevent the spread of malaria. While mosquito larvae form part of their diet, they also consumed other small aquatic invertebrates which are eaten by native populations thus being detrimental to native species.

Introduced to Aotearoa New Zealand around 1933 to several ponds in the Auckland area. It soon spread via several methods and is now widespread through the North Island and several areas in the north of the South Island. They have shown up in eDNA samples in local streams.

Apart from being widespread, they are an aggressive species and out-compete Galaxiids and Bully's for available food supplies.

Females can be twice the size of males, reaching 6-7 cms and give birth to live young.

Western Mosquitofish - Wikipedia
Goldfish  Carassius auratus
Introduce. Not assessed

Goldfish are a popular pet throughout the world, often kept in cramped conditions. Because they are a freshwater species and can tolerate a degree of coldness, they are often released in outdoor ponds and it is from these deliberately release fish that they have spread and are now classed as a pest species, including in Aotearoa New Zealand.

Wild goldfish can grow to between 12-22 cm. A member of the carp family it has been bred for many years and is now considered .domesticated.

Adults lay eggs which are sticky and adhere to vegetation, hatching within 72 hours. Fry are numerous and may be eaten if adults are present. Normal diet consists of aquatic crustaceans, insects and some plant matter
South African Preying Mantis  Miomantis caffra
Introduced. Not assessed.

This species was first recorded around 1978 around the Auckland area. Over time it has spread further south, including some areas of the north South Island. Because of its aggressive nature, it is now the prominant species, displacing Aotearoa New Zealands endemic species Orthodera novaezealandiae in many areas.

The South African is the larger of the two species with males of the native being attracted females of the invader and because they can be cannabalistic, it reduces breeding potential.

Oetheca (egg cases) range from 12-20mm long and are soft creamy brown when first laid before hardening. Nymphs hatch over a period of time and vary in colour from  brown to green.

Although not considered a pest at the moment it has the potential. The species are easy to distinguish with the native having a blue/purple patch on the inside of the leg. Sexes of both differ with male being spaller than males. 
 
European Hedgehog  Erinaceus europaeus
Introduced. Not assessed.

People have mixed emotions about this prickly wee beastie - on one hand it is a familiar animal and has been for generations through children's literature and is an extremely efficient consumer of snails and slugs.

Since its introduction in the 1870's in an attempt control introduced crop pests it has had a dramatic effect on Aotearoa New Zealand's endemic invertebrates. also taking birds eggs.

In the UK the species is in serious decline with populations down as much as 70% in some area, especially where badgers are present. It is far removed from the population here with fairly high densities in many areas, including in farmland around Foxton. Many are trapped.
Freshwater Gold Clam Corbicula fluminea
Introduced. Not assessed

The natural distribution of this small molluscs is Southeast Asia but has now been introduced and is now widespread in North America and many parts of Europe. In Aotearoa New Zealand was initially found in the Waikato when and now rather worryingly, in a man made lake.

This small clam measures only 2cm when fully grown and because of its fast rate of reproduction can colonise new areas rapidly, with the increase in numbers potentially creating problems with outlet pipes and drains.
 
It is an easy species to identify because of the deep ribbing on the shell and the rather elongated shell distinguishes it from several native species. Because of its filter-feeding on watercourse bottoms, it can accumulate toxins and consumption is not recommended.








https://www.mpi.govt.nz/dmsdocument/56950/direct
Boneseed Chrysanthemoides monilifera
Introduced. Not assessed.

This South African species is a common pest of coastal regions being found in sand dunes, cliffs, water margins and roadsides and is viable in different soil types and can withstand both salt and wind.

Once established this rampant weed can form dense strands which can reach 2-3 metres in height. It is estimated that one large bush can produce around 50000 seeds each year that can spread by a number of means - birds, possums, stock and when areas flood, they can be transported many kilometres. Seeds can germinate after even after fire.

Removal of plants, either by digging mature plants or pulling seedlings by hand will help but checks needed for new seedlings that appear.
Gorse  Ulex europaeus
Introduced. Not assessed

This spikey plant is native to Western Europe and its bright yellow flowers can be seen throughout the year, peaking in the spring to Autumn months.

Widely used as a hedging to contain stock, it produces an abundance of seeds enabling a rapid spread to the point of it becoming an invasive species in most countries it has been introduce to, including Aotearoa New Zealand.

It is a very resilient species being able to survive burning and spraying if not followed up. New shoots will appear on stems and will colonise cleared areas of forest. However, can be used as a nursery for natives species, protecting new growth and it will eventually die when trees mature and cast shade over the gorse.
Manawa/Mangrove  Avicennia marina australasica
Native. Not threatened

Restricted to northern areas of the North Island in Aotearoa New Zealand and Eastern Australian states Queensland, New South Wales and Victoria. Also occurs on  Lord Howe Island.

While in its natural setting it is extremely valuable as a fish nursery, it is reputed to have been introduced into other areas where it has the potential to establish where it could impact other species.

The chief habitat is coastal, especially estuaries and tidal channels which have a high accumulation of silt and mud and can rapidly spread under these conditiond.

Flowers between February and April and the yellow/orange flowers can take six months to develope into a ripe seed. These float and this is another way they can disperse over long distances, even to the estuary where sprouting seeds have been discovered..


 
Spartina Sporobolus anglicus, Sporobolus alterniflorus
Introduced. Not assessed

Commonly known as Cord Grass, this fast growing species is a very persistent pest in some area and is one of the few species that will grow in the soft mud of estuaries.

It was widespread in the estuary here at Foxton Beach and a serious effort was started in the late 1980's to control it which continues to this day.. Continued spraying has reduced it now to such an extent that a dog is now required to locate the few remaining clumps, Wink a conservation dog does am excellent job and it a joy to watch.

It is reputed to be sterile but spreads by rhizones which creep through the substrate and by fragment which can survive long spells in salt water.
Feral Pigeon  Columba livia "domestica"
Introduce. Not assessed

This species is, in some literature, still called the Rock Dove but they are not true and have been been domesticated over many years. True Rock Doves are found in Western Europe, North Africa extending to South-east Asia. All seen here are this domestic type.

They are abundant in some areas and although not really classed as a pest they can be carriers of a number of diseases which effect both humans. E. coli is a zoonotic (can pass to humans) disease and is tested for in most water samples. Large numbers of pigeons roost under bridges over waterways!

Pigeons are prolific breeders with some young being reared at most times of the year. Nests can be flimsy structures, usually on a ledge. Two whitish eggs are laid which hatch after around 16 days of incubation. Initially the squabs (chicks) are fed on crop milk which is the lining of the crop before being regurgitated solid food.
Spiders
Pig, Deer, cats. rabbit
Inkweed  Phytolacca octandra
Introduced. Not assessed.

Whether in flower or setting seed this plant is easily identifiable by its erect clusters of flowers which set to form greenish berries, later turning purple-black. 

It is native to tropical South and Central America but was introduced to Aotearoa New Zealand as a garden plant and became  naturalised in around 1867 and established here through the dumping of garden waste.

Grows to a height of around 2 metres, growing quickly it can form dense patches, aided by its ability to tolerate a wide range temperatures , fire damage, wind and ground disturbance. It has a long flowering season from November through to August and sets seed once flowering has finished.




 
Giant Reed  Phragmites karka
Introduced. Not assessed

The first confirmed occurrence in Aotearoa New Zealand was in 2006
but because of the size of infestation is likely to have been present for a number of years. The Manawatū is a stronghold for this plant and was first discovered in Tangimoana. Since then it has been recorded  from over 160 sites throughout the country.

The primary habitat is esturine and water courses where its rhizones push through the soft mud, although substrate does not seem to be a barrier as been known to push up through tar-seal.

Very dense clumps can be formed and one sampled contained 644 individual stems in one square metre. Control of this noxious weed is problematical because it is resistant to all current sprays and other methods have had limited success. This, in the near future, is likely to be one of our major pest species.
Mice
Brown Mudfish  Neochanna apoda
Endemic. At risk declining.

Five species of mudfish, all endemic are found in Aotearoa New Zealand. Of these five, the Brown  is the local species and although there seems to be only one record for the estuary, it is present in small numbers in the loop at Foxton.

It is a member of the Galaxiid family which contains many of our native freshwater species, including those that make up the Whitebait catch but unlike them they are not migratory

These are fascinating fish with a fairly unique lifestyle. They are found in damp habitats such as swamps. wetlands and slow-flowing streams and when these dry out and surface water disappears they are able to survive by searching out damp vegetation or tree roots where they are able to remain moist
bottom of page