New Zealand streams don’t have native fish! Or do they?
People often tell me that they have never seen fish in their local stream, however, it’s surprising the number of streams, including urban ones, that have good populations of native fish. In this article, we reveal the native fish that we’ve found in some of the urban streams around the Wellington Region.
One of the main reasons why people may not have seen any fish in their local stream is that most native fish species are nocturnal, which means they are most active after it is fully dark. Another reason is that during the day, species like the longfin and shortfin eel spend their time hiding under overhanging vegetation and undercut stream banks. A lot of our native fish species are also very well hidden and blend into the colours of the streambed, so in some cases you really do have to keep your eyes peeled for any movement.
The Cardno Ecology team is regularly asked to undertake fish surveys and occasionally rescue fish from stream sections where instream works are required. A great number of fish detection work has taken place in and around Paraparaumu with the map showing the locations where we have found one or more species of fish. As you can see, many of the areas that have been fished are urban streams. The table below gives an indication of the number of fish and the average size of the fish that we’ve found in the Paraparaumu area during the last few years.
|Common Name||Maori Name||Scientific Name||National Threat Status||Number Found||Average Size (cm)|
|Shortfin eel||Tuna||Anguilla australis||Not Threatened||1488||37.6|
|Longfin eel||Tuna||Anguilla dieffenbachii||At Risk-Declining||118||45.8|
|Introduced and Naturalised||2||4.0|
|Koaro||Koaro||Galaxias brevipinnis||At Risk-Declining||1||4.0|
|Banded kokopu||Kokpou||Galaxias fasciatus||Not Threatened||24||5.8|
|Inanga||Inanga||Galaxias maculatus||At Risk-Declining||1800||5.8|
|Upland bully||Gobiomorphus breviceps||Not Threatened||7||4.7|
|Common bully||Toitoi||Gobiomorphus cotidianus||Not Threatened||488||3.9|
|Giant bully||Tipokopoko||Gobiomorphus gobioides||At Risk-Naturally Uncommon||12||8.8|
|Redfin bully||Gobiomorphus huttoni||Not Threatened||4||5.8|
|Freshwater crayfish||Koura||Paranephrops planifrons||Not Threatened||11||4.5|
Some of our best fishy finds have been...
Longfin eel (Anguilla dieffenbachia)
The mighty long-fin eel only breeds once, at the end of their lifespan. When they are ready to breed, they migrate out to sea to a location which is currently unknown by scientists but is thought to be near Tonga. The young eels then somehow make their way back to New Zealand with the help of ocean currents. Once they reach freshwater, they transform into glass eels (almost like small transparent adult eels) and live in estuaries for about a year, during this time they acquire their colouration which is similar to adults. From here, these small adults, known as elvers, migrate upstream to suitable habitat and can live on average for 23 years for males and up to more than 60 years for females.
Shortjaw kōkopu (Galaxias postvectis)
Shortjaw kōkopu are in short supply and are ranked as Threatened-Nationally Vulnerable. Therefore, it is always a treat to see this species when we are out on site. Shortjaw kōkopu are amphidromous, which means their fry (newly hatched fish) go to sea, later returning as juvenile fish to freshwater where they grow to adulthood of about 350mm in length.
Giant kōkopu (Galaxias argenteus)
Giant kōkopu are New Zealand’s native “trout” and are considered to be At Risk-Declining. They grow to about 400mm in length and have this beautiful speckling. Giant kōkopu are also amphidromous, with larvae going to sea soon after hatching and returning about four months later as small juveniles. Juvenile giant kōkopu form a small part of the annual whitebait catch.
Banded kōkopu (Galaxias fasciatus)
Banded kōkopu are amazing climbers and can turn up in all sorts of places. We’ve heard reports of them living in the stormwater pipes beneath Rimutaka prison and under roads in the Wellington CBD. Four banded kōkopu were even found living in a very small pool of water that was 1m long, 400mm wide and 400mm deep with only intermittent connection to a flowing stream and upstream of a 500m length of “stormwater” pipe in Porirua. The banded kōkopu are also amphidromous and the juvenile fish manage to climb back up to such isolated pockets using their pectoral fins.
Kōaro (Galaxias brevipinnis)
Like banded kōkopu, kōaro are excellent climbers allowing them to reach further upstream habitats than other members of the whitebait family. Kōaro are also a member of the Galaxias genus which, as the name implies, when looked at with a spotlight show a speckled pattern much like a galaxy.
Giant bully (Gobiomorphus gobioides)
Male giant bullies vigorously defend a territory in which the female bully can deposit many thousands of eggs. The male guards the eggs for several weeks until they hatch when it is then thought that the newly hatched bullies go to sea and return after several months. These are the largest of the bully species and can grow to about 240mm in length.
Freshwater crayfish (Paranephrops planifrons and Paranephrops zealandicus)
New Zealand has species of freshwater crayfish that can grow to 70mm in length. These are largely found in areas of permanently flowing water, but our ecologists have also found them in intermittent flowing streams with large amounts of macrophyte growth.
If you would like us to undertake a fish survey, rescue fish from a stream or pond, or conduct a fish passage assessment, please contact Claire Bullock.