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What's Up DoC - Whitebait - 27 August


Whitebait season is upon us, and while most of us Kiwis are familiar with the golden goodness of a whitebait patty, not many of us know that whitebait is made up of the juveniles of five native fish species.
 
What is whitebait?

Whitebait catch consists primarily of the young of three species of New Zealand's native freshwater fish. These are inanga (Galaxias maculatus), koaro (G. brevipinnis) and banded kokopu (G. fasciatus). Inanga is by far the most commonly caught species.

Giant kokopu (G. argenteus), short-jawed kokopu (G. postvectis) are also present in the whitebait run, and are two of New Zealand's threatened species of freshwater fish.

All whitebait species spend part of their life cycle in fresh water and part in the sea. Tiny fish hatch in late autumn and are carried along rivers out to sea where they live and grow over the winter.

In late winter and early spring, whitebait migrate back up rivers and streams, finally settling and growing in bush covered streams and swamps. The start of the migration is thought to be influenced by river flows (i.e. shortly after floods) and phases of the moon.

Mature inanga adults migrate downstream to lower river sections and estuaries to spawn in grasses covered by water during spring tides. The eggs remain in the grass until the next spring tide covers them again when the young hatch and are carried out to sea. The spawning habits of other whitebait species are not well known.

Can you tell the difference between the whitebait species?

It is pretty difficult, but a good whitebaiter can tell the 'goldenbait', which is the young of giant kokopu or banded kokopu. So strong is their instinct to migrate that they will climb the sides of the bucket in an effort to migrate upstream.

The banded kokopu or koaro are extreme athletes, and a vertical waterfall is no obstacle to them. In fact, last year a DOC ranger in Otago had to rescue some banded kokopu that had 'migrated' up the outer wall of a three story house and were residing in the roof guttering!

Record holders:

  • Giant kokopu: 58cm largest one 2.8kg - usually they reach 30-40cm
  • Short jaw: the largest ever was 37cm - named "Huryn" it lived out its days in the Hokitika aquarium.

New Zealand's really cool native freshwater fish:

Although most people think of trout or salmon when they think of freshwater fish in New Zealand, we actually have over thirty species of native freshwater fish. The galaxiids were named because early explorers to NZ thought that the scattering of white spots on their back looked like the Milky Way galaxy.

The five galaxiid species are found in many different habitats from lowland swamps to rocky streams. Their presence appears to be closely tied to overhead cover and waterside vegetation. Planting around streams helps keep the water temperature cool, and it also means that the fish have a place to shelter in.

Giant kokopu are probably our most spectacular looking native fish and they live in swampy and heavily vegetated streams, often in pools over a mud bottom. Short-jawed kokopu, banded kokopu and koaro prefer fast flowing rocky or boulder bottomed streams with forest cover. Inanga are less "fussy" but are generally found in lower catchment waters.

Whitebait conservation

Fifty years ago whitebait were so plentiful, people used to collect their catch in kerosene drums. These days the catch is a lot smaller.  Whitebait are managed by the Department of Conservation through the whitebait regulations, which determines the timing of the season and the types of nets that can be used. The point of the regulations is to allow some of the whitebait to make their wriggly way up the rivers and streams.

One way to protect the native fish, and to protect your whitebait catch for years to come is to only take what you need. 

One of the major problems affecting the whitebait fishery is the destruction of habitat for egg laying or adult fish. As whitebait adults tend to live in natural swamps and bush covered streams it is in the best interest of whitebaiters to ensure that adequate areas of these habitats remain.

Traditionally our native fish have preferred wetland areas, especially the giant kokopu, but with over 90% of wetlands being destroyed in 150 years, a lack of habitat is making life hard for these unusual and beautiful fish.

The Department of Conservation has been active in identifying whitebait spawning habitat and arranging for its protection. Protection has involved seeking the co-operation of landowners to have spawning areas fenced off from stock. The Department sees the protection of whitebait spawning habitat as playing a major role in enhancing the lasting viability of the fishery.

Another major problem is barriers that stop young fish from getting to adult habitat.

The threat of didymo:

In the South Island, didymo or rock snot is now a major threat. Please make sure that you CHECK, CLEAN and DRY all your gear to ensure that Didymo doesn't spread any further.
 
More info on whitebait species:

  • Inanga (Galaxias maculatus): The most common whitebait species grows into 9cm silvery cigar-shaped fish, preferring slow-moving coastal streams, swamps and lakes. Most live for a year, spawn in tidal riverside vegetation in autumn and die. Native to New Zealand, Australia, Chile and Argentina, inanga are among the most widely-distributed freshwater fish species in the world.
  • Koaro (Galaxias brevipinnis): Spectacular climbers, koaro use their large fins to scale steep slopes, even vertical waterfalls, into rocky, tumbling forest or tussock-lined streams. They grow to around 18cm, rarely up to 30cm, with a distinctive greenish-brown patterning, and spawn in late autumn at stream edges in high water flow. Nocturnal. The second most common whitebait species, koaro are also found in Southeast Australia.
  • Banded kokopu (Galaxias fasciatus): Adults may grow into 20cm fish with numerous pale stripes across the body. Good climbers as juveniles, adult "bandies", however, prefer small coastal streams with plenty of overhead forest cover. They spawn in heavy rains during flood flows in streamside forest litter and gravels. Mainly nocturnal. Threatened. Endemic.
  • Short-jaw kokopu (Galaxias postvectis): A drab, brownish fish as adults which may grow to 20cm, rarely to 30cm or more. Like koaro, they climb streams inland. They are restricted to streams, large or small, with native forest cover. Similar spawning habits to banded kokopu. Nocturnal. Threatened and sparsely distributed. Endemic.
  • Giant kokopu (Galaxias argenteus): aka Maori trout. Adults are olive-green, blunt-nosed heavy-set fish, up to 50cm long. Their golden hieroglyphic markings, reminiscent of the Milky Way galaxy, have given the genus, Galaxias, its name. Giant kokopu prefer overgrown gently flowing streams, swampy lagoons and lake edges near the sea. Mainly nocturnal. Threatened and in gradual decline. Endemic.

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