Whitebait is a term used to collectively describe the juvenile form of a number of small native fish species that are edible. They are usually 25–50 mm long and often travel together in schools along coasts, in estuaries and up rivers. Whitebaiting is the activity of catching whitebait. This is usually done in rivers with fine meshed fishing nets. Historically, scoop nets were used. People eat the entire fish including the head, fins and gut.

Galaxiids

In New Zealand, the term whitebait includes the juvenile form of five species of the fish family Galaxiidae or galaxiids:

  • ĪnangaGalaxias maculatus
  • Kōaro (Galaxias brevipinnis
  • Giant kōkopuGalaxias argenteus
  • Shortjaw kōkopu (Galaxias postvectis
  • Banded kōkopu (Galaxias fasciatus

Galaxiids are mostly small freshwater fish found in the southern hemisphere. The adults mainly live in rivers and streams and often prefer native forest surrounds. The galaxiids lay their eggs in freshwater, and after hatching, the larvae are swept down to the ocean where they grow. The young then move back up into freshwater in large shoals known as runs. Whitebaiters set nets along the river’s edge hoping to catch this delicacy. Whitebait commands high prices – it is the most costly fish on the market and is known to whitebaiters as white gold

The īnanga life cycle

The most common species of whitebait is īnanga – also known as the common galaxias or matamata to the people of Waikato-Tainui. The life cycle of the īnanga is the best understood of the five species of whitebait.

  • Eggs: The eggs are laid during spring tides (higher than average tides) in autumn on the banks of the river in vegetation flooded by the tide, near estuaries.
  • Larvae: The next spring tide causes the eggs to hatch into larvae, which are flushed out to sea.
  • Juveniles (whitebait): After about 6 months at sea – floating as part of the ocean’s plankton mass – they return to the rivers and move upstream to live in freshwater, and they grow into adults.
  • Adults: The adults swim back down the river to spawn in or near the estuaries. When spawning takes place, the water appears to boil with the numbers and activity of the fish.

The adults are about twice the size of the juveniles. Īnanga usually live for about a year.

Catching whitebait

Whitebaiting is a seasonal activity with a limited time period. It occurs when the whitebait are migrating upstream in spring. There are strict controls about net size and rules against blocking the river to channel whitebait into nets. This is to ensure sufficient numbers of whitebait are maintained – they are able to pass through to become adults to spawn the next generation.

Whitebait are sensitive to objects in the river and are good at dodging nets. Whitebaiting therefore requires some skill. Nets are generally small, open-mouthed and hand-held (slightly bigger set nets may be used where whitebait are more plentiful). Nets on a long pole (scoop nets) have to be attended by the whitebaiters so they can lift the catch out as soon as it enters the net. Otherwise, the whitebait quickly swim out again.

Other species are sometimes caught in whitebait nets such as smelt (Retropinna retropinna). These are often referred to as ‘number 2 whitebait’. Juvenile bullies (whalefeed) and glass eels (juveniles of longfin and shortfin eels) also get caught as they migrate upstream.

Threats

Whitebait runs are smaller than they used to be due to a range of factors. The main problem is a decline in the quantity and quality of habitat. This is caused by barriers for fish migrating into tributaries and lakes (such as floodgates, culverts and weirs), draining of wetlands and other changes in land use. Degradation and loss of their spawning grounds is also a problem. Livestock trampling and lack of shade over riparian (streamside) spawning areas kills whitebait eggs. Declining water quality associated with land use change and intensification has also probably affected whitebait numbers.

It is interesting to note that the largest whitebait runs occur in South Westland – where there have been fewer changes in land use and there has been no decline in water quality.

Nature of science

Investigations in science often lead scientists to understand associated problems. For example, scientists studying whitebait realise that culverts in streams and rivers hinder whitebait from their migrating behaviour. Scientists are now designing structures to put on and into culverts to help whitebait negotiate these obstacles.

Useful links

    Published 19 March 2014