What are whitebait?
The word whitebait does not refer to a single species. It is a general term used in many countries to describe small freshwater fish that are tender and edible. In New Zealand it describes the juvenile forms (around 4–5 centimetres long) of five species of the fish family Galaxiidae, plus common smelt.
In spring, whitebait make their way upstream from the sea, swimming near the river’s edge. Large shoals are referred to as runs. Big runs often follow floods, a few days after the water clears – usually in the daytime on a rising tide.
Whitebait can be caught at the mouths of many New Zealand rivers. Whitebaiters set nets and sit on the river bank, hoping to harvest this popular delicacy.
Whitebait are the juveniles of six species:
- īnanga (Galaxias maculatus)
- kōaro (Galaxias brevipinnis)
- banded kōkopu (Galaxias fasciatus)
- giant kōkopu (Galaxias argenteus)
- shortjaw kōkopu (Galaxias postvectis)
- common smelt (Retropinna retropinna)
As adults the species differ in size, markings and habitat.
Īnanga and giant kōkopu prefer lowland marshes and sluggish waters. Kōaro, banded kōkopu and shortjaw kōkopu are found in forest streams at higher altitudes.
Īnanga adults are barely twice the size of juveniles. The other species grow much larger – the giant kōkopu can reach half a metre in length.
In many rivers īnanga, kōaro and banded kōkopu make up most of the whitebait catch, with īnanga being the most common species.
Common smelt is found throughout the country but it sometimes referred to as ‘second-class whitebait’. Whitebaiters also call them 'cucumber fish' because they smell like cucumber.
Īnanga life cycle
Of the five whitebait species, only the spawning habits of īnanga are fully understood.
- Eggs. Eggs are laid in estuary vegetation around the high-water mark on a very high tide (known as a spring tide). Males fertilise these, releasing so much milt (sperm) that īnanga have been dubbed ‘cowfish’, because of the milky water. Most adults die after spawning. The eggs are exposed for a number of weeks, but remain moist among the vegetation.
- Larvae. When another spring tide reaches the eggs, the larvae hatch. Then the falling tide carries them out to sea, where the hatchlings spend the winter, feeding on small crustaceans.
- Juveniles (whitebait). In the springtime, these young fish make their way upriver to live in freshwater habitats.
- Adults. By autumn the mature fish are ready to swim back downriver to spawn in the estuaries.
Īnanga normally live for one year.
Decline in numbers
Whitebait runs are generally smaller than they used to be, as many of their spawning grounds have been destroyed.
In most of the country the quality of river water has declined because of run-off from agriculture and other land use. The exception is South Westland, and it is probably no coincidence that this is where the best-known and largest whitebait runs still occur. There is no evidence that the runs there have declined.
Fresh water on the boil
It was once believed that whitebait went out to sea to spawn. But in 1904, one observer reported from the mouth of the Rangitīkei River in Manawatū:
‘During the months of March and April may be seen at high water spring tides countless myriads of small fish from four to six inches in length, making the water literally boil, wherever any rushes or brushwood exist by the river or creek margin. The water, much vexed, has a slightly milky appearance wherever the fish are most numerous. It is spawning time’. 1
Other species caught
On the east coast of the South Island, Stokell’s smelt (Stokellia anisodon) are taken by whitebaiters. Juvenile bullies, known as ‘whalefeed’ or ‘Dan Doolin spawn’, also find their way into nets on the West Coast. Glass eels, the juveniles of longfin and shortfin eels, also get caught as they migrate upriver in spring.