Marking inanga spawning sites beside the Avon River in Christchurch.

Image: Shelley McMurtrie | ©

Introduction

Every year there are fewer whitebait in our streams and rivers. Find out what you can do to help increase whitebait populations.

Why whitebait are in decline

Whitebait prefer to live in bush-covered streams. In the last 100 years we have lost a huge amount of whitebait habitat (for spawning as well as adult fish habitat) by draining wetlands, artificially channelling small streams and removing vegetation beside streams.

Adult whitebait need clean water and healthy waterways to live in and breed. Pollution from land reduces the water quality in streams and rivers and introduced plants clog up the places where whitebait live. Sediment also blocks the spaces between stones on the stream bed, reducing the habitat for invertebrates, which adult fish feed on.

Barriers in waterways, like dams and overhanging culverts stop migrating whitebait from reaching better habitat upstream. 

Introduced sports fish like trout and pest fish like gambusia compete for habitat and prey on whitebait. Whitebait fishing is also thought to contribute to the decline, but its impact is not known.

How we can turn the decline around

There are many ways we can help increase whitebait populations:

Prevent the spread of didymo

Didymo is an exotic alga that invades waterways. To prevent the spread of freshwater pests such as didymo, always check all footwear (including waders), vehicles, fishing equipment and other items are clean and dry before entering, and when moving between, waterways.

See Biosecurity New Zealand for more information and cleaning guidelines.

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