Whitebait find new sites to lay eggs post Canterbury earthquakes

Whitebait may be the unsuspecting beneficiaries of the Canterbury earthquakes.

Shane Orchard carrying out whitebait research work in Christchurch

Whitebait eggs have been found in areas where none have previously been seen four years after the quakes devastated the lower reaches of the Heathcote River and its mouth at the Avon-Heathcote estuary.

Adult whitebait lay their eggs in streamside vegetation in the area where saltwater mixes with fresh river water, says University of Canterbury doctoral researcher Shane Orchard.

The PhD research investigates the vulnerability of coastal conservation areas and Mr Orchard is using earthquake effects to simulate the type of issues that might occur with climate change.

Whitebait have been in decline and management is an ongoing conservation issue.

Because of uplifting and liquefaction at the river mouth, the local pattern of saltwater intrusion is thought to have changed and large numbers of whitebait eggs have now been found in the lower Heathcote River, closer to the estuary than ever seen before.

"I am exploring the salinity environment in the lower reaches of the Christchurch rivers to get a better picture how this might affect whitebait spawning sites and ways they can be protected," Mr Orchard says.

"This result shows that these important sites have indeed been on the move."