Floods postpone Biosecurity New Zealand investigation in Northland

5 April 2007

Northland's devastating floods have delayed research and local meetings Biosecurity New Zealand had planned to learn more about an Australian sea squirt which bloomed in the Bay of Islands late this summer.

The squirt, with the Latin name Eudistoma elongatum, looks like clusters of white or cream coloured tubes, and had appeared in a handful of locations in the Bay of Islands – in the Waikare Inlet, Opua, Paihia and on oyster farms in Houhora and Parengarenga Harbours.

A team from Biosecurity New Zealand was set to visit Northland next week to meet with the regional council, tourism and aquaculture industries and iwi to discuss the impacts of the squirt, potential management options and view the squirt in the field.

The visit has, however, been postponed due to the floods, as recovery work is keeping many key personnel otherwise occupied. As well, the deluge appears to have affected the squirt, causing it to disappear or at least be harmed by the torrents of fresh water.

Biosecurity New Zealand Senior Marine Advisor Dr Peter Stratford says very little is known about Eudistoma elongatum, other than that it poses no environmental concerns and has minimal impact on the aquaculture industry in its native Australia.

"It blooms each season, appearing in late summer and reducing in volume or dying off over the winter. This seasonal behaviour, plus the impact of the floods, means the research we need to do is now likely to take place at the beginning of next summer, if and when it reappears after winter."

"What is clear is that Eudistoma is relatively widespread in the Bay of Islands area and any measures taken in response are likely to be focused on managing and controlling the species, rather than eradication."

Eudistoma elongatum is part of the same biological family (ascidians) as the Styela clava sea squirt populating Auckland's Hauraki Gulf and found in small numbers in the Tutukaka Marina in Northland, but is a very different organism.

"The Auckland Styela clava situation has clearly shown us the difficulties in eradicating pests in the marine environment," Dr Stratford says.

• Media contact: Lesley Patston, Biosecurity New Zealand Senior Communications Adviser 029 8940163

Further info: www.biosecurity.govt.nz/pests/surv-mgmt/surv/marine

To report an exotic pest or disease, call the MAF Emergency Pest and Disease Hotline: 0800 80 99 66.