Fishers help protect coral

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The lace coral beds on the seafloor at Separation Point in Golden Bay–Tasman Bay are thriving – and commercial fishers can take much of the credit.

Back in the late 1970s fishers realised these beds were under threat from heavy fishing gear and that they were important nursery areas for juvenile commercial fish. The beds were subsequently protected under fisheries regulations in 1980.

Scientists from NIWA have just completed the first extensive survey of Separation Point since its protection, supported by the Ministry of Fisheries’ biodiversity research fund, reports the latest issue of Aquatic Biodiversity & Biosecurity.

The research showed that there were large mounds of bryozoans throughout the centre of the protected area. A small dredge sample contained 37 species of bryozoans and over 40 species of associated invertebrates, confirming the significant biodiversity of the community. Bryozoans are ecologically important because they increase habitat complexity and provide shelter for prey and predators.

NIWA scientist Ken Grange said that it was unusual to see colonies living on the muddy seafloor.

“They normally need rocks or shells to settle on and grow,” he said.

Dr Grange said they used two separate methods to survey the area.

“We used side-scan sonar to provide the equivalent of an aerial photograph of the seafloor, and then we identified whether or not these images were representative of bryozoan communities by using a small Remotely Operated Vehicle (ROV) to avoid the dangers of diving repeatedly in deep water with poor visibility and strong currents.

“The ROV is equipped with a high-resolution video camera, so we were able to record the video on the vessel as the ROV ‘flew’ over the seafloor.

“If it hadn’t been for the foresight of commercial fishers in 1980, this important habitat might have disappeared because it’s unlikely that new bryozoan mounds could establish directly on soft mud once broken up by fishing gear,” said Dr Grange.

For more information, contact:

Dr Ken Grange
Phone +64 3 548 1715
Mobile +64 25 451 200

Geoff Baird
Communication Manager
Phone +64 4 386 0543
Mobile +64 25 229 6314

Research subject: Coral