Sounds surveyed

Sounds surveyed

The wreck of the Soviet cruise liner Mikhail Lermontov which sank at Port Gore, Marlborough Sounds, on 16 February 1986. This image was created by NIWA using the same high-frequency side-scan sonar technology that we use for mapping seafloor habitats for FRIAs, marine conservation, and port developments. It can depict targets as small as a coffee cup or as large as a ship.

NIWA has just finished surveying almost all of Pelorus Sound, Marlborough, for Fisheries Resource Impact Assessments (FRIAs).

The Ministry of Fisheries requires a FRIA where people want to build a new marine farm, extend an existing farm, or renew a permit. NIWA works with groups of farmers to survey large regions, such as a bay or harbour, all at once. We provide them with detailed maps showing how the farms interact with each other and the environment. This approach is quicker, and more cost-effective, than piecemeal individual surveys.

‘We take high-frequency side-scan sonar images of the sea floor,’ says Ken Grange, NIWA’s Nelson Regional Manager. ‘This shows the types of habitats present, the proximity of any marine farm to ecologically important areas for fisheries resources, and whether the farms are located within their consent boundaries.

‘We also measure and model tidal currents and water movement to help us estimate the use of water and consumption of plankton by farms, showing where a bay can sustain more development and where it can’t. Farmers can also see where they could alter stocking densities or line spacing to manage the farms’ effects in various parts of the bay.’

Research subject: Oceans