Mapping the Wairoa Hard

A joint project between Hawke’s Bay Regional Council and NIWA with MPI co-funding aims to map a part of the Hawke Bay seabed known as the Wairoa Hard.

The Wairoa Hard covers just over 300 square kilometres of northern Hawke Bay between Moeangiangi and Wairoa Rivers and extending out 18 kilometres to where the ocean floor is 50 metres deep.

It is named for its coarse cobble substrate and is an area of national importance as it provides a nursery for juvenile fish, snapper, sharks, John Dory and trevally.

“This is an area that has been identified as significant in the coastal marine area for a number of services and functions, but we don’t know how it is doing health wise and we need a much better understanding of that,” says Anna Madarasz-Smith, HBRC senior coastal scientist.

NIWA’s multipurpose coastal research vessel the ‘Ikatere’ arrived in Hawke’s Bay on Thursday 12 April. It is a 13.9m custom-designed catamaran which collects high-quality hydrographic data and has been involved in the mapping of more than 1,500,000km² of New Zealand’s seafloor using multibeam echosounder equipment. 

NIWA staff will use multibeam mapping technology to map the shape and contours of the seafloor and identify different seafloor physical characteristics.

“These include the type of substrate or sediment (eg, hard gravel or soft mud) and what else is on and above the seafloor such as cables, kelp beds and biological aggregations (schooling fish),” says NIWA marine geology principal technician Steve Wilcox.

The mapping will take 10 days.  This will be the first part in a programme to assess the current state of the Wairoa Hard.

The Wairoa Hard was closed to net fishing in 1981 and since then no assessment of its state has been made.   

Photo: Ikatere heading for the Wairoa Hard

13 July 2018

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