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Marine Science



Success for New Zealand trawl survey commissioned by Fisheries New Zealand and undertaken by the National Institute of Water and Atmospheric Research (NIWA), completed on 2 December.

The survey was the first in a series of 3 consecutive spring surveys with the aim of establishing the abundance and distribution of snapper, tarakihi, red gurnard and John Dory off the west coast of the North Island.

The survey ran from 25 October through to 2 December and covered the area from Mana Island through to 90 Mile Beach in the far North. It was the first survey of its kind conducted in the area since 1999.

Manager of Fisheries Science Dr Shelton Harley says the survey was a success, with 76 species of fish identified and nearly 19,000 fish measured aboard the RV Kaharoa research vessel. Extra biological information was also gathered for 5,600 fish, including individual weight per fish and maturity stage.

“We use the best available scientific information to manage our fisheries. This data will feed into the next stock assessment for these fisheries, and we will use it to make any changes to catch limits,” Dr Harley says.

“If a fish stock is doing really well we can increase the number people can catch, but if it’s not doing so well we will reduce catch limits to help keep the fish stock sustainable.

“It’s been almost 20 years since the last survey in the area. The information gathered for all species taken in the survey will improve our understanding of any changes in the marine environment since the last survey was done,” says Dr Harley.

Voyage and project leader Dr Emma Jones from NIWA says “This was a challenging survey to complete, with a total area of 34,636 square kilometres along an exposed coastline with several periods of bad weather.

“We successfully completed 111 trawl and acoustic sampling stations, and 19 acoustic-only sampling stations, ensuring we met all the objectives of the project.”

Alongside the targeted species, some rare and unidentified species were caught and will be kept for identification by NIWA and Te Papa scientists.

The research area included the West Coast Marine Mammal Sanctuary, so a Maui dolphin mitigation plan was developed for the survey. When the research vessel was in areas closed to commercial trawling, trawling was ceased and acoustic data was recorded instead.

A  Fisheries New Zealand observer onboard was responsible for carrying out marine mammal observations before and during each fishing event on the trip. No Maui dolphins were sighted during the survey, however, there were sightings of common dolphins, a pilot whale, and 1 unidentified whale.

The results of the survey will be reviewed by a Fisheries New Zealand Science working group in early 2019, with the report being published later in the year.

The next survey for the west coast of the North Island is planned for October 2019