Remotely-operated underwater vehicle (ROV) Seabed Harvester. (Photo: Nofima)
Tests reveal best harvester of sea urchins
Friday, October 12, 2012, 22:40 (GMT + 9)
Several tests show that the remotely-operated underwater vehicle (ROV) “Seabed Harvester” beats the divers when it comes to harvesting sea urchins.
Traditionally, sea urchins have been harvested by divers. But the extreme conditions in Northern Norway, with cold temperatures, limited light and strong winds, make it difficult to dive for sea urchins in winter.
The ROV has previously been tested in good weather conditions in summer. During the winter scientists from Nofima Mat, the Norwegian Institute of Food, Fisheries and Aquaculture Research also tested the ROV during the Polar Night, when the weather is at its worst.
The tests took place in January in Båtsfjord in Finnmark. Strong winds meant that the estimated temperature was as low as -40 °C -- too cold for divers.
After four days the ROV had harvested a total of 1.88 tonnes, of which 35 per cent was high export-quality sea urchins. A full 52 per cent of the catch was of sufficient quality to be sold.
The average daily harvest using the ROV was 146 kg -- higher than what was previously harvested using divers, 91 kg per day.
“There are several factors that make it more efficient than the divers. It can be used during winter, in poor weather conditions and at greater depths, while the sea urchins are of the same quality as those harvested by the divers,” said Scientist Philip James from Nofima.
The ROV may also be used to inspect seabed conditions and stocks over larger areas.
Estimates show there may be up to 80 billion individual sea urchins along the Norwegian coast, or 56,000 tonnes. The market value of these sea urchins has been calculated as NOK 6.2 billion (EUR 840.1 million) by Nofima.
“We have never harvested more sea urchins than we did during the test with the ROV,” said Mattis A. Tangeraas, General Manager of Norway Sea Urchin AS. “The ROV cannot operate 50 days a year so that will give us an additional 150 harvesting days per year. But in order to gain financing for such an ROV, long-term testing needs to be carried out over several months in order to confirm the potential.”
James added: “Among other things we used a lot of time to manoeuvre the boat and position the anchors, meaning there was less time available to harvest sea urchins. Consequently, the amounts harvested are on the conservative side. With a better adapted mother vessel, the amount harvested will increase.”
“We started with harvesting sea urchins, but the goal is to use the ROV to harvest other species, including scallops and other crustacean species,” says Hofstad.