Aquaculture for all
The Fish Site presents: The Vienna Sessions - Conversations about aquaculture. 9 video interviews with aquaculture thought leaders. Watch here.

Seafood Vacuum Cleaner More Effective for Harvesting Sea Urchins

Sustainability Technology & equipment +2 more

NORWAY - Several tests show that the remotely-operated underwater vehicle (ROV) Seabed Harvester beats the divers when it comes to harvesting sea urchins one of the worlds highest paid seafood products.

Lucy Towers thumbnail

Several companies have attempted to establish commercial harvesting of sea urchins along the Norwegian coast. There are currently only a couple of companies harvesting wild sea urchins, but the high kilo price means there is major interest in this product.

One of the main bottlenecks for the development of a sustainable sea urchin industry is a reliable and cost efficient harvesting method.

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 market demands regularity of supply and companies cannot only supply sea urchins at particular times of the year.

The ROV has previously been tested in good weather conditions in summer. During the winter scientists from the food research institute Nofima also tested the ROV during the Polar Night, when the weather is at its worst.

The tests took place in January in Btsfjord in Finnmark. Strong winds meant that the estimated temperature was as low as -40 C. This is too cold for divers, but the ROV could still operate normally.

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. This is higher than what was previously harvested using divers, around 91 kg per day.

This shows that in all likelihood Seabed Harvester is the most efficient harvest method for sea urchins in demanding winter conditions in Northern Norway, says Scientist Philip James from Nofima.

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.

The ROV may also be used to inspect seabed conditions and stocks over larger areas.

In order to achieve the most efficient harvesting possible, it is important to map the sea urchin stocks in the area prior to the harvest commencing, says Mr James.

Long-term approach

Estimates show there may be up to 80 billion individual sea urchins along the Norwegian coast, which constitutes 56,000 tonnes. The market value of these sea urchins has been calculated as NOK 6.2 billion by Nofima.

We have never harvested more sea urchins than we did during the test with the ROV. In Btsfjord, where we operate, diving is very unpredictable and 200 days a year the weather is too extreme to use divers, says 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.

Several things remain before the ROV may be used in an optimal manner, including the support vessel being better adapted to the ROV.

An ordinary fishing boat was used during the testing, which was not ideal for the purpose, says Mr James.

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.

The scientists are also studying various ways of increasing the proportion of the catch that may be used, such as utilising the by-products in a better way. They will also attempt to harvest other species using the ROV technology.

The ROV was developed by Are Hofstad from Norwegian company 7S-Technology AS.

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 Mr Hofstad.

The ROV is very gentle on the seabed, which makes it ideal for harvesting other species. We are also anticipating a significant improvement in the harvest rate when the operators become more experienced.

The research is financed by the Norwegian Seafood Research Fund (FHF) and is being carried out in collaboration with Norway Sea Urchin AS and 7S-Technology AS.