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Sea Urchin Super-Diet Aids Improvements to Feed Quality

NORWAY - A new customised dry feed for sea urchins has generated international attention. Scientists at Nofima are now working on reducing production costs and adapting the formulation for large-scale production.

Many of the world's wild sea urchin stocks are over fished and poorer market access to sea urchin roe has led to increased interest in farming. But successful production relies on the correct feeding of contained sea urchin stocks and this is not always easy.

A total of 180 test sea urchins were individually studied. Here, they have received their own stall and an unlimited supply of feed.
Innovative Norwegian companies are among those that have started farming sea urchins. And Nofima has been developing nutritional strategies and feeds which aim to help captive production of these delicacies.

New Diet

Scientists at the institute (formerly Fiskeriforskning) have now developed a dry feed for sea urchins, which has won several feed trials. The good results have led to major demand from sea urchin farmers in a host of countries. The prototype for the successful feed is now being used in the entire Norwegian sea urchin industry, both wild-captured and farmed sea urchins.

"This feed is produced with a thought to nutrition and the sea urchin's biology. Sea urchins eat well with this feed and the growth of the row is also good" says Senior Scientist and feed developer Tor Andreas Samuelsen.

Feed for large-scale production

After consuming the new feed, the sea urchins were full of roe and displayed a very healthy colour.

However, the successful feed contains very expensive ingredients and has properties that are difficult to produce on a large scale. As a result, farmers do run the risk of insufficient supplies - not to mention inflated feed costs - leaving it difficult to achieve profitable production.

However Nofima's scientists are keen to tackle this dilemma. They see the potential of this 'super feed' and the research project is now substituting some of the most expensive ingredients with more economic alternatives. New technology is also being used to improve the processing system and the product, but without reducing the feed's high quality.

Further Trials Underway

"We have made changes to the recipe and commenced trials in Tromsø last December involving groups of 100 sea urchins receiving different types of feed, which are variants of the recipe," says Samuelsen.

Senior Scientist Sten Siikavuopio, who has closely monitored the sea urchins during the trial, says that the investigation exceeded all expectations.

"The sea urchins had a good appetite for all of the feeds and the roe had a wonderful size and colour," says Siikavuopio, adding: "Sensory tests will determine which feed is best."

Taste Judge Karla Vrbova assesses the quality of roe of sea urchins that have consumed the new feed.

Is the roe up to standard?

Following the trial, the sea urchins undergo sensory tests. A panel of trained taste judges determine whether the roe quality of the sea urchins that have consumed the new feed variants differs from the sea urchins that received the original super feed. The judges also taste the roe from the different test groups. "The method we utilise for judging the roe provides an extremely complex picture of the differences between the various products," says Mats Carlehög Head of Nofima's Sensory Laboratory in Tromsø.

The taste testers are specially trained to be objective and co-ordinated in their assessments. When the roe is served, they judge the properties of the consistency, taste, colour and smell.

The sensory tests, combined with the measurements of the sea urchins' growth and row size, provide the final answer about which feed recipe is best

"The results from the sensory tests are very promising and we have chosen to proceed with one of the feed types. The new recipe makes it both cheaper and easier to produce a good feed," says Samuelsen.

New equipment speeds up the process

Producing special feed for sea urchins is not simple. The feed must be dry, but must be able to sink down to the floor where the sea urchins are. It must have the correct shape and surface and, in addition, be able to last up to a week in water without dissolving. This is how long the sea urchin needs to consume the pellet.

To determine whether the feed production will function in a factory, Nofima in Bergen has invested in some new equipment to control the pellet quality relating to structure, strength, stability in water, density, sinking and floating qualities and fat intake. This equipment will improve the manufacturing quality of the feed, not just for shellfish, but also for other marine species such as salmon and cod.

"We have high expectations that we will achieve a feed with the same high quality as the original prototype, but which is suitable for large-scale production. If everything goes to plan, large-scale production at Felleskjøpet Agri will soon be possible," says Samuelsen.

The knowledge gleaned from this project will also be useful for solving research problems concerning feed production for king crabs and other types of dry feed for shellfish.

This project is a collaboration between Scan Aqua, Felleskjøpet Agri and Nofima, with support from Innovation Norway.