Grows best at 10 degrees
The water temperature is of major importance for how well juvenile sea urchins grow, new research trials by Nofima show.
Temperature is the most important growth regulating environmental factor for all poikilotherms, including sea urchins. In the wild the green sea urchin is found in water temperatures ranging from -1 to +20 °C. The scientists have charted how quickly juvenile farmed sea urchins grow at different water temperatures and consequently how much feed and water they need to achieve optimal growth.
Specially made feed
A dry feed recently developed by Nofima specially for juvenile green sea urchins was used for the trial. During the trial period from October 2009 to April 2010, five groups of artifically hatched sea urchins were fed this feed in tanks with different water temperatures (from 4 to 14 °C) .
Major connection between food and heat
The report points to the fact that there is a linear connection between feed intake and temperature.
Taking all results together, a temperature of 10 °C proved to be the optimal temperature when feed conversion and growth are viewed together.
The average feed fator (grams of feed per gram of growth) for the group at 10 °C was two – in other words 2 grams of feed per gram the sea urchin grows. It was the case, for instance, that the sea urchins kept at 14 °C required four times as much feed to achieve the same weight increase.
In the light of this systematic work, the scientists have prepared a growth model showing feed intake for different sizes and temperatures and a water requirment table for green sea urchin
“This project started thanks to the good collaboration between Sea Urchin Farm AS and Nofima. The Regional Council for Western Norway has been one of the funding sources, and contributed to the project being able to be implemented,” says Project Manager Sten Siikavuopio.
Open seminar on sea urcins
The results from several different sea urchin projects will be presented during the Fishery and Aquaculture Industry Research Fund (FHF) sea urchin seminar “From problem to resource” in Tromsø on March 17.
“The purpose of this seminar is to shed light on the challenges involved in the commercialisation of harvesting and selling sea urchins, as well as presenting the experiences which have been undertaken. In addition, we would like to receive suggestions about new development projects in order to get commercial harvesting of sea urchins started,” wrote FHF in its invitation.