Our soft extruded pellet. MaGro tuna feed is a soft extruded feed, which is unique in Skretting. The pellet can be squashed, without breaking. Due to this unique soft texture tuna easily accept the diet.
Today, two species of tuna are farmed in full cycle, from egg to harvest size. These are Pacific bluefin tuna (Thunnus orientalis) and Atlantic bluefin tuna (Thunnus thynnus). Pacific bluefin breeding is the most developed commercially, and produced in Japan. Some commercial breeding activities with Atlantic bluefin also take place in the Mediterranean Sea. Adult tuna are kept in large pens at sea until spawning. After spawning, eggs are collected and brought to hatcheries.
In hatcheries, eggs will hatch under controlled conditions to produce a larvae. Approximately 20 of these hatcheries are currently active in Japan, producing Pacific bluefin tuna, and a handful are active in the Mediterranean region, producing Atlantic bluefin tuna. Overcoming the mortality of larvae is a big challenge for various reasons, but as more knowledge becomes available, survival rates have gone up.
Juvenile tuna are stocked in large sea pens. In Japan, it's estimated that over 500 000 individuals per year come from hatchery operations. The rest are caught in the sea and carefully transferred to the sea pens. After stocking, the critical period of weaning the fish to feed starts. Our research has shown that within 20 days, wild caught tuna fully accept MaGro. Hatchery raised tuna are already used to formulated diets and immediately accept these.
The grow-out of tuna also takes place in sea pens; often the same as when they were juveniles, though farming operations are sometimes moved further offshore. Here, fish are fed daily with MaGro until they reach harvest size. Harvest size can vary between different operations and juvenile size. Typical harvest size is anywhere from 40 to 200 kilos.
20 years in the making: Skretting launches breakthrough tuna diet
A new diet aimed at helping tuna farmers avoid the biosecurity risks and sustainability issues associated with baitfish diets has been launched by Skretting. Now available in Japan, MaGro is a soft extruded feed for bluefin tuna that has been created using patented production technology.
In 2011, Kagoshima University and Skretting Japan built an aquaculture research centre called Kagoshima ARC at the university. The research centre performs feed studies under closely controlled conditions, and the academic competence of the university combined with Skretting's global network provide great opportunity to develop innovative new feeds.
Skretting participates in a number of research collaborations, and in 2011, the EU-funded Translation of domestication of thunnus thynnus into an innovative commercial application (TRANSDOTT) project resulted in successfully breeding Atlantic bluefin tuna.