It is reported that Skretting has launched an upgraded Gemma Micro Artemia replacement for the marine hatchery market. It is said that this is a reliable supply of optimised nutrition to follow rotifers, improving growth rates and reducing costs. The upgraded Gemma Micro was trialled in several leading hatcheries in Spain, France and the USA during 2009 with impressive results. All hatcheries reported the diet is easy to use whether feeding by hand or by automated micro-feeders.
According to the information this new feed spreads readily on the water surface and sinks slowly. Fish larvae were quick to adapt to the feed, which Skretting recommends is co-fed with rotifers over the first few days after introduction using a simple meal feeding technique developed by Skretting. This moderates the speed of passage through small larvae to ensure they benefit fully from the nutrition.
Eamonn O’Brien, Product Manager for Skretting Marine Hatchery Feeds, explains the reasoning. Marine larvae in the wild eat a wide range of organisms including marine algae. Its aim is to mimic this natural diet. High quality algae are also vitally important in the live feed period and it is logical to formulate replacement or weaning diets with this in mind.
In the hatchery trials, Gemma Micro led to significant improvements in growth rates compared with conventional Artemia diets. For example, at a hatchery in Spain sea bream at day 65 averaged 246 g compared with 176 g for Artemia-fed controls. Survival rates were the same or better; in some instances the improvement was substantial — up to 30 percent higher.
The quality of Artemia has become erratic in the recent past. Lower hatching rates and poor separation mean more work to provide an adequate supply of nauplii. In marine hatcheries Artemia can represent 50 percent of total feed costs as well as requiring extra time and energy.
