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Ever wondered what’s new in the world of fish feed? Well, you’ve come to the right place. Tim O’Hara, Feed Manager, recently shared a variety of information about Marine Harvest’s improvements and expanding knowledge in this key aspect of aquaculture.
Although advances continue to be made in feed formulas, the focus remains on top quality raw materials. Marine Harvest fish are currently fed a feed that is 15 to 18% fishmeal and approximately 13% fish oil. The balance comes from poultry meal, corn gluten and vegetable oil.
A feed trial, undertaken at Doctor and Brougham Point sites in 2009, reduced the level of fish oil to 7% and was designed to minimize use of marine raw materials. “During the trial we experienced lower growth and an increased feed conversion rate (FCR) compared to our standard diet”, said Tim, adding that this led to less economic viability. Standard diets have been resumed but research into fishmeal and oil replacement continues.
Much media attention has been focused on the levels of contaminants in fish feed, such as dioxins and PCBs. These toxins naturally accumulate in fats and therefore are found primarily in the fish oil portion of the feed.
There are two main ways to decrease these levels – use fish oil from areas where the contaminants are lower, such as Chile and Peru and use less fish oil. Using both factors has reduced contaminant content of feeds by ¾ of mid 1990 levels stated Tim.
Although organic pollutants in fish are a small fraction of Canadian Food Inspection Agency (CFIA) warning levels, the importance of research into feeding fish, diets that substantially reduce fishmeal and oil continues from a sustainability perspective.
Enter Dr. Erin Friesen, Product Manager at Skretting North America in Vancouver. Erin focused on this hypothesis during her PhD research at UBC. Following lab and site trials with both farmed and wild salmon, she concluded that when fed a diet rich in land-based sources of oil such as flax and canola, contaminant levels in farmed fish were comparable to their wild counterparts. At the same time, farmed fish had higher levels of healthy Omega-3 fatty acids than the wild fish.
Erin’s research findings were published in the scientific journal Environmental Science and Technology in April 2008.
How much feed fish are given is a key component of both healthy fish and the economic bottom line.
Tim said, “We feed purely to the growth potential of the fish.” This means they are fed to the point where they will grow the most rather than to the point where they feel “stuffed”.
We stop feeding when they’re still actively eating because that extra nutrition isn’t needed for their growth, explained Tim. To put it another way, “feed intake is seen as an energy equation, not a volume equation,” added Tim.
This improves not only our FCR but influences the Fish In Fish Out (FIFO) ratio as well. FIFO refers to “how much wild fish it takes to create one kilogram of farmed salmon”. The International Fishmeal and Fish Oil Organization (IFFO) provides a clear explanation, suitable for the non-scientific reader, of the science behind accurately calculating the amount of wild fish needed to produce farmed fish. For more information, please visit www.iffo.net.