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'Fish-free' diet created for farm-raised carnivorous fish'Fish-free' diet created for farm-raised carnivorous fish

Best performing "fish-free" diet contains algae oil rich in essential omega-3 fatty acids.

August 25, 2020

4 Min Read
Ocean Era kampachi.jpg
A kampachi, or almaco jack, being measured during a fish-free feed study at the Ocean Era facility in Kailua-Kona, Hawaii.Credit: Ocean Era Inc.

Researchers in Kona, Hawaii, have made a breakthrough in the effort to develop a cost-effective "fish-free" feed for farm-raised kampachi, also known as almaco jack — a carnivorous marine fish desired for its rich, buttery flavor, according to an announcement from mariculture company Ocean Era Inc., which was involved in the research.

The ability to replace fish meal and fish oil currently used in carnivorous marine fish diets will have important implications for ocean sustainability and meeting the growing demand for seafood around the world, the announcement said.

The trial results are detailed in a technical article in the Global Aquaculture Alliance's Advocate.

"This is the first time — to our knowledge — that fish meal and fish oil have been totally eliminated from the diet of a marine carnivorous fish, with no deleterious consequences," said Neil Anthony Sims, chief executive officer of Hawaii-based Ocean Era, where the trial was conducted. "Kampachi are a fast-growing, sashimi-grade fish, so this a significant breakthrough for the sustainability and scalability of marine fish farming."

Aquaculture, the world's fastest-growing food sector, consumes more than 70% of the world's fish oil and fish meal, which are derived from forage fish like sardines, anchovies and menhaden, the company said. Each year, roughly 20% of the global wild catch, or 18 million tons of fish, are converted into fish meal and fish oil for use in animal feed.

During the three-month trial, 480 juvenile kampachi (Seriola rivoliana) were fed one of four diets. Two of the diets contained no fish meal, and one of these also contained no fish oil, the announcement said.

Ocean Era explained that fish meal replacement relied primarily on poultry meal from upcycled poultry trimmings. Fish oil replacement was achieved using a proprietary natural marine algal oil (Vermaris) containing high levels of two critical omega-3 fatty acids: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). A fish meal and fish oil diet was used as a control, together with an additional commercial control diet. The fish were stocked into 16 tanks for the comparative growout trial.

The fish fed the zero fish meal/zero fish oil diet performed as well as the fish fed the fish meal and fish oil diet. Performance was evaluated in terms of growth, feed conversion ratio, fillet yield and survival.

The fish fed the zero fish meal/oil diet also had a more desirable taste compared to the fish fed the commercially available control diet, the announcement said.

"The results clearly show that algal oil can replace fish oil 100% without any reduction in growth of this marine fish," said Rick Barrows, a fish nutrition expert with Aquatic Feed Technologies and co-principal investigator of the study.

The feed formulations used in this trial are available as open source formulae through the F3 Feed Innovation Network (F3 FIN) for anyone working to replace wild-caught fish ingredients in animal feed, Ocean Era said. F3 FIN encourages sustainable innovations in fish-free aquaculture feed ingredients by sharing experimental protocols, testing facilities and ingredient providers.

Algae oils have been shown to contain twice the amount of EPA and DHA omega-3 fatty acids as fish oil, both of which are important for maintaining fish health and imparting heart and brain health benefits to people.

"Development of diets that use these upcycled ingredients and microalgal oils is critical to the long-term scalability of marine fish culture and, therefore, to our ability to sustainably feed a planet of 9 billion people with heart-healthy seafood," Sims said.

The project, titled "Developing Cost-Effective Fish Meal-Free & Fish Oil-Minimized Diets for High Market Value U.S. Marine Fish Aquaculture," was funded through the National Oceanic & Atmospheric Administration 's(NOAA) Saltonstall-Kennedy Grant Program. The U.S. Department of Agriculture's Agricultural Research Service provided feed milling support for the trial. Anthropocene Institute and Ka'upulehu fishponds were collaborating partners on the NOAA grant.

The Saltonstall-Kennedy Grant Program funds projects that address the needs of fishing communities, optimize economic benefits by building and maintaining sustainable fisheries and increase other opportunities to keep working waterfronts viable.

Ocean Era (formerly Kampachi Farms LLC) is a research and development company based in Kona, Hawaii, that's dedicated to softening humanity's footprint on the seas by expanding production of the ocean's living resources.

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