IIMPROVING FARMED FISH HEALTH WITH THE RED MACROALGAE TURKISH TOWEL Chondracanthus exasperates
Terrestrial plant proteins have been shown to adequately replace a portion of the fishmeal used in aquaculture feeds for a number of species. Complete replacement has yet to be achieved due to nutrient deficiencies and species-specific sensitivities. Macroalgae contains many essential nutrients that are limiting in terrestrial plants (i.e. trace minerals, omega-3 fatty acids, amino acids). There also appears to be health benefits associated with the use of macroalgae in aquaculture feeds for some fish species. The combination of the two ingredient types shows great potential for the complete replacement of fishmeal and fish oil in aquaculture feeds. Recent studies at NWFSC have shown improvements in feed intake, growth, and liver histomorphology when the red macroalgae Turkish Towel Chondracanthus exasperates was added to plant-based feeds for sablefish (Anoplopoma fimbria) a cold-water marine fish of the Eastern Pacific Ocean.
A feeding and disease challenge study was conducted in 2019 to evaluate the health benefits associated with a 10% addition of Turkish Towel to an alternative, plant-based feed for juvenile sablefish. An additional experimental feed was evaluated which included the addition of 1% Macrogard (beta-1,3/1,6 glucans) to a plant-based feed. When macroalgae is added, wheat flour and soy protein concentrate are removed from the formulation to maintain similar protein content among experimental feeds. Two experimental feeds were prepared in addition to a standard plant-based feed formulation, used as a control .
The disease challenge was carried out at NOAA's Newport, OR laboratory with atypical Aeromonas salmonicida according to standard laboratory protocols. There were no mortalities in the no pathogen controls . When Turkish Towel was used as a supplement in the plant-b ased diet, sablefish had significantly greater survival than fish fed either the plant-based control or beta-glucan feeds.
