Researchers Find Offshore Aquaculture has a Low Nutrient Footprint

December 11, 2019

Large-scale offshore aquaculture may have much less environmental impact from nutrient pollution than people suspect, according to a recent study funded by Florida Sea Grant and NOAA Fisheries.

Offshore aquaculture is poised to grow in the coming years to help offset a $15.8 billion U.S. seafood trade deficit. Expanding aquaculture to complement wild-capture fisheries can increase and diversify U.S. seafood production and stabilize U.S. seafood supply in the face of environmental change and economic uncertainty. Along with the opportunities that offshore aquaculture presents, concerns have been raised about the potential for fish waste to pollute surrounding waters by introducing unnaturally high nutrient levels, which can cause issues common in nearshore areas, such as harmful algal blooms.

According to the new study, researchers found little evidence of nutrient pollution from a commercial cobia aquaculture farm located offshore the Republic of Panama. In the water column downstream of the farm’s cages, they found no changes to nutrient concentrations that often cause concern, such as nitrogen and phosphorus. They did find modest increases to nutrients in the seafloor sediment, but explain that conscientious management could reduce this type of nutrient build-up. For example, leaving cages empty for a period of time between fish harvest and restocking has been shown to reduce nutrients from building up in the sediment under cages.

“This study is of great interest to all stakeholders concerned with the expansion of offshore aquaculture in the United States and other countries,” stated the study’s co-author Daniel Benetti in a news release from the University of Miami Rosenstiel School of Marine and Atmospheric Science. “To our knowledge, this is the first report of its kind from a commercially scaled aquaculture facility utilizing offshore submersible cage technologies.”

Read more about aquaculture work funded by Sea Grant.

Read more about NOAA Fisheries Office of Aquaculture.

Read an earlier article about Benetti’s Sea Grant-funded research.

This study was supported by the NOAA Sea Grant Aquaculture Research Program (project number NA10OAR4170079) and the NOAA Marine Fisheries Initiative (grant number NA12NMF4330087).

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