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22 “For the industry as a whole, the waste-load allocation mandated a 40 percent reduction of total phosphorus discharged from the baseline in the early ’90s,” Fornshell said, “so that waste-load allocation was put into producers’ permits.”

A Profitable Partnership Using feed formulations and new ingredients to improve standards

Solution: Producers come into compliance Years later, data shows that aquaculture producers have met that guideline and gone beyond it, Fornshell said, and those efforts to meet the TMDL came on several fronts.

First is oversight. Several agencies regulate the aquaculture industry in Idaho, according to the state DEQ website. In addition to the EPA and DEQ, commercial aquaculture facilities must be licensed by the Idaho State Department of Agriculture (ISDA) as well as have their effluent control facilities approved by DEQ. The Idaho Department of Water Resources (IDWR) oversees water rights for facilities, and the Department of Game and Fish and other agencies also play a role. “In terms of trout farming and flowthrough systems, Idaho has been at the forefront of oversight for responsible aquaculture,” Fornshell said.

Second is construction of aquaculture facilities. Idaho has cold-water operations for trout steelhead, salmon, and sturgeon, and warmwater facilities that raise catfish and tilapia. Whether operators use a set of ponds or earthen or concrete

Peter Fritsch, president of Rushing Waters Fisheries

Peter Fritsch, president of Rushing Waters Fisheries near Palmyra, Wis., has been seeing phosphorus discharge numbers go down and production numbers go up for most of his 21 years in aquaculture. “Feed producers have been working on better formulations for years,” Fritsch said. “Feed conversion rates have gotten better and better.” The Rushing Waters trout farm sits on 80 acres and has 56 flow-through ponds or earthen raceways and nine artesian wells. Water is discharged back to the natural waters of Wisconsin. “This business is about the slow process of raising good fish, but it’s fastpaced too because every day there are challenges,” Fritsch said. In 2015, the challenge seemed almost insurmountable. The state’s

raceways, situated in series or in parallel, all operations must be built to minimize the release of nutrients and solids to surface or groundwater and comply with permit requirements.

The third component addressed was diet. As Fornshell shared, phosphorus is an essential mineral for fish growth. But research has been ongoing to determine dietary requirements for fish farming.

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Aquafeed vol 11 issue 1 2019