by Dan Burden, content specialist, AgMRC, Iowa State University, djburden@iastate.edu
Profile revised February 2008 by Diane Huntrods, AgMRC, Iowa State University.
Overview
The walleye (Stizostedion vitreum) is a high-value game and food fish in the north central United States. The walleye is a species of large perch; the commonly used names “walleye pike” or “walleyed pike” are misleading. Driven by a decreasing commercial catch and strong market demand, there is a strong interest in developing this species as an aquaculture-produced marketable fish.
Commercial Fishing
There is little or no commercial walleye fishing in the United States. To protect sport fisheries, most commercial fishing on America’s larger lakes and rivers has been prohibited for decades. The exception to this rule are the Native American tribal fisheries in Wisconsin, Minnesota and Michigan that allow a tribal spring spearing and netting harvest as established by treaty regulation. These fish are used by the tribes and not legally sold onto the open market.
Most U.S. restaurant and market fish come from commercially fished U.S. wild populations in Lake Erie and Canadian sources that include Lake Winnipeg, Lake of the Woods, Eagle Lake, Lake Nippigon and similar large lakes.
Aquaculture
To maintain sport and tribal stocks, the United States and Canada yearly produce over 1 billion fry for stocking programs. The fish is relatively easy to hatch and rear in aquaculture systems. Aquaculture fish producers use fry that are produced on site or are purchased from other operations. Private producers also produce fry for private stocking of lakes and rivers by lake associations, sport-fishing groups and individuals. Traditional rearing methodology involves the capture and egg collection from wild brood stock, and subsequent rearing in pens or tanks until they are released (planted) into a lake or river in the fall. These are the preferred fish for release into the wild.
Since the early 1990s, aquaculturists interested in producing fish for the market have focused on a “saugeye” hybrid. This fish was developed by crossing a female walleye and a male sauger (a closely related species). The fastest growing and most aquaculture-tolerant fish for pen- or tank-rearing systems is known as SL/MR, denoting the origins of the female walleye (Spirit Lake Iowa) and the male sauger (Mississippi River). This cross grows to market size more than twice as fast as native fish in closed-system rearing facilities. Also, walleyes exhibit sexually dimorphic (sexually different) growth characteristics. In walleyes and walleye hybrids, females grow faster than males. It has been demonstrated that there is the potential to hormonally shift “phenotypically invert” the sex of fry, so that they develop into monosex female populations. This could be a production boon to the industry; however, regulatory and public-perception barriers resulting from hormone use would need to be addressed.
Walleyes and saugeyes may have their growth rates retarded if too intensively concentrated in tank or pond systems. Research is ongoing into proper densities for tank-rearing systems. Additional work is focusing on outdoor pond and net-rearing systems. Much of the technology for these systems relies on information established for the culture of the related yellow perch, although there seems to be no advantages to this system over tank rearing. The optimal growth for walleyes is 68°F to 77°F. Nutritionally optimal diets are well established.
Production and Sales
Of the 68 U.S. farms raising walleye in 2005, Minnesota was home to 24 farms and Wisconsin was home to 16. Other states involved in walleye production include Iowa and New York with five farms each, and Michigan and South Dakota with four farms each. When size category is considered, 37 farms raised fingerlings and fry, and 30 raised stockers. (Source: Census of Aquaculture 2005, USDA, October 2006.)
The price per pound of walleye as a food fish is among the highest of freshwater fish. Total sales of farm-reared walleye was about $1.4 million in 2005. Of that amount, Minnesota sold $700 thousand and Wisconsin sold $291 thousand. The total sales of fingerlings and fry was $916 thousand in 2005 and of stockers was $417 thousand. (Source: Census of Aquaculture 2005, USDA, October 2006.)
Profile created July 2004 and revised February 2008.