Reservoir ranching is overall, a highly sustainable, extensive (little to no input of feed, generated energy or other technology) culture system in which young hatchery-produced fish are stocked at low densities (25-75/ha) (10-30/acre) in existing freshwater reservoirs, feed on naturally available foods, and are harvested when they reach the desired size or age.

Since the hatchery rearing stage of reservoir ranching involves feeding of pelleted diets, sustainability is lower than in the grow-out stage after stocking in the reservoir. Paddlefish stocked for reservoir ranching would be harvested for caviar at the age when females are mature and for meat when the fish reach the appropriate size for the market.

Reservoir ranching can be practiced in private reservoirs, where the fish are owned by an individual or other business entity, or in publicly owned waters, where a government agency manages the fishery and harvest is performed by licensed commercial fishers. Reservoir ranching has long been practiced in China and other Asian countries for food fish production. 

Reservoir ranching is part of a larger group of practices known as culture-based fisheries. In the United States, culture-based fishery practices are used by government agencies to enhance sport fishing opportunities. These practices include introducing new and sometimes exotic species, stocking natural and man-made water bodies, supplementing with fertilizer, engineering the environment for habitat modifications and improvements, altering species composition by eliminating undesirable species and stocking only select species, and introducing genetically manipulated 
or modified species.
Reservoir Ranching
Copyright 2012, Kentucky State University - Frankfort, KY 40601

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The United States has millions of hectares (acres) of surface water impounded by dams. Reservoirs in the USA were constructed for much the same reasons as elsewhere in the world: flood control, water storage and hydropower. However, state and federal regulations and resistance from some user groups have prevented the use of reservoirs for aquaculture in any form in the USA, and recreational fishing, boating and scenic views have taken precedence over commercial production of fish.

In 2006, the Kentucky Department of Fish and Wildlife Resources issued new regulations allowing private individuals to contract with small municipalities on a profit sharing basis for ranching of paddlefish in potable water supply reservoirs. These reservoirs are owned by the municipalities; however, the state management agency retains control over the fisheries. There are between 1600 and 2000 ha of this type of reservoir in Kentucky; however, only about two thirds are suitable for reservoir ranching. The regulations permit only the stocking of paddlefish, once every ten years. Harvest gear is restricted to 127 mm (5 in) bar mesh gill nets preventing harvest of smaller fish for meat. In addition, the management agency provides no enforcement protection for the paddlefish and allows taking by archery fishing.

Despite these constraints, private individuals have contracted with municipalities and stocked over 800 ha (1976 acres) throughout Kentucky. The reservoirs range in size from 20 to 270 ha (50 to 667 acres) and were stocked at up to 50 paddlefish/ha (20 paddlefish/acre). A minimum stocking size of 150 g (0.33 lb) was selected to minimize mortality from predation. After three years, sampling has produced paddlefish up to 6 kg.

Researchers at Kentucky State University are sampling two of the largest stocked reservoirs to monitor for any changes that may occur in the reservoir or sport fishery that would indicate negative effects from the paddlefish stocking. To date, no negative effects have been reported. Based on anecdotal information, one municipality has observed a reduction in blue green algae from 2008 to 2010, significantly reducing their cost of adding an algaecide. The paddlefish themselves are also being monitored for survival, growth and progression to sexual maturity (≥ 8 years), when the females can be harvested for roe. The results of a state-wide survey mandated by the Kentucky Legislature showed strong public support for the concept of paddlefish ranching in the state’s large reservoirs. Reservoir ranching of paddlefish could become an economically viable alternative to current river fisheries for wild paddlefish that are being increasingly restricted to the point of closure. Current estimates show potential revenue of US$ 5,000/ha assuming 50% survival (12.5/ha) to maturity for females, 1.5 kg roe harvested/female and wholesale price (US $125/lb) for caviar.