Aquaculture

Aquaculture Systems

There are three basic types of systems and some aquaculture facilities will have variations of each.

1. Flow through systems - When there is an abundant and easy to harness supply of clean water, a concrete raceway or pond is constructed such that the constant flow of water creates a favorable place to raise fish. For cold water species, such as trout, the source of water will usually be from a spring or artesian well. In these systems the solid waste from the fish will settle to the bottom and with some management practices the solids are periodically removed by suction. Another methods of solids management is to leave the solids accumulate at the bottom of the pond for a season or more and then drain the pond to scrape out the solids. The solids can be disposed of by spreading on land or by dewatering and used as fertilizer. The operators of flow through systems should adopt best management practices to minimize the impact of the discharge water on the receiving water from carry over of fish waste, changing the water temperature or from chemicals used to treat the fish.

2. Pond Systems - A typical use of pond systems is in growing warm water species from fry to fingerlings. The ponds are initially filled with water and fertilized to create a natural growth of aquatic organisms to provide a natural food source for the fry. With low fish densities, they can grow for a whole season with natural aeration and some supplemental feeding. Higher densities of fish may require mechanical aeration, supplemental feeding, and a supplemental flow through water source.

One method of operation is to harvest the fingerling in the fall for transplanting into waters of the state or to another system to grow to food fish size. Ponds can also be used to grow fish to adult size for food fish of fee fishing. One method of management is to completely drain the pond to harvest the fish. During a complete draindown, the wastewater should be directed to a separate settling pond to remove stirred up fish wastes and other settleable solids prior to discharge to the receiving stream. Another harvest method is to seine the fish out with no drawdown or a partial drawdown.

3. Recirculating Systems - The advantage of recirculating systems is that a high density of fish can be kept at optimum temperatures by removing the fish waste and reusing the water. The rate of growth is usually faster and the system can be covered to protect the fish from predators. Most recirculating systems are in buildings raising warm water species like perch. An effective wastewater treatment system will usually include a settling tank followed by a biofilter. The biofilter provides a medium for aerobic bacteria to convert organic fish waste and ammonia into their cell mass and then it is removed as a settleable sludge. Some systems will include more treatment units such as air stripping, micro filtration and disinfection. The technology for effective, reliable and economic treatment systems to clean up the water for recycle continues to improve every year. Waste discharges include solid fish waste, sludge from the biofilter and a low percentage of water dumped each day to control pollutants that are dissolved in the tank water and not removed by the treatment system. The solids have nutrients beneficial to plants and should be used as fertilizer whenever possible.

Aquaculture Products

The aquaculture sector is always striving to supply what their customers want. These are Wisconsin's aquaculture products.

1. Food Fish - These fish are raised to adult size and sold live or ready to cook fillets. Trout and perch are the common species in Wisconsin. Some farmers add value to their product by delivering fresh fish to local restaurants, smoking their fish and retail sales at the farm.

2. Fee Fishing - Adult fish are raised in private ponds and the customers have the thrill of catching and keeping a fish for a certain fee, which is generally based on the size of the fish. Some farmers clean the fish and some even cook the fish as part of a picnic or bread and breakfast guest package.

3. Bait Fish - Minnows are hatched from eggs, raised in a pond and sold in bait shops to sport fishermen for bait. Some farmers use shallow seasonal ponds where minnow fry are stocked in the spring and harvested before winter. A few farmers supplement their sales by harvesting minnows and insect larvae from the wild. DNR and private farmers raising game fish for eventual stocking into the wild also purchase minnows as live feed.

4. Stocking - Fingerlings or larger fish are released to grow into catchable size sportfish. The market for stocking size fish includes registered fish farmers that want to enjoy unrestricted fishing in their own ponds. Lake associations, sport clubs and similar organizations purchase fish to stock their favorite lake even though it has public access and make receive some stocking from DNR. Lakes with no public access are not stocked by DNR, but the private landowners may purchase stockers. Stocking of any waters other than a registered fish farm require a stocking permit from DNR and a fish health certificate from DATCP. Fish Stocking Permit

Environmental Issues

Water Discharge

The raising of fish will generate excess water or waste that must eventually be discharged to surface waters or to land application. The volume of wastewater will depend on the type of system with flow though raceways generating the most discharge and recirculating systems the least. Fish waste is an organic pollutant measured as Biochemical Oxygen Demand (BOD) As BOD decomposes in receiving streams, it uses up the dissolved oxygen that wild fish and aquatic life depends on. Phosphorus and ammonia nitrogen are other pollutants in fish waste.

A Wisconsin Pollutant Discharge Elimination System (WPDES) permit regulates discharges into surface water or groundwater. A WPDES permit has concentration limitations for pollutants from fish waste, such as suspended solids, that are calculated to protect the water quality in the receiving stream.

The U.S. Environmental Protection Agency (EPA) effluent limits for aquaculture facilities discharging to surface water require a WPDES permit only if one of the following conditions is met.

1. Production of more than 20,000 LB/yr. of cold water species
2. Production of more than 100,000 LB/yr. of warm water species
3. Feeding more than 5000 LB of feed/month
4. The facility is defined as a significant source of pollution

Aquaculture systems are encouraged to adapt best management practices, such as collecting all settleable solids prior to discharge, to avoid being identified as condition 4. Discharge to streams classified as "exceptional" or "outstanding resource waters" should be avoided.

Exceptional and outstanding resource waters [PDF 99KB] are listed on the web. For more information about wastewater discharge see Getting Started in Aquaculture: Environment Concerns and Regulations [PDF 64KB].

Water Supply

Aquaculture is well suited to Wisconsin because of an abundance of clean water from surface waters and groundwater. Some existing facilities are fortunate to utilize a free flowing water supply from a spring or flowing artesian well. In many parts of Wisconsin the groundwater table is near the surface and cool clean water can be economically pumped to a fish pond. A high capacity well permit is required if the total pumping capacity of all the wells on the site exceeds 70 gallons per minute. There are few restrictions on the volume of groundwater that can be pumped. Currently the only restriction is that pumping from a high capacity well does not draw water away from any municipal well.

Water for fish raising can also be withdrawn from surface water, however some restrictions may apply. A basis legal restriction is that any withdrawal cannot interfere with the public interest in the navigable waters, the rights of the public or the rights of the downstream users. Construction of a dam or diversionary structure to accumulate water and draw it off to a fish pond may require a permit.

More information on surface water withdrawal is available.

Pond Construction

Many aquaculture projects start with the construction of a fish-rearing pond. It is very important to select a proper location for a pond so that the design will comply with any construction permit required and with an optimum location no permit will be required. Whenever possible, build ponds and structures in an upland area away from wetlands and existing waterways. These are the types of pond construction activities that will require a DNR "chapter 30 permit":

• "Unconnected" Ponds within 500 feet of a public navigable waterway
• Ponds with open or closed outlets to public navigable waters, even if the pond is greater than 500 feet from the waterway
• Ponds connected by an open navigable channel to an existing public navigable waterway, or any enlargement of any public navigable.
• Grading in excess of 10,000 square feet (1/4 acre) on the bank of a public navigable waterway.
• Construction of ponds in a wetlands. Generally construction of fish ponds in a wetland should be avoided because the high level of nutrients and resulting excessive weed growth are detriments to rearing fish. Wetland protection regulations prohibit fish pond construction in a high quality wetland. Construction of wetland ponds can only be approved if the landowner can show that there are no other alternatives and the quality of the wetland will not be harmed.

For more information about pond construction see the Waterway and Wetland Permits page.

Raising Fish in Natural Water Bodies

Sometimes fish farmers want to convert a natural pond on their property into a registered fish farm. However Wisconsin's constitution specifies that natural ponds are waters of the state and thus cannot always be used for private aquaculture. State statutes and codes limit the expansion of aquaculture into public waters to only freeze out ponds. These are shallow ponds, generally less than 5 feet deep that freeze-out 2 out of 5 years. A Natural Water Body Permit (also called a NR 16 permit) is required to use a natural waterbody for a new fish farm. Another requirement for a Natural Water Body permit is that the farmer must lease or own all the land around the pond so that no public access is provided. If a natural waterbody doesn't meet these statutory requirements, it cannot be legally operated as a fish farm. A deeper pond can be stocked and used as a private fishing pond, but a DNR stocking permit is required, and all fishing activities must comply with all state fishing regulations including seasons, minimum sizes, bag limits and a fishing license is required. For more information see Environmental Permits for Aquaculture - Natural Water Bodies page.

Importation of Native and Non-Native Species

Regulations require an annual import permit to bring live fish or fish eggs into Wisconsin for stocking into state waters, use as bait, holding or hatching on a fish farm, or sale or distribution for any of those purposes. A health certificate issued for that shipment or some other evidence of the fish health must accompany each import shipment. The Department of Agriculture Trade and Consumer Protection (DATCP) administers the import permits and health regulations [exit DNR].

Applications to DATCP to import a non-native species are referred to DNR for review and if DNR concurs, DATCP will issue an import permit. This is necessary because the intentional or accidental release of non-native species that compete for food and habitat with native species may have a detrimental effect on native populations.

Although some of the more popular farmed species, rainbow trout, brown trout, Atlantic salmon, coho salmon and Chinook salmon, are not on the native species list, they are established in Wisconsin and their importation is routinely approved. DNR intends to promulgate an official list of acceptable non-native species because is will be more efficient than reviewing each nonnative import request on a case by case basis. This list of native fish [PDF 18KB] will help you see which fish are native, transient, or established. Those listed as native can be imported with only a DATCP import permit.

Wild Bait Harvesting

A bait dealer's license is required to take or remove bait fish from the wild if offered for sale in this state. Anglers with a fishing license may harvest up to 600 minnows for personal sport fishing. The regulations for wild bait harvesting are designed to prevent over-harvesting of baitfish where they are a food source for a natural fish population.

Fish Farm Registration

If you operate a fish farm in Wisconsin, you need to register with the Department of Agriculture, Trade and Consumer Protection [exit DNR] and renew your registration annually. You are operating a fish farm if you hatch or hold fish for:

• Sale, fee fishing, bait or fertilizer
• Release in lakes or streams
• Sale as human food or animal feed
• Education, demonstration, or research