Strictly speaking, aquaculture systems – fish farms – have operated continuously in Michigan since 1873 when the Michigan Fish Commission, predecessor to the DNR Fisheries Division, established the state hatchery program. Replenishing fish populations lost to pollution and habitat destruction was the primary function.
For the most part, the Michigan aquaculture industry has operated quietly and efficiently and until recently, with no real cause for concern. The industry has grown slowly and the focus has broadened somewhat to include baitfish growers raising minnows as well as private and state fish farms that raise fish for human consumption. Capacity and revenue have grown slowly. Environmental impact has been localized and short term thanks to remedial measures taken when needed. On the commercial side, it remains a minor business producing annual revenue of approximately $5,000,000
However, in the last few years debate on this topic has gained in volume with a corresponding increase in awareness. As is often the case, this argument boils down to familiar and opposing points of view: environmental concern versus economic benefit. The central issues are those of size and impact: how big does the business have to be in terms of revenue to be sustainable and how much negative impact will an expanded operation have on the environment?
Given current technology, aquaculture systems fall into two basic classifications depending upon the level of two risk factors: the negative impact on the environment from waste products and the potential for caged fish to escape containment.
As all living creatures do, fish produce waste when they defecate, tons of waste potentially, rich in phosphorous, a known source of concern for large bodies of fresh water like the Great lakes. Caged fish also pose a serious threat of disease to wild fish populations and of genetic contamination if they escape.
High Risk
Any methodology that allows free and unregulated exchange between the farm and the surrounding environment presents a high risk of contamination.
- Open net-pen systems. Most authorities consider open net-pens or cages a very high-risk aquaculture methodology. Imagine a large floating square in the water with nets suspended from each side of the square and anchored to the bottom. Millions of fish are contained and fed within the pen. Water containing high concentrations of waste and parasites flows freely into the surrounding environment. Fish escape is highly likely.
- Operators divert flowing water from natural streams or a well – typically used for raising rainbow trout. Due to the proximity to natural habitat, filters and barriers must be in place to treat wastewater and prevent escapes. If not, raceways present a high environmental risk
Low Risk
Closed systems or closed containment farming methods use a barrier to control the exchange between farms and the natural environment. This significantly reduces pollution, fish escapes, negative wildlife interactions and parasite and disease transfer from farms to marine and freshwater ecosystems. Wastewater is filtered, treated and often recirculated. Examples include:
- Recirculation Systems. These systems treat and recirculate water. It does not mix with natural water sources, which mitigates pollution, parasite transfer and fish escapes.
- Ponds – semi or fully enclosed bodies of water. Pond farms present a low risk only if they refrain from discharging untreated wastewater, which pollutes the surrounding environment. Discharged waste must be treated and filtered.
As you can imagine it costs money to reduce risks. The most cost effective methods to produce large masses of marketable fish involve open net pen systems or raceways without systems to filter and treat wastewater. These are the very ones that present the highest level of threat to the environment.
In Lansing, the issue has generated a great deal of debate and pending legislation on both sides in the Michigan Senate and House of Representatives. See below for a summary:
Michigan House of Representatives:
- John Bumstead R., Newaygo. House Bill number 5255 would ban net pens in Michigan Great Lakes Waters and connecting rivers.
- Ed McBroom R., Escanaba and Triston Cole R., Mancelona. House Bills 5166 – 5168: a package of bills that would allow aquaculture pens and consolidate permitting
Michigan Senate
- Rick Jones R., Grand Ledge. Senate Bill number 5266 would ban fish farming in flow through systems in the Great Lakes and all tributaries
- Darwin Booher, R., Evart. Three bills that would allow fish pens in Michigan restricted to 10 operations in the first five years