Addressing Concerns for Water Quality Impacts
from Large-Scale Great Lakes Aquaculture

Based on a Roundtable
Co-hosted by the Habitat Advisory Board of the Great Lakes Fishery Commission
the Great Lakes Water Quality Board of the International Joint Commission

August, 1999

Appendix 12

A Farmer's Perspective

by Gord Cole
Aqua-Cage Fisheries

Comments on Regulations and a Case Study of an Environmentally Friendly Farm


Aqua-Cage Fisheries

Aqua-Cage Fisheries Ltd. has been operating a cage culture fish farm in Georgian Bay since 1982. This was probably the first use of Norwegian-Style cage culture in freshwater anywhere in the world. It is possibly the oldest continuously operated cage farm anywhere in North America. This farm demonstrates the sustainability and minimal environmental impact of a typical fish farm. Aqua-Cage is an environmentally pro-active company, as are most Great Lakes cage farmers. Large amounts of scarce time and money are spent on pro-active environmental projects. The few exceptions, farmers who are not responsible, are why government regulations are required. Appropriate regulations are those which effectively prevent undesirable impacts, no more and no less.

Aqua-Cage has been operating in the same location since 1983 (a different location was used in 1982). There have been no public complaints. The farm consists of 26 cages each of which is 280 m2 or 370 m2. Five or six cages hold young fish and the rest have fish which will be sold that year. Fingerlings are purchased from a commercial hatchery and grown for 14-15 months. Market size is 1 kg plus. The grow-out period includes low growth in November and almost no growth December through April. Biomass peaks in the fall and declines about 80% over winter as fish are sold. Other cage sites in Georgian Bay have similar production cycles.

Aqua-Cage actively works to minimize environmental impacts. The two major components of the environmental program are fallowing and low pollution feed.


Aqua-Cage moves their cages seasonally. The fish are kept in the harbour from mid fall until late spring. The harbour is 9-10 meters deep with a good current. The cages in the harbour are protected from ice damage and remain easily accessible during the winter harvest. Fish and cages are moved into a more open location during the summer. This basin is over 3 km3 in volume and the water is estimated to exchange several times a year. The basin has a maximum depth of about 160 meters, with about 60 meters of water where the nets are moored in the summer.

Each location fallows for part of the year. Sediments that accumulate under the cages during the feeding period, dissipate during the fallowing period, preventing year to year accumulation. Moving the cages twice a year is time consuming and expensive. It is worthwhile for Aqua-Cage because it allows much greater fish production with very low environmental impacts. Seasonal fallowing is not appropriate for most farms, but other fallowing strategies may be used. It should be noted that farms require two or more sites to fallow.


Proper use of low pollution feed is the second critical component in minimizing environmental impacts. Aqua-Cage has been using high energy, low pollution feeds since 1983. Low pollution feed was not commercially available in 1983 so a custom formula was developed with Drs. Hilton and Slinger from the University of Guelph. The feed formula has changed almost yearly as new information becomes available and new manufacturing processes are developed by Martin Mills. Today low pollution feeds are available from all feed companies and almost universally used.

Early low pollution feeds simply minimized the indigestible portion of the diet, reducing solid waste, biochemical oxygen demand, and phosphorus. The second step in the evolution of low pollution feed was reducing phosphorus to the minimum level required for fish health and growth. The third development was new technology that allowed high levels of fat to be included. This increased the energy density of the feed which reduced the amount of feed needed to grow a unit of fish. Optimizing the protein to fat ratio took several years.

Recently it has become apparent that biochemical oxygen demand is the critical environmental waste product from cages. Current research involves further reductions of biochemical oxygen demand. Calculations indicate that biochemical oxygen demand, solid waste, and phosphorus produced per unit of fish have all been reduced 70-85% over the last 20 years through improved diets.

The other feed related source of waste is uneaten feed. Feed is expensive, accounting for 40% of production costs. Farmers have enormous economic incentive to waste as little as possible. New technologies, such as underwater video cameras, are further reducing feed waste.

Other Environmental Initiatives

Aqua-Cage has tried to be environmentally friendly when the opportunity arises. Two stroke out-board engines have been replaced by four stroke engines. "Green" hydraulic fluids are used. Most feed is purchased in bulk, eliminating tens of thousands of plastic bags per year. Only environmentally-friendly cleaners are used.

Other cage farms have their own environmental programs. Most feed used is a low pollution type. One farm has been working with a local University on biochemical oxygen demand and COD research. Another farm has installed a system which draws water from the bottom, aerates it and returns it to the bottom. Several farms are cooperating with Dr. C. Young Cho in developing waste production models. Most cage farmers think of themselves as pro-active environmentalists, stewards of the resource. Unfortunately the rare "bad apple" gets the publicity.

Sample Water Quality Results

Aqua-Cage hires Eco-North laboratories to take water samples around the farm. Phosphorus is consistently below 0.01 mg/L. Suspended solids are generally 0.25-1.0 mg/L. The highest suspended solids level ever recorded is 2 mg/L. Dissolved oxygen is generally 90% saturation or more, and always above 80% saturation. Two sample months are shown in Tables 1 and 2.

Table 1. Phosphorus and suspended solids data collected from various locations at Aqua-Cage Ltd. aquaculture farm.

Date Site Location Total Phosphorus (mg/L) Total Suspended Solids (mg/L)
July 9 1998 Bay East <0.01 <0.20
July 9 1998 Bay Centre <0.01 <0.20
July 9 1998 Bay West <0.01 <0.25
July 9 1998 Farm <0.01 <0.50
Sept. 17 1998 Bay East <0.01 0.75
Sept. 17 1998 Bay Centre <0.01 2
Sept. 17 1998 Bay West <0.01 0.25
Sept. 17 1998 Harbour East <0.01 1
Sept. 17 1998 Harbour Control <0.01 1
Sept. 17 1998 Harbour West <0.01 1

Table 2. Temperature and dissolved oxygen data collected on October 13, 1998 from various locations around Aqua-Cage Ltd. aquaculture farm.

Location Depth of Sample (m) Temperature (° C) Dissolved Oxygen (mg/L)
Bay West 0 15.6 12.2
Bay West 15 10 14.4
Bay Centre 0 14.1 11.9
Bay Centre 15 14.2 10.2
Bay East 0 13.9 10.4
Bay East 15 14.2 10
West Cage 0 14.1 9.9
West Cage 8 14.3 8.9
Centre-Surrounded by cages 0 14.2 9.1
Centre 8 14.3 9.2
Control-Stanley Island 0 14.3 10.4
Control 15 14.3 10
Control- 3 mile point 15 14.3 10
Harbour West - downstream 0 14.1 9.4
Harbour West 8 14.1 8.9

Summary of Environmental Concerns Regarding Fish Farming

Water Quality

Fish farms add feces and small quantities of uneaten feed into the water. Zero tolerance pollutants, such as heavy metals, carcinogens, human pathogens, endocrine analogs, radioactivity, etc. are not produced. Potential negative impacts are limited to local eutrophication and reduction of local dissolved oxygen, especially in the hypolimnion. These impacts will only occur if these discharges are present in excessive amounts. Problems may be avoided by limiting inputs which in turn limits discharges. Limiting the feed used at a site is a very simple and effective way to limit input. The feed quota for a site will depend on the sites estimated carrying capacity. The quota can be adjusted up or down based on water testing results. An objective formula for this adjustment should be used rather than discretionary decisions. Accurately measuring a site's carrying capacity is impossible, so keep it simple, cheap, quick and conservative. Fine tune later with the quota adjustments. This system minimizes waste by providing the farmer with an incentive to grow the most fish possible on the feed quota.

Regulatory agencies should not be concerned with the internal workings of the farm, other than feed use, and water quality. The number of fish, size of fish, feed conversion, fish movements, etc. are irrelevant to the regulator. Requiring this information is an unreasonable intrusion.

Two other water quality questions that have arisen elsewhere concern therapeutant residues and antifouling compounds for nets. Studies done elsewhere indicate that therapeutants disappear quickly from the waste under farms, if they are ever present. Therapeutant use in Ontario is very low so it should not be a problem. Testing at several Ontario fish farms found no detectable therapeutant residues. Antifouling compounds are not used in Ontario on nets, to the best of the author's knowledge.

Water quality testing must be limited to parameters of concern, specifically phosphorus, dissolved oxygen, and suspended solids. Testing should be carried out periodically during the ice-free feeding period. Every 6-8 weeks is adequate providing the period following turnover is tested. Excessive testing is unwarranted and places an unreasonable financial burden on the farm. Testing must not become a farm funded government research project.

Introduction of Exotic Species

Fish farms should never be responsible for introduction of new species into any waters. Fisheries managers, baitfish, ornamental fish, and transportation cause more than enough introductions.

Fish should only be grown in waters where the species already exists in contiguous waters, or grown in a close system. The exception to this rule is where the introduction of the species would be considered desirable. Reintroducing a species into waters it previously occupied would be one example of a desirable introduction (e.g., sturgeon into many Ontario waters). Rainbow trout are obviously not a concern in the Great Lakes.

Genetic Dilutions of Native Fish

The gene pool of some populations of native fish should be protected where the original heritage gene pool still exists. The original gene pool is often lost as a result of heavy selective harvest, large scale stocking of the same species (especially but not exclusively from different stocks), habitat loss, remnant population isolation, government stocking, etc. Where a heritage gene pool exists, fish of the same species should not be cultured in the same waters unless they are kept in a closed system. Note that Ontario Ministry of Natural Resources has identified specific types of populations that need protecting, such as some sympatric and allopatric populations.

Protecting heritage gene pools also involves controlling all modifiers of the gene pool, not just fish farming. This includes selective harvest, habitat loss, government stocking, etc. Genetic concerns do not apply to introduced species. This is particularly true of rainbow trout since the Ontario Ministry of Natural Resources purchased its trout broodstock from the same hatchery that supplies farms with fingerlings.


Disease transmission from commercially farmed food fish to wild fish populations has never been documented, as far as this author knows. Ontario fish farms have an excellent fish health record. Some hatcheries have been certified specific pathogen free for about 25 years. Fish farms are highly unlikely to introduce new pathogens into the province because live fish or eggs are rarely imported. The few importations that do occur come from specific pathogen free sources in the Great Lakes basin (Quebec).

Within the province, farms are very careful to purchase only healthy fish. Ontario farmers have excellent professional fish health services provided by the Ontario Veterinarian College in Guelph which helps keep our fish healthy. The real risk of introducing diseases lies with other live fish movements. Farmers feel that management agencies are placing farms and wild fish at considerable risk by not regulating these other fish transfers, especially baitfish, but also ornamental and other food fish. Government programs are also often risky.

Regulatory Regime

Regulatory agencies, especially fisheries agencies, have consistently demonstrated an inability to deal with fish farms in a reasonable fashion, probably due to a total lack of understanding of what a fish farm is. Fish farming is NOT a fisheries activity, it is farming, feed lots producing meat for human consumption. Fisheries biologists have no more understanding of fish farming than wildlife biologists understand beef farming. Farmers of fish should not be dealing with fisheries biologists any more than a beef farmer should require permits from a wildlife biologist. Farmed fish are not a common property resource, they are private property and must not be subject to the whims of fisheries managers.

Most fisheries managers see little or no benefit to fish farming, so when a risk-benefit analysis is done even a very low risk is considered unacceptable because the perceived benefit is negligible. Much greater risks associated with fisheries activities are considered reasonable because the perceived benefit, from a fisheries point of view, is much greater. A more objective observer would rate the farming benefits much higher, and the fisheries benefits much lower, than would a fisheries manager. Bait fish is a perfect example. Anglers releasing baitfish have caused hundreds, probably thousands of undesirable introductions in Ontario lakes (rock bass, perch, suckers, etc.) and spread parasites and pathogens. This proven, serious, and virtually uncontrolled problem is tolerated because it is part of sport fishing. Fish farming has not caused introductions or spread disease and yet is highly regulated and only semi-tolerated because it is not sport fishing. Note that the absence of the problems from farmed fish preceded the regulations. Fisheries agencies act as if their sole function is to provide recreational angling opportunities, not balanced resource management.

People seem unaware that fish farms may have beneficial effects. They always increase local fish populations, creating angling opportunities. Interestingly, the most successful (perhaps the only successful) lake trout rehabilitation in the Great Lakes, outside Lake Superior, has occurred in the waters around Aqua-Cage Fisheries during the time Aqua-Cage has been operating. This may be a result of habitat improvement caused by the farm.

Fish farming is more regulated than most activities. A cage farm in Ontario requires the following:

  1. fish culture license from Ontario Ministry of Natural Resources;
  2. water lot tenure from Ontario Ministry of Natural Resources;
  3. exemption to moor in navigable waters from Federal Department of Transport;
  4. various licenses and permits from local governments which may include fish culture and environmental permits from First Nations, building permits, zoning variances, etc. (generally local permits require public hearings);
  5. Hazard Analysis Critical Control Point (HACCP) standards through the independent "Healthy Salmon Program"; and
  6. regulation of therapeutant and chemical use (prescriptions or permits may be required).

Farms previously required Certificate of Approval's from the Ontario Ministry of Environment. This requirement was discontinued with no input from industry. Ontario Ministry of Environment subsequently refused to set standards or become involved with regulating cage farms, despite years of lobbying by industry and the Ontario Ministry of Agriculture and Food. Environmental standards are now included in the Ontario Ministry of Natural Resources fish culture license.

Permits were previously required to ship live fish. This has been replaced by requiring normal commercial documentation (i.e., bill of lading).

The inputs and outputs of the farm are also highly regulated. Fingerlings are purchased from hatcheries which have the same requirements as a cage farm plus the Ontario Ministry of Environment Certificate of Approval and often a Department of Fisheries and Oceans Fish Health Certificate. Processing plants are subject to federal and provincial inspection. They document for both Quality Management Programs (QMP) and increasingly, HACCP. Feed manufacturing also involves tight regulatory controls.

Big brother watches from cradle to grave.

Reasonable regulations must place fish farming in the context of the real world, which is not a pristine place. Virtually all of the dominant coldwater species in the Great Lakes are introduced, from zooplankton through forage fish to the top predators. There is no natural coldwater ecosystem to preserve so don't pretend there is. Managers should be considering the needs of all users of the resource, not just anglers, and the benefits to society as a whole. Objectively, fish farming can be one of the most environmentally friendly activities we humans can undertake.

Regulations should be effective in dealing with an issue. This means the regulations must apply to all potential sources of the problem, not one sector. The potential negative impacts of fish farming are concerned with fish waste and the movement of live fish. Fish pathogens, as an example, may be spread by the movement of any live fish. Note that fish pathogens will affect most species. Baitfish can carry salmon diseases. Introduction of pathogens has been documented via baitfish, government stocking, and transportation (shipping, canals, etc.). Pathogens spreading from commercially farmed food fish to wild fish has not been documented. Regulating only the low risk vector (i.e., farms), and ignoring high risk vectors is ineffective and absurd, but that is the situation under both Ontario regulations and Canadian Federal regulations. Regulate by problem not by sector. Special rules for fish farms are NOT required.

A wise man said that dairy farms operating under the same constraints as fish farms would be required to milk moose.