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 3

Great Lakes Aquaculture and Water Quality
by Ian Smith 1
Ontario Ministry of the Environment, Water Policy Branch, 40 St. Clair Ave. W., 12 Fl., Toronto, ON M4V 1M2 (416)327-7714, FAX (416)327-9187

What are the issues?

The Habitat Advisory Board of the Great Lakes Fishery Commission and the Great Lakes Water Quality Board of the International Joint Commission have jointly organized this roundtable to review the issue of aquaculture in the Great Lakes with respect to water quality and quantity. The Boards have an advisory role on ecosystem quality which they exercise by offering advice to governments and stakeholders alike. The potential impacts of cage culture and shore-based aquaculture in the Great Lakes basin upon physical, chemical, and biological attributes of aquatic habitat and ecosystem health are what drew the Boards to consider this issue. During the organization of the roundtable it became clear that the issues surrounding cage culture were particularly complex. Some of the issues for cage culture were similar to those for land-based operations, but others were unique, largely because of the physical setting that typically characterizes cage cultures.

The question of whether cage culture is a sustainable industry without environmental impacts has been asked in many regions. Controversy abounds on two salt-water coasts with respect to economic viability and habitat impacts - in the Great Lakes, water quality impacts have recently emerged as a consideration. Representations by industry representatives suggest that behind the hype of interest groups and controversy surrounding how governments regulate and manage this industry exists a willingness of the industry to ensure that negative impacts are minimized. This roundtable was organized to provide the two boards access to the experts from both sides of the issue so that recommendations to their parent organizations can be made. An additional consideration was to offer a forum where experts from both sides of the border (and issue) could share insights and possibly solutions.

When traditional hatchery and aquaculture facilities are sited on land, the impacts on aquatic habitat, water quality and water quantity are relatively simple to assess and manage. Nutrient impacts on receiving water quality, groundwater drawdowns that reflect unsustainable withdrawals, and observation of escaped fish all represent measurable impacts that can be managed simply. What makes the issues surrounding cage cultures so much more complex is the more "open" environment in which they operate. The waters where cage operations are typically placed are large, open and deep, making nutrient impacts difficult to monitor without expensive equipment or surveys. How much water a cage culture "takes" is unknown, but the production of fish/year can be used as a measure of "water use" and hence a means of comparison. Escaped fish from cages is typically the most easily observed impact, characterized by fleets of fishing boats drawn up next to the border delineating the operation.

The challenge for the governments and industry in ensuring the cage culture industry is economically-viable and environmentally-sustainable comes from the peculiar nature of the operation itself. The waters of the Great Lakes are "public" and hence cages are using a "common resource" for fish production. The issues around siting cages, cage design, location of shore facilities, etc. can become significant public issues during consultation prior to licensing. The limits on the growth of traditional land-based units caused by land prices and taxation, or restrictions on water extraction and discharges for example, make the development of cage culture operations a potential area of growth, which could exacerbate public concerns, and which will challenge the governments licensing and permitting such facilities. The existence of land-based aquaculture may be complicated in the future by the increased pressure upon both groundwater and surface water supplies. Global warming, El Nino and other causes for water shortages will undoubtably put pressure upon the use of water to grow fish. Applications for permission to grow new species of fish represent an additional area of consideration for regulators, given the "open" nature of the Great Lakes basin and the demonstration of exotic species impacts virtually ad-nauseam in the past.

What is the workshop answering?

The plethora of positions and issues has led the two boards to construct this roundtable in such a way as to answer, if possible, the following questions, with a view towards identifying the most significant issues which should be raised with the Great Lakes governments and other interested parties:

  1. What are the known water quality impacts of Great Lakes aquaculture? What are the potential long-term impacts?

Known impacts include chemical (habitat) impacts on productivity of receiving waters (eutrophication) resulting in enhanced biological productivity and occasionally reduced dissolved oxygen. Solids discharged from the facilities can foul adjacent physical habitat and reduce oxygen content. Water clarity can be reduced and the occasional dead fish can produce a disagreeable aesthetic situation. Over the longer term, impacts on ecosystem health of introduced species that escape, disease introduction and exacerbation, and the development of antibiotic resistant disease organisms are potential biological concerns. On the water quantity side, groundwater supplies and multiple use for increasingly scarce surface water supplies are likely areas of conflict. User conflicts over the allocation of sites for cage cultures, given the common nature of the affected resource, are not a "quality" issue, but will continue to focus public scrutiny on the cage culture industry.

  1. What can be done to prevent or abate water quality impacts due to aquaculture? Is there adequate protection under the current law? What are the various roles of government and industry?

Land-based aquaculture facilities typically have to meet regulations or rules for their discharge so that negative impacts are minimized. Given the ease in monitoring these facilities and their impacts, such protection is likely to be adequate for water quality, but may have to be re-evaluated with respect to water quantity if water shortages and a reduced water budget in the Great Lakes basin becomes issues. Regulations or rules can specify discharge limits as a simple means of limiting negative impacts. For cage culture facilities, the siting and design of facilities, and their management, are ways of minimizing water quality impacts, including practices such as cage rotation, variable feeding regimes, or low density rearing. The principle concern for governments, in pursuit of their mandate to ensure impacts are minimized, is that they do not traditionally have the legal ability to mandate "husbandry" practices, but can only manage "discharges". Ensuring that adequate protection is maintained must clearly make a link between husbandry and "discharges" through either monitoring or modeling. The industry and the governments both have a role in ensuring impacts are minimized, one through creative husbandry and the other through flexible rules and regulations.

  1. Can governments (or the industry) ensure "no net loss" of physical and chemical habitat from new Great Lakes cage cultures? What does the "precautionary approach" mean for the industry?

It is generally accepted that incremental habitat (physical, chemical, and biological) loss represents a real threat to the health of the Great Lakes aquatic ecosystem. The real gap in knowledge to predict the impacts of seemingly minor habitat alterations upon productivity, diversity, adaptability, and even location of native fauna remains a singularly troubling phenomenon. One way to counter this absence of predictiveness is to "try it" and monitor changes, fine-tuning facilities and practices until no detectable impact is perceived. This approach however is costly in requiring regular monitoring and that the farm manager must be responsive to making changes so as to eliminate demonstrated impacts. Another is to develop and fine-tune predictive models that can be calibrated to consider current, feed rates, depths, bottom characteristics, ecosystem sensitivity, and other factors so that less intensive monitoring is necessary. Another consideration is the use of the "precautionary" approach, suggesting that in the absence of robust science, an extremely cautious approach to developing new facilities and changing husbandry or production at existing facilities be taken. The introduction of new species and management of diseased populations are two areas with potentially profound long-term impacts where the precautionary approach may be prudent. Physical and chemical impacts from feed and feces are areas where a more iterative approach may be useful.

  1. What are the priority research needs?

Governments are typically a significant contributor of the science to support management and hence the economic viability and sustainability of the resource being developed. In the case of the Great Lakes much can be learned from the experiences and research undertaken to support coastal cage operations in salt water. Areas that may be valid for research include the threat to wild fish posed by disease infecting caged or land-based operations, and the proper and prudent use of antibiotics to ensure disease resistence is not promoted. Modeling to facilitate siting and licensing seems a reasonable area for research, in order to predict impacts before they must be demonstrated if the iterative approach to siting is chosen. Given that the precautionary approach would suggest limiting new development until better certainty is obtained, the development of predictive Great Lakes models based upon monitoring and analysis of existing facilities would seem an area where the industry can offer support and cooperation, so that the onus does not rest solely upon the Governments.

  1. What monitoring strategies are needed and are in place?

Just what is the appropriate and necessary level of monitoring for aquaculture operations? Existing facilities may be grandfathered with respect to their operations, but given the interest in incremental loss and increasing pressure upon the aquatic resource, monitoring and compilation of the results of this monitoring in support of modeling would appear reasonable. For a new facility, whether cage or land-based, intensive monitoring until the facility becomes established and the ecosystem is in balance would also appear reasonable. But what to monitor, how often, and by who are the questions often asked. As stream beds and lake beds in the Great Lakes basin are normally a common resource, is there any onus on "the people" to ensure ecosystem health is regularly assessed? If the operator bears the entire responsibility, how is the monitoring undertaken, by agreement or by law? Is their sufficient food safety inspection procedures in place, as well as disease surveillance monitoring taking place? How is the level of escapement tracked and assessed? Finally, how accessible to the public and interested stakeholders is the monitoring information, particularly where a public and common resource is being assessed and possibly affected? Can the industry and/or governments provide a report card on the status of the environment upon which the industry is based?

What happens next?

The workshop summary will include the perspective and response of the attendees to the above noted questions. The two boards will review the workshop outcome and make recommendations to their parent agencies as they deem appropriate. Both boards are interested in the existing and potential water quality impacts of land-based and cage culture operations including nutrients and solids, and in the considerations being given to water (groundwater) use and quantity by land-based facilities, but they are most interested in the ability of the industry and the governments to manage aquaculture in a sustainable manner. It is likely that the governance of the industry by all levels of government, and the role of farm managers and industry associations, will receive the bulk of the boards attention. Both boards note with interest the operation of cage cultures by Tribes and First Nations, and the special challenges posed in this area of governance.

As the full impacts of reduced nutrient loadings to the open waters of the Great Lakes become visible through reduced wild fish production, due to successful management of farming practices and detergents, and the altered availability of primary productivity resulting from zebra mussel invasions, aquaculture has the potential to replace the traditional net fishery in supplying protein. However, it cannot do so at the expense of the health of the aquatic environment. In this context it is likely that the boards will request of the governments that some "common floor" in the area of policy and implementation be established in their oversight of this industry, given that the Great Lakes are a precious and shared resource, and that water quality and quantity are essential for the sustainability of the aquaculture industry.

1 This article was prepared on behalf of the Habitat Advisory Board of the Great Lakes Fishery Commission, and does not represent the perspective or position of the Ontario Ministry of the Environment.