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
and
the Great Lakes Water Quality Board of the International Joint Commission

August, 1999


EXECUTIVE SUMMARY

Aquaculture is an emerging issue in the Great Lakes basin caused by an increased demand for freshwater fishes and by concern over expansion of a relatively new industry. Globally, the current demand for seafood has increased to the point where the United Nations estimates that nearly one-quarter of the protein in human diets is derived from seafood, of which 21% of the world consumption of seafood comes from aquaculture. With the rapid expansion of aquaculture there have been concerns expressed about the impacts the industry may have on water quality and biota, as well as economic and social benefits.

As part of the Great Lakes Fishery Commission charge to assess habitat alterations and recommend mitigative strategies to address concerns for aquaculture in the Great Lakes basin, a roundtable discussion of water quality impacts of Great Lakes aquaculture was held on January 27-28, 1999 in collaboration with the Great Lakes Water Quality Board of the International Joint Commission. This report only addresses water quality impacts of large-scale Great Lakes aquaculture. Water quality impacts due to hatchery operations have been documented in Michigan's Big Platte Lake (i.e., elevated phosphorus levels, increased primary productivity, reduced water transparency). In addition, water quality impacts due to caged aquaculture have been measured in Minnesota mine pit lakes (i.e., approximately an order of magnitude increase in water column phosphorus, nitrogen, and chlorophyll levels, and increased attached algal growth) and in one case in Ontario on the North Channel and Georgian Bay of Lake Huron (i.e., elevated phosphorus levels, reduced water transparency, algal blooms, and dissolved oxygen depletion over 250 ha). Industry representatives provided information that other operations in Georgian Bay have been well managed and have not resulted in any significant water quality problems. It was generally felt among roundtable participants that water quality problems can be substantially prevented with better assessment, siting, prediction of carrying capacity, and management of food and fish.

Caged aquaculture operations in the Great Lakes are currently limited by available technology and suitable sites. Neither caged nor land-based aquaculture is expected to grow substantially. The aquaculture industry is interested in achieving economically-viable and environmentally-sustainable operations. Both the aquaculture industry and governments want to limit water quality and habitat impacts.

One promising analytical tool, sponsored by the Great Lakes Fishery Commission, is being developed to help prevent water quality impacts from aquaculture and prevent introductions of exotic species. This decision support system titled "Environmental Assessment Tool for Private Aquaculture in the Great Lakes Basin" is being developed by the University of Minnesota. This user-friendly, computer-based system is designed to help direct impact assessments and guide risk management decisions regarding private aquaculture operations.

Based on a review of the information and discussions from the roundtable, and the extended abstracts presented in this report, the roundtable steering committee has made the following recommendations:

To governments it is recommended that:

To the Great Lakes Fishery Commission and the International Joint Commission it is recommended that they:

To government agencies, universities, and the Commissions it is recommended that the following research needs be addressed:

To the aquaculture industry it is recommended that: