Aquaculture in Georgian Bay – Water Quality and Environmental Monitoring
Contents |
Background
In 2003, two applicants requested a review under the EBR, citing numerous concerns about the Ontario government’s policies and regulations related to cage aquaculture in Georgian Bay public waters. The applicants included study results that suggest organic and nutrient enrichment are contributing to recent changes in water quality in Georgian Bay. They are concerned that increasing development, aquaculture and dredging activities in the area are contributing to the decline in water quality. The Ministry of the Environment agreed to undertake the review.
| What is cage aquaculture? |
|---|
| Cage aquaculture is a method of fish farming that involves growing fish (usually rainbow trout in Ontario) in cages that are suspended in a waterbody. Water flows through the cages bringing oxygen and carrying away wastes such as fish feces, uneaten food and medications. Wastes are also deposited on the bed of the waterbody beneath and downstream of the cages. This contrasts with land-based aquaculture where fish are raised in ponds or tanks and wastewater must be treated before it is discharged. |
The applicants noted that the eastern shoreline of Georgian Bay is primarily used for recreational activities, as a source of drinking water and as a receiver of domestic sewage. Georgian Bay has naturally low concentrations of nitrates, phosphates and other plant nutrients.
In 2003, there were approximately 190 private fish farms in Ontario, producing an estimated 4,550 tonnes of rainbow trout. About 80 per cent of rainbow trout production came from cage operations. Under subsection 47(1) of the Fish & Wildlife Conservation Act (FWCA), fish farm operators must have an aquaculture license from the Ministry of Natural Resources, which is valid for a five-year term. Operators must comply with the Environmental Protection Act, Ontario Water Resources Act (OWRA), federal Fisheries Act, and with the water protection measures defined in their FWCA license. Cage operators are not required to obtain any approvals under the OWRA. Since the Ministry of Natural Resources is responsible for cage aquaculture licenses, MOE can investigate water quality concerns only if there is a suspected violation of the OWRA.
Although MNR approved 10 policies on various aspects of aquaculture in 2004, a specific policy for cage aquaculture in the Great Lakes has not yet been developed. (For additional information about these policies and procedures, refer to pages 182-186.)
Several MOE policies are relevant to water and sediment quality under and around cage aquaculture operations, including the following:
- The minimum acceptable level for dissolved oxygen (DO) in water to protect organisms ranges from 5 to 8 mg/L, depending on the water temperature, according to the 1999 Provincial Water Quality Objectives (PWQO).
- The interim PWQO level (an interim PWQO is defined when there is insufficient toxicological information available to set a PWQO) for Total Phosphorus (TP) in water to protect against aesthetic deterioration, including algal blooms, is 10 µg/L or less if the background TP is naturally lower.
- The level of TP in sediment that will result in a detrimental effect to the majority of benthic (bottom-dwelling invertebrates such as dragonfly larvae) species is defined in the 1993 Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario.
- A general PWQO requires that all waters remain free of substances that can form objectionable deposits or can produce “adverse physiological or behavioural responses in humans, animals or plants.”
- A guideline in the 1994 Water Management document states “water quality shall be maintained at or above” the PWQO, “although some lowering of water quality is permissible.”
MOE documented its expectations for water and sediment quality monitoring conditions
in cage aquaculture licenses in its “Recommendations for Operational Water Quality
Monitoring at Cage Culture Aquaculture Operations, Final Draft, 2001,” which MOE
provided to MNR for implementation. MOE recommended that sediment sampling
be done one year prior to an existing aquaculture license’s being renewed, and that
an operator be required to submit an abatement plan if the median concentration of
TP in water is found to be greater than or equal to 10 µg/L. MOE also advised that if
DO concentrations fall below 6 mg/L, a benthic sampling program may be requested.
Summary of issues raised by the applicants
The applicants raised numerous concerns. (Additional concerns are discussed in the Supplement to this report, pages 232-241.) A key concern is that wastes from cage aquaculture operations are raising phosphorus levels in sediment and in water, which may cause algal blooms. They noted that although background levels of TP in Georgian Bay waters are 3-5 µg/L, MOE uses 10 µg/L as the level at which cage operators are required to take corrective action, despite a PWQO that states if the background TP level is lower than 10 µg/L, it should be maintained at that lower level.
The applicants also noted that elevated phosphorus levels can create areas of low oxygen levels that can change the species of fish and benthic invertebrates that inhabit those areas. The applicants believe that MOE has set an inappropriate threshold level for DO of 6 mg/L, and asked that MOE “confirm that local water and sediment quality is not being impacted” by cage operations by doing an “annual assessment of the benthic community.”
Ministry response
MOE noted that the cage aquaculture industry in Ontario is small compared to other jurisdictions, but that the industry has the potential to grow. The ministry noted that there are emerging issues, such as fish manure management, and that “specific environmental concerns” would continue to be assessed on a case-by-case basis. MOE advised the applicants that there is no evidence that the PWQO for TP and DO are “not protective of water quality” in Georgian Bay, and that the TP objective protects the aesthetics of the water and, in particular, protects against algal blooms.
MOE explained that benthic surveys may be required when the level of TP in sediment is “detrimental to the majority of benthic species.” As TP levels increase, the consumption of DO increases and DO concentrations may fall to levels that can no longer support life. MOE advised the applicants that a benthic survey would assist with understanding the biological effect of low DO concentrations if DO concentrations fell below 6 mg/L. MOE further explained that benthic sampling is required before a new cage aquaculture operation is sited and that sediment monitoring is more appropriate as a screening tool for potential biological impairment than annual benthic surveys.
MOE advised the applicants that it will continue to work with the aquaculture industry to improve environmental performance and to monitor the need for benthic surveys. MOE also indicated that it will continue to monitor the issue of TP, and may re-evaluate its interim PWQO for TP after the framework for phosphorus prepared by the Canadian Council of Ministers of the Environment (CCME) is finalized. This framework proposes a process for determining the level of TP at which further assessment would be required. The ECO notes that the CCME is proposing a trigger range from less than 4 to 10 µg/L TP for waters such as Georgian Bay.
ECO Comment
Despite taking 21 months to complete its review, MOE’s response provided little new information and only vague commitments to improve the environmental performance of cage aquaculture operations. MOE’s response may reflect the tension that currently exists between those federal and provincial ministries currently focused on growing the aquaculture industry, and those that are concerned about the environmental impacts of the industry.
The ECO is distressed that MOE trivialized the applicants’ concerns about TP in water as being primarily aesthetic in nature. Although elevated phosphorus levels can cause algal blooms, they can also cause significant long-term ecosystem changes such as altering species composition, disrupting food chains, and causing the death of sensitive species in an area. MOE’s decision to use 10 µg/L as the trigger level for TP allows large amounts of phosphorus to be added to Georgian Bay before abatement measures are considered. The ECO believes that MOE should not be using 10 µg/L as the trigger level for TP, and should not be relying on a water quality guideline that sanctions the degradation of high quality waters, i.e., better than PWQO levels.
The ECO believes that MOE has ignored the general PWQO that requires waters to be free of contaminating levels of substances that can form objectionable deposits such as fish feces and uneaten food. Furthermore, if sediment monitoring is done only every five years, early signs of degradation will not be detected. The ECO believes that more frequent sediment quality monitoring is required and that further consideration should be given to doing more proactive benthic monitoring.
The ECO urges MOE to take a more proactive approach to defining water and sediment quality policies for cage aquaculture operations, including monitoring and reporting rules, best practices and abatement measures. Continuing to address water and sediment quality concerns on a case-by-case basis rather than developing clear policies does not address the concerns of the public and leaves the aquaculture industry without clear direction. The ECO urges MOE and MNR to work together to ensure that water and sediment quality conditions are added to aquaculture licenses, that they are enforced, and that water and sediment quality are not impaired by these operations.
| This is an article from the 2004/05 Annual Report to the Legislature from the Environmental Commissioner of Ontario. |
Citing This Article:
Environmental Commissioner of Ontario. 2005. "Aquaculture in Georgian Bay – Water Quality and Environmental Monitoring." Planning our Landscape, ECO Annual Report, 2004-05. Toronto, ON : Environmental Commissioner of Ontario. 133-137.
