Area debates impact of fish farms on ecosystem
http://www.growfish.com.au/content.asp?contentid=12097
Adrian Alleyne
Lake Diefenbaker is one of the most popular and cleanest lakes in southwestern Saskatchewan, but future plans for three additional fish farm pens along the lake are causing some concern about the environmental impact to the man-made lake.
Wild West Steelhead is an Edmonton based aquaculture company that plans to expand its production on the lake.
But some residents fear there may be an accident, such as a number of fish pens breaking and allowing thousands of mature fish to enter the lake, which can hurt the lake's ecosystem and cause other environmental damage.
According to Gary Dunn, president of the Elbow and District Wildlife Federation, approximately 600,000 to 700,000 fish have escaped from the fish farm since it started business in 1992. And "it essentially changed the fish dynamics of this lake significantly," Dunn said.
Some other concerned residents believe that more testing needs to be done, in order to determine if the fish pens are hazardous to the environment. One of the major concerns is the effect the fish farm will have on water quality.
But the proposed expansion has its supporters as well.
"We also live downstream from a city with a million people or more in Calgary and Medicine Hat. How much do they contribute (to pollution)?" said David Cross, a resident of Elbow. "I think there's many factors and I'm not prepared to blame the fish farm."
According to Cross, there are other causes that need to be considered when discussing the possibility of algae appearing in the lake. One is agricultural chemicals. Since a lot of the land around the lake is sloped, a lot of these chemicals can end up in the lake, he said.
"If water samples indicate that the fish farm is having a negative effect on the lake, then I'm definitely against expansion. If the science indicates that it isn't having a negative effect on the lake then I have no opposition to it," said Bryan Cafferata, owner of Lakeside Marina Services in Elbow.
"I think that the expansions can be done and co-exist with the existing users without causing any huge problems," added Cafferata.
However, there are other residents who believe the fish farm is the major concern, and it has no place on their beautiful lake.
The Elbow and District Wildlife Federation is opposed to the pens, unless tests prove that the farm has not and will not have a negative effect on the lake. And federation members recently started a petition requesting more testing.
The federation gathered 350 signatures from petitions sent to three towns and another 60 petitions were sent out in the last two weeks.
Dunn has a number of other concerns related to the fish farm expansion.
"There's a number of inputs for phosphorus, but the fish farm is definitely one and we know exactly how much they're putting in there," said Dunn. "Roughly 20 tonnes of phosphorus (goes) into this lake each year, and the phosphorus feeds the algae in the lake."
Dunn, a retired aquatic quality analyst for Environment Canada, has been expressing concerns since the fish farm was first put in place.
"(We) expressed extreme concern that the phosphorus loading to the lake from the fish farms could cause significant changes in the algae and weed growth in the lake," said Dunn, referring to Environment Canada's initial assessment of the fish farm development.
"I've done some brief calculations on it, some engineering discharge calculations, and it's approximately equivalent to a town of 30,000 people dumping its entire raw sewage into this lake," said Dunn.
But he does admit that there could be other factors at work, such as cattle on the shoreline and runoff from agricultural land. But according to Dunn, any treatment on these problems would cost a fortune, while "(saying) no to an expansion is a simple solution to preventing any more phosphorus from entering the lake."
As for further studies on the lake, there is currently a one year study being conducted by the University of Saskatchewan. The purpose is to collect phosphorus and nitrogen samples at different locations along the lake. Then the U of S researchers will try to determine where the phosphorus is coming from and how massive the algae growth will be on the lake.
So is there any possibility of making those opposed to the expansion happy?
"If they could move the fish offshore and put them in ponds offshore and then the phosphorus from the fish food and from the feces can be held back and then treated before it's released into the lake," said Dunn. "That's the only way that I can see that this operation would not cause significant problems with algae growth in the lake."
As for Wild West Steelhead, the company had no comment on the expansion, but the proposal the company submitted to Saskatchewan Environment in July 2006 outlines its intentions.
"In order to continue to build on our successes, we must continue to expand our production. Recently we have had to turn down potential sales programs with large distributors and retailers due to insufficient production," the company said in its proposal.
"We are getting into a situation where we are too large to be a small producer, but too small to be supplying major retail chains. In order to remain competitive we need to take the next step and increase our production."
Wild West was hoping to increase its production from 1,450 tonnes to 1,900 tonnes for 2008 and 2009, then increase it once more to 2,200 tonnes in 2009 and 2010.
As for the setup at the new locations, it would consist of "10-12 floating cages, each approximately 50 feet long by 50 feet wide and supporting a net which would be approximately 40 feet deep."
"Each site would offer approximately 30,000 cubic metres of holding space within the nets, yielding approximately 300,000 kilograms of Steelhead production annually at peak capacity."
The proposal also notes that "the lake as a whole is one of a select few in Saskatchewan which would be suitable for large, cage culture operations as inflow continues through the winter months. There is very little risk of 'winterkill,' which can be problematic in smaller, colder lakes with no constant inflow."
The proposal also addresses the possibility of the expansion having a negative impact on the water quality.
"The fundamental requirement of any successful aquaculture operation is a healthy aquatic environment in which to produce a healthy product. The success of our business depends on this.
"Wild West Steelhead has now been in operation on Lake Diefenbaker for more than 10 years, first as AgPro Fish Farm, after that as CanGro Processors and finally as Wild West Steelhead. Our water sampling program over this time period has shown that we have had no negative impact on water quality in the lake," the proposal stated.
"Furthermore, with the exception of minor incidents of cold water disease in winter, which is endemic to the lake, we have had no significant disease concerns in this 10 year period and ... we believe we have demonstrated our commitment to environmental sustainability and will continue to do so in the future."
Wild West Steelhead also answered the question of phosphorus intake going to the lake. A report done by Canadian Aquaculture Systems in 1999 stated "there is evidence that Lake Diefenbaker is a phosphorus-limited system."
That led Wild West to propose that "some level of phosphorus inputs from cage culture operations would be beneficial to the aquatic environment."
Whether or not Wild West Steelhead is allowed to go forward with its complete expansion plan remains to be seen. The company recently experienced a set back in the summer, when a fire damaged one of their buildings. The cause of the fire is still under investigation.
What is clear, however, is that there is a long way to go to ensure that all parties involved in this situation will be happy with the final outcome.
