By IAN MCINROY
Fish in Lake Simcoe could soon be catching a break.
Long-term provincial efforts to reduce phosphorus levels in the lake will go a long way to restoring fish populations, experts say.
But an environmental watchdog says the phosphorus reduction strategy announced earlier this week doesn’t go far enough.
The 35-year-long strategy of the Ministry of the Environment (MOE) will take place in phases, and is intended to identify — and reduce — major sources of phosphorus entering Lake Simcoe and its watershed.
The announcement of the strategy comes on the heels of the first anniversary in June of the Lake Simcoe Protection Plan, which the ministry calls a “road map to help restore and protect the health of the lake and its watershed.”
Too much phosphorus leads to excessive plant growth and when those plants die and decay, oxygen levels are sucked out of the water.
About 30 years ago, more than 100 tonnes of phosphorus made its way into the lake each year.
After forts, that has dropped to 72 tonnes per year and the long-term reduction strategy would see that drop again to 44 tonnes.
There are a number of ‘stressors’ that impact the fish communities of Lake Simcoe — invasive species, climate change, exploitation and development — that combine to affect the entire fish community in the Lake Simcoe ecosystem, according to Ministry of Natural Resources’ (MNR) Lake Simcoe aquatic resources management biologist Jason Borwick.
“When it comes to the coldwater fish community, however, excess phosphorus and reduced oxygen levels remain the major roadblock preventing (the fish population) from becoming naturally self-sustaining,” he said.
Those populations — lake trout and whitefish — were severely impacted by excess phosphorus and led to population crashes in the 1960s and 1970s, Borwick said, and the MNR conducts large scale stocking programs to maintain the lake trout and whitefish populations.
But the fish are making a bit of a comeback on their own, he said.
“More recently, coinciding with Lake Simcoe water quality improvements, naturally reproduced lake trout have been documented every year since 2001, something we haven’t seen in over 20 years,” Borwick said. “Despite the fact that lake trout are once again reproducing naturally, the lake trout population is still dominated by stocked fish.”
Liz Unikel, a senior adviser with the MOE’s Lake Simcoe Project, said to have a self-reproducing lake trout population, the water where the coldwater fish community lives must contain at least seven milligrams/litre of dissolved oxygen.
“Research shows us that if we reduce phosphorus entering the lake by 40% to 44 tonnes per year, we would achieve that target,” she said, adding the reductions over the last 20 years have made a difference.
“This has increased dissolved oxygen levels to around five milligrams/ litre and we are starting to see some naturally reproducing lake trout,” Unikel said. “But we have further to go to reach the desired outcome: a renewed coldwater fish community.”
Claire Malcolmson, Lake Simcoe Campaign co-ordinator for Environmental Defence, said reducing phosphorus is important, but just how the strategy would do that is still unclear.
“This strategy was intended to identify specific reduction goals and timelines and all these things need to be done. But it fails to lay out a plan for reaching a goal,” she said. “The goal is to get down to 44 tonnes per year, but they don’t say how they’re going to do that. And they don’t have the technology to reduce the pollution from (future) development.”
Increasing growth pressures around the lake will make protecting it even more difficult over the coming decades, Malcolmson said, adding the province should apply pressure to watershed municipalities to ensure they have the health of the lake in mind when they make their planning and development decisions.
“We need to know where the brakes are in growth,” she said. “We’re concerned there will be a bunch of growth approved and the community — and the environment — won’t see any benefit (from the strategy).”
Triggers — such as the environmental health of streams, or whether biodiversity in an area is better or worse — would determine whether a community was doing its part to protect the lake, she added.
“There is an opportunity for the province to apply conditions to things like the expansion of sewage plants or growth (before approving them),” Malcolmson said.
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