By George Brown
After a lazy summer of fishing, the Ponoka Lions Club has added to the rainbow trout stocks at Centennial Park.
The annual fall re-stocking was carried out last week by Max Menard from Smoky Trout Pond west of Red Deer.
Lions Club member Bob Peters, who oversees the pond, said the club adds fish to the pond every fall after a summer of heavy fishing. The provincial government stocks the pond with about 500 rainbows every spring.
“We try to promote the pond is for the elderly and for the children but we can’t restrict it,” Peters said.
Menard delivered about 185 eight- to 10-inch rainbow trout that were hatched last October. “We get about one inch to one and a half inches per month of growth on them.”
The fish could use another month or two of growth but the majority put into the pond are ready for the frying pan.
Smoky Trout Pond raises about 100,000 fish per year; primarily rainbows, brook trout and grass carp. Fish moved and stocked into ponds by Menard have a nearly 100 per cent success rate, especially if the pond’s oxygen content is high.
The oxygen level in the Centennial Park pond was acceptable — about five to six parts per million. The quality of oxygen would be less at lower depths.
The fish pond could benefit from additional aeration to help fish over-winter, Menard said. As the pond gets older, it contains less oxygen. “Over time, they age.”
Peters said the Town of Ponoka is concerned additional aeration might weaken the ice and prove a danger to recreational skaters on the pond.
But Menard said aeration could be pumped into the pond “right up until early November and then shut off and then fired up again in early April just before break up.”
“It still will give you a big improvement in water quality.”
When the fish were put into the lake last Wednesday afternoon, the water in the pond was 18.5 degrees C — less than two degrees warmer than the water they were transported in.
“You could temperature shock them up to 10 degrees C as long as the water they’re going into isn’t much more than 20 degrees C,” Menard explained.
Putting fish into water 24 to 25 degrees C could be fatal, Menard said. “They don’t like hot water.”
The water in ponds and lakes turns over twice a year, bringing nutrients from the murky depths up to the top, encouraging more growth of algae and duckweed. “Every year it gets a little thicker.”
Menard said a heavy rain will also turn the water over because the “cool rainwater is more dense and it actually sinks down to the bottom as in it runs in and displaces the bad water in the bottom and mixes it up.
“If you get oxygen into the sediment layers it keeps the nutrients tied up in it and it doesn’t cycle back into the water column.”
Peters said the Lions Club has talked about draining the pond somewhat and cleaning out some of the accumulated silt. “At one time it was 30 feet deep and now they say it’s between 17 and 18 feet deep.”
The fish in Centennial Park pond don’t need any supplemental feed. Menard said it’s a healthy pond with freshwater shrimp, leeches, snails and fly hatches.
“They’ll eat whatever goes past their snout.”