Officials with the province say over 2,000 brook trout are dead after a fish kill last week in the Montrose River in western P.E.I.
The affected area of about five kilometres stretches from the Confederation Trail above Route 2 near Alma down to Marchbanks Pond.
The dead fish were discovered on Friday by a landowner who has a section of the stream passing through his property.
"The fish had been dead for more than a couple of days," said Rosanne MacFarlane, a provincial freshwater fisheries biologist who responded to the incident Friday.
"We did the best we could on Friday and then the cleanup continued on Saturday."
Provincial conservation officers responded to the kill, as did both provincial and federal representatives from the respective departments of environment. The cause of the kill has not been determined.
Complications of decomposition
The collection of the fish was complicated by the fact that many of the fish had already started to decompose.
"Some of them could not be retrieved just because they were in deep pools, and then visibility is also an issue," said MacFarlane. "As soon as you walk through a filthy stream like that, you lose your visibility."
Officials said "a couple hundred" fish could not be retrieved during the collection.
"I'm mostly looking at the condition of the fish and the condition of the stream ... so I intend to go back within the next couple of weeks and will do some assessment of what's remaining just to see how much of an impact that the event had on the system," MacFarlane said.
Third kill on the Montrose
This is the third reported fish kill in this section of the Montrose River since 2010. The first was in July 2010, followed by August 2017.
"We had one three years ago on that same stream," said John Lane, co-ordinator of the Cascumpec Bay Watershed Association. "It wasn't significant, and I think it wasn't because maybe there had been another one previously that killed most of the fish, and then you can only kill a fish once.
"But the population, that stream, we knew there was something askew."
Lane received the call from the landowner who originally found the dead fish on his property. He sent his team to have a look, which included those who had helped with previous fish kills in the area.
"When we saw that there were significant numbers, we pulled right out because then it becomes a case of we touch nothing and let the investigators do their job, which is the province's job," he said.
Sometimes it's very difficult to pinpoint what exactly may have killed the fish - Roseanne MacFarlane, Freshwater Fisheries Biologist.
For Lane, receiving the call Friday did not make for a happy day.
"I'm sure like every other co-ordinator who's had a fish kill, it just takes the gut right out of you… It just takes the wind right out of your sails," he said.
Second P.E.I. kill in 2020
This is the second reported fish kill in the province this year. The first was a manure spill in Cousins Pond on June 3.
Officials said the cleanup for the Montrose incident has been completed and the Department of Environment, Water and Climate Change is continuing to assess the area to determine next steps to help the fish population recover.
"It's never a positive thing for an ecosystem to lose a number of a species like that," said MacFarlane.
Although the cause of the incident has not been determined, MacFarlane says past fish kills on P.E.I. have resulted from natural causes — like low oxygen in a watercourse due to frozen ponds, post-spawning stress and high water temperatures — as well as causes like pesticides.
The source of the Cousins Pond manure spill was later determined, but not made public.
Both MacFarlane and Lane said determining a cause for the Montrose River incident may be challenging due to the state of the fish upon discovery.
"The water is flowing constantly, so anything that might have been present that could potentially kill the fish would be gone at this point," MacFarlane said.
Provincial officials said the incident remains under investigation.
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