How P.E.I.'s known freshwater mussel species increased 50% in one day

It's been two years since the first live alewife floater was documented in P.E.I. waters. But finding more of the species is proving difficult.

Finding more alewife floaters on the Island is proving difficult

The first alewife floater documented in P.E.I. was discovered in Midgell River in 2018. (M. Sollows/ New Brunswick Museum)

Hannah Murnaghan has loved the outdoors for as long as she can remember, so when the opportunity to look for freshwater mussels in the river presented itself, she jumped right in — literally.

"We see mussels in all the rivers that we work in," said Murnaghan, the co-ordinator at the Morell River Management Co-operative, which manages six rivers: Morell River, Midgell River, Bristol Creek, Marie River, Schooner Creek, and St Peters River. 

These, however, were no ordinary mussels she was searching for. Murnaghan and her team were on the hunt to find an alewife floater.

Originally, only two types of freshwater mussels had been documented on the Island — the eastern pearlshell and the eastern floater. But Rosemary Curley, president of Nature P.E.I., said the alewife floater recently made the list.

"Some of them are hard to tell apart."

'Freshwater mussels they are not very well recognized by people because they live in the bottom of lakes or ponds,' says Rosemary Curley, the president of Nature P.E.I. (Jessica Doria-Brown/CBC )

Curley said the species was originally discovered in the rocky Midgell River back in 2018. At the time, she was accompanying others down by the water hoping to learn more about the eastern pearlshell's habitat.

"It wasn't really my project," she said. "I was invited to help some people who were visiting from the mainland."

The small group was made up of her, Juergen Geist from the Technical University of Munich, Annie Paquet from the Quebec Department of Forest Wildlife and Parks, and Mary Sollows from the New Brunswick Museum.

"As soon as we got there, Mary picked up a shell and she and Annie said at the same time 'alewife floater,'" Curley laughed.

"The alewife floater had never been reported on P.E.I. before. It was newly found," said Curley.

Travels by fish

How exactly this specific mussel made its way into P.E.I. waters remains unclear. Curley, though, said she believes it was transported by a fish. 

"Their life cycle includes a stage where they have a larval form called a glochidia," she said. "They attach to the gills of their host fish.

"As they mature, they'll drop off wherever the fish happens to be and they develop further into a mature clam in the river."

Nature P.E.I. says the alewife floater can have a shell length ranging from 100 to 165 mm and the outside of their shell tends to get darker as they age. (M. Sollows/ New Brunswick Museum)

According to Nature P.E.I., while additional shells were discovered, only one live specimen was collected and sent to the New Brunswick Museum.

"So this summer, I decided to see if I could find some other sites for the floater," said Curley.

Quest to find more

She began her new search by messaging watershed groups across the Island.

We thought we might have a chance at finding it.​​​​​​-Hannah Murnaghan,  Morell River Management Co-operative

"They were helpful because being the experts they are in their watersheds, they knew where some of these mussels were living," she said.

"We sent her a message and we told her we'd be interested in helping her try and look for the mussel," said Murnaghan, with the watershed at Morell River Management Co-op.

"We did know there was gaspereau in Bristol Creek, which is the species the alewife floater uses to get up Bristol Creek so we thought we might have a chance at finding it," said Murnaghan.

"But we didn't have any luck."

Hannah Murnaghan says while they didn't find any alewife floaters in Bristol Creek, they did find the other freshwater mussels. (Submitted by Morell River Management Co-operative)

So for now, even though leads on how a single alewife floater ended up on P.E.I. have run dry, Murnaghan said she's not giving up. 

"Going forward we'll probably pick [the mussels] up and see what species they are," she said.

"Although we didn't have any luck finding it in our field day with Rosemary, we will be keeping an eye out."

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