People on Quadra Island, B.C., are concerned that leeches may be killing salmon in a spawning creek.
Several dozen chum salmon that had not yet spawned have been found dead by residents.
Bill Dubois, who has lived near Hyacinthe Creek for decades, says he has seen leeches on salmon who returned to spawn in the past.
But he says he's never seen anything like what happened this year.
"They are getting infected by literally hundreds and in some cases thousands of baby leeches and they are getting into their gills," Dubois said.
The leeches are believed to be a natural phenomenon, but the amount this year is concerning, said Lauren Miller, a director with the Quadra Island Salmon Enhancement Society.
"I think we just need to know a lot more before we know how concerned to be," she said.
"It's always a big concern when salmon are dying when they are facing all kinds of other obstacles in this world."
People on Quadra Island have preserved some of the dead fish in their freezers.
They hope they can be tested by scientists to determine what caused their death.
No one from Fisheries and Oceans Canada was available for comment.