Researchers solve salmon extinction in Lake Ontario
Human activity contributed to wiping out population in freshwater, researchers found
For hundreds of years, indigenous communities on the shores of Lake Ontario fished for Atlantic salmon, a staple in what became one of the world’s largest freshwater fisheries.
But thanks largely to human activity, that population disappeared by the 1900s. Since then, scientists debated whether the historic salmon population migrated to the Atlantic Ocean, or stayed in the freshwater lake for their entire life cycles.
Astudy released Tuesday has addressed that debate.
It found that Lake Ontario salmon completed their entire life cycles in freshwater without ever making the taxing journey to the Atlantic Ocean.
It’s information that Eric Guiry, a PhD candidate at the University of British Columbia and lead author of the study, hopes will help in future attempts to reintroduce a sustainable Atlantic salmon population to Lake Ontario.
“Knowing whether or not the original population migrated could help conservation biologists figure out what stocks of salmon to use when they go out trying to bring a viable population back to Lake Ontario,” he said.
The authors of the study, published Tuesday in Scientific Reports, were able to determine the migration patterns of the historic salmon using stable isotope analysis, something Guiry explains is based on the premise of “you are what you eat.”
“Different foods have distinctive isotopic signatures,” he said.
He added that measuring those signatures, the authors could determine what the salmon ate, and where that food was from.
“We expected salmon that had migrated to the Atlantic Ocean to have a dietary signature that reflected marine foods, whereas salmon that had only lived in Lake Ontario would have a diet that reflected freshwater foods.”
The authors studied salmon bones from different indigenous and European archeological sites around the western side of Lake Ontario, as well as skin samples from salmon that were stuffed and mounted for display. One of the fish tested was stuffed for the 1883 Great International Fishers Exhibition in London, England. Another fish hangs at the Royal Ontario Museum, which had an assistant curator co-author the study.
The analysis supported the idea that although there were no physical barriers preventing salmon from returning to the Atlantic Ocean, Lake Ontario was productive enough that salmon populations adapted and were able to complete their entire life cycles in freshwater.
There are currently several conservation efforts working on establishing a self-sustaining Atlantic salmon population in Lake Ontario. The Ontario Federation of Anglers and Hunters (OFAH) has been working with the provincial government since 2006 to try to restore the population.
Chris Robinson, co-ordinator of the OFAH Atlantic Salmon Program, said the conclusions support their plan of trying to incorporate different types of salmon into the system.
“We always believed that was the case, but this is probably as conclusive as we can get without getting a time machine,” Robinson said.