Re­searchers solve salmon ex­tinc­tion in Lake On­tario

Hu­man ac­tiv­ity con­trib­uted to wip­ing out pop­u­la­tion in fresh­wa­ter, re­searchers found

Toronto Star - - GTA - ALICJA SIEKIERSKA STAFF RE­PORTER

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.

BRIAN BOYLE, MPA, FPPO

A Lake On­tario At­lantic salmon on dis­play at the Royal On­tario Mu­seum. The stuffed fish was one of five stud­ied by Eric Guiry and his col­leagues.

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