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Fish die-off on Salmon River could be caused by vitamin deficiency

David Chanatry/New York State Reporting Project
Fishers on the Salmon River. (file photo)

A thiamine deficiency might be to blame for a recent die-off of steelhead trout in the Salmon River.

The Department of Environmental Conservation says it began receiving reports about steelhead trout swimming erratically and dying in the Salmon River and other rivers off Lake Ontario last month. Three fish were sent to Cornell's Aquatic Animal Health Lab, where research scientist Rod Getchell examined the fish for diseases.

"We did our normal work up, looking for bacterial pathogens, viral pathogens, things like fungus or heavy parasite loads," Getchell said. "And we did not find any of those things in the three steelhead trout that were brought to us."

He says a thiamine deficiency is likely the culprit, and believes the deaths may be caused by a diet that can deplete the vitamin's levels, causing the behavior.

"They feed on alewives, and that's a baitfish," Getchell said. "And that baitfish contains a lot of thiaminase, so the enzyme that breaks down this vitamin."

The DEC also has been testing, including injecting the affected steelhead with thiamine, also known as vitamin B1.

"What they noticed was that there was actually an improvement in the health status of the ones that got the vitamin injection."

Dale Honeyfield is a researcher for the Northern Appalachian Research Lab. He has studied the effects of thiamine deficiency in fish since 1995, and says thiamine deficiency often means that the ecosystem is not normal but is not an indication of what exactly is off.

Honeyfield says without the proper levels of thiamine in their bodies, the fish behave differently and eventually die.