A vitamin B deficiency among predator fish is now affecting steelhead trout returning to the tributaries of Lake Ontario, and is causing a surprisingly high adult mortality rate.
Section Head for Great Lakes Fisheries Steve LaPan says they first received reports from fishing guides on the Salmon River in Oswego County at the end of November…
"Initially, they were observing fish that were swimming erratically, some of them upside down. When they would roll over to the fish and collect them in a net, the fish would powerfully swim off. They would all of a sudden right themselves, and seem to swim normally...only to swim a short distance and then start the same behavior swimming erratically again."
After that, LaPan says they started to see dead steelhead at the bottom of the river. Researchers at Cornell and other labs discovered the fish were suffering from a vitamin B or thiamine deficiency known to affect other predator fish that feed on alewife, an invasive bait fish that contain an enzyme that degrades thiamine. So, LaPan says they’re trying something they’ve never done before and collecting steelhead that come to the hatchery and injecting them with vitamin B.
"And within 24 hours, they will respond to that injection. So, we're holding those fish in raceways outside the hatchery, and we're feeding them a commercial diet that is fortified with vitamin B. We're confident that if we can keep those fish through the next few months, it will help us reach our egg quality and quantity targets for the spring egg take."
LaPan says they already have experience bathing eggs in vitamin B as another remedy. Meanwhile, he says it’s still a mystery as to why so many adult fish are dying of the deficiency.
LaPan doesn’t expect it to have a significant impact on Lake Ontario’s sport fishery due to the diversity of fish.
