Ellen George, a Cornell University graduate student, attaches a tiny radio transmitter to the back of the bluish-green fish and carefully releases it into the icy waters of Chaumont Bay.
“They like it cold,” says George. “The females won’t come into the bay to spawn until the water is about 42 degrees or colder.” George has been working for three weeks near this shoal with Nature Conservancy researcher Matthew Levine to track the last known population of native lake herring, sometimes called "cisco," in Lake Ontario.
What are Cisco?
A prey fish, lake herring were once abundant in the lake but their numbers have been dramatically reduced by overfishing, historic pollution issues and aquatic invaders. Problems with the fishery began with the collapse of the lake's Atlantic salmon population and the arrival of alewife, a baitfish that although considered an invasive in the region is now the main food source for predator species such as chinook salmon and brown trout.
What We're Doing
A joint effort by The Nature Conservancy, the New York Department of Environmental Conservation (NYS DEC), the U.S. Geological Survey (USGS) and Cornell University aims to confirm where the lake herring are spawning in Chaumont Bay and discover any roadblocks they face. Ice fishermen and other anglers were the first to call this particular shoal to the Conservancy’s attention.
Meanwhile, Conservancy staff Darran Crabtree and Stevie Adams are surveying other bays in the lake to see if ciscos are present there. Their search of Irondequoit Bay last year did not turn up lake herring, nor did this year’s survey of Sodus Bay.
“We definitely got the less exciting part of the job,” says Crabtree. “But confirming the absence of these fish is important, too. These surveys will help NYS DEC and USGS determine where to stock hatchery-bred lake herring in the future.”
Using the Data
Ultimately, the information both teams gather will inform efforts to rebuild healthy Great Lakes food webs where native fish thrive.
As for George and Levine, they captured and radio-tagged 16 female and 8 male spawning lake herring in Chaumont Bay and spent two weeks using a radio receiver and an GPS-linked iPad to track them, at times even skiing out on the frozen shoal to pick up signals.
“Interestingly, none of the fish were using the shoal when we radio-tracked them,” said Levine. “They could be spawning at a different location, or on the shoal at night before spending the day in deeper waters.”
With spawning season complete, that will be a mystery for another season.
By Kate Frazer
Kate Frazer is a communications manager for The Nature Conservancy based in Central and Western New York