PLATTSBURGH — An ongoing study looking into whitefish in Lake Champlain has found a thriving population hidden deep in its murky depths.
The whitefish is a popular sport and commercial fish in the Great Lakes, where it has faced some major problems of late, but it has become a widely ignored bottom feeder in Lake Champlain.
“The whitefish population in Lake Champlain is doing fine,” said Dr. Ellen Marsden, a University of Vermont professor and scientist who is spearheading the whitefish study.
“Everything seems to be going well for them: Their fertility looks good, they’re eating well, they have good growth and low mortality.”
CHANGE IN DIET
Whitefish are a long-lived species, surviving a quarter century or more. The Lake Champlain research project has shown strong consistency in age groups with no discernible gaps that might suggest a die-off problem during any given year over the past few decades.
Marsden turned her attention to Lake Champlain whitefish as a natural progression from research she has assisted with in the Great Lakes.
“In recent years, there have been some dramatic changes in whitefish populations (throughout the Great Lakes), primarily because of a change in their food source,” she said.
A major portion of the whitefish’s diet in the Great Lakes has historically focused on a shrimp-like burrowing creature called diporeia that has also seen a dramatic decline in numbers over the last decade.
Although a cause for the drop in diporeia is not certain, scientists believe the Great Lake’s increase in zebra mussels has had a dramatic impact on the crustaceans.
“Subsequently, the whitefish got into trouble because they didn’t have their favorite food, and they started to eat zebra mussels, which are not a good source of food,” Marsden noted.
“In Lake Champlain, we don’t have abundant numbers of diporeia, so the whitefish’s old food source has not been damaged. That’s how my interest in this lake’s whitefish population got tweaked.”
The only study on whitefish in Lake Champlain took place 80 years ago when the species was important commercially. Though it has been largely forgotten, Marsden felt compelled to see if zebra mussels were playing a role in the health of Lake Champlain whitefish as well.
“Basically, what we found is that they are not eating zebra mussels,” she said. “Even though the (lake) bottom is lined with zebra mussels, they are for the most part ignoring them.”
The whitefish diet here varies. They eat mostly fish eggs — including their own species — during the spring and switch to a crustacean commonly called the opossum shrimp in the summer. They feed mostly on snails during the rest of the year but continue to avoid zebra mussels.
“From a biological standpoint, this raises an interesting question,” Marsden said. “What is the motivation for eating something — in despair because a favorite food is gone or eating it simply because it’s there—”
As commercial fishing on Lake Champlain declined in the early 1900s, the interest in whitefish both commercially and as a sports fish also disappeared.
“Today, anglers don’t even seem to know what they are,” Marsden said. “It’s not a fish that you would accidentally catch if you’re looking for something else.”
In other areas, the whitefish is still a prized sports fish, she added. In Maine, for instance, whitefish tournaments are held throughout the season. They also remain a popular seafood choice in the Midwest and even in New York City, she added.
Marsden believes the Lake Champlain whitefish population could easily handle an active interest from sports anglers and suggests that actively seeking them out could pose a new challenge for anglers.
The adult whitefish grows between 17 and 22 inches in length and can weigh from 2 to 4 pounds. The record catch weighing in at 41 pounds was taken from Lake Superior in 1918.
E-mail Jeff Meyers at: firstname.lastname@example.org