Fisheries managers still can't say what caused a massive kill of exotic silver carp in the tailwaters of Barkley Dam, but the sense is that because no native species apparently were harmed, no problem.
Earlier this week biologists were taking samples of dead silver carp in the Cumberland River from immediately below Barkley Dam all the way to the confluence with the Ohio. Roughly, a half-million silver carp died in the area, according to Kentucky Department of Fish and Wildlife Resources estimates.
District fisheries biologist Paul Rister by mid-week said the die-off apparently has ended, although heavy discharge from the dam and flooding conditions have washed away much of the immediate signs of what happened.
Rister said no species other than silver carp - not even bighead carp, the other troublesome Asian carp variety - seems to have been affected. As such, Rister said the most logical cause is a species-specific virus, an ailment that would not sicken other kinds of fish.
Samples of dead silver carp have been sent to biological laboratories, but total results from testing are not expected for two weeks to a month. Initial examinations have not indicated any die-off causes.
Meanwhile, Rister said that some potential explanation could lie in the features of the dam itself. It's only theory for now, but Rister said there is some possibility of a kill spinning off from ridiculously heavy concentrations of silver carp in the tailwaters caused by recent water flow and elevation levels, spawning migration of the fish and a natural inclination of the carp to move upstream.
Rister said one item of investigation is whether huge numbers of silver carp may have driven fish to surge en mass into turbine chutes at the dam in a continuing effort to move into current. Some explanation for the kills may be a gas bubble disease that can result from fish plunging into waters that are super-saturated with oxygen in the turbine area â “ plus numerous fish being struck by turbine blades churning at 60 revolutions per minute.
A quick-spreading virus makes more sense, but a destructive run by thousands and thousands of fish into turbine discharge is a possible explanation that warrants more study, Rister said.
Regardless of the exact cause, managers are at ease because the only species affected appears to be one that's an intruder and an ecological danger to native species anyway.
KDFWR fisheries director Ron Brooks said fisheries biologists essentially see the Barkley Dam kill of silver carp as a good thing. U.S. Fish and Wildlife Service scientists are interested in the cause, pondering whether it might be harnessed to control silver carp numbers elsewhere, Brooks said.
Rister said the huge die-off hasn't made any apparent dent in the vast population of silver carp in the Barkley Dam tailwaters.
He said that, while collecting samples of dead fish there once the kill was past its peak, a total of eight live silver carp jumped into his boat.
n Kentucky turkey hunters are in the final weekend of the spring gobbler season, perhaps bound for a smaller overall bird that may reflect weather conditions harvest this time around.
After topping 32,000 bearded birds taken every year since a record of 36,097 in 2010, Kentucky hunters may fall short of that mark in the fleeting current season. Hunting will end Monday.
This weekend and its last flurry of hunting activity bring the last major opportunity to close a harvest gap. After the third weekend, hunters has reported to Telecheck the taking of slightly more than 24,000 turkeys â “ with stormy weather posing the prospect of hampering hunting through a good part of the ensuing weekday stretch.
Obviously, thousands of hunters have had success, but many, too, have complained about a shortage of gobbling this season. Common anecdotal reports this year held that the turkeys' reproductive season and related behaviors were running behind schedule because of the wintry temperatures extending into spring.
Many reports of gobblers being with hens and resistant to hunters' calling could foretell some improved results if more finally hens move to nesting duties in the last days of the season, leaving an increased number of gobblers again receptive to hunters' yelps, purrs and cutts.
n The spring squirrel hunting season begins next Saturday in the Tennessee portion of the Land Between the Lake. Concurrent with the dates statewide in Tennessee, the spring squirrel quest in the southern portion of the federal recreation area runs May 10-June 8.
The northern, Kentucky part of the LBL will see the spring squirrel season arrive a week later. Coinciding with Kentucky's statewide season, that bushytail hunting stint will be May 17-June 20.
In the LBL, hunters 16 and older must have an LBL Hunter Use Permit as well as appropriate hunting license. The Tennessee daily bag limit, observed in the LBL as well as statewide, is 10 squirrels. When Kentucky's season kicks in, the daily limit in the Kentucky portion of the LBL â “ as well as statewide here â “ is six squirrels.
n The Land Between the Lakes' Woodlands Nature Station next Saturday, May 10, will host its regular spring Birding Bonanza â “ a chance to learn to identify common birds, how to attract varied species to backyard feeders and an opportunity to encounter birds up close at the Nature Station.
Marking International Migratory Bird Day, the Nature Station staff will conduct birding programs throughout the day: "Truly Talon-ted" at 10 a.m.; the "Warbler Walk" of the Adult Nature Series at 11 a.m.; "From Hummingbirds to Hawks: Backyard Birding for Kids" at 1 p.m., and "Welcome Back Hummingbirds" at 1 p.m.
A "Backyard Bird Scavenger Hunt" will run through much of the day, 10 a.m.-4 p.m.
Programs are free with Nature Station admission.
Steve Vantreese is a freelance outdoors writer. E-mail outdoors news to firstname.lastname@example.org or phone 270-575-8650.