Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, January 20, 1994 TAG: 9401200021
SECTION: SPORTS PAGE: B-2 EDITION: METRO
SOURCE: BILL COCHRAN
DATELINE: LENGTH: Medium
Cold weather is the reason.
Plummeting temperatures between Christmas and New Year's Day started the massive die-off at the popular Southside Virginia lake. State fish officials believe it continued as temperatures nudged even lower the past couple of weeks. Much of the evidence is under ice.
"We won't know what is going on until we have the chance to go out and do some sampling," said Bill Kittrell, a fisheries biologist supervisor for the Department of Game and Inland Fisheries.
When Kittrell took the water temperature at Kerr's Bluestone Creek on New Year's Eve, he found it hovering at the 40-degree mark.
"Anything below about 45 degrees, the fish starts stressing," he said. "When I checked it, the fish were washing in and the gulls were picking them up."
No species other than the threadfin appeared to be in trouble.
Checks at Smith Mountain Lake have failed to turn up any dead threadfin shad, said Mike Duval, a fisheries biologist supervisor. In fact, they have failed to turn up any shad - period.
"In talking with some of the fishermen up there, they are not seeing any of the small shad," said Duval. "They dropped down about the first part of December, when we started getting the cold winds, and haven't been seen since."
That could mean the threadfin in Smith Mountain have found a warm-water refuge and will escape a major die-off, he said.
"I think they are going to get out of that real cold water near the top and are finding some warmer water, maybe springs, which will be warmer this time than the rest of the water," Duval said.
The threadfin was discovered in Smith Mountain for the first time last summer, probably transferred there as bait by fishermen.
"They were in the Roanoke River arm in great abundance," said Duval. "Anything less than 6 inches, by and large, was threadfin shad in the Roanoke River arm. That was not the case on the Blackwater arm, where alewives seemed to be very abundant."
Threadfin provide a welcomed bite-sized meal for game fish, and in that capacity can be an important species, Duval said.
On the negative side, the lack of winter hardiness of this native of Mexico can cause problems. A sudden cold-weather die off can leave Mother Nature's cupboard bare. To make matters even worse, threadfin often displace established species, like gizzard shad, when their populations build. So if they disappear, the void is even greater.
"This spring could be crunch time for some fish species," Kittrell said of the loss of threadfin in 50,000-acre Kerr. "There just may be a little more competition for a reduced forage supply."
But Kittrell doesn't anticipate any adverse long-term effect because Kerr also has good numbers of baitfish in the form of gizzard shad, alewives and blue-backed herring. What's more, the threadfin is a prolific spawner that can bounce back quickly.
A major forage-fish loss at Smith Mountain could be more troublesome, especially for striped bass. At Kerr, striped bass are limited by the lack of summertime habitat; at Smith Mountain the major limiting factor is food, Duval said.
The lack of food has caused fish officials to proceed with a striped bass stocking program that is more conservative than many anglers would prefer. That makes the loss of any baitfish bad news.
by CNB