Hikers and birdwatchers visiting the normally serene Lake Brittle over the weekend might have been alarmed when they came across hundreds of dead fish washed up on the shores of the lake and others floating belly down in the water off the fishing pier. Lake Brittle is a 77-acre reservoir created in 1953 as a public fishing lake in Fauquier County, just east of Warrenton.
Ring-billed gulls hovered above the mounds of dead fish, screeching, swarming and plucking the heads of the fish. The unsightly scene raised a lot of questions among lake visitors, especially for the health of Lake Brittle.
But there’s no need to worry, says John Odenkirk, a fisheries biologist with the Virginia Department of Wildlife Resources.
“A shad die-off event is a completely natural occurrence. It’s very common at this time of year” and it doesn’t mean any environmental issues for the ecology of the lake, he said. .
Odenkirk identified the silvery blue-green fish found on the shores of Lake Brittle as gizzard shad, a smaller fish that is very sensitive to sudden changes in temperature. He said gizzard shad deaths are common, especially at this time of year. In late winter, when temperatures can reach 60 degrees during the day and then quickly drop to teenage temperatures at night, these fish sometimes “roll over and die”.
Odenkirk said gizzard shad tend to take up fewer nutrients from cooler waters during the winter months, which can make them weak and more susceptible to mass mortality.
The gizzard shad is not a fish that people eat because it is too small and does not taste good. Odenkirk said gizzard shad are sometimes sought after by commercial boatmen who like to use them as crab bait because of their size and oil content.
As for the hundreds of dead fish littering the shore, Odenkirk said nature will take care of itself and there is no need for the VDWR to intervene in the cleanup process. He said cold air temperatures retard the decomposition process, but also reduce odors from dead fish, which can be a nuisance to nearby neighborhoods in warmer months.
While the 2- to 3-pound shad may be too heavy for a seagull to pick up and eat, Odenkirk said he anticipates many other animals will certainly feast on the oily fish.
“Everything that’s out there — raccoons, crows, vultures, turtles — there’s tons of scavengers out there and they’re going to use up all that protein lying around,” he said.
Odenkirk said he expects the piles of dead fish to disappear within days with no signs of mass mortality by next weekend.
“In less than a week, you’ll be hard pressed to find residual dead shad.”
That is, unless there is a secondary mortality event, which Odenkirk says is also a common occurrence, especially in bodies of water with large biomasses of gizzard shad, such as Lake Brittle.
As well as being part of the food chain for animals in the forest surrounding Lake Brittle, Odenkirk said gizzard shad are great for your garden or compost pile and invite gardeners to come and grab a bucket. Gizzard shad is “a wonderful thing to put in your garden. It makes great compost as long as your dog or cats don’t dig them up and drag them around.