Fish Kills Have Anglers, Biologists Concerned
Galen Jons & Spencer Dumont, Fisheries Biologist
The on-going fish kills at lakes Possum Kingdom and Granbury have many area anglers very concerned. The fish kills are caused by excessive concentrations (blooms) of a bio-toxic golden alga Prymnesium parvum, a microscopic plant that exists in the Brazos River watershed. The bloom at PK, first reported on January 11, has killed an estimated 175,000 fish, while the more recent bloom at Lake Granbury has killed an estimated 261,000 fish. Texas Parks and Wildlife biologists continue to monitor and investigate these fish kills.
The golden alga was relatively unknown in the western hemisphere prior to 1986, and was first discovered in Texas during a fish kill on the Pecos River. It has also been found in the Colorado River basin. It is unknown whether the alga has always been present in Texas, or if it is a relatively recent introduced exotic.
Normally undetectable, the golden alga is usually only noticeable during blooms, when it imparts a yellowish to golden-brown color to the water. The alga produces a mixture of toxins collectively called prymnesin, which inhibit ion and gas exchange in gill-breathing organisms. The toxin is diminished in saline conditions, and also under ultraviolet and visible light. The toxin appears to be most effective in slightly brackish waters (where the golden alga thrives) and during extended cloudy periods.
While the fish kills have been significantly large in lakes Possum Kingdom and Granbury, it is too early to determine what effect they will have on sport fishing. Most of the fish killed have been forage species, such as gizzard shad and freshwater drum,
although game fish have also been affected, as well as clams. The algal toxin in not known to harm other species or humans, but it's always a good idea not to pick up dead fish to take home to eat.
TPWD officials are concerned that golden algal blooms may occur in Lake Whitney, downstream from Lake Granbury, but there are no indications thus far. No other lakes have reported any such fish kills. Sunny weather will slow or eliminate the fish kills, but we also need rain in the area - it's a Catch 22 or sorts.
Record Crappie Caught at Ft. Phantom Hill
Crappie fishing has been picking up out at the lake. Look for fish
around brushpiles, rocky drop-offs around Johnson Park, and in the flooded
grassy areas in the hot water discharge of the powerplant.
Texas Parks and Wildlife Dept.
5325 N. 3rd
Abilene, TX 79603
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