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Golden Alga in Texas

Archived News Release

May 30, 2001

Granbury Survey Assesses Effects of Fish Kill

Much concern has been voiced about the February/March golden algae kill in Lake Granbury. Texas Parks and Wildlife Department recently evaluated the effects of the fish kill using gill nets and electrofishing. Overall, the results were very reassuring.

Gill nets were used to assess striped bass, white bass, and all three catfish species on April 30. Electrofishing was conducted May 1 and May 8 to assess bass and prey species. The primary goal was to verify the presence, size structure, and body condition of predator and prey species.

Catch rates for striped bass were 0.4 fish per net, compared to an average of 2.0 for previous surveys. While this may indicate a reduction in the lake's striper population, it is difficult to say for certain, as seasonal migrations or other factors may have reduced catch rates. Fish caught ranged from 18 to 23 inches in length, and their overall condition was good, with no skinny fish. White bass catch rates were 1.9 fish per net, similar to the average of 2.4 for surveys conducted in the 1990s. White bass ranged in size from 3 to 14 inches, and their condition was also good.

Channel catfish were collected at a rate of 5.5 per net, similar to the previous decade's average of 4.4, and ranged from 9 to 22 inches in length. Flathead catfish catch rates were 0.8 per net, also similar to the recent average of 1.0, and measured 19 to 26 inches. The lake's small blue catfish population also held its own. Body condition of all catfish was excellent. The sizes of fish collected were similar to those collected in previous surveys, indicating that the golden algae did not discriminate against either large or small fish.

Electrofishing samples in the 1990s were collected during the month of October, rather than May. This made it impractical to compare current and previous catch rates; consequently, species sampled by this method were examined only for size and condition. Largemouth bass collected while electrofishing ranged from 4 to 20 inches in length, and spotted bass measured between 9 and 15 inches. There was no indication of a significant decline in either species. Sizes of bluegill, gizzard shad, longear sunfish, threadfin shad, and other sunfish and minnows were similar to previous years.

Based on these results, TPWD has concluded that stocking of prey species in Lake Granbury appears unnecessary at this time. The lake remains slated for stocking striped bass in early summer. Unlike all other species in the lake, striped bass numbers must be maintained by stocking.

Previous gill net and electrofishing surveys on Granbury were conducted every three years in accordance with TPWD's standardized sampling methods. A full survey is planned in the fall and winter of 2001. In addition to the species listed above, this survey will include trap nets to evaluate the crappie population.

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Aditional Information:

Would you like to know more?
The Biology of Golden Alga summarizes what we know about the alga and its toxins.

Where does golden alga fit compared to other single-celled organisms?
The Golden Alga Family Tree gives examples of and information about golden alga and other protists.

What does golden alga look like?
TPWD Golden Alga Images has photos of fish kills, golden algal cells, and short videos of live golden alga. These images may be used for noncommercial/educational purposes as long as TPWD is given credit and other site policies are followed.

Golden Alga Information Card: TPWD has collaborated with TCEQ and other entities to produce a golden alga information card(pdf document). The purpose of this card is to educate the public on golden alga blooms and answer some common questions. Hard copies of this card are available for free by contacting 512 389-8750.

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