Mosquito Fish to Control West Nile Virus?

On 05/15/03, I posted the following message to the WestNileVirus-L listserv:

American University Radio (WAMU - 88.5), an NPR affiliate in Washington, D.C., featured a half-hour broadcast today at 1 p.m. on the Kojo Nnamdi Show on the use of mosquito fish (Gambusia holbrooki) to control WNV. The program included guests from the Virginia Department of Game and Inland Fisheres, York County Mosquito Control, and The Nature Conservancy. The State of Virginia is reviewing applications and issuing permits to local mosquito control authorities to introduce G. holbrooki, even to parts of the State where it is not native, despite the following known or potential detrimental impacts of this species (from the Nonindigenous Aquatic Species website):

1. Recent critical reviews of the world literature on mosquito control have not supported the view that Gambusia are particularly effective in reducing mosquito populations or in reducing the incidence of mosquito-borne diseases.

2. Because of their aggressive and predatory behavior, mosquitofish may negatively affect populations of small fish through predation and competition.

3. In some habitats, introduced mosquitofish reportedly displaced select native fish species regarded as better or more efficient mosquito control agents.

4. Mosquitofish are known to prey on eggs, larvae, and juveniles of various fishes, including those of largemouth bass.

5. Introducing mosquitofish also can precipitate algal blooms when the fish eat the zooplankton grazers, or in an increase in the number of mosquitoes if the fish eat the invertebrate predators.

I worry about the unintended consequences of introducing yet another alien aquatic predator into waters where it is not native. with no guarantee that it will be effective in reducing mosquito populations or the incidence of WNV. I wish this were all a hoax, but I heard it with my own ears!

Cassette tapes of the program are available from WAMU.

Thanks to Diedtra Henderson for pointing me to this article from the Denver Post, which reviews concerns about using Gambusia for this purpose in Colorado.