Fish disease poses no risk for people, pets or water supply
Arizona Game and Fish Department officials have confirmed the presence of largemouth bass virus in Lake Pleasant.
Lab tests on largemouth bass tissue samples collected during a routine survey in October by Arizona Game and Fish and U.S. Fish and Wildlife Service personnel showed presence of the disease in some samples.
While the virus can affect largemouth bass, it doesn’t pose a risk to people and pets, and the water is safe for drinking water supply and recreation.
“Largemouth bass virus is not known to infect any warm-blooded animals, and any fish that are caught by anglers are safe to eat,” said Marc Dahlberg, Game and Fish water quality program manager. “However, we always recommend that people thoroughly cook any fish they intend to eat, and never use fish found dead or dying for food.”
Game and Fish has not documented any fish kills at Lake Pleasant associated with largemouth bass virus to date. At this time, fishing is still very productive and there have been no recreational impacts. Lake Pleasant is the top fishing recreation site in Arizona, producing more than 520,000 angler use days.
Prior to this sampling, the only fish health survey that had been conducted at Lake Pleasant was in 2002, and largemouth bass virus was not detected then. Therefore, the virus most likely entered the Lake Pleasant fishery within the past 10 years.
Dahlberg explained that although the virus can cause mortality in largemouth bass, not all bass become infected, and not every fish becomes sick. For instance, only five lakes in Texas suffered fish kills even though the virus was found in 23 of the state’s reservoirs.
“Usually the number of infected fish that die is relatively low compared to the entire population, with the virus mostly affecting older and larger fish,” said Dahlberg.
The virus has been found in 18 states dating back to 1991. In Arizona, Saguaro Lake, Bartlett Lake, Roosevelt Lake, and now Lake Pleasant have tested positive for the disease. There have been no impacts attributable to largemouth bass virus at Saguaro, Bartlett or Roosevelt to date.
Although other fish species can carry the virus, it only affects largemouth bass. It is not precisely known what triggers the activation of the virus into a disease outbreak, but it has been associated with stress events, such as high water temperatures. The virus appears to diminish over time.
The Arizona Game and Fish Department emphasizes that there are precautions the public can take to help stop the spread of the virus, as well as other aquatic invasive species, such as quagga mussels. One preventive measure that is vital is that people absolutely avoid transporting live fish or water from one body of water to another.
“You might be spreading an unwanted disease or even introducing an unwanted organism, such as quagga mussels, that could substantially affect a fishery or lake ecosystem,” said Dahlberg. “Don’t transport live fish caught from a lake – period. It’s the wrong thing to do and it’s unlawful.”
It’s also important to clean, drain and dry your boat before leaving any lake at any time, and to disinfect your boat or wait at least five days before launching your boat on another water. In fact, at several lakes, including Lake Pleasant, it’s now the law that you do so. This is extremely important, as the bass virus can live for up to seven days in standing water.
Other ways anglers and boaters can help stop the spread of aquatic invasive species:
- Dispose of all unused bait in the trash, never in the water.
- Never transfer live fish from one body of water to another.
- Rinse any mud and/or debris from equipment and wading gear.
- Drain any water from boats, bilge, bait buckets, and livewells before leaving the launch area. A mild mixture of bleach and water can be used to disinfect your equipment. Allow everything to air dry before moving to another body of water.
- If you see any dead or dying fish, please report your observation to Arizona Game and Fish at (623) 236-7257.
- Educate others to follow these steps.
More information on largemouth bass virus is available at:
Logo courtesy Arizona Game and Fish