More tests to come, but virus primary suspect

People visiting and living in Lake Havasu have been witnessing the sight of dead carp at the lake, and the problem isn’t likely to quickly vanish.

Arizona Game and Fish Department biologists believe the Koi Herpes Virus (KHV) that killed thousands of carp in Lake Mohave, is the same culprit for the die-off at Lake Havasu. However, there will likely be additional testing next week to confirm this fact. A timeline for final results from the testing is unknown.

The KHV – which can impact carp as water temperatures warm in late spring – impacts gill function and can lead to suffocation and/or secondary infections in carp, koi, and goldfish. While there were some bacterial issues with the Lake Mohave carp, lab tests from the Washington Animal Disease Diagnostic Lab indicated KHV was the primary cause of the die-off.

KHV is not a threat to public health, and it does not affect other wildlife. Recent rumors of other species dying off are unfounded at this point in time.

“Just like with any living thing, fish die,” said Zen Mocarski, information and education program manager with the Game and Fish Kingman office. “There have been other species found along the shoreline, but those numbers represent only the normal amount that would be found at any given time.”

KHV is viewed as the likely cause of the die-off at Lake Havasu because carp remain the only species impacted and Lake Havasu is downriver from Lake Mohave, where this event originated. Locations downriver from Lake Havasu may be impacted as this virus runs its course through the river system.

“While this is not viewed as a public safety threat, anglers should probably focus on fishing for other species the lake has to offer, and people handling the dead fish along the shoreline should take precautions, such as wearing gloves,” said Andy Clark, fisheries program manager for the Game and Fish Kingman office. “This is the case when handling anything that’s died.”

The die-off, Clark said, is not associated with a water quality issue, which would have impacted all species of fish in the lake.

In the middle of May, carp began washing up on shorelines along Lake Mohave and within a week the numbers began to multiply. Shortly afterward, a small number of carp were found dead at Lake Havasu. That number ballooned in recent days and dead fish have littered the shoreline, with the locations driven primarily by prevailing winds.

The Bureau of Land Management (BLM) and Arizona Game and Fish biologists have monitored the shoreline at Lake Havasu and have observed the same traits associated with the die-off at Lake Mohave: white spots along the sides of the gills and a lack of blood in the gills.

While the die-off at Lake Mohave has slowed and provided National Park Service an opportunity to clean dead fish from developed areas such as Cottonwood Cove and Katherine’s Landing, the duration of the die-off at Lake Havasu remains unknown primarily because of water temperatures.

“There’s really no way to know for sure,” Clark said. “I hesitate to make predictions with an issue for which we have no control. Even after the peak of the die-off has passed, it’s highly probable dead carp will continue to wash up on shorelines in smaller numbers.”

Clark added that there’s little that can be done to stop the die-off.

“There’s no method in place to change the water temperature in a short period of time that might slow or stop this event.”

This means residents and visitors have had to deal with an unpleasant sight and smell.

“There’s little that can be done when we start talking about these numbers,” Mocarski said. “While BLM and Arizona State Parks have worked to keep their segments of the shoreline clean, more carp are washing up each day.

“This situation is unique in its scope. My guess is that this will follow a similar course as Lake Mohave, but there’s really no way to tell because water temperatures are such a critical aspect with this disease.”

For fishing information, please check the Game and Fish website, www.azgfd.gov for the latest fishing report.