Hot Creek Hatchery outbreak threatens fish stocking

A young angler brings home a stocked fish at Crowley Lake. 

 No stocking from local hatchery until fish are healthy again  

The California Department of Fish and Wildlife has suspended all fish planting from the Hot Creek Trout Hatchery after a bacterial outbreak was recently detected at the facility.

There was no estimate as to how long the fish planting would be suspended at press time this week.

Fish pathology experts have confirmed an outbreak of the bacteria Lactococcus garvieae in some trout at the hatchery, CDFW said in a recent news release. The state agency has now quarantined the facility, halted all fish planting, and is preparing to expand testing and vaccinate the fish stocks, they said.

This is not a new disease to local hatcheries; it affected three Southern California and Eastern Sierra hatcheries for the first time last year. The bacteria is not known to cause significant illness in humans if they have consumed fish with the disease (see below) but there have been some instances of illness in some people. 

According to the state, Lactococcus garvieae is the same disease that forced the quarantine and suspension of fish planting last year at three other state trout hatcheries in Southern California and the Eastern Sierra – the Mojave River Hatchery, Black Rock Trout Hatchery and Fish Springs Trout Hatchery. That outbreak ultimately forced the euthanization of 3.2 million trout at those hatcheries, which had a serious impact on the number of fish that were stocked in the region last year.

Hot Creek Trout Hatchery was originally quarantined with the other three hatcheries last year out of caution, but the quarantine was lifted after testing found no evidence of the disease and the hatchery continued to raise trout and stock local waters with those trout – until now.

“Unfortunately, the timing couldn’t be worse with the high visitation this past week due to the holiday weekend and Mule Days,” said Jay Rowan, Acting Fisheries Branch Chief for CDFW last week. “We don’t yet know the extent of the outbreak at Hot Creek Hatchery, but we do have the advantage of some additional tools in our toolbox now versus a year ago, including recently developed vaccines that we started rolling out to fish at the three previously infected hatcheries earlier this month.” 

The outbreak of Lactococcus garvieae, which is similar to streptococcus, has been reported in cattle and poultry farms as well as fresh and saltwater fish and shellfish hatcheries around the world, the state said. 

However, it had never before been detected in fish in California until the hatchery outbreaks last year. 

Fish that are infected with Lactococcus garvieae can show symptoms including bulging eyes, lethargic or erratic swimming and increased mortality, or be asymptomatic and show no signs of infection depending on a several factors including water temperature and stress, CDFW said.

Fish-to-human transmission of this bacteria is rare and unlikely but there are several documented instances associated with immunocompromised people consuming infected raw fish and unpasteurized milk products, they said. 

IF YOU WANT TO KNOW MORE

• For real-time stocking updates, California anglers can refer to CDFW’s Fish Planting Schedule at https://nrm.dfg.ca.gov/FishPlants/. This schedule is updated directly by CDFW hatchery staff. Although it contains current information, all fish plants are subject to change depending on road, water, weather and operational conditions.

• Members of the public can email questions to hatcherybacteriainfo@wildlife.ca.gov

• About Hot Creek Hatchery: CDFW’s Hot Creek Trout Hatchery is located in Mammoth Lakes and raises four species of trout – rainbow trout, brown trout, Eagle Lake trout and Lahontan cutthroat trout – for recreational fishing. Fish from the hatchery are stocked in Mono and Inyo counties.

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