CDFW to Supplement Fish Stocks for Anglers as Bacterial Outbreak Leads to Further Losses at Two Eastern Sierra Trout Hatcheries

Mon, 20 Jun 2022 10:45:31 GMT

Two California Department of Fish and Wildlife (CDFW) trout hatcheries in the Eastern Sierra are continuing to fight an outbreak of Lactococcus petauri, a naturally occurring bacteria that sickens fish. The current outbreak was first detected in April 2022. CDFW fishery managers announced this week that approximately 350,000 infected catchable rainbow trout are now showing signs of disease and must be humanely euthanized.

The affected facilities – Black Rock and Fish Springs hatcheries – usually provide fish for stocking waterways in CDFW’s Inland Deserts Region. Because this is a significant loss of fish that would normally be stocked for anglers in the 2022 season, CDFW is working to contract with an external vendor to provide catchable rainbow trout for planting in Mono County. Approval of this contract is anticipated in July and stocking could begin soon after. In addition, other CDFW hatcheries across the state are supporting the eastern Sierra by providing and stocking fish in priority waters.

“This loss is a huge disappointment, but we were prepared for this possibility and are doing all we can to ensure to continued angling opportunity for the public,” said CDFW Fisheries Supervisor Russell Black. “The fish from the private contractor and stocks from non-infected hatchery facilities will help bridge the gap while we work to vaccinate the remaining stocks at the affected facilities. We are doing all we can to stock as many fish as possible.”

In addition to purchasing fish and redirecting existing stocks, CDFW’s plans to combat the outbreak and improve hatchery capabilities include:

The use of two different types of fish vaccines (immersion and injection) developed by scientists at the University of California, Davis, at the affected hatcheries.
Infrastructure improvements, including the installation of a new recirculation pump at Fish Springs Hatchery, and backup generators at Black Rock Hatchery and Hot Creek Hatchery.
Plans to modernize equipment, vehicles and facilities at other hatcheries throughout the state, both to improve drought resiliency and ensure that hatcheries are prepared to support each other when unexpected losses occur.
Pending proposals for five new hatchery technicians for the Inland Deserts Region, as well as an additional $5 million for fish food, water and electricity for the statewide hatchery system.

Lactococcus petauri occurs naturally in the environment and is usually spread by movement of fish or eggs. CDFW’s fish pathologists believe that it may have been carried into the hatcheries by birds that picked it up from an environmental source. Fish that are infected with the bacterium can show symptoms including bulging eyes, lethargic or erratic swimming and increased mortality, or be asymptomatic and show no signs of infection depending on several factors including water temperature and stress.

Fish-to-human transmission of this bacteria is rare and unlikely. As always, anglers should follow USDA recommendations on cooking fish to an internal temperature of 145 degrees F.

For additional information, please see CDFW’s frequently asked questions about the Lactococcus spp. outbreaks (PDF).

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Media Contacts:
Russell Black, CDFW Inland Deserts Region, (951) 852-6386
Ken Kundargi, CDFW Fisheries Branch, (916) 508-7788
Kirsten Macintyre, CDFW Communications, (916) 849-1714

New Bacterial Outbreak Confirmed at Two Eastern Sierra Fish Hatcheries

Thu, 21 Apr 2022 12:00:52 GMT

Two California Department of Fish and Wildlife (CDFW) fish hatchery facilities in the eastern Sierra have recently detected an outbreak of Lactococcus petauri, a naturally occurring bacteria that sickens fish. CDFW fishery managers are working to implement strategies that will help the facilities get the disease under control, without cancelling all trout plants prior to the traditional season opener on April 30.

The affected facilities – Black Rock Hatchery and Fish Springs Hatchery – usually provide fish for stocking waterways in CDFW’s Inland Deserts Region. Both facilities experienced a similar outbreak of Lactococcus garvieae in 2020, which led to the euthanization of approximately 3.2 million fish in order to stop the spread of disease (L. petauri is molecularly very similar to L. garvieae; the general abbreviation for both strains is Lactococcus spp.).

Earlier this month, the four raceways that hold catchable fish at Black Rock Hatchery tested positive for the Lactococcus bacteria. This accounts for approximately 120,000 trout, which would normally be stocked throughout the fishing season. At Fish Springs Hatchery, all lots of catchable fish (approximately 550,000 trout) tested positive. The current outbreak is among fish that have already received one round of vaccination.

In lieu of depopulating the affected hatcheries, non-diseased fish will be stocked into high-use waters that are hydrologically connected to the affected hatcheries and have cold water. This will mean increased plants for some locations and decreased plants for others. Diseased fish will be euthanized and not planted.

“This is unfortunate timing, as it affects our planting efforts in the weeks before the opener, but all is not lost,” said CDFW Director Charlton H. Bonham. “Fortunately, we learned much from the 2020 outbreak, and we have more knowledge and better tools to fight the bacterium this time around. We also believe we can continue stocking, with some adjustments and careful monitoring.”

Prior to the 2020 outbreak of Lactococcus, which is similar to streptococcus, the bacterium had never before been detected in fish in California, and thus there were no known effective treatments to employ. CDFW put three facilities under quarantine for more than a month, while pathologists and hatchery staff treated the affected fish. CDFW was successful in developing vaccines and continue to work on vaccine-related issues to improve efficiency.

Lactococcus spp. occurs naturally in the environment and is usually spread by movement of fish or eggs. CDFW’s fish pathologists believe that it may have been carried into the hatcheries by birds that picked it up from an environmental source. The current strain of bacteria is identical to one found in fish farms in central Mexico, which lends support to the hypothesis that birds using the pacific flyway are the likely vector for the spread of the bacteria. Fish that are infected with the bacterium can show symptoms including bulging eyes, lethargic or erratic swimming and increased mortality, or be asymptomatic and show no signs of infection depending on several factors including water temperature and stress. Fish-to-human transmission of this bacteria is rare and unlikely. As always, anglers should follow USDA recommendations on cooking fish to an internal temperature of 145 degrees F.

CDFW has initiated a phased priority stocking plan for the eastern Sierra. This plan will focus on planting high-use waters in southern Mono and northern Inyo counties. Similar to measures taken to handle the 2020 outbreak, CDFW will be investigating all available options to secure additional fish for increased planting opportunities, including redirecting fish plants from non-infected hatcheries. Results of the latest testing at Hot Creek Hatchery indicate that the fish in that facility’s upper raceways are cleared for planting at this time.

For additional information, please see CDFW’s frequently asked questions about the Lactococcus spp. outbreaks (PDF).

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Media Contacts:
Russell Black, CDFW Inland Deserts Region, (951) 852-6386
Ken Kundargi, CDFW Fisheries Branch, (916) 508-7788
Kirsten Macintyre, CDFW Communications, (916) 849-1714

CDFW News

CDFW to Supplement Fish Stocks for Anglers as Bacterial Outbreak Leads to Further Losses at Two Eastern Sierra Trout Hatcheries

New Bacterial Outbreak Confirmed at Two Eastern Sierra Fish Hatcheries