Science Spotlight

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  • August 8, 2018

Map of area around Los Padres National Forest, showing where the bear tilapia
This CDFW map shows the routes
and distances traveled by both bears
since being re-released in January.


A light brown bear with a black muzzle sits on a green tarp in the bed of a navy blue pickup truck.
The older bear, safely on her way
back to the wilderness after being
tranquilized in Montecito by a wildlife
officer on April 2. (CDFW photo)

We have an update on the two black bears that were burned in the Thomas Fire in late December/early January! Both bears were suffering from extensive burns to their paws when they were brought to CDFW’s Wildlife Investigations Lab in northern California. Under the care of CDFW Senior Wildlife Veterinarian Dr. Deana Clifford and Dr. Jamie Peyton of the UC Davis Veterinary Medical Teaching Hospital, the bears were given an unusual experimental treatment involving the use of sterilized tilapia skins as bandages. After the bears were well enough to survive on their own, they were returned to the Los Padres National Forest, as near as possible to where they were originally found. Both have covered many miles and each has been spotted at least once since their release.

The younger bear was seen in an avocado orchard on May 29 by a biological consultant conducting a bird nesting survey. The bear ran away, which is a good sign that she has not become habituated. The consultant was able to get photos and video of the bear, who appears to be in good physical shape.

The older bear, who was pregnant during treatment and at the time of her release in January, came down from the hills and wandered into the town of Montecito on April 2. A local wildlife officer tranquilized her and returned her to suitable habitat, and she’s stayed away from people ever since. Though she was reportedly in good general health, there has been no sign of a cub, so the pregnancy may not have been carried to term or the cub may not have survived.

GPS collars on the bears allow CDFW biologists to track the animals’ movements so they can see where each one has been. Data shows the younger bear usually stays near Fillmore, but has made the 10-mile trek back to her release site in the Sespe Wilderness Area at least three times. She also made a brief trip over to Highway 5, north of Castaic. The older bear spends most of her time in the hills above Ojai. “We are encouraged and so pleased that both bears have survived for eight months now after burn treatment and release – they have walked hundreds of miles on their treated feet by now,” Dr. Clifford said.

CDFW will continue to monitor the movements of both bears via their satellite collars for at least another year. The data will ultimately help scientists build their knowledge of how animals utilize landscapes affected by large fires.

Read the original story of the Tilapia Bears at: https://tinyurl.com/y849mru7

Top photo: The younger of the two bears, as seen in an avocado orchard on May 29. (Photo by Jessica West)

Categories: General
  • November 21, 2017

Three men brush a white epoxy on a 600-foot-long by 5-foot wide concrete channel
Working late, Mojave River hatchery staff apply FDA-certified epoxy coating to hatchery rearing ponds.

a tank truck parked next to a concrete fish hatchery raceway with palm trees in background
CDFW fish transportation truck at Fillmore Hatchery

An African American man in a California Fish and Wildlife uniform squats to read something on a low concrete wall at a fish hatchery
Acting Mojave River Hatchery Manager Forest Williams at work

Seven people watch fish come out of a 10-foot pipe from a CDFW tank truck, into a root beer-colored river
A hatchery crew releases trout into the Feather River

view from river-level of water and fish pouring from a tank truck, through a pipe
A fishy view of trout planting on the Feather River

The beginning of trout fishing season in Southern California is just around the corner, and CDFW biologists and hatchery staff are striving to maximize hatchery trout availability for the many anglers who will cast lines in coming weeks. Trout angling in lower-elevation waters of Southern California generally begins in November and continues through April, to correspond with colder water temperatures that can sustain stocked trout.

Precise temperatures are just one of the criteria that must be met before trout stocking begins. Currently, these conditions are approaching optimal levels, but CDFW is running about two weeks behind schedule due to unforeseen circumstances at Mojave River and Fillmore trout hatcheries, two of CDFW’s southernmost facilities.

The Mojave River Hatchery, built in 1947, raises and stocks a ten-year average of 340,000 pounds of catchable trout per year. Beginning in June of this year, extensive maintenance and facility upgrades necessitated turning off the water for a six-month period. While the completed upgrades will ultimately result in better and more efficient trout production for Southern California, the project ran about two months behind schedule. Water is scheduled to flow again at Mojave River Hatchery in late November and the hatchery will be populated with fingerling trout for fast growth. Mojave’s year-round water temperatures yield fast trout growth resulting in maximized yield in minimal time.

While the Mojave River Hatchery was closed, Fillmore Hatchery, built in 1941 on the Santa Clara River, experienced a significant loss of trout inventory intended for Southern California angling due to gas bubble disease. Gas bubble disease is a result of supersaturated gasses (oxygen, nitrogen and carbon dioxide) present in well water pumped from a deep aquifer. While Fillmore Hatchery is equipped to aerate this water and make it suitable for trout, an unknown variable (possibly a drought-depleted and then recharged aquifer) overwhelmed that ability. In an average year, Fillmore Hatchery produces about 400,000 trout for lakes and streams in Southern California. To reduce fish losses from gas bubble disease in the last several weeks, catchable fish were stocked from Fillmore to appropriate waters, and some fish were transferred to other hatcheries. Ultimately, the gas bubble disease at Fillmore resulted in a loss of about 50 percent of inventory. While emergency measures taken by Fillmore staff and

CDFW fish pathologists resulted in better conditions and lower gas super-saturation, the hatchery must be depopulated so that the issue can be addressed entirely. As soon as all trout are removed, hatchery staff and scientists will increase the gas diffusion capability of aeration towers at Fillmore, in order to handle supersaturated well water for the short and long term.

The status of these two hatcheries presented a substantial problem for trout stocking in Southern California that was solved in part by hatcheries in Central and Northern California. These hatcheries have sufficient catchable size trout to supply Southern California’s approved waters immediately and in coming weeks. Thanks to strategic planning and trout production at a statewide level, Northern and Central California can supply fish to Southern California without impacting originally scheduled trout releases in their respective areas.

Trout stocking for Southern California waters will begin this week and hatchery trucks are on the move. Hatchery staff will work quickly to distribute trout to as many approved waters as possible. Trout stocking to Southern California will initially be lighter than usual, but will likely pick back up in 2018. As Mojave River Hatchery comes back online, fish transferred to that facility will be fed and reared to maximize daily growth. We anticipate another large batch of catchable trout available for Southern California toward early spring 2018.

Hatchery staff will be doing everything possible, statewide, to maximize trout production and releases to approved waters in the coming months. Staff work diligently for the angling public and appreciate their continued support.

The statewide planting schedule is updated in real time online.

CDFW photos. Top: Steelhead trout at Mokelumne River Hatchery

Categories: General