Science Spotlight

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  • June 22, 2021
monarch butterfly on a milkweed leaf

A male adult monarch on a milkweed leaf
 

Scientist Hillary Sardiñas, who works as CDFW’s pollinator coordinator in the Wildlife Diversity Program, recalls a moment several years ago when she showed her young daughter a monarch caterpillar, and realized it’s a species her daughter might not grow up to enjoy.

“It really hit home in a personal way how important it is to conserve the species,” said Sardiñas.

The population of migratory western monarchs has declined more than 99 percent since the 1980s when millions overwintered in groves along the California coast. By the mid-2010s, the population had dropped to the hundreds of thousands. Just a few years ago, scientists estimated there were only 30,000 left. Now there are only about 2,000 migratory western monarchs left statewide.

“Western monarchs may be headed toward extinction in California, and we need to take drastic and immediate action to help recover the population,” said Sardiñas.

Western monarchs overwinter along the California coast from San Diego to Mendocino County, expanding during springtime along the Central Coast and Central Valley. They ultimately migrate into other states west of the Rocky Mountains to breed.

The drastic population decline has been attributed to several factors including habitat loss, climate change and exposure to pesticides. Western monarchs’ overwintering habitats continue to be destroyed or altered by human development, especially along the Central Coast. Development is also reducing nectar resources. Climate change may be causing monarchs to leave overwintering sites earlier than usual and before milkweed, their host plant, has fully bloomed. This causes what scientists call a “phenological mismatch,” meaning monarchs at times don’t have a place to lay eggs and lack the ability to create the next generation in their multi-generational life-cycle.

In addition to population decline, scientists are seeing a new and possibly dangerous phenomenon—an increase in resident monarchs that remain along the coast year-round and don’t migrate. These monarchs are encouraged to stick around by a non-native milkweed which allows them to breed all throughout the year. The phenomenon might seem like a novel adaptation, but scientists are finding that resident monarchs can have up to 10 times the occurrence of a protozoan parasite known as OE (Ophryocystis elektroscirrha). OE can be transmitted through contact with milkweed leaves, and leads to wing deformation, poor health, decreased reproductive ability or death.

To conserve the population, CDFW is taking action on several fronts:

  • In partnership with the Western Association of Fish and Wildlife Agencies, CDFW helped develop a 50-year management plan for western monarch conservation, published in 2019. Two major focus areas of the plan are management of overwintering sites on the California coast and restoration of breeding and migratory habitat in the Central Valley.
  • In partnership with nonprofit River Partners and with funding from the Wildlife Conservation Board’s Monarch Butterfly and Pollinator Rescue Program, CDFW is restoring and enhancing 500 acres of land for monarchs and pollinators in the Central Valley.
  • On its properties throughout the state, CDFW is enhancing and restoring 1,500 acres of habitat for pollinators and monarchs through management actions and planting milkweed and nectar plants.
  • CDFW is improving management strategies on four department-owned overwintering sites.
  • CDFW is increasing milkweed availability for habitat restoration projects by collecting seed from our properties and partnering with local nurseries.
  • CDFW is also helping coordinate conservation action among stakeholders by participating in the Rangeland Monarch Working Group and co-leading the Monarch Plant Materials Working group with the Xerces Society for Invertebrate Conservation.

Julea Shaw, an environmental scientist in CDFW’s Lands Program, helps coordinate the department’s conservation and restoration efforts. Through her work, she is often reminded how California residents have a personal connection to the western monarch species.

“I speak to so many people who remember growing up seeing thousands of monarchs. It shows how impactful the species can be and how they capture peoples’ imaginations,” said Shaw.

There are several actions that residents can take to help conserve western monarchs.

First and foremost, residents can help by planting locally native milkweed and nectar plants. When choosing nectar plants, conservationists recommend choosing plants that bloom in early spring and late fall when resources tend to be scarce.

Second, residents can help by reducing or eliminating pesticide use in their own gardens.

Third, monarch enthusiasts can help conservation efforts by participating in community science projects. There are multiple organizations which train volunteers to count western monarchs at overwintering sites. In fact, much of the current data on declines in western monarch populations was collected in part by community scientists.

Finally, a note on captive rearing. CDFW would like to remind California residents that a scientific collection permit is required to handle and/or conduct research on western monarchs. Rearing monarchs without proper training can lead to health problems that further exacerbate the species’ decline. Recent research shows that captively reared monarchs can be weaker, have smaller wingspans, and be less adapted to migrate.

“It’s going to take a collective effort between residents and conservation scientists to turn the species around. We’re diligently working to expand our efforts—but the work won’t be done anytime soon,” said Sardiñas.

CDFW Photo

Categories: Science Spotlight
  • June 21, 2021
Scientist, Michael Mammola holding a fish on a lake with blue sky

Michael Mamola, CDFW’s Statewide Trout Management and Stocking Coordinator, shows off a Lahontan cutthroat trout before its release into Echo Lake earlier this spring.

hand holding a fish for release in a lake
The Lahontan cutthroat trout is the largest inland trout species in the world and the only trout native to the Lake Tahoe Basin.

Visitor fishing off the side of a pier in a lake
Few visitors to Echo Lake pause to fish and probe the waters for the Lahontan cutthroat trout that live within.

fish in a lake
Lahontan cutthroat trout grow large in Echo Lake, El Dorado County, thanks to the large population of forage fish, principally the Lahontan redside minnow.

California anglers looking to target the native but elusive Lahontan cutthroat trout may want to put Echo Lake in El Dorado County on their summer itinerary.

For the past several years, the California Department of Fish and Wildlife (CDFW) has managed the deep blue waters of Echo Lake exclusively as a Lahontan cutthroat trout sport fishery.

That’s the same fish that has turned Nevada’s Pyramid Lake and its monster-sized cutthroats into a global fishing destination and created a cult following at Heenan Lake in Alpine County among fly anglers looking to tangle with a trophy cutthroat.

Located just minutes off U.S. Highway 50 near South Lake Tahoe at an elevation of 7,500 feet, Echo Lake may offer California anglers their best chance to encounter the Tahoe Basin’s native trout species given the combination of an easy drive, a plentiful fish population supported through a generous stocking regimen, and wide-open fishing access without the restrictions on seasons, take or tackle methods found at some other Lahontan cutthroat trout fisheries.

Adding to the overall experience, Echo Lake receives relatively little fishing pressure. The 300-acre lake is best known as a jumping-off point for the southern portion of Desolation Wilderness. Few of those backcountry travelers, however, pause to wet a line at Echo Lake.

“It’s sort of a hidden gem,” says Mitch Lockhart, CDFW’s District Fisheries Biologist for El Dorado, Placer and Nevada counties. “You’ll not be combatting for space to fish here.”

Echo Lake received a recent stocking of 100 brood stock Lahontan cutthroat trout from nearby Heenan Lake. Resplendent in their crimson spring spawning colors, the fish ranged in size from two to nine pounds with an average weight of two to three pounds. CDFW followed up that trophy stocking with a plant of some 20,000 “sub-catchable” Lahontan cutthroat trout in the seven- to nine-inch range.

Echo Lake’s recent history as a Lahontan cutthroat trout fishery resulted from a collaboration between lakeside property owners and CDFW. Cabin owners were seeking improved fishing opportunities given recent cutbacks and elimination of hatchery stockings of rainbow trout, brown trout and brook trout. At the same time, CDFW fisheries biologists were looking for suitable locations to stock Lahontan cutthroat trout into their historic range in the Tahoe Basin and expose more anglers to the unique, native fish.

Echo Lake fit the criteria. Its steep-sided granite cliffs, clean, cold deep waters are reminiscent of Independence Lake in Nevada County and Fallen Leaf Lake in El Dorado County, two historic and active Lahontan cutthroat trout fisheries.

Echo Lake also is relatively isolated from other waters and protected from infiltration by non-native trout species. The lake holds some small, remnant populations of brook and brown trout with little opportunity for wild rainbow trout to access the lake and colonize it from surrounding waters. Displacement, hybridization and competition from non-native trout is largely what earned the Lahontan cutthroat trout listing under the federal Endangered Species Act 51 years ago and what mostly prevents large-scale recovery efforts today.

And unlike some other high Sierra lakes where trout eke out a meager existence in near-sterile conditions, Echo Lake is rich with food in the form of the Lahontan redside, a native minnow that has proven an important forage fish responsible for Lahontan cutthroat trout growth rates of two to three inches a year in Echo Lake.

Anglers reported catching Lahontan cutthroats to 26-inches last year with the average size being closer to 12 to 14 inches with an occasional 16-, 18- and 24-inch fish in the mix. CDFW biologists say they are seeing anecdotal evidence of natural spawning, but plan to manage Echo Lake primarily for recreational fishing and not species recovery.

CDFW has stocked two strains of Lahontan cutthroat trout into Echo Lake, the Pilot Peak strain of Pyramid Lake fame that can reach sizes in excess of 20 pounds, and the smaller Independence/Summit Lake strain of fish from eggs collected at Heenan Lake and raised at the American River Trout Hatchery outside of Sacramento.

A Lahontan cutthroat trout caught and documented from Echo Lake qualifies for CDFW’s Heritage Trout Challenge, which incentivizes and rewards anglers for catching six different forms of California native trout from their historic drainages.

In addition to easy drive-to access, Echo Lake features a popular marina, boat launch and convenience store where kayaks and canoes can be rented. Private boats and other waterfcraft can be launched only after mandatory inspection and certification that they are free of aquatic invasive species.

CDFW Creates Lahontan Cutthroat Trout Sport Fishery at Echo Lake (Video)

CDFW Photos:

Categories: Science Spotlight