The Crater Lake newt may gain protection under the federal Endangered Species Act if recent efforts by the Center for Biological Diversity prevail.

Even if the newt, also known as the Mazama newt, receives protection under the ESA, studies begun in 2008 by aquatic biologists at Crater Lake National Park indicate it may not be possible to ensure their survival. Unchecked, growing populations of non-native crayfish that feed on newts are “nearly impossible to remove once established,” according to the U.S. National Park Service.

The distinct rough-skinned population of newts is found only at Crater Lake.

Crater Lake park biologists Dave Hering and Scott Girdner are cautiously optimistic the ESA listing will be beneficial.

“We don’t have a good strategy yet,” Hering said. He added, “Maybe additional attention on this problem will help us develop a solution.”

“I don’t think there’s anything we can do to control crayfish currently,” Girdner noted.

Girdner said efforts might focus on collecting and raising newts at another location “with the hope being that some technology might come along in the future to control crayfish” and eventually return Mazama newts to the lake. “It’s an option we’re considering,” Hering agreed, calling it a “stop-gap consideration.”

An earlier report on newts and crayfish noted, “Lessons learned by studying crayfish invasion at Crater Lake National Park may help managers in other areas reduce the spread of this destructive invader.”

Chelsea Stewart-Fusek, an endangered species attorney for the Portland-based Center for Biological Diversity, said a petition requesting the listing was filed Nov. 15 with the U.S. Fish and Wildlife Service. The petition notes that sharp declines in newt populations, with losses estimated at more than 80 percent, stem from the exploding populations of crayfish.

In addition, the petition notes that warmer water temperatures resulting from climate change have resulted in a 5.6-degrees-Fahrenheit increase in summer surface temperature since record keeping began at Crater Lake in 1965. Warmer water temperature gives crayfish more time to move and, according to biologists, appears to allow more crayfish to survive from year to year.

Crayfish population explodes

Despite years of efforts to remove and reduce crayfish populations, their numbers have increased since 2008, when they occupied 50% of the lake’s shoreline compared to 95% today. According to the petition, scientists believe crayfish will occupy the lake’s entire shoreline in two years.

“It’s really bleak,” Stewart-Fusek said of the spiraling numbers of crayfish, which are not native to the lake. “Wherever crayfish are, the newts are not.”

“They’re just getting squeezed out,” Girdner said. He and Hering said they believe the extinction of newts is a concern because a fundamental National Park Service goal is to “preserve natural resources unimpaired for future generations.” Likewise, Stewart-Fusek said, “Every species, I believe, should have the intrinsic right to exist,” a sentiment echoed by Hering and Girdner.

An estimated 15,000 crayfish were introduced to Crater Lake in 1915 as a food source for fish, which also were not native to Crater Lake. The fish were stocked in 1888 to lure fishermen to the lake. Fish stocking continued until 1941. Of the several species introduced, only Kokanee salmon and rainbow trout remain. The fish feed on crayfish, and recent studies show that rainbow trout caught near Cleetwood Cove are heavier and 50 percent longer than in previous years. One trout was found to have 23 crayfish in its digestive tract.

Most adult newts are 4 to 5 inches long. Crayfish and newts are similar in size, but, according to Girdner, crayfish are “much more aggressive than newts and can easily kill and eat a newt if it gets hold of it.”

“Short-sighted actions can have devastating impacts very quickly,” Stewart-Fusek said of the long-term impacts of introducing fish and crayfish.

In recent years, blooms of algae growing on rocks along the shoreline have increased. That’s significant, Stewart-Fusek and others believe, because Crater Lake is one of the world’s deepest lakes and is internationally famous for its water clarity.

Along with threatening to eliminate newts, crayfish consume native invertebrates along the shoreline. Increasing crayfish populations led park aquatic biologists to spend three seasons removing crayfish.

Girdner said more than 5,000 crayfish were captured and removed from the Phantom Ship area over a three-year period but said, “We had no impact.”

Hering terms trapping as “impractical,” noting those efforts have not been “enough to slow the trend” of increased crayfish numbers. Because crayfish are found more than 600 feet below the lake surface, Hering and Girdner believe efforts to control or eliminate them using currently available techniques are not feasible.

A previous NPS report explained, “Although stopping crayfish spread is unlikely, park scientists have continued to study the impact of introduced crayfish so that others may learn from this 100-year-old mistake. Crater Lake is an ideal location for such studies because the lake is protected entirely within a National Park. The effects of crayfish are easier to decipher in the protected area, where they are not complicated by other human-induced changes as is often the case in other lakes (e.g. harvest, water withdrawals, nutrient inputs, hydroelectric fluctuations, forestry, fisheries management, boating, etc.).”

The proliferation of crayfish is also believed to be linked to increased algae outbreaks on rocky shorelines. In 2021, for example, a dense cover of algae along large areas of the lake’s shorelines turned the shoreline bright yellow.

“It was shocking,” Girdner said. “It looked like someone had colored the shoreline with a giant yellow highlighter.”

He said the algae bloom along the shoreline “tended to occur in locations where crayfish occur, likely because crayfish have eaten most of the invertebrates that would otherwise eat algae growing on the rocks, such as snails and caddisflies.”

The petition seeking ESA protection says that “newts in Crater Lake are morphologically, genetically and physiologically distinct from populations of newts outside of the lake.” Stewart-Fusek said if protection for the newt is granted under the ESA, more funding will be provided for crayfish removal efforts and the development of a comprehensive newt recovery plan for the newts.

The U.S. Fish and Wildlife Service has 90 days to determine whether the newts might warrant a listing under ESA. The Center for Biological Diversity has requested that the petition be considered on an emergency basis “due to the imminent threat that introduced crayfish pose to the newt’s continued existence.”

“We don’t expect it to be controversial,” Stewart-Fusek said of the ESA request. “Time really is of the essence.”

Petition outlines newt concerns

The lengthy petition seeking protection for the Crater Lake newt, or Taricha granulosa mazamae, terms it “a distinct population of the rough-skinned newt widely distributed throughout the Pacific Northwest.”

“The Crater Lake newt was first formally described in the 1940s and proposed as a subspecies characterized by unusually dark ventral pigmentation … Genetic analyses of rough-skinned newts confirm that newts in Crater Lake are morphologically, genetically, and physiologically distinct from populations of newts outside of the lake … The Crater Lake newt has a rounded snout, rough skin, and is dark in color on its dorsal surfaces. The ventral surfaces have orange-yellow coloration with dark pigmentation that may have a mottled appearance, and it is this darker ventral color that most clearly distinguishes it” from other newts.

According to the petition, “newt larvae consume plankton and other small aquatic invertebrates” and “historically filled the niche of top aquatic predator in Crater Lake.” But because newts are “highly vulnerable to predation by introduced fish and crayfish; it appears that its only defense to predation by crayfish is to flee … Because it evolved as the lake’s top aquatic predator, the newt lacks predator defense mechanisms; as such, newts require predator-free habitat to remain viable.”

The petition notes Crater Lake aquatic biologists conduct regular monitoring of the lake’s water quality and crayfish distribution but says more funding and studies are needed. “Listing under the ESA would provide the newt with a recovery plan and the long-term funding of conservation efforts that are called for by scientists and necessary for the newt to have any chance of persistence.”