Frequently Asked Questions about Aquatic Restoration


Why are fish being removed from certain lakes in Yosemite National Park?

The primary reason fish are being removed from a small number of lakes is to provide more breeding and overwintering habitat for the recovery of the federally endangered Sierra Nevada yellow-legged frog. In addition, the restoration of mountain lakes to a fishless condition benefits ecosystem function as a whole, increasing insect diversity and abundance, which in turn benefits terrestrial wildlife species. A great body of scientific research supports that restoration activities work and that frog populations respond favorably following the removal of non-native fish. \

How are fish being removed from lakes in Yosemite National Park?

Restoration staff are using gillnets and backpack electro-fishing equipment to remove non-native fish. No chemical methods for removing fish are being used at this time.

What do you do with fish that are removed?

Deceased fish that are removed via gillnets or electro-fishing are deposited back into the lake that they were caught from. The lakes in Yosemite’s high country are under ice for over half of the year, meaning that they are often low productivity and experience a very short growing season. It is important for the lake’s ecological community that nutrients garnered in the lake return to the lake for cycling.

Are you trying to remove fish from the whole park?

No. Yosemite is dedicated to providing high-quality fishing experience to visitors who value this activity in the numerous sites throughout the park where fish are not being removed.

How many lakes and streams will be affected by the fish removal restoration project?

Yosemite has almost 2,700 lakes, of which about 250 are known to contain fish. The National Park Service anticipates removing fish only from approximately 25 lakes (about 10% of lakes containing fish) over the next 15 to 20 years. In addition, there are approximately 1,200 miles of streams in Yosemite of which 800 miles are known to support fish. There are no plans to remove trout from stream locations other than short segments associated with lake inlets and outlets at restoration sites.

I have heard of sites that were great fisheries years ago, but now support no fish. Is the National Park Service responsible for removing fish at these lakes?

Some lakes have reverted to a fishless state naturally after the cessation of fish stocking due to poor spawning habitat. Many lake fish population declined naturally following the decision to end all fish stocking in Yosemite National Park.

Where can I find places to fish in Yosemite National Park?

Many local angling guides and fly shops have excellent tips on where to fish and can suggest the best lures/flies to use at each time of the year. Many books are also available where similar information can be gleaned.

Learn more about Yosemite's fishing regulations.

What kinds of sport fish are in Yosemite?

Yosemite’s waterways and/or lakes support many sport fish including: Brook trout, Rainbow trout, Golden trout, Brown trout, and Kokanee salmon. By far, the most abundant fish in Yosemite is the Brook trout.

What is the status of the Sierra Nevada yellow-legged frogs?

The Sierra Nevada yellow-legged frog was once the most abundant amphibian in the high mountain lakes in the Sierra Nevada. Today, the frog is one of the most critically endangered amphibians in North America, having disappeared from more than 95% of their historic sites. Because of their declines, the frog is listed as Endangered under the Federal Endangered Species Act, and is considered a Species of Special Concern by the State of California.

What is causing the Sierra Nevada yellow-legged frog decline?

The primary factor implicated in the decline of the frog is the introduction of fish into a majority of large, deep lakes and into streams in the Sierra Nevada. Fish prey on all life stages of the frog and compete with the frog for food resources. The presence of non-native fish in large, deep lakes, limits remaining frog populations to sub optimal lake/pond habitats. The presence of non-native fish in streams displaces frogs from living in these streams and also severs the use of the stream as a dispersal corridor. In combination, the presence of non-native fish limits frog population numbers by limiting available, high quality habitat and isolates populations from each other.

The second factor negatively affecting the frog is an amphibian fungal disease caused by the fungus Batrachochytrium dendrobatidis, also known as “chytrid. Chytrid has been spreading across the Sierra Nevada since the 1970s, causing extinctions of hundreds of Sierra Nevada yellow-legged frog populations as well as the extinction of many amphibians worldwide. The fungus has infected most Sierra Nevada yellow-legged frog populations in Yosemite National Park, and researchers are studying the persistence of infected populations [1 MB PDF]. Creating habitat for the persisting populations of Sierra Nevada yellow-legged frog by removing the fish humans introduced into their habitat is critical for the recovery of this endangered amphibian.

Why are the Sierra Nevada yellow-legged frogs important?

These frogs are a vital link in energy and nutrient cycling in both the aquatic and neighboring terrestrial ecosystems—they are a top predators feeding primarily on insects and they are an important prey for native birds, snakes, and mammals.

Interestingly, these frogs specialize at living in high elevation environments that tend to have short ice-free seasons for growth. Sierra Nevada yellow-legged frogs can take up to 3 years to metamorphose from a tadpole to a frog, overwintering as a tadpole in lakes underneath the ice! They can take an additional 3 years to grow large enough to begin breeding.

How do I express concerns and learn more about the fish removal program?

Contact Yosemite National Park's Aquatic Ecologist.

Last updated: October 25, 2022

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