Restoration of Native Species in High Elevation Aquatic Ecosystems

Mountain yellow-legged frog

NPS Photo

Staff at Sequoia and Kings Canyon National Parks (parks) have been designing a plan that would help restore native species in high elevation aquatic ecosystems, including selected lakes, ponds, streams and marshes found above approximately 6,000 feet. These ecosystems include the range of two formerly abundant native amphibian species, the Sierra Nevada yellow-legged frog and southern mountain yellow legged-frog (hereafter collectively referred to as MYLFs). Subject matter experts from inside and outside the National Park Service (NPS) are evaluating possible tools, best practices, and public comment to develop alternatives that best meet ecosystem management objectives.

Draft Purpose of and Need for the Plan
The purpose of this Restoration of Native Species in High Elevation Aquatic Ecosystems Plan and Draft Environmental Impact Statement (plan/DEIS) for the parks is to guide management actions by the NPS to restore and conserve native species diversity and ecological function to selected high elevation aquatic ecosystems that have been adversely impacted by human activities. The Final Restoration Plan/FEIS would be implemented over a period of 25-30 years, with re-evaluation scheduled to occur every 5-10 years.

This Restoration Plan/DEIS is needed to provide long-term management direction to restore and conserve the parks' high elevation aquatic species and ecosystems. This action is needed at this time:

• because non-native fish have severely disrupted biological diversity and ecological function;
• to prevent the extinction of mountain yellow-legged frog populations in these parks;
• because current management actions can restore only limited habitat; other management strategies need to be considered because large scale restoration of more complex habitat (large areas containing clusters of lakes with many long and/or complex associated streams) is critical for ecosystem recovery; and
• to enable the NPS to fulfill its mission and policy requirements to conserve native animals, plants and processes found in the parks' aquatic ecosystems.

One example of urgent conservation need is that MYLFs have disappeared from 92% of historic localities in the Sierra Nevada including the parks. Extensive research has identified two primary causal factors for this decline. First, the presence of non-native fish prey on MYLFs, compete with them for food, restrict their breeding to marginal, shallow habitat and fragment remaining populations. Second, the recent spread of disease (chytrid fungus) has infected and imperiled most remaining MYLF populations. In addition, air pollution may be stressing MYLFs, and global climate change has begun to dry up critical MYLF breeding habitat.

Because of the historic abundance of MYLFs, they are important contributors to energy and nutrient cycling in aquatic and adjacent terrestrial ecosystems. Therefore, the MYLFs' decline has had negative consequences to high elevation ecosystems across the Sierra Nevada. Wherever non- native fish are eradicated, it would have beneficial effects to native species and ecosystems. Eradicating fish from waters adjacent to existing MYLF populations would not only restore native ecosystems but would also potentially prevent the extinction of these native species that are integral to ecosystem health.

NPS Management Policies 2006 directs parks to implement feasible management actions to respond to resource threats. As park management and staff have gained a better understanding of high elevation aquatic ecosystems and potential threats to them, it was determined that a comprehensive plan is needed to evaluate and respond to harmful changes in these systems. Some of these changes may be the result of factors outside the direct control of park management (for example: global climate change, air pollution, and disease). However, other changes are the result of human actions in the parks and are within the ability of the NPS to mitigate (such as non- native fish). This Restoration Plan/DEIS is needed to provide guidance for restoration and conservation of native species and high elevation aquatic ecosystems in the parks. Implementation would remove a major threat (non-native fish) from selected ecosystems, improving the resistance and resilience of these systems to unprecedented threats, particularly accelerating climatic change.

Recent Aquatic Management Actions in the Parks
From 1997 to 1999, researchers experimentally used gill nets to eradicate non-native fish from three lakes in the parks, which showed that fish eradication was feasible. In 2001, the parks began to implement preliminary (experimental) restoration of MYLFs. The primary goal was to assess the feasibility of parks staff using gill nets and electrofishers to eradicate non-native fish from low- to moderate-use individual lakes having short associated streams. The purpose of the program was to restore aquatic habitat for native species, with an emphasis on improving the status of imperiled MYLFs.

By 2010, fish were fully eradicated from eight lakes and nearly eradicated from three lakes, and MYLFs in nine of these lakes remained disease-free three years after fish removal. During this time average tadpole density in these nine lakes increased by 13-fold (from 2.4 to 30.8 per 100 ft of shoreline), while average frog density increased by 14-fold (from 2.4 to 33.8 per 100 ft of shoreline). Several of these MYLF populations are now among the largest in the Sierra Nevada. In addition, significantly more garter snakes were detected per survey in fish-removal lakes (0.15) versus fish-containing lakes (0.02). Snake detections also increased over time, exhibiting a positive linear relationship with the number of years since fish removal began. These results show that using parks staff to eradicate non-native fish using gill nets and electrofishers is feasible, and beneficial to MYLFs and other native species. Non-native fish eradications are currently in progress in seven waters, and scheduled to be initiated in 2012 in five waters.

Conceptual alternatives developed thus far for the Restoration Plan/DEIS propose removing non- native fish from up to 83 (15%) of the parks' approximately 547 high elevation lakes, ponds and marshes known to contain fish. This would keep ample opportunities available for recreational fishing while helping populations of MYLFs and other native species become as resilient as possible to uncertain future conditions in several selected basins across the parks.

 

Project Resources
Selected Literature References (pdf, 71 KB)
Aquatic EIS Project Page within the NPS Planning, Environment, and Public Comment System (PEPC)

Related Legislation, Laws, Policies, Guidance & Plans
Enabling Legislation
Organic Act of 1916
Endangered Species Act
Wild and Scenic River Act 1968 (pdf, 107 KB)
Wilderness Act of 1964
General Management Plan
Natural Resources Management Plan
NPS Management Policies, 2006 (pdf, 2 MB)
Preliminary Restoration of Mountain Yellow-legged Frogs Environmental Assessment, 2001