Saving a Rare Desert Fish on the Brink of Extinction

Pahrump poolfish (Empetrichthys latos) are being kept at the Nevada state fish hatchery, at the Lake Meade National Recreation Area, as restoration efforts to restore their home habitat begin on Lake Harriet, near Las Vegas. Credit: Enrique Villar/USFWS

Recovery Efforts Are Underway to Save the Pahrump Poolfish at Spring Mountain Ranch State Park in Southern Nevada

December 8, 2016

There is a rare species of desert fish fighting for its survival in a fresh water pond in the desert landscape of southern Nevada -- the Pahrump poolfish.

According to biologists monitoring the tiny fish, one of the last remaining populations of the endangered Pahrump poolfish, Empetrichthys latos, is at an alarmingly low number, below 1,000, compared to the 10,000 recorded in 2015.

Go along with biologists James Harter and Kevin
Guadalupe on Lake Harriet, in southern Nevada,
as they work to save the Pahrump poolfish. Click
the YouTube link  to watch in the YouTube App,
or full screen. Credit: USFWS

Throughout the month of October 2016, U.S. Fish and Wildlife Service biologist James Harter and Nevada Department of Wildlife (NDOW) biologist Kevin Guadalupe are rescuing the Pahrump poolfish from Lake Harriett at Spring Mountain Ranch State Park outside of Las Vegas, Nevada, and moving them to the NDOW’s fish hatchery at the Lake Mead National Recreation Area.

The poolfish are being taken to the hatchery to protect the species from extinction.

According to Harter, it is the Service’s intention to “maintain what population currently exists.” The interagency team will then drain the water in Lake Harriet and remove any non-native plant and animal species. The goal is to restore the lake to its original condition before reintroducing the Pahrump poolfish back to the wild.

Biologists James Harter, USFWS, and Kevin Guadalupe, NDOW, check fish traps on Lake Harriet in southern Nevada. Credit: Lora Hendrickson/USFWS

The Pahrump poolfish is a small fish, ranging from one to three inches in length and recognized by its bright yellow fins. They typically live three to five years and do not coexist well with other fish or predatory animals.

Drastic Decline in Numbers

Pahrump poolfish have lived in warm springs of southern Nevada for thousands of years and are considered a native species to this area. The recent steep drop in numbers is due to red swamp crayfish, mosquitofish, household goldfish, and koi fish being unlawfully introduced into Lake Harriett.

Nevada Department of Wildlife fish biologist, Greg Munson, displays a red swamp crayfish caught in the minnow traps used to capture the Pahrump poolfish.  The crayfish is a non-native predator for the poolfish and is a major threat to the fish's survival in southern Nevada.  Credit: Lora Hendrickson/USFWS

The poolfish's adversaries, considered non-native or invasive species, disrupt the ecosystem by eating Pahrump poolfish, their eggs, and their food, which consists of aquatic insects and algae. The devastating effects on the poolfish population are obvious.

“When one owns an aquatic pet, it’s important that people know that they are responsible for it for the lifetime of that pet,” said Guadalupe. “People think that they are saving one fish, but by dumping a non-native species into a lake, they are disrupting an entire ecosystem.”

Rescue and Recovery Efforts

Recent rescue attempts resulted in the capture of 162 poolfish. To collect the fish, biologists place bait inside cylindrical mesh traps. The traps are strategically placed around the lake, allowing the fish to passively swim into them. Individual trap locations are marked with a colorful ribbon and routinely monitored for activity.

Biologists Kevin Guadalupe, NDOW, (left) and James Harter, USFWS (right) document trapping location on Lake Harriet. The team captured 162 Pahrump poolfish in the lake prior to eliminating the remaining nonnative preditors. Credit: Lora Hendrickson/USFWS

Time is essential to the process. If the traps are left unattended for two hours, crayfish sense the bait, get into the trap, and eat the poolfish. The team must also recover the poolfish before the temperature drops. Poolfish thrive in water temperatures above 75 degrees. Below 75 degrees, the Pahrump poolfish go into a hibernated state and become more vulnerable to predators. Once the fish are collected, the team transports them to NDOW’s hatchery at Lake Mead.

Upon collection of a majority of the poolfish population, the team, with the help of the Nevada Division of State parks (NDSP), will drain Lake Harriet and eliminate the invasive species.

Pahrump poolfish at the Lake Meade Recreation
Area fish hatchery. Credit: Enrique Villar/USFWS

Guadalupe and Harter agree that drying up the lake is the safest way to eliminate the predators. After they have completed this process the Service plans to fill the lake and release the Pahrump poolfish back into Lake Harriet - the species’ most successful habitat to date.

Poolfish reproduce year round, which makes them very successful at natural reproduction in a safe and suitable habitat. The Service hopes to see the numbers increase at a healthy rate once the poolfish are returned to Lake Harriet.

Both Harter and Guadalupe feel that it is important for this fish to survive because as a native fish to Southern Nevada, they "contribute to the natural diversity and history of the state."

Additional partners working with the U.S. Fish and Wildlife Service and NDOW include the NDSP, Las Vegas Springs Preserve, the Bureau of Land Management, and private partners. To view the Pahrump poolfish in aquaria, visitors can find them at Spring Mountain Ranch State Park Ranch House and in two tanks at Corn Creek on the Desert National Wildlife Refuge. Both locations are a short distance from the Las Vegas metro area.

Ways To Help The Pahrump Poolfish

The Service and NDOW both express that to help the Pahrump poolfish humans must recognize areas that are set-aside for them. Lake Harriett belongs to the species itself. Do not put pet fish in natural springs.

These two partner agencies are asking the public to spread the message. If you are interested in helping, both agencies encourage volunteering at local state parks and wildlife refuges.

A balance between humans and nature must be found. The Pahrump poolfish is one species that is counting on it.

An oasis in the desert, Lake Harriet is the last remaining habitat for the Pahrump poolfish in southern Nevada. Credit: Lora Hendrickson/USFWS

Pahrump Poolfish History

Pahrump Poolfish is the only surviving form of a genus native to California and southern Nevada. The species has existed for thousands of years surviving in very small fresh water habitats of natural springs.

In the 1950s, the Ash Meadows poolfish went extinct, and in the 1960s, two subspecies of Pahrump poolfish went extinct, leaving only the Pahrump poolfish located at Manse Spring in the Pahrump Valley. By the 1950s, Manse Spring began to fail due to groundwater pumping.

In the 1960s, NDOW and the Service transplanted the remaining Pahrump Poolfish into four other fishless locations in Nevada—Los Latos Pools on Lake Mead Recreational Area, Corn Creek Springs on the Desert National Wildlife Refuge, Shoshone Springs, and White Pine County, Nevada.

Pahrump poolfish was first designated as endangered in 1967 under the Endangered Species Preservation Act and listed under the Endangered Species Act in 1973. In 1980, the U.S. Fish and Wildlife Service officially created a recovery plan to address the threats to the species and move it toward recovery.

In 1989, they were transplanted into Lake Harriett at the Spring Mountain Ranch State Park to provide a secure refuge.

Less than 10 percent of the Pahrump poolfish remain in only a few places in Nevada. The graphic above epxlains the parallel actions being undertaken on Lake Harriet, near Las Vegas, to save the tiny fish.  Credit: USFWS

Nevada Department of Wildlife biologist Kevin Guadalupe displays a red swamp crayfish taken out of Lake Harriet.  The non-native crayfish is a major threat to the poolfish.  Credit: Lora Hendrickson/USFWS