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Population Monitoring of Fisheries in the SW Jemez Mountains

A narrow stream meaders through a grassy meadow surrounded by rock spires.
The East Fork Jemez River flows across Valle Grande and out of the Preserve near its southwestern boundary.

NPS/L. Ray

With miles and miles of meandering mountain streams, Valles Caldera National Preserve is an angler's paradise. It is also an incredibly important watershed protection area. Two primary streams - San Antonio Creek and the East Fork Jemez River - flow across Valles Caldera from east to west, eventually joining courses outside of the Preserve's southwestern boundary and later flowing into the Rio Grande.

San Antonio Creek is approximately 30.5 miles long, and more than 60% of its total course flows within the Preserve. The East Fork Jemez River is approximately 21.5 miles long, and about 42% of its course flows within the Preserve. These streams provide habitat for seven fish species:

Native Fish

  • Rio Grande Chub – “At-risk”
  • Rio Grande Sucker – “At-risk”
  • Longnose dace
  • Fathead minnow – uncertain native
  • Rio Grande cutthroat trout – extirpated native

Non-native Fish

  • Rainbow trout – Introduced game fish
  • Brown trout – Introduced game fish

Electrofisheries monitoring began at Valles Caldera National Preserve in 2003 to track the abundance and distribution of these species in Valles Caldera's streams. The data collected helps scientists monitor restoration efforts and recovery from the effects of historic logging and grazing, recent wildfires, and potential impacts from ongoing recreational fishing.

Fish Populations by Stream, Fall 2019

Populations of fish species within twelve stream reaches in the Jemez Mountains, fall 2019.

Historic black and white image of hundreds of sheep grazing in a grassy valley surrounded by wooded hills.
Sheep herding in the Jemez Mountains, 1935.

Photo courtesy of Dan Scurlock

Riparian and Wetland Restoration

Historically, wetlands were more common at Valles Caldera than they are today. Nearly 150 years of livestock grazing, road construction, mining, and logging during the 19th and 20th centuries led to wetland degradation and loss.

Oral history accounts suggest that there were sometimes up to 100,000 sheep grazing at one time on the Baca Location (present-day Valles Caldera) in the early 1900s. Livestock in those numbers could trample and compact the soils beside streams, causing erosion, sedimentation, and unnatural channelization of waterways.

In addition to livestock grazing, by 1963, logging operations had cut more than 25,000 acres (10,000 ha) of timber from the Baca Location, including 15,000 acres (6,000 ha) of Ponderosa pine and 10,000 acres (4,000 ha) of spruce-fir and mixed conifer stands. The loss of forested areas means a diminished physical buffer against storm water, which can lead to high-severity flooding, soil erosion, and sedimentation of streams.

Since this land's federal acquisition in 2000, restoration efforts have improved wetland quality and extent. Valles Caldera National Preserve is a landscape in recovery, and these studies can help resource managers determine the best course of action to restore ecosystem function and services.

Jaramillo Creek Recovery

Historic black and white photo of sheep grazing along Jaramillo Creek Historic black and white photo of sheep grazing along Jaramillo Creek

Left image
Sheep grazing along Jaramillo Creek, early 1900s

Right image
Jaramillo Creek recovering from grazing impacts, early 2000s

Following 19th and 20th century livestock grazing, road construction, logging, and mining operations, Valles Caldera is a landscape in recovery.

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Valles Caldera National Preserve

Last updated: January 12, 2023