Recent accomplishments of CDFW's scientific community
For more than a century, CDFW’s Trout Hatchery and Stocking Program has been providing recreational fishing opportunities to anglers throughout California. Today, the trout hatchery program is composed of 13 hatcheries, which oversee 20 distinct fish production programs to produce 17 strains, species and subspecies of trout.
McCloud River Redband Trout (Oncorhynchus mykiss stonei) is the latest addition to the CDFW’s production and release efforts. McCloud River Redband Trout is a unique sub-species of rainbow trout endemic to the upper McCloud River area of Shasta and Siskiyou counties of northern California. This fish has beautiful coloration and unique adult characteristics – a pronounced crimson lateral stripe, adult parr marks, relatively large black dorsal spotting, yellow-white hues on the underbelly and white-tipped fins.
The new production and stocking program for McCloud River Redband Trout at Mt. Shasta Fish Hatchery will focus on the upper McCloud River, including McCloud Reservoir. Given that stocking will occur solely within the historic watershed of McCloud River Redband Trout, the program is distinguished by CDFW as a Heritage Trout Production Program. A Heritage Trout is defined as a species of trout native to California, in its native habitat and area. This type of fishery represents the most natural form of aquatic habitat, species and angling opportunity available. Many anglers seeking additional challenges and goals will specifically pursue heritage trout fisheries.
While modern genetics management and conservation hatchery methods are utilized in the McCloud River Redband program, the hatchery-produced fish are primarily for recreational angling and not for release to areas containing wild and genetically pure McCloud River Redband Trout in their natural habitat. This ensures that the most wild populations remain in their native habitat and can continue local adaptation without hatchery influence. CDFW expects the McCloud River Redband Trout program to reach full implementation by 2019-20. The McCloud River Redband program demonstrates CDFW’s progress and commitment to conservation efforts and fisheries management.
CDFW trout hatcheries will continue to produce and stock several strains and species of trout statewide to promote trout angling opportunities, and contribute to the conservation of California’s native species and sub-species of trout. One of the next priorities for the department’s trout hatchery program will commence in 2018, and focus on advancing the Kern River Rainbow Trout program at CDFWs’ Kern River Planting Base.
CDFW Fish and Wildlife Technician Beau Jones stocking McCloud River Redband Trout in August 2017. CDFW photos by hatchery staff.
Pronghorn antelope (Antilocapra americana) were once one of the most numerous large mammals in California, with populations estimated to have been as high as 500,000 prior to the Gold Rush era. In the mid-1800s, pronghorn were nearly extirpated by market-shooting to feed California’s rapidly expanding human population.
The remaining population of pronghorn has long been understudied. Prior data collected on the species have been limited to herd counts and habitat selection. In recent years, there has been growing concern over pronghorn populations, particularly in northeastern California. During the harsh winter of 1992, the number of pronghorn dropped almost 50 percent to an estimated 5,000 individuals. The northeastern portion of the state currently supports a population of approximately 4,500 animals that occur primarily in Modoc, Lassen, Siskiyou and Shasta counties and has been fairly stable, with slow declines, since about 2000. The herd’s inability to rebound has prompted scientists to try to understand the specific conditions leading to the declines.
In 2016 the Institute for Wildlife Studies (IWS) completed a two-year study, with funding from CDFW’s Big Game Management Account, which explored aspects of the pronghorn population on the Modoc Plateau. The study involved 48 does (adult females) and 42 fawns that were radio-collared and followed until their deaths or the study’s end. The researcher’s objectives were to learn more about the pronghorn use of habitat, aspects of their reproduction and factors affecting survival of does and fawns.
The researchers found that for most of the year, pronghorn used open areas with less shrubby and more herbaceous vegetation within their sagebrush-steppe habitats. But during fawning, when does need to hide their young, they shifted to spending more time in areas with greater densities of shrubs and juniper trees. The annual survival rate for does in the study was 69 percent, which is low compared to other pronghorn populations. Mountain lions accounted for 80 percent of predator-related mortalities, most of which occurred during and just after the peak birthing period when does are most vulnerable. Fawn survival averaged 44 percent, a higher-than-typical figure, with unknown causes (37.5 percent) or suspected coyote predation (21 percent) accounting for most fawn mortalities.
The adults’ increased use of shrubby areas and conifer woodlands during fawning suggests an important factor in the population’s continued decline. Juniper woodlands have been encroaching on the sagebrush-steppe habitat in the Modoc Plateau for decades, and these juniper trees provide areas of concealment for ambush predators such as mountain lions. Most ungulate studies demonstrate that adult survival plays a more critical role in population stability than juvenile survival. CDFW may be able to reduce adult pronghorn mortality through habitat restoration – the removal of encroaching junipers could help to reduce predations by lions, and potentially increase the Modoc pronghorn population.
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