Eagle Lake trout (''Oncorhynchus mykiss aquilarum'') is a subspecies of

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Eagle Lake, in

Lassen County, California Lassen County ( ) is a county located in the northeastern portion of the U.S. state of California. As of the 2020 census, the population was 32,730, and was estimated to be 28,340 in 2024, Its county seat and the largest city is Susanville ...

. It is a type of

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

known for its ability to withstand high

alkalinity Alkalinity (from ) is the capacity of water to resist Freshwater acidification, acidification. It should not be confused with base (chemistry), basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength of a buffer s ...

.http://stevenojai.tripod.com/elrain.htm Eagle Lake Rainbow Its unique adaptations to the harsh environment of Eagle Lake make the fish a specialist with a very narrow environmental specificity. The Eagle Lake Trout is a State Species of Special Concern, but not considered endangered according to the Federal Endangered Species Act.

Range

The ''Eagle Lake trout'' name comes from its former exclusive-endemic Eagle Lake territory. Eagle lake is approximately 24,000 acres, making it one of the largest natural lakes in

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. The streams and rivers that reach the lake only connect with the lake in the late spring after the snowmelt. The lake is highly basic, with an alkalinity of pH 8-9, making it uninhabitable for many aquatic species. The Eagle Lake trout have adapted to this high pH. While formerly only in Eagle Lake, the Department of Fish and Wildlife (formerly the Department of Fish and Game) has transplanted the Eagle Lake trout into dozens of other lakes in California.

Characteristics

The Eagle Lake trout has a pink horizontal band, white rimmed fins, and irregular spots across its body which become less prolific towards the belly. Large square-shaped tales, large eyes, and a large body give the fish a predatory advantage in the lake. On average the fish is about 18 inches long and 2 pounds, but they have been found to get as big as 28 inches and 10 pounds. Eagle Lake rainbow trout are

invertivore Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγε ...

s and

piscivore A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted repti ...

s. As young, they mainly eat

leech Leeches are segmented parasitism, parasitic or Predation, predatory worms that comprise the Class (biology), subclass Hirudinea within the phylum Annelida. They are closely related to the Oligochaeta, oligochaetes, which include the earthwor ...

es,

amphipods Amphipoda () is an order (biology), order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphip ...

, and

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

. As they mature, the trout consume

tui chub The Tui chub (''Siphateles bicolor'') is a species of freshwater Actinopterygii, ray-finned fish belonging to the Family (biology), family Leuciscidae, which includes the daces, chubs, Phoxinus, Eurasian minnows and related fishes. This fish is ...

fish.

FMIB 38978 Salmo aquilarum Type Eagle Lake trout

Eagle Lake rainbow trout naturally spawn in Pine Creek which runs into Eagle Lake. The young trout spend the first one to two years of their life in the upper regions of the stream before swimming down into Eagle Lake. The natural environment of this

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

is shaded and gravelly. This natural spawning process is now almost wholly eradicated.

Human uses

The Eagle Lake rainbow trout play a significant role in the economy of the region around Eagle Lake. The fish attracts anglers who support the local economy. The Lake allows for the use of

trolling In slang, a troll is a person who posts deliberately offensive or provocative messages online (such as in social media, a newsgroup, a internet forum, forum, a chat room, an Multiplayer video game, online video game) or who performs similar be ...

float tube A float tube, also known as a belly boat or kick boat, is a small, lightweight inflatable fishing craft which anglers use to fish from. They were originally doughnut-shaped boats with an underwater seat in the "hole." Modern designs include a V- ...

pontoon boat A pleasure boat with two lengthwise pontoons A pontoon boat is a flattish boat that relies on floats to remain buoyant. These pontoons (also called ''tubes'') contain much reserve buoyancy and allow designers to create large deck plans fitted w ...

s, and bait and

fly fishing Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...

. The trout are also meaningful and culturally important to the native Paiute people.

Environmental threats

The Eagle Lake Trout face competition with the invasive

brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae native to Eastern North America in the United States and Canada. Two ecological forms of brook trout h ...

, which first came to Eagle Lake in the 1940s. These invasive trout have taken over and damaged the habitat of important spawning locations.

Logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksagriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

, anthropogenic water usage,

railways Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in tracks, which usually consist of two parallel steel rails. Rail transport is one of the two primary means of land transport, next to roa ...

, and

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

s also all contribute to the

habitat degradation Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

that poses a threat by blocking off the natural

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...

of Eagle Lake and its tributaries. Further barriers have made Pine Creek, the location of Eagle Lake trout spawning, inaccessible. Furthermore,

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

leading to

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

and rising temperatures pose threats to the Eagle Lake ecosystem and the health of the Rainbow trout. View of Eagle Lake Facing South

History of conservation

The Eagle Lake Trout spawn in Pine Creek, the creek which runs into Eagle Lake from the Western shore. In the 1930s and 1940s, the Eagle Lake Trout population faced a massive decline due to low water levels, habitat degradation, and overfishing. By the 1950s, in an effort to replenish the trout population, a

weir A weir or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the water level. Weirs are also used to control the flow of water for outlets of l ...

was installed in Pine Creek which captured the trout on their spawning migration. The Eagle Trout were bred in California state

hatcheries A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish, poultry or even turtles. It may be used for ''ex situ'' conservation purposes, i.e. to breed rare or endangered species under controlled ...

and eventually released back into Eagle Lake. In 2012, the weir was modified and now allows the Eagle Lake trout partial entry to Pine Creek for natural reproduction. Currently, the Crystal Lake Hatchery program releases around 200,000 fish to Eagle Lake every year. Still, modern day conservation focuses on developing a self-perpetuating population. Efforts include creating livestock-free areas, removing invasive species, and taking out

culvert A culvert is a structure that channels water past an obstacle or to a subterranean waterway. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe (fluid conveyance), pipe, reinforced concrete or other materia ...

s that reroute Pine Creek. Young, naturally spawned Eagle Lake rainbow trout have recently been discovered in Pine Creek, marking a massive success for the Eagle Lake trout

conservationists The conservation movement, also known as nature conservation, is a political, environmental, and social movement that seeks to manage and protect natural resources, including animal, fungus, and plant species as well as their habitat for the ...

. Still, the species is not yet fully

sustainable Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...

and conservationists continue to work to ensure the future of the Eagle Lake Rainbow Trout.

References

{{Taxonbar, from=Q5325155 Oncorhynchus Trout, Eagle Lake Trout, Eagle Lake Trout, Eagle Lake Natural history of Lassen County, California Fauna without expected TNC conservation status