biology

Gila trout

Gila trout is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Gila trout rather than just read about it. In short: The Gila trout (Oncorhynchus gilae) is a species of salmonid, related to the rainbow trout, native to the southwestern United States. Prior to 2006 the Gila trout was federally listed as endangered.

Key takeaways

Gila trout belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gila trout to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gila trout from memory before moving on to harder problems.

Reference excerpt

The Gila trout (Oncorhynchus gilae) is a species of salmonid, related to the rainbow trout, native to the southwestern United States. Prior to 2006 the Gila trout was federally listed as endangered. In July 2006, after much work by the New Mexico Department of Game and Fish and Arizona Game and Fish Department, the United States Forest Service and the United States Fish and Wildlife Service, the Gila trout was down-listed to threatened, with a special provision called a "4d rule" that will allow limited sport fishing – for the first time in nearly half a century. By the time the Gila trout was closed to fishing in the 1950s, its numbers and range were so depleted and so reduced this copper-colored trout simply wasn't very accessible to anglers. As of 2011 there is fishing in both states for this fish.

Range The Gila trout is native to tributaries of the Gila River in Arizona and New Mexico. The Gila trout is found historically in the Verde and Agua Fria drainages in Arizona. A note in the archives of Aldo Leopold, dated 1923, contains anecdotal evidence of a native trout in Tonto Creek, AZ. Gila trout have persisted in five streams within the Gila National Forest, New Mexico, including: Iron, McKenna, and Spruce creeks in the Gila Wilderness Area, along with Main and South Diamond creeks in the Aldo Leopold Wilderness Area.

Description

Gila trout have a yellow body, with black spots. The average total length is about 30 cm (11.8 in); with maximum total length approximately 55 cm (21.7 in). Gila trout are closely related to Apache trout. However, Apache trout can have a spot behind and in front of the pupil (eye) and big noticeable spots on the body whereas Gila trout are characterized by numerous small dark spots on the upper half of the body.

Biology Gila trout can be found in small mountain water streams, and in confined pools. They are opportunistic feeders that feed on aquatic insects such as trichopterans, ephemeropterans, chironomids, and coleopterans, as well as small fishes.

Reproduction Depending on the water temperature, spawning season occurs in late spring and summer. The number of eggs produced from females held in hatcheries averaged about 150. The maximum fecundity observed was 686 eggs.

Conservation The Gila trout has been threatened by competition and hybridization with introduced game fish such as the rainbow trout. However, the primary cause of reduced Gila trout populations is habitat loss caused by loss of water flow and shade-giving trees, caused in turn by fires, human destruction of riparian vegetation, livestock overgrazing, agricultural irrigation and water diversion, and channelization of streams in the Gila trout's native range. By the time the Gila trout was listed by the U.S. Fish and Wildlife Service in 1967 its range had reduced from several hundred miles of stream to just 20 in the Gila Wilderness and Aldo Leopold Wilderness. After listing USFWS began an aggressive program of stream restoration, removing the introduced trout, restoring and repairing riparian vegetation (to maintain cooler water temperatures), and restocking restored streams with young Gila trout. The Mora National Fish Hatchery and Technology Center in northern New Mexico keeps brood stocks of the Gila trout and supplies the fish for restocking. The species is now more secure than it was in the 1970s, having been moved to 10 new streams, though populations and habitat are still far below those originally established. Conservationists hope to eventually delist the species and allow fishing, thus forming alliances with fishermen in order to help preserve the species. Major wildfires and drought will always play a major role in the status of any trout species.

References

"Oncorhynchus gilae". Integrated Taxonomic Information System. Retrieved 24 January 2006. Froese, Rainer; Pauly, Daniel (eds.). "Oncorhynchus gilae". FishBase. October 2005 version.

External links

YouTube video Catching A Gila Trout

Illustrations

Worked examples

Example 1 — a first encounter with Gila trout

Start with the simplest possible case. Write down what Gila trout claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Gila trout before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Gila trout ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Gila trout

In research: Gila trout appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Gila trout in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Gila trout is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cold water fish, ESA threatened species, Endangered fauna of the United States, so understanding it makes those chapters shorter.
In everyday life: Look for Gila trout outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Gila trout in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gila trout means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Gila trout out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gila trout in simple terms?

The Gila trout (Oncorhynchus gilae) is a species of salmonid, related to the rainbow trout, native to the southwestern United States. Prior to 2006 the Gila trout was federally listed as endangered.

Why does Gila trout matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Gila trout?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Gila trout.