biology

Oncorhynchus masou

Oncorhynchus masou 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 Oncorhynchus masou rather than just read about it. In short: The masu salmon (Oncorhynchus masou), also known as masu (Japanese: マス, lit. 'trout') or cherry trout (桜鱒, サクラマス, sakura masu) in Japan, is a species of salmonid belonging to the genus Oncorhynchus, found in the North Pacific along Northeast/East Asian coasts from the Russian Far East (Primorsky, Kamchatka Peninsula, Sakhalin and Kuril Islands) to south through Korea, Japan and Taiwan. Although generally accepted as…

Key takeaways

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

Reference excerpt

The masu salmon (Oncorhynchus masou), also known as masu (Japanese: マス, lit. 'trout') or cherry trout (桜鱒, サクラマス, sakura masu) in Japan, is a species of salmonid belonging to the genus Oncorhynchus, found in the North Pacific along Northeast/East Asian coasts from the Russian Far East (Primorsky, Kamchatka Peninsula, Sakhalin and Kuril Islands) to south through Korea, Japan and Taiwan. Although generally accepted as a salmon in the West, the fish is actually regarded as a trout in Japan (its most famous native range) as it is the most commonly seen freshwater salmonid in the Japanese archipelago. A number of subspecies are known, including the widespread nominate subspecies yamame (O. m. masou), the critically endangered Formosan salmon (O. m. formosanus) in landlocked waters of Taiwan, the Biwa trout (O. m. rhodurus) endemic of Lake Biwa, and the anadromous amago (O. m. macrostomus) restricted to western Japan.

Appearance

A masu salmon which has reached sexual maturity has a darkened back, and the stripes on the body sides become bright red with crimson tinge to merge on the abdomen into one common longitudinal band of lighter color. For this reason, it was given the name cherry salmon. As adults, masu salmon tend to weigh 2.0 to 2.5 kg (4 lb 7 oz to 5 lb 8 oz) and measure roughly 50 cm (20 in) in length. The maximum size that can be attained by this species (which is in the region of Primorsky Krai) is 71 cm (28 in) long and 9 kg (19 lb 13 oz) in weight.

Ecology

On average, this salmon prefers a temperate climate around the latitude of 65–58°N, and in the sea, it prefers a depth of 0–200 m (0–660 ft).

Life cycle

Like other Pacific salmon, masu salmon's biological life cycle is subdivided into freshwater and marine periods; in rivers, this species lives from 1 to 3 years and can form living freshwater forms. The sea lifecycle, depending on the age of the young, continues for 2.0 to 3.5 years. In the sea, the masu salmon feeds intensely on crustaceans, less often on young fish. On attaining sexual maturity, in its third to seventh years of life, it enters rivers to spawn. Its spawning run starts earlier than that of other salmon species. After spawning, most passing fish die, and those that remain alive (preferentially dwarf males) participate in spawning the next year, too. Emerging from the nest, the young do not travel to the sea immediately, but remain in spawning areas, in the upper reaches of rivers, and on shallows with weak currents. The young move to pools and rolls of the river core to feed on chironomids, stone flies, and may fly larvae, and on airborne insects. The masu salmon travels to the ocean in its second, or occasionally even third year of life.

Economic importance

This salmon, like most others, is a highly commercial species caught in fisheries, raised for aquaculture, and sought after as a game fish. It is marketed fresh and frozen and is often eaten broiled or baked.

Subspecies and morphs

O. m. masou — Masu salmon, anadromous (sea-run) form; landlocked populations also called yamame (山女魚ヤマメ) O. m. ishikawae — Satsuki trout (皐月鱒サツキマス, satsuki masu), black-spotted form; landlocked populations also called amago (雨魚アマゴ) O. m. var. iwame — Iwame trout (岩女魚イワメ), recessive spotless form O. m. rhodurus — Type specimen is from Lake Ashi (Lake Hakone), previously identified as same species as Biwa trout (O. biwaensis) O. m. macrostomus — Red-spotted masu salmon; endemic to western Japan O. m. formosanus — Formosan salmon, Lishan trout (Chinese: 梨山鱒) or Slamaw trout (the Tayal name for Lishan), landlocked form endemic to mountainous central Taiwan

References

Illustrations

Worked examples

Example 1 — a first encounter with Oncorhynchus masou

Start with the simplest possible case. Write down what Oncorhynchus masou 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 Oncorhynchus masou 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 Oncorhynchus masou 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 Oncorhynchus masou

In research: Oncorhynchus masou 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 Oncorhynchus masou 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: Oncorhynchus masou is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fish described in 1856, Fish of the Pacific Ocean, IUCN Red List endangered species, so understanding it makes those chapters shorter.
In everyday life: Look for Oncorhynchus masou 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Oncorhynchus masou” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Oncorhynchus masou in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oncorhynchus masou 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 Oncorhynchus masou out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oncorhynchus masou in simple terms?

Why does Oncorhynchus masou 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 Oncorhynchus masou?

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 Oncorhynchus masou.