Rainbow trout
The rainbow trout , aka redband trout, is a species of Pacific
salmon native to tributaries of the
Pacific Ocean in
Asia and
North America. Fish which have gone to sea are known as steelhead, or ocean trout . The species has been introduced for food or sport to at least 45 countries, and every continent except
Antarctica. In some of these locations, such as
Australia, they have had very serious negative impacts on upland native fish species.
The naming of the rainbow trout species was based on fish taken in
Oakland,
California, from what is now Redwood Creek, in the San Leandro Creek drainage.
Encyclopedia
The
rainbow trout , aka
redband trout, is a species of Pacific
salmon native to tributaries of the
Pacific Ocean in
Asia and
North America. Fish which have gone to sea are known as
steelhead, or
ocean trout . The species has been introduced for food or sport to at least 45 countries, and every continent except
Antarctica. In some of these locations, such as
Australia, they have had very serious negative impacts on upland native fish species.
The naming of the rainbow trout species was based on fish taken in
Oakland,
California, from what is now Redwood Creek, in the San Leandro Creek drainage. In 1855, Dr. W. P. Gibbons, founder of the
California Academy of Sciences, was given three specimens obtained from the creek. He described and assigned them the scientific name
Salmo iridia. It was later determined that Gibbons and Walbaum were referring to the same species, and the original binomial name is now used to refer to the species.
Physical characteristics
Rainbow trout are unusual in that although they can spend their entire life in fresh water, they are capable of migrating to sea water when conditions are right, though they must return to fresh water to breed.
The freshwater form is called "rainbow trout" or "redband trout", based on the broad red band along their sides. After going to sea, their color changes, including loss of the red band, and they are called "steelhead".
They occur in cool streams up to 4,500 m in elevation.
Rainbows and steelhead have small black spots along their back,
dorsal fin and
caudal fin. Rainbows have a red or pink streak that runs from the
gill cover to the caudal fin, inspiring their name. The color of a rainbow's back varies from blue or green to a yellow-green or brown. Steelhead usually lack the pink stripe and have chrome-colored sides. Rainbows are distinguished from their cousins, the cutthroat trout by their short maxilla, which reaches to, but not past the rear margin of the eye. Rainbow trout also lack hyoid teeth, a feature present in cutthroat trout.
Rainbows range from 30 to 45 cm in length. Steelheads grow longer, ranging from 50 to 100 cm in length. Steelhead range in weight from 2.5 kg to 10 kg.
Lifecycle
Like
salmon, steelhead are anadromous: they return to their original hatching ground to spawn. Different populations of steelheads migrate upriver at different times of the year. "Summer-run steelhead" migrate between May and October, before their reproductive organs are fully mature. They mature in freshwater before spawning in the spring. "Winter-run steelhead" mature fully in the ocean before migrating, between November and April, and spawn shortly after returning. Similar to Atlantic salmon, but unlike their Pacific
Oncorhynchus kin, steelhead are
iteroparous and may make several spawning trips between fresh and salt water.
As food
Rainbow trout is popular in Western cuisine and is often
farmed for food. It has tender flesh and a mild, somewhat nutty flavor. However, farmed trout and those taken from certain lakes have a pronounced muddy flavor which many people find unappealing; many shoppers therefore make it a point to ascertain the source of the fish before buying.
Subspecies
A few populations are recognized as subspecies:
- California golden trout, Oncorhynchus mykiss aguabonita .
- Columbia River redband trout, Oncorhynchus mykiss gairdnerii .
- Kern golden trout, Oncorhynchus mykiss gilberti .
- Coastal rainbow trout, Oncorhynchus mykiss irideus .
- Kamchatkan rainbow trout, Oncorhynchus mykiss mykiss .
- Baja California rainbow trout, Nelson's trout, or San Pedro Martir trout, Oncorhynchus mykiss nelsoni .
- Great Basin redband trout, Oncorhynchus mykiss newberrii
- Sacramento golden trout, Oncorhynchus mykiss stonei .
- Little Kern golden trout, Oncorhynchus mykiss whitei .
References
External links
