再次说明一下，原文转自英文版维基百科，自己凑合翻译的，附的那条虹鳟是前些天钓的， 老外的那条是刚头
Lifecycle
Like salmon, steelhead are anadromous: they return to their original hatching ground to spawn. Unlike salmon, which die after spawning, steelhead rejuvenate after spawning so they may return to the oceans to start the anadromous cycle once again. The steelhead smolts (immature or young fish) usually remain in the river for about a year before heading to sea, whereas salmon typically return to the seas as smolts. 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.
生命周期
就像大马哈鱼一样，刚头是溯河洄游的鱼类，它们返回最初的孵化地产卵。但和大马哈鱼不同的是，它们产卵后不会死去，刚头的身体可以重新幼化，使得他们能返回海洋再一次洄游。刚头转变成Smolt以后还会在河中停留一年左右，而大马哈鱼Smolt通常直接下海（注：Smolt是洄游鲑类幼鱼的一个特定时期的通称，这时鱼体发生适应海水生活的生理变化）。不同的刚头鱼群在不同的时间洄游。“夏季洄游刚头”5月至10月之间迁徙，在产卵前器官完全发育成熟。发育成熟过程在产卵前的春季淡水中完成。“冬季洄游刚头”溯河前在海中发育成熟，一般11月至4月间洄游，在返回以后短时间以内完成产卵。与大西洋鲑类类似，但不像他们的太平洋大马哈鱼近亲，刚头可以在幼态与性成熟态之间转换，在海水和淡水之间完成数次产卵旅程。
Diet
Rainbow trout have a varied diet. They are predators, eating any smaller fish from nearly the time they are born. Insects make up a large portion of the diet, along with crayfish and other crustaceans, some lake dwelling species may become planktonic feeders. Trout of all ages will eat nearly anything they can grab, in contrast with the legendary, selective image people often have of the animal s nutrition habits. They are near the top of the food chain in most freshwater environments. However, they are lower on the rung of other freshwater predators such as pike, muskie, lake trout, and chinook salmon. Rainbows will take fish up to and over 1/3 of their length. However they are not quite as piscivorous or aggressive as the brown trout or lake trout, which is actually a char. The rule of thumb is that rainbows consume more fish and fewer insects as they grow, but insects continue to be a part of the diet in most all populations.
食性
虹鳟有着各种各样的食谱。它们是捕猎者，从出生开始就吃任何体型小于它们的鱼类。昆虫是食谱中的另一大组成部分，还有小龙虾和其它甲壳类动物，有一些湖泊种群可以以浮游生物为生。各种年龄阶段的鳟鱼都会吃掉任何它们能抓住的东西，和人们印象中这种动物的富有传奇色彩、选择性的饮食习惯形成对照。在多数淡水环境中，它们都处于食物链的顶端。然而，它们也是其它一些淡水捕猎者的食物，如梭鱼、北美狗鱼、湖鳟，和大鳞大马哈鱼。虹鳟可以吃下超过自己体长1/3的鱼类。但它们并不像湖鳟或者褐鳟那样食鱼为生、富有攻击性。湖鳟和褐鳟实际上是Charr（无对应中文意义，一类鱼的通称）。经验法则是随着虹鳟的成长食谱中鱼类增多，昆虫减少，但昆虫一直所有种群的食物来源。
As food
Rainbow trout and steelhead are popular in Western cuisine and are both wild caught and 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 earthy flavor which many people find unappealing; many shoppers therefore make it a point to ascertain the source of the fish before buying. Buhl, Idaho, United States is the world s largest producer of farmed rainbow trout.[citation needed] Rainbow trout are raised in many countries throughout the world. Rainbow trout that are wild and have a diet of scuds (freshwater shrimp) and crawdads are the most appealing, with orange pink flesh.
Steelhead are farmed, primarily in British Columbia and in Chile. Steelhead meat is pink like that of salmon, and is more flavorful than the light-colored meat of rainbow trout..[3]
In some places if fished and cleaned immediately the meat isn t nutty or earthy, but a sweet and clean flavor. Especially if it is a native rainbow trout.
可食性
野生和养殖的虹鳟和刚头都是西方烹饪中常见的食材。它有着细嫩的肉和清淡带点坚果味道的风味。然而，养殖的和某些湖里捕捞的鳟鱼有着不招人喜欢的明显土腥味（很难准确翻译），所以很多顾客会在购买前重点确认鱼类的来源。美国爱达荷州的 Buhl 是世界上最大的虹鳟养殖地。虹鳟在世界上许多国家都有养殖，以河虾和小龙虾为食的野生虹鳟有着最为吸引人的橙粉色的肉。
刚头主要在英属哥伦比亚和智利有养殖。刚头的肉像大马哈鱼一样是粉红色的，比浅色的虹鳟肉更为可口的。
在某些地方如果捕获以后马上清理，鱼肉没有坚果味或土腥味，而是甜而清淡的风味。特别是野生的虹鳟（真怀疑原文是不是老中编的）。
Fisheries
Rainbow trout and steelhead are both highly desired sport fish. There are some tribal commercial fisheries for steelhead in the Puget Sound, the Washington Coast and in the Columbia River. Most rainbow trout and steelhead harvest in the United States is supported by hatchery production.
渔业
虹鳟和刚头都是广受欢迎的运动鱼种。在华盛顿州海岸的 Puget Sound港和哥伦比亚河有一些部落的（应该是印第安人的）商业渔场。美国多数的虹鳟和刚头捕捞有着孵卵场的放流支撑。
Threats and Conservation
Steelhead trout have declined due to a number of human and natural causes. The U.S. National Marine Fisheries Service has a detailed description of threats. Steelhead that spawn in Southern California streams (south of Point Conception) have been particularly decimated by habitat loss due to dams, confinement of streams in concrete channels, water pollution, groundwater pumping, Urban heat island effects, and other byproducts of urbanization. This sub-population is believed to have adapted to higher water temperatures and to natal streams not being suitable for spawning every year, depending on weather variability and other factors. It has been named "southern steelhead" and is the focus of major restoration efforts.
Most steelhead populations, technically called Distinct Population Segements, in Oregon, Washington, and California have been listed under the U.S. Endangered Species Act as either threatened or endangered species. This decision has been controversial, however, particularly among the community of anglers who fish for them, since the freshwater form is typically not considered to be endangered, while being technically the same species. However, steelhead face different mortality pressures not faced by resident rainbows. These mortality sources often involve their migration, ocean survival, and harvest.
资源威胁与保护
刚头因为一系列人为和自然的原因衰落。美国“国家海洋渔业服务处”有着详尽的威胁因素描述。在南加利福尼亚溪流中产卵的刚头大部份已经消失，主要原因是栖息地因为水坝、溪流被封入密封的水泥通道、水体污染、地下水汲取、热岛效应和其它城市化的负产品。这一亚种群被认为是已经适应了较高的水温和因为气候变化和其它因素引起的不是每年都适于产卵的溪流。它们已经被命名为“南方刚头”是种群保护恢复的重点对象。
俄勒冈、华盛顿、和加利福尼亚的多数刚头种群，专业名称为“地区亚种？”已经列入美国濒危物种目录，作为易危或者濒危物种。这项决定引起了争议，尤其是在垂钓的人群中，因为淡水生活的虹鳟从来没有濒危，但理论上说来它们又是同一物种 。然而刚头需要面对淡水生活虹鳟不必面对的死亡率压力，这些死亡率来自于洄游、海洋生存和捕捞。
终于干完了，内容稍有删节