Bull trout
| Bull trout | ||||||||||||
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Bull trout ( Salvelinus confluentus ) |
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| Scientific name | ||||||||||||
| Salvelinus confluentus | ||||||||||||
| ( Suckley , 1859) |
The bull trout ( Salvelinus confluentus ) is a species of char from the salmon fish family . It occurs in cold mountain waters west of the continental divide in the United States and Canada from Alaska to California. The bull trout is listed as an endangered species under the US Endangered Species Act .
features
The bull trout is usually just over 60 cm long. The animals living in rivers reach an average weight of 4 kg, those living in lakes weigh an average of 9 kg. The maximum length determined so far is 103 cm, the maximum weight 14.5 kg. In its external appearance, it is similar to the Pacific salmon ( Oncorhynchus ), but differs from them in the absence of palatal teeth and light (reddish, orange or yellowish) spots on a dark, olive or blue-gray basic color with a slightly silvery sheen. Oncorhynchus species are generally lighter in color and mottled dark. The bull trout's front fin rays are white. At spawning time, the males develop a reddish to orange belly.
Occurrence and habitat
The bull trout is native to northwestern North America. The southern limit of the distribution area is on the McCloud River in northern California, the northern limit in the extreme south of the Yukon Territory and in the east it occurs to the headwaters of some tributaries of the Columbia River in northern Nevada and Montana . In Alberta and British Columbia there are also some deposits east of the Continental Divide. The bull trout occurs in cold, clear, large and medium rivers and in large lakes and prefers water temperatures below 10 ° C. It mainly resides near the bottom of the water. In addition to the stationary inland form, there are also migratory populations that occur on the coast together with the dolly-varden trout ( Salvelinus malma ). The anadromous bull trout live in the sea for three years and when they reach sexual maturity, between four and ten years of age, swim upstream to spawn in their waters of birth. The fish spawn from August to October when the water temperature is less than 10 ° C. A female can lay 5,000 to 12,000 eggs, depending on size.
food
Young bull trout feed mainly on insect larvae, especially mayfly larvae and those of various two-winged species . As it grows up, the diet changes from predominantly insectivorous to piscivorous . Fish is a larger part of the diet of adult bull trout than most other salmonids. Important prey fish are the coregonine species Prosopium williamsoni , but bullheads , bottom perches , smaller salmonids and salmon spawn are also eaten.
source
- Timothy O'Brien, 2003. Salvelinus confluentus , Animal Diversity Web. Accessed February 22, 2016
Individual evidence
- ↑ Bull trout in the fish lexicon of freshwater fish
- ↑ Bull trout on Fishbase.org (English)
- ^ O'Brien (2003), section Physical Description
- ^ O'Brien (2003), Geographic Range section
- ^ O'Brien (2003), Habitat section
- ^ O'Brien (2003), Reproduction section
- ^ O'Brien (2003), Food Habits section
Web links
- Bull trout on Fishbase.org (English)
- Salvelinus confluentus onthe IUCN Red List of Threatened Species .
- Bull trout in the fish lexicon of freshwater fish