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Thursday, May 16, 2019

Species of the Month

Wherever you live, fishing season is in full swing. This month we'll profile one of the most common game fishes, the rainbow trout. They can be found in lakes and streams almost everywhere around the world, though introduced to many of them.
Rainbow trout (State Department)
Scientific name: Oncorhynchus mykiss
Kingdom: Animalia (animals)
Class: Actinopterygii (ray-finned fishes)
Order: Salmoniformes 
Range: Pacific coast of North America from Alaska to Mexico
Habitat: Aquatic, some also have a marine phase
Lifespan: 6-8 years average, up to 11 years
Diet: Insects, insect larvae, crustaceans, small fish, algae
Predators: Lampreys, eagles, osprey, herons, mergansers, bears, mink, river otters, seals, sea lions, other fish, humans
Fish on! (NPS)
Conservation Status: No special protection for freshwater only fish; nine populations of steelhead are listed as threatened or endangered
Steelhead (NOAA Fisheries)

Other information: Rainbow trout get their name from a colorful iridescent streak along the sides of its body. State fish and game agencies around the country raise them to stock streams and lakes for fishing season. Stocked trout remain in freshwater; some native trout along the west coast are anadromous (have a saltwater phase) and return to their birthplace to spawn and die. The anadromous trout are called steelhead. Females lay eggs in a gravel nest called a redd. Fertilized eggs hatch after a few weeks, and the hatchling remains attached to the yolk sack as a food source before leaving the redd for the wider world. Young trout tend to stick to slower, shallow water. Young steelhead remain in the stream for up to three years before heading out to sea. Due to habitat degradation and loss, several western steelhead species are listed as threatened or endangered under the Endangered Species Act. Meanwhile, introduced trout are becoming a problem in some areas. They eat and/or outcompete native fishes such as cutthroat and brook trout. They threaten genetic integrity by hybridizing with native species. They also carry a parasite responsible for whirling disease, which causes deformities that make a fish easier prey.
Steelhead (NOAA Fisheries)

This week's information comes from University of Michigan's Animal Diversity Web and the US State Department, of all places.

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