The family Salmonidae includes the numerous species of salmon, trout, whitefish and graylings. Fish species in this classification are valuable as food fish, and are prized as game fish. Species of salmonids live in both freshwater and saltwater in colder areas of the northern hemisphere. Salmonids are a widespread family of fish, although human use of waterways and overfishing threaten the numbers of some species in the wild.
Habitat
Salmonids live in both saltwater and freshwater. They feed on small crustaceans, small fish and a variety of insects. Their natural habitat is open waterways. Due to stocking programs and efforts to distribute the fish for anglers or for fish farming, they also live in man-made lakes. Fish farms may utilize closed freshwater lakes or ponds, especially for trout, or coastal tanks for raising salmon to market size.
The Pacific States Marine Fisheries Commission explains that fish are affected by the amount of sediment in the water, the oxygen level, the temperature, the flow of the water and by everything that happens in every stream and tributary in the entire watershed of a river system. Human intervention at one location can affect the watershed, and the habitat of fish, for hundreds of miles.
Migration
Adult salmonids migrate annually from lakes, rivers and ocean areas to the specific place in the stream where they hatched. Each generation follows the same migratory pattern. The Minnesota Department of Natural Resources uses an example of native salmon and steelhead trout that locate their home streams by using different innate homing mechanisms. They have microscopic iron particles in their brains that act as a directional guide similar to the magnetic orientation of a compass. They have a keen sense of smell, and they remember the specific smell of their home stream. Water chemistry is the source of the identifying scent, with the distinctive, memorable smell created by the runoff from surrounding woods and fields. Man-made lakes, dams, other obstructions and pollution in natural waterways can easily disrupt the natural migratory habits of salmonids.
Spawning
Spawning, or egg laying, is the reason for the annual migration of these fish. Not all species live in bodies of water that allow easy migration, and fish that have been transported from hatching areas to lakes are unable to find their home stream. According to salmonfishingguides.com, salmonids prefer clear, shallow water with pebble or gravel bottom for spawning. The shallow area is usually near a fast-moving current, which helps the fry on their downstream trek after hatching. Saltwater species move into freshwater streams and estuaries to spawn.
Conservation
Threatened species lists include some Salmonidae. The U.S. Fish and Wildlife Service works with various state and tribal agencies to restore these animals to their native waterways. One such program in eastern Oregon and southern Washington is successfully restoring bull trout to the Columbia River basin. Besides using radio tracking and surveys to monitor the population of these fish, detailed information and education materials are distributed throughout the area to help anglers identify the threatened species and avoid capturing them. Biologists work with other threatened species in a similar manner to ensure that these food fish populations will become sustainable.
Fishing and Fish Farming
Fish in the Salmonidae family are a rich source of high quality protein and healthy omega 3s for human consumption, making them valuable fish for marketing. According to pottsmerc.com, over-fishing has reduced the populations of wild salmon. Ecologists disagree on the best way to meet consumer demand for salmon during the years it will take for wild salmon to repopulate. Some experts believe that farm-raising the fish in coastal tank containers is the way to supply food needs. However, farm-raised salmon meat has inferior protein and nutrient values. The fish receive antibiotics and drugs to control diseases due to captive growing conditions, they are fed unnatural grain-supplemented feed, and their meat on this diet is grayish, so the feed contains dye to make their meat pink.
References
- Salmon Fishing Guides: A Little Bit About Salmon
- Pacific States Marine Fisheries Commission: Salmon Habitat: It's All Downhill
- Minnesota Department of Natural Resources: Who's That Navigator?
- Fish and Wildlife Service: Bull Trout: A Native Coldwater Fish
- "The Mercury," Montgomery County Community College: What is the difference between farmed and wild salmon
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