The Brown Trout, or Salmo trutta, is a freshwater fish with a brown or olive body and dark brown or red spots. They can grow as large as 10 lbs. and 102 inches. Trout that live in lakes are known as Lake Run Brown Trout and tend to be larger than their counterparts and are often silver in color with dark (if visible) spots. They have a square tail that features few, if any spots. The unique tail, or caudal fin, is one of their distinguishing features. Brown trout are native to Europe, Africa, and Asia and were first introduced to the United States in the 1880’s. They now occupy 44 states.
Brown trout typically spawn between October to December. The fish will swim up to headwaters to spawn if possible. If they cannot, due to barriers, they will spawn in the main river. The female will select a spot for the nest and dig up the gravel. The male will then follow her to the nest site where they will spawn, and then the female will cover the nest back up with the gravel. They will spawn at multiple nest sites until all her eggs have been deposited.
Brown trout can be opportunistic feeders or have a specialty that they prefer to consume. This will vary depending on their genetics and habitat. Smaller brown trout generally feed on insects and invertebrates while larger brown trout will eat fish, crayfish, amphibians, and small rodents as well as insects.
The brown trout is unique among trout species in that it is more tolerant of higher temperatures in the water. Their optimal temperature range is 50-66 degrees Fahrenheit, but they can survive in water up to 80 degrees. They will gravitate to rivers and streams with enough gravel to use for spawning but will have issues in water with too much fine sediment. They prefer clear water. In rivers and streams, brown trout will generally be found in pools of 3-6ft deep at a minimum. According to the US forest service, cover is more important to brown trout than other trout species. Rivers and streams with woody debris, boulders, and undercut banks all make excellent cover for the fish.
I think many people are surprised when they learn the brown trout is not a species native to North America. They have become so synonymous with our sporting and fly fishing culture that it seems like they have been here all along. You can find brown trout in almost every county in Michigan. See the Michigan fishing digest 2020 for specific rules and regulations.