Iowa DNR
River & Stream Biological Monitoring
Fish and Benthic Macroinvertebrate Surveys
Physical Habitat Assessments

Brown Trout Salmo trutta

Salmonidae (Trouts and Salmons)
Trophic Class
Top Carnivore
Is Exotic to Iowa?
Is Lithophilous Spawner?
Is Hybrid?
State Listing Status
Not Listed
Assessment Program Statistics

This species was found at 83 bioassessment sites, 5 rapid fish bioassessment sites, 139 fisheries assessment sites, and 3 fisheries presence-only assessment sites. In total, it was collected at 211 distinct sites, or 14.3% of the 1473 total sites monitored by the bioassessment program. It is the 34th most commonly collected species.

The Brown Trout was collected in 190 bioassessment sampling sessions and 343 fisheries assessment sessions. It was present in 5 rapid bioassessment sessions and 3 presence-only sessions.

The biological assessment program has collected a total of 51,448 individual Brown Trout specimens, ranking it the #12 most collected fish.

Species Characteristics

As its name implies, this trout is generally brown, shading into a background of green and yellow. Spots on the sides are larger and more prominent than on other trout, and they are often bordered with a light-colored "halo". Few, if any, dark spots are found on the tail fin. The leading edge of all belly fins on Brown Trout is yellow or about the same color as the body. Lower portions of young Brown Trout are yellow, fading to gray or white underneath. Males, during the breeding season, often have vivid yellow to reddish-yellow colors along the belly and a sharply hooked lower jaw. The vomer, a bony structure in the roof of the mouth, has sharp teeth in an alternating "zig-zag" row. There are 115 to 150 scales in the lateral line.

Species Distribution Maps

HUC12 watersheds where this species has been found