During the last 130 years numerous nonnative fish, invertebrate, and plant species have been introduced intentionally and unintentionally to Lake Tahoe altering aspects of its ecology. The first series of intentional fish introductions occurred between the end of the 19th century and the 1940’s. From that initial introduction, rainbow trout, brown trout, lake trout, and brook trout and kokanee salmon still persist today. Other species, such as the crayfish and Mysid shrimp were introduced purposely by resource managers to provide additional food sources for game fish.

More recent introductions of the popular sport fish largemouth bass and bluegill were illegal and not intentional. Some plant species (Eurasian watermilfoil and Curly leaf pondweed) were initially established in the Tahoe Keys lagoon and have continued to spread to other locations around the lake. The Asian clam was initially identified in 2002 and today large, high density (~1500 clams per square meter) beds exist in the southeast portion of the lake.

Whether intentional, accidental or illegal, these species introductions can have profound impacts on Lake Tahoe's native ecosystems and water quality. Working in collaboration with other universities, state and federal resource agencies, TERC continues its history of understanding population dynamics and ecology of introduced species. During the past decade, TERC has also been involved with the Basin’s resource management agencies developing control strategies for these species.