Aquatic Invasive Species

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Warm-Water Fishes

Over the past decade Lake Tahoe has experienced a variety of plant and animal invasions, some of which are extremely detrimental to the food web within the lake. We are currently experiencing a warm-water fish invasion. These warm species include largemouth bass, smallmouth bass, crappie, bluegill and even goldfish. Distributional information suggest that most of these fish were introduced in the vicinity of the Tahoe Keys. It is very important and a public responsibility to help maintain the natural heritage of Lake Tahoe. Observed declines in Lahontan redside shiner and Lahontan tui chub have occurred as warm-water fish are known to be predatory and now occupy these native fish species preferred habitats along the south shore. We need your help to prevent any further introduction of non-native species (plants, fish, frogs, snails, mussels etc...) to this beautiful and unique ecosystem we call Lake Tahoe.

Largemouth Bass
(Micropterus salmoides)

As the name suggests, the Largemouth Bass has a gape large enough to devour fish up to half its size. They sometimes grow to a length of 16 inches, as a rule weigh under 10 pounds and live about 13 years. Spawning occurs in early May to June. They generally inhabit water less than 20 feet deep and seek the protection of aquatic and shoreline vegetation or rocky areas. Diet includes plankton, aquatic insects, crayfish and other fish.

Black Crappie
(Pomoxis nigromaculatus)

Black Crappie grow to a length of 7 - 10 inches, weigh 1 to 1 1/2 pounds and typically live 8 to 10 years. They usually spawn in March, April, May or late June. Habitat requirements include large streams and medium-size lakes and a preference for clear waters. In spring they inhabit heavily vegetated shallow waters and move to deeper water in summer. Their diet consists of zooplankton, insects, larvae, small fish and minnows.

Bluegill
(Lepomis macrochirus)

Nothing says warm-water fish invasion like a good old-fashioned Bluegill. Bluegill grow to an average of 6 to 8 inches long and have a life-span of 5 to 6 years. Spawning occurs in late spring or early summer. They favor warm water with plenty of cover such as aquatic weeds and submerged logs. Bluegill eat algae, zooplankton, insects and small fish.

Brown Bullhead Catfish
(Ictalurus nebulosus)

The Brown Bullhead Catfish grows to a length of 8 to 14 inches with an average weight of 1 to 2 pounds and has an average life span of 6 to 8 years. Spawning generally takes place in late April or May. As a rule they feed on or near the bottom at night and are omnivorous feeding on mollusks, insects, leeches, crustaceans, worms, plants algae, fish and fish eggs.

Goldfish
(Carassius auratus)

Please do not dump your goldfish into Lake Tahoe! Native to Asia, goldfish have been introduced worldwide due to their popularity as pond and aquarium fish. Releases, both intentional and unintentional, have meant that this species has formed wild populations in many locations. Goldfish impacts  on the aquatic community include increasing turbidity, predation upon native fish, and helping to facilitate algal blooms. Goldfish are among the most destructive non-indigenous species in North America, primarily because of their diet of aquatic vegetation. They strip waters of oxygen-producing plants which increases water temperatures and destroys habitat for native juvenile fish. In addition, the feeding habits of goldfish stir up sediments, which leads to a decrease in water clarity and inhibits plant growth. If goldfish populations get large enough we will see a further decline in the shorezone clarity of Lake Tahoe.

Related Links

100th Meridian Initiative
California Department of Fish and Game
Protect Your Waters
Tahoe Resource Conservation District - Aquatic Invasives
USGS - Exotic Fish

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