Identification and Reproduction

Identification: 

• The largemouth bass is a carnivorous freshwater fish. 
• This fish is olive-green to green-grey, marked with a series of dark and even black blotches that form a horizontal stripe across the body. 
• As noted by its name, this fish is the largest out of all the black basses, it can reach a length of 40 cm. 

• Two dorsal fins are fused together. 
• Has a long, wide lower jaw that is slightly longer than the upper jaw. 

Reproduction: 

• Populations increase rapidly, as females lay up to 45,000 of eggs at a time and can spawn multiple times in a season. The number of eggs laid is impacted by her size. 
• Spawning occurs in late winter between January and February in the southern parts of US but will occur between May and June in northern regions. 
• These fish can reach sexual maturity as early as 3 months. 

Habitat & Ecology

• The largemouth bass lives in all water types, swamps, ponds, lakes, reservoirs, creeks and even large rivers. 
• Young largemouth bass primarily feed on small bait fish, scuds, small shrimp and insects. 
• Adult largemouth bass will feed on smaller fish, shad, snails, crawfish, amphibians, bats and even small water birds. 
• Prefers warm, shallow waters and are often found near stumps and aquatic vegetation, especially waterlillies, cattails, and other pondweeds. 
• These fish will grow much more slowly in weedy and vegetated waters, as this makes catching prey more difficult. 

Impacts

• In waters with little to no vegetation cover, largemouth bass can devastate the prey population. 
• As an introduced species it can permanately alter the native food web by eliminating native species. 
• Have been known to cause local extinction of native fish and amphibian species. 
• This fish is also capable of carrying hundreds of parasites that can spread to native species. 

Management

• Report this species if you think you have seen it; take photos, note exact location, date and any identifying features. 
• Always clean, drain and dry your boat and water equipment before leaving a waterbody. 

Resources

Download BC's Invasive Species Alert for Largemouth Bass here. 

For more information please refer to the Animal Diversity Web datapage on Micropterus salmoides: American black bass here. 

For more details check out the Invasive Species Compendium datasheet on Micropterus salmoides (largemouth bass). 

Header photo (Yinan Chen).