Species

Largemouth Bass

Micropterus nigricans, (Cuvier, 1828)

freshwater

About Largemouth Bass

The largemouth bass (Micropterus nigricans) is a carnivorous, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern and central United States, southeastern Canada and northern Mexico. It is known by a variety of regional names, such as the widemouth bass, bigmouth bass, black bass, largie, potter's fish, Florida bass or Florida largemouth, green bass, bucketmouth bass, green trout, growler, Gilsdorf bass, Oswego bass, southern largemouth, northern largemouth, Alabama bass or Alabama largemouth, marsh bass, and swamp bass.

The largemouth bass, as it is known today, was first described by French naturalist Georges Cuvier in 1828. A 2022 study concluded that the correct scientific name for the Florida bass is Micropterus salmoides, while the largemouth bass is Micropterus nigricans. It is the largest species of the black bass, with a maximum recorded length of 29.5 inches (75 cm) and an unofficial weight of 25 pounds 1 ounce (11.4 kg). Reports from Cuba speculate bass as large as 13.5 kg (30 lb), where invasive largemouth thrive.

The largemouth bass is the state fish of Georgia and Mississippi, and the state freshwater fish of Florida and Alabama. It is a highly prized sport fish among anglers for their vigorous resistance when caught, and have been introduced to many regions due to their popularity in bass fishing and tolerance to urban streams. However, they have become an invasive species in some areas, causing the decline, displacement or extinction of native species through predation and competition.

Appearance

The largemouth bass is an olive green to greenish-gray fish, marked by a series of dark, sometimes black, blotches forming a jagged horizontal stripe along each flank. The upper jaw (maxilla) of a largemouth bass extends beyond the rear margin of the orbit.

The largemouth bass is the largest of the black basses, reaching a maximum recorded overall length of 29.5 in (75 cm) and a maximum unofficial weight of 25 lb 1 oz (11.4 kg). Sexual dimorphism is found, with the female larger than the male.

Largemouth bass prefer habitats with abundant littoral vegetation and generally maintain relatively small home ranges in lakes. They have an average lifespan of 10 to 16 years in the wild.

Diet

Juvenile largemouth bass consumes mostly small bait fish, scuds, water fleas, copepods, small shrimp, and insects. Adults consume smaller fish (bluegill, banded killifish, minnows, juvenile bass), shad, worms, snails, crawfish, frogs, snakes, and salamanders. In larger lakes and reservoirs, adult bass occupy slightly deeper water than younger fish, and shift to a diet consisting almost entirely of smaller fish like shad, yellow perch, ciscoes, suckers, shiners, other cyprinids, freshwater silversides, and sunfish (such as bluegill and green sunfish). It also consumes younger members of larger fish species, such as catfish, trout, walleye, carp, white bass, striped bass, and even smaller black bass. Among the crayfish species preyed upon include Faxonius difficilis, F. harrisonii, F. hartfieldi, and Procambarus clarkii.

Humans & conservation

To better understand the effects of angling on largemouth bass populations, researchers have studied physiological variation in the largemouth bass. One study found that in areas where angling was high, there was a significant effect on bass physiology. In stress tests, bass from protected areas had increased cortisol responsiveness compared to those in the highly active fisheries. The largemouth bass in Freshwater Protected Areas also had a higher aerobic scope, potentially providing them with more energy for growth, reproduction, and responding to environmental change. Another study found that maternal exposure to the stress hormone cortisol resulted in a lower responsiveness to angling stressors in their progeny.