Largemouth Bass

Largemouth Bass, Micropterus salmoides

The Largemouth Bass, Micropterus salmoides, whose common Spanish name is lobina negra, is a member of the Sunfish or Centrarchidae Family, known collectively as lobinas in Mexico. Globally, there are fourteen species in the genus Micropterus, two of which are found in the streams, rivers, lakes, and ponds of Mexico’s freshwater systems.

The Largemouth Bass have fusiform bodies that are somewhat laterally compressed and moderately deep with an oval cross section. They are green overall and transition to pale green and almost white ventrally. They have dark blotches on their sides and a prominent lateral stripe that runs from their snout through their eyes to the base of their caudal fin. Their eyes are golden brown. Their anal fin has 3 spines and 10 to 12 rays and their caudal fin is rounded; two separated dorsal fins, the first with 9 or 10 spines and the second with 10 to 13 rays. Their head has a large terminal slightly oblique mouth that reaches far beyond the rear margin of their eyes. They are covered with large scales.

The Largemouth Bass are found in clear quiet water but can survive in a variety of habitats; they are seldom found at depths of more than 20 feet. They grow rapidly and reach an average length of 46 cm (18 inches) and up to 15 pounds in weight. The world record, caught in a lake in Georgia in 1932, is 96.5 cm (38 inches) and 10.1 kg (22 pounds 4 ounces). A 15 cm (6 inch) Largemouth Bass is one year old, a 30 cm (12 inch) fish is two years old, and a 40 cm (16 inch) fish is three years old. They are tolerant of water temperatures up to 30oC (86oF) but become less active at elevated temperatures. They are normally found as solitary individuals. Adults are classic ambush predators and feed almost exclusively on other fish and large invertebrates such as crayfish; larger fish also prey upon smaller bass. Except for humans, they are the top predator in their aquatic ecosystem and rarely become prey due to their size, swimming speed, and protective dorsal fin spines. Reproduction is oviparous and occurs when water temperatures are in excess of 18oC (66oF). Males select the nest site in two to eight feet of quiet vegetated water over sand, gravel or pebbly substrate and clear out a small depression. Gravid females then approach the nest site and each deposits between 2,000 and 145,000 eggs. The eggs are fertilized externally and females leave shortly thereafter. Females are known to mate with several males. Males remain on the nest providing protection from predation from other fish and birds and from debris. The eggs hatch in five to ten days. The fry remain near the nest under the male’s watch for several days feeding primarily on zooplankton and insect larvae. Once they reach two inches, they become active predators. They have a lifespan of up to twenty-three years.

The Largemouth Bass are native to the Florida Everglades. Due to their importance as game fish, they have been introduced into many other areas making them perhaps the most widely distributed fish in the world. They are found in all types of freshwater systems including swamps, ponds, lakes, reservoirs, creeks, large rivers, and estuaries of northern Mexico and are most likely moving toward southern Mexico as we speak. They are the State Fish of both Alabama and Florida.

The Largemouth Bass is most often confused with the Spotted Bass, Micropterus punctulatus (fused spiny and soft dorsal fins), a resident of the southeast United States and the Smallmouth Bass, Micropterus dolomieu (mouth ending at middle of eye).

The Largemouth Bass are one of most sought after game fish in the world. One of the great recreational angling experiences I have had is fishing for Largemouth Bass with fly rod and a small popper in Lake Okeechobee and supporting canals of Southern Florida. They are also considered an excellent food fish. They are widely distributed and from a conservation perspective are currently considered to be of Least Concern. In several countries where they have been introduced they have quickly become highly invasive and a detriment to local environments. As with nearly all aquatic species, pollution and drought are the biggest threats to their existence and survival. They are highly prized for their food value.

Largemouth Bass (1)Largemouth Bass, Micropterus salmoides. Fish caught out of an irrigation pond in the greater Los Cabos area, Baja California Sur, on a fly rod, January 2008. Length: 35 cm (14 inches). Catch courtesy of Eduardo Correa, Mexico City, Mexico.