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Largemouth Bass Biology and Life History

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Largemouth Bass Biology and Life History SRAC Publication No. 200 August 1997 VI PR Revision Largemouth Bass Biology and Life History James T. Davis and Joe T. Lock* The largemouth bass (Micropterus Largemouth bass will eat a variety salmoides) is one of several “bass- of live fish, but bluegill are partic- es” that are actually members of ularly important in ponds and the sunfish family. There are two small lakes because they repro- recognized subspecies, the duce throughout the warm Florida and the Northern, which months. This furnishes a continual will blend genetically. Although supply of different size forage. the two subspecies differ slightly Tilapia* and/or goldfish are com- in body structure, behavior, and monly used as forage on fish growth, biochemical tests are nec- farms and in intensively managed essary to positively identify them. Largemouth bass. lakes because more can be pro- duced at lower cost. About 5 Food and growth reflex action toward anything that pounds of live forage are required moves. (The bass motto: If food is for annual maintenance, and 10 Largemouth bass are valued by there, eat it.) pounds of forage are required to fishermen chiefly because of their add 1 pound of gain to large- The availability of adequate size fighting ability. They are vora- mouth bass. cious predators that readily strike live food (baitfish or forage) usu- artificial baits. Bass begin to eat ally limits bass growth. With ade- The swimming speed of large- fish when they are about 2 inches quate forage, largemouth bass can mouth bass has not been studied long. They swallow live fish and surpass 2 pounds the first year, in depth. For practical purposes, 1 other aquatic life whole rather but normal growth is about /2 expect bass to swim at speeds up than biting off chunks, which lim- pound. Mature females grow larg- to 2.5 times their body length per its the size of what they can eat. er than males, with Northern second. This means that small fish Depth of the body of the prey strains growing up to 10 pounds; swim about 2 miles per hour must be less than the mouth the males seldom exceed 5 while a 20-inch fish may swim in width of the bass. As a general pounds. Females of the Florida spurts of up to 12 miles per hour. rule the larger the bass, the larger strains and first generation crosses Largemouth bass do not grow the prey that will be selected. Very with Northern strains (F1) have well in muddy ponds because large bass usually will not prey grown to more than 20 pounds. they usually feed by sight. Water heavily on small fish. Their feed- These large sizes are directly clarity should be at least 15 inches ing habits are difficult to catego- affected by the forage available. and preferably 24 inches for feed- rize completely. One of the rea- Though farm ponds were the ing and best growth. Bass may sons that bass feed is to satisfy areas where record-sized bass also feed by attraction to sound or hunger. The other is apparently a were caught for many years, large vibrations in the water. This is reservoirs have yielded the most trophy-sized fish for the past 20 years. *Tilapia are illegal for use as forage in *Texas Agricultural Extension Service. some states. probably the best explanation for will be the area of choice. Males on water temperature. The male fishing success at night, but even normally guard the area about 6 will continue to guard the fry at night sight may be involved as feet around the nest. If there is an until they disperse, which may be bright moonlit nights are general- obstruction, males will often nest a period of 2 weeks or more ly preferred to very dark nights. closer together than 12 feet be- depending on temperatures. In There have been few studies on cause they are unable to see one nature, most nests are lost to sun- taste by largemouth bass. It is another. fish predation. often reported that bass will take After the nest is completed the Nesting success is also reduced if a bait and then “spit it out.” This male is often observed swimming the temperature drops below 60o may be a reaction to taste recep- in the vicinity of the nest search- F. This temperature usually caus- tion but may also be a reaction to ing for a compliant (ripe) female. es the male to leave the nest. the texture of the bait. When a ripe female joins the male, Without parental care the eggs The age of largemouth bass has they slowly circle the nest, side by will not hatch and predation will been reported to be up to 15 years side. Spawning occurs with both be increased. The fry feed on the in northern United States but is fish tilted laterally so their vents yolk sac of the egg for the first usually less than 11 years in the are close together. Both fish shud- few days. At 68o F they will South. It has also been reported der as eggs and sperm are develop mouthparts in about 190 that female bass live longer than released simultaneously. The male hours. Fry swim up when they are males. may turn and check on each about 8 days old and begin feed- Bass normally eat only live food release of eggs before resuming ing on zooplankton (cladocerans, but fingerlings can be trained to the spawning position. rotifers, copepods). They remain eat prepared rations under certain Spawning with multiple females in a school, guarded by the male, circumstances. See SRAC Publica- is common. Females normally for 2 to 7 more days before dis- tion No. 201, Culture of Largemouth release about one-half of their persing. They continue to feed on Bass Fingerlings, for more infor- eggs during the first spawn and zooplankton and add insect larvae mation. half of the remaining during the and fish to their diet when about second spawn. A third spawn up 2 inches long. Spawning to 1 month later is common. Normally fry feed about every Females average about 4,000 eggs three hours as this is the length of Largemouth bass in the South per pound of body weight, but the time necessary for food to pass will usually spawn when 1 year number can be quite variable. through the gut. Adult bass are old, if they are at least 10 inches Reports of up to 80,000 eggs from often observed to feed after about long. Males select a nest site in one female have been reported 14 to 24 hours depending on the the spring after the water temper- but the average is much smaller. size of prey devoured. ature has stabilized above 60o F. Larger fish tend to have larger Studies have found that large- Bass normally spawn at tempera- eggs and therefore larger fry but o mouth bass tend to move toward tures of 65 to 75 F in water fewer eggs per pound of body depths of 1 to 4 feet near shore, warm water in the colder months, weight. Usually at spawning the although this may be affected by but nesting has been observed as weight of eggs in females will be deep as 20 feet in clear water. prey availability. In addition, most 10 percent or more of her body bass will move less frequently There are some data, based on weight. During the spawning sea- induced spawning trials, that when water temperatures are son the male does not eat and below 50 or above 80o F. Large- indicate spawning is also affected many males die each year due to by photoperiod or day length. mouth bass apparently do not their poor body condition prior to learn quickly. There are some The male constructs a shallow, the spawning period. circular nest, about twice the bass in every population that are male’s body length in diameter, Males attempt to guard the nest non-learners. This may make up by sweeping away debris. Hard and fan the silt away from the the majority of the harvestable substrates such as sand or gravel eggs until they hatch. If he is suc- surplus. are preferred and if cover or any cessful, eggs hatch in 2 to 4 days form of structure is available, this in the southern U.S., depending The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 94-38500-0045 from the United States Department of Agriculture, Cooperative States Research, Education, and Extension Service..
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