TN00220 LARGEMOUTH BASS MICROPTERUS SALMOIDES
PHYSICAL DESCRIPTION: This is a stripe sided, very large-mouthed bass with a deeply notched dorsal fin. This is the largest and most robust of the genus with the adults from 230-650 mm TL. The body is somewhat elongate, slightly compressed and stocky with a prominent belly in the large adults. The dorsal profile of the head is slightly to moderately convex and the mouth is terminal and large. The dorsal fin is deeply emarginate at the junction of the spinous and soft portions, the caudal fin is moderately forked and the pectoral fin is rounded. Teeth are lacking on the tounge. The genital pore is pear-shaped in the mature male and round in the female. There are 58)61-65(69) lateral line scales with 7-8(9) scales above the lateral line and (14)15-17 below the lateral line. There are (24(26-28(30) circumpeduncles scales, (9)10(11) dorsal spines, (11)12-13(14) dorsal rays, (2)3 anal spines, (10)11(12) anal rays and (13)14-15(17) pectoral rays. The midlateral stripe or blotches are olive to olive-black and the dorsum is olive with brassy and green sheens and a dark olive mottling. The lower side and venter are dirty opalescent white and the cheek bars are olive. The opercular spot is black. The dorsal and caudal fins are pale to medium olive with an olive-brown mottling. The anal and pelvic fins are off-white and the pectoral fin is pale orange-olive *4205*. The color varies according to the water: (1) in clear, sand bottom or gravel bottom of lakes and streams the color is green sides shading into wjite on the belly, (2) in mud or moss bottom lakes or sluggish streams the color is black on the back and sides with a gray or yellow belly, (3) the black stripe is always present along the sides from the gills to the tail with darker blotches along and above the lateral line *1151*. REPRODUCTION: Spawning typically begins in the spring when the water temperatures reach from 16-18 degrees C, although spawning has been recorded at temperatures up to 24 degrees C *4205*. The incubation time ranges from 2 to 7 days, depending on the water temperature. Florida subspecies nest and spawn earlier than northern subspecies at a 1-3 degree C lower temperature. Gravel substrate is preferred for spawning, but they will nest on a wide variety of other substrates, including vegetation, roots, sand, mud, and cobble. The nests are constructed by the male at water depths from 30-60 cm up to 8.2 meters *4205*. Nests have been found as deep as 8.23 m in a reservoir where the depth increased during the spawning period. Factors influencing reproduction and the survival of eggs are: (1) Water level fluctuation, (2) wind and wave action, (3) water quality, (4) aquatic and terrestrial cover, (5) air and water temperatures, (6) invertebrate and fish predation, and (7) human activity *1272*. Spawning activity occurs in the spring when water temperatures reach 15-24 degrees C *1272,1274*. In a constant temperature environment, spawning occurs in the spring and summer *1281*. The day length also affects spawning *1282*. Sexual maturity is related to size and age, and somewhat smaller, age II bass may be sexually mature and age III or age IV bass are almost always sexually mature *1152,1285*. The males prepare nests in shallow water along the shore on gravel or exposed bottom detritus. The nests require protection from wind and wave action, and are spaced 1-2 meters apart *1273,1283*. The nests are circular and twice the length of the fish in diameter, and are created with characteristic nest building behavior *1283*. The majority of spawning occurs near dusk or dawn *1283*. The nests contain 5,000-82,000 eggs *1273*. In Miane, adults age 4-6 average from 17,501-21,751 total ova. The fertilized eggs are yellow-orange, spherical and 1.4-1.8 mm in diameter *1279,1283*. There is an increase in the number of eggs in females with increasing size *1152*. Ovum production decreases in fish over 7 years of age *1279*. The egg hatch success is highest at a constant temperature between 55-75 degrees F and unincubated eggs can last up to 4 days prior to death. Egg mortality may result from the lack of aeration, an increase in silt and respiratory wastes *1279*. The eggs hatch in 2-5 days *1279*. The time of spawn depends on the condition of bass and the turbidity of the water, muddy water delays egg laying, and smaller bass spawn later than larger bass. The food supply in the fall and spring determine the amount of reproduction in the spring *1156*. BEHAVIOR: Courting behavior follows nest building behavior and both fish undergo vivid color changes, with the pair swimming over the nest with vents in close contact. The eggs and semen are emitted simultaneously for fertilization, and spawning ends when the female swims away and the male guards the nest *1152*. They exhibit crepuscular activity, and also a midday activity peak *1156*. They feed in shallow water *1156*, year round but slow down during the winter months *1180*. A low temperature (less than 10 degrees C) inhibits feeding *836*. Activity is depressed during dark periods *1156*. They are attracted to prey items by sight and vibrations on the lateral line from the water (low frequency sounds) *1152*. There is general use of the inshore zone in the summer, with offshore movement in the winter. They will migrate to warm water discharges of power plants in the winter *1152*. The temperature influences movement activities *1152*. This species homes to its area if displaced *2654,1314,2653,1178,1291*. The range is usually a single pool *2654,1314,2653,1178*, and home pools are established by 60-80% of adult fish *2653,339*. Low water levels in streams are a barrier to homing move- ments *2653. This species nests in water less than 30 inches deep along the margins of deep pools or shoreline *2653*. The adults are piscivorous summer and fall, while in the winter and spring they eat crustaceans, insects, and fish *2318*. 80-90% of their time is spent in non-movement activities such as holding and shelter use. Movement activities include feeding, agonistic behavior and position changing *2645*. A visual reference point is the first feature to attract bass to cover, and an increased area of darkness of cover increases the use of the cover. Darkness is the key factor in cover seeking. An area of quiet water is important for cover use *2646*. Distribution between bass species is influenced by stream gradient, water surface shade, substrate, and land use *2653*. There is an upstream migration of adults in the spring, and a downstream migration in the fall *2647*. Movements of fish are influenced by temperature, dissoved oxygen, food, and habitat *2649*. The normal rate of growth for an adult is approximately 454 grams/year. Largemouth bass mature and spawn as early as age I near the southern limit of their range. Maturity is delayed among more northern populations. Maturity is reached in 3-4 years for males and 4-5 years for females in Canada. The maximum known age of largemouth bass is 15 years. ORIGIN: This species is native to the Great Lakes, the St. Lawrence and Mississippi basins and the southern Atlantic and Gulf slopes. In Virginia, M. salmoides salmoides are probably native to the Tennessee and Big Sandy drainages while introduced to the New and Eastward *4205*. Limiting factors: Lacustrine environments are the preferred habitat. Lake areas that are less than 6 meters deep may not provide adequate overwintering habitat in northern latitudes. Bass are considered intolerant of suspended solids and sediment *JRK6*. Weather conditions strongly influence the survival of the young-of-year, especially during the first month *1287*. The strenth of the year class depends on the survival of the young during the first month *1152*. Rainfall patterns, water level, and temperature determine the abundance of the young *1284*. There are two critical stages in the early life history, due to temperature vulnerability: (1) egg fertility to hatch, (2) the first winter of the young-of-year *2648*. Large fish can withstand winter starvation better than smaller fish since the rate of basal metabolism will increase with the increase in fish size *2648*. POPULATION PARAMETERS: The elements to model a fish (bass) population in a reservoir are: (1) they need a minimum of 25 lbs/acre of predator (bass), (2) a minimum of 75 lbs./acre of plankton feeders (e.g. shad, and (3) a minimum of 100 lbs./acre bottom feeders (e.g. catfish). Production of these 3 factors is controlled by the fertility of the water, climate, water level fluctuations, the shape of the basin and substrate composition *1271*. Biological factors which influence early life stages are (1) the size of spawning population, (2) predation and cannibalism, (3) disease and fungi (important in hatcheries, not in the wild), and (4) starvation (important in hatcheries, not evident in wild populations) *1155*. Factors to estimate the standing crop of bass are: (1) water depth, areas of watershed, and areas underwater, (2) fertility of the water and watershed, (3) the species composition of the system, (4) population estimates, (5) the average seasonal water temperature, and (6) the length of the growing season *1292*. The growth of fry is retarded at low temperatures and accelerated at high temperatures, with maximum growth between 27.5-30.0 degrees C *1286*. Embryo survival averages 80%, and brood dispersal occurs in midsummer *1152*. The rates of fry and fingerling development, particularly in the first 4 weeks, relate directly to the mean daily water temperature *1273*. The number of young-of-year (fingerlings) in the fall is independent of the number of eggs or brood fish in the spring *1287*. The growth rate is highly variable, and ranges from 5-35 cm at the end of first year *1152*. Growth is slower in turbid water (due to the scarcity of plankton and forage fish), and the presence of competitor fish *1288*. There is no difference in growth rates between sexes *1152*. This species may live up to 15 years, although usually 6 years or less. Females tend to live longer than males *1180,1181*. Population densities of 50-100 adults/acre are 'strong' bass populations, and densities above 100/acre can cause stunted populations. Weak populations are characterized by a few, relatively large fish *1152*. In ponds and lakes, standing stocks range from 2-142 kg/hec., and were commonly from 45-67 kg/hec. (40-60 lbs/ac) *1180*. Fingerling mortality is attributed to the adult fish's cannibalism, whith their abundance influenced by alternate prey for adult fish *339*. Growth is inversely related to population density, and curvilinearly related to forage crop. They are food dependent at low food availability and independent at high food availability *2643*. Growth in the first year positively correlates with the lake level. AQUATIC/TERRESTRIAL ASSOCIATIONS: This species is associated with Lepomis macrochirus, L. megalotis, L. auritus, L. gibbosus, L. microlophus, Micropterus dolomieui, M. punctulatus, Ambloplites rupestris, Pomoxis annularis, and Notropis spp *842*. POPULATION PARAMETERS: IN TENNESSEE AND KENTUCKY WATERS, AVERAGE TOTAL LENGTHS AT SUCCESSIVE ANNULI WERE 153, 268, 352, 404, 446, 484, 539, AND 579 MM, RESPECTIVELY *1178*, WHEN BASS REACH LENGTHS OF 100- 200 MM, LARGE FORAGE SUCH AS FISH AND CRAYFISH MUST BE AVAILABLE FOR RAPID GROWTH TO OCCUR *2618, TN5373*
| Life History |
References for Life History Codes
JRK6, 1178, 1180, 1181, 835, 836, 1185, 1151, 1152, 1154, 1273, 1274, 1279, 1281, 1282, 1283, 1285, 1287, 1288, 1156, 1289, 1290, 1291, 1292, 2654, 1314, 2653, 339, 2318, 2645, 2646, 2647, 2648, 2649, 2643, 4205
Comments on Life History Codes