Richard L. Noble

Management of Forage Fishes in Impoundments of the Southern United States

Abstract Forage-fish management in southern ponds began in the early 1940s, and in reservoirs in the 1950s. Need for management arises from situations of both too many and too few prey for existing predators. The principal forage fishes stocked have been shads and silversides in reservoirs, sunfishes in ponds. Recent advances have been made in predator-prey assessment methodologies, with respect to both the need for and the effects of management, but these techniques have not yet been applied widely. Management of forage fishes has included direct control of forage populations with toxicants, drawdown of water levels to increase forage availability, supplemental stocking and diversification of predators, and predator harvest regulations. Forage-fish management has progressed from forage control to forage utilization and predator management, which makes efficient use of excess forage. Forage and predator species have been introduced with little evaluation of ecological relationships. Additional research mu...

Piscivory in Largemouth Bass as a Function of Aquatic Vegetation Abundance

Abstract The incidence of predation by largemouth bass Micropterus salmoides on fish in Lake Conroe, Texas, was examined over 7 years at two disparate levels of habitat complexity. When areal coverage of submersed vegetation ranged from 39 to 44% of the reservoirs 8,100 hectares, largemouth bass 100 mm and smaller in total length consumed fish infrequently; most did not consume fish until they reached lengths of 140 mm and more, Following the elimination of all submersed vegetation by grass carp Ctenopharyngodon idella, fish were consumed by most largemouth bass 60 mm or longer. The initiation of piscivory at smaller sizes resulted in significantly faster first-year growth for all largemouth bass year-classes produced after vegetation removal. Although shifts in the structure of the forage fish community occurred, ample fish prey existed for largemouth bass before and after vegetation removal. The onset of piscivory remained similar for largemouth bass collected along the dam riprap, where vegetation was...

Response of a Reservoir Fish Community to Aquatic Vegetation Removal

Abstract Over 3,600 hectares of submersed aquatic vegetation in Lake Conroe, Texas, were eliminated 1 year after 270,000 grass carp Ctenopharyngodon idella were stocked in 1981–1982. Seventeen fish species were commonly collected in cove rotenone samples and the biomasses of eight species declined (P ≤ 0.10) after vegetation removal. The most notable declines were observed for several small, phytophilic Lepomis spp., for bluegill Lepomis macrochirus, and for crappie Pomoxis spp. Biomass of largemouth bass Micropterus salmoides did not decline (P = 0. 12) but the density of age-1 and older fish did decline (P = 0.02). Biomass and density of two cyprinid species and channel catfish Ictalurus punctatus increased. Although biomass of longear sunfish Lepomis megalotis did not increase (P = 0.11), mean size declined and density increased an order of magnitude (P = 0.02). Density of threadfin shad Dorosoma petenense increased nearly fivefold after vegetation removal, coincident with a decline in mean size; howev...

Hatching Date Influence on Age-Specific Diet and Growth of Age-0 Largemouth Bass

Abstract Largemouth bass can hatch over a 70-d period, and among fish less than 90 d old, those hatched earlier can grow faster than those hatched later. Because faster growth of age-0 largemouth bass has been positively linked with fish consumption, it has been suggested that faster growth of largemouth bass hatched earlier was also due to higher fish consumption. We determined hatching-date-specific diets and growth of largemouth bass up to about 180 d old, collected in summer and fall 1987 in a North Carolina reservoir. Frequency of fish consumption for age-0 largemouth bass of all sizes tended to decrease as the growing season progressed. Largemouth bass that hatched earlier, however, were piscivorous at a younger age and maintained a higher level of piscivory late in the growing season than did fish that hatched later. Dietary differences that were hatching-date-dependent seemed to be due to seasonal decrease in prey fish availability. The growth advantage for fish hatched earlier was primarily expre...

Selectivity of Sampling Methods for Juvenile Largemouth Bass in Assessments of Recruitment Processes

Abstract Assessment of the recruitment processes of juvenile largemouth bass Micropterus salmoides has involved a variety of gears, and little consideration has been given to the biases that gear size selection may introduce. To determine the influence of collecting methods on the interpretation of cohort characteristics, we compared length distributions of juvenile largemouth bass collected with a 9-m bag seine, a hand-held electrofisher, and a traditional boom-mounted electrofisher. The hand-held electrofisher was effective for sampling all lengths of fish up to 200 mm total length and sampled smaller fish than the boom-mounted unit. Seining was effective for sampling fish shorter than 60 mm but, relative to the hand-held electrofisher, it consistently underrepresented the contribution of fish longer than 70 mm to the cohort. The boom-mounted electrofisher was effective at sampling fish longer than 150 mm, but, compared with the hand-held electrofisher, it underestimated the contribution of smaller fish...

Spawning Period and First-Year Growth of Northern, Florida, and Intergrade Stocks of Largemouth Bass

Abstract Subspecific differences in spawning period and first-year growth of largemouth bass Micropterus salmoides were investigated by examination of otoliths from experimental populations established in research ponds in Illinois. Compared with Florida largemouth bass M. s. floridanus, northern largemouth bass M. s. salmoides were spawned earlier and grew larger (total length, weight) during the first growing season. Intergrade fish exhibited characteristics of age and growth intermediate between those of the two pure parental subspecies. The observed differences in size were independent of age, indicating that first-year differences in size were enhanced by genetic differences affecting growth rate. Peak production of F1 intergrades occurred during the overlap in the northern and Florida largemouth bass spawning periods. However, F1 intergrades were produced throughout the overall period of largemouth bass spawning.

Changes in the Abundance of Two Atherinid Species after Aquatic Vegetation Removal

Abstract Brook silverside Labidesthes sicculus and inland silverside Menidia beryllina coexisted in Lake Conroe, Texas, for at least 6 years before we began our field sampling in 1980. We hypothesized that an extensive infestation of aquatic vegetation was a critical factor allowing sympatry, because introduced inland silversides have rapidly displaced endemic brook silversides in other, less-vegetated, reservoir systems. We believe that an abundant invertebrate prey base associated with the aquatic vegetation was responsible for a low level of interspecific competition for food resources between the two silverside species in Lake Conroe. After removal of vegetation in 1981–1983 by grass carp Ctenopharyngodon idella, the inland silverside population expanded and the brook silverside population declined. By 1986, brook silversides were rare in seine samples taken from, or near, the main basin of the reservoir and appeared to be restricted to tributaries and coves. Data suggest that food habits of the silve...

Movements by Young-of-Year and Yearling Largemouth Bass and Their Implications for Supplemental Stocking

Abstract Young-of-year (age-0) largemouth bass Micropterus salmoides from the Little Beaver Creek embayment of B. Everett Jordan Lake, North Carolina, were individually tagged with magnetic binary-coded wire tags in 1989 and 1990. Fish were recaptured during electrofishing and seine sampling in the year of tagging and the following year. In 1989, 529 age-0 largemouth bass were tagged, of which 40 were recaptured. Of these, only 2 of 31 age-0 and 2 of 9 yearling fish had moved out of their tagging coves. In 1990, 1,090 age-0 largemouth bass were tagged, of which 47 were recaptured. Of 15 recaptured largemouth bass that had been tagged in coves, only 2 age-0 fish had moved from their tagging coves. Of 32 recaptured largemouth bass that had been tagged outside coves, only 2 age-0 and 1 yearling fish had moved into cove areas. No tagged age-0 or yearling largemouth bass were recaptured outside the embayment. Because most fish seem to stay near their tagging site, localized supplemental stocking of fingerlings...

Effect of Aquatic Macrophyte Removal on Recruitment and Growth of Black Crappies and White Crappies in Lake Conroe, Texas

Abstract In Lake Conroe, Texas, macrophyte removal by grass carp Ctenopharyngodon idella corresponded to an increase in abundance of threadfin shad Dorosoma petenense. Subsequently, growth rates of black crappies Pomoxis nigromaculatus and white crappies P. annularis increased, and crappie recruitment to harvestable size (254 mm total length) declined by 1–2 years compared with periods when macrophyte coverage ranged from 29 to 44%. First-year growth appeared to be density-dependent for both species. Crappie year-class strength was highly variable, and no consistent trends were evident between age-1 density and macrophyte or threadfin shad abundance. If crappies depend on threadfin shad or other pelagic forage fish for food, and if these prey are negatively affected by excessive macrophyte growth, then plant control should be considered to enhance crappie growth rates.

Fishing and Natural Mortality of Adult Largemouth Bass in a Tropical Reservoir

Abstract Largemouth bass Micropterus salmoides, an intensively studied sport fish of temperate North America, has been introduced into tropical regions, but with little evaluation of fishing or natural mortality rates. Previous research in Puerto Rico suggested that annual mortality rates are high, but whether the extended spawning season (nearly 6 months annually), high angler harvest, or a combination was the cause of the elevated mortality was unresolved. Using ultrasonic telemetry, we tracked 44 adult largemouth bass over an 18-month period to quantify patterns of natural, fishing, and total mortality. Using a general capture–recapture model, we estimated the annual instantaneous rates of fishing (0.584, SE = 0.164) and natural mortality (0.310, SE = 0.122). Natural mortality varied seasonally and generally increased during periods of spawning activity; however, fishing mortality was fairly consistent throughout the study. Given the relatively high fishing mortality rate, restrictions on harvest could...