Diet Of Largemouth Bass Research Articles

Foraging specialization by the opportunistic largemouth bass (Micropterus salmoides)

The opportunistic foraging nature of largemouth bass (Micropterus salmoides) is thought to preclude it from specialization when prey resources are in abundance. Here, we describe largemouth bass foraging specialization on Chaoborus spp. Chaoborus spp. specialization was unexpected because largemouth bass is a diurnal littoral visual predator, whereas Chaoborus spp. occupy the surface waters of the pelagic zone at night and are energetically unfavorable. Largemouth bass foraging in the pelagic zone, determined by core body temperature, had significantly (p < 0.001) more Chaoborus spp. per gut (249.3) than littoral foragers (68.4). Individual largemouth bass diet consistency over time was greater than the diet consistency of random pairings, indicating that pelagically oriented largemouth bass specialize in Chaoborus spp. predation. This unusual individual foraging behavior is likely caused by heavy intraspecific competition, which leads some fish to acquire new prey search images due to prey resource limitation.

Whole-lake addition of coarse woody habitat: response of fish populations

Lakeshore residential development (LRD) reduces coarse woody habitat (CWH) in lakes resulting in negative effects on fishes. We tested whether the addition of CWH could reverse those effects. We added CWH to Camp Lake, a lake with CWH abundances similar to developed lakes, following 2 years of study of the fish populations in the reference and treatment basins. Both basins were monitored for 4 years following the manipulation. Specifically, we tested for changes in the population dynamics (densities, size-structure, growth), diet, and behavior (habitat use) of bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides). CWH addition had no discernible effect on fish population dynamics. Diet and behavioral responses were more pronounced in the treatment basin. Prey diversity and availability increased. Piscivory increased, with decreased reliance upon terrestrial prey, for largemouth bass. Habitat use was positively correlated with CWH branching complexity and abundance. Our study suggests that negative effects observed in fish populations through CWH reductions cannot be reversed in the short-term by adding CWH. We recommend that regulations governing the LRD process be protective of CWH.

Coastal Estuaries as Habitat for a Freshwater Fish Species: Exploring Population‐Level Effects of Salinity on Largemouth Bass

AbstractEstuaries are systems where marine and freshwaters interface. The largemouth bass Micropterus salmoides is a freshwater predator commonly found in the oligohaline portions of estuaries in coastal North America. As a popular recreational sport fish in estuaries, largemouth bass are caught in large numbers, but large (≥2.3‐kg) individuals are rarer than in inland (freshwater) systems. A pervasive factor affecting estuarine inhabitants is variation in salinity, which we hypothesized would represent a stress influencing largemouth bass performance. To test this, we sampled fish monthly (2002–2004) across an upstream–downstream gradient in the Mobile–Tensaw Delta of Alabama. Salinity remained negligible upstream but increased seasonally downstream. Catch per effort did not differ predictably across the upstream–downstream gradient, as would be expected if salinity influences abundance. Largemouth bass diets included more fish than invertebrates both upstream and downstream, but fish were more abundant in the diet upstream. Marine invertebrates remained an important diet component at all sites. Condition was generally high for all largemouth bass but was consistently greater downstream than upstream. Length at age 1 was greater downstream than upstream, but there were no differences for older fish. Few largemouth bass age‐4 and older were present, and survival was generally low (&lt;57%). Although growth was greater for a population of largemouth bass from the Mobile–Tensaw Delta established into a freshwater impoundment, survival remained low in the absence of coastal influences. Our results suggest that the largemouth bass in the coastal Mobile–Tensaw Delta have different growth patterns and perhaps different life history strategies than those in freshwater, which may be the result of adaptation and could have important implications for management.

Comparison of Bioenergetics Parameters from Two Spring-Fed Riverine Largemouth Bass Populations

This study applies a new bioenergetics modeling framework put forth by Walters and Essington (this volume) which estimates bioenergetics parameters and consumption rates of fishes using commonly collected size-at-age and cap- ture-recapture data from field studies. Bioenergetics model parameters and consumption rates are estimated for two popu- lations of largemouth bass Micropterus salmoides with observed differences in growth patterns. We also compare con- sumption estimates from the bioenergetics model formulated by Walters and Essington with a more commonly employed bioenergetics model. We show that bioenergetics model parameters can be estimated with limited data on size-at-age and incremental growth when informative prior distributions on metabolic parameters are used. The general bioenergetics model revealed differences in bioenergetics parameters between the two largemouth bass populations that are well sup- ported by auxiliary data on largemouth bass diets and observed prey abundance patterns. Lifetime growth and consump- tion estimates between the general bioenergetics model and Wisconsin bioenergetics model differed slightly. However, seasonal patterns in growth and consumption rates differed drastically between the two models. Estimating bioenergetics parameters using field data collected on specific populations of interests has the potential to allow for more realistic repre- sentation of seasonal growth and consumption patterns.

Effects of Striped Bass Stocking on Largemouth Bass and Spotted Bass in Lewis Smith Lake, Alabama

AbstractIntroductions of striped bass Morone saxatilis into U.S. reservoirs have caused concern among anglers that target other species owing to the perception that this predator reduces the number of other sport fish and can limit available prey supplies. Recently, this controversy arose in Lewis Smith Lake (8,583 ha), Alabama, prompting this study to examine the effects of stocking striped bass on the resident population of black bass Micropterus spp. From October 2006 to August 2007, the diets of striped bass, largemouth bass M. salmoides, and spotted bass M. punctulatus were examined in this reservoir. The density and biomass of striped bass and black bass were computed from estimates of age‐0 black bass abundance, striped bass stocking rates, growth, and survival. Bioenergetics models were used to estimate striped bass and black bass consumptive food demands. Striped bass diets (by weight) were dominated by shad Dorosoma spp. (64%), followed by crayfish Oronectes spp. (12%), while black bass and sunfish Lepomis and crappies Pomoxis spp. comprised 5% and 6% of the diet, respectively. Numerically, sunfish–crappies and black bass only comprised 0.28% and 0.16% of the diets of striped bass. The diets of largemouth bass and spotted bass (by weight) were dominated by crayfish (72% and 75%, respectively) and sunfish–crappies (21% and 9%, respectively), while shad comprised 6% and 14% of the diets, respectively. Diet overlap values between striped bass and black bass were generally low but varied seasonally among species. The highest overlap between the diets of striped bass and black bass was observed in April and June. However, the relative weights of black bass did not decline or the frequency of empty stomachs among these species did not increase during or after this time. Overall, consumptive prey demand was similar between striped bass and black bass. Bioenergetics modeling estimated striped bass consumption of shad, bass–sunfish–crappies, and crayfish averaging 14, 3, and 5 kg/ha, respectively, compared with 3, 6, and 16 kg/ha, respectively, for black bass. Shad consumption by striped bass and black bass (relative to the total annual supply) was within acceptable levels. Striped bass consumption of black bass was low, striped bass and black bass partitioned prey resources, and the temporal differences in maximum consumptive demand varied between black bass and striped bass. Thus, we found that the impact of striped bass stocking on the black bass population was minimal.

Water Mites in the Diet of Largemouth Bass

ABSTRACT Water mites (Hydracarina) are not consumed by some fish because of their distastefulness or toxicity. We obtained evidence that some individual largemouth bass (Micropterus salrnoides) specifically targeted mites as prey in a small unproductive and unexploited lake in Michigan's Upper Peninsula, USA. Bass stomachs that contained water mites tended to have high numbers of mites, with up to 780 mites in individual stomachs. Stronger evidence for foraging specialization was provided by repeated examination of stomach contents from recaptured bass; many bass contained water mites more often than would be expected by chance (one-sample t-test [H0=0], t = 3.54, P <0.0001). Also, there was no correlation between bass density and the percentage of bass consuming mites (r = 0.0183) further suggesting that foraging on mites was an individual response rather than a population strategy.

Effects of Graded Levels of Carbohydrate on Growth and Survival of Largemouth Bass, Micropterus salmoides

Abstract Excessive carbohydrates (CHO) in diets for largemouth bass (LMB), Micropterus salmoides, are suspected of accumulating glycogen in hepatocytes, which may result in liver dysfunction. This study evaluated the effect of graded levels of dietary CHO on growth, survival, and liver histology of LMB. One hundred feed‐trained advanced fingerling LMB (128.5 ± 21.5 g) were stocked into each of nine 3400‐L polyethylene tanks. Tanks were randomly assigned one of three experimental diets containing different CHO levels (13, 19, or 25% of diet). The extruded diets were approximately isonitrogenous (42% crude protein) and isocaloric (3 kcal/g energy). There were three replicate tanks per dietary treatment. Bass were fed to apparent satiation twice daily for 148 d. Survival was significantly higher (P ≤ 0.05) for fish fed the 13 and 19% CHO diets (89 and 90%, respectively) compared to those fed the 25% CHO diets (82%). Average harvest weight of fish fed the 13% CHO diet (380 g) was significantly greater (P ≤ 0.05) than for fish fed other diets. Average harvest weight of fish fed the 19% CHO diet (347 g) was significantly greater (P ≤ 0.05) than for fish fed the 25% CHO diet (310 g). Specific growth rates (%/d) were significantly higher (P ≤ 0.05) in fish fed the 13 and 19% CHO diets than in fish fed 25% CHO diet. Feed conversion ratios for fish fed the 13 and 19% CHO diets (2.3 and 2.4, respectively) were both significantly lower (P ≤ 0.05) than in fish fed the 25% CHO diet (3.6). There were no significant differences (P &gt; 0.05) in condition factor, protein efficiency ratio, hepatosomatic index, or liver glycogen concentration among fish fed the different experimental diets. Overall, mean blood glucose levels in fish fed the 13 and 19% CHO diets (61.0 and 71.2 mg/dL, respectively) were significantly lower (P ≤ 0.05) than in fish fed the 25% CHO diet (87 mg/dL). Histopathological examination of livers from fish fed the three diets was used to score the degree of vacuolization of hepatic tissues (0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe). Regression of vacuolization scores on dietary CHO levels was statistically significant (P ≤ 0.05) and indicated a direct positive relationship between liver vacuolization and dietary CHO level (R2 = 0.57). These data indicate that LMB grow faster and use feeds more efficiently when CHO are maintained at &lt;20% of diet. CHO levels &gt;20% negatively impacted liver histology, but a liver tissue analyses did not document glycogen accumulation.

Digestibility of plant protein-based diets by largemouth bassMicropterus salmoides

Commercial farming of carnivorous fish demands the reduction of environmental impact of feeds; that requires minimal use of dietary animal protein. This study investigated the digestibility of diets formulated exclusively out of plant protein, added feed attractants, by the carnivore largemouth bass, Micropterus salmoides. Juvenile largemouth bass (14.0 ± 1.0 cm) conditioned to accept artificial, dry feed were confined in polypropylene cages and fed ad libitum in three daily meals, seven experimental diets containing varying levels of vegetable and animal protein sources, added of different feed stimulants. After last daily meal, cages were transferred to cylindrical–conical-bottomed, 200-L aquaria, where faeces were collected by sedimentation into refrigerated containers, preserved and later analysed for chemical composition. Soybean meal can be used as partial substitute of animal protein in diets for largemouth bass; the poultry by-product meal shows as a good option as animal protein source in these rations. Control treatment – 50PP : 50AP – yielded best performances; the need for the use of fish meal in the formulation for carnivorous diets is, at least, questionable. Results of the digestibility trials demonstrated the importance of determining the diet digestibility, if precision in the formulation of least-cost feeds for carnivorous fish is the ultimate goal.

Insulin Response of Largemouth Bass to Glucose, Amino Acid, and Diet Stimulation

AbstractInvestigation of the dietary requirements of largemouth bass Micropterus salmoides has intensified because of the popularity of this species. To determine commercial diets containing carbohydrate concentrations that are not detrimental to the health and survival of largemouth bass, we examined the effects of carbohydrate loads on insulin response. This study was intended to characterize the insulin response of largemouth bass to diet, glucose, and amino acids. Pellet‐trained largemouth bass were either orally stimulated with glucose, lysine, arginine, or methionine or fed a commercial pelleted diet or a “natural” diet of golden shiners Notemigonus crysoleucas, then bled over time to ascertain their insulin response. Insulin response was correlated with glucose response, the insulin responses lagging slightly behind increases in blood glucose concentration. Greater increases in blood glucose were accompanied by sharper, quicker insulin responses. Glucose (4.8 ± 0.3 ng insulin/mL) and arginine (5.4 ± 0.4 ng/mL) stimulation evoked the greatest mean insulin responses at 60 min postadministration; lysine (2.1 ± 0.3 ng/mL) also produced elevated insulin responses. The pelleted diet stimulated an intermediate response, whereas the diet of golden shiners produced the lowest insulin response. This study was intended to determine how the carbohydrate content of diets and subsequent influences on insulin response affect the health of largemouth bass. Because of confounding effects and interference from arginine and lysine in the diet, insulin response is not suitable for determining appropriate carbohydrate loads in largemouth bass diets. At this time, histological data and liver glycogen concentration should be used to determine appropriate carbohydrate loads in commercial diets.

Changes in Diet and Food Consumption of Largemouth Bass Following Large-scale Hydrilla Reduction in Lake Seminole, Georgia

Largemouth bass Micropterus salmoides Lacepede growth (in length) increased an average of 14% and bioenergetics modeling predicted a 38% increase in total annual food consumption following a large-scale reduction of hydrilla Hydrilla verticillata L.f. Royle in Spring Creek, a 2,343-ha embayment of Lake Seminole, Georgia. Coverage of submersed aquatic vegetation (SAV) declined from 76% to 22% in 1 year due to a drip-delivery fluridone treatment. In contrast, largemouth bass growth only increased an average of 4% and bioenegetics modeling predicted a 13% increase in total food consumption over the same time period in the Chattahoochee River embyament, where SAV coverage naturally declined from 26% to 15%. Diets were collected from a total of 4,409 largemouth bass over a 2.5-year period in the two embayments; the primary diet item (by weight) for largemouth bass in both embayments was sunfish (mostly Lepomis spp.). Diets before and after SAV reduction were generally similar for fish greater than stock-size (≥203 mm) in the Spring Creek arm; however, fewer invertebrates were consumed after SAV reduction. Low diet similarity was observed in smaller fish, caused by a decline in consumption of grass shrimp and sunfishes and an increase in use of damselflies, shiners Notropis spp., and topminnows Fundulus spp. after SAV reduction. Diets were similar between the same time periods for all sizes of fish in the Chattahoochee River arm. These results agreed with many laboratory results describing the effects of aquatic plant density on largemouth bass food consumption and growth, and demonstrated that increased predation efficiency resulting from decreased plant abundance was likely a stronger factor determining growth rates than any potential diet shift that may occur as a result in vegetation decline.

Evaluation of the Ecological Compatibility of Butterfly Peacock Cichlids and Largemouth Bass in Puerto Rico Reservoirs

AbstractIntroduction of peacock cichlids Cichla spp. into tropical and subtropical systems where they can successfully overwinter and reproduce has been a common practice in fisheries management. We evaluated the compatibility of nonnative butterfly peacock cichlids Cichla ocellaris and largemouth bass Micropterus salmoides in Puerto Rico reservoirs using (1) controlled juvenile interaction experiments, (2) examination of hatching periodicity and diet overlap of juveniles in a reservoir environment, and (3) comparison of adult catch data from 10 Puerto Rico reservoirs. In the juvenile interaction experiments, butterfly peacock cichlid juveniles in ponds with largemouth bass had slower growth in length (P = 0.020) and weight (P = 0.003) and lower survival (P = 0.002) than in ponds with only butterfly peacock cichlids. In reservoirs, largemouth bass spawning typically occurred 2–3 months before butterfly peacock cichlid spawning, which resulted in substantial size differences between the juveniles of the two species. Butterfly peacock cichlids fed almost exclusively on threadfin shad Dorosoma petenense; the largemouth bass diet included threadfin shad but was much more diverse. Correlation coefficients were negative for comparisons of adult largemouth bass and butterfly peacock cichlid catch rates in the reservoirs sampled. Pooled catch data from all reservoirs showed a significant inverse relationship in relative abundance (P = 0.026). Catch rates from reservoirs with and without butterfly peacock cichlid populations indicated that largemouth bass densities were higher in single‐predator systems (mean = 85.1/h) than in dual‐predator systems (9.8/h).

Evaluation of Plant and Animal Source Proteins for Replacement of Fish Meal in Practical Diets for the Largemouth Bass Micropterus salmoides

Two feeding trials were conducted with juvenile largemouth bass Micropterus salmoides to evaluate alternative plant and animal source proteins for their ability to replace fish meal in practical diets. The first trial was designed to identify the most promising candidates. The second trial was conducted to evaluate how much of the fish meal could be replaced by those candidates. In Study 1, feed-trained largemouth bass (3.1 ± 0.7 g) were randomly stocked into 18114-L glass aquaria at 25 fish per aquarium. Fish were fed one of six experimental diets, each containing approximately 38% crude protein and 10% crude lipid, to apparent satiation twice daily. The control diet (CTL) contained 30% fish meal and 34.5% soybean meal. Diets 2–6 each contained 15% fish meal and at least 34.5% soybean meal with the remainder of the protein made up of either meat and bone meal (MBM), soybean meal (SBM), poultry by-product meal (PBM), a 50150 mixture of blood meal and corn gluten meal (BM/CG), or 50150 mixture of hydrolyzed feather meal and soybean meal (FMISBM). There were three replicate aquaria per dietary treatment. After 12 wk, there was no significant difference (P > 0.05) among treatments in survival which averaged 92% overall. Only fish fed the PBM or BM/CG diets had average individual weights and feed conversion efficiencies that were not significantly different (P > 0.05) from the control diet (CTL). In Study 2, the formulation of the control diet (CTL) remained the same. Based on their performance in the first trial, PBM and BM/CG were chosen to now replace 75 or 100% of the fish meal. Fish were stocked at an average weight of 6.9 ± 1.7 g. After 11 wk, fish fed diets containing the BM/CG mixture at both levels were significantly smaller (P 5 0.05) than fish fed other diets and at 100% replacement survival was reduced. Fish fed diets containing poultry meal as the primary protein source performed as well as those fed the control diet (CTL). It appears that PBM can completely replace fish meal in diets for juvenile largemouth bass without adverse effects on growth, feed efficiency, or body composition.

Interactions between Walleyes and Four Fish Species with Implications for Walleye Stocking

AbstractWe used a number of different data sets and four criteria to evaluate evidence of competition and predation between walleye Sander vitreus and northern pike Esox lucius, muskellunge E. masquinongy, smallmouth bass Micropterus dolomieu, and largemouth bass M. salmoides in northern Wisconsin lakes. The four criteria were as follows: (1) indices of population abundance were inversely related, (2) two species had shared resources or one species preyed on the other, (3) competition or predation was strong enough to produce a measurable effect, and (4) experimental manipulations produced results consistent with the hypothesis of competition or predation. Using these criteria, we identified which species interact most strongly with walleyes, determined the most likely mechanism for interaction (predation, competition, or both), and characterized the effects of walleye stocking on these species. Largemouth bass was the only species that strongly interacted with walleyes: (1) indices of largemouth bass and walleye population abundance were inversely related in lakes with self‐sustaining walleye populations; (2) the diet of largemouth bass included juvenile walleyes; (3) walleye growth was positively related to indices of largemouth bass abundance; and (4) survival of stocked walleyes was negatively related to indices of largemouth bass abundance, and indices of largemouth bass abundances increased as an index of walleye stocking intensity increased. A bioenergetics analysis of one lake that was stocked with 39,300 juvenile walleyes, but also has some natural reproduction of walleyes, suggested that the largemouth bass population could consume up to 82,500 juvenile walleyes per year. Our findings suggest that largemouth bass interact strongly with walleyes through predation, that they can limit the survival of stocked walleyes, and that walleye stocking can result in increased largemouth bass populations. Therefore, management goals seeking to simultaneously maximize largemouth bass and walleye populations may be unrealistic.

Habitat and Diet Partitioning between Shoal Bass and Largemouth Bass in the Chipola River, Florida

Abstract We investigated the macrohabitat use, microhabitat use, and food habits of shoal bass Micropterus cataractae and largemouth bass M. salmoides in the upper Chipola River, Florida. We electrofished two macrohabitats (pools and shoals) during the summer (May–August) and fall (September–December) of 1999 and 2000. The ratio of shoal bass to largemouth bass differed among macrohabitats, being highest in the shoals and lowest in the pools. Age-0 and adult (age-1 and older) shoal bass were collected in areas of higher-than-average percentages of rocky substrate in both shoals and pools. Age-0 and adult largemouth bass were associated with areas of reduced current velocity and those with higher-than-average amounts of woody debris. Though the diets of age-0 and adult shoal bass and largemouth bass were similar, a few differences were apparent. Age-0 largemouth bass diets contained grass shrimp Palaemonetes spp., whereas age-0 shoal bass diets contained mostly mayflies (order Ephemeroptera: families Baeti...

Diet dynamics of the adult piscivorous fish community in Spirit Lake, Iowa, USA 1995–1997

Abstract – Diets of adults of six important piscivorous fish species, black crappie Pomoxis nigromaculatus, largemouth bass Micropterus salmoides, northern pike Esox lucius, smallmouth bass Micropterus dolomieui, walleye Stizostedion vitreum, and yellow perch Perca flavescens were quantified in Spirit Lake, Iowa, USA from May to October in 1995–1997. Forty‐one prey taxa were found in the diets of these species, including 19 species of fish. The most important prey taxa overall were yellow perch, amphipods and dipterans. Diets of northern pike and walleye were dominated by yellow perch. Largemouth bass diets included large percentages of both yellow perch and black bullhead Ameiurus melas. Smallmouth bass diets included large percentages of both yellow perch and crayfish. Black crappie and yellow perch diets were dominated by invertebrates, primarily amphipods and dipterans. There were pronounced differences in diets among species, among size classes within species and over time. Most of the dominant prey taxa we documented in the diets of piscivorous species were in accordance with previous studies, but a few deviated significantly from expectations. Many of the temporal diet changes were asynchronous among piscivorous species and size classes, suggesting different responses to common prey resources over time.

Largemouth Bass Predation on Stocked Striped Bass in Smith Mountain Lake, Virginia

First-year survival of striped bass Morone saxatilis stocked into lakes and reservoirs is often poor, but causes of mortality have not been determined. We quantified losses of stocked, age-0 striped bass to predation by largemouth bass Micropterus salmoides in Smith Mountain Lake, Virginia, where first-year striped bass survival averages 25% and the largemouth bass is the principal littoral piscivore. To examine their diet composition and abundance, largemouth bass were sampled throughout the month following the stocking of striped bass in two coves in 1994 and one cove in 1995. We used a bioenergetics model to extrapolate total prey consumption over the month and the numerical contribution of striped bass to the largemouth bass diet. Only 14 striped bass were recovered in 1,147 largemouth bass stomachs over the 2 years. Percentage losses of striped bass to largemouth bass predation were 0.1% in each cove in 1994 and 3.0% in the single cove in 1995. Predation may have been constrained by the small size (24–74 mm) of striped bass and by the availability of spawning alewives Alosa pseudoharengus as alternate prey (i.e., adult alewives constituted the bulk of the largemouth bass summer diet). In pool experiments, largemouth bass ate significantly more alewives than striped bass when both prey were available; their consumption of striped bass increased in trials where alewives were absent. Abundance of alternate prey and their use by largemouth bass should be assessed before selecting striped bass stocking sites. Spreading the stocking over multiple sites to reduce predation mortality was unnecessary in Smith Mountain Lake.

Weak trophic interactions between large predatory fishes and herpetofauna in the channelized Kissimmee River, Florida, USA

We tested the hypothesis that large predatory fishes are major predators of amphibians and reptiles along littoral ecotones by examining the diets of 70 bowfin (Amia calva), 22 chain pickerel (Esox niger), 235 Florida gar (Lepisosteus platyrinchus), 258 largemouth bass (Micropterus salmoides), and 46 warmouth (Lepomis gulosus) collected from enhanced and non-enhanced portions of the channelized Kissimmee River, Florida, USA. Only six bowfin (9%) and four bass (2%) preyed upon herpetofauna. The diet of bowfin included peninsula newts (Notopthalmus viridescens piaropicola), greater sirens (Siren lacertina), and striped crayfish snakes (Regina alleni), whereas the diet of largemouth bass included peninsula newts, striped crayfish snakes, and stinkpot turtles (Kinosternum odoratus). No individual predator consumed more than one type of herpetofauna. The higher percentage of herpetofauna consumed by bowfin reflects this species catholic feeding habits. Prey size was positively correlated with predator size. Eighty percent of fishes that preyed upon herpetofauna were collected from non-enhanced portions of the river, which may reflect lower abundance of preferred prey in these disturbed habitats. Overall, it does not appear that amphibians and reptiles are an important part of the piscine food web in the channelized Kissimmee River.

Inter-Annual and Size-Related Differences in the Diets of Three Sympatric Black Bass in an Oklahoma Reservoir

ABSTRACT We quantified the diets of juvenile and adult largemouth bass (Micropterus salmoides), smallmouth bass (M. dolomieu), and spotted bass (M. punctulatus) in Skiatook Lake, Oklahoma in 1997 and 1999 to assess inter-annual and size-related differences in food resource use. The diets of juvenile and adult largemouth bass consisted mainly of fish, but juveniles consumed a significant number of dipterans during both years. Smallmouth bass and spotted bass adult diets were similar to each other in both years; crayfish and fish were the predominant food items. Juvenile smallmouth bass and spotted bass were mainly insectivorous with fish and crayfish also making up a proportion of the diet. Mean diet overlap was greater in 1999 compared to 1997. These findings are consistent with the expanding population hypothesis that predicts increased niche overlap.

Trophic ecology of largemouth bass and northern pike in allopatric and sympatric assemblages in northern boreal lakes

Largemouth bass (Micropterus salmoides) and northern pike (Esox lucius) are top predators in the food chain in most aquatic environments that they occupy; however, limited information exists on species interactions in the northern reaches of largemouth bass distribution. We investigated the seasonal food habits of allopatric and sympatric assemblages of largemouth bass and northern pike in six interior lakes within Voyageurs National Park, Minnesota. Percentages of empty stomachs were variable for largemouth bass (38-54%) and northern pike (34.7-66.7%). Fishes (mainly yellow perch, Perca flavescens) comprised greater than 60% (mean percent mass, MPM) of the northern pike diet during all seasons in both allopatric and sympatric assemblages. Aquatic insects (primarily Odonata and Hemiptera) were important in the diets of largemouth bass in all communities (0.0-79.7 MPM). Although largemouth bass were observed in the diet of northern pike, largemouth bass apparently did not prey on northern pike. Seasonal differences were observed in the proportion of aquatic insects (P = 0.010) and fishes (P = 0.023) in the diets of northern pike and largemouth bass. Based on three food categories, jackknifed classifications correctly classified 77 and 92% of northern pike and largemouth bass values, respectively. Percent resource overlap values were biologically significant (greater than 60%) during at least one season in each sympatric assemblage, suggesting some diet overlap.

Assessing the Contribution of Anadromous Herring to Largemouth Bass Growth

Juvenile anadromous river herring (alewife Alosa pseudoharengus and blueback herring A. aestivalis) spend the first 3 to 7 months of life in headwater lakes of coastal systems. Systems that support herring often produce trophy largemouth bass Micropterus salmoides. Even though biologists, managers, and anglers have speculated about the value of anadromous herring as a key prey for resident predators, the contribution that herring make to the diets of these predators has not been assessed. Herein, we quantified largemouth bass diets in two coastal lakes, Santuit and Coonamessett ponds, that contained anadromous herring, and we used bioenergetics modeling to evaluate the importance of herring prey to largemouth bass growth. During May through November 1994, largemouth bass diets consisted of various fish species, crayfish, and other invertebrates. Although not the most important prey overall, herring were the most important fish prey consumed in both lakes based on number of individuals consumed. In both lakes, herring were primarily eaten by largemouth bass that were fewer than 300 mm in total length after mid-August. Coonamessett Pond largemouth bass ate more herring and other fish prey and achieved better growth than did those in Santuit Pond. Bioenergetics modeling simulations revealed that water temperature does not explain the presence of trophy largemouth bass in southeastern Massachusetts. Because largemouth bass grow better on a diet that includes herring, we conclude that juvenile herring are an energetically valuable and a potentially key prey for largemouth bass. However, factors other than energetics mediate the use of herring by these resident predators. Further investigations into spatial dynamics, size structure, and foraging behavior are necessary to understand the mechanisms that drive interactions between largemouth bass and anadromous herring.