White Crappie Research Articles

Correlation between Histological and Behavioral Measures of Visual Acuity in a Zooplanktivorous Fish, the White Crappie <i>(Pomoxis annularis)</i>

Estimates of visual acuity in a pelagic freshwater zooplanktivorous fish, the white crappie (Pomoxis annularis, Centrarchidae), were made using a behavioral measure, the maximum observed prey pursuit distance (MxPD), and a histological measure, the density of cone cells in the retina. The greatest number of pursuits occurs in the 0-30 degrees wedge of the visual field; 87% of all pursuits occur in the first 40 degrees. The longest pursuits (200 mm) also occur in this area and generally get shorter from 0 to 180 degrees (from forward-directed) in the visual field. Consistent with the behavioral results, the largest number of cone photoreceptors (13,000/mm2) is found in the far temporal retina along the eye's horizontal meridian. Cone cell densities in the corresponding region of the nasal retina are approximately half this value. The number of cones decreases dorsally and ventrally from the horizontal meridian. Although the absolute values of visual acuity calculated from cone cell topography (i.e. MxPDs of 500 mm) are 2-3 times greater than those observed behaviorally (i.e. MxPDs of 200 mm), the trends in visual acuity across the visual field obtained from both measures are consistent. We suggest that overestimates of visual acuity obtained from cone cell counts alone result from this measure's not accounting for, among other properties of the nervous system, cone cell convergence onto ganglion cells and higher brain centers. Behavioral measures of visual acuity are, therefore, likely to yield a more accurate estimate of an animal's visual abilities.

Incidence of Sport Fishes in the Commercial Fish Catch from Kentucky Lake, Kentucky and Tennessee

On-board observers accompanied commercial fishermen on Kentucky Lake and recorded the occurrences of sport fishes in gill-net, bait-line, and hoop-net catches. Sport fishes constituted 0.5% of the total catch on bait lines, 0.1% in hoop nets, and 3.9% in gill nets. The most common incidental sport species caught were freshwater drum Aplodinotus grunniens and small yellow bass Morone mississippiensis on bait lines and sunfishes Lepomis spp. in hoop nets. The percentage of sport fishes in gill nets decreased as mesh size increased. Sauger Stizostedion canadense and white crappie Pomoxis annularis were the most common species in gill nets and constituted 92% of the incidental sport-fish catch. We estimated an incidental sport-fish catch in gill nets of 2.1 fish/1,000 m of net, whereas commercial fishermen reported 0.7 fish/1,000 m. On the basis of our estimates of incidental catches from all commercial gears, we concluded that the capture of sport fishes at the extant fishing intensity did not pose a threat to sport-fish populations.

Flexible search tactics and efficient foraging in saltatory searching animals

Foraging is one of the most important endeavors undertaken by animals, and it has been studied intensively from both mechanistic-empirical and optimal foraging perspectives. Planktivorous fish make excellent study organisms for foraging studies because they feed frequently and in a relatively simple environment. Most optimal foraging studies of planktivorous fish have focused, either on diet choice or habitat selection and have assumed that these animals used a cruise search foraging strategy. We have recently recognized that white crappie do not use a cruise search strategy (swimming continuously and searching constantly) while foraging on zooplankton but move in a stop and go pattern, searching only while paused. We have termed thissaltatory search. Many other animals move in a stop and go pattern while foraging, but none have been shown to search only while paused. Not only do white crappie search in a saltatory manner but the components of the search cycle change when feeding on prey of different size. When feeding on large prey these fish move further and faster after an unsuccessful search than when feeding on small prey. The fish also pause for a shorter period to search when feeding on large prey. To evaluate the efficiency of these alterations in the search cycle, a net energy gain simulation model was developed. The model computes the likelihood of locating 1 or 2 different size classes of zooplankton prey as a function of the volume of water scanned. The volume of new water searched is dependent upon the dimensions of the search volume and the length of the run. Energy costs for each component of the search cycle, and energy gained from the different sized prey, were assessed. The model predicts that short runs produce maximum net energy gains when crappie feed on small prey but predicts net energy gains will be maximized with longer runs when crappie feed on large prey or a mixed assemblage of large and small prey. There is an optimal run length due to high energy costs of unsuccessful search when runs are short and reveal little new water, and high energy costs of long runs when runs are lengthy. The model predicts that if the greater search times observed when crappie feed on small prey are assessed when they feed on a mixed diet of small and large prey, net energy gained is less than if small prey are deleted from the diet. We believe the model has considerable generality. Many animals are observed to move in a saltatory manner while foraging and some are thought to search only while stationary. Some birds and lizards are, known to modify the search cycle in a manner similar to white crappie.

Distribution of Upper and Middle Ohio River Fishes, 1973–1985: I. Associations with Water Quality and Ecological Variables

ABSTRACT More than 200,000 adult and juvenile fishes of 100 species were collected near five electric generating plants located in the upper and middle Ohio River during 1973 through 1985. Catches were dominated by Notropis atherinoides, Dorosoma cepedianum, Pimephales notatus, Ictalurus punctatus, Cyprinus carpio, Lepisosteus osseus, Lepomis macrochirus, Pomoxis annularis, Notropis blennius, and Aplodinotus grunniens. Twenty-nine species occurred with greater frequency in the upper Ohio River, whereas 17 species were found predominately in the middle Ohio River sampling areas. Classification of these species based upon mode of reproduction, habitat preference, and mode of feeding indicated a distinct prevalence of species typically associated with smaller, free-flowing streams at upper Ohio River sampling sites. Species typically found in large, slow-moving water bodies dominated at middle Ohio River sites. These fish distributional trends may be partially related to significant upper-middle Ohio River d...

Distributional Properties of the Number of Moves Index of Diversity

The large-sample distribution of the number of moves index of diversity is shown to be approximately normal under the general assumption of asymptotic normality of the species frequencies. Its distribution can be fit by the beta distribution for completely even underlying populations. Exact smallsample moments are computed assuming multinomial frequencies with an equiprobable and a broken-stick model. The scaled version of the index appears to be biased upward for small samples from uneven populations when the number of species in the population is unknown. An application is illustrated for comparing the population diversities of the prey consumed by white crappie at different lake depths.

Allozymic Differences between Black and White Crappies

Abstract Allozymic variation was examined from two allopatric and two sympatric populations of white crappie Pomoxis annularis and black crappie P. nigromaculatus in Texas. Twenty-five presumptive enzyme-encoding loci were assayed. Nine loci were monomorphic for the same alleles in both species. Eleven loci were characterized by electromorphs that allowed discrimination between these two species. The fixed allelic differences between the species provide an accurate means for identifying artificially propagated F1 crappie hybrids, evaluating subsequent reproductive success, and assessing introgression where both species are stocked together or where hybrid crappies are stocked into resident populations of black or white crappie.

Effects of Stocking Hybrid Striped Bass in Spring Lake, Illinois

Spring Lake, a 101-hectare impoundment that supplies potable water to Macomb, Illinois, was stocked with hybrid striped bass (striped bass Morone saxatilis ♀ x white bass M. chrysops ♂) from 1980 through 1985 at rates of 20-30 fish/hectare. Fish from the 1982 stocking reached the 432-mm minimum legal length in 28 months. Fish stocked when they were 20 mm long in June grew better and had higher survival rates than those stocked at larger sizes or later in the summer. Hybrid striped bass ate primarily gizzard shad Dorosoma cepedianum. Adult largemouth bass Micropterus salmoides, white crappies Pomoxis annularis, and channel catfish Ictalurus punctatus also relied heavily on gizzard shad, whereas juveniles fed mainly on invertebrates. Only white crappies showed any major seasonal change in food habits. By the end of 1985, white crappies were attaining a length of 200 mm 1 year earlier than in 1980. Numbers of white crappies and average sizes increased while fishing pressure and catches of other target species remained relatively unchanged. Some spillway loss of hybrids occurred.

Minimum Tailwater Flows in Relation to Habitat Suitability and Sport-Fish Harvest

Abstract The instream flow needs of four sport fishes (rainbow trout Salmo gairdneri, channel catfish Ictalurus punctatus, smallmouth bass Micropterus dolomieui, and white crappie Pomoxis annularis) were evaluated in the tailwater below Green River Lake, Kentucky. The Newcombe method, a simple procedure developed in British Columbia that is based on the distribution of water depths and velocities at various flows, was used to predict usable habitat at seven flows. Predicted usable habitat was two to six times greater for rainbow trout than for any of the other species at all flows. Angler harvest corresponded to the predicted abundance for rainbow trout and smallmouth bass, but the catch of channel catfish and white crappies was seasonally greater than expected. The presence of the dam and reservoir apparently disrupted the normal movement and feeding patterns of these species and periodically overrode the relation between usable habitat and abundance assumed in the Newcombe method. The year-round minimum...

A New View of the Predation Cycle of a Planktivorous Fish, White Crappie (Pomoxis annularis)

Predators are often categorized as either cruise or ambush feeding strategists. We present evidence that white crappie (Pomoxis annularis) are neither. Instead, the crappie swim intermittently and search only when stationary. If the crappie searched while swimming, one would expect the run speeds to be slower than the pursuit speeds, but no difference was found between these two measurements. Assuming that prey are located while swimming, a foreshortening of runs prior to pursuit would also be expected, but again, none was detectable. The duration of the search pause appears to be related to the detectability of the prey. Crappie also search during the pause immediately following the attack and ingestion of a prey item. The observation that the probabilities of detecting and pursuing a prey following a run or an attack do not differ significantly supports this conclusion. Also, the duration of the pause following a run or attack does not differ significantly over a wide range of temperatures. If these views are correct, white crappie could not forage optimally by either deleting located prey items from the diet or minimizing handling time. What they appear to be doing is creatively managing their search time.

A Buoyant Pop Net for Accurately Sampling Fish at Artificial Habitat Structures

Abstract We developed and evaluated the efficiency of a remotely operated pop net for sampling the entire fish assemblage associated with fish-attracting structures. The pop net collected an average of 99% of subadult and adult bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides available to capture in pool tests conducted at 3–13°C and various light intensities. There was no evidence of species or size selectivity, and the fish showed little increase in gear avoidance when they were sampled at the pool attractor six times over 3 d. Capture efficiency of bluegills and white crappies Pomoxis annularis was 100% in 13 trials in a reservoir. The pop net was highly reliable in field use; most failures were due to disturbance of the firing mechanism by anglers.

A Comparison of the Otolith and Scale Methods for Aging White Crappies in Oklahoma

Abstract Scales and otoliths (sagittae) were taken from a sample of 137 white crappies (Pomoxis annularis) collected by fyke netting from Ft. Supply Reservoir, Oklahoma, in November 1982. Scales and otoliths from each fish were aged independently by three experienced scale readers, none of whom had prior experience aging otoliths. The average percent error and coefficient of variation of the scale method was approximately seven times greater than for the otolith method, indicating a greater degree of precision for the otolith method. No differences were observed in back-calculated lengths derived from measurements obtained from the right versus left otolith. No significant differences in back-calculated lengths up to age 3 for a given year class sampled in successive years were observed for white crappies aged by the otolith method. These results indicate that age and growth data generated from the otolith method would be sufficiently consistent for biologists to recognize yearly trends in growth variatio...

Apparent size choice of zooplankton by planktivorous sunfish: exceptions to the rule

Choice of the apparently largest prey has been implicated as an important component of the size choice behavior of several planktivorous fish species. In this study we describe the effect of several aspects of prey placement, apparent and absolute size, and motion on the choice behavior of bluegill or white crappie. In binary choice experiments, bluegill usually choose Daphnia prey on the basis of apparent size. However, when both prey were close to the fish and the absolutely larger prey was apparently smaller, the fish commonly chose the absolutely larger. The horizontal placement of two prey also altered choice such that the more forward directed prey was chosen even when apparently smaller. White crappie, when offered a choice between a diaptomid copepod or daphnid prey, chose the daphnid most of the time. Bluegill sunfish offered moving versus non-moving heat-killed daphnids commonly chose the one in motion. Apparent size choice is still a good overall describer of bluegill and white crappie prey choice, but it is not the only mechanism involved in prey choice behavior of these fish.

Evidence of Two Feeding Subpopulations of White Crappie (Pomoxis annularis) in Rend Lake, Illinois

ABSTRACT Trap net samples of white crappie were collected in the spring from Rend Lake, Illinois, from 1978 through 1983. Analyses of age, growth, length-frequency, and diet reveal a dominant, slower-growing 1978 year class and two sub-populations, separated by growth rate and feeding behavior. At ages II–VI crappie feeding on fish have back-calculated total lengths 10.1, 27.6, 42.6, 58.9, and 63.2 mm greater than those of crappie of the same age feeding on an invertebrate diet.

Trophic Dynamics of a Nebraska Black Crappie and White Crappie Population

Abstract Diet variations of black crappie (Pomoxis nigromaculatus) and white crappie (Pomoxis annularis) were investigated at Hayes Center State Lake, a turbid 20-hectare state lake in southwest Nebraska. Zooplankton and insects accounted for most of the diet of all black crappie and of white crappie less than 200 mm long. The daily ration of planktophagic crappie declined to 1.3% as both species approached a length of 200 mm. Black crappie longer than 200 mm did not convert to fish and the daily ration declined to 0.8%. The dietary shift of white crappie to fish significantly increased the average volume of food as the daily ration increased to 1.6 and 2.9% at 200-249 and ≳ 250 mm, respectively. Crappie growth and survivorship were affected by the nature of the food. White crappie were 2.4 times more numerous and grew faster with improved survival at Age IV compared to the less dense black crappie population. Mortality rates of black crappie related positively to their size and water temperature during t...

Responses of White Crappie and Black Crappie to Threadfin Shad Introductions in a Lake Containing Gizzard Shad

Abstract Osage State Fishing Lake, Kansas, was stocked with threadfin shad (Dorosoma petenense) at a density of 12.5/hectare in May 1980 and 25/hectare in May 1981 to determine their impact on small lake crappie populations in Kansas. No winterkilled threadfin shad were found in 1980 but, in December 1981, winterkilled threadfin shad ranged from 39 to 120 mm TL. During 1980, the mean growth increment for Age-1 white crappie (Pomoxis annularis) was 150 mm, a 67-mm increase over the mean increment for the 1974-1978 year classes. The mean change in growth increment for Age-2 and -3 white crappie in 1980 was +44 mm and +7 mm, respectively. Black crappie (Pomoxis nigromaculatus) mean growth increased 3 mm for Age 1, but increased 30 mm for Age-2 and 19 mm for Age-3 fish. Doubling the stocking density of threadfin shad did not sustain the increased growth of crappie in 1981 and may have increased competition for zooplankton with young crappie. Mean spring condition factor (Wr) of white crappie greater than 200 ...

Characteristics of a Crappie Population in an Unfished Small Impoundment Containing Northern Pike

Abstract Desirable black crappie (Pomoxis nigromaculatus) and white crappie (Pomoxis annularis) populations were documented in a small impoundment in Colorado. Individuals 250 mm long and longer comprised 21% of the black crappies and 44% of the white crappies 130 mm long and longer. Mean relative weight (Wr) information indicated that crappie were in good condition and growth rates were average. Northern pike (Esox lucius) population estimates for 550-mm long and longer individuals varied from 119 to 217 fish during the 1973-1980 sampling period. Biomass of northern pike 550 mm long and longer was estimated to be 18.4 kg/hectare in 1980. Northern pike predation may help maintain desirable crappie populations in small impoundments.

Feeding Ecology of Young White Crappie in a Kansas Reservoir

White crappie (Pomoxis annularis) are a valuable sport fish, but they have received little ecological study. They are piscivorous when large (greater than 16-17 cm TL) but are almost completely planktivorous when small. We studied the location and periodicity of crappie feeding in a series of midwater trawl studies in a Kansas reservoir and found crappie between 8 and 17 cm long to be wholly pelagic. Crappie were distributed throughout most depths during the cool times of the year but were grouped more vertically during the warmer months-in part because of the anaerobic hypolimnion extending up to the 5-m depth. Crappie rarely fed at night and fed entirely on zooplankton during the day. Daphnia, even when relatively sparse, made up much of the diet whereas diaptomid copepods were relatively rare. Feeding rates of crappie ranged from 20 to 200 prey per hour when preying on zooplankton during the morning. These rates were estimated to provide sufficient energy for small crappie (5-20 g) but only marginal energy for larger fish. The larger crappie seemed to reduce energy expenditure by feeding in the cooler metalimnion during the day. However, all crappie spent the summer evening hours in the warmer epilimnion. The reason for this seemingly inefficient evening distribution is unknown.

Vertebral abnormalities in white crappies, Pomoxis annularis Rafinesque, from Lake Decatur, Illinois, and an investigation of possible causes

Crappie, Pomoxis annularis, from Lake Decatur, Illinois, were reported to have a high incidence of backbone deformities, an investigation was initiated to determine both the mechanism of vertebral injury and the causative agent. Three groups of fish were collected: normally shaped and abnormally shaped crappies from Lake Decatur and control fish from abnormally shaped crappies from Lake Decatur and control fish from nearby Lake Sangchris. Analysis of organic and inorganic residue levels in fish tissue revealed no significant levels of contaminants in any of the three groups. Evaluation of the mechanical properties, biochemical composition, and density characteristic of vertebral bone showed no significant difference between the three groups. A myxosporidean parasite, found in both normal and abnormally shaped crappies from Lake Decatur, may have been a contributing factor leading to the spinal deformities. We believe that a short‐term exposure to organophosphate insecticides, may have occurred causing muscular contractions and resulting in vertebral damage and abnormally shaped fish.

The Development and Field Test of a Tactical Model of the Planktivorous Feeding of White Crappie (Pomoxis Annularis)

A computer model was developed to predict the feeding selectivity of planktivorous white crappie (Pomoxis annularis) from a known distribution of zooplankton. The model was based on the assumption that each predation event could be subdivided into a series of independent steps: prey location, pursuit, attack, and retention. The probability that white crappie successfully completed each step was determined for potential zooplankton prey species in a series of laboratory experiments. The four steps were then incorporated into a stochastic model where the probability of a particular prey type being consumed is equal to the product of the probabilities of the individual steps. The model was field tested by sampling fish, zooplankton, and physical parameters from discrete depth strata in a small reservoir on nine dates from October 1978 through November 1979. The model proved to be very accurate at predicting the species and size distribution of the ingested prey across the range of light intensities, turbidities, temperatures, and zooplankton densities encountered. Prey consumption could not be characterized as simply size selective; rather, it reflected the selectivity expressed at each step in the feeding cycle.

Similarities in Avoidance Temperatures of Freshwater Fishes

A statistical analysis of new and published data revealed strong geographic similarities in laboratory-determined avoidance temperatures of several freshwater fishes. Validated regression models developed from our laboratory data predicted avoidance temperatures, within specified variation, of species from other areas. Four cyprinids, two ictalurids, seven centrarchids, and two percids were tested. Species within each family showed similar avoidance temperatures. An exception was white crappie, Pomoxis annularis, which avoided lower temperatures than other centrarchids. Acclimation temperature was the most significant predictor variable. No significant differences of practical value were observed in avoidance temperatures between rising and falling field temperature. Our analysis provides an impetus to minimize site-specific laboratory studies of temperature avoidance for individual species and provides an objective method for literature data comparisons.