Rock Bass Research Articles

Mechanism of Biomagnification in Fish under Laboratory and Field Conditions

While biomagnification of certain organic contaminants in food chains has been observed in field studies, the mechanism of the biomagnification process is still unresolved. Knowledge of the mechanism by which contaminants are absorbed and biomagnified in food chains is important in environmental risk assessment and studies of chemical bioavailability. In this study, we hypothesize a fugacity based model of the gastrointestinal absorption of contaminants. We test the model in a 73 day laboratory, gastrointestinal magnification study of 2,2‘,4,4‘,6,6‘-hexachlorobiphenyl in adult rainbow trout (Oncorhynchus mykiss) and in a field study of the gastrointestinal magnification of PCB congeners in rock bass (Ambloplites rupestris). Both studies show that the fugacity of the test chemicals in the gastrointestinal tract (GIT) can increase to levels up to 7−8-fold greater than those in the consumed food. The fugacity increase in the GIT is the result of a drop in the chyme's fugacity capacity for the test chemicals ...

Indirect Effects of Fishery Exploitation and Pest Control in a Riverine Food Web

Abstract We used an energy-based food web model to evaluate indirect effects of fishery exploitation and aquatic insect pest control on food web structure and recreational fisheries in the New River, West Virginia. Key groups represented in the model were aquatic insects, age-1 and age-2 crayfish (Cambaridae), age-1 and age-2 larvae of the dobsonfly Corydalus cornutus (hellgrammites), prey fishes, and age-0 to adult smallmouth bass Micropterus dolomieu, rock bass Ambloplites rupestris, and flathead catfish Pylodictis olivaris. We focused on exploitation of crayfish and adult smallmouth bass because of their strong prey–predator interaction and their importance as fishery resources. We first simulated a range of harvest rates for adult smallmouth bass, while keeping crayfish harvest rate at its field-estimated value. Outcomes suggested that adult smallmouth bass were being harvested near the maximum sustainable yield (MSY), and that more restrictive harvest regulations would not necessarily increase produc...

Is there always an influence of shoal size on predator hunting success?

Theoretical and empirical studies predict that there should be a decrease in hunting success of predators with increasing prey group size. Most of these studies investigated situations in which predator and prey were in full view of each other before, during and after an attack. In this study, single rock bass Ambloplites rupestris were given an opportunity to launch surprise attacks at shoals of creek chub Semotilus atromaculatus that ranged in size from two to 13 fish. There was no significant influence of either shoal size or attack distance on predator success rate and no significant relationship between attack distance and shoal size. Furthermore, it was found that the leading fish of a shoal was attacked significantly more often than fish in other shoal positions, indicating that predation risk was not shared equally among shoal members. Also, leading fish in larger shoals (eight to 13 fish) were not more likely to survive a predator attack than ones in small shoals (two to seven fish).The consequences of these results are discussed in the general context of antipredator benefits of grouping.

Is there always an influence of shoal size on predator hunting success?

Theoretical and empirical studies predict that there should be a decrease in hunting success of predators with increasing prey group size. Most of these studies investigated situations in which predator and prey were in full view of each other before, during and after an attack. In this study, single rock bass Ambloplites rupestris were given an opportunity to launch surprise attacks at shoals of creek chub Semotilus atromaculatus that ranged in size from two to 13 fish. There was no significant influence of either shoal size or attack distance on predator success rate and no significant relationship between attack distance and shoal size. Furthermore, it was found that the leading fish of a shoal was attacked significantly more often than fish in other shoal positions, indicating that predation risk was not shared equally among shoal members. Also, leading fish in larger shoals (eight to 13 fish) were not more likely to survive a predator attack than ones in small shoals (two to seven fish).The consequences of these results are discussed in the general context of antipredator benefits of grouping.

Distribution of littoral fishes in structurally complex macrophytes

By considering patchiness in the littoral vegetation, we were able to distinguish within-lake distributions among species and between young-of-the-year and yearling-and-older fishes. We characterized the macrophytes in Lake Mendota, Wisconsin, along transects using rake grabs to estimate species diversity and sonar charts to estimate the patchiness at 1-m intervals. We discerned two distinct littoral fish assemblages, one characterized by rock bass (Ambloplites rupestris) and smallmouth bass (Micropterus dolomieu) in unvegetated areas and another by a diverse assemblage in vegetated areas. Patchiness of macrophytes, not simply abundance, determined variations in the specific structure of the fish assemblage: e.g., yellow perch (Perca flavescens) were more dominant and abundant where vegetation was species rich and structurally complex as well as abundant. Young-of-the-year and yearling-and-older fishes differed in their distribution patterns: e.g., age 0 bluegill (Lepomis macrochirus) were more abundant where Eurasian watermilfoil was abundant and patchy and yearling-and-older bluegill where vegetation was more dense and species rich. Furthermore, yearling-and-older black bullhead (Ameiurus melas) and brown bullhead (Ameiurus nebulosus) were more common in patchy macrophyte beds than in species-rich vegetation. The largest catches of age 0 white bass (Morone chrysops) occurred at sites with sandy shallow beaches and patchy milfoil beds farther offshore. These patterns were discerned because we assessed macrophyte structural complexity at multiple scales and we separated young-of-the-year from older fishes.

Distribution of Tissue Kallikreins in Lower Vertebrates: Potential Physiological Roles for Fish Kallikreins

Fish skeletal muscle prokallikrein was purified from black sea bass, Centropristis striata, and used for the production of polyclonal antiserum. Tissue proteins from primitive fish and teleosts, an alligator, and an insectivore were resolved by sodium dodecylsulfate-polyacrylamide gel electrophoresis, Western blotted, and probed with fish muscle prokallikrein antiserum. A recurring theme was the presence of approximately 36 and 72 kDa kallikrein-like proteins in skeletal muscle, heart, gill, kidney, and spleen of higher teleosts and in selected tissues of sturgeon, shark, alligator, and mole. The presence of immunoreactive kallikreins in osmoregulatory organs such as the gills of teleosts and the rectal gland of sharks signifies a potential role for these proteins in osmoregulation. Black sea bass, rock bass, and sturgeon contained many immunoreactive kallikreins in their swimbladders, which implicates a role for kallikreins in the regulation of blood flow and vascular permeability to facilitate gas exchange within the bladder. Kallikreins were consistently identified in skeletal muscle and heart of all the species evaluated and may regulate local blood flow, muscle contraction or relaxation, or participate in various transport processes. The antiserum to fish prokallikrein recognized immunoreactive kallikreins from pancreatic tissues from fish and lower vertebrates, but not from the pyloric caecum of sea bass. The wide distribution of tissue kallikrein in lower vetebrates suggests that it may participate in a variety of physiological functions.

Autumn use of woody snags by fishes in backwater and channel border habitats of a large river

Snags are important to fish communities in small rivers and streams, but their importance to fishes in large rivers has not been investigated. This study examined snag use by fishes during autumn in backwater and channel border habitats in the upper Mississippi River, and compared these to fish communities in reference sites without snags. Species assemblages differed significantly between backwater and channel border habitats, and between snag and reference sites within the channel border, likely responding to differences in substrate, depth, and current velocity. In both habitats, average fish biomass and abundance were higher (2 to 50 ×) at snag sites than at reference sites, but these differences were significant only for channel border biomass. Fish taxa richness differed between backwater and channel border habitats, but not between snag and reference sites. Most large piscivorous fishes (e.g., Micropterus spp., Stizostedion spp.), several insectivorous fishes (Lepomis macrochirus, Ambloplites rupestris, Minytrema melanops), and a few prey fishes (L. macrochirus, Notropis atherinoides) were significantly more abundant at snag sites than at reference sites, suggesting active selection of snags for foraging or protection. Snag quality, as assessed by a snag rating index, had a direct effect on attracting fish communities with greater biomass, especially within the channel border habitat. These results indicate that snags are important habitat for fish communities in both backwaters and channel border habitats of the upper Mississippi River.

Indirect effects of lake acidification on Chaoborus population dynamics: the role of food limitation and predation

A twofold increase in Chaoborus punctipennis abundance following experimental acidification of one basin of Little Rock Lake, Wisconsin, provided an opportunity to examine the hypotheses that C. punctipennis dynamics were regulated by (i) food resources for instars I and II, (ii) fish predation on instars III and IV, and (iii) invertebrate predation on instars I and II. Neither food limitation nor fish predation appeared to be important constraints on C. punctipennis abundance. Although rotifer biomass increased significantly during the acidification, C. punctipennis did not respond in a consistent manner to variation in food availability. Bioenergetics estimates of C. punctipennis consumption by rock bass (Ambloplites rupestris), the most acid-sensitive fish species, were small compared with C. punctipennis production. In contrast, invertebrate predation appeared to be an important constraint on C. punctipennis abundance. Chaoborus punctipennis abundance increased dramatically when abundance of the predator Mesocyclops edax declined to near zero. Comparison of M. edax predation rates and first instar production suggested that M. edax could exert strong predation pressure on C. punctipennis Thus, invertebrate predation may create a juvenile bottleneck for populations of small-bodied Chaoborus species in moderately productive acidified lakes.

Evidence of Secondary Consumption of Invertebrate Prey by Double-Crested Cormorants

-The piscivorous nature of the Double-crested Cormorant (Phalacrocorax auritus) is well documented. However, many researchers who have used regurgitated pellets to describe the diet of cormorants report that invertebrates compose a small but consistent portion of the diet. We examined the hypothesis that invertebrates found in pellets are primarily the result of secondary consumption. We used odds ratio analysis to examine associations in 2,846 individual pellets between the presence of specific invertebrate prey and the presence of fish species known to consume those invertebrate taxa. Significant (P < 0.05) relationships occurred between gastropods and pumpkinseed (Lepomis gibbosus) and ictalurids, and between decapods and rock bass (Ambloplites rupestris) and smallmouth bass (Micropterus dolomieu). Significant (P < 0.05) relationships were also found between pelecypods and pumpkinseed and ictalurids. We suggest that the invertebrate prey we observed in pellets were present in the digestive tracts of fish that were consumed by Double-crested Cormorants and hence represent secondary consumption by cormorants. We conclude that consumption of invertebrates by Double-crested Cormorants may be overestimated in the literature in instances where the diet was described using pellets. Received 7July 1997, accepted 23 August 1997, final version received 15 September 1997.

Mortality Risk of Spatial Positions in Animal Groups: the Danger of Being in the Front

Abstract We modified Hamilton's (1971) selfish herd model by introducing directional movement to the prey groups and the predators. The consequences of this modification with regards to differential predation risks are compared to Hamilton's original model (using stationary prey groups) and tested against empirical data. In model 1, we replicated Hamilton's original predator-prey system. In models 2 and 3, prey groups were mobile and predators were mobile (model 2) or stationary (model 3). Our results indicate that additional to the positive risk gradient from centre to periphery predicted by Hamilton's model for stationary groups, there might be another positive risk gradient from the rear to the front part in moving groups. Furthermore, models 2 and 3 suggest that moving groups should generally exhibit an elongated shape (longer than wide along the axis of locomotion) if risk minimisation is the only factor concerned. Also smaller inter-individual distances are predicted for front individuals than individuals elsewhere in the group. Empirical data based on the three-dimensional structure of fish shoals (using roach, Rutilus rutilus) were consistent with the above two predictions. A second experiment which involved lake chub, Semotilus atromaculatus, as prey and rock bass, Ambloplites rupestris, as predators, provided direct support for the hypothesis that individuals in front positions of groups incurred a significantly higher predation risk than fish in rear positions. Finally, we discuss the differential risks of different group positions in the context of potential foraging gains which provides the basis for a dynamic model of position preferences in group-living animals.

Fish Species in Chicago Harbors of Lake Michigan, 1988 to 1990, as Determined by Electrofishing and Creel Surveys

ABSTRACT We surveyed the fish species in five Chicago harbors of Lake Michigan from the spring of 1988 until the end of June of 1990 to establish a baseline of information regarding this fishery. The study took place prior to the invasion of the zebra mussel and exotic fish species such as the round goby and the ruffe, which have subsequently altered the habitat. Twenty-six fish species were captured by electrofishing. These species included five species which were not known to occur in Illinois waters of Lake Michigan; they were: white perch, quillback carpsucker, longear sunfish, black crappie, and the freshwater drum. Seventeen species were caught by sport fishermen. One of these species, the channel catfish, was never previously caught by fishermen or other sampling techniques in the Illinois waters of Lake Michigan. The abundant species were alewife, carp, gizzard shad, golden shiner, and yellow perch. Other species included largemouth bass, smallmouth bass, rock bass, bluegill, pumpkinseed, green sunfish, black bullhead, and white sucker. Chinook salmon, coho salmon, brown trout, rainbow trout, and a single lake trout were caught during the fall months. Yellow perch was the primary sport fish caught, and rainbow smelt was caught by gillnets in spring.

Nontroglobitic Fishes in Caves: Their Abnormalities, Ecological Classification and Importance

-A total of 190 individuals representing 14 fish species were discovered from surveys of four West Virginia caves. Cottus carolinae ssp. and Lepomis macrochirus were c a p tured in Buckeye Creek Cave, while Semotilus atromaculatus, L. cyanellus, Oncorhynchus mykiss, Rhinichthys atratulus and Ambloplites rupestris were collected from Bruffey-Hills Creek Cave. Seven species were captured in Piercys Cave, including two species, Notropisphotogenis and N. uolucellus, never before recorded from caves. Six species, Cottus bairdi, Catostomus commersoni, Saluelinus fontinalis, A. rupestris, R atratulus and S. atromaculatuswere captured in Piercys Mill Cave. Many of the S. atromaculatus were depigmented upon initial inspection; however, exposure to light often returned normal coloration. Nontroglobitic fishes inhabiting caves are known to exhibit abnormalities such as depigmentation, skeletal deformities or reduced eye size. Little attention has been given to documenting occurrences of nontroglobitic fishes in caves, and most occurrences have been considered accidental. Correct classification of many populations is difficult since categories in the current system do not accommodate them adequately. Some fish occurrences may more accurately fit the trogloxene category, although, each case must be examined independently. The possible effects of cavernicolous, nontroglobitic fishes on other cavedwelling organisms, especially endangered troglobites, rarely has been considered and should be studied.

The role of trophic bottlenecks in stunting: a field test of an allocation model of growth and reproduction in yellow perch, Perca flavescens

Stunting in freshwater fish populations may be due to low availability of one or more prey components within their diet. If the limiting prey constitute a trophic level (i.e. zooplankton, benthos, or fish), we define the phenomenon as a trophic bottleneck. Growth of a non-stunted population of yellow perch, Perca flavescens, was simulated using an allocation model based on reported ontogenetic shifts in diet (planktivory to benthivory to piscivory). The model was then perturbed by limiting the available ration individually for each of the three feeding types. The resulting simulated growth curves all reflected lower growth rates than the unperturbed state and the shape of the curve differed between the limited food types. Only the reduced benthic ration produced a simulated growth that matched that observed for the stunted yellow perch of Lac Hertel (Quebec). To test the hypothesis that benthic ration was limiting growth in Lac Hertel, all the fish species in the lake were sampled for diet composition and total length at age. We predicted that species feeding upon benthic invertebrates should exhibit the slow growth characteristic of stunting (based on the results of the allocation model). Of the seven fish species found in Lac Hertel, four were stunted: yellow perch, pumpkinseed, Lepomis gibbosus, rock bass, Ambloplites rupestris, and brown bullhead, Ictalurus nebulosus. Three species were non-stunted: northern pike, Esox lucius, golden shiner, Notemigonus crysoleucas, and white sucker, Catostomus commersoni. All stunted species fed on benthic invertebrates and all non-stunted species, except the white sucker, did not feed upon benthos. The prediction of the allocation model was thus supported.

Do Rock Bass (Ambloplites rupestris) Induce Microhabitat Shifts in Mottled Sculpin (Cottus bairdi)?

In Coweeta Creek, North Carolina, mottled sculpin (Cottus bairdi) co-occurred seasonally with a potential predator, rock bass (Ambloplites rupestris). We conducted experiments to determine whether rock bass affected microhabitat use by sculpin in an artificial stream. The general behavior and microhabitat use of both species in the artificial stream resembled those observed in Coweeta Creek. When all microhabitat observations were pooled, there was little evidence of predator-induced shifts by sculpin. However, at night in trials without predators, sculpin generally occurred farther from shelter, over greater amounts of gravel and lower quantities of erosional substrata. When we added predators, however, this response was obviated. Nonetheless, the lack of strong responses by sculpin to rock bass, coupled with their co-occurrence only during seasons of low metabolic activity, lead us to suspect that rock bass do not produce strong shifts in microhabitat use by most sculpin in the Coweeta drainage.

Relationships between Environmental Variables and Size-Specific Growth Rates of Illinois Stream Fishes

We quantified size-specific growth of small and large rock bass Ambloplites rupestris, bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, and channel catfish Ictalurus punctatus from Illinois streams. Growth rates for each species fell within ranges previously reported for lakes and rivers in Illinois and adjacent states, although growth rates in our study averaged slightly lower. Intraspecific growth rate comparisons of small and large individuals were not significantly correlated for bluegill and rock bass. This suggests ontogenetic shifts occurred in diet or habitat use of these two species, similar to those reported for lentic populations. Using 12 biological, 22 physical, and 8 chemical variables collected concurrently with the fish, we developed simple- and multiple-regression models of growth for each species and size. Our best multiple-regression models accounted for 67–99% of the growth variation in seven species–size combinations, with substrate variables contributing to models for all species except rock bass. Although these models require testing against independent data for general applicability, they demonstrate the potential for predicting the growth of stream fish from commonly collected, and often readily available, habitat data. These empirical relationships with environmental variables may also enhance the efficiency of stream fisheries management by providing an inexpensive, a priori basis for directing management efforts.

Climate response among growth increments of fish and trees.

Significant correlations were found among the annual growth increments of stream fish, trees, and climate variables in the Ozark region of the United States. The variation in annual growth increments of rock bass (Ambloplites rupestris) from the Jacks Fork River was significantly correlated over 22 years with the ring width of four tree species: white oak (Quercus alba), post oak (Quercus stellata), shortleaf pine (Pinus echinata) and eastern red cedar (Juniperus virginiana). Rock bass growth and tree growth were both significantly correlated with July rainfall and stream discharge. Variations in annual growth of smallmouth bass (Micropterus dolomieu) from four streams were significantly correlated over 29 years (1939-1968) with mean May maximum air temperature but not with tree growth. The magnitude and significance of correlations among growth increments from fish and trees imply that conditions such as topography, stream gradient, organism age, and the distribution of a population relative to its geographic range can influence the climatic response of an organism. The timing and intensity of climatic variables may produce different responses among closely related species.

Seasonal variation in heat shock proteins (hsp 70) in stream fish under natural conditions

1. 1.|Fish ( Pimephales promelas, Salmo trutta, Ictalurus natalis and Ambloplites rupestris) respond to seasonal changes in their environment by synthesizing heat shock proteins with a molecular weight of approximately 70 Kd (hsc/hsp-70). 2. 2.|Lowest levels of hsc/hsp-70 measured with ELISA occurred in winter, followed by a high level in spring, a significant decrease in summer and another in fall. 3. 3.|Caution must be applied in developing heat shock proteins as biomarkers so that their presence in organisms under “normal” conditions is not misinterpreted as an indication that the organisms are stressed.

The roles of predation, competition, and exploitation in the trophic dynamics of a warmwater stream: a model synthesis, analysis, and application

We developed a trophic dynamic model of key populations and processes in the New River, West Virginia, to identify the mechanisms most responsible for maintaining food web structure. Key populations were represented by thirteen model components and were aquatic insects; age-1 and age-2 crayfish (three species); age-1 and age-2 hellgrammites (Corydalus cornutus larvae); non-game fishes; age-0, age-1, and adult smallmouth bass (Micropterus dolomieu); age-0, age-1, and adult rock bass (Ambloplites rupestris); and age-0, age-1 to age-3, and adult flathead catfish (Pylodictis olivaris). In this system, crayfish and hellgrammites are harvested to provide bait for the recreational fishery that extensively exploits the three predatory fish species. Predation and intraspecific regulation were represented with nonlinear algorithms, and linear terms represented fishery harvests. Interspecific competition among components occurred through predation on shared prey. Error analysis of the model suggested that predation was the most important mechanism in maintaining system structure (the disposition of biomass among system components). Further, the trophic relation between each component and its prey accounted for 34–64% of the variability in food web structure, whereas predation on each component explained 1–24% of food web structure variability. Therefore, so-called ‘bottom-up’ effects were more influential than ‘top-down’ effects. Interspecific competition and intraspecific regulation had secondary roles in maintaining New River food web structure, although intraspecific regulation was most important to aquatic insects, which were not predatory in our model. Both forms of competition are probably tempered by extensive predation and exploitation in the New River system. Exploitation was a secondary structuring agent to adult smallmouth bass, which experience a high rate of harvest in the New River.

Hydrostatic stability of fish with swim bladders: not all fish are unstable

The center of mass and the center of buoyancy were found to occur at the same relative longitudinal location along the body of the elongate-bodied European eel (Anguilla anguilla), the fusiform yellow perch (Perca flavescens), and two gibbose species, rock bass (Ambloplites rupestris) and bluegill (Lepomis macrochirus). The locations of these centers were not affected by fish size. Therefore the fish were neutral in hydrostatic pitching equilibrium. The vertical location of the centers of mass and buoyancy were the same for bluegill, but the center of mass was dorsal to the center of buoyancy in yellow perch. The observations on bluegill show that neutral hydrostatic rolling equilibrium is possible. Our conclusions on similarity or separation between the locations of the centers of mass and buoyancy derive from tests of significance and differ from conclusions reported elsewhere on the basis of mean values only. In general, fish with swim bladders can be at or close to neutral hydrostatic equilibrium but any disturbance will be destabilizing. This probably explains continuous fin-beating of fish in apparently still water.

Comparative morphology of the myomeres and axial skeleton in four genera of centrarchid fishes.

We used X-rays and dissection of myotomes to quantify the axial morphology of four species of centrarchid fishes (Micropterus salmoides, Ambloplites rupestris, Pomoxis nigromaculatus, and Lepomis macrochirus). Proceeding from dorsal to ventral, we designated the two epaxial and two hypaxial protions of the myomeres AB, BC, CD, and DE, respectively. For each of 11 myomeres, spaced at 10% increments along the length of the fish, a total of 14 variables described the length and orientation of each portion, the dorsalventral symmetry, and the overall height and longitudinal span of the entire myomere. Nine variables described the lengths, orientation, and symmetry of the vertebral centra, neural and hemal spines, and ribs. Analysis of variance revealed that, with one exception, all 23 morphological variables varied significantly both among species and among longitudinal locations within a species. However, the extent of longitudinal and interspecific variance differed considerably among different variables. Maximal myomeric height ranged from about 45% of the standard length (SL) in Lepomis to 27% SL in Micropterus. Longitudinal and interspecific increases in overall height of the trunk myomeres resulted primarily from greater lengths of CD. Compared to other portions of the myomere, the length of BC was most conservative both longitudinally and interspecifically. Dorsal-ventral symmetry of the myomeres and axial skeleton was greater in the caudal region than in the trunk in all species, and the myomeric morphology diverged least among species in the posterior caudal region. The overall longitudinal span of superficial myomeric landmarks varied from 6% to 18% SL, and, including the deep portions of the myomeres, the longitudinal span varied from about 7 to 10 vertebrae. Within each of the species, myomeric and skeletal variables were often not significantly correlated, but for the pooled data of all species there were usually highly significant correlations between myomeric and skeletal morphology. For example, strong correlations existed between BC and the underlying neural spines, and between CD and the underlying ribs and hemal spines. In contrast, the longitudinal spans of entire myomeres and underlying axial skeletal segments were only weakly associated. © 1994 Wiley-Liss, Inc.