Redear Sunfish Research Articles

Chondrichthyes and Osteichthyes from the early Pleistocene Leisey Shell Pit local fauna, Hillsborough County, Florida

The early Pleistocene (early Irvingtonian) Leisey Shell Pit ichthyofauna was recovered from two large commercial shell pits located less than 1 kilometer inland from Tampa Bay in Hillsborough County, Florida. The combined fish fauna from the two Leisey sites is composed of 73 species, including 23 species of sharks and rays and 50 species of bony fish. This is the largest fish fauna ever reported from the Cenozoic of Florida, and includes 34 taxa that represent new additions to the fossil record of the state. There are four extinct taxa in the fauna, all ofwhich are Chondrichthyes: the mako shark Isurus hastalis, the nurse shark Ginglymostoma serra, the snaggletooth shark Hemipristis serra, and the guitarfish Rhynchobatus sp. The genera Hemipristis and Rhynchobatus are now restricted to the Indo-West Pacific region. The two sites comprising the Leisey Shell Pit Local Fauna, Leisey 1A and Leisey 3A, have somewhat different faunas. The most common fish from Leisey 1A in decreasing order of abundance are: alligator gar Atractosteus spatula; snook Centropomus sp.; mullet Mugil sp.; bull shark Carcharhinus leucas; and eagle ray Myliobatis sp. These species, as well as the majority of the remaining fauna, suggest a shallow marine or estuarine environment such as a coastal bay or mouth of a large river. In contrast, the Leisey 3A ichthyofauna is dominated by the freshwater sunfish family Centrarchidae, in particular, redear sunfish Lepomis microlophus, largemouth bass Micropterus salmoides, and redbreast sunfish L. auritus. Other common fish from Leisey 3A are found in freshwater habitats as well, including: Mugil sp.; freshwater catfish of the family Ictaluridae; bowfin Amia calva; lake chubsucker Erimyzon sucetta; killifish Fundulus seminolis, golden shiner Notemigonus crysoleucas, and pickerel Esox sp. The fish fauna from Leisey 3A is indicative of a low gradient freshwater habitat such as a large stream or river, probably well inland from its mouth. With only a few exceptions, the faunas from both Leisey sites are typical of modern Florida Gulf Coast fish communities. The Leisey ichthyofauna bears witness to the stability of Florida's aquatic environments on a paleontological time scale, and offers a baseline from which to view the rapidly changing community structure of to days coastal habitats.

Preference of Redear Sunfish on Zebra Mussels and Rams-Horn Snails

ABSTRACT We tested prey preferences of adult (200- to 222-mm long) redear sunfish (Lepomis microlophus) on two size classes of zebra mussels (Dreissena polymorpha) and two-ridge rams-horns (Helisoma anceps) in experimental aquaria. We also tested physical limitations on consuming these mollusks and determined prey bioenergetic profitability. Redear sunfish strongly preferred rams-horns over zebra mussels, but they displayed no size preference for either prey. Ingestion was not physically limited since both prey species up to 15-mm long fit within the pharyngeal gapes of redear sunfish. Rams-horns were more bioenergetically profitable than zebra mussels and ingestion of rams-horn shell fragments was about three times less than zebra mussels. Rams-horns were somewhat more resistant to shell-crushing, but all size ranges of both prey species tested were crushable by redear sunfish. These studies suggested that the redear sunfish should not be considered a panacea for biological control of zebra mussels.

Chromium accumulation in three species of Central Florida Centrarchids

Stormwater ponds are required in Central Florida when land is developed to treat the resulting stormwater. The St. Johns River Water Management District, the agency that regulates stormwater discharges in Central Florida, frequently approves plans that create habitat for fish and wildlife by planting desirable wetland and aquatic vegetation in the littoral zones of stormwater ponds to compensate for the loss of wetlands. The various species of fish that inhabit stormwater ponds serve as a food source to wildlife, especially wading birds. The objective of this study was to determine if fish that live in stormwater treatment ponds in Orlando, Florida contained significant concentrations of chromium. In order to determine if there were differences in chromium concentrations in fish with different foraging strategies, three species of sunfish (Centrarchidae) with substantially different foraging strategies were selected for this study: largemouth bass (Micropterus salmoides), a predator; redear sunfish (Lepomis microlophus), a bottom feeder; and bluegill sunfish (Lepomis macrochirus), an omnivore. Many researchers have shown that large quantities of chromium are found in urban runoff. Chromium sources are largely associates with the operation of motor vehicles. Several investigators have determined that chromium from urban runoff concentrates in the sediment of stormwater ponds. Sedimentsmore » represent the most concentrated physical pool of metals in aquatic environments, and they are ingested by many types of aquatic organisms. Most fish are capable of accumulating heavy metals from their diet and from water through their gills. 17 refs., 1 fig., 3 tabs.« less

Concentrations of heavy metals associated with urban runoff in fish living in stormwater treatment ponds

Redear sunfish (Lepomis microlophus), largemouth bass (Micropterus salmoides), and bluegill sunfish (Lepomis macrochirus) were collected from stormwater ponds and natural lakes and ponds (controls) in Orlando, Florida and analyzed for cadmium, nickel, copper, lead, and zinc in order to determine: (1) if fish that live in stormwater treatment ponds contained significant heavy metal concentrations and (2) if there were differences in heavy metal concentrations between species with different foraging strategies. Redear sunfish from stormwater ponds contained significantly higher (p<0.005) concentrations of cadmium, nickel, copper, lead, and zinc than redear from controls. Largemouth bass collected from stormwater ponds contained significantly higher (p<0.005) concentrations of cadmium and zinc than those from control sites. Bluegill from stormwater ponds contained significant copper concentrations (p<0.005) as compared to bluegill from control sites.

Evaluation of aquaculture effluents

Water quality data were collected from six Department of Fisheries and Aquatic Sciences (FAS) aquaculture ponds at the University of Florida and two ponds at each of four private farms. Effluents from four of the FAS channel catfish ( Ictalurus punctatus) ponds were treated by pumping the water into a retention pond or vegetated ditch. At the stocking rates used, little relationship existed between harvest densities (kg·ha −1) and water quality parameters; however, harvest densities were lower than in most intensive production systems. Total suspended solids (TSS) were elevated by seining; however, if pumping did not occur immediately after seining, the TSS settled prior to pumping. Passing water through a retention pond or vegetated ditch reduced TSS. Mean water quality parameters in channel catfish fingerling ponds and sportfish (largemouth bass, Micropterus salmoides; bluegill, Lepomis macrochirus; redear sunfish, L. microlophus) fingerling ponds were generally lower than in the food-size channel catfish ponds except for dissolved oxygen. This study was conducted to develop a water quality database from a variety of soil types and cultured species. These data along with data from one catfish farm located in Northwest Florida were evaluated to determine if effluents from these farms meet Florida water quality standards. Using these data, the Florida Department of Environmental Regulation (FDER) developed a general permit for fish farms. Sufficient data from ornamental fish farms were available, and therefore ornamental fish farms were included in the permit without additional data collection.

How Well Can Fishes Prey on Zebra Mussels in Eastern North America?

Literature on mollusk-eating fishes was reviewed to determine the potential for different species of fish to control zebra mussels in eastern North America. At least six species are potential predators of zebra mussels because they possess (1) both upper and lower pharyngeal teeth or (2) lower pharyngeal teeth and chewing pads located on the dorsal roof for crushing mollusk shells. Freshwater drum (Aplodinotus grunniens) and two centrarchids, redear sunfish (Lepomis microlophus) and pumpkinseed (L. gibbosus), possess both upper and lower pharyngeal teeth and are likely to consume more zebra mussels than fishes with only lower pharyngeal teeth. Only two catostomid species, copper and river redhorses (Moxostoma hubbsi and M. carinatum), have chewing pads that enable them to crush mollusks. The exotic omnivorous common carp (Cyprinus carpio), possessing lower teeth and a chewing pad, may prey on zebra mussels when aquatic insect larvae, its preferred food, become rare. Managing populations of drum, sunfishes and redhorses to reduce exploitation of large individuals and improve their habitats are suggested as means to intensify biological control of zebra mussels in eastern North America. Other Eurasian molluscivores, the roach (Rutilus rutilus) and the black carp (Mylopharyngodon piceus) should not be introduced into North America because research has shown repeatedly that an introduced biological controller usually does not forage for unwanted pests or reside only in preferred habitats of pests. Drum, sunfishes and redhorses should be preferred over these exotics as biological controllers of zebra mussels in North America because these native fishes will likely occupy newly established habitats of zebra mussels.

Behavior of sunfish exposed to herbicides: A field study

AbstractAn underwater closed‐circuit video system was used to remotely monitor and record the behavior of bluegills (Lepomis macrochirus) and redear sunfish (Lepomis microlophus) guarding their nests before, during, and after applications of aquatic herbicides. Nests were sprayed to achieve a nominal concentration of 4 mg/L of either a dipotassium salt of endothall (Aquathol‐KD̊), a dimethylamine salt of 2,4‐dichlorophenoxyacetic acid (2,4‐D), or water (control). No significant differences in rates of nest abandonment existed among the three treatments (p &gt; 0.10). Abandonment averaged 5.17 min for both species and herbicide treatments, whereas the herbicides persisted in the water column for at least 45 min. When abandonment occurred, congeners nearly always intruded on the nest to feed on eggs or fry. After spraying, the adjusted mean frequency of rim circling, fanning, and agonistic behaviors exhibited by bluegills guarding eggs did not differ among the three treatments (p ⩾ 0.35). These results suggest the two herbicides will not elicit pronounced shifts in reproductive behavior of sunfish when they are properly applied.

Variability of Electrofishing Crew Efficiency, and Sampling Requirements for Estimating Reliable Catch Rates

Abstract Comparisons of electrofishing catch rates were conducted on two lakes in central Florida; sampling precision was examined in five other lakes. Significant differences were found among crews for various sizes (adults, subadults, quality) of largemouth bass Micropterus salmoides, bluegill Lepoinis inacrochirus, and redear sunfish L. microlophus. Results were not consistent between lakes, and rankings of crew catches varied among size categories. The number of samples required to estimate largemouth bass catch per minute with confidence limits that are within 10% of the mean at the 80% confidence level ranged from 4 to 110 (median, 19), based on catch rates from seven central Florida lakes. From 2 to 28 samples (median, 5) would be required to estimate largemouth bass catch per unit effort within 20% of the mean. For bluegill, the number of samples required to yield confidence limits within 20% of the mean ranged from 4 to 83 (median, 17). Precision ofwithin 20% ofthe mean is recommended for fisheri...

Indirect effects of fish on macrophytes in Bays Mountain Lake: evidence for a littoral trophic cascade.

We began this experiment to test specific hypotheses regarding direct and indirect effects of fish predation on the littoral macroinvertebrate community of Bays Mountain Lake, Tennessee. We used 24 m2 enclosures in which we manipulated the presence and absence of large redear sunfish (Lepomis microlophus>150 mm SL), and small sunfish (L. macrochirus and L. microlophus <50 mm SL) over a 16-mo period. Here we report on effects of fish predation on gastropod grazers that appear to cascade to periphyton and macrophytes.Both large redear sunfish and small sunfish maintained low snail biomass, but snails in fish-free controls increased significantly during the first 2-mo of the experiment. By late summer of the first year of the experiment, the difference in biomass between enclosures with and without fish had increased dramatically (>10×). Midway through the second summer of the experiment, we noted apparent differences in the abundance of periphyton between enclosures containing fish and those that did not. We also noted differences in the macrophyte distribution among enclosures. To document these responses, we estimated periphyton cover, biovolume and cell size frequencies as well as macrophyte distributions among enclosures at the end of the experiment. When fish were absent, periphyton percent cover was significantly reduced compared to when fish were present. Periphyton cell-size distributions in enclosures without fish were skewed toward small cells (only 12% were greater than 200 m3), which is consistent with intense snail grazing. The macrophyte Najas flexilis had more than 60 x higher biomass in the fish-free enclosures than in enclosures containing fish; Potamogeton diversifolius was found only in fish-free enclosures. These results suggest a chain of strong interactions (i.e. from fish to snails to periphyton to macrophytes) that may be important in lake littoral systems. This contrasts sharply with earlier predictions based on cascading trophic interactions that propose that fish predation on snails would enhance macrophyte biomass.

Differential length-weight relations among centrarchids (Pisces: Centrarchidae) from tidal freshwater and oligohaline wetland habitats

Use of tidal-freshwater and oligohaline wetlands by centrarchid fishes along a coastal river-estuarine gradient is partially controlled by salinity. I examined length-weight relationships between tidal-freshwater and oligohaline populations ofMicropterus salmoides, M. punctulatus, Lepomis microlophus, L. punctatus andL. macrochirus, species that commonly use saline wetlands. Analysis of covariance (ANCOVA) documented significantly heavier specimens ofMicropterus salmoides andLepomis microlophus in tidal-freshwater (P 0.05) in length-weight patterns. Specimens ofL. macrochirus andM. punctulatus were heavier at a given length in tidal-freshwater than oligohaline marshes, but direct comparisons were not possible because of violation of the parallel slope assumption of ANCOVA. Data on some species examined contradict previous laboratory physiological data which suggested that salinity and its rate of change control use of saline habitats by centrarchids. These data support the hypothesis that use of habitat is a multidimension function of abiotic and biotic factors and that laboratory physiological studies based on abiotic factors alone may not provide all the answers to questions centered around life-history consequences of using various habitats.

Fish-Mediated Alternative Life-History Strategies in the Dragonfly Epitheca cynosura

We investigated the potential impact of predation on life-history traits of aquatic insects by examining various factors affecting the voltinism pattern of Epitheca (Tetragoneuria) cynosura (Say) in Bays Mountain Lake, Sullivan County, Tennessee, USA. We observed the growth of individual Epitheca protected from competition and predation in small (0.03 m 2 ) in situ enclosures. Approximately 70% of the larvae followed univoltine development; this contrasts sharply with earlier studies in Bays Mountain Lake where only 25% of emerging imagoes were thought to be univoltine. We also conducted a study of the diets of large sunfish to identify the predator with the greatest potential impact on Epitheca population densities. Redear sunfish (Lepomis microlophus) consumed large numbers of Epitheca during mid-July, and the dragonflies consumed were larger than expected based on size-distributions found in the lake. In fact, those eaten were often from sizes identified as potentially following univoltine dev...

Selenium accumulation, reproductive status, and histopathological changes in environmentally exposed redear sunfish.

Comparisons were made of the accumulation of selenium, histopathological damage, and reproductive status of redear sunfish (Lepomis microlophus) collected in July 1986 from Martin Lake (a contaminated site) and Lake Tyler (a reference site). Hepatic concentrations of selenium were four times higher in Martin Lake sunfish (7.6 +/- 0.5 ppm) than in fish from the reference lake (2.1 +/- 0.2 ppm). Redears collected from the contaminated lake had lower condition factors than individuals collected from the reference site. Sunfish with elevated levels of hepatic selenium had substantial alterations in the liver including necrosis, cytoplasmic vacuolation, and Kupffer cell proliferation. The ovaries of mature fish collected from Martin Lake frequently had atretic follicles, abnormally shaped follicles, connective tissue hypertrophy, asynchronous oocyte development, and an overall reduction in the number of developing oocytes. These histopathological changes in the ovaries of Martin Lake sunfish were not accompanied by alterations in gonadal steroid titers in the blood. No histopathological lesions could be detected in the testes of Martin Lake fish. Most of the males collected from the contaminated site were immature and had lower circulating levels of sex steroid hormones than reference males. The results show that tissue burdens of selenium have declined by 25% since this sunfish population was sampled last in 1981. Further, the results of this study indicate that the overall health and reproductive status of selenium-contaminated fish collected from Martin Lake is still seriously impaired.

The Channel Catfish Fishery at Pony Express Lake, Missouri, 1963-1984

Abstract Pony Express Lake in Missouri was initially stocked in 1964 with fingerling largemouth bass Micropterus salmoides, bluegills Lepomis macrochirus, redear sunfish Lepomis microlophus, and 5-8-in channel catfish Ictalurus punctatus. The lake was opened to fishing in January 1966. Since the opening, annual supplemental stockings of 8-10-in channel catfish have been made at rates of 13-50 fish/acre. No negative effects on other species were documented that could be related to channel catfish stocking. The size distribution of channel catfish in gill-net catches, all years combined, corresponded to the size composition of angler catches except for fish less than 12.0 in. Experimental gill nets (1/2-2-in meshes) were most effective for sampling the smaller fish in the population. Channel catfish averaged 15.4 in at age 4 after completing two growing seasons in the lake. Annual daytime fishing pressure averaged 396 h/acre from 1966 through 1984, 33% of which was directed at channel catfish. Mean total an...

Influence of Hydrilla on Harvestable Sport-Fish Populations, Angler Use, and Angler Expenditures at Orange Lake, Florida

Abstract An infestation of hydrilla Hydrilla verticillata caused an 85% reduction in angler effort at Orange Lake, Florida, in 1977 when plant coverage exceeded 80% of the lake. Nonlocal anglers were only 3% of the total number of anglers fishing the lake in 1977, but were 37% of the anglers during 1978 and 1979, when hydrilla coverage was less than 19%. Although angler use of Orange Lake was greatly reduced during the peak 1977 hydrilla infestation, the number of fish caught per hour during 1977 was equivalent to or greater than that of all other study years for all species of sport fish. The almost complete plant coverage did not lower the population of harvestable largemouth bass Micropterus salmoides or black crappie Pomoxis nigromaculatus. Numbers of harvestable bluegill Lepomis macrochirus and redear sunfish Lepomis microlophus were, however, negatively correlated with hydrilla coverage. Reduction in angling caused a 90% loss in revenue from the Orange Lake sport fishery that is valued at approximat...

Abundance, Spatiotemporal Distribution, and Growth of Bluegill and Redear Sunfish Fry in a 0.6-ha Pond

ABSTRACT The temporal spawning distributions and certain aspects of the early life-histories of bluegill (Lepomis macrochirus) and redear sunfish (L. microlophus) were compared in a recently stocked 0.6-ha pond in central illinois. Redear sunfish spawned earlier, at lower temperatures, and for a shorter interval than did bluegill. Age-0 redear sunfish were primarily restricted to littoral habitats; in contrast, age-0 bluegill occupied both limnetic and littoral habitats, but they became increasingly restricted to littoral habitats as their size increased. First-summer growth rates of early-spawned individuals of the two species were similar, but late-spawned redear sunfish grew significantly slower than similarly-aged bluegill. However, because redear sunfish spawned earlier, in September their young were generally larger ([Xbar]TL = 39.0 mm) than bluegill young ([Xbar]TL = 25.8 mm). Age-0 bluegill were much more abundant than age-0 redear sunfish in September (57 to 1). Inconsistent reproductive success is implicated as a factor limiting recruitment in redear sunfish populations.

Effect of Commercial Harvest of Sport Fish on the Black Crappie Population in Lake Okeechobee, Florida

Commercial harvest of black crappie (Pomoxis nigromaculatus), bluegill (Lepomis macrochirus), and redear sunfish (Lepomis microlophus) was conducted in Lake Okeechobee, Florida during 1976-1981. This fishery removed an annual average of 56 and 24% of the estimated standing crop of harvestable-size black crappie and sunfish (bluegill and redear sunfish combined), respectively. Including the sport harvest, the annual exploitation of black crappie was estimated at 65%. This high exploitation rate resulted in significant increases in growth rate and condition factor of black crappie. The results suggested that the commercial harvest of sunfish also improved the growth rate of young black crappie. Fluctuations in the quality of the black crappie sport fishing were related primarily to hydrologic factors, and the population did not show signs of overfishing. Revenue generated by this commercial fishery exceeded $27 million.

Enzyme activities and growth rates in two sunfish species and their hybrids

Intra- and interspecific crosses involving green sunfish (Lepomis cyanellus) and redear sunfish (L. microlophus) were made to produce progeny of each parental species and reciprocal hybrids. The differences in growth rates of different progeny classes were determined and related to their differences in tissue enzyme activities. After one growing season, redear ♀ × green ♂ hybrids showed the greatest growth (average weight gain) followed by that of green ♀ × redear ♂ hybrids, redear and green sunfish. At the end of the second growing season, green ♀ × redear ♂hybrids had the highest average weight followed by redear ♀ × green ♂ hybrid, redear and green sunfish. Specific activities of different enzymes (malate dehydrogenase, lactate dehydrogenase, glucosephosphate isomerase and phosphoglucomutase) in one or more tissues (skeletal muscle, liver, and eye) also differed among the progeny classes. No significant correlation was observed between growth and the tissue levels of enzyme locus expression. Enzyme activity levels of hybrids tended to be intermediate to those of parental species, whereas growth rates of each hybrid exceeded parental growth rates. Apparently, alterations of gene regulation in the hybrids are exerting different effects upon these morphological and molecular traits.

Taxonomy and Biology of Phagicola nana (Digenea: Heterophyidae)

Phagicola nana is resurrected from synonymy and redescribed based on syntypes from the arctic fox, Alopex lagopus, and adults from an experimental infection in the Virginia opossum, Didelphis virginiana. Natural definitive hosts include the great blue heron, Ardea herodias; least bittern, Ixobrychus exilis; and possibly gannet, Morus bassanus. The Virginia opossum, northern raccoon, laboratory white mouse, Syrian hamster, and domestic chicken serve as experimental definitive hosts. Natural metacercarial infections by P. nana occurred in the largemouth bass (Micropterus salmoides), redear sunfish (Lepomis microlophus), bluegill (L. macrochirus), and orangespotted sunfish (L. humilis) collected in estuarine bayous and rivers of Mississippi, Florida, and Georgia. Metacercariae caused minor histopathological alterations in fish hosts by inducing formation of fibrotic host capsules. They encysted primarily in sites already containing fibroblasts. Phagicola nana may have broad host specificity for piscivorous birds and mammals inhabiting estuarine marshes. Moreover, humans probably may become infected with P. nana by ingesting raw or inadequately prepared centrarchid fishes. Phagicola nana (Ransom, 1920) was originally described from a single specimen of the arctic fox, Alopex lagopus (Linnaeus) (as Vulpes 1.). Cause of the fox's death in 1906 at the National Zoological Park, Washington, D.C., was diagnosed as intense purulent peritonitis and septic metritis. At necropsy, Dr. H. W. Graybill collected specimens of it and P. longa (Ransom, 1920), and Ransom (1920) described them both. Because the fox was born and lived its entire four years at the Park, we assume it acquired both heterophyids from raw fishes fed to it. Metacercariae of P. longa parasitize mullets (Edwards & Overstreet, 1976; Hutton, 1957; Hutton & Sogandares-Bernal, 1958, 1959, 1960; Skinner, 1975), and adults occur at least in Procyon lotor (Linnaeus) and birds along the Atlantic and Gulf of Mexico coasts (Harkema & Miller, 1962, 1964; Hutton & Sogandares-Bernal, 1960; Overstreet, 1978). This paper is the first to report metacercariae of P. nana, a species that we consider distinct from P. angrense (Travassos, 1916). We found metacercariae of P. nana commonly We thank Sybil Hamlet, Historian, National Zoological Park, Smithsonian Institution, Washington, D.C., for providing information concerning the type-host of Phagicola nana and John C. Pearson, University of Queensland, for commenting on the manuscript. Also, Dr. J. Ralph Lichtenfels loaned us type and voucher specimens of heterophyids from the USNM Helminthological Collection; Dr. Jeffrey M. Lotz and Mr. Larry Shults donated heterophyids collected from birds and mammals in Ocean Springs, Mississippi; Dr. Adrian Lawler provided laboratory-reared chickens and collected raccoons and opossums for us; and Ronnie Palmer, Joan Durfee, and John Lamb provided technical assistance. We acknowledge the University of Wisconsin-Eau Claire for providing a Faculty Improvement Grant to WFF. The study was conducted in cooperation with the U.S. Department of Commerce, NOAA, National Marine Fisheries Service, under PL 88-309 Project Nos. 2-382-R and 2-393-R. 2 Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54701,

Differences in tissue expressions of enzyme activities in interspecific sunfish (Centrarchidae) hybrids and their backcross progeny.

The extent of naturally occurring variations of enzyme locus expression was determined for three tissues (liver, muscle, and eye) in two species of sunfish (Centrarchidae), the green sunfish (Lepomis cyanellus) and the redear sunfish (L. microlophus). The genetic basis for species differences in tissue enzyme specific activities of malate dehydrogenase (EC 1.1.1.37), lactate dehydrogenase (EC 1.1.1.27), phosphoglucomutase (EC 2.7.5.1), and glucosephosphate isomerase (EC 5.3.1.9) was investigated by determining enzyme specific activities in the tissues of the reciprocal F1 hybrids and of their backcross progenies. The specific activities for most enzymes in hybrids were intermediate between those of the parental species. Significant differences in enzyme specific activity were detected among the F1 progeny as well as those of backcrosses. Variations in specific activity levels in one tissue were often independent of variations in specific activities in a different tissue. However, the changes in the specific activities of different enzymes within the same tissue were often positively correlated. The tissue glucosephosphate isomerase activity differences appear not to be due to different functional contributions of the glucosephosphate isomerase allelic isozymes. Cluster analysis of distributions of specific activities revealed no simple Mendelian pattern of inheritance for control of tissue enzyme activity. Our results suggest a polygenic control of tissue enzyme specific activity levels.

LINKAGE RELATIONSHIPS OF NINE ENZYME LOCI IN SUNFISHES (LEPOMIS; CENTRARCHIDAE)

Linkage relationships of nine enzyme loci; aconitase (Acon ), esterase (Est), glucosephosphate isomerase A and B ( Gpi), glycerate-2-dehydrogenase (G2dh), malic enzyme (Me ), phosphoglycerate kinase (Pgk), phosphoglucomutase (Pgm ) and superoxide dismutase (Sod), were investigated in sunfishes (Lepomis, Centrarchidae). Reciprocal F(1) hybrids produced from crosses between green sunfish (Lepomis cyanellus) and redear sunfish ( L. microlophus) were backcrossed with each of the two parental species. A three-point linkage map comprising G2dh, Pgk and Sod is reported. The frequencies of recombination between G2dh and Pgk and between Pgk and Sod are estimated as 45.3 and 24.7%. The remaining six loci assort independently. Possible linkage conservation and homology of this linkage group with those of other vertebrate species are discussed.