Longear Research Articles

Reproductive Isolation Between Pumpkinseed (Lepomis gibbosus) and Longear Sunfish (L. megalotis) (Centrarchidae) in the Thames River, Southwestern Ontario

In the middle branch of the Thames River, southwestern Ontario, nest construction and occupation by male pumpkinseeds (Lepomis gibbosus) began earlier and reached a peak earlier in the season than nesting by male longear sunfish (L. megalotis). Nevertheless the two species' breeding seasons broadly overlapped. All pumpkinseed nests occurred in backwater areas, where water flow is minimal, the substrate is a deep layer of detritus and mud, and aquatic plant growth is heavy. Some longear nests were in the backwaters, but most were in the main river, where water flow is variable, the substrate mainly sand and gravel, and vegetation sparse. Females of both species are nonterritorial and were found throughout the study area. Hybrid sunfish are present in the area and opportunities for interspecific breeding would seem to be greatest in backwaters, where males of both species may occupy nests close to each other. However, the only observed interbreeding was between female pumpkinseeds and male longears in the main river. Behavioral barriers to interbreeding occasionally break down under the turbulent social conditions associated with breeding in large longear colonies. Key words: sunfish, reproductive isolation, longear, pumpkinseed, habitat, season, behavior

The Fishery of a Missouri Ozark Stream, Big Piney River, and the Effects of Stocking Fingerling Smallmouth Bass

Abstract Over 92,000 marked fingerling smallmouth bass were stocked in Big Piney River, 1952-1955. An estimated 63,600 smallmouth bass were caught between 1953, when the first stocked fish entered the creel, and 1958 when no more marked fish were caught. Of that number, not more than 2,100 were stocked fish. This is a little more than 3% of all the bass caught and a little more than 2% return of stocked fish. Seventy species of fish were collected between 1951 and 1958 with electric shockers, hoopnets, and seines. Golden redhorse, rock bass, black redhorse, northern hog sucker, smallmouth bass and longear sunfish made up 80% of the total weight. The Ozark minnow, bleeding shiner, northern studfish, stoneroller, and bluntnose minnow were the most important forage species. This species composition is representative of Ozark headwater streams. Mean annual catch rates ranged from 35.2 to 134.9 kg/10 shocker hr of which 2.3 to 13.6 kg/10 shocker hr was bass. Big Piney River is subject to flash floods with cres...

Stream Movements and Population Density of the Orangebelly Darter, Etheostoma radiosum cyanorum (Osteichthyes: Percidae)

The orangebelly darter, Etheostoma radiosum cyanorum, is found only in the Blue River system of south central Oklahoma. Adult fish exhibited very little movement within the stream. It was found that few of the adults showed intra- raceway movement and none exhibited inter-raceway movement. Larval and young- of-year darters exhibited stream movement. Postlarval fish were found in the quiet water or pool areas of the stream. As the fish increased in size they moved into progressively swifter water. At approximately 25 mm total length they were found in the raceway areas of the stream, their adult habitat. Approximately 2.66 adult orangebelly darters were found for every square meter of raceway in the study area. The orangebelly darter, Etheostoma radiosum cyanorum (Moore and Rigney), is found only in the Blue River and its tributaries in south central Oklahoma. This fish is primarily associated with clear, flowing, rocky-bottomed raceways in the upper two-thirds of the river system. Many stream fishes live in very restricted areas during most, if not all, of their lifetimes. Gerking (1953) studied the concepts of home range and territory of stream fishes and found that the longear sun- fish, Lepomis megalotis, the green sunfish, L. cyanellus, and the rock bass, Ambloplites rupestris, limited their activities to rather small areas. Larimore (1952) obtained similar results for the smallmouth bass, Micropterus dolomieui, though these fish had larger ranges than did the previously mentioned species. Reed (1968) found that the rain- bow darter, Etheostoma caeruleum, the greenside darter, E. blen- nioides, the fantail darter, E. flabellare, and the banded darter, E. zonale, remained in rather confined areas of the stream. The present work was undertaken to determine the degree of movement which the orangebelly darter exhibited during the various stages of its life his-

Seasonal Movement and Home Range of the Longear Sunfish, Lepomis megalotis (Rafinesque) in Louisiana

The movements of longear sunfish, Lepomis megalotis, in the headwaters of three Louisiana streams were studied by electrofishing and mark-recapture techniques. A total of 352 fish were marked by fin-clipping and 72 recaptures were made over a 31-month period. Fifty-one recaptures (71%) were within the stream sections where they were marked (average length 42 m). This coincides well with data of other workers who estimated home ranges of 21-61 m for this species. During the warmer months (April-October) 337 fish (average T.L. of 90 mm) were taken in the marking section, but in winter (November-March) only 124 fish (average T.L. of 73 mm) were taken in the same sections. The sunfish appeared to desert their home ranges in winter.

Intraspecific Intrusions into Nests of Spawning Longear Sunfish (Pisces: Centrarchidae)

Northern longear sunfish (Lepomis megalotis peltastes Cope) breed in colonies of closely-spaced nests, each defended by a mature male. Conspecifics often intrude briefly into a nest with a spawning pair and are driven away by the resident male. This disruptive intrusion behavior is performed by neighboring territorial males, smaller non-territorial males, and females. Intrusion rate and distance of intruding territorial males are independent of the presence of eggs in the intruder's nests. The main function of nest intrusion by females is eating eggs; by males it is apparently the fertilization of eggs in another male's nest. The possible selective value of male nest intrusion behavior is discussed.

Mate selection in two species of sunfish (Lepomis gibbosus and L. megalotis peltastes)

The reactions of 20 male and 20 female pumpkinseed (Lepomis gibbosus) and longear sunfish (L. megalotis peltastes) to conspecifics and heterospecifics of the opposite sex were studied. Female pumpkinseeds showed a preference for conspecific males in the absence of visual cues; female longears showed a preference for conspecific males when both types of male could be seen. Males of both species did not discriminate between the two kinds of females in either the presence or absence of visual cues. Female choice of a conspecific spawning partner may be an important ethological isolating mechanism between these two species. A mechanism for hybridization between them is proposed.

Two New Myxosporida, Henneguya gambusi sp. n. and Myxosoma pharyngeus sp. n., in the Mosquitofish, Gambusia affinis (Baird and Girard)

Two new species of Myxosporida, Henneguya gambusi and Myxosoma pharyngeus, are reported from connective tissues of the integument and pharyngeal cavity, respectively, of the mosquitofish, Gambusia affinis. Immature and mature stages of the parasites are described and the nature of their infections are discussed. H. gambusi is monosporous or disporous while MA. pharyngeus is principally disporous but monosporous and polysporous development is also thought to occur. Both species are reported as pathogenic. During a survey of parasites of the mosquitofish, Gambusia affinis (Baird and Girard), from northcentral Oklahoma, two types of myxosporidan infections were found. These parasites are believed to be new species and both are herein described. The specific names H. gambusi and M. pharyngeus, referring to the name of the host and the location of cysts, respectively, are suggested. MATERIALS AND METHODS Three collections of fishes, including 143 mosquitofish, were obtained from Little Stillwater Creek, Payne County, Oklahoma, during September, October, and December 1969. Selected tissues of G. affinis were fixed in Schaudinn's, Kaformacet, or Zenker's fluids, embedded in paraffin, sectioned at 7 ,u, and stained by routine histological methods. The stains used were Delafield's hematoxylin, Heidenhain's iron-hematoxylin, and Mallory's aniline-blue connective tissue stain. Smears were prepared by transferring intact cysts through Schaudinn's fixative, Heidenhain's iron-hematoxylin, or Feulgen's nuclear reagents, alcohol, and clearing agent, followed by rupturing the cysts in a drop of mounting medium. Measurements of spores were made from fresh material in 0.65% NaCl and from fixed and stained spores that had been sectioned in situ or prepared as smears. Thirty-five fresh spores and 35 fixed and stained spores were measured for both H. gambusi and M. pharyngeus. One hundred ninety-four other fish, including 28 Lepomis megalotis, 45 L. cyanellus, 26 Carpiodes carpio, 23 Ictalurus natalis, 14 Cyprinus carpio, 9 Notemigonus crysoleucas, and 49 unidentified cyprinids and catostomids were colReceived for publication 30 April 1971. * Present address: Department of Biology, Lincoln Land Community College, Springfield, Illinois. t To whom reprint requests should be addressed. + Present address: TVA, Muscle Shoals, Alabama. lected and examined but none were found to contain parasites of the type herein described.

Repopulation of Experimentally Decimated Sections of Streams by Longear Sunfish, Lepomis megalotis megalotis (Rafinesque)

Abstract Repopulation by longear sunfish of stream segments decimated by electrofishing was studied in six areas on four streams in Louisiana. Lepomis m. megalotis (Rafinesque) repopulated the decimated areas to a level as great or greater (3.5 times) than the biomass of the decimation sample at four of the six areas within one year. Repopulation occurred between March and late summer and was accomplished by fish at least two years old. A principal factor allowing rapid repopulation of longear sunfish in the decimated segments may have been an apparent lack of repopulation by large predatory species.

Control of prespawning behaviour of sunfish ( Lepomis gibbosus and Lepomis megalotis) II. Environmental factors

Male longear ( Lepomis megalotis) and pumpkinseed ( L. gibbosus) sunfish showed high levels of aggression when kept in 25 °C water under both long and short photoperiod. Lower water temperatures (11 ° to 13 °C) inhibited both aggression and nesting. Long photoperiod (16 hr light : 8 hr dark) induced nesting by both species in 25 °C water but only by longears in 11 ° to 13 °C water. Short photoperiod (8 hr light : 16 hr dark) inhibited nesting in both species. Injection of human chorionic gonadotrophin induced nest digging in both species under short photoperiod in 25 °C water but not in 11 ° to 13 °C water. HCG had no obvious effect on aggression. Both species dug nests more readily in visual isolation than when in visual contact with conspecifics. Androgen secretion, as assayed by nest digging, is controlled by photoperiod. The level of aggression depends on water temperature and does not seem to be influenced by gonadotrophins or androgens.

Control of prespawning behaviour of sunfish ( Lepomis gibbosus and L. megalotis). I. Gonadal androgen

Gonadectomized male longear ( Lepomis megalotis) and pumpkinseed ( L. gibbosus) sunfish maintained high levels of aggression but failed to dig nests under conditions which induced nesting in sham-operated fish. The castrates dug nests when treated with methyl testosterone. Longears with gonads moved into shallow water more readily than did castrates and dug their nests closer together than did testosterone treated castrates. Male coloration was retained in castrates which were forced into close contact but not in castrates allowed to move freely in wading pools. Intact longears in wading pools retained their bright coloration, but were effectively crowded by the closeness of their nests. Nest digging and nest site location are controlled by gonadal androgens while aggression and coloration are unaffected by hormones in a crowded situation but are increased by androgens in an open situation possibly due to the crowding caused by nesting in close groups.

A comparison of semi-dwarf and standard height wheat varieties at two levels of water supply

Two semi-dwarf wheats, Mexico 120 and a late-flowering selection from this variety, were compared with two standard-height Australian varieties, Heron and Sunset. Each variety was grown with and without irrigation and lodging was controlled with artificial supports. Under natural rainfall, Mexico 120 yielded more than the standard-height varieties but the late-flowering selection yielded least of all. With irrigation, however, both semi-dwarf varieties showed a yield advantage. Features of the semi-dwarf wheats were shorter culms and longer ears, a larger proportion of car weight at anthesis, more grains set and a greater ratio of grain yield to post-anthesis leaf area. The significance of these and other factors is discussed in relation to wheat improvement in the Australian environment.

Three New Species of Monogenetic Trematodes from the Gills of Lepomis cyanellus Rafinesque and Lepomis megalotis Rafinesque of Texas and the Proposal of a New Genus, Macrohaptor

Two new species of Cleidodiscus (Cleidodiscus globus and C. similis spp. n.) from the gills of Lepomis cyanellus Rafinesque are described. Macrohaptor hopkinsi gen. et sp. n. is from Lepomis megalotis Rafinesque. The anchors of Macrohaptor are unlike those of other known Ancyrocephalinae in that the two pairs differ greatly in size and shape. The dorsal anchors are much larger than the ventral anchors, and the dorsal anchor bases are not divided into deep and superficial roots. Sunfishes were collected from the beds, lakes, and tributaries of the Navasota River and the Little River of east central Texas with seine, cast net, and hook and line. The branchial apparatus of each host was treated by the method of Mizelle and Klucka (1953) and the flukes recovered were mounted in Gray and Wess' medium (Gray, 1958). The average, minimum, and maximum measurements for each structure in the descriptions are given in microns, following the method of Mizelle (1962). Drawings were made with the aid of a camera lucida. Cleidodiscus globus sp. n. (Fig. 1) Description Cuticle smooth; only two well-defined eyespots, many scattered accessory pigment granules. Body length (mounted) 553 (374 to 825), maximum body width 77 (68 to 89) at mid-length. Head organs indistinct on mounted and cleared specimens. Pharynx discoidal, width 26 (23 to 32). Peduncle poorly defined; haptor subovate, length 47 (39 to 56) much less than width 94 (91 to 96). Anchors similar in shape (Fig. 1, DA, VA). Dorsal anchor width 10 (9 to 12), length 21 (20 to 24). Ventral anchor larger than dorsal, width 11 (10 to 12), length 28 (27 to 29). Bars dissimilar in size and shape (Fig. 1, DV, VB). Dorsal bar shorter than ventral, length 31 (30 to 31). Ventral bar variable in shape, length 40 (37 to 47). Hooks 14 in number, with typical ancyrocephaline distribution (Mizelle, 1938). All hooks similar in size, 14 (13 to 16), and shape (Fig. 1, H). Gonads not discernible on mounted specimens. Cirrus, although variable, always doubly recurved, long, terminating in fine point, base large, length 32 (27 to 37) (Fig. 1, C). Accessory piece solid, curved (Fig. 1, AP), base articulating with cirrus Received for publication 18 January 1967. base, length 25 (22 to 33). Vagina a long, sometimes tortuous tube, ends enlarged as in Figure 1, V. Host and locality: Lepomis cyanellus Rafinesque, Little River, Farm Road 437, Temple (Bell County) and Highway 36, Cameron (Milam County), Texas. Specimens studied: Four. Type specimens: Holotype USNM Helm. Coll. No. 61666, Beltsville, Maryland. Paratypes in J. D. Mizelle's collection, Sacramento State College, Sacramento, California.

A Behavioral Analysis of the Movement of Tagged Longear Sunfish

(1965). A Behavioral Analysis of the Movement of Tagged Longear Sunfish. The Progressive Fish-Culturist: Vol. 27, No. 4, pp. 211-215.

Occupancy of home range by longear sunfish, Lepomis m. megalotis (Rafinesque), and bluegill, Lepomis m. macrochirus Rafinesque

Summary 1. Size of home range in terms of linear feet of stream is estimated to be approximately 70 feet for the longear sunfish and approximately 125 feet for the bluegill. 2. The longer a given sunfish is at large subsequent to fin-clipping, the greater is the tendency for this fish to stray outside the limits of a restricted segment. 3. Older longear sunfish and bluegill appear to have larger home ranges than younger individuals. 4. Bluegill strays tend to move upstream. 5. Space-temporal aspects of home range must be considered concomitantly. 6. Short-term occupancy of home range by longear sunfish and bluegill is easily demonstrable; continuous occupancy for a period of several months is difficult to prove in that the number of recaptures diminishes greatly with the passage of time.

The Development of the Fish Population in a New Flood-Control Reservoir in Missouri, 1948 to 1954

Abstract Changes in the fish population in Clearwater Lake during the first 7 years after impoundment, 1948 through 1954, are described. This flood-control reservoir of 1,650 acres on Black River in the Ozark Highland of Missouri was completed by the Corps of Engineers, U. S. Army, in 1948. It is mostly shallower than 30 feet, and the water is moderately hard (M. O. alkalinity 97–106 p.p.m.) and clear (turbidity usually less than 7 p.p.m.). Fish samples were obtained by the use of nets, seines and rotenone, and from anglers' catches. Relative numbers, growth rates, and abundance in the anglers' catches are discussed for crappies, smallmouth bass, largemouth bass, bluegills, longear sunfish, rock bass, warmouth, green sunfish, redhorse suckers, gizzard shad, bullheads, channel catfish, and carp. All fish species numerically important in the population by 1954 had spawned successfully at least once by 1952, so it is assumed that the carrying capacity of Clearwater Lake for the species complex present was re...

Movement of Stream Fishes in Missouri

Abstract Eight hundred forty-six reports of tagged fish caught by anglers were analyzed to determine the movement patterns of 14 species of native warm-water stream fishes. Each species included a sedentary group which remained near the release point and a mobile group which ranged more or less freely. The species could be classified according to the relative abundance of the two groups. Rock bass, smallmouth bass, longear sunfish, spotted bass, and yellow bullhead were classified as sedentary species; carp, flathead catfish, largemouth bass, golden redhorse, and black redhorse are semi-mobile; and channel catfish, freshwater drum, and white crappie as mobile. The species varied greatly in the average number of days between tagging and recapture and in the direction of movement and distances traveled by the mobile fish. The mobile group usually was free longer than the sedentary fish but frequently the difference in time was not great. Mobile freshwater drum, golden redhorse, black redhorse, spotted bass,...

The Food Turnover of a Bluegill Population

The growth rate of populations of aquatic organisms has become a dominating topic of limnological research, constituting the production problem. The trophic-level concept of Lindeman ( 1942) cut through the maze of data on aquatic food relations and pointed out the possibility that the quantitative aspect of production could be attacked by considering the energy content of the organisms and the energy flow from one trophic level to another. Lindeman's ideas have been justifiably criticized by Ivlev (1945), but, despite certain inadequacies, remain a significant contribution. The concept of production is still undergoing an evolution and is now in the process of refinement. Macfayden (1948) has traced the development of this concept and of closely associated ideas. Clarke (1946) considerably sharpened the working definitions of production rate, standing crop, and yield; as a result, terminology is becoming more stabilized. The writer is particularly interested in fish production, feeling that investigation of this part of the aquatic ecosystem will contribute' significantly to the general problem. The intrinsic biological interest of fishes and their considerable economic value are incentives to a more complete understanding of this part of the production process. Ricker (1946) accelerated the study of fish production by reviewing past achievements in this field and by pointing out areas for profitable research. The present work on the food turnover by a fish population was stimulated by Ricker's analysis of the subject. The supply of food is one of the major, basic factors controlling the density and production of fishes. To understand more clearly the relationship between the fish population and its food supply, the efficiency of food conversion by sunfishes of various ages has been investigated in the laboratory. Experimental feeding of longear sunfish (Lepomis megalotis) and green sunfish (Lepomis cyanellus) was begun in 1950, and the results of these experiments have recently been published (Gerking 1952). The experiments have been continued, using the bluegill (Lepomis macrochirus) because it is widely distributed in