Journal of the Southeastern Association of Fish and Wildlife Agencies

The digestibility of nutrients in six semi-purified rations containing variable levels of protein, cellulose and starch by channel catfish in troughs was evaluated by using chromium oxide as an inert reference in the feeds. Excreta were collected using an indirect trough collection method and a direct intestinal collection method. Digestibility coefficients determined on excreta collected in troughs were higher than coefficients determined from excreta collected from the intestine. There was no significant difference in protein Or fat digestibility from the six rations when the trough collection of excreta method was used. In the intestinal collection method, excreta were collected, separately, from four areas of the digestive tract, namely, the stomach, upper intestine, lower intestine and rectum. The absorption of protein in twoyear old channel catfish occurred the length of the intestine up to and possibly including the rectum.

A number of studies have been done on the tolerance of fish to salt, but there is little information on the effect of salt on growth of fish. In the present study, repeated trials in tanks indicated that selected concentrations of salt have a significant effect on the growth of channel catfish. Subsequent trials in ponds showed a similar effect. The increased growth resulting from selected concentrations of salt is of such magnitude as to be of practical significance in some situations. An explanation for this effect is postulated.

This paper includes a discussion of a catfish polyculture experiment conducted in brackish water ponds at the Rockefeller Wildlife Refuge, Grand Chenier, Louisiana. Ponds containing channel catfish (1ctaluTUs punctatus) only served as controls and were compared to other ponds containing various stocking ratios of blue (1. furcatus) , channel and white catfish (I. catus) to determine if production could be increased. Length-weight relationships, coefficients of condition, food conversions, survival and growth data were compared in an analysis of the various stocking combinations. These data supported by that of past studies demonstrated that channel catfish grown under monoculture conditions exhibited the best survival, food conversion, coefficient of condition and growth. It is also stressed that we believe the culture of mixed species to be nearing practicality and may be a future requirement in order to realize additional profits from fish farming operations.

Vitamin fortification of the Auburn No.2 pelleted fish feed increased net production of channel catfish an average of 19.3 percent in feeding tests conducted in replicated earthen ponds between April 13 and November 9, 1970. A stocking density of 4,000 fingerlings acre was used and the fish were fed 6 days per week. In comparison to a second commercial catfish feed containing identical v\\tamin fortification the fortified Auburn No.2 feed produced an increase in net production of 39.5 percent. Feed conversion, gain per day and average weight of fish at harvest were all superior with the fortified Auburn No.2 feed when compared to the other two rations.

Channel catfish virus disease is caused by a specific virus which has been isolated from 23 epizootics reported from nine different states. This paper gives clinical signs, mortality patterns and susceptibility of different age and size fish to channel catfish virus. Recommended practices for controlling the disease are presented.

"Red-sore" disease of fishes caused by the stalked ciliate Epistylis, is very common and widespread in the Southeastern U. S. Epizootics occur most frequently during the winter and spring months. Research has shown that this species is not an obligate parasite but only uses the host fish as an attachment site. The disc-like attachment organelle, penetrating the skin of the fish, apparently secretes an enzyme that dissolves the fishes' scales or spines and produces pit-like inflamed lesions. Bacterial infections often occur secondarily to the Epistylis infestation. Observations of the life history have shown a formation of telotrochs which are characteristic of the order Peritricha. Preliminary laboratory tests show that a single treatment with potassium permanganate at a rate of 2 ppm or formalin at a rate of 15 ppm will control Epistylis.

This is the first report of Goezia sp. from freshwater fish in North America. Extensive mortalities among striped bass (Morone saxatilis) resulted from the damage caused by these nematodes. A possible mode of infection is given and a discussion of the pathology associated with the worms is presented.

The use of fluorescent labelled antibody (FA) systems provide a means for detecting both the presence of the agent, Aeromonas liquefaciens and fish antibodies to that agent. Bacteria from experimentally infected fish could be identified within 6 hours after obtaining the sample by the FA technique. The preparation of specific antiserum to A. liquefaciens and a proposed method for rapid detection of the bacterium from field specimens is presented.

Various stocking rates were tested over a three year period for production of striped bass in culture ponds. Rates ranged from 10,000 to 160,000 fry per acre. Results indicate higher rates produced as high a percent yield as lower rates. Four food types were also tested during this period to determine which produced the best yields. Commercially prepared supplemental feeds did increase production over natural foods. Food habits data support earlier information that Copepoda, Cladocera and Insecta are important food organisms to juvenile striped bass.

The investigation to verify striped bass, Morone saxatilis (Walbaum), reproduction in Keystone Reservoir utilized egg sampling and shoreline seining methods. Conditions in the Arkansas River throughout the egg sampling period were unfavorable and seemed to indicate little chance for a successful spawn. However, on June 21, 1971, natural reproduction was verified. The total 1971 fingerling survival was calculated at 975,000. Ten mature females and four male striped bass were taken below Keystone dam by electrofishing during the period May 24 to June 3, 1971. These fish were transported 150 miles to hatchery facilities where artificial spawning was conducted. One seven-pound female was successfully spawned and fry were produced. Problems, procedures and resulting recommendations are discussed. Age and growth determinations and length-weight relationsips are presented.

Stomach content analyses were performed on 213 striped bass (11.480.0 mm TL) collected from culture ponds at the Front Royal Fish Cultural Station, Virginia, during the 1969 and 1970 rearing seasons. Cladocerans (families Sididae, Daphnidae and Bosminidae) constituted the major portion of the diet of these fish with copepods (family Cyclopidae) and insects (family Chironomidae) also being important food organisms. Cladoceran abundance in the stomachs increased after the bass were 30-40 mm long, while copepod abundance decreased and insect abundance remained relatively stable. The fish negatively selected Brachionidae (rotifers) and copepod nauplii. Daphnidae and Bosminidae were positively selected and Cyclopidae was eaten in relation to its abundance in the ponds. Sididae was positively selected when present in small numbers, but eaten in proportion to its abundance when present in large numbers.

The ovaries of 28 mature female hybrids, striped bass Morone saxatilis (Walbaum) X white bass Morone chrysops (Rafinesque) from Lakes Hartwell and Clark Hill were utilized in determining fecundity in this oviparous species. These data were collected from all year classes present that were sexually mature, which included year classes I, II, and III. No females of year class 0 were captured during these studies. Many hybrid males one year of age were caught at the spawning grounds and specimens as small as 269 mm in total length appeared to be sexually mature. Female hybrids as small as 409 mm in total length and some weighing as little as 917 grams were found to be sexually mature. Mean ova production although increasing in direct proportion to age, total length and body weight remained rather constant as to average number of eggs per pound of body weight.

Research on the extensive culture of striped bass, Morone saxatilis (Walbaum), was conducted in ponds at Auburn University Fisheries Research Unit in the spring of 1971. Investigations were conducted to determine the effect of water hardness, source of fry: and immediate versus delayed stocking on the survival of striped bass fry. Twelve 0.10-acre earthen ponds were used. Six ponds were treated with calcium sulfate to raise the hardness to 150 ppm. The hardness of the remaining ponds was approximately 20 ppm. Striped bass fry from two sources (Cooper River, South Carolina, and Savannah River, Georgia) were stocked immediately after receIvmg them from the hatchery or after they began feeding. Stocking rates varied from 60,000/A to 210,000/A. There was no difference in survival between sources of fry.

Fishes belonging to the Notropis cornutus complex are commonly encountered by hydrobiologists. Consequently, a reasonable taxonomic designation of these forms is important. Several attempts have been made to place these fishes in an acceptable classification. To clarify the status of their classification, specimens sampled from collections totaling more than 3400 fish from 40 counties in Kentucky were analyzed for dorsal stripe configuration, chin pigmentation, and anterior dorsolateral and circumferential scale counts. Distribution and meristics of shiner populations presented in this and other studies suggest that the cornutus-chrysocephalus complex forms a cline extending from the Gulf coast northward to the Great Lakes region. There is a general pattern of increasing scale counts of circumferential and anterior dorsolateral scales from south to north.

Redbreast sunfish Lepomis auritus (Linnaeus) were found to spawn during June at water temperatures of 71° to 78°F. Redbreast sunfish redds were almost identical in design and size in the Lumber, Waccamaw, and the South Rivers. Each redd was located in or near a sheltered area such as a log, fallen tree, or stump. The preferred bottom substrate for spawning was sand and small gravel. No redds were observed in silt or detritus. Age II, III, IV, V, and VI year redbreast sunfish had mean egg counts of 963, 1,000, 3,563, 5,620, and 8,250, respectively, with corresponding standard deviations of 88.4, 435.9, 763.1, 851.9, and 278.4. The most important food items found in the redbreast sunfish stomachs were aquatic insects, represented by Coleoptera, Odonata, and Ephemeroptera. It appeared that redbreast sunfish were selective and preferred the larger mayfly, dragonfly, and beetle larvae found in the streams.

This paper summarizes the final report on the investigation of theRoanoke bass in North Carolina. It contains new data on recognitioncharacters, distribution, food studies, sexual maturity, and age-andgrowthstudies which essentially augments the report "A PreliminaryReport on the Biology of the Roanoke Bass, Ambloplites cavifrons Cope,in North Carolina," Smith, 1969, presented in the 23rd SoutheasternProceedings, 1969.

In the spring of 1970 and 1971, vegetation transects were run on22,700 acre Lake Tohopekaliga in Osceola County, Florida. The objectiveof this study was to monitor the response of various plant types to a7 foot drawdown and compare results with those from a study done in1956. As a result of dewatering, littoral vegetation advanced lakewara,expanding from an area of approximately 9,000 acres to 10,500 acres, a16% increase. The significance of this plant response, relative to standingcrop of fish and invertebrate fish-food organisms, is discussed. Five of 16 dominant plant types occurred most frequently or hadwidest distribution during a high water period (1970). The remaining11 occurred most frequently or had widest distribution during low waterperiods (1956 and 1971). In the 1956 study it was assumed that water stage duration determinedthe distribution of annual and perennial plants.

Effects of crowding were investigated with respect to growth, feeding, food conversion, mortality, and health of bullfrogs (Rana catesbeiana) up to 9 months of age. No statistically significant differences were found with regard to growth, food consumption, food conversion, mortality, or health. The average food conversion (C) was less than 2.6 during the first two months of growth and values between 1.65 and 1.99 were obtained. By the third month most values approached 3.00. A high correlation was found between gain and food conversion. Daily consumption as high as 350/0 was recorded. The fastest growing bullfrogs approached or exceeded 226 g (lh lb.) in 8 months from metamorphosis. Analysis of 68 frogs for sexual maturity showed that males had motile sperm by 4 months of age and a weight of 32 g. Analysis of females indicated eggs approaching maturity may be produced as early as 6 months from metamorphosis.

A brief review on the history of bullfrog (Rana catesbeiana) culture is covered. Present research programs in frog culture are reviewed. The need for developing culture techniques are paramount due to the demand for bullfrogs in biological and medical research, education and dwindling of native stocks. Bullfrogs are reared in 20-foot diameter concrete tanks, housed indoors with controlled temperature. Up to 5,000 young frogs placed in each tank are thinned to about 1,000 as they grow. Crickets, worms, fish, and tadpoles are used for food. Research needs include the development of a commercial feed, genetically defined strains, simple and effective breeding techniques, methods for disease control, and modification of rearing tanks for more efficient cleaning and temperature control.

A continuous-flow respirometer was constructed to measure the effect of pesticides and related pollutants on oxygen consumption of estuarine fishes. The parts of the respirometer in contact with pollutants were constructed of glass and teflon for efficiency in cleaning. Filtered, irradiated sea water of constant temperature and salinity was gravity-fed through ten experimental and ten control respiration chambers in which individual fish were held. Flow rates through the chambers were controlled by stopcocks and measured by flowmeters; dissolved oxygen was determined by the Winkler method before and after water passed through each chamber. Pollutants were metered into the experimental chambers by syringe pump.

Ultrasonic transmitters were commercially purchased. They were cylindrical in shape, 90 mm long by 19 mm in diameter, and they weighed 29.5 g, with battery, in water. They transmitted at a frequency of 74 kilocycles/second. The number of days of active transmission was related to battery type and impulse rate. Transmitters emitting a greater number of impulses per second, with a range of 2.4 to 5.8, tended to stop transmitting sooner than those emitting fewer impulses per second. The difference in longevity between a 3 and 6 impulse per second transmitter was estimated to be 14 days. The average transmitting life of 11 transmitters was 30.5 days, with a range from 24 to 52 days. Battery capacity was a significant factor affecting longevity; transmitters with a 160 milliamperehour battery had an average longevity of only 18.5 days. None of the tags had a transmitting life equal to the 60 days advertised by the manufacturer.

Benthic samples were sorted by three methods: electrical stimulus applied to living organisms, preserved in rose bengal formalin solution, and preserved natural-colored. The rose bengal stained samples were picked most accurately and rapidly except in very low invertebrate concentrations where the electrical stimulus was more efficient. Naturalcolored samples had the least accurate retrieval and were picked at a rate intermediate to the other two methods.

Bold's Basal and Gorham's media were used to culture algae removed from the digestive tracts of Blue Tilapia, Tilapia aurea (Steindachner). Nine fish representing three-size categories collected from Lake Parker, Florida, were used in the study. Samples extracted from three areas of the gut were introduced to the culture media within twenty-four hours after collection. Microscopic examination of the cultured materials was conducted over a four-week period to enable the completion of reproductive cycles and excystment of algal cells. Twenty-one taxa of algae were identified by sampling the culture vessels. Planktonic green algae were the dominant foods of tilapia at the time of sampling. Species of Scenedesmus, Pediastrum, A.nkistrodesmus and chlorococcoid algae appeared in all specimens. Colonial chlorophytes, pennate diatoms, flagellated unicells, and remains of filamentous algae occurred less frequently. Spirulina sp.