Journal of the Southeastern Association of Fish and Wildlife Agencies

Depth distributi.on of tarpon (Megalops atlantica), pinfish (Lagodon rhomboides), Atlantic Croaker (Micropogon undulatus), black drum (Pogonias cromis), and striped mullet (Mugil cephalus) placed in cylindrical cages extending from the surface to the bottom of the thermal effluent of a steam-electric power plant was monitored daily using a depth locator. Temperature,conductivity, pH, dissolved oxygen, turbidity, and gas saturation levels were recorded immediately after recording the depth distribution data. Overall trends suggested that intraspecific interaction had an effect on fish distribution. Pinfish, black drum, and Atlantic croaker reacted to ambient light levels. Mean depth of pinfish, black drum, and striped mullet was shown to be significantly correlated with %-total gas saturation. Tarpon and black drum responded to temperature, croaker responded to conductivity, and striped mullet responded to %oxygen saturation.

Water quality and aquatic fauna associated with ditching systems dug in 1968 and in 1972 in an irregularly flooded marsh were studied. Salinity, pH, temperature, dissolved oxygen, were determined monthly. Dissolved oxygen was lowest at the upper ends of the ditches. Organic matter seemed to have been built up at the upper ends ofthe ditches due to inadequate tidal flushing. Mats of submersed vegetation hindered tidal flow which reduced the flushing effectiveness of the tides. Water quality differences between the upper and lower portions of the ditches seemed to be physical rather titan biological. Organisms collected were typical estuarine species. There were no significant benefits from the ditches other than to control mosquitoes.

The influence of floating tire breakwaters on the ecology of coves was studied in Lake Carl Blackwell, a 1400-ha reservoir in north-central Oklahoma. Breakwaters, consisting of a single row of 18-tire modules, were installed across the mouths of 2 coves (8.5 and 9.8 ha). Wind, wave height, water temperature, transparency, suspended solids, turbidity, and sedimentation rate were measured during one 7-month period at windward and leeward sites in 2 experimental and 2 control coves. Populations of fish and benthic invertebrates were monitored in experimental and control coves for 2 years after construction of the breakwaters. At leeward sites, breakwaters reduced wave heights by 50%, increased transparency in both experimental coves and increased sedimentation rate in I cove. Slight differences in turbidity, suspended solids, and temperature between windward and leeward sides of the breakwaters were similar to differences between lakeward and shoreward areas of control coves.

Chain pickerel (Esox niger) in Lake Conway consumed progressively more fish with increase in size. A shift also occurred in size, species composition, and relative abundance of fish prey with chain pickerel size. An index of selection was applied to food habit data. There was an increase in number of species and an increase in size of species that were positively selected as chain pickerel size increased. Size, rather than abundance of forage fish was the dominant influence on prey selection.

The removal of a 381 mm minimum size limit on walleye in Glenville Reservoir, North Carolina did not significantly affect the mean calculated total length ofthose fishes at the first 3 annuli. However, a significant increase in calculated total length was determined at the fourth annulus. There were no significant changes in the mean calculated growth increments. Comparisons of net survey data collected before and after removal of the minimum size limit showed no change in the average catch of walleye per net-day. Also, there was no significant change in the mean total length and the mean age of walleye caught by anglers. The increased exploitation afforded by removal of the minimum size limit had no effect on the annual harvest of walleye and had a positive effect on the growth of older walleye.

Fish populations in the Neuse River, North Carolina, were studied near a steam electric plant which included a low-head dam as part of the installation. The purpose of the study was to describe the fish population of a moderate-sized upper coastal plain river, and to provide insight in to the distribution of fishes relative to the dam. Fish were collected by gill netting, fyke netting, electrofishing, seining, and trawling to examine the various species and sizes of fishes present. Sampling was conducted over a I-year period to include seasonal changes in the fish population. Fifty-two species offish were collected including several estuarine forms, although the study area was located at approximately river mile 140. Several species of anadromous fishes were collected, but of these, only American shad were abundant.

Eight species of bacteria, 8 genera of parasites, and I species of virus were found infecting rainbow trout (Salrno gairdnen), brown trout (S. trutta), brook trout (Salvelinus jontinalis) and yellow perch (Perca jlavescens) from 2 locations in the Chattahoochee River below Buford Dam. There were no clinical signs ofdiseases caused by these potentially pathogenic organisms. Microscopic lesions were present in some of the fish, and the gill was the organ most often affected. These lesions were probably caused by a chemical in the water, but it was not possible to identify the chemical with the results of this study. There were fewer lesions in the fish collected at the downstream station compared to the fish collected near the dam, possibly a result of higher dissolved oxygen concentrations downstream.

Three natural lakes were studies to determine effects of grass carp (Ctenopharyngodon idella Val.) introduction on invertebrates. Benthic macroinvertebrate populations were changed after the introduction of grass carp changed the existing habitat in the 3 natural lakes. Species diversity (d), number of taxa and pollution-intolerant organisms decreased in all lakes after grass carp introduction. Macrophytes were also reduced in all study areas and several native species were eliminated. Changes in benthos corresponded to changes in water quality and aquatic vegetation.

Nutritional and physical properties of the diet, management, and environment affect voluntary food consumption by channel catfish (lctalurus punctatus). Laboratory studies in which channel catfish were fed twice daily to satiation with semipurified diets containing various ratios of protein and digestihle. energy indicated that food intake was directly proportional to calorie density in the diet but independent of protein density until the protein percentage exceeded 45. Protein levels above 45% caused reduced food intake. Pond experiments in which channel catfish were fed to satiation twice daily, once daily, or on alternate days demonstrated that fish fed twice daily consumed the most food when water temperature was 26 C or greater, those fed once daily consumed the most food at 20-26 C, and those fed on alternate days consumed the most food when temperature declined below 20 C.

From 20 May to 28 October 1978, 5 experimental fish ponds at Arkansas State University Fish Farm, Walcott, Arkansas, were utilized in determining the effects of cropping on channel catfish growth. Three ponds were used as experimental ponds and 2 as controls. Selected physiocochemical properties of the water were measured. With the exception of air and water temperatures, properties of the experimental ponds fluctuated more than the controls due to indirect effects of cropping. However, all values fell within acceptable ranges for channel catfish (Ictalurus punctatus Rafinesque) culture. Mean biweekly gains for the experimental and control fish were .065 and 0.63 kg respectively. Analysis of variance and t-test analysis indicated that at an innitial stocking density of 3720 fish per ha, cropping yielded no significant differences in growth rate or weight gain.

Three experimental ponds were stocked with a polyculture of channel catfish (Ictalurus punctatus). silver carp (Hypopthalmichthyes molit rix) , and bighead carp (Aristichthes nobilis). Three control ponds were stocked with catfish alone. In 2 of the 3 sets of ponds, there was little difference in catfish production (less than I and 10% by weight) while total production in the polyculture ponds far exceeded the controls with catfish alone. In the remaining set. catfish production was less in the polyculture pond but total production remained higher as a result of the additional growth of the silver and bighead carp. Lesser objectives were to refine artificial spawning methods and describe the difference in water quality resulting from the presence of the filter feeding Chinese carps. Successful hormone induced spawning techniques were developed and an improvement in pond water quality was noted.

Data were obtained on dissolved oxygen (DO) problems in 36 ponds used for the commercial production of channel catfish (lctalurus punctatus) in Tallahatchie County, Mississippi. The frequency of DO concentrations below 2 mg/Iiter at dawn was greatest during summer when water temperatures were above 26C. On summer days, 20% or more of the ponds often had DO concentrations below 2 mgjliter at dawn. During the I54-day period, I May through I October, emergency aeration was employed a total of 410 times in the 36 ponds. During the summer, at least 1 pond was aerated most nights, and a maximum of 9 ponds was aerated on a single night. Findings suggest that at least I aeration unit should be available for each 4 ponds.

Ammonia is the primary nitrogen-containing waste product of fish. Under natural conditions, ammonia is converted first to nitrite and then to nitrate. Ammonia and nitrite are toxic to fish at low levels, but nitrate is relatively non-toxic. Ammonia has a variety of toxic effects, including reduced growth rates, whereas nitrite primarily interfers with oxygen transport. The literature pertaining to toxic levels and effects of environmental ammonia and nitrite as well as experimental methods of inhibiting these toxicities are reviewed. Prevention of elevated pH for high ammonia conditions, and the addition of sodium chloride for elevated nitrite levels are suggested as possible inhibitors of these toxicities in channel catfish production.

Two .05 ha ponds were planted with water chestnut (Eleocharis dulcis) corms in March 1978. After the waterchestnuts had sprouted the ponds were flooded in late March to an average depth of 15 em, and remained flooded until mid-October 1978. The ponds were drained and left dry until February 1979 when they were harvested. One pond had excellent production throughout, leading to an extrapolated level of 13,600 kg! ha. The other pond had good production only along the sides and in the shallow end due to high turbidity and unfavorably low soil pH. Production in the second pond was at the rate of 13,200 kg!ha. Production figures for intensive culture in China range from 17,000 to 34,500 kg! ha. The Chinese waterchestnut grows well in the southeastern United States and the necessary technology for mechanical harvesting and peeling have recently been developed.

Ultrasonic transmitters were surgically implanted into 50 sexually mature walleye Stizostedion vitreum vitreum (mean weight 1.9 kg) in Canton Reservoir during March 1977. The locations of these fish were determined bimontly from March through November 1977, as an indication of walleye concentration areas in the reservoir. Temperature, dissolved oxygen and pH profiles were also obtained bimonthly at 2 stations during this time. During the March spawning season walleye were all located near the riprap of the dam. The rest ofthe year the fish showed a preference for areas near submerged islands. There was also a tendency for the walleye to concentrate farther upstream along the perimeters of these islands as the year progressed. This apparent upstream movement by transmitter-equipped walleye may have been related to low dissolved oxygen concentrations near the bottom in the deeper portion of the reservoir during the summer months.

Effects of temperature on survival of peacock bass ( Cichla ocellaris) fingerlings were examined in the laboratory. Fish were acclimated to 25, 30 or 35 C prior to testing. The ultimate lower and upper lethal temperatures in freshwater were 15.6 and 37.9 C when the temperature change from acclimation was I C/ day. Salinity (10% 0) significantly reduced (P<0.05) the ultimate lower lethal temperature to 14.4 C. Acclimation temperature significantly affected the temperature at which peacock bass began losing equilibrium (LEso) and dying (CTMin) when fish were exposed to a I Cf h decrease. LEso's for the 35, 30 and 25 C acclimation temperatues were 18.9, 16.2 and 14.5 C, respectively. When fish were transferred abruptly from acclimation to 20,15 and 10 C, median resistance times were longer when there was less difference between acclimation and test temperatures.

the fish communities of the middle Savannah River and 2 cooling water intake canals connected to the river had equal species richness and were equally diverse. However, the relative abundance of functionally similar species groups differed between the localities. Sunfishes were more dominant in the canal communities. Suckers contribued 55% of the biomass in all 3 communities. Impingement was very low and spread over 32 species. Three species of c1upeids comprized 32% of the total number of fish impinged. The impingement of a number of species was disproportionate to their relative abundance in the intake canals

Threadfin shad (Dorosoma petenense) impingement at the Tennessee Valley Authority's Cumberland Steam-Electric Plant followed a seasonal pattern related to the abundance and length distribution of young-of-year fish. Electrofishing samples taken near the plant showed a similar pattern. The number ofimpinged fish (larger than 50 mm) decreased rapidly with increasing length due to reduction in abundance by natural mortality. Impingement mortality was found to be length dependent. Most individuals. less than 50 mm in length passed through the screens, while increasingly larger individuals were more likely to become impinged. Impinged fish less than 100 mm total length tended to be more plump than fish collected in rotenone samples, while impinged fish larger than 100 mm tended to be in poorer condition.

Seasonal abundance of larval fishes in Normandy Reservoir, Tennessee, was determined during the first 3 years (1976-1978) following impoundment. Relative abundance of major taxa collected with a 0.5 m frame net was compared with results of cove rotenone samples to measure year-class strength. Centrarchids dominated both larval and cove rotenone populations throughout the investigation. The strongest year class of crappie (Pomoxis spp.) was observed in 1976, even though greater larval abundance (5 times) was recorded in 1978. Threadfin shad (Dorosoma petenense) were stocked and subsequently spawned in 1977, but failed to survive the winter; gizzard shad (D. cepedianum) were the only clupeids collected in'1978.

The data from 3 years of ichthyoplankton sampling during the initial impoundment of Little Bear Creek Reservoir are presented. Trends of percentage composition and abundance are discussed by family and taxon. The Centrarchidae greatly outnumbered other families of fishes throughout the study, while c1upeids failed to become established. Strong year classes of Lepomis and Pomoxis were produced during the first year of impoundment. Relative failures of the second and third years are attributed to lack of spawning success in the case of Lepomis and predation in the case of Pomoxis. The ichthyoplankton data are compared to a preimpoundment adult survey and 3 years of concurrent postimpoundment rotenone surveys.

A cooperative study was conceived, organized and implemented by the Reservoir Committee and its member agencies, Southern Division, AFS. The Crooked Creek Bay (85 ha) of Barkley Reservoir was divided into various cove and open-water areas and treated with rotenone. Overall. 990 kg/ ha of fish were recovered.

Recovery rates were determined for marked fish released into 10 of 15 cove areas and 2 of 6 open water areas during the cove rotenone study at Crooked Creek Bay, an 85 ha arm of Barkley Lake, Kentucky. Fish were tagged with a F10y FD-68B dart tag and either released back into the same study area or introduced from an outside area. Of 986 fish tagged in the embayment, 89% were recaptured. Seventy-five percent of the marked fish were recovered in 9 cove areas, where marked fish were released back into the same cove section. Only 32% were recovered from a back-cove area in which marked fish were introduced from an open water area. Sixty percent were recovered outside this area, indicating a strong tendency for displaced fish to escape. Percentage escapement of marked fish from the other 9 cove areas was only 16%. Escapement increased in each cove section that was progressively farther from open water. Escapement also decreased as mean depth of coves increased.

Tire and brush fish attractors were sampled during the Barkley Lake Rotenone Study. Standing crop comparisons were made between tire and brush attractors and control areas. Channel catfish (lctalurus punctatus), bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), and white crappie (Pomoxis annularis) were effectively concentrated by both types of attractors, although brush exceeded tires in concentrating all 4 species. Fish attractors were particularly effective in concentrating harvestable-sized fish.

Available prey-predator ratios (API P) in Crooked Creek Bay indicated a deficiency of prey for predators (largemouth bass equivalents) 200 mm long (total length) or less. Analysis of samples collected after the application of rotenone to small coves led to overestimates of available prey. Application of adjustment factors to account for differences in fish distribution in coves and in open water improved AP/ P estimates based on small-cove samples. After reviewing previous food studies, we redefined crappies longer than 210 mm and catfishes longer than 390 mm as predators. Revised AP/ P calculations then indicated no shortage of prey in the Bay. Comparison of these data with those from a 1965 study in Douglas Lake, Tennessee, showed that predators in Douglas Lake were more efficient in cropping available prey.

Estimates of the number of largemouth bass (Micropterus salmoides) 153 mm and longer in Crooked Creek Bay made by mark-recapture techniques were compared with rotenone estimates. Electrofishing was used to collect bass for marking, while electrofishing and angling provided recaptures. Estimates obtained by Petersen and Schnabel methods generally were lower than rotenone estimates. Both methods estimated the number of intermediate-size bass more accurately than adult bass. Size distributions of bass captured by angling, electrofishing, and rotenone recovery showed no differences in the location of their central tendencies. All 3 sampling methods were selective for bass in the 293 to 368-mm size group. Electrofishing and rotenone also showed selectivity for 445 to 521-mm bass.