Journal of the Southeastern Association of Fish and Wildlife Agencies

Morphometric ratios of female striped bass (Marone saxatilis) X male white bass (M. chrysops) and female striped bass X male white perch (M. americana) that were best for distinguishing them from the parental species were: standard length/ body depth, head length/second anal spine length, head length/fourth dorsal spine length, standard length/fork length, fork length/total length, second anal spine length/third anal spine length and head length/upper jaw length. Ratios were generally intermediate between those of the parental species, but sometimes differed from those of either parent. Computer plots of ratios against standard length demonstrated that many changed as a function of fish length; thus care should be taken to utilize similar sized individuals when employing them for identification purposes. Plots of body measurements against standard length indicated most were linear, with the general exception of head depth, fourth dorsal spine length and the 3 anal spine lengths.

Production of striped bass (Morone saxatilis) fingerlings in eight 0.02-ha ponds aerated with continuously operated airlift pumps averaged 181,000 fish! ha. Ponds were initially fertilized with hay at either 560, 1120, or 2240 kg! ha and zooplankton blooms were maintained with hay and meat scrap fertilizers. The average daily application of organic fertilizers ranged from 32 to 82 kg! ha. Five-day-old fry were stocked at the rate of 250,000, 500,000, or I million! ha. Fry were supplementally fed a 45% protein diet 3 times per day after they were 22 days old. After 44 days in the pond the average weight and total length of the 49-day-old fingerlings were 0.5 g and 3.0 cm. Return per treatment averaged 116, 29, and 22% for the low, medium, and high stocking densities, respectively, and daily production averaged 2.1, 1.2, and 2.6 kg! ha. The airlift pumps maintained dissolved oxygen above 3 mg!1 when organic input averaged 62 kg! ha per day or less.

Striped bass (Morone saxatilis) were collected from Watts Bar Reservoir, Tennessee, in 1977 and 1978 to assess relationships between growth rates, survival, stocking density, and distribution patterns of stocked fingerlings. Survival and average sizes attained at ages I and 2 were inversely related to stocking density and directly related to size at stocking. Average lengths of age 3. and older fish were not related to stocking size, and the principal advantage of stocking large fingerlings was improved survival. Fingerlings stocked during June and July 1978 dispersed rapidly but tended to remain within the general area into which they had been introduced. During October and November 1978, electrofishing catch data indicated a preference for sandy shoreline habitats. Site-specific factors, such as the presence of preferred habitats, should be considered to enhance striped bass survival following stocking.

Spawning locations of striped bass (Morone saxatilis) were identified over a 118 km reach of the Arkansas River from the collection of 8,828 striped bass eggs during 1976-78. Although certain spawning locations remain constant from year to year others vary significantly within the 118 km stretch of river. Spawning began between 7 and 14 April when water temperature reached 15.5 to 18.5C and had a duration of 27 to 51 days. Spawning peaks occurred annually, generally within a few days from one year to the next. Water temperature, discharge, velocity, total dissolved solids, specific conductance, salinity, pH, alkalinity and dissolved oxygen were monitored, however, no relationship to egg production was found. However, salinity affected egg chorion diameters during the study. Chorion diameters of striped bass eggs in the Arkansas River (1.7 to 2.0 mm) were much smaller than previously reported for striped bass, due to high salinities arresting chorion expansion.

A creel survey was conducted on the lower Illinois River, Oklahoma, during 1977. Striped bass (Marone saxatilis) were also collected for food habit information and their relative abundance was noted. Striped bass predation on rainbow trout (Sa/rna gairdnen) occurred only at the downstream sampling site and only for the I-week period following trout stocking. Trout made up 40% of the food items of these striped bass within I week after trout stocking. The trout fishery of the lower Illinois River has declined in overall intensity since J965, particularly in the downstream reaches. However, the warm-water fishery, particularly for striped bass, has increased dramatically.

The fish population of Lake Columbia, a 36.42 ha Mississippi impoundment, was estimated by shoreline seining, mark and recapture, rotenone sampling and gill netting. The impoundment was then drained to evaluate results. Shoreline seining provided an excellent estimate of population balance. Mark and recapture oflargemouth bass (Micropterus salmoides) gave a statistically valid estimate and was the only method to which statistics could be applied. Length-frequency data of bass from rotenone samples were stable and appear useful, although large bass were underestimated. Rotenone samples gave stable balance ratios, but standing crop varied greatly. Gill nets captured all major species and provided useful data on species not adequately represented in rotenone samples.

Largemouth bass (Micropterus salmoides) were tagged on West Point Reservoir, Alabama-Georgia in 1976-1978 to estimate rates offishing. During the 3 years, several factors affecting these estimates were evaluated. Non-response by anglers who recovered non-reward tags was calculated to be 0.66; tag loss was estimated to occur at an average rate of 4% per week; tagging mortality and displacement offish while tagging did not appear to affect estimates of fishing mortality.

A SAS program was designed to compile and summarize data collected by rotenone sampling. The program is designed to accept data in a variety of forms, providing a statistical summary of number, weight and percentage composition for all species and also a separate summary for harvestable gamefish and! or forage fish. Options are available to calculate weights for fish collected on second and third day pickups with weight-length relationships established from first day fish for either individual fish or by size groups.

We examined the accuracy and application of sequential sampling to determine structure of fish stocks, using electrofishing data for largemouth bass (Micropterus salmoides) as an example. Structure of the stock was categorized with the index of Proportional Stock Density (PSD), which is the percentage of quality-size fish in the stock. Minimum stock and quality sizes for largemouth bass were defined as 20 and 30 cm, respectively. Sequential sampling is based on data evaluation during collection. An average reduction in sample size of 42% is realized when populations are sampled sequentially rather than continuing to an endpoint (n= I00 fish), because sampling ends as soon as a decision is reached. Fish stocks can be categorized based on PSD, i.e. Oto 39%, 40 to 60%, or 61 to lOO%, or a point estimate of PSD with confidence limits can be calculated.

Culturability of snook (Centropomus undecimalis) was evaluated in laboratory studies during the summers of 1975-1977. This is the first report of snook being reared from artificially fertilized eggs. No snook survived longer than II days in the 1975 experiments, although about 50 and 250 were reared through metamorphosis and beyond in the experiments of 1976 and 1977, respectively. These snook were reared in closed saltwater rearing systems for 14-16 days, after which they were converted to fresh water and stocked in 0.01 ha ponds. In our studies, snook were not cannibalistic at sizes less than 20 mm TL; withstood low overnight dissolved oxygen concentrations of less than 1.0 ppm; and could be converted to fresh water at 15 days ofage. Snook 15 days and older are relatively hardy, and if procedures could be developed to rear them to this age in large numbers, culture of fingerling snook could become a routine matter.

In 2 trials during 1976-1979, juvenile red drum (Sciaenops ocellata) were reared to marketable size (454 g) in 0.08-ha, brackish-water ponds at the Claude Peteet MaricuIture Center. In Trial I, survivors from a nursery pond were stocked in 2 production ponds, fed a commercial feed, and harvested when 394 or 532 days old. Less than I% of drum from the first harvest were marketable, and yield was 787 kgl ha with 21O-g mean weight, 89% survival, and 2.8 feed conversion. Twenty-one percent from the second harvest were marketable, and yield was 1,062 kgl ha with 335-g mean weight, 75% survival, and 4.6 feed conversion, In Trial II, red drum from a second nursery pond were restocked in periodically drained production ponds, fed commercial feeds, then harvested when 715 days old. Standing crop of drum was 2,292 kg/ha during Trial II, and 33% of the drum were marketable at harvest.

In September 1974 the Texas Parks and Wildlife Commission banned the use of plastic baits on trotlines because these baits were thought to be selective for small «500 mm) red drum (Sciaenops ocellata). The size of red drum landed by commercial fishermen before (1972-1974) and after (1974-1978) the ban was compared with the size of fish collected during Texas Parks and Wildlife Department trammel net surveys in order to determine whether the ban had any effect on either the commercial catch or fish availability. Fish landed by commercial fishermen were significantly larger after the ban then before; therefore, it appears that plastic baits are selective for small red drum and that the ban resulted in the desired effect. The larger red drum in the commercial landings as compared with trammel net caught fish may have resulted from such factors as fishing method (hook size and bait type), fishing location and / or culling.

Biomodal spawning peaks, as determined by the gonadosomatic index, were noted for the spotted seatrout (Cynoscion nebulosus) in the Barataria Bay, Louisiana, system for 1976 and 1978. Males matured earlier in the season and at a smaller size than females. Males were found to have sound producing capabilities. Fish spawned throughout the bay regardless of water depth or substrate. Spawning seemed to occur in the northern portion of the bay later than in the southern portion. Photoperiod and temperature were the only exogenous factors found to have a direct relationship with spawning.

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.