Journal of the Southeastern Association of Fish and Wildlife Agencies

Standing crop of estuarine fisheries, as determined by extensive rotenone sampling, ranged from 17.6 to 1,605 kg/ha; overall average was 393.8. The most abundant species in numbers were gulf menhaden, Brevoortia patronus (54.6%); anchovies, Anchoa sp. (10.7%); and striped mullet, Mugil cephalus (6.6%). Of the 8,322 kg of fish collected during the study, red drum, Sciaenops ocellata, represented 32.2%, followed by menhaden (16%) and striped mullet (11.5%). First day rotenone samples were not sufficient for quantitating species abundance. Rotenone eollections indicated that trawls were highly selective (P<.01).

Control of population density in southern Illinois farm ponds was achieved by stocking F, hybrid sunfish of the male bluegill (Lepomis macrochirus) X female green sunfish (L. cyanellus) and the male redear sunfish (L. microlophus) X female green sunfish with largemouth bass (Micropterus salmoides). Four of 30 ponds sampled were contaminated by nondesirable species from the watershed. Little or no recruitment of the F, generation occurred in ponds containing largemouth bass. In those populations where the hybrids were supplementally fed and bass were present, the F, bluegillX green sunfish hybrid averaged 159 g at annulus 3, and 199 g at annulus 4. In nonfed populations with bass this hybrid averaged 148 g at annulus 4. The F, redear sunfish X green sunfish hybrid averaged 127g at annulus 4 in nonfed populations with bass.

Anhydrous ammonia was applied to ponds at average rates of 18-40 ppm to evaluate its use as a fish toxicant and aquatic herbicide. Ponds contained toxic levels ofammonia for 3-4 weeks after applications, depending on concentration, water temperature and other factors. A regression model was developed to estimate specific dissipation times. Application of15ppm ammonia effected a high percent mortality to all fish species observed. Complete fish kills occurred at approximately 30 ppm ammonia. Any concentration above 15 ppm temporarily controlled most vegetation, regardless of season. Benthic organisms were reduced but not eliminated by any treatment. Anhydrous ammonia was found to be relatively inexpensive compared to other fish toxicants and aquatic herbicides.

Five yearling northern pike (Esox lucius). muskellunge (Esox masquinongy), or their F, hybrid ("tiger muskie") were stocked in duplicate 0.2-ha ponds in April, 1974. Two additional ponds were stocked with a combination of five fish of each of the three forms. In 58 hours of angling from April to September, northern pike were 3.1 and 4.2 times more vulnerable than tiger muskies and muskellunge, respectively. No fish were caught in 18 hours of fishing from 15 June to 13 August. Repeat catches accounted for 35. 6% of the total catch; hooking mortality was negligible (1.7%).

The Reservoir Committee, Southern Division, American Fisheries Society, undertook to measure the influence of stocked predator fishes on existing fish populations and sport fishing in selected reservoirs through a coordinated interagency study. Field data collection consisted of (1) fish population biomass estimation, (2) limnological survey, and (3) sport fish harvest estimation, with data being collected in 1972 and 1973. Twenty-six reservoirs, totaling 368,000 acres, were included in the project. The work plan used to standardize field data collection is described. Six years were required to plan, execute. analyze, and publish the results.

Sixteen of the 26 predator stocking evaluation (PSE) reservoirs were stocked with striped bass during 1967-71 and harvest of them by anglers was recorded in 10 reservoirs in 1972 and/or 1973. Walleye were stocked in nine of the PSE reservoirs and were harvested in six of them during the study period. Probable reasons for stocking success or failure are discussed in the accompanying PSE papers.

Estimates of angling effort and sport fish harvest in 24 predator-stocking-evaluation reservoirs in 1972 and 1973 indicated mean annual angler-effort was 31.1 hours per acre and total harvest was 18.4 pounds per acre. Harvest-rate was 0.7 fish per hour or 0.6 pounds per hour. Average annual harvest of striped bass was 0.5 pounds per acre; walleye 0.3 pounds per acre. Striped bass harvest was positively related to dissolved solids content and water level fluctuation but negatively related to mean depth. Walleye harvest was positively related to mean depth and negatively to reservoir area. Establishment of significant fisheries for both striped bass and walleye in a single reservoir is improbable. No significant correlation was found between the harvests of stocked striped bass or walleye and the harvests of other sport fishes. Insofar as harvest data reflect production there is no evidence of competition between introduced and indigenous predators in the reservoirs sampled.

The cove rotenone sample technique was used to estimate standing crop of fishes in the 23 reservoirs selected for the Predator Stocking Evaluation (PSE). Estimates ofadjusted standing crops were derived by expanding the observed standing crop of fish in a cove sample by compensation factors for incomplete recovery of fish in the sample and for different shoreline-open water distributional patterns of various fish species and size groups. Results of 138 rotenone samples indicated that the mean adjusted standing crop of fishes in the PSE reservoirs was 451.1 pounds per acre, an increase of 79 percent over unadjusted crop. Adjusted crop estimates of major taxa in pounds per acre were: Esox sp., 0.8; white bass, 3.7; striped bass, 0.6; black bass. 30.2; crappie, 17.8; walleye, 0.4; gars, 2.5; bowfin, 3.3; catfish. 39.2; clupeids, 148.3; minnows and silversides. 3.1; white perch and yellow bass. 1.1; sunfishes. 82.2; darters, 1. 7; yellow perch.

Relations between environmental variables and fish standing crops were examined in 1972-73 as part of a Predator-Stocking-Evaluation of reservoirs, sponsored by the Reservoir Committee, Southern Division of the American Fisheries Society. High volumes of flow and increased water exchange rates in 1973 were associated with increases in fish standing crops and changes in the size structure of fish assemblages in some study reservoirs. Reservoirs with higher inherent water exchange rates also supported larger standing crops than those with lower exchange rates. However, highly variable responses of fish populations in different reservoirs to environmental change reflect the importance of other physicochemical and biological interactions not measured in this analysis. Combinations of environmental variables explained from 41 to 67% of the variation in selected standing crop components.

The method advanced for estimating prey-predator relations in reservoirs is based on fish standing crop data derived from samples collected in rotenone-treated coves in 23 reservoirs. The sampling, in August 1972 and 1973, was part of a cooperative study conducted under the auspices of the Reservoir Committee, Southern Division of the American Fisheries Society. Estimates were made of sizes ofprey species which predators with various mouth sizes could swallow; lengths ofall species ofpredators were then adjusted to equal the lengths of largemouth bass of equivalent predatory capability; and a computer program was develaped to calculate biomass of prey available to predators in length classes equivalent to 1-inch length classes of bass 1- to 28 inches long. Results indicated that 50% of the populations sampled were deficient in available prey. Stocking ofadditional predators in these instances would be deemed inadvisable.

Satisfactory procedures were developed for the artificial propagation of snook, Centropomus undecimalis, as were methods for capture, care, transport, and handling of the broodfish. Milt stored at 40' F. up to 12 hours was satisfactory for fertilization. Fecundity was determined to be approximately 45,000 eggs per pounds of body weight. Fertile eggs were bouyant at salinities greater than 2(1'/0<> Lack of agitation during the first 6 hours of incubation proved critical for consistent embryo development. Hatching occurred between 24 and 30 hours after fertilization at incubation temperatures between 82' and 87" F. Fry culture efforts were limited to intensive culture techniques in the laboratory.

Spotted seatrout were maintained in an indoor tank (6 x 3.3 x 1.5m). Temperature and light were adjusted to simulate the seasons. When the light regime equaled 15 hr light and 9 hr dark and the temperature was 26 C. the spotted seatrout began to spawn. They continued to spawn during each of 13 consecutive months for a total of 82 spawns. Eggs were collected from the filter box with glass beakers and placed in 74-liter aquaria. The eggs hatched after 18 hr. Newly hatched seatrout were fed rotifers (Brachionis plicatilisland brine shrimp (Artemia sp.). Descriptions and illustrations are provided of the tanks, aquaria, lighting equipment. collecting gear, and plumbing. Procedures and methods for collecting adults, for including them to spawn. for collecting the eggs, for rearing the larvae. and for growing food for the larvae are described in detail.

Total dissolved gas, dissolved oxygen, dissolved nitrogen, pH, conductivity, temperature, and turbidity were monitored to determine diel and annual changes in a mariculture pond and in aquaria supplied with water discharged from a power plant. The diel and annual ranges of all hydrological parameters were greater in the pond than in aquaria. Diel patterns were similar in both cases but the amplitude was attenuated in the laboratory aquaria. Gas bubble disease (OBD) developed in 17 marine and estuarine fishes and in grass shrimps in the laboratory. GBD was more prevalent in aquaria at higher temperatures than in aquaria at lower temperatures. The disease occurred only in the winter months and was simultaneously found in fish in aquaria and in fish cultured in cages in the discharge canal.

Flow-through seawater bioassays of 28-days duration were conducted with the organochlorine pesticides heptachlor and toxaphene to detennine their toxicity to and bioconcentration by embryos and fry of the sheepshead minnow (Cyprinodon variegatus). At technical heptachlor measured concentrations of 4.3, 3.5, 2.2, 2.0, and 1.2 u/1 (ppb), test animal survival was 1, 5, 61, 79, and 88%, respectively. At toxaphene measured concentrations of 2.5, 1.1, 0.6, 0.3, and 0.2 1u/1, test animal survival was 10, 85, 79, 88, and 80% respectively. Average standard length of fry continuously exposed from fertilization to heptachlor concentrations of 4.3 and 3.5 1u/1 was significantly reduced (a; = 0.01). Concentration factors (concentration in fish/measured concentration in water) for heptachlor averaged 3,600 and for trans-chlordane averaged 8,600. Heptachlor epoxide and cis-chlordane were also present in the fish. Concentration factors for toxaphene in fry averaged 9,800.

This study was designed to compare the catch of sport and rough fishes and to determine the survival ofsport fishes captured by commercial gill nets in Texas reservoirs. Commercial fishermen were required to submit monthly reports for 1 yr (April, 1973 through March, 1974) on their rough fish harvest and on the number and species of sport fishes caught and released. The catch was recorded from monthly samples of commercial harvest on Lakes Sam Rayburn, Whitney, Somerville and B. A. Steinhagen and from quarterly samples on Lakes Livingston and Cedar Creek. Netting mortality of sport fishes was determined by holding the fish for 17 days following their capture. Data indicated commercial fishermen did not report their catch accurately. Mortality studies showed largemouth bass and crappie suffered almost total netting mortality; catfishes exhibited better survival 163-100%). Losses were small and apparently not harmful to the sport fish populations.

Primary productivity and nutrient concentrations were compared between the periphyton community on a freshwater artificial tire reef and the littoral phytoplankton in Smith Mountain Lake, Virginia, during the months of July, August, and September 1974. Primary productivity and nutrient concentration of the periphyton community were several times greater than that of the littoral phytoplankton. The periphyton community was dominated by pennate diatoms and filamentous green algae. Productivity measurements of the reef periphyton were on the same order of magnitude as the highest periphyton production rates reported in the literature. High Productivity of the tire reefperiphyton supports the hypothesis that freshwater artificial reefs support increased densities of fish and invertebrates by enhancing the productivity of aquatic environments.

To determine the effects of a large-scale rotenone renovation on a fish community and sport fishery, a 5-yr study was conducted on Sheldon Reservoir, a 485-ha Texas reservoir with small sport fish populations and poor fishing. The lake level was lowered and the remaining water treated with liquid rotenone. Gill nets, seines and a creel survey were used before and after treatment to evaluate this renovation. The relative abundance of sport fish populations increased from 17.54% (by weight) before treatment to a high of 46.27% after the renovation and restocking. Although high populations of sport fishes were maintained, turbid water conditions adversely affected fishing pressure and success, and prohibited accurate long-range evaluation of the effects of this treatment on the fishery. Cumulative cost/benefit ratios for the first 3 yr after renovation were 1:1.63, 1:1.20 and 1:0.93 consecutively.

The effectiveness and selectivity of monofilament and multifilament gill netting and area rotenone sampling in a shallow, 15.3-ha impoundment were determined. Estimates of species present, relative abundance, length-frequency distributions and standing crops were determined by the sampling techniques and compared with total fish populations estimated by rotenone treatment of the entire impoundment. Each sampling device furnished close approximations of species present and relative abundance of dominant fishes, but gill netting was the most economical method of determining these two statistics. Area rotenone sampling provided the only adequate length-frequency data. Rotenoning surveys misrepresented the overall standing crop of fishes, but apparently furnished accurate standing crop estimates for sections of the impoundment sampled.

The use of fin-clips and dart tags for detennining recovery efficiency in summer cove rotenone samples was compared. Using a standardized cove sampling methodology, fin-clipped fish were recovered from 69 coves at an overall rate (%) of 52.4 ± 4.7 (2 S. E.), while in 21 coves 73.6 ± 3.0% of the dart-tagged fish were recovered. As the sample season progressed recovery efficiencies for fin-clipped fish showed a consistent improvement, however, neither seasonal nor year-to-year means was as high as dart-tagged estimates. End of season values with both marking methods showed a recovery efficiency of about 70 percent in the reservoirs surveyed.

The perfection of culture techniques for the channel catfish (Ictalurus punctatus) has been aided by the commercial demand for fingerlings, by the fact that the catfish is "precocial" by the time the yolk sac is absorbed, is not cannibalistic, and readily utilizes artificial feeds early in life. Several techniques have been developed for producing catfish fingerlings, but the method that appears most acceptable for the production of large numbers of fingerlings is by the pond spawning/trough incubation technique. The principal advantages of this method are that it makes possible a high survival of fingerlings and control ofdensity in the rearing ponds. Where it is desired to mate selected individuals, the aquarium method or the pen method are particularly attractive. There is interest in tank rearing of fingerlings; however, due to the characteristics of the channel catfish, the authors question that this method will have any advantage over the pond method.

Stocking of small fingerling catfish into rearing ponds at a density to give the optimum number and weight for harvest at edible size gives a low gain per acre per day during the first half of the grow-out period. Use of a much heavier stocking rate initially, with periodic division or splitting of the stock shows promise of significantly increasing the gain per acre per day. Use of two divisions gave a gain per acre per day ofabout 25 pounds for the first phase and 10 pounds for the second. A hypothetical example is presented which should make a gain of 12 pounds per acre per day possible over a 360 day calendar year period under central Alabama conditions. Several possible ways the growing stock could be divided are listed.

A telephone and personal survey of all known Arkansas fish producers was made during the first quarter of1976 to determine the extent of change in aquaculture production during the past three years. The survey indicated that although intensive pond production has been reduced by about 4,050 hectares, the economic value since 1972, because of higher prices received for the products, has increased by 16.8% to $24,191,700. Growth in the industry has slowed in recent years due to narrowing profit margins and changes in prices and allotments for other agricultural crops.

Cultural technology is adequate to produce crawfish in ponds with water quality a main consideration. Occurrence of small stunted crawfish has been reduced by increasing trapping frequency. A mechanized harvester and more efficient traps and bait are needed to relieve labor problems. The processing industry must have a mechanical peeler and utilize traditional shrimp freezing technology to extend shelf life and markets. Marketing is a key to sustained pond production. Prices of crawfish will increase as processors and live market sales compete for the raw product. Expansion of the market for both imports and exports will be on a national and intemational scale.

A total of 710 largemouth bass was collected from a 4047 ha coastal freshwater marsh in Southwestern Louisiana. Seven age-groups (()-VII) were present in the marsh. Annual increments were smaller for the first 3 years of life when compared to other Louisiana areas, but greater during the remainder of life. Condition factors were comparable to those obtained by other Louisiana authors. Food habits of young of-the-year bass >95 mm in length were not different from age groups I and II. Fish and adult odonates were the principal forage for bass in the summer. During the winter, stomachs of bass from age groups ()II contained principally fish and freshwater shrimp whereas those from age groups ≥III contained predominantly fish.