Journal of the Southeastern Association of Fish and Wildlife Agencies

Cage and raceway culture of striped bass, Morone saxatilis (Walbaum), in brackish water was conducted at the Marine Resources Laboratory, Dauphin Island, Alabama during the period 1July 1971 to 2 November 1971. The effects of two feeds and two feeding regimes on the growth, food conversion and survival of fingerlings cultured in \\12" mesh cages (I yd.3) were studied. Growth, food conversion and percentage survival was better among fish fed the trout chow. The feeding regime of four times daily enhanced growth and survival among fish fed either of the two diets. Striped bass cultured in a 760-gallon circular raceway increased their weight by 832 percent over a 93 day period. Overall food conversion and percentage survival was 2.0 and 94.1, respectively. Results of a stocking density experiment involving fish stocked in cages at rates of 100, 200 and 300 per yd. 3 are discussed.

Twenty suspended l-m3 cages were each stocked with 300 five- to six-inch channel catfish fingerlings to allow for the evaluation of five feeding regimens, each replicated four times. The experiment began April 15 and terminated October 21, providing for a 180-day feeding period. The daily feeding rate was 4% of biomass initially and decreased to 1.5% of biomass during the latter phase of the feeding trial. The experimental feeds were nutritionally complete, low-fiber, expanded (nonsinking) 3/ 16-inch diameter pellets. Treatments (diets) I through 3 contained protein levels of 40,35, and 30%, with 38% of the protein in each diet coming from fishmeal and the remainder from plant sources. Diet 4 was designed to contain the same theoretical amino acid composition as diet I with only 17.5% of the protein coming from fishmeal and the deficient amino acids supplemented in isolated form.

This study was designed to compare the growth, mortality, and catchability of three species of catfish, blue catfish (lctalurus furcatus), channel catfish (I. punctatus), and white catfish (I. catus), in an artificially fed fishing pond. After stocking in October, 1968, the pond was fished a total of 35 days in two years (1970 and 1971). All remaining fish were then removed. The pond was "contaminated" primarily by brown bullheads and bluegills, with bullheads accounting for 648 pounds of the 2320 pounds per acre removed at the end of the study. Although 90 pounds of bluegill per acre were harvested during the 1971 fishing season, only 62 pounds per acre were present during eradication. Catch rates of all three catfish species were low throughout most of the study. Catch rates of blue catfish and white catfish were lower than channel catfish. "Natural" mortality of blue catfish was less than channel or white catfish.

For transfer of fingerling fathead minnows (Pimephales promelas) from spawning ponds to growing ponds, the optimum combination of brood-fish population density and sex ratio in the spawning pond was 19,200 fish per surface acre and five females to one male. Fingerling production from this combination amounted to 1,524,500 fish. Fathead minnows utilized spawning boards placed up to 5 ft deep, and they also utilized boards placed without reference to the substrate. Larger nest sites encouraged larger egg deposits. Nests were crowded together as effectively by restricting available nest sites as by providing visual isolation or territorial markings. Post-spawning mortality of adults ranged from 20% to 91% with higher survival of females than males.

A method for the controlled production of largemouth bass, Micropterus salmoides, Lac. fry is described. The method was based upon use of artificiallyfed brood fish which were stocked into small earthen ponds equipped with nylon felt spawning mats. Eggs deposited on the mats were separated, cleaned and incubated in a Heath Vertical Incubator. Fry hatched in one to two days and were held until swimup in holding troughs or shipped during the yolk sac absorption stage. A trial of the technique in 1972 resulted in approximately 2,714,000 eggs being collected from 563 fish stocked in seven O.I-acre ponds. From these eggs, 1,564,000 fry were hatched and survived (57.6 percent) to swimup or for shipment as sac fry. Twenty-two percent of the eggs collected were infertile according to examination of samples removed during processing. Subtracting this percentage from the total number of eggs collected gives an estimated 2,117,000 which could have hatched.

Populations of midges are a general nuisance around commercial catfish ponds in the Mississippi Delta, Abate(R) [(O,O,O',O'-tetramethyl O,O'-thiodi-pphenylene phosphorothioate) American Cyanamid Company] is recommended for midge larvae control in aquatic areas at a concentratIOn of about 2 ppb. Data in this study show that the LC50 ofAbate to channel catfish is between 5 and 7 ppm. This represents a wide safety margin that should insure Abate to be non-toxic to channel catfish when used at the recommended rate for midge larvae control.

In 1968 fisheries personnel of the Tennessee Game and Fish Commission began constructing and evaluating stake beds made of sawmill strips as tools to help fishermen harvest more crappie from Kentucky Reservoir. They are: hammer d riven type; driver driven type; portable pre-fab type. Crappie concentrate readily on all three types with variations occurring due to location and seasonal fish movement. Over 128 hours of documented fishing on stake beds by the author produced 6.6 crappie per hour as opposed to 1.8 crappie per hour on control cover areas. A five year mean for crappie fishermen on the same reservoir is 0.998 crappie per hour.

Floy® dart tag (FD-67 international orange) loss of 78% was discovered among largemouth bal's held in hatchery pond~ for three months.Sepa!a!io~of the #20 tubing from its monofilament anchor accounted for 81% of the losses, while dislodgement of the anchor from fish occurred in only 19% of the losses. Since ponds were free of vegetation which could entangle the tag and contained only tagged bass and bait fish, tag loss was assumed to be the result of bass pulling tags from each others' backs. To test this theory and determine differential retention for other types of Floy® dart tags, further studies were conducted. International orange, green, and brown FD-&7 tags sustained 58%, 62%, and 63% retention, respectively, on largemouth bass held in a hatchery pond tor 3 months. Differences in retention were nonsignificant in Chi-square testing.

Sampling of fish for the purpose of estimating standing crop, annual net production, and the degree of relationship between these two variables was carried out in four Oklahoma farm ponds in 1965. Fish populations were assumed to be at or near the upper asymptotic level, and fishing was almost nonexistent. Annual rate of turnover varied less from one population to another than did standing crop. Turnover rates for most species appeared high, but this may be the normal situation in older ponds whose fish populations are not being harvested. Bartlett's three-group method for Model II regression was used to obtain the prediction equation: annual net production =0.3465 + 0.6088 (standing crop). This equation showed by its positive slope that annual net production increased as standing crop increased. The coefficient of determination, r2=0.92, indicated a strong relationship between standing crop and the annual net production of fishes.

An ultrahigh-frequency electromagnetic field (2,450 ±20 megahertz) is lethal to floating aquatic plants. Preliminary experiments indicate specie sensitivity varies within the duckweeds. Laboratory experiments indicate their Median Tolerance Limit is approximately 16.7 joules/ml, for our experimental conditions. However, field simulated experiments with soil banked test containers indicate higher energy levels will be necessary for field control.

During 1968-1971 a total of 494 flathead catfish were tagged with ring and/ or spaghetti tags. Of 175 recaptures, III were by the authors and 64 were by fishermen. Application of ring tags to the pectoral spine and spaghetti (T-bar, 1chor type) tags to the operculum is described. The anchor tags were applie t to the operculum by piercing the bone with the needle of the tag applicator. Ting tags of monel metal were held totally by encirclement of the base of the pectoral spine. Rates of tag loss were measured from fish marked and recaptured March 1968 through October 1971. For both tag types, the rate of tag loss was linear the first year. but exponential the second year after tagging. A discontinuous linear regression. separating the first and second years was used to calculate tag loss. The rate of tag loss the first year was 0.0665%/ day for ring tags and 0.0830%/ day for spaghetti tags; the second year.

In the period 1936-1941, smallmouth bass nests were counted in the Main Stem and South Fork of the Shenandoah River. Counts were made during the smallmouth bass spawning season when waters were clear, usually May 1-15. Due to eutrofication, the South Fork and Main Stem water now remains clear for only a few days. The enumeration and study of bass nests has been made more difficult due to the sudden development of blooms of algae. High levels of phosphorus and nitrogen in the South and North Forks and the Main Stem are believed to be the cause. Total phosphate ranged from 0.33 to 4.80 parts per million in the South Fork and from 0.23 to 1.50 ppm. in the Main Stem. The highest seasonal averages occurred in the spring and fall. In the North Fork, total phosphate ranged from 0.14 to a maximum of 1.40 ppm., with the highest seasonal averages occurring in the spring and summer. Orthophosphate ranged from 0.30 to 2.30 ppm. in the South Fork, and from 0.14 to 1.04 ppm.

Apparently extensive fish mortalities were reported to have occurred in the North Fork Pound Reservoir during February, 1969 and February, 1970. A study was initiated in September, 1969 and continued through October, 1970, in order to ascertain the causes of these mortalities. Chemical water analyses disclosed that the lake pH varied from 4.0-6.4, with a mean near 5.0. The heavy metals, copper, mercury, zinc, iron and manganese were found in the lake waters at levels reported to have chronic effects on fish. Biological investigations revealed fish populations were at low levels (smallmouth bass, channel catfish, largemouth bass, black crappie, green sunfish, bluegill, redear sunfish and brown and yellow bullheads). Reproduction of largemouth bass, green sunfish and black crappie appeared to be nonexistent. Standing crops of zooplankton and phytoplankton appeared extremely low.

Organochlorine-resistant mosquitofish from an insecticide contaminated environment in the Mississippi Delta showed a 3.4-fold tolerance to pyrethrum when compared to a susceptible strain. The 24-hr LC50 values for pyrethrum in susceptible and resistant mosquitofish were 27 and 93 ppb, respectively. Results of studies with sesamex, an inhibitor of mixed-function oxidase (mf0) enzymes, indicated that the tolerance to pyrethrum is partially, but not solely the result of increased levels of mfo enzymes. Additional studies with allethrin show that increased carboxylesterase enzyme levels cannot explain the pyrethrum tolerance which was not accounted for by mfo enzymes; thus yet another mechanism must be involved. Resistant mosquitofish that had been maintained in an insecticide- free environment for several years also possessed a tolerance to pyrethrum but to a lesser degree than the original parents from the insecticide- contaminated area.

The purpose of this investigation was to determine the effect of continuous exposure of pre-adult Daphnia magna to low, presumably sub-lethal doses of phenol. The experimental data were obtained through use of a standard 24-hour toxicity bioassay and a modified long-term toxicity bioassay. Control and test animals were cultured in a synthetic pond water and fed with dried yeast. Six concentrations of phenol were tested. Data were applied to least squares linear regression analysis, multiple linear regression analysis, crossed covariance analysis, and several related tests in order to quantitatively interpret the total effects of the chronic poisoning. It was found that phenol exhibited strong interaction with temperature of the culture medium and with the age of the individual to retard ecdysis. This results in a prolonged generation time. Mortality was also increased and reproduction was greatly inhibited.

An investigation was conducted concerning the effect of mirex bait on production and survival of red crawfish, Procambarus clarki (Girard), in rice fields of southern Louisiana. Twenty experimental plots were stocked with 2,000 brood crawfish (50 pairs per plot). Each plot was randomly assigned to one of four treatments: (1) conventional rice insecticides, malathion and carbofuran; (2) mirex alone; (3) mirex in conjunction with malathion and carbofuran, and; (4) untreated controls. Mirex bait (0.3 per cent technical material) was applied at the rate of 1.25 pounds per acre in three applications, approximately 90 days apart. Statistical analyses of data revealed no significant differences among treatments in crawfish size, sex ratio, and weight yield, whereas the differences among treatments in number harvested were significant (P .05). Plots treated with mirex alone produced the fewest crawfish (3,642) and control plots the most (5,667).

Striped bass eggs, 24 hours after fertilization, and newly-hatched fry were tested to determine their sensitivity to zinc and copper. This study with those of Hughes will provide information on the most sensitive stage ofthesefish to acute exposure to lethal levels of zinc and copper. Newly-hatched fry were more sensitive to both zinc and copper than were eggs, but copper, at the lowest concentration used, retarded hatching. Eggs and fry were more sensitive to copper than to zinc. In order for acute toxicity studies to have a predictive value, confidence limits need to be placed on the TLm values obtained from toxicity studies. Results obtained from three different methods of providing confidence limits are discussed and the relative merits of each method are compared.

This study provides an evaluation of the benthic faunal characteristics of the cold tailwater of Greer's Ferry Reservoir on Little Red River. This Ozark stream is characterized by cold and non-turbid water, and periodic drastic vacillation of water level, the results of a deep water discharge for hydroelectric generation. For these reasons the benthic macroinvertebrate community is qualitatively limited. Pool and riffle habitats were sampled at six-week intervals at each of three stations established between 500 m-23 km below the dam. Most physicochemical characteristics measured were found not limiting, except water temperature and current velocity. Benthic organisms were limited to 59 taxa. Longitudinal zonation was characterized by an increase in diversity downstream with 15,32, and 41 taxa collected at Stations 1,2, and 3, respectively. Overall dominant organisms numerically were oligochaetes, chironomids and isopods.

Teaching natural resource management is especially difficult because of the importance of experience in making management decisions. Most methods for allowing natural resource students to gain management experience in the classroom have not been entirely satisfactory. Computer implemented simulation of natural resource problems allows educators to provide management experience to students. TROUT, a learning exercise which simulates a coldwater lake fishery, is discussed as an example of the role of these teaching tools.

The level of natural hybridization in Lake Texoma between Dorosoma cepedianum and D. petenense for the years 1962-63 and 1968-69 was determined to be 2.5 and 1.7% respectively. The two species have been sympatric in that reservoir since 1957. Male and female hybrids with well developed gonads were collected. Eggs from a hybrid were fertilized experimentally with milt of D. petenense and produced viable larvae. Hybrid fry were produced in the laboratory by crosses between D. cepedianum males and D. petenense females but not the reciprocal. Spawning of the two species is discussed in relation to the possible means of natural hybridization. Natural hybridization between the clupeid species Dorosoma cepedianum and D. petenense was reported by Minckley and Krumholz (1960). They cited as the probable cause, the less abundant D. petenense joining groups of spawning D. cepedianum. Hybrids were first identified in Lake Texoma in 1960 by C. D. Riggs and G. A.

The possible effect of threadfin shad stocking in Dale Hollow Reservoir on the growth of five predatory species was measured by analysis of scale samples taken before and after threadfin stocking. There was no significant change in growth rate of largemouth bass, Micropterus salmoides; smallmouth bass, Micropterus dolomieui; and spotted bass, Micropterus punctulatus. There was a significant increase in growth rate of walleye, Stizostedion vitreum and white crappie, Pomoxis annularis.

Stomachs from angler-harvested specimens of 259 largemouth bass, Mieropterus salmoides, 263 spotted bass, M. punctulatus, and 256 smallmouth bass, M. dolomieui were collected from the mid-lake region of Bull Shoals Reservoir during March 1971 - February 1972. Stomach contents were compared on the basis of frequency of occurrence, weight, and seasonal distribution of food items. Black basses were piscivorous in feeding habits during the summer and early autumn, with young of the year shad contributing substantially to the diets. Utilization of young shad by adult basses followed shad spawning by six to eight weeks. During late autumn and in the spring, food habits of the three species varied. Largemouth bass stomachs contained primarily crayfish and centrarchids during the late autumn and crayfish, yearling shad and unidentified fish remains during the winter and spring months. Spotted bass fed primarily on crayfish throughout the period.

The growth history of largemouth bass in Lake Carl Blackwell is described. Variation in annual increments in growth of largemouth bass age groups I-III are examined in relationships to mean annual water level 1962 through 1967, when the annual average lake level was declining. Weighted mean average total lengths (mm) to the end of each year of life, i.e., to annulus formation which occurred in May, were: 140 (I); 279 (II); 369 (III); 425 (IV); 462 (V); 485 (VI); 504 (VII); and 53 I (VIII). Growth in the first year was positively correlated (r=0.85, P<.035) to the average annual lake level. In the second year the relationship was negative (r = -0.95, P<.004), that is, annual increments in growth in the second year of life were inversely related to lake level. Growth increments in the third and fourth years also were negatively correlated with lake level but the correlation was non-significant (P>.05).

This paper describes the results of a length and weight at maturity study of channel catfish, Ictalurus punctatus, and blue catfish, Ictalurusfurcatus. Total length-collarbone length and collarbone length-total length conversion factors were determined and are presented for future biological references. Data were collected from the marshes of Southwest Louisiana.