Journal of the Southeastern Association of Fish and Wildlife Agencies

Emulsifiable oil preparations of benzene hexachloride were found to be 25 times more toxic to golden shiners than wettable powder formulations containing the same level of gamma isomer. Tests of the individual components of the oil preparation other than the pesticide indicated that none of these was toxic to fish at the levels normally applied. The addition of a hydrocarbon solvent to a formulation increased the toxicity many times. No difference was noted in the toxicity of the active ingredient used in the various formulations. Lethal dosages for copepods were not affected by formulation differences. Although aqueous solutions of the oil preparation killed much more quickly than the wettable powder, similar levels of activity produced equivalent results.

Experiments on rearing largemouth bass fingerlings to a size of 4-6 inches total length in rearing troughs and tanks are described. Fingerling fish 1.5-3.0 inches in length which had been started in earthern ponds on natural food were trained to take artificial food employing ground fresh or frozen fish as a starting diet. Following the initial training period the fish were fed a prepared ration composed of varying amounts of frozen fish or beef liver mixed with a dry trout food. Data on survival, growth, food conversion and special problems encountered are presented. The rate of growth appeared to be slower in the controlled environment than had been observed in ponds. A six to ten-fold increase in weight was measured in two different years for a feeding period of 73-120 days.

Materials used for feeding fish may be subjected to drying, freezing, grinding, radiation, hard pelleting and expansion pelleting. During these processes, physical and chemical changes occur due to inherent enzymes, contamination by microorganisms, oxygen, temperature, pressure and ionization of molecules. These changes are not reflected in the gross composition of the major nutrient classes (protein, fat, carbohydrate, ash), but in the intrinsic nutrients, organic additives and digestibility. Experimental work showed the hard pelleting process to be destructive to added enzymes.

Pond fertilization with N-P-K has been used in the Southeast for the past 20 years to increase fish production and to control aquatic weeds and mosquitoes. In ponds which had been fertilized previously for a IS-year period with N-P-K, no significant decrease in production resulted from omitting both nitrogen and potassium from the fertilizer mixture during a four-year ‘experimental period. It appeared that adequate nitrogen for plankton production became available from nitrogen fixation by bacteria or algae and from the organic matter and ammonium stored in the bottom muds. Omission of phosphate, however, caused a decrease in production during all four years of the experiments. With no fertilization, production decreased during a two-year period; in the third and fourth years, production was approximately the same as in ponds that had never been fertilized.

Complete fish mortality associated with the development of high populations of dinoflagellates (Gymnodinium spp.) was observed in 1960 in a 9.5 acre fresh-water lake at Baton Rouge, Louisiana. Toxicity of the water samples containing the algae appeared to be related to the increased pH, length of exposure to sunlight and concentration of algal cells. Filtration with activated carbon removed the toxic effects. Laboratory tests offered data to explain the course of the fish mortality in the lake.

Weekly measurements were made of light intensity, dissolved oxygen concentration, and water temperature at selected depths in five earthen experimental ponds. Measurements were made on a given pond on the same day between 7:00 a.m. and 8:45 a.m. and again between 10:00 a.m. and 11 :45 a.m. The depth at which the average light intensity, as measured with submersible Weston Photronic photoelectric cells, was less than 1 per cent incident radiation varied from 2.5 to 7.5 feet among the ponds, depending on the degree of Microcystis infestation. Generally, at depths where the average light intensity was not in excess of 1 per cent incident radiation, the average dissolved oxygen concentration was not in excess of 1 ppm. The average dissolved oxygen concentration in the pond with the most dense growth of Microcystis was usually less than 1 ppm. below 5 feet and less than 1 ppm below 7.5 feet in the ponds with the least amount of Microcystis.

A total of 429 female striped bass were treated with hormones during the spring spawning seasons of 1962 and 1963. Of this number, 118 (26.6%) were induced to ovulate while held captive. One hundred of the ovulated :fish were treated with chorionic gonadotropin while used alone or in combination with other preparations. Eighteen of the ovulated fish were treated with follicle stimulating hormone while used alone or in combination with preparations other than chorionic gonadotropin. Fry production amounted to 2.6 million in 1962 and 13.8 million in 1963. All of the fry were stocked in the major reservoirs of South Carolina except the Santee-Cooper Reservoir.

Several mined-out and flooded phosphate pits near a large population center in peninsular Florida have been acquired and put under management by the Florida Game and Fresh Water Fish Commission for public sport-fishing purposes. Costs of making these abandoned phosphate areas accessible to the public are discussed; fishing pressure and sportfishing success on renovated ponds are reported and compared; and the relationships of size and shape of the ponds to success in fishery management are noted.

One thousand seven hundred and forty-nine Spotted Bass were tagged in Allatoona Reservoir, Georgia, in the winter of 1961-62 and rewards were paid for return of the tags by sport fishermen. The nature of the Spotted Bass fishery and population density is described on the basis of these tag returns and creel census. Two hundred and sixty-two Largemouth Bass were tagged simultaneously and comparative data on the two species is given.

A vinyl tube is being used on the dorsal spine of bass, crappie, and bluegill. Indications are that this tag does not have the adverse effect on the fish that the dart tag or the spaghetti tag has. Loss of tags at the present time is high but work continues using different diameters of tubing and the addition of a glue.

Bussey Brake Reservoir is a 2,200-acre impoundment located in northeast Louisiana near Bastrop, Louisiana. This lake was stocked by the Louisiana Wild Life and Fisheries Commission in 1959. It was opened to public fishing on April 30, 1960. Creel data collected through April, 1963, are reported. Fishing pressure varied from 46,000 to 59,000 fisherman trips per year during this period. From 91 to 109 man-hours were spent per acre to catch 76 to 102 pounds of fish per acre. The success ratio varied from 1.74 to 2.29 fish per hour. The fish averaged 0.37 to 0.53 pounds. The average size of fish increased and the fishing success declined, but was high throughout the three-year period. With continued extensive usage· of the lake, harvest rates of the same general magnitude should be possible for several years.

Threadfin shad can be successfully maintained in aquaria for long periods on a diet of newly hatched brine shrimp. They quickly die at 5.0 and will survive the winter in a lake that does not go below 90C.

Eighteen species of fish including a reference species, were subjected to toxicity bioassay using petroleum refinery effluent as a toxicant. Twenty-four-hour and 96-hour median tolerance limits Were calculated using a straight-line graphical interpolation based on ten specimens per concentration with a replication. Collection, laboratory, and bioassay histories were recorded for each test species and a general suitability statement made for each. Twenty-four-hour and 96-hour adjusted resistances obtained by the “Preadjusted-Abbreviated Doolittle” method were subjected to analysis of variance and to a modification of Duncan's new five percent multiple range test. Six methods were employed to adjust the relative resistance for differences in tests. The tests were ranked according to results obtained by each adjustment from most to least resistant.

It is estimated that some 7500 square miles or 4,800,000 acres of estuarine area exist on the periphery of the Gulf of Mexico. Gulf commercial catches of fish and shel1fish in 1960 consisted of over 1 billion pounds of estuarine dependent species. The contribution of Gulf estuaries ~ward these catches amounted to approximately 230 pounds per acre. The evaluation of estuaries is discussed in terms of total production including other forms of organic matter. Beneficial and detrimental uses of shal1ow-water coastal areas are cited.

During 1963 a series of experiments was conducted to determine the effect of dynamite on fish populations. One set of these experiments consisted of placing various species of fish in cylindrical wire baskets which were suspended vertically in water ranging from six to 15 feet in depth. A dynamite charge, consisting of one stick of 60% ditching dynamite, was placed at a point 10 feet from the nearest line of baskets and was detonated. Nine experiments were conducted using this arrangement of baskets in various depths of water with the dynamite charges ranging in depth from 2.5 feet below the surface to one foot from the bottom. The results of these experiments indicated the effective killing range of the dynamite charge and the most desirable depth at which to set the charge. From these tests it was found that some fish were killed up to a distance of 50 feet from the charge and that the greatest number of kills occurred when the charge was placed 2.5 feet below the surface.

In a food-habits study of young largemouth bass at the National Fish Hatchery, Marion, Alabama, midges were found to comprise 80 to 90 percent of the total food volume in fish from 25 to 55 millimeters in length. Since midges were found to be such an abundant food item in the diet of these fish, attempts were made to increase the midge crop by providing additional surface area in the pond for attachment. It was found that ponds having a dominant blue-green algae bloom (Anacystis spp. and Anabaena spp.) produced more midges than ponds having a dominant green algae bloom (Oocystis spp., Chlarella spp., anti Coelustrum spp.). Black polyethylene sheets, lh-inch masonite board, and 14-inch cement-asbestos board, plus concrete and clay-tile building blocks were oriented in different positions in a pond to determine which material and position were most productive. The masonite board proved to produce the most midges. Polyethylene sheet was next most productive.

The prevalence of parasitic epidemics is dependant, to a large extent, upon the density of the host population. Through the application of recent research, up to 2,400 pounds of channel catfish can be produced per acre of water, thus placing their commercial culture on a basis comparable to production of other farm animals. Since fish are confined to a limited environment in ponds without flowing water, they are surrounded by their own metabolic wastes throughout the production period. Such an environment is ideal for the propagation and development of parasitic populations. The great majority of epidemics are caused by external protozoan and helminth parasites that are transferred by contact and have simple life cycles. The species causing epidemics in channel catfish production ponds in Alabama are presented in Table I.