Journal of the Southeastern Association of Fish and Wildlife Agencies

In order to make an estimate of the size of a population of animals at a given time by the Petersen method, use is made of a sample of the fraction of marked animals in the population. However, if some of the animals originally marked lose their marks and thus can not be identified in the sample, a Petersen type estimate will be biased, the magnitude of the bias depending upon the proportion of animals retaining their identity. If an estimate can be made of the animals which have retained their identity at a given time, it is possible to make corrections for this bias. This report presents formulas for estimating the number of marked animals which have retained their identity at a given time from multiple marked animals and shows their derivation, shows their application to the Petersen method, discusses the necessary conditions for them to apply, discusses the errors associated with such estimates and shows how confidence limits can be determined.

In its attempt to provide more and better fishing in the State, the Fisheries Section of the Alabama Department of Conservation initiated a program whereby fishery biologists would check all ponds before they were stocked with hatchery fish. Attempts were made to contact each pond owner, check the pond in his presence, and advise him of the proper methods of stocking and management which have resulted from fisheries research in Alabama. A total of 845 ponds were checked in 14 counties in east-central Alabama during the period of September 1955 through September 1959. Of the 845 ponds checked, 766 were approved and stocked while 79 were disapproved for various reasons. Balance checks were conducted in 114 of the approved ponds during the first year of fishing. These checks revealed that 81 ponds were in balance, 10 were crowded with bass, 20 were overpopulated with bluegills and 3 were unbalanced because of large populations of undesirable fish.

The effect of removing various amounts of bluegill and black bullhead catfish from a small lake on the remaining fishes were studied. Estimates of population size by mark and recapture, numbers of desirable size fish, condition indexes and age and growth rates reveal some improvement in certain species but it was concluded that removals alone may not always produce greatly improved fish populations.

Experiments to determine concentrations of toxaphene lethal to fishes in a variety of lake types and to discern selective fish-killing properties of the material were conducted. Concentrations ranging from 1 to 85 parts per billion were placed in fourteen bodies of water varying in size 200 from 0.5 to 2,100 acres. Vegetative cover varied from 0 to 95 percent, methyl orange alkalinity from 2 p.p.m. to 74 p.p.m., and hydrogen-ion concentrations from 5.1 to 9.5. Bottom types included gravel, sand, silt and mud. Differences in concentrations required to cause total kills of fish populations in treated lakes appeared to be related to bicarbonate alkalinities, bottom types, amounts of plankton, vegetation and the sizes of fish present.

During the summer and fall of 1957, experiments with dynamite were conducted to determine an effective method of removing concentrations of longnose gar, Lepisosteus osseus, from the large coastal streams of North Carolina. A “suspended series” of charges was the most effective method tested. Charge of 3 sticks of dynamite, suspended at depth of 8 to 10 feet produced the best lethal range. Selective blasting with this method provided efficent removal of longnose gar. During one day's operation, over 3% tons of gar were removed while killing 8.3 pounds of game fish.

Studies concerning the reproductive behavior, spawning temperatures, fecundity, period of egg formation, food habits, and lower lethal temperatures of the exotic cichlid, Tilapia nilotiea, were conducted in aquaria and in earthen ponds at Auburn University, during the period of April 1959 to June 1960. These studies suggest that the spawning behavior of T. nilotiea is typical of that of many cichlids and consists of schooling by the females, territorial establishment by the males, an intricate prespawning courtship, spawning, and parental care by the female. During this period of parental care, the eggs are carried in the buccal cavity until they hatch, and the fry remain there for about five days thereafter. T. nilotiea spawned in aquaria at a constant temperature of 740 F. Spawning occurred in ponds in late April when diurnal temperatures ranged from 70 0 to 84 ° F. The fecundity was found to vary considerably with the size of the brood fish and on a seasonal basis.

In the Tombigbee, Alabama, and Tensaw Rivers, 34 flathead catfish (Pylodictis olivaris) and 152 blue catfish (lctalurus furcutus) were collected by use of telephone-magneto shockers for stomach analysis. Transition in feeding habits from invertebrates to major use of fish occurred in flathead catfish at approximately 10 inches total length, and in blue catfish through the inch groups 8-13. Feeding habits in the three rivers are compared. Data on lengths of catfish and foods eaten are presented.

Striped bass, Roccus saxatilis, (Walbaum), occurs in all major river systems along the Florida Gulf Coast from the Suwannee River west to the Perdido. The only striped bass population in West Florida known to spawn successfully was in the Apalachicola River Drainage. The population level for the other rivers was too low to maintain a sport fishery. The Apalachicola River stock of striped bass is discussed in detail.

The minimum oxygen requirements of the following five species of fish were studied under quiescent conditions. Lebistes reticulatus (Peters); Gambusia affinis (Baird and Girard); Pimephales promelas (Rafinesques); Hybognathus placitus (Girard); and Notropis girardi (Hubbs and Ortenburger). Nitrogen gas was bubbled through the waters in the test vessels to remove the dissolved oxygen. The fish were tested under varied temperatures and at different levels of oxygen depletion. All specimens tested were able to live at oxygen tensions of 1.0 ppm. The reactions of the fish varies with (1) the spread of oxygen removal, and (2) the species.

The estimated total length of several species of forage fishes that spotted bass, Micropterus punctulatus, of given total lengths can swallow are given.

In some Georgia farm ponds a satisfactory phytoplankton growth is not produced following the application of normal amounts of fertilizer. Chemical investigations indicated a slightly acid condition and a low total hardness in these problem ponds. This condition was corrected by the addition of one ton per acre of agricultural lime or with varying amounts of hydrated lime added periodically. Phytoplankton production was definitely improved in over 100 Georgia farm ponds after the addition of lime. The average total hardness increase in these ponds, using agricultural lime at the rate of one ton per acre, was 15 ppm. Results lasted from 2-4 years. Hydrogen ion alone is not a satisfactory measure of the need for lime. Total hardness of the water was found to be the best and most reliable measure for lime supplements. For optimum fertilization results, the total hardness range should be 20 ppm or above.

Lake Hamilton is the middle of three lakes located in series on the Ouachita River in Southwestern Arkansas. Following the initial release of water through the penstocks from the upper newest lake, a subsurface current was detected in Lake Hamilton. During the summer of 1960, physical-chemical tests were made at nine stations along the channel to determine the extent of the current. Data collected showed the water remained oxygenated from the surface to the bottom. Cold water drawn from below the thermocline of the upper lake becomes oxygenated in the tailrace and slides under the warm upper stratum of water in the Lake Hamilton. Existing temperature ranges and sufficient dissolved oxygen levels, as were found in the channel, should sustain trout throughout the critical summer months.

Twelve species of fishes native to Oklahoma were each tested four times in a series of twenty bioassays, and the guppy was included in each bioassay as a reference. The 24-hour median tolerance limits (TLm's) were determined. The relative sensitivity of each species was established. In a 50/0 multiple range test, the species were grouped into the following six statistical populations: (1); (2); (3-5); (4-10); (5-12); and (6-13). In the following ranked list, numbers in parentheses (also the rank numbers of the species) indicate the statistical populations to which the species could belong with no significant difference, while, species not included in numbers in parentheses are significantly different from the population included. Fishes rank from most resistant to least resistant as: 1. Lebistes reticulatus (1); 2. Ictalurus melas (2); 3. Notemigonus crysoleucas (3-5); 4. Notropis lutrensis (3-5), (4-10); 5. Lepomis microlophus (3-5), (4-10), (5-12); 6.

Spot checking the stratification pattern existing within a power reservoir generally consists of a single series of oxygen and temperature determinations taken vertically at the point of maximum depth. The point of maximum depth ordinarily is found immediately upstream from the impounding structure. Data secured from a series of observations in the John H. Kerr Reservoir, Virginia, are presented which confirm Ellis' warning of 1936 that reservoir stratification in the immediate proximity of a power dam is very unstable and samples collected therefrom may yield entirely different results from samples taken at the same depth but beyond the limits of the adclaustral zone. When determining the stratification pattern within a power reservoir, a series of vertical profiles is indicated. These observations should be spaced along the inundated stream bed as closely as circumstances will permit.

A simple, portable, and effective apparatus for electrically stimulating macrobenthos is described as a material aid for rapid picking of bottom samples in the field. Experience has demonstrated that the use of electrical stimulation not only shortens the time required, but it also results in recovering many organisms that otherwise would be overlooked.

In April, 1958, creel censuses on the White River Arm of Bull Shoals Reservoir, Missouri, were altered to permit separate tabulations of data from anglers who fished exclusively in three areas of flooded standing timber. The combined acreage of the timbered areas is 6.3 acres, or 0.26 per cent of the entire creel census area (2,380 acres). During 1959, nearly 15 per cent of all anglers counted were timber fishermen. Fishing pressure in that year amounted to 5,138 hours per acre in timbered areas, as compared to 97 hours per acre in the remainder of the census area. The hook-and-line harvest in timbered areas was 3,054 pounds per acre, and in the remainder of the area was about 113 pounds per acre. In 29 months, 821 timber fishermen were interviewed, of whom 94.8 per cent were successful. Their rate of catch amounted to 1.25 fish per hour.

Flathead catfish fry were reared to fingerling size in troughs by starting them to feed on shrimp, and marine fish. Other foods that were subsequently eaten by fry and fingerlings included beef liver, spleen, eggyolk, cheese, canned dog food, canned salmon, and some dry cereal feed. The food was prepared by placing the meats in a blende, adding a small amount of water, and stirring until the food was “creamy” in texture. After approximately three weeks, the fish had increased in size so that they could consume the food passed through a food chopper. No feeding was attempted until the yolk sac had been absorbed and the fish exhibited feeding behavior. After two or three days, if not fed, the fry will not feed even though food is offered. The food was placed (with a pipette or by rubbing between fingers) in the water above the fish.

Albino (golden) and normal channel catfish were compared in feeding experiments during a 346-day period. There was no difference in rate of growth, but the percentage of survival was 94.2 for the normal catfish and 81.1 for the albinos. Fishing success was similar for the two.

Experiments to determine the forage species preference of largemouth black bass fingerlings and a few larger bass are described. Data on the amount of food consumed, rate of growth and food conversion are presented. Forage minnows included were goldfish, Carassius auratus (Linnaeus), fathead, Pimephales promelas (Rafinesque) and bluegill, Lepomis macrochirus (Rafinesque). While there was' evidence of considerable individual variation in the species of forage minnow preferred, the bass in the experiments preferred fatheads more frequently than the other species, goldfish were second choice and bluegills were last. The degree of preference between bluegills and goldfish did not appear to be great for the limited number of bass included. Food conversion was best on a fathead or bluegill diet.