Journal of the Southeastern Association of Fish and Wildlife Agencies

During the spring of 1967, 240,000 striped bass and striped bass X white bass hybrid fry were stocked in four one-acre dirt ponds. Each pond received 30,000 striped bass and 30,000 hybrids. At the end of a 71-day period, approximately 23,187 were harvested in three ponds, 12.88 percent of ,the original number. A total kill occurred in the fourth pond one week prior to harvest. Results indicate the hybrid having faster growth and higher survival rates.

Commercial catch statistics for brown shrimp (Penaeus aztecus Ives) from a restricted area along the Texas coast were examined by using the virtual population technique. The sum of all catches from a single year class was used as a minimum estimate of population size at the time of recruitment. The conversion of catches from pounds to numbers also made possible maximum estimates of the exploitation rate for all periods after recruitment. Monthly catches of shrimp of each size group were compared for the years 1961-66, and weights were converted to value by using the mean price per pound for each size group for the period. Comparisons of the percentage of a year class harvested at each size with the percentage of the gross value contributed by each size group may aid in making decisions concerning the management of shrimp stocks.

Analog computation and simulation involves the use of an electronic computer in which scaled voltages represent physical variables. This computer solves differential equations to simulate time related systems. Simulation of Von Bertalanffy's equation representing growth in length or weight is a simple procedure. Change of constant values enables a rapid adaptation and fit to a given set of growth data. A check on age analysis by using length-weight plots may be possible with this computer. An example of its use in analysis of striped bass growth is given.

Pink or spotted (Penaeus duorarum) , brown (P. aztecus) , and white (P. setiferus) shrimp, marked with biological stains and fluorescent pigments, were released in nursery areas tributary to the Core Sound and Lower Cape Fear River estuaries in Nor·th Carolina to obtain information concerning population dynamics including movement and migration patterns. A combined total of 26,989 pink, brown, and white shrimp was marked and released from April to October, 1966. Of these, 1,671 or 6.2% were returned. The combined average interval between release and recapture was 17.5 days, and the average distance traveled was 0.5 miles per day. Data indicated that size distribution "levels of equilibrium" were reached in individual nursery areas, whereby the size frequency modes increased to characteristic levels and subsequently remained at these levels during the study of each species. With few exceptions, all "inside" movement was toward waters of higher salinity.

The voluminous amounts of biological information collected for the Mississippi Estuarine Inventory required the development of a system for the automatrc processing of this data. The prime requirement of such a system was preparing a taxonomic code that could be easily updated and efficiently handled by EDP equipment. A modified version of the phylogenetic taxonomic structure was used to reduce the extent of the code and make optimum use of computer time. By the use of several search algorithms, computer memory requirements were substantially reduced. The utilization of the coded input to present an output with scientific names rather than code eliminated the undesirable need for double reference. The necessity for the biologist to be involved directly with the processing is eliminated, thus freeing him to devote his talents to the comprehensive interpretation of the results.

The growth of the Pacific herring (Clupea pallasii), lake sturgeon (Acipenser fulvescens) and white sturgeon (Acipenser transmontanous) is analyzed by the application of Parker-Larkin and Von Bertalanffy equations. The physiological significance of the parameters of the ,two equations is discussed.

During the process of a biological sampling program for Mississippi's Estuarine Inventory, data on the spawning season and influx of young were compiled for the two species of silversides found in Mississippi estuarine waters, Menidia beryllina (Cope) and Membras martinica (Valenciennes). Silversides taken from collections made with seines, beam trawls, plankton nets and dip nets were measured and the condition of the gonads noted. These data, when combined with associated field observations, first revealed ripe male and female Menidia beryllina (68 mm to 98 mm) in late March (water temperature 23.9°C) and Membras martinica (66 mm to 79 mm) in early April. M. beryllina in spawning condition were collected in salinities ranging from 3.6'/00 to 31.5%0 and water temperatures ranging from 23.9°C to 32.7·C throughout the spring and summer months. Spawning M. martinica were collected in salinities from 9.4 °/00 to 31.1·00 and in water temperatures from 21.2·C to 30.7°C.

Severe reduction in number of river redhorse, Moxostoma carinatum (Cope), has occurred in Alabama and the southeast during recent years. The Cahaba River is one of the last strongholds for this species in Alabama. Electrical shocking equipment was utilized during this study. Two hundred eighty-six adult river redhorse were captured, tagged, and returned to the Cahaba River. Redhorse were observed spawning on gravel shoals during April, 1966 and April, 1967 with water temperatures ranging from nOF. to 76° F. Egg counts made on river redhorse ranging in size from 17.9 inches to 22.1 inches total length revealed a range from 6,078 to 23,085 eggs per individual, respectively. Pond-reared river redhorse exhibited slower growth than those in natural habitats. River redhorse fed heavily on the Asiatic clam, Corbicula 8pp. Present utilization of the river redhorse as a sport fish is light.

Stomach contents were examined from 1,288 longear sunfish, 827 green sunfish, 1,099 bluegill, 246 largemouth bass, 144 smallmouthbass, and 304 spotted bass collected from shoreline areas of a reservoir in the process of filling and from one 15 years old, during and following bass spawning, 3 May-25 June, 1965. Young-of~the-year and bass 8.0 inches or more in length are not included. This study suggests that in the new reservoir the food supply was ample in relation to the centrarchid population demand. In the older reservoir the opposite was true, resulting in more efficient utiliz3ltion of all available foods, including appreciable quantities of bass eggs and young. However, availability was influenced to a marked extent by size of predators and prey as well as abundance. The result was food "skimming," whereby the larger fish usurped the tendipedids and large cladocerans, leaving only smaller prey available for newly hatched largemouth young.

The spawning behavior, age and growth and food habits of white bass, Roccus chrysops (Rafinesque), were studied in Center Hill Reservoir, Tennessee, from October, 1965 until March, 1967. White bass began to move toward the headwaters in late February and early March when water temperatures rose above 45° F. Spawning started in mid-March at a water temperature of 53° F. and appeared to stop if water temperature dropped below 53° F. The duration of the spawning season was one and one-half to two months. The growth rate of white bass was more rapid than in other waters. The maximum age of white bass in Center Hill Reservoir is eight years. The primary forage species for adu1t white bass were shad, Dorosoma spp.

Fingerling spotted gar, Lepisosteus oculatus (Winchell), stocked at rates of 100 and 148 per acre into four Alabama ponds containing bluegills, Lepomis macrochirus, and fathead minnows, Pimephales promelas, failed to control crowding of bluegill within a 22-month experiment. Plastic-lined pools stocked with adult gar and equal numbers of bluegills, golden shiners, Notemigonus crysoleucas, largemouth bass, Micropterus salmoides, and white catfish, Ictalurus catus, showed the least reduction in numbers of bluegill, followed by golden shiners, white catfish, and largemouth bass. An emaciated condition that developed in the largemouth bass may have contributed to their vulnerability.

The position of Bull Shoals Lake as the lower lake in a chain of four large reservoirs located on the main stem of the White River in Arkansas and Missouri is described. During the three years of 1961, 1962, and 1963, physical-chemical determinations were made at three sampling stations situated along the channel of the lake. Trout requirements with respect to tempera,ture and dissolved oxygen as reported by other authors in the Southeastern United States are reviewed. Data collected showed that trout could survive year 'round in the vicinity of all stations. Concurrent experimental stocking of tagged rainbow trout, Salmo gairdneir** (Richardson), and tag returns during this study are discussed.

Physico-chemical factors, plankton, benthic macroinvertebrates, and fishes occurring in cold tailwaters below Beaver, Bull Shoals, and Norfork dams in northern Arkansas, were sampled regularly from July, 1965, through December, 1966. Physico-chemical conditions were similar in the three tailwaters throughout the study. The older tailwaters below Bull Shoals and Norfork dams were more productive than the Beaver tailwater in both phytoplankton and zooplankton. The greatest number of genera of plankton occurred in the Beaver tailwater, and the Bull Shoals tailwater had the least number. The majority of the benthic macroinvertebrates was comprised of only a few taxa. Samples from the Norfork tailwater contained more organisms and a higher average wet weight per square foot than did samples from the other two localities.

In Louisiana, the yo-yo fishing method has been a controversial fishing method. The yo-yo is an automatic spring loaded device equipped with a hook and when triggered by a fish will automatically set the hook and play the fish. During this project, 9,203 yo-yos were fished. The average success was 0.161 fish per effort. Approximately 21% of the yo-yos fished were tripped but caught no fish. There was little difference between day and night fishing successes. The devices were fished most efficiently during February and March. Best depths for fishing were between three and four feet. The use of sinkers greatly reduces the effectiveness of yo-yos. Based upon data gathered during this project, the yo-yo is not so efficient as popularly imagined to be and, there is no evidence that it should not be a legal fishing device.

Three lots of 6-day-old to IPh-month-old channel catfish from a common initial source but reared under different thermal conditions were utilized to investigate several heat-tolerance relationships. During the experimental period the fish were held in constant-temperature tanks and samples of fish were subjected to a range of sub-lethal and lethal temperatures in test baths. The results were studied by plotting time to death of individual fish and means of test samples on semi-log paper, probability paper in some instances, and subjecting pertinent data to statistical analysis. Fish acclimated to 26.0, 30.0, and 34.0C had upper lethal temperatures of approximately 36.6, 37.3, and 37.8C respectively. Differences in resistance times were related to age but not to size.

The average selected temperature of a sample of Gambusia affinis previously acclimated to 20°C decreased from 28-29°C to about 27"C after the fish had lived in a temperature-gradient tank for one month. The final thermal distribution of the fish varied with sex and developmental stage. Males selected lower temperatures than did adult females. The young fish, although more scattered than the adults, occurred mostly at temperatures higher than those selected by the adults. These results may indicate temperature separation of young and adult fish in nature which would reduce intraspecific predation and competition. Heat resistance of adult females taken from the 26.2°C-compartment of the temperature" gradient tank was higher than the resistance of 28.0°C acclimated fish. The temperature-gradient females either had attained a high acclimation level by temporarily venturing above 28.0°C or had accumulated high resistance by living at varying temperatures below 28.0°C.

A flowing-water respirometer was used to measure oxygen consumption of five species of estuarine fish: pinfish, Lagodon rhomboides; black sea bass, Centropristes striutus; Atlantic croaker, Micropogon undulatus; oyster toadfish, Opsanus tau; and mummichog, Fundulus heteroclitus. The relation between the amount of oxygen consumed and body size, in general, may be expressed by the formula Q = a Weightk, where a and k are constants derived from experimental data for a species. Some investigators have stated that k values do not vary significantly among species of fish. In my investigations the value of k did vary significantly between certain species. The values obtained for k are given and the methods used to measure respiration rates are discussed.

Salinity tolerance was compared between an inland population of red swamp crawfish, Procambarus clarki, from Baton Rouge, Louisiana, and a coastal marsh population from Grand Chenier, Louisiana. Newly hatched crawfish from each population were killed in less than one week in salinities of 15, 20 and 30 ppt. Crawfish, 30 mm in total length, withstood salinities up to 20 ppt, but died in 30 ppt in two to three days. Crawfish, 40 to 120 mm in total length, showed no significant mortality after one week in salinities up to 30 ppt. Thirty-millimeter crawfish exposed to salinities of 0, 10, 20 and 30 ppt for four weeks grew very little when fed fresh fish flesh, tropical fish food pellets, and Oedogonium sp. All 30-mm crawfish in 30 ppt died. Growth varied inversely with salinity. Forty- to fifty-mm crawfish held in 0, 10, and 20 ppt salinity for four weeks had average increases in weight of 4.4, 13.5 and 4.9%, respectively.

A survey on fish population was made in the upper Patuxent River, situated between the metropolitan centers of Washington, D. C. and Baltimore, Maryland, in the summer of 1966. This stream has received effluents of eight secondary domestic sewage treatment plants. Data obtained by two series of fish collections with a 10-foot-and-one-fourthinch mesh seine during June 17-July 14 and August 5-24 were compared with water quality data (dissolved oxygen, conductivity, and pH). The effects of sewage effluent on the fish species diversity and fish abundance in ,this stream were evaluated. Results of this study indicate that chlorinated sewage effluent reduced species diversity and fish abundance immediately below the seven effluent outfalls where dissolved oxygen remained at 4.2-10.6 ppm and pH value was 6.9-8.9 (above the limit of fish tolerance).

A study was conducted with blue and channel catfish to determine the effect of salinity upon distribution in a tidal bayou complex on Rockefeller Refuge, Grand Chenier, Louisiana. Stations were spaced at locations from the Gulf of Mexico to Grand Lake, a large freshwater body of water which is apparently quite productive of blue and channel catfish. Collections were made primarily with an otter trawl towed for 10-minute intervals at each sampling station. Hoop nets, wire traps, trammel nets, trot lines and rotenone were used to verify trawling results. Distributional data indicated that a 2:1 ratio existed between blue and channel catfish and that they are more abundant in waters with average salinities of 3.7 and 1.7 ppt, respectively. However, both species were collected from waters with salinities ranging up to 11.4 ppt.

The discreet utilization of Arkansas' expansiTe hatchery system has become an integral tool of the management staff of the fisheries division as related to the manipulation of a given fish population in a desired direction. As attempts at population manipulation through mass stocking of fingerling fish within existing populations became more or less universally accepted as being ineffective and incongruent with sound management principles, hatchery production, particularly of channel catfish, was slanted toward rearing of larger and older fish which would not only be less susceptible to predation, but would also create an immediate fishery where stocked.

Some effects of supplemental feed and fertilizer upon production of red swamp crawfish, Procambarus clarki, were measured during a five-month period at Baton Rouge, Louisiana. The tests, in vinyl-lined pools and earthen ponds, also evaluated stocking rates of 10,000 and 20,000 young per acre, effect of artificial cover on survival of young, and necessity of soil as substrate in crawfish production. The influence of feed, fertilizer, and soil on total hardness of well water was studied. The relationhip of total hardness of water to survival and growth of young crawfish was observed. Survival of crawfish in pools with soil was: fed, 65 percent; fertilized, 56 percent; control, 78 percent. In pools with no soil, survival was: fed, 0 percent; fertilized, 32 percent; control, 0 percent. Survival in pools was apparently not affected by increasing the stocking rate from 10,000 to 20,000 per acre, or by adding artificial cover.