Journal of the Southeastern Association of Fish and Wildlife Agencies

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.

Antimycin was applied to five fresh-water ponds at 3, 4, or 5 ppb, and to two salt-water ponds !lit 10 ppb. Undesirable fish, including four centrarchids and one cyprinid, were eliminated from four of five freshwater ponds. Undesirable fish, including a centrarchid and a livebearer, were eliminated from both salt-water ponds. Mosquitofish, Gambusia affinis, were killed in five ponds, but were eliminated in none. Channel catfish, Ictalurus punctatu8, that were in four ponds, were not killed. Antimycin showed real promise as a fish toxicant particularly for removing trash fish from catfish ponds. Antimycin, under the trade name fintrol, is registered as a fish toxicant by the Food and Drug Administration and by the U. S. Department of Agriculture. The retail cost to treat one acre-foot of water with 3 ppb antimycin was approximately $4.50.

The TLm for bluegill and redear sunfish was determined in the laboratory using standard bioassay procedure and water from two sources. A considerably larger concentration of antimycin was required to kill fish of the same size under field conditions. Probable reasons are discussed. Selective kills of bluegill and redear were attempted in the field under pH values ranging from 6.4 to 9.6. The antimycin concentration required under these various conditions is discussed. Total kills following selective kills showed size selectivity as well as species selectivity.

Twelve state-owned lakes in Oklahoma were surveyed in 1965 to obtain data on sport fishing and recreational use. The lakes were virtually unmanaged and ranged in size from 26 to 180 surface acres. This project was designed to provide a basis for future management. Data was calculated on an I.B.M. 7040 computer. Average harvest in pounds per acre ranged from 22 to 107, with fishing pressure ranging from 138 to 622 hours per acre. The catch consisted mainly of largemouth bass, crappie, channel catfish, bullheads, redear sunfish and bluegill sunfish. Most of the fishing effort was expended from April through October. Other recreational use consisted mainly of sight-seeing, camping and picnicking. This usage rivaled fishing in number of participants on most lakes.

Blue Mountain Dam, a flood control project on the Petit Jean River in west central Arkansas, was completed in 1947 impounding a 2,900 acre reservoir. The reservoir is relatively shallow, receives strong wind action and has a watershed to lake area ratio of over 100:1. Since four to five years after impoundment, the lake has been plagued with heavy concentrations of colloidal turbidity and a fish population dominated by non-foragable sizes of buffalo, carp, drum and gizzard shad. Combinations of fall-winter drawdowns, commercial fishing for nongame species, a selective shad kill and the planting of rye grass in the exposed lake bed produced beneficial results in reducing colloidal turbidity and improving the fish population. However, these results were shortlived. A continuation of these efforts in a more intensive and drastic form was initiated in June, 1965. The lake was dewatered to expose 1,500 to 2,000 acres of lake bed.

The retention rates of Atkins, dart, Petersen, spaghetti and strap tags were compared on largemouth bass, bluegill and Atlantic croaker. Antiseptics used in tagging operations were evaluated for their usefulness in promoting tag retention. Petersen and spaghetti tags were found to be the most suitable of the tags tested for bluegills in short-term studies of three months. Petersen, spaghetti and Atkins tags were found suitable for shortterm tagging (3% months) with largemouth bass. None of the tags were found suitable for long-term studies with the bass. Low retention rates were shown for all tags tested at the end of seven months. Almost no retention after a five-month period was realized from Atlantic croakers. Sterilizing tags and tagging instruments with 70 per cent isopropyl alcohol and a post-handling dip in malachite green solution were found to have no effect on growth or retention of tags on bluegills.

A small backpack fish shocker weighing 19 pounds. was develop,;d for use in sampling mountain trout streams on .the NatIOnal Forests. m the Southern Appalachians. Power .components mclude a small gasolme engine-generator combination and a step-up transformer. The completed backpack provides a choice of 125 volts, 300 volts, or 600 volts alternating current (AC). This unit is adaptable to two electrode systems. One, consisting of an aluminum dipnet and a telescoping radio antenna for the electrodes, proved most useful and versatile in the rough headwater streams sampled. With it, one man handles both the power unit and the electrodes. The other, a thirteen foot electric seine, required a larger crew but was useful in wide shallow streams. During the period April, 1966-July, 1967, over 100 stream fish population samples were taken in North Carolina, Virginia, and Georgia with this gear.

Commercial fish farming is the fastest growing industry in the field of agriculture in Arkansas. Due to its fast growth, allied industries have not kept pace. Part of the difficulty has been the lack of knowledge in the right places as this industry has developed. To collect statistics on this ballooning industry, a meeting between interested agencies was held at Stuttgart, Arkansas. At this meeting a questionnaire was developed with the idea of programming the information for IBM storage. The results of the questionnaire are discussed in the paper, the information received was expanded to cover the nonresponders. It is the express purpose of this paper to present an accurate estimate of the 1966 commercial fish production in the State of Arkansas. An industry as young as this one with a value of $9,165,000 is worth keeping tabs on.

The stomachs of 525 largemouth bass fry and fingerlings were examined and the food organisms identified to genus when possible. Length and width measurements were made on the food organisms to determine area and then the area was used as an index to volume. The most important food organisms were copepods, cladocerans, and midges. There was a size relationship between fish and food item with the larger fish taking a larger food item. Fish smaller than 15 millimeters in length ate copepods and cladocerans primarily while larger fish ate mostly midges. No cannibalism was detected in the fish examined.