A Decade of Changes for Virginia Freshwater Aquaculture (1993-2003)

Aquaculture surveys were designed and initiated along with the writing of the State Aquaculture Plan during 1993 to 1995. The first Virginia Aquaculture Survey, conducted for the production year 1993, established the status of both freshwater and marine commercial industries. Subsequent surveys were conducted to trace industry developments relevant to production aspects and economic impacts. Survey data from Virginia Agricultural Statistics Service Reports for 1993, 1995, 1997, and 2003 summarize a decade of Virginia freshwater aquaculture information. Significant changes in sales among the principal aquaculture species occurred over the 10-year period. The 1993 freshwater aquaculture value of $2.8 million increased to$6.0 million in 2003; however, the increase was due to $4.2 million in tilapia sales. Thus, the balance of$1.8 million is actually a decrease by $1 million for 2003 sales when compared to 1993. Losses in trout sales account for the$1 million decrease in 2003. Catfish and hybrid striped bass production and sales remained low and declined during the 10-year period

Potential of Utilizing Scrap Processed Cheese as a Major Ration Component for Channel Catfish

Three cages (0.9 m³) were stocked with 200 channel catfish, Ictalurus punctatus Rafinesque, fingerlings (73.7 g avg.) in a 1.5 hectare pond. Two cheese rations were formulated and fed to the catfish; the first consisting of cheese, oil, and vitamin C (C + VC)and the second consisting of cheese, cottonseed meal, oil, trace minerals, and vitamins (CC + VM). A commercial trout ration (TC) was fed as a control. High mortalities occurred in the C + VC diet, thus resulting in premature removal of that cage from the study (after 86 days). A sample of 50 fish from the two remaining cages, along with harvest data from the C + VC diet, revealed a 45.6% difference in average fish weight between the C + VC and CC + VM diets, a 63.5% difference between the C + VC diet and TC ration, and 32.9% difference between the CC + VM diet and TC ration. Final harvest of CC + VM and TC cages was completed after 134 days. Comparisons revealed that a 38.3% difference in average fish weight existed between these two diets. Statistical analysis of data indicated that fish fed the CC + VM diet had a significantly lower percentage dress-out weight and a significantly higher amount of mesenteric fat. This experiment does suggest that cheese scraps, when properly balanced with other essential ingredients, may be utilized as a major component of catfish rations

Evaluation of a Full-Fat Soybean Ration for Channel Catfish Production in Cages

An experimental ration consisting of 50% full-fat soybeans, heated 170°C, was compared to a commercial trout chow in a 120-day feeding trial using two stocks of channel catfish, Ictalurus punctatus Rafinesque. Catfish were reared in 0.9 m³ floating cages, with 200 fish per cage, anchored in a 1.5 hectare farm pond. A Central Arkansas stock significantly outperformed a Southeast Arkansas stock for comparisons of net production and food conversion efficiency (FCE), with 92% greater production and 41% better FCE, respectively. Survival was 90% or greater for all fish. There was no significant difference in dress-out weight between the stocks. However, the catfish fed the trout ration had significantly lower amounts of body fat. The commercial trout chow overall was significantly better for fish production than the full-fat soybean ration. Production with trout chow was 84% greater than with the full-fat soybean ration. Food conversion efficiency was nearly 41% better with the trout ration, while percent body fat was 11% less. There were no differences in percent survival and percent dress-out weight between the rations. The Central Arkansas stock fed the commercial trout ration had the lowest production cost of 0.47¢ per 0.45 kg live weight, while the Southeastern stock had a higher production cost with either feed

Attraction of Aerial Insects as a Fish Food Supplement

Insect populations over a 1.2 hectare southeast Arkansas livestock pond were sampled to consider the possibility of their use as a fish food supplement. A commercial insect attraction unit was suspended above the pond, and attracted insects were collected. Insect populations were sampled 3-4 nights each month, January-December, 1976. Insects collected were identified and analyses were performed to determine nutritional composition and pesticide content. Insect samples were variable, however, 62% of the insects identified were in the Order Diptera and 97% of these were in the Family Chironomidae. Nutritional analyses revealed insects were more than 60% crude protein. Pesticide analysis indicated 0.98 ppm toxaphene was present in the insect

Precision Doppler Shift Measurements with a Frequency Comb Calibrated Laser Heterodyne Radiometer

We report precision atmospheric spectroscopy of $CO_2$ using a laser heterodyne radiometer (LHR) calibrated with an optical frequency comb. Using the comb-calibrated LHR, we record spectra of atmospheric $CO_2$ near 1572.33 nm with a spectral resolution of 200 MHz using sunlight as a light source. The measured $CO_2$ spectra exhibit frequency shifts by approximately 11 MHz over the course of the five-hour measurement, and we show that these shifts are caused by Doppler effects due to wind along the spectrometer line of sight. The measured frequency shifts are in excellent agreement with an atmospheric model, and we show that our measurements track the wind-induced Doppler shifts with a relative frequency precision of 100 kHz (15 cm/s), equivalent to a fractional precision of a few parts in $10^{10}$. These results demonstrate that frequency-comb-calibrated LHR enables precision velocimetry that can be of use in applications ranging from climate science to astronomy.Comment: 4 pages, 3 figure

Mosquitofish, Gambusia affinis (Baird and Girard) Production in Extensive Polyculture System

During 1976, mosquitofish, Gambusia affinis Baird and Girard, were reared in combination with food and game fishes in 0.1 ha culture ponds at the University of Arkansas at Pine Bluff fisheries research facility. Mosquitofish production was 218 kg/ha, with 1683 fish per kilogram, in ponds that were also stocked with channel catfish, Ictalurus punctatus Rafinesque, bigmouth buffalo, Ictiobus cyprinellus Valenciennes, grass carp, Ctenopharyngodon idella Valenciennes, and silver carp, Hypophthalmichthys molitrix Valenciennes. In another similar stocked pond, hybrid sunfish fingerlings depressed mosquitofish yield by 79%. No mosquitofish production was obtained in ponds stocked with 250 largemouth bass, Xficropterus salmoides Lacepede, fry per hectare, although fathead minnows, Pimephales promelas Rafinesque, were added to buffer mosquitofish predation. Total fish yields ranged from 414 to 670 kg/ha for the polyculture systems investigated