R. Oneal Smitherman

Genotype-environment interactions for growth of blue, channel and hybrid catfish in ponds and cages at varying densities

Channel catfish, Ictalurus punctatus; blue catfish, I. furcatus; and hybrid channel ♀×blue♂ catfish fry were grown in ponds at densities of 7410/ha–2 245 000/ha. Channel catfish fingerlings and hybrid fingerlings were grown in ponds at densities of 7410/ha–22 230/ha, or 7410/ha with the addition of 1000 or 2000 kg/ha of co-stocked larger fish and in cages at 275/m3. Genotype-environment interactions for growth rate occurred (P<0.05) between hybrid catfish and channel catfish fry and between blue catfish and channel catfish fry stocked at varying densities. Channel catfish fry grew faster (P<0.05) than hybrid fry at low densities, but hybrid catfish fry grew faster than channel catfish fry at higher densities. The relative growth advantage of channel catfish fry over blue catfish fry increased with density. The increased growth rate of hybrid catfish fry compared to channel catfish fry at high densities was observed in both communal and separate experiments. Hybrid catfish fingerlings grew faster to market-size than channel catfish fingerlings at all densities in ponds. Their relative advantage to channel catfish increased with density and the addition of larger competing fish in the ponds. The hybrid was also superior to channel catfish in both communal and separate high density experiments when grown from fingerlings to marketsize. Genotype-environment interactions occurred for growth rates in cages or ponds. Hybrid catfish grew faster (P<0.01) than channel catfish in ponds, but slower (P<0.01) than channel catfish in cages.

Response to selection and realized heritability for body weight in three strains of channel catfish, Ictalurus punctatus, grown in earthen ponds

Abstract Response to selection and realized heritability for body weight were determined for three strains of channel catfish grown in earthen ponds at 7500/ha. The strains — Rio Grande (Texas), Marion (Alabama), and Kansas (Kansas) — had different histories of domestication, 10 years, 20 years, and 60 years, respectively. At a harvest weight of approximately 500 g, the largest 10% of each population was selected. The growth performance of progeny from selected fish was compared to that of progeny from randomly chosen fish. Significant responses to selection (P 0.05) from Rio Grande or Marion. Responses for male and female body weights were the same in Marion (P > 0.05) but response by Kansas males was higher than that for Kansas females (P 0.05).

Lack of Response by Tilapia nilotica to Mass Selection for Rapid Early Growth

Abstract Mass selection for rapid and slow early growth was applied for one generation to 58-d-old Nile tilapia Tilapia nilotica (Ivory Coast strain). Realized heritability (±SE) for rapid growth was –0.10 ± 0.02, and mean body weight of progeny was not different (P > 0.05) from that of control fish. This confirms an earlier prediction from half-sib analysis of the same stock that selection for rapid growth would be ineffective for these fish (half-sib heritabilities were 0.04 ± 0.14 at age 45 d and 0.04 ± 0.06 at age 90 d). In contrast, selection for slow early growth resulted in realized heritability of 0.36 ± 0.08, and mean body weight of progeny was less than that of control fish (P < 0.05). Our study indicated that an upper limit to growth enhancement by selection exists in this stock of T. nilotica, probably due to a small founder stock, subsequent reductions in effective breeding numbers, and 8 years of domestication. We conclude that half-sib analysis can be an efficient means for estimating the e...

Response to three generations of selection for increased body weight in channel catfish, Ictalurus punctatus, grown in earthen ponds

Abstract Selection response for body weight at marketable size was measured for channel catfish, Ictalurus punctatus, grown in earthen ponds at 7500 fish/ha. Three generations of mass selection for increased body weight in Kansas and Marion strains of channel catfish increased body weight from 453 to 583 g or 29%, and from 530 to 642 g or 21%, respectively, with cumulative realized heritabilities of 0.17±0.016 and 0.19±0.012, respectively. Realized heritabilities for the third generation alone were 0.16±0.016 and 0.23±0.015 for Kansas and Marion strains, respectively. The results indicate that body weight can be significantly increased via mass selection in channel catfish, which should result in increased production and profitability in the catfish farming industry.

Review of catfish breeding research 1969–1981 at Auburn University

Abstract Catfish (Ictaluridae) breeding experiments conducted at Auburn University 1969–1981 are summarized. Strain comparisons and three major breeding programs (mass selection, intraspecific crossbreeding, and interspecific hybridization) were used to improve growth, survival, reproductive performance, disease resistance, seinability, vulnerability to angling, carcass yield, and tolerance to low dissolved oxygen. Different test environments (aquaria, cages, and ponds) were evaluated. Marking systems for fish identification were compared. Communal stocking and multiple-rearing were tested. Genetic and environmental components of variation were determined.

Comparison of strains, crossbreeds and hybrids of channel catfish for vulnerability to angling

Abstract Fee-fishing is a major outlet for commercially grown catfish in the United States. Success at these operations is partially dependent upon the vulnerability of catfish to angling. Genetic differences in catchability have been previously demonstrated. The interspecific hybrid produced by mating a channel catfish, Ictalurus punctatus, female with a blue catfish, I. furcatus, male was more catchable than its parent species. However, the effect of parental strain on heterosis was not evaluated. In the present experiment, several strains of channel catfish were compared for vulnerability to angling and strain differences were evident (P

Food Habits of the White Amur Stocked in Ponds Alone and in Combination with other Species

that biological methods be used for controlling undesirable aquatic plants in both artificial impoundments and natural waters, since many of our existing chemical nntrol methods are potentially hazardous to the ecological balance of a pond, lake, or river, as well as to man himself. A number of organisms exist which will effectively control or eliminate certain aquatic plants. Several fish species have shown promise fs weed control agents, one of these being the white amur (Ctenopharjngodonidellua Va, lenciennes) also known as grass carp (Avault, Smitherman, and Shell, 1968). This fish has been in the United States for a decade, but is an exotic species indigenous to large rivers in China. One of the major reasons that white amur are not being widely used in this country is the fear that they may become established in our natural waters, as did the common carp, and compete with native fish for food organisms. Hora and Pillky (1962) reported that white amur do not spawn in ponds--they spawn in large rivers. If this is so, and it seems to be, it is possible that they can be used in ponds which are not connected to natural waters. Hora and Pillay (1962) classified white amur as an omnivore, and stated that it has a

Relative growth, survival and harvestability of bighead carp, silver carp, and their reciprocal hybrids

Abstract Growth and survival in the primary rearing phase (42 days) for bighead carp, silver carp, bighead × silver carp (BHC × SC), and silver × bighead carp (SC × BHC) in ponds and concrete tanks stocked at 370 500 fry/ha were studied. Mean survival for fishes in ponds was 93%, that in tanks was 73%. Yields among all fishes averaged 338 kg/ha. The growth rates of fishes in ponds were similar; in tanks, silver carp grew faster than the bighead carp. Growth, survival, and harvestability by seine during the secondary rearing phase (60-day duration) for the same groups of fish were studied. Fingerlings (0.9 g mean weight) were stocked in earthen ponds at 49 400 fish/ha and 98 800 fish/ha. Mean survival of fishes at low stocking rate was 77%, similar to that (71%) for the high stocking rate. Fish yields were similar at the low stocking rate. At the high rate, the BHC × SC yield (846 kg/ha) was greater than the SC × BHC yield (582 kg/ha). The BHC × SC and SC × BHC had greater mean weights at low stocking rate than at high stocking rate. The mean weights for bighead carp were similar at both rates. Bighead carp and the reciprocal hybrids were more easily harvested by seine than silver carp.

Hybridization and Biochemical Genetics of Black and White Crappies in the Southeastern USA

Abstract Populations of black crappie Pomoxis nigromaculatus and white crappie P. annularis in Alabama, Arkansas, and Tennessee were examined for isozyme variation. Twelve diagnostic loci distinguished these two species. Both species exhibited low levels of genetic variation. Percentages of loci polymorphic in populations of black and white crappies were 0–4.7% and 0–11.6%, respectively. Mean heterozygosities were 0.000–0.008 and 0.000–0.012 for black and white crappie populations, respectively. Although extremely low levels of genetic variation were detected within or among white or black crappie populations when only nonhybrid individuals were considered, there were some distinct differences among populations within each species. Populations in Tennessee tended to have a greater number of unique, low-frequency, variant alleles than other crappie populations. Black crappies possessing the blacknose trait had allele frequencies similar to those of black crappies with normal coloration. Natural hybridizati...

Reproductive Performances of Crossbred and Pure-Strain Channel Catfish Brood Stocks

Abstract Pure-strain and interstrain (crossbred) channel catfish Ictalurus punctatus were compared for spawning day, spawning rate (percent of replicate pairs that spawned), fecundity, egg size and hatchability, and survival of offspring. Crossbred fish usually spawned earlier (P < 0.05) than pure-strain channel catfish. As 3-year-olds, crossbred fish had higher spawning rates and fecundity than purebred fish, and their output of juveniles (number surviving 45 days in ponds, per kilogram of female parent) was greater. As 4-year-olds, pure-strain fish improved their performances, and crossbreds lost most of their relative advantages. Brood stock derived from crosses of four strains spawned earlier than those from two-strain F2 crosses, but their surviving offspring were no more numerous. The main value of cross-strain breeding is to produce channel catfish that mature earlier in life and spawn sooner in the season than purebreds. Received July 16, 1982 Accepted March 4, 1983