Geology topics
H. L. Kincaid
Publications and source records attributed to H. L. Kincaid.
Causes and importance of genetic differences between groups of test fish
No abstract available at this time
Development of standard reference lines of rainbow trout
Explore the source record for details and available documents.
Three generations of selection for growth rate in fall-spawning rainbow trout
A selection program to improve the growth rate of rainbow trout (Salmo gairdneri) was begun in 1967 with random samples of fall‐spawning fish from the Manchester and Wytheville National Fish Hatcheries. All matings were made as one male to one female, and selection was based on family mean fish weight of the progeny at 147 days post‐fertilization. The selected families in each year class were mated in all combinations at 2 years of age (age II) and 3 years of age (age III). Selection was applied only to the age II progeny. A control group was established in 1971 from the base population and carried through the remaining portion of the study. All families were reared under standardized rearing conditions. During the three cycles of selection studied, mean 147‐day weight of progeny from age II parents increased from 2.02 g in the first generation to 5.28 g in the fourth generation, a gain of 161%. Of the 3.26‐g total gain during the study, net genetic gain in weight from selection was 0.98 g or 30.1%. The rest of the gain (69.9%) resulted from improved rearing conditions. Gains in percentage hatch and percentage fry survival to 147 days were not significant. Differences in the performance of progeny from the age III parents, as compared to that of progeny of age II parents from 1970 to 1974 showed an advantage for the age III parents in all three traits; 6.4% for percentage hatch, 25.0% for percent fry survival, and 22.3% for 147‐day weight.
Rotational line crossing: An approach to the reduction of inbreeding accumulation in trout brood stocks
A system is presented for maintaining trout brood stocks for long periods with levels of inbreeding accumulation lower than that experienced in random mating populations of equal size. The system requires the formation of three or more distinct breeding lines. Brood stock generations are advanced by a systematic mating scheme in which females of each line are mated to males of a different line. Eggs for hatchery production may be obtained from matings either within a single line or between lines. An opportunity for improving the breeding population is provided through selection of individual fish to be used in the production of the next brood stock generation. The requirement for increased handling of brood stock is not considered to be serious.
Inbreeding in rainbow trout (Salmo gairdneri)
Effects of inbreeding on rainbow trout ( Salmo gairdneri ) were evaluated by a comparison of differences between inbred and outbred half-sib families reared as contemporaries during the 1st yr of life. Attention was focused on two levels of inbreeding expressed as inbreeding coefficients: F = 0.25, one generation of brother–sister matings, and F = 0.375, two generations of brother–sister matings. Although inbreeding at the F = 0.25 level in fall-spawning populations had no effect on egg hatchability, it significantly increased the frequency of crippled fry by 37.6% and significantly decreased feed conversion efficiency (5.6%), fry survival to 147 days (14.6%), and growth rate to 147 days (6%) and 364 days (23.2%). Effects of inbreeding at F = 0.375 were more pronounced; significant differences included increased frequency of crippled fry (191.5%) and decreased feed conversion efficiency (14.9%), fry survival to 147 days (29.7%), and growth rate to 147 day s (13.4%) and 364 days (33.5%). Application of the total effects of inbreeding on the number of fish remaining and the weight of fish remaining in a production lot at 1 yr of age indicated losses of 17.4 and 36.6% after one generation (F = 0.25) and 47.9 and 65.4% after two generations (F = 0.375) of brother–sister mating. Similar studies on a spring-spawning population produced similar results. General breeding methods that minimize the rate of inbreeding accumulation are discussed.
Effects of inbreeding on rainbow trout populations
An approach for measuring inbreeding depression on the basis of differences between inbred and outbred half‐sib family groups is described. Using this method, estimates of inbreeding depression in populations of rainbow trout (Salmo gairdneri) following one generation of brother‐sister mating was calculated for three production traits–percent egg hatchability, percent fry survival from swim‐up to 150 days, and weight at 150 days. The inbreeding depression estimates obtained from male and female half‐sib families were 1.7 and 4.4% for percent egg hatchability, 22.2 and 16.1% for percent fry survival, and 12.0 and 9.8% for weight at 150 days, respectively. Estimates for fry survival and weight at 150 days were significant at P < 0.01 while egg hatchability estimates were nonsignificant. Following one generation of full‐sib mating, the calculated effect of inbreeding on the number of live fish and total weight of fish at 150 days of age showed a reduction of 16.1 and 24.4% in female families and 22.1 and 31.4% in male families, respectively. The difference between inbreeding depression estimates derived from male and female half‐sib groups provide a measure of the maternal influence. Generalized trends of increasing depression with increasing levels of inbreeding from F = 0.125 to F = 0.50 were significant for weight at all ages from 77 to 150 days, but were nonsignificant for percent hatchability or percent fry survival. Inbreeding depression estimates for weight are considered to be minimum estimates because higher mortality rates in the inbred families resulted in lower fish density during the rearing period and, therefore, compensatory growth which reduced the weight difference between inbred and outbred families.
Rearing capacity of circular containers of different sizes for fry and fingerling rainbow trout
No abstract available.
Rearing system for small groups of experimental fish
No abstract available.