Christophe M. Herbinger

DNA fingerprint based analysis of paternal and maternal effects on offspring growth and survival in communally reared rainbow trout

Abstract This study was initiated to assess the feasibility of establishing pedigrees in mixed aquaculture populations and of selection programs for commercial aquaculture operations based on genetic profiling data from microsatellite markers. Complete factorial crosses between ten sires and ten dams were performed in a small rainbow trout farm. The largest and smallest progenies were sampled after 1 year of communal rearing, and their parentage was established with four or five microsatellite markers. About 91% of the fish could be traced to one or two parental couples out of the 100 possible couples. There were significant differences among sires and dams for the growth and survival of their progeny. There were also indications that progeny of inbred crosses have depressed performances. Based on these results, a breed improvement program has been implemented in this small hatchery.

Early growth performance of Atlantic salmon full-sib families reared in single family tanks versus in mixed family tanks

The present experiment was designed to assess the impact of the confounding of environmental tank effect with genetic family effect during early rearing periods. In November 1989, two sets of mixed family tanks were created in the Salmon Genetic Research Program (SGRP) hatchery by pooling equal numbers of eggs from four and eight families, respectively. In July 1990, tissue samples and length and weight measurements were collected on fish from both individual family tanks and mixed family tanks. Four polymorphic microsatellites were used to determine unambiguously the family of origin of 790 mixed group fish. There was a strong correlation of family survival rates measured in the mixed tanks and in the single family tanks. Differences among families for length and growth were observed in both the mixed tanks and the single family tanks. However, family growth performance in the single tank environment was poorly correlated with family growth performance in the mixed tank environment and appeared to reflect environmental differences among tanks rather than genetic differences among families. Neither family growth performance in the mixed tanks nor in the single family tanks appeared strongly correlated with subsequent family growth performance up to smolt stage.

Genetic structure and relationships among steelhead trout (Oncorhynchus mykiss) populations in British Columbia

Steelhead trout, Oncorhynchus mykiss (the anadromous form of rainbow trout), are declining over much of their range around the Pacific rim. We nondestructively collected tissue samples from 494 adult steelhead from eight tributaries and two mainstem river sites within three watersheds in northern British Columbia, Canada. We scored allele size for six highly polymorphic microsatellite DNA loci and provide primer sequences and polymerase chain reaction conditions for five of these loci for the first time. The populations were significantly genetically differentiated (θ = 0.039; 95% confidence = 0.030–0.053). AMOVA showed that most of the genetic variation was at the individual level (95.6%), although significant genetic variation existed at the tributary level (3.09%) and watershed level (1.31%). The calculated unbiased genetic distances were positively correlated with geographical distance within watersheds (P < 0.01; r2=0.35) indicating probable genetic equilibrium. Tributary populations in two of the watersheds were not as genetically divergent as would be expected given their large geographical separation. Cross-headwater transfers of fish within relatively recent history are the most likely explanation of this anomaly. Seven of the eight tributary populations fit a regression line of mean heterozygosity vs. rearing habitat area. The one anomalous population had a much lower heterozygosity than expected based on the linear regression, and may thus be the population of greatest conservation concern.

Impact of reconstructed pedigrees on progeny-test breeding values in red spruce

Pedigrees reconstructed through DNA marker assigned paternities in polymix (PMX) and open pollinated (OP) progeny tests were analyzed using mixed models to test the effect of unequal male reproductive success and pedigree errors on quantitative genetic parameters. The reconstructed pedigree increased heritabilities in the larger PMX test. Increased heritability resulted from adding the paternities to the pedigree per se, not by correcting the male reproductive bias by specifying the exact pedigree. Removing hypothesized pedigree errors had no effect on quantitative parameters, either because the magnitude of the errors was too small (PMX) or the progeny test was too small to detect variance components reliably (OP). Although there was no advantage in backwards selection, the increased additive variance, heritabilities and accuracy of progeny with assigned paternities in the pedigree, should permit forward selection of offspring with greater genetic gain and complete control of coancestry for future breeding decisions. Some possible breeding population structures with the new genetic information are discussed.

Sources of family variability for maturation incidence in cultivated Atlantic salmon

Abstract Two cohorts of Atlantic salmon ( Salmo salar ) belonging to several different families were followed from hatching to grilse maturation. Large and concordant differences among families for grilse, post-smolt precocious and precocious maturation rates were observed. These differences appeared to be mainly due to differences among families for the relative allocation of energy into somatic growth versus body reserves maintenance, and to a lesser extent, to differences among families for winter growth capabilities.

GENETIC DIVERSITY OF THE EUROPEAN OYSTER (OSTREA EDULIS L.) IN NOVA SCOTIA: COMPARISON WITH OTHER PARTS OF CANADA, MAINE AND EUROPE AND IMPLICATIONS FOR BROODSTOCK MANAGEMENT

Abstract The European oyster (Ostrea edulis) was introduced to the Nova Scotia aquaculture industry 30 years ago using stocks imported from naturalized populations in Maine whose ancestors originated in the Netherlands. This study used 5 microsatellites to assess the level of genetic diversity in several hatchery stocks and naturalized populations from Nova Scotia, New Brunswick, British Columbia and Maine. Some genetic erosion was shown to have occurred in the Maritimes populations, with the largest loss of alleles being experienced by the hatchery stocks. In spite of this loss, genetic diversity and heterozygosity in the Maritimes populations are still relatively high. Relationships within and between the populations and the existence of kin groups within the collections were overall consistent with our knowledge of the historical transfers of oysters between different locations. Furthermore, the established database allowed to assign with good confidence unknown oyster samples to their geographic origin. This would be a useful forensics tool in the case of an illegal transfer from a diseased area.