ABSTRACT. Many anadromous salmonid stocks in the Pacific Northwest are at their lowest recorded levels, which has raised questions regarding their long-term persistence under current conditions. There are a number of factors, such as freshwater spawning and rearing habitat, that could potentially influence their numbers. Therefore, we used the latest advances in information-theoretic methods in a twostage modeling process to investigate relationships between landscape-level habitat attributes and maximum recruitment of 25 index stocks of chinook salmon (Onocorhynchus tshawytscha) in the Columbia River basin. Our first-stage model selection results indicated that the Ricker-type, stock recruitment model with a constant Ricker a, i.e., recruitsper-spawner at low numbers of fish) across stocks was the only plausible one given these data, which contrasted with

Influence of climate and reproductive timing on

The detection of reductions in effective population size (N,) or census size (N,) is essential for conservation. Recent developments allow wildlife researchers to obtain genetic material via non-invasive sampling techniques that may provide the large sample sizes necessary for precise estimates of N, and N,. Population genetic theory provides several methods to estimate N, from allele frequency data: including temporal change in allele frequencies, gametic disequilibrium and heterozygote excess methods. Modification of capture-mark-recapture methods for use with multi-locus genotype data provides new means for estimating N,. The combination of new DNA sampling techniques, polymerase chain reaction-based DNA markers and analytical methods may provide unprecedented power to detect reductions in N, and N, of endangered populations. However, these genetic methods are largely untested in the field. We review some relatively unexplored, but promising ways that multi-locus genetic data can be used to provide important genetic and demographic information and suggest avenues for further research in this area. t

We test the ability of gene flow to alleviate the deleterious effects of inbreeding in a small mammal, the deer mouse (Peromyscus maniculatus). After three generations of sib–sib mating, individuals from three lines of mice were either subject to further inbreeding or were mated with an outbred individual. Subsequently, these mice, plus a control line, which were first generation (F1) mice from unrelated individuals kept in captivity for the same duration as the treatment lines, were released into isolated pens in a forest in western Montana. Survival of individual mice was recorded. Survival models that allowed variation in breeding treatments were well supported, whereas models explaining variation in line, or release location were not well supported. Survival was highest for offspring of the outcross group, intermediate for the inbred animals, and lowest for the control group. This suggests that the introduction of migrants can reduce inbreeding depression, as theory predicts. We also show limited evidence for purging of deleterious recessive alleles that can cause inbreeding depression. While purging may have occurred, the demographic cost was non-trivial as 5 of 8 of our inbred mouse lines went extinct during the inbreeding process.

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Site fidelity of the declining amphibian Rana

This thesis develops the first open population model for any shark species worldwide using the Cormack-Jolly-Seber (CJS) model. In conjunction with a tagging study, five auxiliary studies were conducted to investigate stock structure, post-release mortality, tag shedding, and tag-reporting rates. The results from each of the studies were used to correct for any violations of the models assumptions to provide the first unbiased estimates of survival and abundance for the raggedtooth shark (Carcharias taurus) in South Africa. The C. taurus population exhibited complex stock structuring, by size and sex. Competitive shore anglers fished an estimated 37, 820 fishing days.year-1 (95 % C.I. = 28, 281- 47, 359 days.year-1) for sharks, and caught 1764 (95 % C.I. = 321 – 3207) C. taurus. Although released alive, post-release mortality ranged from 3.85 % for young-of-the-year sharks to 18.46 % for adult sharks. Between 1984 and 2004, a total of 3471 C. taurus were tagged. In all, 302-tagged sharks (8.7%) were recaptured. Both juvenile (< 1.8 m TL) and adult sharks (> 1.8 m TL) displayed philopatric behaviour for specific parts of their ranges, including gestating and parturition areas. Significant differences were

survival be estimated from the yellowtail tag-recapture database?

Reference to material in this report should be cited thus:

Recently, much knowledge has been gained about variation in mammalian life-history traits such as litter size, gestation length, birth mass, weaning mass, age at first breeding, breeding interval, and life span (see Roff 1992; Stearns 1992 for reviews). Life span (length of life) is one of the most influential lifehistory traits related to individual fitness, from both demographic and evolutionary viewpoints. Differences in life span account for much of the variation in individual fitness in many vertebrate populations (Clutton-Brock 1988; Newton 1989). Among species, the variability in life span is expected to be related to body size (Peters 1983), phylogeny (Harvey and Pagel 1991), and ecological characteristics (Calder 1984). Within species, the main causes of variation in life span should be both tradeoffs between reproduction and survival (Stearns 1992) and individual differences in phenotypic quality (Clutton-Brock 1991). The objective of this chapter is to present a comprehensive picture of levels and trends of variation in mammalian life span at both intra- and interspecific levels. Improved description and analysis might also be useful