Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 151-160). Description: xiii, 160 leaves : ill. ; 29 cm.

The Dungeness crab (Cancer magister Dana) trap fishery in British Columbia has been regulated by a minimum legal size limit of 165 mm spine-to-spine carapace width (CW, 154 mm notch-to-notch CW) since early this century. Evaluation of the size limit by yield- and eggs-per-recruit analyses has been precluded by a lack of information on basic population variables such as growth, mortality, movement and mating behavior. Information on these variables was obtained in an intensive two year study of the Dungeness crab fishery near Tofino, B.C. from April 1985 until March 1987. A cohort of pre-recruit males and females was followed as the males entered the fishery and were subsequently exploited, yielding information on moult increments-at-size , length of intermoult periods, size-at-maturity, size of mating pairs, mortality, movement, commercial fishing success and exploitation rates. Male C .magister entered the fishery during their fourth year after settlement. Size frequency analysis revealed that nearly all legal-sized (>154 mm notch-to-notch CW) males are within the 155.0±11.2 mm instar (≈50% of this instar). Sublegal-sized males in this instar have a high annual natural mortality rate (M=2.8-4.5), hence a low probability (<10%) of surviving to legal size. Legal-sized males have a high annual fishing mortality rate (F=5.1-6.9). Consequently, a small component of the commercial catch is composed of males in larger instars. Despite females not being landed, the negative slope of female catch curves from four regional fisheries was steepest for the most heavily fished region and shallowest for the most lightly fished region. Females mate after moulting while accompanied by a larger male, and in a heavily fished population larger males may be absent. Thus, the catch curves suggested the possibility of reduced mating and moulting, and consequently fewer large females, in heavily fished populations. Yield-per-recruit analysis suggests landings might be markedly improved by lowering the minimum legal size limit. However, eggs-per-recruit analysis, which modeled the possible consequences of removing large males, suggests that for a heavily fished population the current size limit may result in up to a 50% decline in population egg production relative to an unfished population. The historical presumption that the current minimum legal size limit for males does not impact on population egg production should be reconsidered. To facilitate calibration of trap samples biased by differences in soak times, parameters for models describing changes in bait effectiveness over time, and agonistic interactions between crabs within a trap and those attempting to enter that trap, were estimated. Parameter estimates were obtained by simulating the entry and exit of crabs into and out of traps based on experiments which (1) emphasized the above two processes, and (2) estimated the daily probabilities of crabs of different sizes escaping traps. / Science, Faculty of / Zoology, Department of / Graduate

The microsporidian parasite Nadelspora canceri infects Dungeness crabs, Cancer magister, along the United States Pacific Northwest coast. The prevalence and seasonal variation of N. canceri in Dungeness crabs from Alsea Bay, Oregon, are described based on examination of 2991 crabs collected at monthly intervals from October, 1991 to June, 1993. The average prevalence in monthly samples was 21.0% and ranged from 8.2% to 33.0%. No significant differences in monthly or seasonal parasite prevalence were observed. A total of 3061 Dungeness crabs was examined from an additional seven Pacific Northwest estuaries and Puget Sound to document the geographic distribution of N. canceri and the prevalence of the parasite in these locations. The estuaries sampled and the prevalences observed were: Humboldt Bay, California (14.6%), Coos Bay (10.6%), Yaquina Bay (2.0%), Tillamook Bay (41.2%), and Nehalem Bay, Oregon (14.2%), Willapa Bay (6.9%), and Grays Harbor Washington (0.44%). Dungeness crabs were examined from the Dungeness spit, Kala Point, and Mukilteo areas in Puget Sound and no infected crabs were found. A total of 9317 male Dungeness crabs > 15.9 cm carapace width (CW) captured in the commercial ocean crab fishery was examined for N. canceri and 27 (0.3%) were infected with the parasite. No infections were found in crabs smaller than 3.0 cm CW and the prevalence of infection generally increased with crab size reaching a peak of 22.2% in 14 cm CW crabs. The overall infection prevalence in male crabs (19.2%) was more than twice that of female crabs (8.0%), and of the 821 infected crabs found, 629 (76.6%) were males. The mortality of laboratory-held Dungeness crabs naturally infected with N. canceri was compared to that of uninfected crabs in two separate experiments and in both cases a significantly higher mortality was observed for infected crabs. Nadelspora canceri infections were established in both juvenile and adult Dungeness crabs that were fed parasite spores in laboratory experiments indicating that transmission is direct and intermediate hosts or vectors are not required for transmitting the parasite between hosts. / Graduation date: 1995

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 179-196). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph.D.) - Simon Fraser University, 2004. / Theses (Dept. of Biological Sciences) / Simon Fraser University.

viii, 61 leaves : ill. ; 28 cm Typescript. (Another copy on microfilm is located in Archives) Thesis (M.S.)--University of Oregon Includes vita and abstract Bibliography: leaves 57-61 University of Oregon theses, Dept. of Biology, M.S., 1980

The International Commission on Radiological Protection (ICRP) has modeled twelve reference animal and plant (RAP) species using simple geometric shapes in Monte���Carlo (MCNP) based simulations. The focus has now shifted to creating voxel phantoms of each RAP to advance the understanding of radiation interactions in nonhuman biota. The work contained herein presents results for the voxel phantom of the Dungeness crab, Metacarcinus magister, the Sand Dab, Limanda limanda, and the brown seaweed, Fucus vesiculosus, and details a generalized framework for creating voxel phantoms of the other RAPs. Absorbed fractions (AFs) for all identified organs were calculated at several discrete initial energies: 0.01, 0.015, 0.02, 0.03, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, and 4.0 MeV for photons and 0.1, 0.2, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0 and 4.0 MeV for electrons. AFs were then tabulated for each organ as a source and target at each energy listed above. AFs whose error exceeded 5% are marked with an underline in the data tables; AFs whose error was higher than 10% are shown in the tabulated data as a dashed line. The AF���s were highly dependent on organ mass and geometry. For photons above 0.5 MeV and electrons above 0.2-0.4 MeV a nontrivial amount of energy escapes the source organ. / Graduation date: 2013

No description available.