Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. / Includes bibliographical references. Also available on microfiche.

For a variety of stock-recruit systems in which environmental variability is simulated by random normal deviates used as multipliers or divisors Ricker (1958) and Larkin and Ricker (1964) demonstrated the benefits of complete stabilization of escapement as opposed to removal of a fixed proportion of the stock each year. Part I is primarily concerned with the response of these same systems to a pattern of stochastic modification which is more regular in form, a pattern such as might be imagined to result from long-term trends in environmental conditions. In addition, some mathematical properties of these systems are discussed. Part II considers the stock-recruit relationship from a more reductionist or mechanistic point of view. Evidence for differential utilization of spawning areas is presented and spawner distributions in three different environments are compared. These results are discussed in terms of their relevance to existing stock-recruit theory. Also, observations on egg retention and social facilitation are presented. / Science, Faculty of / Zoology, Department of / Graduate

A field evaluation of the dichotomous technique was made using 1965 data from the Rivers Inlet sockeye salmon population. An estimate of preexploitation population size was made with the compositions of the pre- and post-exploitation populations and the catch. The estimate was made through the application of simultaneous equations and a maximum likelihood estimator formulation to changes in population composition resulting from selective removal. Biased data was shown to greatly affect the estimates of population size. A wide range of population estimates was derived from the various dichotomous characters utilized. Graphical analysis of these estimates provided an overall estimate of the population. The physical restrictions of the research area made this estimate of considerable value. Relative to most other population estimation techniques, the dichotomous method has wider potential use because of its less restrictive basic assumptions. This flexibility can be accompanied, however, by a reduction in the accuracy of resultant estimates. / Science, Faculty of / Zoology, Department of / Graduate

Ricker (1954) derived a stock recruitment relationship from assumptions involving cannibalism or other compensatory density dependent mechanisms. His relationship indicates a decline in reproduction at high stock densities of spawners, the result of which may give a population a tendency to oscillate in numbers. The object of this study was to examine, using Ricker’s stock-recruitment model, the period and amplitude of cyclical fluctuations in numbers of animals as they are related to intrinsic factors such as age of first maturity, number of generations in the spawning stock and the shape of the reproduction curve, and extrinsic factors such as exploitation and random fluctuating environment. In lightly exploited populations the period of oscillation is dependent on age of first maturity and number of generations in the spawning stock, the period being equal to twice the mean age of maturity. In heavily exploited populations, the period of oscillation is dependent on age of first maturity but independent of the number of generations in the spawning stock, the period being equal to approximately twice the age of first maturity. When random fluctuations are added to the system, cyclic changes are maintained at low effects of random factors but they introduce instability in the oscillation and variability in the period of oscillation as they become more effective. The shape of a reproduction curve does not influence the period of population oscillation but the steeper the right hand limb of the curve the greater is the amplitude of the fluctuation. The amplitude of oscillation in numbers is basically determined by the shape of a reproduction curve and it increases with delayed maturity while it decreases with increasing number of ages spawning and increasing exploitation. It was considered doubtful whether the observed high reduction in the period of oscillation would every be big enough to notice, in natural populations, before exploitation removed oscillations completely and stabilised population abundances. / Science, Faculty of / Zoology, Department of / Graduate

Methods of search in marine fisheries are reviewed, and aspects of variables necessary to evaluate exploitation strategies are considered. Estimates of fish school densities based on gas diffusion principles are made. Possible school patterns are examined using the Poisson, Poisson with added zeroes, Neyman type A and Negative Binomial distributions. The Negative Binomial distribution was found to give best fit to the data used although the Neyman type A distribution gave a better estimate of the data variance. School size was reasonably well described by a log distribution, Mean square dispersion rates, modal velocities and direction of movement for sets of observations on tuna schools are found. Tests on the significance of direction of movement by groups of tuna school are done and those groups showing significance were tested for homogeneity of direction. Confidence intervals on the movement of direction are also calculated. Decision methods so as to increase catch are considered for three situations: (1) Where the position of a school is known with some error, and it must be decided whether to attempt to locate it or remain searching on the present grounds. (2) When the Bayes estimate of catch rate on the present grounds is less than that expected on an alternate ground, and the decision of changing depends on minimizing an expected loss function. (3) For the Vancouver trawl fishery where fish occurrence may be considered of a present or absent nature, and it is desired to minimize the time spent steaming between grounds. The use of entropy as a criterion of search effectiveness as used by other workers is also discussed. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Oregon State University, 1966. / Typescript (Photocopy). Includes bibliographical references (p. 218-221). Also available via the World Wide Web.

The purpose of this research was to determine population trends of major nearshore fish species in Indiana waters of Lake Michigan from 1984 to 1998 to gain insight into species dynamics. Index trawl samples were collected twice monthly from June through August at three locations. Trends of catch-per-unit-effort (CPUE) were investigated for the most abundant species: yellow perch (Perca flavescens), alewife (Alosa pseudoharengus), spottail shiner (Notropis hudsonius), rainbow smelt (Osmerus mord iz), and bloater (Coregonus hoyi). Trawl catch of yellow perch, alewife, and spottail shiners at sites M, K, and G were strongly correlated suggesting similar fluctuations. Young-of-the-year trawl catch revealed that insight to population dynamics of species was not always reliable. Trawl CPUE of > age 1 fish provided insight to dynamics of the major species at all sample locations with strong trend similarities between sites. No strong major species interactions were found using simple linear correlations. / Department of Biology

Thesis (M.S.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliographical references (leaves 106-110). Also available on the World Wide Web.

Thèse (M.Sc)--Université Laval, 2003. / "Offerte à l'Université du Québec à Chicoutimi en vertu d'un protocole d'entente avec l'Université Laval"--P. de t. Bibliogr.: f. [79]-83. Publié aussi en version électronique.

Thèse (de maîtrise)--Université Laval, 2002. / "Mémoire présenté à l'Université Laval comme exigence partielle de la maîtrise en médecine expérimentale offerte à L'Université du Québec à Chicoutimi en vertu d'un protocole d'entente avec l'Université Laval". Bibliogr.: f. [81]-83. Publié aussi en version électronique.