Growing demand for limited quantities of fish has led to systematic planning for the conservation and management of U.S. fishery resources. There is a need for better understanding of the complex biological and social environment on which regulation for conservation, social, and economic purposes is imposed. The behavior of commercial fishermen, who in many instances use multi-purpose vessels to exploit multi-species fisheries, is difficult to assess and predict. The purpose of this thesis is to describe and analyze selected aspects of Oregon commercial fishing fleets. The focus of this study is on the short-run decision-making behavior of Oregon trawl fishermen for the period 1974-1979. A general review of the activities of Oregon's multi-purpose fishing fleets is followed by an attempt to measure the responses of trawl vessel operators to varying economic and biological conditions. Several models of the short-run allocation of fishing time by a multi-purpose vessel operator are developed. The limited amount of economic literature on multi-purpose fleet behavior is briefly reviewed. An important feature not explicitly recognized in the theoretical models is that fishermen operate in an uncertain environment. Fishermen are hypothesized to react to expectations about economic returns in the fisheries which they can exploit. Simple Nerlovian agricultural supply response models were adapted for statistical analysis of the allocation of fishing time. Fishermen's short-run behavior was hypothesized to depend on expectations of current rather than normal returns to fishing time. Four versions of models which explain allocation of fishing time for a stable subfleet of trawl vessels were estimated using ordinary least squares regression. Monthly days of fishing by fishery were significantly explained by variables representing expected gross revenues per unit of effort, weather conditions and seasonal regulations. The analysis also indicates that fishermen are able to respond rapidly to perceived variations in gross returns. In the shrimp and crab fisheries, elasticities of days fished with respect to expected gross returns were estimated to be in the range of 0.45 to 0.40. Regulatory implications are that: (1) fisheries managers need to monitor the effects of regulation with little delay and (2) the use of taxes and subsidies to shift significant amounts of effort among fisheries is not likely to be successful. Additional research effort could profitably be spent to refine measurement of the explanatory variables, or to measure the response of individual fishermen to suitable explanatory variables. / Graduation date: 1982

Fishing firms in Oregon operate in a complex and dynamic physical, biological and institutional environment. Within this environment, managers of these firms will attempt to maximize some objective function which may include profit. This maximization is dependent upon the level of output, or the levels of inputs. Given a relationship between output and inputs, production economics theory tells us how to combine inputs so that an optimum level of output is achieved. This study applies production economics theory to commercial fishing firms in Oregon. The primary objective of this research was to determine whether a relationship between output and production inputs could be estimated statistically and provide the marginal value product information to determine the optimum combination of inputs. A second objective was to determine whether a statistical relationship could be estimated which would predict fuel use in terms of physical boat characteristics for the fishing firms in Oregon. Cross-section data were obtained for analysis from a mail survey of the population of 4,462 commercial fishing firms. Response to the survey was excellent, with 45 percent of the surveys returned. The data were used to estimate production relationships among the fishing firms using gross revenue as a dependent variable and independent variables measuring boat length, engine horsepower, hold capacity, fuel consumed fishing in 1979, mandays of labor used, years fishing experience of the skipper, capital investment in electronic gear and capital investment in deck gear. Two functional forms for regression were used; log-linear and linear. It was expected that the log-linear form of the model would provide the best estimate based on its convenient mathematical characteristics and wide use in empirical research applications. It turned out, however, that the better estimate was obtained with the linear form of the model. This estimate was interpreted as a linear approximation to a segment of the production function and was used to calculate estimates of the marginal value products for the production inputs. To investigate whether a better estimate of the production relationship could be obtained by disaggregating the sample, two disaggregations were tried. The sample was disaggregated into groups of firms having similar characteristics of species fished and also boat length groupings. The results obtained from these estimations were statistically inferior to the estimated relationship using the full sample. The conclusion was made that the production relationships were better estimated across all firms in the sample rather than by disaggregation. The estimation of fuel use by boat characteristics was reasonably successful. Again, a linear model was chosen as the best statistical relationship. The model estimated fuel use by boat length, engine horsepower and mandays of labor. A prediction of the fuel used by all fishing firms was made using data on the population of fishing firms from the 1979 Oregon Department of Fish and Wildlife license file. The predictive equation used only two variables, boat length and horsepower as these are the only characteristics presently available for the population of firms. / Graduation date: 1981

Graduation date: 1975

The ocean fishery is an example of a common property resource industry. Behavior of commercial fishermen is determined by a complex set of economic, environmental and social factors. All of these factors contribute to the individual fisherman's success. Fishermen learn to cope with the variability inherent to their occupation. Two strategies are observed in fishing behavior: The specialist who operates exclusively in one fishery and the generalist who readily switches fisheries according to market, social or management considerations. Traditional fishery models formulated to predict the behavior of fishermen have focused on the specialist. Smith and McKelvey (1986) and McKelvey (1983, 1987) have provided analyses to suggest these two fishing strategies may co-exist in a fluctuating environment. The purpose of this study is to analyze the Oregon trawl fisheries for the presence of diversification in strategy selection. To gather the data necessary for testing the hypotheses, interviews were conducted in the trawl fisheries of Oregon, June through December 1985. Three groups of fishermen are identified according to strategy selection. Nominal effort differences and capital-to-income ratios are examined for each strategy type. Additional analysis is done to look at the components of income determination through regression analysis. Discriminant analysis is used to examine the fishermen's attitudes toward switching, risk and management concerns. Among the findings of this research is that specialists and generalists do exist but they cannot adequately characterized by exclusively economic measures. Attitudes shown on the part of the fishermen indicate they feel that management is a significant factor contributing to income variability and strategy selection. / Graduation date: 1988

Questions relating to economic performance, biological conservation and variation in resource abundance and harvest of ocean shrimp have led to increasing pressure for management action. Developing effective management policies for this highly variable resource requires a comprehensive understanding of the fishery and marine processes. Important factors in understanding the fishery include oceanographic influences on shrimp distribution, abundance, and fishery and market dynamics. Fishery regulations for Oregon ocean shrimp, Pandalus jordani, are designed to protect age one shrimp from overharvest and sustain long-term fishery benefits. The research presented in this dissertation describes the development and analysis of analytical models ranging from classical, biological based yield-per-recruit management approaches to optimization models that incorporate economic variables and environmental recruitment relationships. This research is composed of three separate but complimentary papers regarding management of the ocean shrimp fishery. In the first paper, a yield-per-recruit analysis found that high natural mortality rates lead to yield maximization by selecting relatively young shrimp. The revenue-per-recruit analysis found that by delaying the season opening date, shrimp revenue would generate higher total revenues, while decreasing total fishing mortality and harvest. The second paper utilized a nonlinear optimization model with cost and market information to compare harvest strategies on fishery yield, gross revenue and discounted net present value (NPV). A key extension modeled a vertically integrated fishery from harvest through processing and compared harvest strategies based on wholesale prices, shrimp quality and processing yields. The optimization model that generated high yields exhibited high levels of effort and landings but low profits and NPV. The revenue policy maximization resulted in allocation of seasonal effort that produced high value older shrimp. NPV maximization generated high value shrimp landings with lower seasonal effort. Variability in shrimp recruitment and the impact on fishery utilization, income and efficiency was analyzed in the third paper. The optimization model that incorporated a stock recruit relationship and effects of environmental variables indicated an optimal harvest strategy that protects the spawning stock within a season and closes the fishery in years of poor recruitment. The results of this research highlight the complexity of management decisions when environmental forces and economic factors are jointly considered. / Graduation date: 2005