The ex-vessel coho salmon market has been paid scant attention in the study of the salmon resources. This study is an attempt to advance an understanding of the variations of ex-vessel prices and landings during the coho season as well as between the various coastal ports where the fish is landed. This study presents an empirical analysis of the ex-vessel port markets for coho salmon in Oregon and Washington. The objectives of the study are to investigate the variation in landings and prices during the fishing season and to compare those differences between ports for both states. This study focuses on the determination of the ex-vessel price mechanism and the decision behavior of coho fishermen in their choice of ports to land the catch. An economic model of each port is developed to explain the buying behavior of processors and the selling behavior of fishermen. Each port is treated as a distinctive market subject to external changes in the abundance of coho, the conditions of the wholesale markets, and the responsiveness of fishermen to prices in other ports. Several econometric models are constructed to determine the distinctive characteristics of the Oregon and Washington ex-vessel port markets. The demand and supply at the different ports are estimated by applying regression analysis to 32 different sets of data. These data include a single year (1976) of transaction records for the twelve Oregon ports, and four years (1973-1976) of landings records for the five Washington coastal ports. Three different models are used; a simultaneous equations model, a recursive model, and a single equation model. The major findings in the study are as follows: the ex-vessel demand in most Oregon or Washington ports is highly elastic, which suggests that changes in seasonal landings at a port do not have any significant impact on the ex-vessel price. While fishermen and other industry observers have noted differences in seasonal ex-vessel price between ports, such differences do not appear to exist. Average seasonal price differences between ports do not vary when appropriate weights are applied to the average price calculations. The size (in pounds) of the coho salmon plays a major role in the determination of the intraseasonal ex-vessel demand at all ports. Estimations performed without accounting for this variation fail to adequately explain ex-vessel price variation. Another variable found to be a key factor in the explanation of ex-vessel prices is the wholesale price. This factor and the size variable accounted for most of the variation in ex-vessel port prices. Even though the seasonal prices between ports are similar, the intraseasonal variation in port price is partly the result of competition for the fisherman's catch of coho. When two ports are located in such a way that fishermen may easily land at either one, fishermen appear to land at the port where price is greater. Ports such as La Push and Neah Bay in Washington, and Bandon and Winchester Bay in Oregon are the ports found to be alternative ports for the fishermen catching coho in those areas. Coastal ex-vessel prices do not appear to be established as a result of equilibrium conditions at any particular port. Rather, ex-vessel price and market clearing quantities are determined in the aggregate. Each port's buyers will establish port price based on the current aggregate equilibrium condition. The aggregate coastal demand for coho at the ex-vessel level was estimated for the 1976 season and found to be highly price elastic. Given that aggregate supplies are augmentable, increases in coastal landings will increase total returns to the ex-vessel fishery. One additional finding suggests that the number of buyers in most ports does not play a significant role in the determination of intraseasonal variation of port ex-vessel prices. / Graduation date: 1979