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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

The purpose of this research was to explore the impact of finfish bycatch on the ocean shrimp Pandalus jordani fishery using two methods. One method looked at the breakage of the shrimp by finfish bycatch in the nets. The other looked at the impact of bycatch on fishing decisions. At-sea research found that finfish bycatch contributes to the breakage of ocean shrimp. However, the impact is small relative to breakage caused by other handling procedures. Bycatch was measured from each net of a double-rigged shrimp vessel, where one side employed a Nordmore grate bycatch reduction device (BRD) and the other served as a control. Shrimp catch was controlled for BRD use and catch day, and sampled throughout processing to evaluate breakage. At greater than 50% bycatch there was a significantly higher percentage of broken shrimp in the control side than in the BRD side for samples taken at the first and third sampling point (p<0.05). After this point the differences became non-significant. The percent breakage increased from a mean 2.4% broken before placement in the hold to a mean 18.0% broken in the final product. The impact of bycatch on fishing decisions was evaluated by distributing an expanded logbook to volunteer Oregon shrimp vessels in 1998. Logbook questions addressed the reasons and time involved for running to initial fishing grounds, relocating overnight, relocating between tows, dumping tows, and modifying gear. Completed logbooks were collected from 20 vessels representing 263 trips, 1043 fishing days, and 4727 tows. A soft mesh BRD was used at some point by 25% of vessels on 8.7% of trips and 3.3% of tows. Bycatch did not figure prominently in reasons given for choice of initial fishing grounds, relocating between fishing days, or relocating between tows. Bycatch was the main reason cited for dumping tows. In total, 430 (9%) tows were dumped. The estimated weight of fish and shrimp dumped equaled 11.3% and 0.3%, respectively, of the landed shrimp catch. Pacific whiting Merluccius productus caused 81.4% of the tows dumped due to bycatch. Opportunity costs attributed to bycatch alone were equivalent to net revenue resulting from 12.3 tows or $3,203 per study vessel. At the fleet level, opportunity costs due to dumped tows totaled 1,227 effort hours, 32.4 trips, or $155,070. This equates to a 4.6% loss in gross ex-vessel revenue. / Graduation date: 2002

Thesis (M.S.)--Corpus Christi State University, 1980. / "Conducted in cooperation with the U.S. Department of Commerce, NOAA, National Marine Fisheries Service under P.L. 88-309 (Project no. 2-202-R)." Includes bibliographical references (p. 24-26).

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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Thesis (M.S.)--Mississippi State University. Department of Food Science, Nutrition and Health Promotion. / Title from title screen. Includes bibliographical references.

Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1979. / Bibliography: leaves 112-115. / Microfiche. / x, 115 leaves ill. 29 cm

Thesis (M.Sc. (Zoology & Entomology)) - Rhodes University, 2007.