The characteristics of Northern squawfish (Ptychocheilus oregonensis) and the feasibility of utilization of this species for human consumption were investigated. In the first experimental phase, the iced storage characteristics of squawfish were determined. Quality changes were monitored over 24 days of storage by chemical, physical, microbiological and sensorial methods of analysis. The Torrymeter readings, K value, descriptive sensory evaluation and taste panel tests demonstrated that squawfish kept well in ice for 15 days. The torsion test results showed that squawfish exhibited good gel forming ability and decreased only 15% of the original value after 24 days of iced storage. The K value might provide the basis of a raw material quality control system for processing. Production of deboned fish mince could be an effective method for utilization of bony squawfish. In the second experimental phase, quality of minced flesh from squawfish was investigated. Texture properties of minced gels as determined by torsional shear stress and strain, at fracture, showed that there was no significant difference in strain value between unwashed and washed mince. No significant differences were also found in strain values of minced gels due to different temperature settings. The addition of cryoprotectants was very effective in maintaining strain value for both unwashed and washed mince during three months of frozen storage. Thiobarbituric acid (TBA) analyses showed minced flesh maintained good quality with regard to oxidation. In the third experimental phase, the suitability of squawfish (Ptychocheilus oregonensis) as a potential species for surimi processing was investigated on the basis of post harvest freshness. The yield of surimi from whole fish ranged between 15.5-21.6%. Fish freshness had a positive correlation with initial surimi quality. The quality changes of surimi during frozen storage depended upon the freshness of material and were influenced by the duration of storage. One wash cycle improved the color of surimi gel significantly. However, there were no significant differences in strain values measured by torsion test due to different wash cycles. Results of the experiment indicated that it was feasible to produce surimi from squawfish stored on ice for up to 9 days. One wash-cycle was adequate for squawfish surimi production. / Graduation date: 1994

Thesis (M.S.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 65-70). Also available via Humboldt Digital Scholar.

This study examined the diet composition of ninety-nine Sacramento pikeminnow (150-410 mm [5.9-16 in] fork length [FL]) collected from the upper and lower main stem of Chorro Creek, Morro Bay Watershed, California in 2006. The goal of this study was to characterize the spatial and seasonal variability in the diet of Sacramento pikeminnow within Chorro Creek and to determine what proportion of the diet is represented by rainbow trout (Oncorhynchus mykiss) and their anadromous form (steelhead). Prey was identified in 88% of the samples collected in the early season and 84% of the samples collected in the late season. Fish and/or scales were identified in 12% of the samples collected. Sacramento pikeminnow consumed a wide variety of prey; the diversity of individual diets was higher in the lower main stem than the upper. Overall, diet diversity increased with Sacramento pikeminnow length. In both the early and late season, crayfish formed the largest part of the diet of large Sacramento pikeminnow (>250 mm [9.8 in]). There was a slight increase in the proportion of fish in the diet during the late season, and tendency for cannibalism which was primarily observed in the upper main stem of Chorro Creek. In summary, the overall results of this study support the conclusion that Sacramento pikeminnow are not significant predators of O. mykiss in natural stream conditions. However, conclusions about the ability of Sacramento pikeminnow in Chorro Creek to reduce O. mykiss populations will require further information on the prey selection of Sacramento pikeminnow when juvenile O. mykiss and adult pikeminnow are abundant.