The effect of brine- and plate-freezing and length of subsequent frozen storage upon flesh pH, thaw drip, color, flavor, TBA (2-thiobarbituric acid) values, and long chain free fatty acids of Pacific halibut, Chinook and Coho salmon was determined. The effect of freezing method upon sodium, potassium, and chloride concentration was also determined. Flesh pH of all three species generally declined significantly (P ≤ 0.05) with length of storage. The thaw drip of Pacific halibut and Chinook salmon was less for the brine- than the plate-frozen samples after storage for 9 to 31 weeks whereas subsequently the brine-frozen samples had approximately equal or greater thaw drip than the plate-frozen. The thaw drip of all samples, except those from plate-frozen halibut, tended to increase with length of storage. The Hunter 'a' and a/b values of Chinook and Coho salmon generally increased during storage. The difference in flavor between brine- and plate-frozen outside muscle of halibut and Chinook salmon reached a maximum at 31 and 26 weeks of storage respectively, and then steadily decreased. In contrast, the difference in flavor between brine- and plate-frozen Coho salmon outside muscle steadily increased during storage. The difference in flavor between brine- and plate-frozen inside muscle of all species, except for the Coho salmon at 10 weeks and halibut at 31, 62 and 81 weeks of storage, was not significant. The difference in TBA values (an index of oxidative rancidity) between brine- and plate-frozen outside muscle samples rapidly increased and reached a maximum at 45, 26, or 27 weeks (the brine-frozen samples having the higher values) then decreased until there was approximately no difference at 81, 77 and 78 weeks of storage for halibut, Chinook and Coho salmon, respectively. Method of freezing or length of storage had little effect on the TBA values of inside muscle for all species. Method of freezing had little effect on the concentration of individual free fatty acids (percentage of total free fatty acids analyzed). The concentrations of several free fatty acids was affected by length of storage but the pattern of change during storage was erratic. Freezing method had an effect on the concentration of some individual free fatty acids (μ.g per gram of neutral lipid) of halibut and Chinook salmon but not of Coho salmon. In general, with all species, the concentration of the individual free fatty acids was greatest in the inside muscle. Also for halibut and Chinook salmon, particularly where there was a significant difference among storage times, the concentration of the free fatty acids rapidly increased during the first 26 to 31 weeks of storage. Method of freezing and length of frozen storage had a significant effect on total free fatty acids analyzed for only Chinook salmon. Total free fatty acids significantly (P ≤ 0.05) differed between inside and outside muscle of halibut and Chinook salmon but not of Coho salmon. The effect of method of freezing upon potassium concentration was small and varied with species. The effect of brine-freezing upon most variables measured was either small and/or complex. For all three species the sodium and chloride concentration was two to three times greater in the brine-frozen outside muscle than in all other samples. The taste panel results and the TBA values indicate that brine-freezing does impair the quality of the outside muscle of halibut and Chinook salmon during the early stages of frozen storage. / Land and Food Systems, Faculty 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

Burrowing is most energy costly behavior. Many vertebrates burrow head-first into the sediment. Interestingly, head-first burial fishes differ in head shapes by having either a flatten or conical head shape. Head shape determines the penetration force magnitudes, but it is important for their neurocranium to avoid overwhelming cranial stresses from those burial forces. There is minimal research on the penetration force (N), rotational resistance (Nmm), and cranial stress (Pa) for different head shapes. Here, we selected four members with different head shapes: Tetraodon miurus (Bulky), Iniistius pavo (knife edge), Bunocephalus coracoideus (shovel), and Cheilio inermis (knife point). We constructed 3D head shape models and controlled the surface areas. We recorded penetration force (N) and torque (Nmm) for each model. We also constructed the neurocranium models and loaded them in Finite Element Analysis (FEA) to examine the stress magnitudes and concentrations. Our results show that bulky penetrated with highest penetration force, and knife point and shovel penetrated the minimum force. Knife edge experienced the greatest sediment resistance. Knife point succumbed to highest stress magnitude. The premaxillae and maxillae were the bones constraining burial for shovel. The parasphenoid bone constrained knife edge, knife point, and bulky during burial. From our results, having larger wide head dimensions and larger volumes generated greater penetration forces. Those with a flatten head succumbed to high sediment rotational resistance. Bone arrangements influences stress magnitudes because those with different skull shapes, yet same bone arrangements were constrained by the same bone. It seems there is a tradeoff between penetration force and cranial stress magnitudes. Fish use their parasphenoid for feeding and burial for those in our study, so there may be relationship between burial and feeding.

Thesis (Ph. D. (Physiology)) -- University of Limpopo, 1993 / Refer to document

Thesis (M.S.) in Marine Biology--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 44-48).

Thesis (M. Sc.)--University of Hong Kong, 1963. / Type-written copy. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 132-145).

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 37-43).

The object of this study was to investigate character displacement (Brown and Wilson, 1956) and reduction of phenotypic variability with reduction in niche width (Van Valen, 1965). Dolly Varden from one sympatric (Loon Lake) and two allopatric (Dickson and Foley Lake) populations were compared. Field studies showed that the niche width of sympatric Dolly Varden was less than that of allopatric Dolly Varden owing to food and spatial segregation, confirming results of an earlier study (Andrusak and Northcote, 1971). Character displacement was evident in pyloric caeca numbers and in certain behavioural responses (spatial distribution and feeding) observed in the laboratory. These were accompanied by reduced variability, also apparent in length distributions within year classes, in the sympatric population compared with an allopatric population (Dickson Lake). However, character displacement and reduced variability could not be demonstrated for most morphometric characters, presumably because of the complexity of growth processes involved. Effects of overlapping adjacent year classes and of continuous growth of fish body parts (in contrast to comparable studies with birds) obscured interpretation of such characteristics. / Science, Faculty of / Zoology, Department of / Graduate

Surrounding land-use and in-lake data were collected to determine environmental variables influential in structuring centrarchid assemblages in oxbow lakes of the Mississippi Alluvial Valley (MAV) and to suggest environmental manipulation strategies that may improve the fisheries of these systems. I sampled 53 oxbow lakes using boat electrofishing and land-use data were summarized using ArcView GIS. Non-metric Multidimensional Scaling separated centrarchids according to water quality tolerance. Centrarchid composition was related to land-use, water clarity, maximum depth, connectivity, primary productivity, and physicochemistry as determined by Canonical Analysis of Principal Coordinates. Canonical Correspondence Analysis rejected the null hypothesis of no relationship between land-use and centrarchid proportional composition. Environmental variables were related significantly to centrarchid composition. Based on these data, a general fisheries management plan for oxbow lakes of the MAV was proposed.