Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 74-85.

No description available.

The extraction of nitrogenous compounds from cod (Cadus morhua) offal by enzymic hydrolysis with papain, the membrane separation of the peptides in the soluble fraction and their freeze and membrane concentration were investigated with the aim of obtaining a high yield of functional products. The following aspects were covered: kinetics of the hydrolysis and of the enzyme inactivation, separation of insoluble solids and yield of nitrogen under different operating conditions (water to fish offal ratio, temperature and particle size of the raw material). Three of the processing options -the hydrolyses, without and with added water, and the water extraction of the minced fish offal followed by hydrolysis of the residue- gave nitrogen yields of 51%, 62% and 69% of the total nitrogen in the fish offal, and required water: fish offal ratios of 0,1 and 1.86 respectively. The peptides in the hydrolysate supernatants were not amenable to membrane separation but those in the water extract supernatant could be split by pH precipitation and ultrafiltration. Eight functional properties of the potential products were evaluated. The hydrolysate supernatants lacked most of them except for high solubility but their low ash content and the particular molecular weight distribution of their peptides may be useful in special feeding diets. The pH precipitate and the concentrate from the ultrafiltration of the supernatant from the pH precipitation exhibited all the functional properties tested to some extent. The precipitate exhibited low solubility and high buffering capacity, high viscosity and good foaming properties. The concentrate had good solubility, gel strength and emulsifying properties.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 88-95.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Georges Bank; Atlantic cod; environmental quality. Includes bibliographical references (p. 38-42).

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 125-135.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references.

Thesis (Ph. D.), Memorial University of Newfoundland, 1999. / Bibliography: p. 163-177.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Restricted until November 2001. Includes bibliographical references.

Pacific cod (Gadus macrocephalus) is an important species, both economically and ecologically in the Bering Sea and Aleutian Islands (BSAI). However, little is known about its spawning dynamics. To address this knowledge gap, I developed a gross anatomical maturity key for Pacific cod to assess temporal and spatial patterns of reproductive maturity. Gross anatomical maturity keys estimate reproductive maturity by categorizing changes that occur in appearance of ovaries during maturation. Because maturity keys are based on characteristics that change on a continuum, stage assignment can be subjective particularly for ovaries in transition (displaying characteristics of more than one stage). Histological processing is often used to verify maturity key staging by estimating the maturity of individual oocytes from within assessed ovaries. I compared individual oocyte development through histological processing with gross anatomical stage assignments to evaluate the accuracy of Pacific cod maturity key using two approaches. First, assumptions made in delineating advancing characteristics between stages during the development of the key were analyzed by comparing oocyte development from ovaries assigned to key maturity stages by the researchers who designed the key. Secondly, the consistency in the use of the maturity key was addressed by comparing stage assignments to oocyte development for multiple data collectors employing the maturity key in the field. Misclassification rates for the key designers were 22% and field samplers using the key resulted in misclassification rates of 43%. While the misclassification rates are high, the mismatch between histological assessments and gross maturity was very narrow and most often assigned correctly to an adjacent stage. Misclassifications occur most often in the vitellogenin stages where criteria for delineating between stages both histologically and through the use maturity key are based on relative changes in size and color of the ovaries. By using morphological changes to track ovarian maturation, gross anatomical maturity keys provide an easily applied and inexpensive method for the collection of large quantities of data. Maturity data collected by observers aboard commercial fishing vessels in the BSAI were used to construct maps showing spawning sites along the continental shelves of the BSAI between the 100 and 200m isobaths. Spawning stage data for days where a high percentage of spawning was observed ("hot days") were mapped to show areas of high intensity spawning ("hot spots"). Hot spots were identified north of Unimak Island, in the vicinity of the Pribilof Islands, at the shelf break near Zhemchug Canyon, and adjacent to the central and western Aleutian Islands. Further analysis of spawning and spent stage data suggests spawning phenology was consistent during the three study years with varying climate conditions, though variation was seen in the duration of the spawning season among years and regions within years. While the processes determining the timing and location of spawning are poorly understood, knowledge of the above patterns allows further examination of how Pacific cod spawning correspond with environmental conditions throughout the season and between years of varying climate patterns. This work provides an initial description of the distribution and phenology of Pacific cod spawning along with a generalized description of oceanographic features observed at hot spot locations during the spawning season. / Graduation date: 2013