Data from the Surveyor 1968 Spring cruise were used to study the vertical distribution of salinity, temperature, dissolved oxygen, apparent oxygen utilization, pH, alkalinity, specific alkalinity and percent saturation of calcite in two sections, one along 162°W from 35°N to 45°N and the other along 180°W from 35°N to 50°N. Data from this cruise and additional data from the Surveyor 1968 Fall cruise, YALOC 66 cruise (summer) (Barstowetal, , 1968) and Boreas cruise (winter, 1966) (SIO reports, 1966) were used to study the distribution of salinity, temperature, apparent oxygen utilization, preformed phosphate and depth on the sigma-t surfaces of 26.8 and 27.3 in an area between 35°N and 52°N and 162°W and 155°E. In both sections the vertical distribution of the physico-chemical parameters is such that in general there is a tendency for the isograms to slope upward from south to north following the same trend of the sigma-t surfaces. This indicates that mixing and advection along the sigma-t surfaces play an important role on the distribution of these parameters. AOU data from YALOC 66 cruise (summer) compared to that from Surveyor 1968 Spring cruise suggest that aeration by mixing, eddy diffusivity and conductivity takes place to more than 500 meters depth at about 50°N. It also suggests that the changes of organic primary production at the euphotic zone during different seasons of the year may affect to a great extent the AOU distribution on the 26.8 sigma-t surface and to a very small extent on the 27.3 sigma-t surface. The direction of flow suggested by the AOU distribution on the 26.8 and 27.3 sigma-t surfaces was compared to that indicated by the acceleration potential contours on the S[subscript t] = 125 cl/ton and S[subscript t] = 80 cl/ton surfaces drawn by Reid (1965). The disagreements were explained in terms of mixing and possible gradients of primary production at the sea surface. On the 26.8 sigma-t surface a southward flow connecting the westward flow south of the Aleutian chain and the eastward flow farther south, between 175°E and 180°W is suggested by the AOU distribution but not by the acceleration potential contours. If the circulation pattern at this density surface is similar to that at the sea surface, this linkage is very likely to be real. / Graduation date: 1970

Using the hydrographic data collected by the ACONA from June 1961 to May 1963, the Oregon coastal front has been examined. Representative sigma-t surfaces were chosen to delineate the front, and changes in position of these surfaces with time were used to obtain zonal flow rates for the frontal and surface layers. From May to early October upwelling resulted in offshore flow. Onshore flow was indicated from late October to January, and indeterminate zonal flow occurred during the remainder of the year. Flow within the front agreed with these surface flows in ten of the fourteen observational periods. / Graduation date: 1964

This study investigated long-term (1961-2008) changes in albacore (Thunnus alalunga) abundance and distribution in relation to local environmental and large-scale climate indices in the Northeastern Pacific using time series and spatial analyses. Prior to the time series analysis, a wavelet analysis was conducted to examine nonrandom patterns of cyclical variability which revealed that monthly and annual time scales had the highest non-random variability. Thus, the time series analysis was done at these two scales using non-linear generalized additive models (GAMs) and threshold GAMs. At the monthly scale, sea surface temperature (SST) was found to be the variable with the strongest (positive) association to albacore catch per unit effort (CPUE). This association was likely driven by the seasonal migrations of juvenile albacore into and out of the U.S. coastal waters. At the yearly time scale over large geographical areas, the SST association broke down, and the scalar wind speed cubed (an indicator of mixed layer depth) at a five year lag became the dominant variable. The scalar wind speed cubed index explained 65% of the variability and was highly significant, even after adjusting for multiple tests (Bonferroni corrected P-value<0.001). These results suggest that a deeper mixed layer in the Northeastern Pacific may provide favorable foraging habitat for juvenile (mostly age 3) albacore, resulting in successful growth, spawning, and recruitment into the fishery in later years. This mixed layer depth association could help managers and stock assessment groups in their efforts to integrate environmental factors into the estimate of albacore population size. The spatial/spatio-temporal analyses involved modeling the CPUE with four competing GAM formulations, each representative of a different hypotheses for albacore distribution: 1) spatial, 2) spatial and environmental (SST, PDO, and MEI), 3) spatially variant, and 4) nonstationary, as indicated by the North Pacific regime shift of 1977. Results indicate that SST had a predominantly positive but spatially-variable effect on albacore CPUE, while the PDO had a negative overall effect. Specifically, CPUE was found to increase with increased SST, particularly off of Oregon and Washington. These results imply that if ocean temperatures continue to increase, west coast communities reliant on commercial albacore fisheries are likely to be negatively impacted in the southern areas but positively benefited in the northern areas, where current albacore landings are highest. / Graduation date: 2012

Recent studies have identified the North Pacific Gyre Oscillation (NPGO) as a decadal mode of climate variability that is linked to previously unexplained fluctuations of salinity, nutrient, and chlorophyll in the Northeast Pacific. The NPGO reflects changes in strength of the central and eastern branches of the subtropical gyre and is driven by the atmosphere through the North Pacific Oscillation (NPO) -the second dominant mode of sea level pressure variability. We show that Rossby waves dynamics excited by the NPO propagate the NPGO signature from the central North Pacific into the Kuroshio-Oyashio Extension (KOE), and trigger changes in strength of the KOE with a lag of 3 years. This suggests that the NPGO index can be used to track changes in the entire northern branch of the North Pacific sub-tropical gyre. These results also provide a physical mechanism to explain coherent decadal climate variations and ecosystem changes between the North Pacific eastern and western boundaries.

Typescript (photocopy) / Bibliography: leaves 127-131. / Microfiche. / xii, 131 leaves, bound ill. 29 cm

Thesis (Ph. D.)--Oregon State University, 1991. / Includes mounted photographs. Typescript (photocopy). Includes bibliographical references (leaves 112-119). Also available on the World Wide Web.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references. Content: Patterns of development in nudibranch mollusks from the northeast Pacific Ocean, with regional comparisons. -- Lecithotrophic development in Doto amyra (Nudibranchia: dendronotacea), with a review of development in the genus. -- Unusually large polar bodies in an aeolid nudibranch, a novel mechanism for producing extra-embryonic yolk reserves. xiv, 237 leaves : ill. ; 29 cm. / Biogeographic patterns of developmental mode in marine invertebrates have been examined with respect to latitude, depth, and general habitat type. Regional comparisons, which might reveal the influence of specific ecological mechanisms on mode of development, are few. The present study was undertaken to: 1) characterize early development, especially its mode, in nudibranch molluscs from the cold temperate waters of the northeast Pacific Ocean: 2) compare the development of these species to that of nudibranchs from other geographic regions: and 3) attempt to explain the observed patterns on the basis of regional differences in hydrography, geology, and primary production. Observations of egg size, embryonic development and hatching larvae were made for 30 species and were supplemented with data from the literature. All data for other regions were obtained from the literature. Developmental mode was determined for 69 NE Pacific species, over half the known fauna. sixty-seven (97%) have planktotrophic development and two (Doto amyra and the introduced Tenellia adspersa) produce short-term lecithotrophic larvae. No evidence for nurse-eggs was obtained in this study, and only the egg capsules of the aeolid Cuthona lagunae were found to contain extra-zygotic yolk reserves. These took the novel form of unusually large, yolk-filled polar bodies that were ingested by the embryonic veligers. Planktotrophic species with egg-shaped, inflated larval shells develop from larger eggs than those of species with typical spiral shells. The former, however, have shorter embryonic periods, owing, in part, to their smaller egg masses; many also hatch with eyespots. World-wide I conclude that planktotrophy, at least among nudibranchs, is most common in regions with relatively slow currents, high standing stocks of phytoplankton, and large expanses of habitat suitable for the adults. This is documented by evidence from the NE Pacific, NE u.s., Britain, NW Red Sea, and NW Mediterranean. Nonfeeding modes of development tend to predominate in areas with fast boundary currents, oligotrophic waters, rapid changes in physical aspects of the adult environment, or in areas formerly in contact with polar waters (e.g., SE U.S., Marshall Is., New South Wales). Latitude and its correlates do not sufficiently account for the observed regional differences in mode of development.

The North Pacific humpback whale (Megaptera novaeangliae) is a wide-ranging baleen whale species with a complex life history and population structure. As seasonal migrants, humpback whales are known to inhabit cooler, high-latitude waters when foraging and low-latitudes for mating and calving. Beyond this general migratory pattern, a number of demographic characteristics including, abundance, distribution, seasonal occurrence, and prey preferences remain unknown or poorly described. A complete understanding of humpback whale ecology is therefore lacking. Many methods used to explore these aspects of cetacean ecology are either prohibitively expensive or limited in the scope of what can be learned from their use. Fortunately, in recent years, the analysis of stable isotope ratios of animal tissues has proved a valuable and relatively inexpensive technique for providing information on trophic position, diet, and feeding origins of migratory populations. This study employed techniques in stable isotope ecology to increase knowledge of the population structure, migration routes, and foraging ecology of North Pacific humpback whales. Skin samples were collected from free-ranging humpback whales throughout all known feeding and breeding grounds and were analyzed for stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope ratios. The population structure of humpback whales was first explored through geographic differences in stable isotope ratios. Stable isotope ratios varied significantly with location of sample collection. Based on this analysis, foraging animals were separated into six feeding groups. Classification tree analysis was then used to determine which isotopic variables could be used to predict group membership. Probable migratory linkages were then described by applying results of classification trees to [delta]13C and [delta]15N of animals sampled on breeding grounds. Strong migratory connections between the eastern-most foraging and breeding areas and the western-most areas were reflected in similarities of stable isotope ratios. Foraging ecology was then examined through calculation and comparison of the relative trophic levels of the six feeding groups. Isotopic values suggest some feeding groups are piscivorous, while others feed on a more mixed diet. These results can be used to determine if differences in diet composition between groups result in differences in accrued nutritional benefits, negatively impacting reproductive success and survival relative to fish eating groups. Finally, to gain insight into specific foraging habits, the diet of one group of humpback whales was modeled using an isotope mixing model. The [delta]13C and [delta]15N of Kodiak Island, Alaska humpback whales and several species of potential prey indicate that these animals likely rely heavily on euphausiids (Thysanoessa spinifera), Pacific sandlance (Ammodytes hexapterus), and capelin (Mallotus villosus). This study represents the first application of stable isotope ecology to an entire population of marine mammals. Stable isotope analysis was successfully applied to describe and improve understanding of the demographics of North Pacific humpback whales.

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

Tropical and extratropical Pacific decadal climate variability substantially impact physical and biological systems in the Pacific Ocean and strongly influence global climate through teleconnection patterns. Current understanding of Pacific decadal climate variability centers around the El Niño-Southern Oscillation (ENSO), the Aleutian Low (AL), and the Pacific Decadal Oscillation (PDO). However, recent literature has highlighted the emerging roles of secondary modes of variability of the tropical and extratropical Pacific atmosphere and ocean in global climate change: the Central Pacific Warming (CPW) phenomenon, the North Pacific Oscillation (NPO), and the North Pacific Gyre Oscillation (NPGO). This work analyzes the statistics and uncertainties behind Pacific interannual and decadal-scale climate variability, and focuses on better understanding the roles of the CPW, NPO, and NPGO in the climate system. The study begins by examining the dynamics of the NPO and its role in Pacific interannual and decadal climate variability. Results illustrate that the individual poles of the NPO have relations at high frequencies, but only the southern node contains a deterministic low-frequency component, which is forced by tropical Pacific sea surface temperature (SST) variability, as shown with a modeling experiment. The NPO-induced variability by the tropical Pacific SST is then integrated by the underlying ocean surface to form the decadal-scale NPGO signal. Thus, a new link between the CPW, the NPO, and the NPGO is formed, expanding the current framework of Pacific decadal variability and its implications for weather and climate. The new framework of North Pacific decadal variability (NPDV) is then evaluated in 24 state-of-the-art coupled climate models. Results indicate that the models in general have difficulty reproducing the leading modes of NPDV in space and time, particularly the NPGO mode and its connection to the NPO. Furthermore, most models lack the proper connections between extratropical and tropical Pacific, for both the ENSO/AL/PDO and CPW/NPO/NPGO connections. Improvements in these teleconnections are thus needed to increase confidence in future climate projections. The last part of the dissertation explores further the importance of the CPW mode by comparing and contrasting two popular paleoclimate SST anomaly reconstruction methods used for tropical Indo-Pacific SSTs. The first method exploits the high correlation between the canonical ENSO mode and tropical precipitation; the second method uses a multi-regression model that exploits the multiple modes of covariability between tropical precipitation and SSTs, including the CPW mode. The multi-regression approach demonstrates higher skill throughout the tropical Indo-Pacific than the first approach, illustrating the importance of including the CPW phenomenon in understanding past climates.