Body size, mediated through biotic and abiotic factors affecting growth, is fundamental in determining survival as larger animals are usually less vulnerable to predation, starvation, and extreme environmental conditions (Peterson & Wroblewski 1984; Sogard 1997). Size-selective mortality is a prevalent force regulating marine survival for many anadromous salmonid species, including ESA-listed Chinook salmon (Oncorhynchus tshawytscha) in Puget Sound, WA. The “critical size – critical period” hypothesis suggests that marine survival of anadromous Pacific Salmon (Oncorhynchus spp.) is controlled by two size-selective survival bottlenecks – one during the first marine summer and another during the first marine winter (Beamish and Mahnken 2001). Previous research has indicated a strong positive relationship between the size of juvenile ESA-listed Chinook salmon (O. tshawytscha) in Puget Sound and their survival to adulthood, indicating that early marine growth drives survival (Duffy 2009). Before investigating the drivers of early marine growth, however, it is imperative to understand whether size-selective mortality occurs prior to July in Puget Sound. If so, we may be able to augment marine survival by directing conservation and restoration efforts toward the habitats or regions of Puget Sound where size-selective mortality occurs. Additionally, we must account for any size-selective mortality in estimating early marine growth, as observed weight in July would reflect an artificially inflated “apparent” growth if smaller individuals were experiencing disproportionately high mortality. In this study, we repeatedly sampled nine stocks of both wild and hatchery-origin sub-yearling Chinook salmon during their outmigration into and rearing in Puget Sound. We used scale morphometrics to determine if size-selective mortality is affecting sub-yearling Chinook salmon during their first marine summer rearing in Puget Sound, and if so, where and when that size-selective mortality occurs. We found no evidence of size-selective mortality occurring between habitats or between sampling periods within habitats, suggesting that weight of juvenile Chinook as measured in July is representative of early marine growth and that size-selective mortality occurs later in the summer or outside Puget Sound during the first marine winter. We then focused on understanding differences in growth rates across time, among habitats, and among stocks of juvenile Chinook salmon, and used bioenergetic models to determine the relative influence of prey quality, prey availability, and temperature on early marine growth rates We found that sub-yearling Chinook were larger and grew faster in offshore than in nearshore habitats, and that this difference in growth rate was likely due to differences in prey availability and may have been exacerbated by higher nearshore temperatures. The results of this study can be used to direct restoration and conservation efforts aimed at supporting early marine growth of juvenile Chinook in Puget Sound, and can augment our understanding of distribution patterns and feeding behaviors of Pacific salmon during critical growth periods.

Evidence suggests that the variability in recruitment of adult Pacific salmon is related to smolt survival during the first ocean year. Specifically, the first few weeks and first marine winter may be two critical periods of high mortality during early marine life. Mortality during early marine residency has been attributed to predation and size-dependent factors while high mortality during the first winter may be due to energy deficits and failure to reach a certain size by the end of the growing season. My study assessed factors influencing overwinter mortality and early marine growth in juvenile Chinook salmon (Oncorhynchus tshawytscha) from Marble River, Quatsino Sound, British Columbia. Juvenile salmon were collected during November 2005 and 2006 (fall) and March 2006 and 2007(winter). Mortality rates over the first winter derived from catch per unit effort across seasons ranged between 80-90% in all years. These are the first estimations of overwinter mortality in juvenile Pacific salmon. Fish size distributions showed no evidence of size-selective overwinter mortality between fall and winter fish in either 2005-2006 or 2006-2007. Otolith microstructure analyses showed no significant difference in circulus increment widths during the first four weeks after marine entry. Similarities in increment width indicated that early marine growth did not differ between fall and winter fish during early marine residency in 2006. These observations show that the high overwinter mortality rates of juvenile Chinook salmon in Quatsino Sound are not size-dependent. Total plankton biomass was significantly lower in the winter season but size distribution, gut fullness and energy density data did not show evidence of starvation. No correlation was found between early marine growth, size, energy accumulation and high mortality in Marble River juvenile Chinook salmon during their first ocean winter in Quatsino Sound. Possible factors influencing these high mortality rates may include non size-selective predation, disease, local environmental influences or an as yet unknown source. Future work should continue to focus on understanding the relationship between early marine survival and adult recruitment. The expansion of growth comparisons geographically and chronologically while determining the effects of predatory mortality on juvenile Chinook salmon along the north Pacific continental shelf and beyond are imperative to fully understanding this complex marine life stage.

The salmon that symbolize the Pacific Northwest's natural splendor are now threatened with extinction across much of their ancestral range. In studying the natural and human forces that shape the rivers and mountains of that region, geologist David Montgomery has learned to see the evolution and near-extinction of the salmon as a story of changing landscapes. Montgomery shows how a succession of historical experiences -first in the United Kingdom, then in New England, and now in the Pacific Northwest -repeat a disheartening story in which overfishing and sweeping changes to rivers and seas render the world inhospitable to salmon. In King of Fish , Montgomery traces the human impacts on salmon over the last thousand years and examines the implications both for salmon recovery efforts and for the more general problem of human impacts on the natural world. What does it say for the long-term prospects of the world's many endangered species if one of the most prosperous regions of the richest country on earth cannot accommodate its icon species? All too aware of the possible bleak outcome for the salmon, King of Fish concludes with provocative recommendations for reinventing the ways in which we make environmental decisions about land, water, and fish.

"Fundamentally, the salmon's decline has been the consequence of a vision based on flawed assumptions and unchallenged myths.... We assumed we could control the biological productivity of salmon and 'improve' upon natural processes that we didn't even try to understand. We assumed we could have salmon without rivers." --from the introduction From a mountain top where an eagle carries a salmon carcass to feed its young to the distant oceanic waters of the California current and the Alaskan Gyre, salmon have penetrated the Northwest to an extent unmatched by any other animal. Since the turn of the twentieth century, the natural productivity of salmon in Oregon, Washington, California, and Idaho has declined by eighty percent. The decline of Pacific salmon to the brink of extinction is a clear sign of serious problems in the region. In Salmon Without Rivers, fisheries biologist Jim Lichatowich offers an eye-opening look at the roots and evolution of the salmon crisis in the Pacific Northwest. He describes the multitude of factors over the past century and a half that have led to the salmon's decline, and examines in depth the abject failure of restoration efforts that have focused almost exclusively on hatcheries to return salmon stocks to healthy levels without addressing the underlying causes of the decline. The book: describes the evolutionary history of the salmon along with the geologic history of the Pacific Northwest over the past 40 million years considers the indigenous cultures of the region, and the emergence of salmon-based economies that survived for thousands of years examines the rapid transformation of the region following the arrival of Europeans presents the history of efforts to protect and restore the salmon offers a critical assessment of why restoration efforts have failed Throughout, Lichatowich argues that the dominant worldview of our society -- a worldview that denies connections between humans and the natural world -- has created the conflict and controversy that characterize the recent history of salmon; unless that worldview is challenged and changed, there is little hope for recovery. Salmon Without Rivers exposes the myths that have guided recent human-salmon interactions. It clearly explains the difficult choices facing the citizens of the region, and provides unique insight into one of the most tragic chapters in our nation's environmental history.

Pacific salmon are an important biological and economic resource of countries of the North Pacific rim. They are also a unique group of fish possessing unusually complex life histories. There are seven species of Pacific salmon, five occurring on both the North American and Asian continents (sockeye, pink, chum, chinook, and coho) and two (masu and amago) only in Asia. The life cycle of the Pacific salmon begins in the autumn when the adult female deposits eggs that are fertilized in gravel beds in rivers or lakes. The young emerge from the gravel the following spring and will either migrate immediately to salt water or spend one or more years in a river or lake before migrating. Migrations in the ocean are extensive during the feeding and growing phase, covering thousands of kilometres. After one or more years the maturing adults find their way back to their home river, returning to their ancestral breeding grounds to spawn. They die after spawning and the eggs in the gravel signify a new cycle. Upon this theme Pacific salmon have developed many variations, both between as well as within species. Pacific Salmon Life Histories provides detailed descriptions of the different life phases through which each of the seven species passes. Each chapter is written by a scientist who has spent years studying and observing a particular species of salmon. Some of the topics covered are geographic distribution, transplants, freshwater life, ocean life, development, growth, feeding, diet, migration, and spawning behaviour. The text is richly supplemented by numerous maps, illustrations, colour plates, and tables and there is a detailed general index, as well as a useful geographical index.