UBC Theses and Dissertations
A compilation and meta-analysis of salmon diet data from the North Pacific Ocean Graham, Caroline
Salmon migrate thousands of kilometers through dynamic ecosystems of the North Pacific Ocean, however, their open ocean life phase is poorly understood with limited research comparing salmon trophic ecology across the entire basin. Understanding the marine trophic ecology of salmon has the potential to reveal information about ocean conditions, competition, prey abundance, as well as salmon health and survival. The first goal of this research was to build an open-access database to centralize Pacific salmon diet data using a standardized format (‘North Pacific Marine Salmon Diet Database’). This database was then populated with an initial data set that came from 62 sources identified through a systematic literature review, targeting peer reviewed and gray literature from time periods with high research activity: 1959–1969 and 1987–1997. The second goal was to examine spatial and interspecies differences in diet and trophic niche for chum, pink and sockeye salmon across the North Pacific between 1959 and 1969, a period during a negative phase of the Pacific Decadal Oscillation and prior to significant hatchery enhancement. In the Western Subarctic, all species tended to consume zooplankton and prey availability was higher than the Eastern Subarctic. In the Gulf of Alaska and Eastern Subarctic, interspecies differences in diet were most apparent with chum and sockeye specializing on zooplankton and micronekton, respectively, while pink ate a mixture of zooplankton and micronekton. In the Bering Sea chum ate zooplankton while sockeye and pink alternated between zooplankton and micronekton. In addition to the large-scale trophic patterns, these data revealed novel fine-scale spatial trophic patterns, including latitudinal, onshore-offshore, and cross-gyre gradients. These results showed that pink were more generalist consumers, and their diets may be a better reflection of overall prey presence and abundance in the environment. Conversely, chum and sockeye were more specialist consumers, and their diets may be a better reflection of interspecies dynamics and/or specific prey presence and abundance of zooplankton and micronekton, respectively. Overall, this research provides an open-access database that can help address gaps in ecological understanding of the North Pacific, as well as complementary data analyses to further understanding of salmon marine ecology.
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