Gregory T. Ruggerone

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Annual hatchery production rates of chinook (Oncorhynchus tshawytscha), coho (0. kisutch) , sockeye (0. nerka) , pink (0. gorbuscha) , chum (0. keta), masu (0. masu} salmon, and steelhead trout (0. mykiss} were obtained from published and unpublished sources and compiled as a computer database. Pacific Rim hatchery production trends for the 40-year period(More)
The hypothesis that growth in Pacific salmon Oncorhynchus spp. is dependent on previous growth was tested using annual scale growth measurements of wild Chinook salmon Oncorhynchus tshawytscha returning to the Yukon and Kuskokwim Rivers, Alaska, from 1964 to 2004. First-year marine growth in individual O. tshawytscha was significantly correlated with growth(More)
Well-functioning food webs are fundamental for sustaining rivers as ecosystems and maintaining associated aquatic and terrestrial communities. The current emphasis on restoring habitat structure--without explicitly considering food webs--has been less successful than hoped in terms of enhancing the status of targeted species and often overlooks important(More)
Relatively little is known about fish species interactions in offshore areas of the world’s oceans because adequate experimental controls are typically unavailable in such vast areas. However, pink salmon (Oncorhynchus gorbuscha) are numerous and have an alternating-year pattern of abundance that provides a natural experimental control to test for(More)
Can variation in prey density drive changes in the intensity or direction of selective predation in natural systems? Despite ample evidence of density-dependent selection, the influence of prey density on predatory selection patterns has seldom been investigated empirically. We used 20 years of field data on brown bears (Ursus arctos) foraging on sockeye(More)
Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap in the ocean, and wild salmon populations having low productivity may compete for food with abundant(More)
The metacommunity concept has recently been described to account for the roles of dispersal in regulating community structure. Despite its strong theoretical basis, there exist few large-scale and long-term examples of its applicability in aquatic ecosystems. In this study we used a long-term dataset (1961–2007) on the relative abundances of the dominant(More)
Gastric evacuation of multiple meals of recently emerged sockeye salmon, Oncorhynchus nerka, consumed by juvenile coho salmon, O. kisutch, were compared with that expected from a single meal evacuation rate model developed for the estimation of food consumption by coho in the field. Significant interaction occurred between meals consumed two hours apart(More)
Climate, competition, and disease are well-recognized drivers of population dynamics. These stressors can be intertwined by animal migrations, leading to uncertainty about the roles of natural and anthropogenic factors in conservation and resource management. We quantitatively assessed the four leading hypotheses for an enigmatic long-term decline in(More)
In the warming Arctic, aquatic habitats are in flux and salmon are exploring their options. Adult Pacific salmon, including sockeye (Oncorhynchus nerka), coho (O. kisutch), Chinook (O. tshawytscha), pink (O. gorbuscha) and chum (O. keta) have been captured throughout the Arctic. Pink and chum salmon are the most common species found in the Arctic today.(More)