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Summary:
Pacific salmon, an important natural,
economic, social and cultural resource for Canada has been declining during
the last few decades, which might be linked to changes in freshwater and
ocean conditions and associated changes in growth and survival of juveniles.
However, it is still not fully understood what specific processes and how
they are linked to growth and size-distribution of juvenile Pacific salmon,
and their implications for adult returns and recruitments. The proposed
5-year research program addresses the following fundamental questions
related to the ecology of juvenile Pacific salmon in freshwater and marine
ecosystems: 1) what major
processes determine the size and age distribution of sockeye fry and smolts
among non-glacial, glacial and colored lakes with variable nutrients and
foodweb structure; 2) how do cohabiting zooplanktivorous fish and
invertebrates in sockeye lakes affect the size and age distribution of
sockeye fry through foodweb interaction and resource partitioning; and 3)
once the smolts of variable ages and sizes of Pacific salmon enter the
common feeding grounds of the coastal north Pacific Ocean, how do the
foodweb dynamics and trophic interactions within and among juveniles of
different species vary inter-annually as a function of body size in their
onshore and offshore habitats. The 1st objective uses comparative
analyses of limnological and fisheries data from a large number of sockeye
lakes in Alaska, and the 2nd and 3rd objectives apply
stable isotope geochemistry to delineate foodweb dynamics and trophic
interactions within and among species using sockeye lakes in BC and the
eastern Bering Sea Ecosystem. We
hypothesized that variable lake or ocean conditions through shifts in the
quality and quantity of prey may affect foodweb dynamics, trophic
interactions and diet overlaps within and among species as a function of
size, and eventually the growth and survival of juvenile Pacific salmon.
This research program is
expected to produce new insights and better understanding of foodweb
dynamics and trophic interactions of juvenile Pacific salmon, which will
lead to better management strategies for one of Canada’s precious natural
resources, the Pacific salmon.
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