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NEXT STEPS AND SUGGESTIONS
Microtrolling has the potential to allow investigation of
subjects that until now have been overlooked in studies
of Salish Sea salmon survival, such as the condition,
habitat and survival of fish over the first winter in the
ocean. The results of Cowichan PIT tagging and acoustic
tagging studies have indicated that important mortality
occurs after the first summer at sea; the latter study (and
a number of studies in Puget Sound) have also indicated
considerable residence of Salish Sea Chinook Salmon
through at least the first winter at sea.
Ongoing and future studies at PSF using microtrolling will
allow us to economically sample juvenile Chinook Salmon
through their first winter in the Salish Sea, characterizing
over-winter habitat and assessing fish condition and
health and diet composition and quality. Microtrolling will
be used in a new study to PIT tag multiple stocks of East
Coast Vancouver Island Chinook Salmon during and after
their first winter at sea, to partition out the importance of
first winter mortality in regulating recruitment success of
Salish Sea Chinook Salmon.
Figure 5. Varying diets of microtroll-caught Chinook Salmon from Sansum Narrows and Maple Bay. Fish in Sansum Narrows were larger
and their diets contained a higher proportion of Pacific Herring, which also resulted in higher growth rates for these juvenile Chinook. Figure
provided by Will Duguid.
Figure 6. Will Duguid, UVic, who co-developed and used
microtrolling extensively for his PhD studies.
