Marine
Survival of Juvenile Coho Salmon
Marine
Survival of Juvenile Coho Salmon Research led by Prof Carl Walters and Michael
Melnychuk of the University of British Columbia is aimed to study what is happening
during juvenile coho salmon’s early life in marine waters.
Coho salmon
stocks declined dramatically in the 1990s throughout South-western British Columbia
and the U.S. Pacific Northwest. It is widely suspected among salmon biologists
that a large part of marine mortality occurs in the first few weeks of ocean life
in coastal areas, as juveniles are highly susceptible to predation during this
phase. Where and how they spend their time in the first couple of weeks of ocean
life is likely to have major implications for marine survival.
The
UBC researchers tracked the movements of tagged juvenile salmon in Howe Sound,
B.C. using a directional hydrophone and acoustic receiver on their research vessel.
They could often use telemetry to slowly approach a tag dead-on, and then use
the Interphase PC/180 sonar system to view the immediate area surrounding the
detected tags. Using this sampling technique, they would look for targets indicating
salmon or the presence of larger fish or marine mammals in the area that might
be predators of juvenile salmon.
Tracking
juvenile salmon in the Squamish River estuary proved to be a difficult task. Depths
would often be off with as much as 30 feet from charted depths due to sedimentation;
the forward looking capability of PC/180 however made the study possible. "We
would not have been able to operate on the tidal flats and in the estuary without
the PC/180" says the skipper, Villy Christensen.
The
preliminary study clearly demonstrates a potential for using sonar systems such
as the PC/180 in conjunction with hydroacoustic telemetry to study the behavior
of juvenile salmon in marine waters. Read more about the salmon research |
Harbour seals accounted
for 20% of the juvenile salmon mortality
Studying salmon behavior
using PC/180
|
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