The
consequences of exposure to
engine exhaust from whale-watching
vessels on the conservation
of the southern resident population
of killer whales (Orcinus
orca)
From
1996 to 2001, the southern
resident population of killer
whales (Orcinus orca) along
British Columbia’s coast declined
by 20% (Krahn et al. 2001).
Accordingly, this population
was listed as Endangered under
the Canadian Species at Risk
Act in 2001 and as Endangered
under the United States Endangered
Species Act in 2006. Three
anthropogenic factors have
been identified as possible
causes for this population
decline: decreased food availability
due to the decline of salmon
stocks, exposure to toxic
chemicals such as polychlorinated
biphenyls (PCBs), and chronic
boat disturbance (Bain 2002).
The
core habitat of the southern
resident killer whales is
easily accessible by commercial
and recreational whale watching
boats. The number of vessels
engaged in viewing this population
peaks during the six months
of summer, and the whales
are followed for approximately
12 hours per day (Trites &
Bain 2000). Exhaust pollutants
such as carbon monoxide, nitrogen
oxides, polycyclic aromatic
hydrocarbons, and particulate
matter are heavier than air,
and tend to accumulate at
the water’s surface where
the whales breathe. This undoubtedly
exposes them to higher levels
of air contaminants than they
would otherwise encounter.
My
proposed study will evaluate
the quantities of airborne
pollutants from whale watching
vessels inhaled by killer
whales, and will estimate
the physiological consequences
of this exposure. If these
consequences are found to
be severe, or potentially
severe, the study will include
specific conservation recommendations
and may serve as the basis
for regulatory changes in
the way that whale watching
is conducted.
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