| Summary: | The summer habitat of the southern resident population of killer whales (Orcinus
orca) in British Columbia and Washington experiences heavy traffic by vessels involved in
whale-watching, sport fishing, other recreational activities, and shipping. Behavioural
changes caused by vessel proximity and the impacts of vessel noise have been previously
documented, but this is the first study to assess direct impacts of air pollutant emissions from
vessel traffic. The concentration and composition of air pollutants from whale-watching
vessels that southern resident killer whales are exposed to during the peak tourist season were
estimated, as were the health impacts of the exposure. Specifically, the study a) estimated
the output of airborne pollutants from the whale-watching fleet based on emissions data from
regulatory agencies, b) estimated the vertical dispersion of such pollutants based on air
stability data collected in the field and from climatological sources, c) used a dispersion
model incorporating data on whale, vessel, and atmospheric behaviour to estimate exposure,
and d) examined the likely physiological consequences of this exposure based on allometric
extrapolation of data from other mammalian species. The results of these exercises indicate
that the current whale-watching guidelines are usually effective in limiting pollutant
exposure to levels just at or below those at which adverse health effects would be expected in
killer whales. However, under ‘worst-case’ conditions and even under certain ‘average-case’
conditions the pollutant levels are much higher than those predicted to cause adverse health
effects. With this information, recommendations are made for further studies that would fill
in missing information, and increase confidence in the models, and the predicted impact on
the southern resident killer whales. Recommendations for limiting killer whale exposure to
air pollutants are also provided.
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