Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Fraser River do so via this route. However, when warmer conditions prevail, migration
patterns shift to the north through the Johnstone Strait (Groot and Quinn 1987).
Climate Change
Anthropogenic climate change, caused by factors such as the continuing build-up of
human-produced atmospheric carbon dioxide, is predicted to have major environmental
impacts along the west coast of North America during the 21 st century and beyond (IPCC
2001; CIG 2004). Warming trends continue in both water and air temperatures.
Projections of the consequences of climate change include disruption of annual cycles of
rain and snow, alteration of prevailing patterns of winds and ocean currents, and
increases in sea levels (Glick 2005; Snover, Mote et al. 2005). Oceanographic models
project a weakening of the thermohaline circulation resulting in a reduction of heat
transport into high latitudes of Europe, an increase in the mass of the Antarctic ice sheet,
and a decrease in the Greenland ice sheet (IPCC 2001). These changes, coupled with
increased acidification of ocean waters, are expected to have substantial effects on marine
productivity and food webs, including populations of salmon and other salmonid prey
(Hard, Jones et al. 1992).
Climate change poses significant hazards to the survival and recovery of salmonids along
the west coast. Changes in water temperature can alter migration timing, reduce growth,
reduce the supply of available oxygen in the water, reduce insect availability as prey, and
increase the susceptibility of fish to toxicants, parasites, and disease (Fresh, Casillas et
al. 2005; NMFS 2007). Earlier spring runoff and lower summer flows make it difficult
for returning adult salmon to negotiate obstacles (NMFS 2007). Excessively high levels
of winter flooding can scour eggs from their nests in the stream beds and increase
mortalities among overwintering juvenile salmon. The predicted increased winter
flooding, decreased summer and fall stream flows, and elevated warm season
temperatures in the streams and estuaries may further degrade conditions for salmon that
are already stressed from habitat degradation. Although the impacts of global climate
change are less clear in the ocean environment, early modeling efforts suggest that
increased temperatures will likely increase ocean stratification. This stratification
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