Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population
Figure 3
Nutrition correlates with sex, year and Julian date.
Nutritional status, indexed by fecal triiodothyronine concentrations, is highest when the southern resident killer whales return to the Salish Sea in the spring and declines throughout the summer into the fall and winter. The y-axis represents triiodothyronine concentration marginal means predicted from the best-fit mixed effects model after controlling for individual and sex. The hashed blue lines indicate 95% confidence intervals. Vertical red dotted lines indicate Julian day 230 (August 18), the time of maximum vessel traffic and ten days before maximal Fraser River Chinook salmon catch each year. Horizontal red dotted lines indicate dependent variable marginal means for each year on day 230 within the model.