Brad Hanson is a wildlife biologist with NOAA's Northwest Fisheries Science Center and one of the scientists most intimately acquainted with the decline of the Southern Resident Killer Whales (SRKW). After 15 years of studying them using satellite tags among other techniques, Hanson believes the SRKW are likely dying from disease not starvation, as has been widely publicized. He says they're likely more susceptible to pathogens because they don't have enough food to eat. The SRKW are not like other orcas who eat mammals and sharks. They only eat fish and they prefer Chinook salmon. Unfortunately, those fish are also disappearing. At the time of this recording, there are 75 SRKW left alive in the wild.