Southern Resident orcas depend heavily on Chinook salmon, which are big, fatty, and energy-rich. Dams on rivers like the Columbia and Snake interfere with salmon at multiple life stages:

  • Block access to spawning grounds
  • Kill or weaken juvenilesas they pass through turbines orreservoirs
  • Slow river flow, making migration longer and more dangerous
  • Warm the water, which stresses salmon and increases disease

Even with fish ladders, survival rates are much lower than in free-flowing rivers

Less salmon = hungry orcas

When Chinook numbers drop:

  • Orcas must spend more time and energy hunting
  • They burn stored fat, releasing toxins(PCBs, etc.) into their bloodstream
  • Females are less likely to get pregnant
  • Calves are more likely to be miscarried or die young

Internet search/ Paul Clark