One in Five Gray Whales Die in San Francisco Bay
Gray whales usually migrate between the Arctic and Mexico. But climate change is altering their path. Some now enter San Francisco Bay. Sadly, nearly one in five dies there. Researchers tracked 114 individual whales between 2018 and 2025.
Ship Strikes and Starvation
The Bay is busy with boat traffic. Fog makes the whales hard to see. As a result, vessel strikes are a major threat. Over 40 percent of local strandings showed trauma from ships. Many other whales also showed signs of malnutrition. Weakened animals may struggle to avoid boats.
Emergency Feeding Stop
Gray whales rarely feed during migration. However, warming Arctic waters disrupt their usual food supply. Therefore, some turn to the Bay as an emergency stop. These whales are often in poor condition. Nevertheless, only four individuals returned in later years. High mortality likely explains this low number.
A Growing Crisis
Since 2016, gray whale numbers have dropped by more than half. Calves are rarely seen. In 2025 alone, 36 whales entered the Bay. Sometimes more than ten arrived together. “At least 18 percent of identified whales later died in the area,” says lead author Josephine Slaathaug.
Potential Solutions
Route changes and speed restrictions can reduce vessel strikes. Education programs for operators may also help. Continued monitoring will reveal whale behavior patterns. This information can protect the species. The findings show a population struggling to adapt to climate change in real time.
