A new count of gray whales that migrate along the West Coast each year found a continued decline of this population. However, new clues suggest that population numbers may soon start to rebound.
The decline is thought to be connected, at least in part, to shifts in the distribution and abundance of prey that gray whales feed on during summer months spent in the Arctic. However, scientists have made other observations over the last several months at wintering lagoons in Mexico and along the U.S. West Coast. They suggest that small shifts in some trends may offer reason for optimism:
- The body condition of gray whales in the lagoons in Baja California, Mexico improved in 2023
- Fewer whales died and stranded in Mexico this year than in any year since the UME started in 2019
- Whales in the lagoons have increased in number, with biologists counting more mothers with calves in 2023 than any of the last 5 years
- Fewer gray whales have stranded along the West Coast during their northward migration this year than during the peak years of the Unusual Mortality Event
Mexican researchers reported their observations from 2023 to the International Whaling Commission earlier this year, said Dr. Jorge Urbán Ramírez, a professor at the Autonomous University of Baja California Sur who leads gray whale research in Mexico. He said the reduced strandings this year suggest “the gray whale mortality event may be slowing.”
Calf Numbers Signal Possible Reproductive Success
“Following the decline in numbers of stranded whales and improvements in body condition, the next step toward recovery of the population would be increased reproductive success,” said Dr. Aimée Lang, a research biologist at the Southwest Fisheries Science Center who helped lead this years’ gray whale count. “The reports of small increases in the number of calves in Mexico may be a promising sign.”
Biologists with the center just recently finished counting gray whale calves migrating north with their mothers along the California Coast this year. They expect to report the results in a few months and are hopeful that they will reflect a similar trend to that seen in the Mexican lagoons.
The center typically conducts its gray whale population counts during the southbound migration on a cycle of two out of every five years. However, an additional count was conducted this year and another count will be conducted in the winter of 2024 to track the gray whale population trajectory. The gray whale population rebounded following a previous UME from 1999 to 2000 surging to peak numbers in 2016.
“We continue to monitor the population closely,” said Dr. David Weller, Director of the center’s Marine Mammal and Turtle Division. “We want to pick up on any signs or signals of a positive change in the concerning trend the population has undergone recently.”
An Unusual Mortality Event
NOAA Fisheries declared an Unusual Mortality Event (UME) for the eastern North Pacific gray whale population in 2019 amid a surge of gray whale strandings. The population estimates have since declined from a peak of around 27,000 whales in 2016 to approximately 14,500 in 2023.
This new estimate is roughly comparable to the number of gray whales when counts first began in the late 1960s. The species at that time was recovering from the commercial whaling era. As numbers grew, gray whales were removed from Endangered Species Act protection in 1994.
Research teams are continuing to investigate the factors contributing to the UME.
