Ochre Sea Stars Rebound on Oregon Coast After Decade-Long Decline

After more than a decade of steep losses, ochre sea stars along the Oregon and northern California coasts are showing encouraging signs of recovery, according to a long-term study by researchers at Oregon State University and Cal Poly San Luis Obispo published in the journal Ecosphere.

Juvenile Surge Fuels Comeback

The team documents a dramatic surge in juveniles — an 8,000% increase in young ochre sea stars landing on shore after population crashes — which has helped counts rebound at many sites. The study is based on 23 years of monitoring at eight locations along the Oregon Coast.

Background: Sea Star Wasting Syndrome

The recovery follows a devastating outbreak of sea star wasting disease (often called Sea Star Wasting Syndrome) first observed in 2013. The disease spread from Mexico to Alaska and produced lesions, twisted and deteriorating arms, and widespread die-offs. Researchers estimate it killed between 59% and 84% of ochre sea stars along the Oregon Coast.

“Wasting disease remains in circulation and populations continue to fluctuate, but there’s also much evidence that ochre sea stars are bouncing back,” said Sarah Gravem, the study’s lead author.

Ecological Impact and Remaining Challenges

At roughly three-quarters of the study sites, ochre sea stars have reached densities and sizes sufficient to resume their role as a keystone predator: predation on California mussels has largely returned. As Bruce Menge, a distinguished professor of integrative biology at OSU, noted, the sea stars are eating mussels at rates similar to pre-epidemic levels at most sites.

However, recovery is not complete. Average body sizes remain about 25–65% smaller than before the die-off, and population counts are still more variable year to year than in pre-2013 surveys. The researchers emphasize that wasting disease persists regionally and populations continue to fluctuate.

Unanswered Questions

The study does not conclusively link the juvenile boom to the earlier epidemic. Gravem and colleagues say the timing could indicate resilience (if the boom is a response to the die-off) or could be coincidental — the result of favorable environmental conditions or chance. Continued monitoring and research will be needed to understand drivers of recovery and long-term stability.

Study details: Lead author Sarah Gravem began the project as a postdoctoral researcher at OSU and is now an assistant professor at Cal Poly San Luis Obispo. She collaborated with Bruce Menge and other colleagues to analyze long-term data from eight intertidal sites over 23 years.

These findings offer cautious optimism: while challenges remain, ochre sea stars appear on a path toward partial recovery, with meaningful implications for intertidal community structure and resilience to future mass-mortality events.