A groundbreaking study has revealed that sea otters are playing an unexpected role in controlling invasive European green crabs along the California coast, offering a potential natural solution to a growing environmental challenge.
Research conducted at Elkhorn Slough in Monterey Bay shows that areas with higher sea otter populations have notably lower numbers of invasive green crabs. According to estuary ecologist Dr. Rikke Jeppesen, the current otter population of 100-120 animals in the slough can consume between 50,000 to 120,000 green crabs annually.
The European green crab, which was accidentally introduced to San Francisco Bay in the late 1980s, has spread rapidly along the West Coast, threatening native species and causing coastal communities to spend millions on control efforts. However, the return of sea otters to Elkhorn Slough has coincided with a dramatic decrease in the invasive crab population.
Dr. Kerstin Wasson, research coordinator at Elkhorn Slough, notes that spatial mapping clearly shows areas with high otter presence have reduced green crab numbers. This natural predator-prey relationship suggests that reintroducing otters to other affected coastal areas could help manage the invasive species while promoting healthier seagrass beds and salt marshes.
The findings come as various groups advocate for the reintroduction of sea otters to areas where they were eliminated by fur hunters over a century ago. While such programs would require substantial investment and may face resistance from fishing industries, researchers emphasize the need to explore natural solutions for ecosystem management.
The study highlights nature's capacity for self-regulation when key predator species are present. Ongoing monitoring at Elkhorn Slough, a national research reserve, will continue to track these ecological relationships and their broader environmental impacts.