Protecting California's Deep

The deep ocean off California's coastline is home to an exceptional array of seamounts, ridges and banks, ranging from 45 to 185 miles offshore. These ancient islands and underwater mountains host fragile living habitats, delicately intertwined food webs and spectacular marine biodiversity. 

California’s seamounts harbor 500-year-old corals and sponges thriving in the cold, dark depths. The food produced by these nutrient-rich waters offer much-needed fueling stations for migratory predators, such as sharks, tunas, billfishes, sea turtles, seabirds and whales. Marine scientists and conservation organizations have noted the significance of these special ocean places, which house some of the only hydrothermal vent systems in U.S. waters and support unique sea creatures. These deep areas are a vital frontier for scientific discovery, as expeditions yield new and rare ocean species with unique properties that make them interesting to biomedical researchers.

The deep sea is likely to experience unprecedented change in coming years. Warming waters, acidification and deoxygenation are occurring in our global ocean, and irreversible damage can occur before we understand the true value of these places. Seamounts are especially vulnerable to human activities like fishing, mining and oil exploration that could destroy their unique habitats and the fragile food webs that rely upon them.

While state and federal catch data indicate that fishing on these sites is minimal, the Pacific Fishery Management Council has recognized the importance of these places by prohibiting bottom trawling at many of these unique geological features. These regulations still allow potentially damaging bottom-tending gear, such as traps and longlines, and provide no protection from other activities.

Marine protected areas (MPAs) are a proven tool to safeguard ocean health for the future. Left intact, these deep-water habitats can serve as refuges for sea creatures in the face of human impacts. Yet less than 1% of the deep-sea habitats off California are permanently protected. Marine Conservation Institute is a proud member of the California Seamounts Coalition working to secure protection for California’s deep-sea marine biodiversity and seamounts, ridges and banks. Learn more at: