The Monterey Bay National Marine Sanctuary

Monterey Bay holds the closest-to-shore deep ocean environment in the continental U.S. and one of North America’s largest submarine canyons, but it was the threat of offshore oil development that in 1992 led to the creation of the Monterey Bay National Marine Sanctuary, the nation’s largest. This huge preserve covers 5312 square miles including 360 miles of coastline from the Marin Headlands to Cambria in San Luis Obispo County. It protects the coast from the high tideline to about 50 miles offshore. In addition to sheltering the Monterey Submarine Canyon, the sanctuary protects the entire habitat of the endangered southern sea otter, one of the most important marine estuaries in California, Elkhorn Slough, and the most diverse algal community in the nation.

One of the four sanctuaries on the California coast administered by the National Oceanic and Atmospheric Administration, the Monterey Bay National Marine Sanctuary protects the marine environment and encourages and coordinates research and education activities. The sanctuary permits traditional uses such as fishing and recreation, but bans oil and gas development and seabed mining. It requires high treatment levels for sewage before discharge, and generally discourages activities that damage the marine environment. The sanctuary ranges from the shallow land wrapped waters of Elkhorn Slough to the depths of Monterey Canyon.

Monterey Canyon rivals Arizona’s Grand Canyon in size, but it’s submerged and difficult to see. The canyon’s shallow end begins just offshore from Elkhorn Slough and plunges to almost two miles deep at its western end. Inhabitants include giant squid, the great white shark, and blue, gray, sperm, finback and humpback whales. In the spring, water begins upwelling from deep in the canyon, bringing nutrients to the surface which feed the phytoplankton to begin the food chain, the basis of the rich marine environment.

Elkhorn Slough is an extension of Monterey Canyon. It was an ancient river valley flooded by the rising ocean that has since filled with sediment. Today this important marsh and tidal flat reaches seven miles inland, encompassing 2500 acres. Human activity has heavily impacted the area, including the dredging of Moss Landing Harbor in 1947 which created an opening to the ocean where none existed before. Still, the marsh remains a vital habitat for marine invertebrates, fish, shorebirds and five endangered species: the brown pelican, least tern, Santa Cruz long-toed salamander, southern sea otter and peregrine falcon.

The Monterey area has long attracted scientists because of the diversity of its habitats and variety of living organisms. Five marine research stations study wetlands, sandy beaches and sea floor, rocky shorelines, extensive kelp forests, and Monterey Canyon. These habitats are home to 27 species of marine mammals, 94 species of seabirds, 345 species of fishes, and a diverse and rich population of marine invertebrates.