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Summary and Findings

Monterey Bay National Marine Sanctuary is the largest national marine sanctuary and one of the largest marine protected areas in the United States. Within the boundaries of the sanctuary is a rich array of habitats, from rugged rocky shores and lush kelp forests to one of the largest underwater canyons in North America. These habitats abound with life, from microscopic plants to enormous blue whales. The sanctuary is home to a diversity of species including marine mammals, seabirds and shorebirds, sea turtles, fishes, invertebrates, and marine algae.

Activities that put pressure on sanctuary resources are diverse. Some of the most prominent pressures include vessel traffic, commercial and recreational fishing, agricultural and urban runoff, harmful algal blooms, coastal development, marine debris, the introduction of non-indigenous species, and disturbances to wildlife.

Because of the considerable differences within the sanctuary between the offshore, nearshore, and estuarine environments, each question found in the State of the Sanctuary Resources section of this report was answered separately for each of these environments. The offshore environment is defined as extending from the 30-meter isobath out to the offshore boundary of the sanctuary and includes the seafloor and water column. The nearshore environment is defined as extending from the shoreline boundary of the sanctuary (mean high water) to the 30-meter isobath and includes the seafloor and water column. Though many small estuaries occur along the central California coastline, they are not within the boundaries of the sanctuary. Elkhorn Slough is the only large estuary located inside the boundaries of the Monterey Bay sanctuary, and is thus the focus of the estuarine environment section in this report.

Water quality parameters in the offshore environment of the sanctuary suggest degraded conditions. The main contributors to degraded water quality conditions are land-based activities, such as those linked to urban development and agriculture that input contaminants and nutrients into offshore sanctuary waters, and vessel traffic that can result in the discharge of ballast water, bilge oil, and marine debris. Habitat modification has occurred in the offshore environment of the sanctuary; the most significant physical alteration of sanctuary habitats has likely resulted from fishing with bottom-contact gear, such as otter trawls. Among the various environmental impacts resulting from use of this type of gear are removal of structure-forming organisms and the smoothing of bedforms. A variety of recent management measures directed towards trawling may allow for an improvement in the condition of offshore habitats due to some recovery of seafloor habitats in the areas that were previously trawled. Living resource conditions within the offshore environment of the sanctuary are considered to be diminished as the relative abundance of many species, such as marine mammals, seabirds, and predatory fishes, have been altered substantially by both natural and anthropogenic pressures over the past several hundred years. In addition, the health of several key species has been compromised by exposure to neurotoxins produced by harmful algal blooms, entanglement in active and lost fishing gear, ingestion of marine debris, and accumulation of persistent contaminants. Recent management actions to reduce marine debris and to recover overfished stocks and impacted habitats were implemented to improve the state of living resources, and in some cases they have begun to do so. There is great uncertainty regarding the integrity of submerged maritime archaeological resources in the offshore environment in the sanctuary. The sanctuary’s inventory contains information on known vessel losses, with little to no verified location information, and few visited sites. In addition, NOAA has conducted only one offshore archaeological site location inventory in the sanctuary.

Water quality parameters in the nearshore environment of the sanctuary suggest slightly more degraded conditions in comparison to the offshore environment. Specific stressors to water quality include the input of contaminants, nutrients, sediments, and pathogens from land-based activities that are linked to urban development and agriculture. Efforts to reduce pollution in the sanctuary may be offset by intensification of human activities in coastal watersheds that introduce pollutants to the nearshore environment. In the nearshore environment of the sanctuary there has been localized modification or loss of coastal habitat, primarily through armoring of coastal bluffs and beaches, erosion of sandy shoreline, and landslide disposal on rocky reef. On-going monitoring studies indicate that large, structural algae, seagrasses, and sessile habitat-forming invertebrates (e.g., sponges, anemones, tube worms) appear to be healthy and no major perturbations have been observed. The relative abundance of native species, including abalone, mussels, and sea otters, in the intertidal and nearshore subtidal zones has been altered throughout the sanctuary by a variety of factors including human activities, such as trampling and harvesting for human consumption. The recent implementation of multiple marine reserves and conservation areas in nearshore waters may facilitate recovery of reduced populations. Little is known about the submerged maritime archaeological resources in the nearshore environment of the sanctuary. To date, only one nearshore archaeological site location inventory has been conducted in the nearshore environment of Monterey Bay sanctuary.

Over the past 150 years human actions have altered the tidal, freshwater, and sediment processes in the Elkhorn Slough and its watersheds. Such impacts have substantially changed the water quality conditions and have increased the levels of pollution in Elkhorn Slough. In addition, these alterations have resulted in substantial erosion and habitat conversion. Most notably, there has been a severe reduction in abundance of the two native species that form biogenic habitat in the main channel of Elkhorn Slough, eelgrass (Zostera marina) and native oyster (Ostrea lurida), as compared to historic levels. In addition, there is strong evidence that these changes to estuarine habitats have substantially altered local biodiversity in the past 150 years – some species, including burrowing sand anemones and the Atlantic soft-shell clam, that were noted as abundant in portions of the Elkhorn Slough in the 1920 and 1930s are now rarely encountered. Also, there is a very high percentage of non-native species in Elkhorn Slough, including the Japanese mud snail and the bright orange sponge. Management agencies have worked with local stakeholders to create regulatory, monitoring, education, and training programs and to implement better agricultural and urban management practices aimed at reducing or eliminating impacts to Elkhorn Slough. Little is known about the integrity of maritime archeological resources in Elkhorn Slough.

A new management plan for Monterey Bay National Marine Sanctuary was released in November 2008, and it contains a number of management actions that will address current issues and concerns. The plan stresses an ecosystem-based approach to management, which requires consideration of ecological interrelationships not only within the sanctuary, but within the larger context of the California Current ecosystem. It also makes essential an increased level of cooperation with other management agencies in the region. The management plan includes twenty-nine action plans that will guide the sanctuary for the next five to ten years.

Monterey Bay National Marine Sanctuary
  • 6,094 square statue miles (4,602 square nautical miles)
  • Congressionally designated in 1992 as a National Marine Sanctuary for the purpose of resource protection, research, education, and public use.
  • Includes bays, estuaries, coastal and oceanic waters
  • High diversity of flora and fauna including 33 species of marine mammals, 94 species of seabird, 345 species of fishes, and numerous species of invertebrates and plants
  • Contains the Monterey Canyon, a submarine canyon that rivals the Grand Canyon in size
  • Contains an estimated 225 documented shipwrecks or lost aircraft and 718 historic sites

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