17. Upper Bight of the Californias/Channel Islands/San Nicolas Island

Site Overview

This PCA stretches from just north of Point Conception, California (part of the Montereyan Pacific Transition Ecoregion), south into the Southern California Bight, including the Channel Islands (part of the Southern Californian Pacific Ecoregion). This PCA straddles the largest biogeographic transition zone in the California Current. Many temperate species have their southernmost occurrences in this area, while many subtropical species have their northernmost occurrences here.

This PCA contains a diversity of habitats, including kelp beds, sandy and rocky shores, offshore banks, coral studded pinnacles and steep submarine cliffs. The Channel Islands are home to diverse mammals and seabirds. More than 27 species of whales and dolphins also visit the Channel Islands (United States). More than 25 species of sharks inhabit the surrounding waters of the Channel Islands (Ebert 2003). The blue shark (Prionace glauca) is a common resident, as is the white shark. Kelp forests provide habitats for a great diversity of fishes, including Garibaldi (Hypsypops rubicundus), sheepshead (Semicossyphus pulcher), senorita (Oxyjulius californica), blacksmith (Chromis punctipinnis), torpedo rays (Torpedo californica) and moray eels (Gymnothorax mordax). Numerous species, including giant seabass (Stereolepis gigas), white seabass (Atractoscion noblis), yellowtail (Seriola lalandi), California halibut (Paralichthys californianus) and spiny lobster (Panulirus interruptus), have declined under the pressure of commercial and recreational fishing (Dayton et al. 1998). More than 60 species of rockfish (Sebastes spp.) inhabit this region (Love et al. 2002), including cowcod (Sebastes levis) and bocaccio (S. paucispinis), both currently overfished. Several abalone species have undergone severe declines (Rogers-Bennett et al. 2002), and the white abalone (Haliotis sorensi), is listed under the US Endangered Species Act.

The Northern Channel Islands and Santa Barbara Island are key breeding habitat for Xantus’ murrelet and are the only nesting site for black storm petrels (Oceanodroma melania) in the United States. Anacapa Island is the only permanent nesting site for brown pelicans (Pelecanus occidentalis) in California. Northern fulmars (Fulmarus glacialis) breed in the Bering Sea region, but the Channel Islands are the southern extent of their non-breeding range.

The Channel Islands are also key habitats: specifically, San Nicolas Island for sea otter and the Guadalupe fur seal (Arctocephalus townsendi), and San Clemente Island for the Guadalupe fur seal. This area is also a major breeding and haulout region for California sea lions and northern fur seals (Callorhinus ursinus), following feeding farther north off British Columbia. Major California sea lion rookeries occur at San Miguel and Santa Barbara Islands. Other abundant pinnipeds include the northern elephant seal and Pacific harbor seal.

The common dolphin (Delphinus delphis) is the most abundant cetacean species off the southern California coast, and may be seen traveling in pods up to 1,000 individuals. The area is a hotspot of marine mammal diversity and abundance (Ford and Bonnell 1996). The San Pedro and Santa Barbara Channels are known as key feeding habitats for the humpback whales and serve as a migratory corridor. In addition, the Channel Islands are key feeding habitats for blue whale (Fiedler et al. 1998). Gray whales migrate through the region.

The land bordering this marine ecoregion is heavily populated. Los Angeles, Orange and San Diego counties have the first-, fifth- and sixth-largest populations in the United States, respectively, collectively totaling more than 15 million people. Despite rapid increases in population, wastewater discharges of most pollutants have been decreased by 50 to 99 percent since the 1970s in Los Angeles, Orange and San Diego counties, resulting in improvements in benthic and kelp communities and reductions in contaminants in fish and marine mammals (Schiff et al. 2000).