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Regional Overview & Fact Sheet
The Southern Californian Pacific is a region of mixing—of both waters and faunas—from north and south, characterized by relatively high species diversity. The confluence of the rich, cold California Current and warmer waters from the south make this region a complex transition zone between warm and cold temperate biota. The region also includes the northernmost extension of mangrove and the southernmost extension of kelp in the eastern Pacific. Abundant stands of giant kelp found around the offshore islands and along the mainland provide a home for a wide variety of invertebrates, fishes, seabirds and marine mammals. The region is home to important breeding and calving areas for the gray whale—a species with one of the longest migratory routes of all mammals. The Southern Californian Pacific, which stretches along the Pacific Coast from the southern tip of Mexico’s Baja California peninsula at Cabo San Lucas, north to Point Conception, California in the United States, also includes highly urbanized coastal areas of Southern California (USA) and Tijuana and Ensenada (Mexico).
The Region includes seven B2B Marine Priority Conservatiton Areas (PCAs): PCA 17-Upper Bight of the California/Channel Islands/San Nicolas Island (shared with the Montereyan Pacific Transition Ecoregion); PCA 18-Lower Bight of the Californias/Islas Coronados; PCA 19-Bahía San Quintin/Bahía El Rosario; PCA 20-Isla Guadalupe; PCA 21-Vizcaíno/Isla Cedros; PCA 22-Laguna San Ignacio; and PCA 23-Bahia Magdalena (Morgan et al. 2005).
Fact Sheet
A region of mixing—of both waters and faunas—from north and south, characterized by relatively high species diversity. The northern boundary is a major biogeographic transition zone for fish and invertebrates, the northern range terminus of many low-latitude species, and the southern range terminus of many high-latitude species.
15–18°C (winter), 19–22°C (summer)
California Current and Davidson Current
Geomorphologically complex region.
shelf (roughly 0–200 m): 8%;
slope (roughly 200–2,500/3,000 m): 20%
abyssal plain (roughly 3,000+ m): 72%
Sand and rock.
Coastal lagoons (with mangroves in the south), seagrass beds, rocky shore, tidal pools, sand shores, kelp beds, and continental platform bottom communities.
The California Current is considered a moderately high productivity ecosystem (150-300 gC/m2-yr). The region’s undergo seasonal upwellings of cold nutrient rich water that generate localized areas of high primary productivity that support fisheries for sardines, anchovy, and other pelagic fish species.
White, green and pink abalones.
Minke, sei, Bryde’s, blue, gray and fin whales; Guadalupe fur seal; southern sea otter; California least tern, short-tailed albatross, Xantus' murrelet, pink-footed shearwater; cowcod and boccacio rockfish; white, green, black and pink abalones. Species such as silky shark, scalloped hammerhead, and smooth hammerhead that are presenting signs of overeploitation from artisanal shark fisheries targeted at immature individuals. Other species of concern include whale shark, basking shark, great white shark, Garibaldi damselfish, sawfishes and mantas (giant manta, spinetail mobula, smoothtail mobula, pygmy devil ray, and sicklefin devil ray).
Breeding and calving lagoons of the gray whale; Ensenada and San Lucas oceanographic fronts are highly productive areas.
Fisheries, coastal tourism and urban development. Offshore fisheries may be affecting species with low fertility rates such as pelagic thresher and bigeye thresher.
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Physical and Oceanographic Setting
The Southern Californian Pacific is characterized by a very narrow continental shelf, which widens slightly in the south to between 110 and 140 km at Bahía Sebastián Vizcaíno, and just north of Bahía Magdalena. At the shelf break, the seafloor drops rapidly to 1,000 and 3,000 m depths. Seaward of the shelf, but landward of the Southern Californian Plains and Seamounts are the Baja California Borderlands—a mountainous region, found at depths between 800 and 1000 m, that includes islands, banks and deep basins. The Southern Californian Pacific also includes islands emerging from its abyssal plain, such as Isla Guadalupe, Rocas Alijos and the Channel Islands (which include San Clemente, Santa Catalina, San Nicolas, Santa Cruz, Santa Rosa, and San Miguel). The bottom type found in the coastal regions varies from sandy to rocky.
The climate is arid to semi-arid, and has limited freshwater input to the coast. In the northern part, to approximately 350 km south of the US-Mexico border, a Mediterranean climate is found.
The region is affected by various currents and upwellings at different times of year. The region is dominated oceanographically by the north-to-south flowing California Current that carries relatively cold nutrient-rich waters. At Point Conception, the California Current moves farther offshore, allowing the near-shore current to be influenced by the warmer Southern California Countercurrent (which has a discontinuous northward flow beginning seasonally in August-October and strengthening in winter). Southern California Countercurrent and extensions of the Costa Rica Coastal Current influence the coastal region, mainly during winter. Intense coastal upwelling events occur during spring and summer. Seasonal upwelling cells southward of prominent capes and headlands occur near Point Conception, Cape Colonett, Punta Baja, Cape San Quintín, Punta Eugenia, Punta Abreojos, and Cape Falso. Counterclockwise gyre systems occur in the Southern California Bight and Bahía Sebastián Vizcaíno.
The Baja California Frontal System (BCFS) is a dynamic region covering a zone 500 by 250 km, centered about 150 km off the Pacific coast of Baja California Sur. It is characterized by a persistent high concentration of frontal features, generated by the confluence of the cool southbound California Current and warmer northbound Davidson Current as it intersects the Baja California Peninsula. The BCFS appears more active under La Niña conditions (Etnoyer et al. 2004).
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Biological Setting
The Southern Californian Pacific is a region of mixing—of both waters and faunas—from north and south, characterized by relatively high species diversity. The southern range terminus of many high-latitude marine fishes, invertebrates, and algae as well as the northern range terminus of many equatorial species occurs around Point Conception and the northern Channel Islands (Airamé et al. 2003). Productivity in the Southern Californian Pacific is moderately high due to the coastal upwelling systems, which bring nutrients to the surface near shore. With intensive upwelling, also comes greater recruitment success for commercially important fish stocks. Fishes migrate large distances to the southern California Bight between upwellings to spawn. El Niño Southern Oscillation (ENSO) conditions which bring warm equatorial waters further north, decrease productivity and recruitment success of many species, and hinders community dynamics of the region. These interannual variations are superimposed on Pacific Decadal Oscillations consisting of a sequence of warm and cold regimes. ENSO events have a great impact on this region during a warm regime, reducing the abundance, diversity and stability of the near-shore giant kelp community.
The Southern Californian Pacific includes the northernmost extension of mangrove habitats in the eastern Pacific (close to Bahia Sebastian Vizcaino), and the southernmost extension of giant kelp beds (near Bahia Magdalena). Giant kelp beds at depths of 6 to 30 m are among the most productive marine habitats, providing food and shelter for numerous invertebrates like the Spanish shawl and its preferred prey, the stickyhydroid, fishes, seabirds and marine mammals.
The region also supports large seabird and marine mammal populations. Pink-footed shearwater, short-tailed albatross and Xantus’ murrelet—all highly migratory seabirds at risk of extinction—use the productive waters in this region for feeding. The breeding colonies of Xantus’ murrelet are found between Islas San Benito and Guadalupe Island and the northern California Channel Islands. Major California sea lion rookeries occur at the Channel Islands and Bahia Sebastian Vizcaino, and important northern elephant seal rookeries occur at San Miguel Island, Santa Barbara Island, Islas San Benito and Guadalupe Island. The Guadalupe fur seal—a transboundary species at risk, with a very limited range—is found in these waters between Isla Guadalupe off the Baja California peninsula and San Nicolas Island off southern California. The species’ breeding and pupping occurs on Isla Guadalupe as well as Isla San Benito del Este, Mexico. Likewise, Laguna Guerrero Negro, Laguna Ojo de Liebre (Scammon’s Lagoon), Laguna San Ignacio, Santo Domingo Channel, and Bahia Magdalena are the most important breeding and calving areas for the gray whale—a species with one of the longest migratory routes of all mammals (22,000 km yearly from the Bering Sea to Baja California). Over 27 species of whales and dolphins also visit the Channel Islands (USA).
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Human Activities and Impacts
The Southern Californian Pacific Region includes highly urbanized coastal areas of southern California and Tijuana, as well as sparsely populated coasts of Baja California and Baja California Sur. Los Angeles, Orange and San Diego counties, bordering the Southern California Bight, 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 into US waters have been decreased by 50 to 99 percent since the 1970s, resulting in improvements in benthic/demersal and kelp communities, and reductions in contaminants in fish and marine mammals.
The region is rich in a variety of fishery resources. Anchovies and sardines are key links in the local trophic system. Other commercial fishes include Pacific chub mackerel, Pacific bonito, jack mackerel, Pacific hake and over 60 species of rockfishes. In the US Pacific coast (ecoregions 19, 20 and 21), six out of 48 federally managed stocks are overfished, with 13 of unknown status (NMFS 2007).
Coastal regions vary significantly in the degree of human alteration—from relatively uninhabited to highly modified—and include major centers of marine transportation, recreation and offshore oil production. For the once relatively pristine but rapidly developing area of the northern Baja California peninsula coast, and its neighboring southern California coast with its thriving economy, issues of concern stem from oil and gas development, busy shipping lanes, non-point sources of pollution, riverbed exploitation for sand, thermoelectrical plants, vacation homes and tourism infrastructure, as well as commercial and recreational fishing.
Level II and Level III Descriptions
Level II captures the break between neritic (near shore) and oceanic areas and is determined by large-scale physiography (continental shelf, slope, and abyssal plain, as well as areas of oceanic islands and major trenches, ridges and straits). This level reflects the importance of depth as a major determinant of benthic marine communities as well as the importance of major physiographic features in determining current flows and upwelling. Like Level I, it extends from the coasts to the EEZ.
Level III captures differences within the neritic realm and is based on more locally significant variables (local characteristics of the water mass, regional landforms, as well as biological community type). Level III is limited to the continental shelf, since only this area has sufficient information for finer-scale delineation.
Level II and Level III Ecoregions
Other Marine Ecoregions
Marine ecoregions are areas of general similarity in terms of physiographic, oceanographic and biological characteristics, which fall within the Exclusive Economic Zones of the North American countries. There are 24 marine ecoregions in North America.
