Morro Bay

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Morro Bay

The part of Morro Bay included here consists of the central and southern portions not within the State Park. This section of the bay supports three habitats: coastal salt marsh, tidal mud flats and deep-water channels.

The salt marsh is relatively undisturbed and extensive; it is dominated by pickleweed, Salicornia virginica, though in some of the higher ground salt-grass, Distichlis spicata, Jaumea carnosa, and alkali heath, Frankenia grandifolia, are found. It is in this community that the rare Cordylanthus maritimus ssp. palustris occurs.

Eel grass, Zostera marina, and various algae are found in the open-water marine zone, with some algae in the lower tidal flats. Some 32 species of algae have been identified in the vicinity. The upper edges of the tidal mud flats are generally devoid of vegetation but are rich in invertebrates.

Morro Bay is one of the more important migratory coastal stops on the Pacific Flyway. Upwards of 25,000 individual waterfowl have been counted on a peak day, and 89 species of water-oriented birds have been observed here. Among the more unusual are the whistling swan, Olor columbianus, snow goose, Chen hyperborea, and the elegant tern, Thalasseus elegans. Black brant, Branta nigricans, are attracted by the Zostera and, at times, are very abundant. The rare black rail, Laterallus jamaicensis coturniculus, has been observed here; however, the endangered California clapper rail, Rallus longirostris obsoletus, which formerly bred here, has not been observed recently.

A total of 66 species of fish has been collected in the bay and the first mile of Los Osos Creek (see Los Osos Estuary). Of the salt-water species, three, the northern anchovy, Engraulis mordax, the shiner perch, Cymatogaster aggregata, and black perch, Embiotoca jacksoni, comprised half of the total individuals collected. At least 15 species appear to breed in the bay.

Four mammals have been sighted, the Steller sea lion, Eumetopias jubata, the California sea lion, Zalophus californianus, the harbor seal, Phoca vitulina, which occasionally pups here, and the sea otter, Enhydra lutris, which here is probably at the southern limit of its present distribution.

Some 120 species of invertebrates have been recorded here, including 19 species of clams of which the Washington, Saxidomus nuttalli, the gaper, Tresus nuttalli, and the geoduck, Panope generosa, are the most common, 34 species of polychaete worms and 20 species of amphipod crustaceans.

Formerly the bay was a true bay at the western end of the Los Osos Valley; however, the deposition of the sand spit has created a lagoon.

Integrity: A portion of the bay is used for recreation, hunting and fishing. There is a commercial oyster farm. Some tidal flats are private.

Use: Research, educational, observational, present.

Ref: Gerdes, G. L., et al. 1974. Natural Resources of Morro Bay, Their Status and Future. Calif. Dept. of Fish & Game Coast. Wet. Ser. #8, 103 pp.

September 1976