People, Shellfish, and Estuaries in Ancient Island and Mainland Southern California

Lay summary authored by Torben Rick (Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC, US). Read the full paper here:

Archaeologists have long been interested in understanding the relationships between past environmental change and human diet and settlement choices. This is particularly true for coastal regions, including estuaries where fresh water and marine systems merge to create dynamic habitats. Glacial to interglacial sea level rise, particularly between about 15,000 and 5000 years ago, created a number of estuaries around the world. These estuaries provided people with rich sources of food, especially shellfish like oysters, clams, and other mollusks.

Rick 1

Figure 1. Location of estuary sites in the Santa Barbara Channel Region dated between about 9000 and 5000 years ago, including the Abalone Rocks Estuary on Santa Rosa Island. Figure by Leslie Reeder-Myers and Torben Rick.

This study explores the importance of estuaries versus rocky shore marine habitats for human diet on the islands and mainland coast of California’s Santa Barbara Channel (Figure 1). Previous research demonstrated that estuaries were important for people living in the Santa Barbara Channel from >11,000 years ago through about 5000 years ago, and in some places through the 19th century. While ancient estuaries appear to have been relatively common along the Santa Barbara mainland coast, they were rare to absent on the adjacent northern Channel Islands, with just one well documented island estuary (Abalone Rocks) (Figure 2). Despite knowledge about this ancient island estuary, we still knew little about the productivity of this estuary and its importance for human subsistence and settlement compared to the more extensive mainland estuaries.

Rick 2

Figure 2. Eastern Santa Rosa Island looking at the Pacific Ocean and the Abalone Rocks Marsh, the remnant of the former Abalone Rocks Estuary (center right of the photo). Photo by T. Rick.

Excavation and subsequent analysis of archaeological shellfish remains from island archaeological sites near Abalone Rocks and similarly aged sites near mainland estuaries provide the first detailed means to compare the importance of mainland versus island estuaries in southern California. This study demonstrates that estuarine shellfish were considerably more abundant at most mainland sites, with shellfish from the Abalone Rocks Paleoestuary largely supplementary to those from rocky shore habitats on the Channel Islands. Estuarine shellfish largely disappear from island sites by about 5000 years ago, effectively ending human use of estuaries for island subsistence. While focused on California’s Santa Barbara Channel, this study illustrates the importance of archaeology for helping understand the relationships between past human diet, land use, and environmental change.

Full paper: Rick, T.C., 2020. Early to Middle Holocene Estuarine Shellfish Collecting on the Islands and Mainland Coast of the Santa Barbara Channel, California, USA. Open Quaternary, 6(1), p.9. DOI:

This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s