NEMESIS Bioregion Distribution:

Native  Introduced  Cryptogenic  Failed

First Non-native North American Marine/Estuarine Record: 1985
First Non-native West Coast Marine/Estuarine Record: 1985

General Invasion History:

Ciona savignyi appears to be native to Japan and possibly northern Asia. In Japan, it can be found from Mutsu Bay (north end of Honshu) to the Seto Inland Sea (south end of Honshu), both on the Pacific and Sea of Japan coasts (Hoshino and Nishikawa 1980; Nishikawa 1991). In 2004, it was first collected as an introduced species in the most northern reaches of the Sea of Japan, in Peter the Great Bay, Russia (Zvyagintsev et al. 2007). In the northeast Pacific, there are two puzzling records from southeastern Alaska (Inside Passage: Loring, in Behm Canal) and northern British Columbia (Stuart Island, in Queen Charlotte Strait) (AK in 1903, USNM 5633, U.S. National Museum of Natural History 2003; BC in 1937, Lambert 2003). These could represent a cryptic species, a very early introduction, or a relict population. There are also disjunct records from Argentina (Hoshino and Nishikawa 1985) and Spain (Perez et al. 1957) which for the purposes of this database, we consider unverified. However, C. savignyi has recently invaded shallow coastal waters of central and southern California and Puget Sound (Cohen and Carlton 1995; Lambert and Lambert 1998; Lambert 2003; Cohen et al. 2005; Blum et al. 2007).

North American Invasion History:

Invasion History on the West Coast:

The first record of Ciona savignyi in continental US waters was in 1985 in Long Beach Harbor, southern CA (Lambert and Lambert 1998). In 1993, it was collected in central California, San Francisco Bay (Cohen and Carlton 1995). By 1994 the southern California population ranged from San Diego Bay to Santa Barbara Harbor, CA (Lambert and Lambert 1998; Lambert and Lambert 2003). The central California population soon included specimens collected in 1998 Elkhorn Slough surveys (Wasson et al. 2001) and in 2003 Monterey and Moss Landing Harbors samples (deRivera et al. 2005). As of 2005, C. savignyi has been collected in the central and southern sections of San Francisco Bay, but not the more northern San Pablo Bay (Cohen et al. 2005; Ruiz et al. unpublished data). North of San Francisco Bay, C. savignyi has been found in samples collected from Tomales Bay (in 2001, Fairey et al. 2002), Bodega Harbor (deRivera et al. 2005), and Humboldt Bay, CA (in 2001, Fairey et al. 2002; Ruiz et al. unpublished data).

In Washington, C. savignyi has spread throughout Puget Sound. It was first discovered in 1998 in the Des Moines Marina near Seattle and by 1999 it had spread north to the Brownsville and Edmonds Marinas. In 2001, it was found near the Tacoma Yacht Club in Tacoma, WA (Lambert 2003). Subsequently, scuba divers discovered extensive populations in several other parts of Puget Sound, including Hood Canal in the western portion of Puget sound (in 2005, USGS Nonindigenous Aquatic Species Program 2003-2012) and in more northern reaches of the San Juan Islands (USGS Nonindigenous Aquatic Species Program 2003-2012).