NEMESIS Bioregion Distribution:


Native  Introduced  Cryptogenic  Failed


First Non-native North American Marine/Estuarine Record: 1993
First Non-native West Coast Marine/Estuarine Record: 1993



General Invasion History:

The carnivorous calanoid copepod Tortanus dextrilobatus is native to the coast of China from the Taiwan Strait to the mouth of the Yellow Sea, and to the south coast of South Korea, but is absent from the Yellow Sea itself. This species is characteristic of low-salinity coastal waters (Ohtsuka et al. 1992; Ohtsuka and Reid 1998; Sakaguchi et al. 2011).

North American Invasion History:

Invasion History on the West Coast:

In 1993, this copepod was discovered in western Suisun Bay, California at 3.6 PSU, and by 1999, ranged into San Pablo and the South and Central Bays, over a salinity range of 1.2-28 PSU, reaching densities above 1,000 m-3, which is high for a predatory zooplankter (Orsi and Ohtsuka 1999; Hooff and Bollens 2004). In the lower bay, it was more abundant in San Pablo Bay and South San Francisco Bay than in the central bay (Bollens et al. 2011). It has not been reported from other West Coast estuaries. It has been found in ballast water of ships entering Puget Sound, Washington, but only in those coming from other West Coast ports, presumably San Francisco Bay (Lawrence and Cordell 2010).