NEMESIS Bioregion Distribution:

This species is a freshwater species with occurrences in tidal fresh or brackish waters and does not have a marine bioregion map associated with it. Please click on the Distribution Details tab for a North American distribution map. Additional information on this species and its distribution can be found in the USGS Nonindigenous Aquatic Species Database

First Non-native North American Marine/Estuarine Record: 1995
First Non-native West Coast Marine/Estuarine Record: 1995

General Invasion History:

Palaemon modestus (Siberian Prawn) is native to eastern Asia, from the Amur River Basin, Russia, through southern China. It is usually restricted to fresh and oligohaline waters (0-4 PSU) in Asia, and occurs in large rivers, lakes, and reservoirs (Kwon and Uno 1968; Holthuis 1980; Emmett et al. 2002; Guo et al. 2005). This species has been introduced to the Western Coast of North America and is found in parts of Washington, Oregon and California.

North American Invasion History:

Invasion History on the West Coast:

Palaemon modestus was first found in North America in the tidal portion of the lower Columbia River near Goble, Oregon in September, 1995 (Emmett et al. 2002). Since 1995, this shrimp has become abundant in the Columbia River, from Bonneville Dam, at the head of tide, past Portland to Miller Sands, 38 km from the river mouth (Emmett et al. 2002). Most captures of P. modestus have been in fresh water. In 2005, P. modestus was collected in the Snake River near Lower Granite Lake Dam, in Washington State (Haskell et al. 2006;  USGS Nonindigenous Aquatic Species Program 2009). In 1997, it was collected in the Umpqua River drainage, on the central coast of Oregon, and is established there (USGS Nonindigenous Aquatic Species Program 2009).

In 2001, P. modestus was first collected in the San Francisco estuary at Stockton, California, Sacramento River (USGS Nonindigenous Aquatic Species Program 2007). Its population grew rapidly. By 2005, it ranged from Wards Landing (Colusa County) on the Sacramento River, south to Mud Slough (Merced County) on the San Joaquin River, and downstream to Suisun, Grizzly, and Honker bays to Carquinez Strait, and infrequently in San Pablo Bay (Hieb 2007). In San Fancisco Bay, P. modestus has colonized brackish waters, reaching mesohaline salinities. In fresh-oligohaline parts of the Delta, it has become the dominant shrimp, largely replacing Palaemon macrodactylus, the Oriental Shrimp (Hieb 2007).