First Non-native North American Marine/Estuarine Record: 1973
First Non-native West Coast Marine/Estuarine Record: 1973
First Non-native East/Gulf Coast Marine/Estuarine Record: 1998
Caprella mutica is native to the Northwest Pacific. It was first described from Peter the Great Bay, Russia, by Schurin in 1939, and was subsequently found from the Kurile Islands and Akkeshi Bay in Hokkaido Japan (Ashton 2006) south to the Bohai Sea (Laoning Province) and Jiazhou Bay (Shandong Province) in China (Huang 2001). This caprellid has been introduced to the East (Delaware-Newfoundland) and West coasts (California-Alaska) of North America, Europe (from Spain to Norway and Germany), and New Zealand. Caprellids are capable of long-distance dispersal on floating seaweeds or other objects, but ballast water, ship fouling, and the culture of Pacific Oysters (Crassostrea gigas) are likely vectors for the transport of C. mutica to different regions of the world. Many of the occurrence records are associated with aquaculture facilities and other man-made structures, such as breakwaters, marinas, and oil platforms (Platvoet et al. 1995; Willis et al. 2004; Ashton 2006; Page et al. 2006; Ashton et al. 2007; Cook et al. 2007).
In 1973, Caprella mutica (initially reported as C. acanthogaster) was collected at Field's Landing, in Humboldt Bay, California (Martin 1977, cited by Carlton 1979, Marelli 1981, Boyd et al. 2002). In 1977, it was collected near Oakland in San Francisco Bay (Marelli 1981) and now ranges throughout the South and Central Bay (Cohen et al. 2005). It has been collected at many locations in California, including Elkhorn Slough (in 1978, Marelli 1981), San Diego Bay (in 2001, Fairey et al. 2002, reported as C. acanthogaster), Morro Bay, Channel Islands Harbor, Port Hueneme, Los Angeles-Long Beach Harbors, San Diego Bay (Cohen et al. 2002; Fairey et al. 2002), and oil platforms off Santa Barbara (Page et al. 2006). To the north, it was first collected in Coos Bay, Oregon in 1983 (Carlton 1989; Wonham et al. 2005), Puget Sound, Washington in 1998 and Victoria, British Columbia in 1995 (Cohen et al. 1998; Cohen et al. 2001; Frey et al. 2009). Later it was found to range much farther north, including the Queen Charlotte Islands and Prince Rupert, British Columbia (Frey et al. 2009), and Ketchikan to Kachemak Bay, and Dutch Harbor, in the Aleutian Islands. The timing of this northern invasion is not clear- the earliest Alaskan record is from Sitka in 2001 (Ashton et al. 2008). Pre-existing populations or natural range extensions are conceivable, but extensive collections of caprellids were made in Alaska in the 19th century (US National Museum of Natural History 2012), and in British Columbia in the 20th century (Frey et al. 2009). Potential vectors for C. mutica's transport to the West coast include transplants of Pacific Oysters (Crassostrea gigas), hull fouling, and ballast water.
The earliest collection of Caprella mutica on the East Coast of North America was in 1998 in Brundenel, on Prince Edward Island, Canada, in the Gulf of St. Lawrence (Locke et al. 2007; Turcotte and Sainte Marie 2009). In 2000, in a survey of southern New England harbors, Caprella mutica was collected in many locations from Gloucester, Massachusetts, south to Newport, Rhode Island. A subsequent survey in 2003 extended the range north to Freeport, Maine, and south to Mystic, Connecticut (MIT Sea Grant 2003). In 2013, established populations of C. mutica were found in the Indian River Inlet, Delaware and Ocean City Inlet, Maryland (Macarena Ros, personal communication, 2013). This caprellid was also collected in Passamaquoddy Bay, New Brunswick, Canada (in 2002, Ashton 2006), Placentia Bay on the south shore of Newfoundland (in 2010, Fisheries and Oceans Canada 2011), and at several more locations in the Gulf of St. Lawrence, including Chaleur Bay (in 2003) and the Magdalen Islands, Quebec (in 2005, Turcotte and Sainte Marie 2009).
Caprella mutica was first reported in European waters from a surge barrier in Zeeland, and Burghsluis, Netherlands, on the Eastern Scheldt estuary, where it was named as a new species C. macho (Platvoet 1995). In 1999, it was found near a salmon farm in Oban, on the west coast of Scotland (Willis et al. 2004), the Shetland Islands and in Austevoll, Norway (Skifterik 2001; Ashton 2006; Cook et al. 2007). This caprellid is now known from much of the coast of Northwestern Europe, from Le Havre, France (on the English Channel) to Helgoland, Germany (on the North Sea), including the Channel Coast of England, the east and west coasts of Scotland, and the west and east coasts of Ireland (Tierney et al. 2004; Buschbaum and Gutow 2005; Ashton 2006; Arenas et al. 2006; Ashton et al. 2007; Cook et al. 2007; Schückel et al. 2010).
In the Southwest Pacific, Caprella mutica is established near Timaru and Lyttleton on the South Island of New Zealand (Willis et al. 2009).