Aquatic Invasions (2006) Volume 1, Issue 3: 137-142 DOI 10.3391/ai.2006.1.3.7 © 2006 The Author(s) Journal compilation © 2006 REABIC (http://www.reabic.net) This is an Open Access article Research article First records of Eriocheir sinensis H. Milne Edwards, 1853 (Crustacea: Brachyura: Varunidae) for Chesapeake Bay and the mid-Atlantic coast of North America Gregory M. Ruiz1*, Lynn Fegley2, Paul Fofonoff1, Yongxu Cheng3 and Rafael Lemaitre4 1Smithsonian Environmental Research Center, Edgewater, Maryland 21037 USA Email: [email protected] ; [email protected] 2Maryland Department of Natural Resources, Annapolis, Maryland 21401 USA Email: [email protected] 3Shanghai Fisheries University, Shanghai 200090, China Email: [email protected] 4Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC 20560 USA Email: [email protected] *Corresponding author Received 6 September 2006; accepted in revised form 11 September 2006 Abstract We report here the first Chinese mitten crabs, Eriocheir sinensis H. Milne Edwards, 1853, found in the Chesapeake Bay, USA. Two male specimens were caught, retained, and identified from the mouth of the Patapsco River, near Baltimore, Maryland. The first crab to be reported was captured on 9 June 2006. Surprisingly, the second reported crab was captured at least one year earlier, probably in May 2005. Another two specimens of E. sinensis were reported up to 90km south of this location in April- June 2006, but the identity of these latter crabs could not be confirmed, because the specimens were not kept. Environmental conditions in Chesapeake Bay appear suitable for colonization by E. sinensis, and it is presently not known whether mitten crabs are reproducing or established in the region. Key words: Eriocheir sinensis, Chesapeake Bay, North America, nonindigenous species not clear whether established populations are Introduction present in any of these areas (Petit 1960, Petit and Mizoule 1973, Clark et al. 2006, Robbins et al. The Chinese mitten crab, Eriocheir sinensis H. 2006, Minchin in press). Milne Edwards, 1853, was introduced to northern In North America, E. sinensis is only known to Europe, where it is now widespread and have established a single population that is very considered established from Finland to southern restricted geographically on the west coast, France, including England (Herborg et al. 2003, occurring in the San Francisco Bay Delta of Panov 2006, Robbins et al. 2006). The crab also central California (Cohen and Carlton 1997, U.S. has been recorded in Ireland, the Mediterranean National Management Plan 2003, Rudnick et al. Sea, Black Sea, Sea of Azov, Caspian Sea 2003, 2005). One other confirmed occurrence of a (northern Iran), and southern Iraq, although it is mitten crab along this coast was a single specimen 137 G.M. Ruiz et al. reported from the Columbia River, at the border Following announcements and media coverage between Oregon and Washington, and was of this initial crab (e.g., Maryland Department of described as E. japonicus (De Haan, 1835), Natural Resources 2006, Williamson and originating from a different geographic source Fahrenthold 2006), a second specimen was than the California crabs (Jensen and Armstrong reported from the same approximate location, at 2004; see also McLaughlin et al. 2005). the mouth of the Patapsco River, Maryland, and Mitten crabs have also been reported in eastern was also captured in a baited crab trap (J. Foltz, North America, occurring in two different personal communication). This second crab was regions, but are not thought to be established. apparently captured at least one year prior to the Since 1965, at least eleven different specimens first reported crab, probably in May 2005, have been reported as E. sinensis from the although there is some uncertainty about the exact Laurentian Great Lakes and St. Lawrence River date. The crab was maintained live for several (Annex), along the border between Canada and months in captivity and then frozen (S. Takos, the United States. This includes eight specimens personal communication), being delivered to us in from Lake Superior to Lake Erie (including the August 2006. The second specimen is also a male, Detroit River), and three specimens collected near 62mm carapace width. Quebec, Canada. In addition to these northern To date, we have received two additional records, a single mitten crab was reported in 1987 reports of mitten crabs in the Chesapeake Bay that from the Mississippi River delta, Louisiana, in the appear credible, although the specimens were not southeastern United States and along the Gulf of retained and identification cannot be confirmed. A Mexico. In total, at least three of the mitten crabs third crab was reported from the mouth of the collected from eastern North America have been Patuxent River, Maryland in Chesapeake Bay preserved and deposited in museums (Annex). (38º18'N, 76º25'W). This crab was captured in a Here, we report the first records of the Chinese crab trap in late April 2006 (M.Wolfe, personal mitten crab for the Chesapeake Bay, Maryland, communication) and fits the general description of USA. To our knowledge, this is the first a Chinese mitten crab. This specimen was confirmed occurrence of E. sinensis for the U.S. reported to be approximately 60mm in carapace Atlantic coast between the Gulf of Mexico width. A fourth specimen was reported from a (Louisiana) and the U.S.-Canadian border. The crab trap in the vicinity of Chesapeake Beach, Chesapeake specimens were collected at least Maryland (38º41'10"N, 76º32'05"W; E. O’Brien, 1,000km by contiguous waterways from prior personal communication). The fourth crab was records in the Gulf of Mexico, Great Lakes and reported to be of similar size and captured in June St. Lawrence River, and the U.S. Pacific coast. 2006. Because other known crab species in this size range and vicinity are not easily confused with the mitten crab, these appear credible Collection Records and Description records, occurring up to ~90km south of the first two specimens. The first reported mitten crab was captured 9 June In summary, we report at least two different 2006 at the mouth of the Patapsco River, Mary- specimens of E. sinensis captured in Chesapeake land in the Chesapeake Bay (39º09'25"N, Bay in two different years, and both were deposi- 76º24'13"W) by J. Delp. The mitten crab was ted in collections of the National Museum of caught in a baited crab trap at approximately 5m Natural History, Smithsonian Institution, depth along with several individuals of the native Washington DC (USNM 1092253; second number blue crab Callinectes sapidus Rathbun, 1896 (J. pending). The two specimens, as well as the other Delp, personal communication). This first mitten two unconfirmed reports, were from low salinity crab was frozen and delivered to us for exami- (5-15 psu) waters of the upper Chesapeake Bay. nation on 21 July 2006. The specimen is male, No specific environmental measures were taken at 63mm carapace width (Figure 1). the specific time and place of these collections. 138 First records of Eriocheir sinensis for Chesapeake Bay Figure 1. Eriocheir sinensis H. Milne Edwards, 1853, male specimen 63mm carapace width (third pereopods missing), captured 9 June 2006 at mouth of Patapsco River, Maryland, Chesapeake Bay (39º09'25"N, 76º24'13"W), by J. Delp: A, dorsal view; B, ventral view There are at least two likely mechanisms for Discussion the initial transfer of mitten crabs to the Chesapeake. Commercial ships are known to At the present time, we do not know whether transfer marine organisms across ocean basins in additional mitten crabs occur in the Chesapeake their ballast tanks and associated sea chests Bay watershed or whether reproduction is (Carlton and Geller 1993, Coutts et al. 2003). This occurring here. It is possible that (a) only a small mechanism can deliver larval and postlarval crabs number of crabs were present in the Chesapeake to the Chesapeake from anywhere in the world. It and (b) the existing crabs could have originated is noteworthy that northern Europe is a dominant by transfer instead of local reproduction. source for overseas ships arriving and discharging 139 G.M. Ruiz et al. ballast water to ports of the Chesapeake Bay breaks” (Herborg et al. 2003, U.S. National (Carlton et al. 1995, Smith et al. 1999). Not only Management Plan 2003, Rudnick 2003, 2005). do incoming ships often originate from within the Moreover, the crabs’ occurrence in freshwater known European range of E. sinensis, but they may avoid detection, if it is not yet abundant, due also arrive to the Port of Baltimore in the to relatively low sampling effort in appropriate Patapsco River, where the mitten crabs were habitats of the extensive freshwater tributaries found. Ships also arrive from Pacific ports where surrounding the Chesapeake. mitten crabs occur, and could deliver E. sinensis The mitten crab is considered to pose a signifi- to the Chesapeake, but the reported volume of cant risk of ecological and economic impacts in ballast water discharged locally from this region North America. As reviewed in the U.S. National in recent years (1999-2004) was < 1% of that Management Plan (2003), there is evidence that E. from the northern European ports where this sinensis can (a) impact water supply and manage- species occurs (NBIC 2005). ment, (b) increase erosion and slumping of banks In addition to shipping, mitten crabs could have and levees, (c) impact fisheries by interference been imported to the Chesapeake region for food with gear, and (d) cause damage to aquatic and released. Mitten crabs are eaten in Asia and vegetation by feeding. Although the crab may also Europe, and production of mitten crabs in China have significant effects at population, community, alone was estimated at 380,000 tons/year in 2003, and ecosystem levels, these are not well increasing more than 40 times that in 1991 (China documented.