Southeast Ecological Science Center
Some species of snakeheads have been imported for several decades for the aquarium fish trade. In the past two decades, however, snakeheads have also been imported to the U.S. for sale in certain ethnic markets that sell livefood fishes and some restaurants that hold live fishes in aquaria for customer selection. In most states and the District of Columbia, such importation and sale is legal, but there have been violations in at least six states where possession and sale of live snakeheads is illegal. Until recently, the live-food fish pathway for potential introduction of live fishes into U.S. waters was largely overlooked. Because Channa maculata (misidentified as C. striata) and other eastern Asian food fishes (common carp, Cyprinus carpio; oriental weatherfish, Misgurnus anguillicaudatus; whitespotted clarias, Clarias fuscus; and swamp eel, Monopterus albus) were introduced from China into Hawaii before 1900, doubtlessly encouraged and perhaps initiated by Asian immigrants (Maciolek, 1984), this pathway should have been of concern.
Imports of snakeheads into the U.S. have been increasing in recent years (table 5). Importation records unfortunately report quantities either in numbers or by weight, but not both. Hence, the two columns (Number of individuals, Number of kilograms) in table 5 consist of 51,233 fish and an additional 22,208 kg of snakeheads. Furthermore, records do not provide a detailed breakdown of species imported or indication of the intended reason for importation (pet trade or live-food fish markets). Moreover, these records are probably incomplete (Marshall Myers, personal commun., 2001) and may represent only part of the total number/weight of imported snakeheads. This, coupled with not knowing how much of the weight represents small snakeheads and juveniles of larger species destined for the aquarium fish trade versus market-size, larger fish, makes projecting the total number of individuals a precarious guess at best.
Table 5-U.S. importations of live snakeheads (Channidae, all species)
Sources of imported snakeheads are varied (table 6). Again, these records are probably incomplete, but China is clearly the major exporter of live snakeheads. As in table 5, there is no breakdown by species.
The number of species that have been imported for the aquarium fish trade or the live-food fish trade could not be determined. Nevertheless, Channa argus is the most widely cultured snakehead in China (Fang Fang, personal commun., 2002), and has been available for sale in ethnic live-food fish markets in New York (James Stephen Lee, personal commun., 2001) and St. Louis, Missouri (Leo Nico, personal commun., 2002). A total of 80 live individuals in transit to Seattle were confiscated in Blaine, Washington, in 2001 (Ted Pietsch, personal commun., 2001; Mike Williams, personal commun., 2003), and others were seized from markets in Houston, Texas (Howells and others, 2002), Miami and Pembroke Pines (Florida Fish and Wildlife Conservation Commission, 2001), and Orlando, Florida. Snakeheads had been illegal in California, Florida, Texas, Washington, and 10 other states for many years prior to July 2002.
Table 6-Origin of snakehead shipments (Channidae, all species) during the past 5 or
The first specimen of this species to have been captured from U.S. waters was taken by electrofishing in Spiritwood Lake, a reservoir north of San Bernadino, California, in 1997. Two individuals were caught by angling in the St. Johns River, below Lake Harney, Seminole and Volusia Counties, Florida, in 2001 (with three more reported as having been caught nearby); another was captured by electrofishing in Newton Pond, Worcester County, Massachusetts, in late 2001. The discovery of an established population of this species in a pond in Crofton, Anne Arundel County, Maryland, proved that this species was capable of invading U.S. waters. In July 2002 C. argus was being sold in a live-food fish market in Orlando, Florida. That market was raided by FFWCC agents who confiscated several specimens. Northern snakeheads were reported to be in culture in Arkansas, and this may or may not have been a source of northern snakeheads in Florida. Channa argus was likely available in live-food fish markets in Boston, although two snakeheads purchased there in late 2001 by Karsten Hartel were later identified as C. maculata. Live-food fish markets in Vancouver, British Columbia, also sold C. argus (Margarita Reimer, personal commun., 2002).
In conclusion, Channa argus is known to have been the most widely available snakehead in North American live-food fish markets, followed by C. maculata. Channa marulius was also available in New York City live-food fish markets (Leo Smith, personal commun., 2002). There have been no reports of C. striata being available for sale in live-food fish markets in the contiguous U.S., even though it is considered the most important snakehead used for food in southeastern Asia and is being cultured in Hawaii. Nevertheless, a freshly killed C. striata was purchased from an oriental market in San Diego, California, on July 29, 2002 (Richard Rosenblatt, personal commun., 2002). There was no cloudiness in the eyes of the specimen, indicating that it had never been frozen and may have been kept in a live fish tank, perhaps on the premises of the market, until a very short time before being placed on ice for sale. The specimen was deposited in the fish collection of Scripps Institution of Oceanography (SIO 64-228). Channa striata is being sold in a market in Honolulu, Hawaii (Pam Fuller, personal commun., 2002).
Another observation from importation data shows that imports of live snakeheads from Ghangzhou and Shenzhen, both in Guangdong Province, China, began to increase in the latter part of 2001 and accounted for the majority of imports through May 2002. Channa argus is not native to southern China. Therefore, importation data suggest that many snakeheads imported during late 2001 well into 2002 may have been C. maculata, destined for the live-food fish trade.
At least 14 states specifically prohibited possession of live snakeheads (table 7) prior to the discovery of an established population of northern snakeheads in a pond in Crofton, Anne Arundel County, Maryland, which was eradicated in September 2002. Since then, the states of Arkansas, Connecticut, Illinois, North Carolina, Rhode Island, Pennsylvania, South Carolina, Tennessee, and Virginia have made possession of live channids illegal (fig. 5). Indiana Department of Natural Resources approved emergency fisheries regulations on November 22, 2002, that bans possession of snakeheads effective December 1, 2002. Kansas Department of Wildlife and Parks prohibited possession of snakeheads in early 2003.
The U.S. Fish and Wildlife Service published a proposed rule to list the family Channidae (snakehead fishes) as injurious wildlife in the Federal Register on July 26, 2002 (67 FR 48855) under the Lacey Act (18 U.S.C. 42). The final rule banning importation and interstate transport of live snakeheads was published in the Federal Register on October 4, 2002 (67 FR 62193). This ruling does not affect possession or sale of live snakeheads in states that do not specifically prohibit them, or importation of dead snakeheads refrigerated or frozen for sale as food fishes into states where possession of live snakeheads is illegal. Nevertheless, despite the Federal rule and a long-standing state prohibition, several live Channa argus were confiscated by U.S. Fish and Wildlife Service Inspectors in California as recently as July 2003.
Figure 5-States prohibiting possession of live snakeheads as of November 2002. - click to enlarge
Prior to 2002, there were illegal activities involving snakeheads in states that prohibited their sale or possession. A total of 80 live Channa argus, destined for markets in Seattle, was discovered in 2001 on a truck from British Columbia. Specimens of C. micropeltes and C. marulius were confiscated from pet shops in the Los Angeles area, southern California, in the past 2 years. Channa argus was confiscated from live-food fish markets in Miami, Orlando, and Pembroke Pines, Florida, and Houston, Texas, in 2001. Illegal traffic in pet snakeheads, involving mostly C. bleheri, was discovered in Alabama and Kentucky in the past 2 years. It has been suggested that these snakeheads came from a distributor in Atlanta, Georgia, a state where snakehead possession is also illegal.
Temperature is the most important environmental factor that would determine potential range of snakeheads in the United States. Because there are few data providing thermal tolerance ranges for snakeheads, potential range must be inferred from distribution within native ranges (fig. 6). The family Channidae contains 10 species that are strictly tropical and, if introduced, would survive in only the warmest waters, such as extreme southern Florida, perhaps parts of southern California and Hawaii, and certain thermal spring systems and their outflows in the American west. Another four species can be considered
tropical to subtropical, indicating a similar potential range of distribution as for tropical species, but with a greater likelihood of survival during cold winters and more northward limits. One is subtropical. Another 11 snakeheads (3 that appear to be species complexes) can tolerate tropical or subtropical to warm temperate conditions, indicative of species that could survive in most southern states. One is warm temperate, and another is warm temperate to cold temperate (Channa argus has a temperature range of 0-30 oC). In summary, there are no waters in the United States that, based on temperature, would preclude some member(s) of the family Channidae from becoming established.
Figure 6-Thermal range of snakeheads (Channidae)