428 



Ndii-iiativt' Spciii'x — Old- Liiint; Resources 



logs from New Zealand and Siheiia endanger 

 Pacific Northwest forests through forest pests 

 hitchhiking in the bark and wood (J. Lattin. 

 Oregon State University, personal communica- 

 tion). It is clear that international cargo traffic 

 must be monitored to reduce the spread of non- 

 native species. 



Although this section only briefly mentions 

 disease, it may be one of the most important 

 problems caused by non-native species. After 

 Columbus landed in the New World, for exam- 

 ple, 95% of the Native tribes became extinct 

 because their people were susceptible to 

 European microbes (Diamond 1992). Likewise, 

 exotic diseases have devastated populations of 

 aquatic organisms worldwide, killed many 

 native trees, and exterminated much of Hawaii's 

 avifauna. Non-native species are the primary 

 vector for these diseases; for instance, the 

 spread of fish diseases worldwide resulted from 

 the unprecedented transfer of non-native fishes 

 for hatchery production. 



It is clear from the small sampling of articles 

 here that changes caused by non-native species 

 are widespread and profound. We present dif- 

 ferent case histories representative of a myriad 

 of management problems today. New problems 

 continually arise, however, because humans 

 deliberately and accidentally release non-native 

 species and encourage their invasion through 

 massive disturbances of the landscape, thereby 

 mitigating against native species" resistance to 

 invaders by stressing native populations. These 

 articles should make it clear that although non- 

 native species are costly to manage, manage 

 them we must. 



References 



Diamond. J. 1992. The arrow of disease. Discover 13 



(]0);64-73. 

 Lassuy. D.R. 1994. Aquatic nuisance organisms: setting 



national policy. Fistieries (Bethesda) 19(4):14-17. 

 Mack, R.N.. and J.N. Thompson. 1982. Evolution in step 



with few large, hooved mammals. American Naturalist 



119:7.'^7-773' 



Non-native 

 Aquatic 

 Species in the 

 United States 

 and Coastal 

 Waters 



by 



Christina Bjergo 



U.S. Coast Guard 



Charles Boydstiin 



National Biological Senice 



Michael Crosby 



Steve Kokkanakis 



National Oceanic and 



Atmospheric Administration 



Richard Sayers, Jr. 

 U.S. Fish and Wildlife Service 



Since the European colonization of North 

 America, many non-native aquatic species 

 have been introduced into the United States and 

 adjacent waters. The harm caused by recent 

 introductions, particularly by the zebra mussel 

 (Dreissemi polymorpha). and concern about a 

 possible increase in the number of unintention- 

 al introductions resulted in passage of the 

 Nonindigenous Aquatic Nuisance Prevention 

 and Control Act of 1990. This statute mandates 

 development and implementation of a compre- 

 hensive national program to prevent and 

 respond to problems caused by the unintention- 

 al introduction of nonindigenous aquatic 

 species into waters of the United States. This 

 article presents an overview of nonindigenous 

 aquatic species, a summary of potential path- 

 ways of introduction, and response strategies. 



Presence and Distribution 



Non-native aquatic species in the United 

 States and coastal waters include species from 

 many plant and animal taxa and span the entire 

 country (Figure). That this problem is extensive 

 is clear by the numbers: 139 nonindigenous 

 species are now established in the Great Lakes 

 (Mills et al. 1993): 32 species of nonindigenous 

 marine organisms were collected from one 

 small Oregon estuary (Carlton 1991); 96 non- 

 indigenous sponges, worms, crustaceans, and 

 other invertebrates are now found in San 

 Francisco Bay (Carlton 1979); and more than 

 half of Hawaii's free-living species are non- 

 indigenous (U.S. Congress 1993). The rate of 

 nonindigenous species" introductions into the 



Great Lakes has increased in spurts since 1810, 

 largely in response to an expanding human pop- 

 ulation, development in the basin, and increased 

 transoceanic shipping. 



Benefits and Costs 



Nonindigenous aquatic species have been 

 both beneficial and problematic. Beneficial 

 aspects include enhancing recreational opportu- 

 nities such as sport-fishing; providing reliable, 

 high-quality food via aquaculture and maricul- 

 ture; and aesthetically improving the human 

 environment via the aquarium industry. 

 Recreational fishing contributed an estimated 

 $24 billion in expenditures and $69.4 billion in 

 economic output in 1991 (SFI 1994). 



Problems associated with nonindigenous 

 aquatic species are priinarily related to ecologi- 

 cal issues, such as their effects on indigenous 

 species, and financial issues, such as economic 

 losses caused by biofouling of water-intake 

 pipes. For example, nonindigenous species 

 were cited as a contributing cause in the extinc- 

 tion of 27 species and 13 subspecies of North 

 American fishes over the past 100 years (Miller 

 et al. 1989). Federal, state, and local govern- 

 ments, as well as industry, have often borne sig- 

 nificant costs related to nonindigenous aquatic 

 species. From 1906 to 1991. estimated losses 

 associated with 79 aquatic and terrestrial non- 

 indigenous species were roughly $97 billion 

 (Table 1), and worst-case estimates for 15 

 potential high-impact nonindigenous species 

 project future economic losses of another $134 

 billion (U.S. Congress 1993). 



