Aquatic Nuisance Species in the New YorkState Canal and Hudson River Systems andthe Great Lakes Basin: An Economic andEnvironmental Assessment

DAVID PIMENTEL

Agriculture and Life SciencesCornell University5126 Comstock HallIthaca, New York 14853, USA

ABSTRACT / A total of 154 aquatic alien species have in-vaded the New York State Canal and Hudson River sys-tems and a total of 162 aquatic species have invaded theGreat Lakes Basin. Some of these invasive species arecausing significant damage and control costs in both

aquatic ecosystems. In the New York State Canal andHudson River systems, the nonindigenous species arecausing an estimated $500 million in economic losses eachyear. The economic and environmental situation in theGreat Lakes Basin is far more serious from nonindigenousspecies, with losses estimated to be about $5.7 billiondollars per year. Commercial and sport fishing suffer themost from the biological invasions, with about $400 millionin losses reported for the New York State Canal and Hud-son River systems and $4.5 billion in losses reported for theGreat Lakes Basin.

Approximately 50,000 biological invading speciesare estimated to have been introduced to the UnitedStates (Pimentel and others 2000; Pimentel 2002) and Iestimate the number of aquatic and terrestrial non-indigenous species in New York State to be severalthousand. This number includes all our crops andlivestock (more than 99% introduced, plus introducedmicrobe species). Other beneficial species introducedinto New York State include biological control species,sports fish, and beneficial organisms used in foodprocessing (Pimentel, unpublished data).

The problem of invasive alien species is growingrapidly because of a rapidly growing world populationand more people traveling worldwide (Pimentel 2002).In addition, more goods are moving between countrieswith globalization, and invasive species can be easilytransported. One of the most serious problems withpeople and goods moving between countries is thatsome inspectors and specialists who are responsible forpreventing the introductions of alien species into theUnited States lack training and knowledge concerning

the environmental and economic threat of invasivespecies.

This is well illustrated by an experience that I hadwhile conducting research with the US Public HealthService in Puerto Rico. The head of a zoo in Ohiorequested that I send him an Indian mongoose. I waswilling to ship the mongoose to Ohio, but had con-cerns because of environmental and public health risksassociated with the mongoose. This concern led me toask permission from various government agencies,including the US Public Health Office in Puerto Rico,APHIS (Animal and Plant Health Inspection Service),and the Agricultural Research Service of the USDepartment of Agriculture. All gave me permission. Iwas not satisfied and checked further with a specialistin Washington, DC; I was informed that there was aspecial paragraph that indicated that the Indian mon-goose could not be introduced into the United Statesmainland alive for any purpose. This experience con-firmed to me that knowledgeable specialists in thegovernment are not well educated concerning the risksof introducing alien plant, animal, and microbe speciesinto the United States. The public also lacks knowledgeof the hazards of bringing exotic plant, animal, andmicrobe species into the United States. The public isprimarily responsible for preventing the introductionof exotic species into the United States: however, theyneed to be educated concerning the serious publichealth, environmental, and economic threats that are

KEY WORDS: Aquatic; Invasive species; Environment; Economic;New York State; Great Lakes

Published online May 17, 2005

*Author to whom correspondence should be addressed; email:

dp18@cornell.edu

Environmental Management Vol. 35, No. 5, pp. 692–701 ª 2005 Springer Science+Business Media, Inc.

DOI: 10.1007/s00267-004-0214-7

associated with the introduction of alien plants, ani-mals, and microbes.

Although most of the public and many inspectorslack specific knowledge of invasive exotic species, sev-eral biological invading species cause major economicand environmental harm to aquatic ecosystems, agri-culture, forestry, and other ecosystems. Estimating thefull extent of the economic and environmental dam-ages caused by exotic species in New York State’saquatic ecosystems is difficult because all of the aquaticspecies of plants, animals, and microbes have not beendescribed and/or little is known about their ecology.Therefore, estimating the economic and environmen-tal impacts that are associated with alien species in NewYork State will be difficult. Nevertheless, sufficient dataare available to quantify some of the impacts in theNew York State Canal and Hudson River systems andthe Great Lakes Basin.

The New York State Canal and Hudson River systemsconnect the waters of Lake Erie, Lake Ontario, LakeChamplain, the Finger Lakes of Central New York, theMohawk River, and the Hudson River. The New YorkState Canal System (NYSCS) stretches 524 miles acrossthe state of New York, and with the Erie Canal and threelateral canals, Oswego, Cayuga–Seneca, and Champ-lain, it connects the waters of Lake Erie, Lake Ontario,Lake Champlain, the Finger Lakes of New York State,the Mohawk River, and the Hudson River system (Smith1985). The minimum depth of the current NYSCS is 12ft and the minimum width varies from 44 ft in the locksto 200 ft in the canal sections of the rivers (Smith 1985).Historically, the New York State Canal and HudsonRiver systems have played an important role in thetransfer of species between the Hudson River Basin andthe Great Lakes Basin (Mills and others 1993). Theconstruction of the canals, connecting watersheds forcommerce, transport, recreation, and water supply,provided an effective mechanism for the introductionand dispersal of aquatic nonindigenous species. Theobjective of this project is to assess the economic andenvironmental impacts of damaging aquatic nonindig-enous species in the New York State Canal and HudsonRiver systems and the Great Lakes Basin.

Stakeholders

Both the New York State Canal and Hudson Riversystems and the Great Lakes Basin are tremendouslyvaluable resources. The two most valuable stakeholderunits are the agriculture and tourism industries. Someaspects of agriculture probably have a marginal rela-tionship to both the New York State Canal and HudsonRiver systems and the Great Lakes Basin. In the esti-

mates provided below, the New York State Canal andHudson River systems are taken together because noestimates were available for them individually. A thirdimportant stakeholder is the electric power industryand it was included in both aquatic systems because theelectric power industry directly uses water for coolingand other purposes from both aquatic ecosystems. Thevalue of other industries was not included because of alack of data. The value of the many restaurants andother recreational units were assumed to be a part oftourism benefits.

There was some overlap among commercial fishing,sport fishing, and boating, but there were no data thatreported how much of an overlap existed.

Exotic Aquatic Species in the United Statesand Economic Impacts

The estimated annual damage and/or control costassociated with some aquatic nonindigenous speciesintroduced in the United States is $14.2 billion (Ta-ble 1). The only aquatic plants for which there are lossdata available include Eurasian watermilfoil (Myrio-phyllum spicatum), purple loosestrife (Lythrum salicaria),and water chestnut (Trapa natans). The total for these

three aquatic plants is slightly more than $800 million

per year.

The pigeons (Columba livia) and starlings (Sturnusvulgaris) were included, but they are not totally asso-ciated with aquatic ecosystems. The total damages andcontrol costs for pigeons and starlings were estimatedto be $1.9 billion per year (Table 1).

The damages and control costs for invasive fishspecies in the Great Lakes Basin and other aquaticecosystems in the United States total $5.4 billion peryear. Most (or $4.5 billion) loss was associated with theGreat Lakes (Table 1). The remaining $0.9 billion wasfor the remainder of the United States.

Mollusks cost the nation an estimated $2 billion peryear (Table 1). This cost is for both damages andcontrol costs mostly associated with electric powerplants and water supply units in cities and towns. Noestimates exist for environmental damages to beaches,fishing, and boating from these mollusks.

The only data for other invading aquatic inverte-brates in the United States were for the spiny waterflea(Bythotrepes longimanus), fishhook waterflea (Cercopagispengoi), green crab (Carcinus maenas), and mosquitoes(Culex and Aedes species) (Table 1). The green crab wasestimated to cost about $100 million per year (Holmes2003) (Table 1). Most of the estimated damages andcontrol costs for the United States were for the mos-

Aquatic Nuisance Species Assessment (Northeast) 693

quitoes, $1.5 billion per year (Table 1). For microbesassociated with aquatic ecosystems, the West Nile viruswas the only disease microbe identified with associateddamage and control costs. These were estimated to be$2.5 billion per year (Table 1).

Exotic Species in the New York State Canaland Hudson River Systems and the GreatLakes Basin

The total number of exotic species in the New YorkState Canal and Hudson River systems is 154 (Table 2).The number of exotic species displayed in Table 2 doesnot add up to the 154 species, because the data comefrom different sources. The algae (nonvascular plants),vascular aquatic plants, fishes, and invertebrates makeup 90% of the invasive species. Each organism group hasapproximately the same number of species. The totalnumber of native species in this canal and river system isestimated to be 524, but this is probably a significantunderestimate. The number of invertebrates is probablycloser to 1000. The total number of introduced specieshas been increasing (Mills and others 1997).

Ricciardi (2001) and Mills and others (1993) esti-mate that 162 exotic aquatic species that have beenintroduced into the Great Lakes Basin (Table 3). Theplants, invertebrates, fishes, and algae make up most ofthe exotic species, with a small number consisting ofbirds and pathogen/parasites. The exotic fishes andplants are having the greatest environmental and eco-nomic impacts in the Great Lakes.

The numbers of exotic species in the Great Lakes andNew York State Canal and in the Hudson River systemsdo not differ greatly, with the Great Lakes total being 162and the New York State Canal and Hudson River systemswith a total of 154 (Tables 2 and 3). The numbers ofinvasive species have been increasing in both ecosystems.

The rate of aquatic exotic species introductions hasbeen increasing in the Great Lakes Basin each year

Table 1. Estimated annual costs associated withsome aquatic nonindigenous species introduced intothe United States in millions of dollars

Nonindigenous organismDamages and/or control costs ($)

PlantsEurasian watermilfoil 400a

Purple loosestrife 229b

Water chestnut 200c

BirdsPigeons 1,100d

Starlings 800d

Fishes 5,400e

Great Lakes fishery 4,500f

MollusksZebra and quagga mussel 1,000g

Asian clam l,000h

InvertebratesSpiny waterflea 5i

Fishook waterflea 5i

Mosquitoes 1,500j

Green crab 100k

MicrobesWest Nile virus 2,500l

Total 14,239

aControl of Eurasian watermilfoil in Loon Lake (Washington) is re-

ported to be 4000 ha each year (Parsons and others 2001). The esti-

mated cost of control per hectare is $2000 (Maine 2003). It is assumed

that 200,000 ha of milfoil are controlled in the United States each

year at a cost of $400 million per yearbData from USGS (1999).cWater chestnut control in the Lake Champlain Basin is reported to

be $3 million per year (NYDEC, Army and KYS Canal Corporation

2000). It is assumed that 100,000 ha are treated each year at a cost of

$200 million per year.dData from Pimentel and others (2000).eSea Grant (2002a) and Standing Committee on Fisheries and Oceans

(2003) estimate that the loss to Great Lake fishery due to invasive

species is $4.5 billion per year. An additional $1 billion per year is

estimated for the impact of other invasive fish species in other aquatic

ecosystems in the United States.fThe $4.5 billion loss per year in the Great Lake fishery alone.gData from Sea Grant (2002b) and CRC Reef Research (2003).hPimentel and others (2000).iEstimated.jJust cleaning up and disposing of scrap tires that were breeding sites

for mosquitoes in Maryland was estimated to cost $11 million per year

(DLS 2000). Assuming that 50 states invested in a similar manner and

this makes up only one-third of total mosquito control, then the

estimate for mosquito control in the United States is conservatively

$1500 million per year.kData from Holmes (2003).lNew York State invests about $35 million per year in West Nile virus

control (Governor 2000). Assuming that all 50 states have already or

will invest in West Nile virus control, the total is $1500 million per

year. In addition, there were 4156 cases of West Nile virus infections

in humans and 284 deaths in 2002 (CDC 2003). Assuming $3.7 mil-

lion per death as suggested by the EPA (Weinberg 2003), the total

cost is more than $1 billion per year.

Table 2. Exotic species in the New York State Canaland Hudson River systems

Hudson River Total species Total exotic species

Algae 100a 33a

Aquatic plants 197b 33b

Invertebrates 104b 25b

Birds 24b 4b

Fishes 99b 29b

Total 524 154c

aEstimated based on the data of Margraves and Marana (2002) on the

number of potentially toxic or harmful algae that total 46 species.bData from Mills and others (1997).cData from ANS (2003).

694 D. Pimentel

since about 1810 (Figure 1). This confirms a similartrend related to aquatic species in the San FranciscoBay, where it is reported that an estimated 234 alienspecies have been introduced into the bay since 1851.It took more than 100 years for 117 alien species to beintroduced into the San Francisco Bay, but only 35years (1965–2000) for another 117 species to beintroduced (Cohen and Carlton 1998).

Currently, one of the greatest exotic species con-cerns for the Great Lakes are two types of Asian carp.Asian carp are present in the Illinois River and arepoised to gain entrance to Lake Michigan (Moy 2003).As of December 2003, the bighead carp (Hypophthal-michthys nobilis) is closer to the barrier (within 28 miles)

than the silver carp (Hypophthalmichthys molitrix) (within66 miles) (Moy, University of Wisconsin Sea Grant

Institute, personal communication, 2003). Currently,

about $1.75 million per year is being spent for one

electric barrier in an attempt to prevent these carp spe-

cies from invading Lake Michigan (Moy 2003). Another

barrier is in the design stage.

Environmental and Economic Impacts ofBiological Invaders in the New York StateCanal and Hudson River Systems and theGreat Lakes Basin

The total environmental and economic impacts(damage and control costs) of biological invaders in

the New York State Canal and Hudson River systemswere currently estimated to be nearly $500 millionper year (Table 4). Approximately 80% of these costswere associated with the losses in commercial andsport fishing. The commercial fishery losses were dueto reduced fish production and reduced number offishers. Sports fisherman reduced their activity be-cause fishing was relatively poor. After fishery im-pacts, the largest impact was on public health frompathogens and parasites, primarily the West Nilevirus, with an estimated $40 million per year (Ta-ble 4). The impacts ($20 million) from mussels andother invertebrates were on industry’s use of water,especially electric power plants and public watersupply systems. About $17.5 million in lost revenuewas suffered by the tourism stakeholders and most ofthis was due to other invertebrates, especially mos-quitoes (Table 4). The other aquatic invaders causedproblems, but they were relatively minor in compar-ison (Table 4).

The New York State Canal and Hudson River sys-tems have been suggested as one of the routes for theinvasion of the Great Lakes by the sea lamprey (Pet-romyzon marinus) and perhaps other invaders (Mills and

others 1992). The sea lamprey apparently moved up the

Hudson River, into the New York State Canal, and

eventually into Lake Erie and/or Lake Ontario and the

other Great Lakes.

Table 3. Exotic species in the Great Lakes Basin

Great Lakes Total species Total exotic species

Algae 379a 25b

Plants 1000c 59b

Invertebrates 4200d 33e

Pathogens/parasites — 3b

Birds 131f 4g

Fishes 250h 48i

Total 5960 162j

aData from EPA (2002).bData from Leach and others (1999).cData from Earth Systems Education (2000).dThere are an estimated 750,000 species of plants, animals, and mi-

crobes in the United States (Pimentel and others 2000), and of this

group, about 500,000 are invertebrates. Based on the area of the

Great Lakes Basin, �4200 species of invertebrates are present. One

study of aquatic species of invertebrates in the Great Lakes Basin

reports on some of the species in the area that total 665 species

(USGS 2002).eData from Mills and others (1993).fData from Jannereth (2002).gData from Pimentel and others (2000).hData from NOAA (2002).iData from Coon (1999).jData from Mills and others (1993) and Ricciardi (2001).

Figure 1. Cumulative number of invaders of 162 species inthe Great Lakes Basin starting in 1810 until 1999 (afterRicciardi 2001).

Aquatic Nuisance Species Assessment (Northeast) 695

Table 4. Environmental and economic impacts (damage and control costs) of biological invaders in the NewYork State Canal and Hudson River systems in millions of dollars

Functional group

Stakeholder group Fish AlgaeAquaticPlants Mussels

OtherInvertebrates Birds

Pathogensand parasites Total

Landowner, agriculture 2a 3b 5Public health 40c 40Tourism 4d 0.5e 10f 1g 2h 17.5Electric industry 10i 10j 20Commercial fishing 200k 1l 0.5m 2n 0.5o 204Sport fishing 200p 1q 1r 2s lt 206Boating 2u 0.5v 0.5w 3Transport 0Bird/wildlife watchers 1x 2y 1z 4Total 400 8 12.5 25.5 5 47.5 498.5

aDamages to agriculture and control costs associated with starlings

and pigeons (Pimentel and others 2000).bWest Nile virus infections and deaths in some of the 182,000 horses

in New York State (Davidsen 2003); estimate based onthe fact that

New Jersey reported $6 million in losses each year (AHC 2003).cAn estimated 2 million people in New York State live along the

Hudson River and New York State Canal system and are exposed to

mosquitoes transmitting West Nile virus. The cost of spraying for

adult mosquito control is reported to be $14.40 per person (Hansen

2003); however, it is estimated that only two-thirds of the area is

treated—thus, about $20 million. In addition, there were 82 cases of

West Nile virus infections, plus 4 deaths in New York (CDC 2003).

Assuming $3.7 milliontt per death as suggested by the EPA (Weinberg

2003) plus hospitalizations, outpatients, and lost work, the total cost

of this human health problem is $20 million per year (Pimentel,

unpunished data).dWeeds interfere with swimming and the aesthetics of the environ-

ment. The cost of either mechanical or chemical weed control per

hectare is �$2000 (NYSCC 2002; UMN 2002; Bouchard 2003; SePRO

2003) and it is estimated that about 2000 ha are cleared of weeds each

year.eZebra and quagga mussels cover the bottom of some beaches and

cause cuts on swimmers’ feet (WNR 2001). The estimated impact is

$500,000 per year.fMosquito control costs about $14.40 per person (Hansen 2003). It is

estimated that about 2 million tourists visit the Hudson River and New

York State Canal systems each year and �700,000 people visit tourist

locations requiring mosquito control operations.gBird populations are being infected by the West Nile virus and re-

duced in number (Weiss 2002). The negative impact on tourism is

estimated to be $1 million per year.hSome spraying is carried out for the protection of tourists from the

West Nile virus and this is estimated to be about $2 million per year.

See footnote f.iZebra and quagga mussel damage and control costs to electric power

plants and water supply plants are an estimated $10 million per year

in the Hudson River and New York State Canal systems. Zebra and

quagga mussel damage and control cost the United States about $1

billion per year (Pimentel and others 2004; CRC Reef Research 2003).

A single nuclear power plant spends on average an additional

$825,000 per year for zebra mussel control (Exotics 2003).jAsian clam damages and control in the United States are estimated to

cost about $1 billion per year (Pimentel and others 2000). Use of

water by power plants in the Hudson River and New York State Canal

systems requires an estimated $10 million per year to control the

Asian clam.

kInvasive fish species in the Hudson River and New York State Canal

systems are causing an estimated $200 million in damages to com-

mercial fisheries each year. This is based on the impact of invasive

species of fish and other organisms in the Great Lakes, which is

estimated to be about $2.5 billion in damages and control costs per

year (Sea Grant 2002a).lWeeds interfere with some commercial fishing operations. The cost

of either mechanical or chemical weed control per hectare is

approximately $2000 (NYSCC 2002; UMN 2002; Bouchard 2003; Se-

PRO 2003) and it is estimated that about 500 ha are cleared of weeds

each year.mZebra and quagga mussels interfere with some aspects of commer-

cial fishing, such as buildup of mussels on the hulls and motors of the

boats. Increased drag and cleaning of the mussels is estimated to cost

$500,000 per year.nNuisance and control costs of the Asian clam and mosquitoes are

estimated to cost the fishing industry an estimated $2 million per year.

The Asian clam causes about $1 billion in damages and control costs

each year in the United States (Pimentel and others 2000).oA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $500,000 per year

based on 35,000 people exposed and $15 per person for spraying.pInvasive fish species in the Hudson River and New York State Canal

systems are causing an estimated $200 million in damages to sports

fishing each year. This estimate is based on the impact of invasive

species of fish and other organisms in the Great Lakes, which is

estimated to be about $2.5 billion in damages and control costs per

year to commercial fisheries (Sea Grant 2002a).qWeeds interfere with some sports fishing operations. The cost of

either mechanical or chemical weed control per hectare is approxi-

mately $2000 (NYSCC 2002; UMN 2002; Bouchard 2003; SePRO

2003) and it is estimated that about 500 ha are cleared of weeds each

year associated with sports fishing.rZebra and quagga mussels interfere with some aspects of sports

fishing, such as buildup of mussels on the hulls and motors of boats.

Increased drag and cleaning of the mussels is estimated to cost $1

million per year.sNuisance and control costs of the Asian clam and mosquitoes are

estimated to cost sports fishing an estimated $2 million per year. The

Asian clam causes about $1 billion in damages and control costs each

year in the United States (Pimentel and others 2000).tA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $1 million per year

based on 65,000 people exposed and $15 per person for spraying.uWeeds interfere with some boating operations. The cost of either

mechanical or chemical weed control per hectare is approximately

696 D. Pimentel

The total environmental and economic impacts(damage and control costs) of biological invaders inthe Great Lakes Basin are currently estimated to benearly $5.7 billion per year (Table 5). This is morethan 10 times the loss reported for the stakeholders inthe New York State Canal and Hudson River systems(Tables 4 and 5). Similar to the New York State Canaland Hudson River systems, approximately 80% of thelosses were associated with commercial and sport fish-ing losses. About $4.5 billion of the $5.7 billion wereassociated with fishery losses (i.e., reduced populationof important commercial and sports fish).

The next largest cost after the fishery losses was the$620 million in public health effects from the WestNile virus infections (Table 5). About 2067 cases ofWest Nile virus infections, which included 155 deaths,were reported in the 7 states (New York, Pennsylvania,Ohio, Michigan, Wisconsin, Illinois, and Minnesota) in2003 in the Great Lakes Basin (CDC 2003). No dataexist on the distribution of the human West Nile casesin the seven states.

The fourth largest cost to stakeholders wasapproximately $500 million per year associated withpower plants and water supply facilities and mostof this cost was associated with the zebra (Dreissenapolymorpha) and quagga (Dreissena bugensis) mussels(Table 5). Tourism suffered approximately $17.5million per year, primarily from mosquito problems.The remaining stakeholders, who suffered lossesranging from $5 to $3 million per year, includedboaters, bird/wildlife watchers, agriculture, and shiptransport (Table 5).

Control and Prevention of Aquatic Invadersinto New York State Canal and Hudson RiverSystems and the Great Lakes Basin

Of the 50,000 biological invader species in theUnited States, only 4 pest species have been extermi-nated. The species exterminated include: Mediterra-nean fruit fly (Ceratitus capitata), citrus canker, smallpox, and polio (OTA 1993). Although the Mediterra-nean fruit fly and citrus canker have been extermi-

nated in the past, both have invaded the United Statesagain (Pimentel 2002).

Discussions are underway on how we can preventexotic species from being introduced into the UnitedStates. One approach for preventing the invasion ofaquatic exotics is to control the dumping of ballastwater in US waters. Despite the discussions and currentregulations, approximately 58 million gallons of vari-ous types of ballast water are discharged each day intoaquatic ecosystems in the United States (Moen 1999).

In my assessment, this ballast water should beheated to 63�C before it is released. This should kill allor most microbe organisms (Rigby and others 1999).The use of chemicals for ballast water has many draw-backs, including efficacy and pollution. This is espe-cially so when the polluted ballast water is released.

Suggestions are made about taxing and finingshippers and others when they introduce an exoticspecies that becomes a pest. This approach suggeststhat approximately a 1% risk for invasive species gain-ing entrance into the United States is a satisfactory risk.Although it is impossible to prevent all introducedinvasive species, no management policy should beadopted that permits approximately 1% invaders.Introduced species, like the zebra mussel, Asian clam,and West Nile virus, cause more than $5 billion indamages and control costs annually for an unknownnumber of years. Thus, any management scheme thatpermits 1% introduced species is not an acceptablerisk.

The Nonindigenous Aquatic Species Threat

With increasing numbers of aquatic exotic species inthe New York State Canal and Hudson River systemsand the Great Lakes Basin, many species are harmfuland it does not take very many to inflict significantdamage to these environmentally sensitive aquaticecosystems. A suite of ecological factors might causeparticular nonindigenous species to become abundantand persistent. These include the lack of controllingnatural enemies, the ability of an alien parasite toswitch to a new host, an ability to be an effective

$2000 (UMN 2002) and it is estimated that about 1000 ha are cleared

of weeds each year associated withrecreational boating.vZebra and quagga mussels interfere with some aspects of recreational

boating, such as buildup of mussels on the hulls and motors of the

boats. Increased drag and cleaning of the mussels is estimated to cost

$500,000 per year.wNuisance and control costs of the Asian clam and mosquitoes are

estimated to cost recreational boating $500,000 per year. The Asian

clam causes about $1 billion in damages and control costs each year in

the United States (Pimentel and others 2000).

xNuisance mosquito and other biting insect control costs were esti-

mated to be $1 million per year.yBird populations are being infected by the West Nile virus and re-

duced in number (Weiss 2002). The negative impact on bird watching

is estimated to be $2 million per year.zA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $1 million per year

based on 65,000 people exposed and $15 per person for spraying.

Aquatic Nuisance Species Assessment (Northeast) 697

Table 5. Environmental and economic impacts (damage and control costs) of biological invaders in the GreatLakes Basin in millions of dollars

Functional group

Stakeholdergroup Fish Algae

Aquaticplants Mussels

Otherinvertebrates Birds

Pathogens andparasites Total

Landowner, agriculture 1a 2b 3Public health 610c 610Tourism 4d 0.5e 10f 1g 2h 17.5Electric industry 480i 10j 490Commercial fishing 2250k 10l 13m 5n 1o 2279Sport fishing 2250p 10q 5r 3s 5t 2273Boating 4u 0.5v 0.5w 5Transport 1x 1y 1z 3Bird/wildlife watchers 2aa 2aa 1bb 5Total 4500 29 500 31.5 4 621 5685.5

aDamages to agriculture and control costs associated with starlings

and pigeons (Pimentel and others 2000).bWest Nile virus infections and deaths in horses in the Great Lakes

Basin; estimate based on the fact that New Jersey reported $6 million

in losses in horses occur each year (AHC 2003).cAn estimated 33.5 million people in the Great Lakes Basin (EPA

1996) and an estimated 2 million are exposed to mosquitoes trans-

mitting West Nile virus. The cost of spraying for adult mosquito

control is reported to be $14.40 per person (Hansen 2003), thus

about $30 million in costs. In addition, there were 2067 cases of West

Nile virus infections, plus 155 deaths in the 7 states in the Great Lakes

Basin (CDC 2003). Assuming $3.7 million per death as suggested by

the EPA (Weinberg 2003) plus hospitalizations, outpatients, and lost

work, the total cost of this human health problem is $610 million per

year (Pimentel in press).dWeeds interfere with swimming and the esthetics of the environ-

ment. The cost of either mechanical or chemical weed control per

hectare is approximately $2000 (NYSCC 2002; UMN 2002; Bouchard

2003; SePRO 2003) and it is estimated that about 2000 ha are cleared

of weeds each year.eZebra and quagga mussels cover the bottom of some beaches and

cause cuts on swimmers’ feet (WNR 2001). The estimated impact is

$500,000 per year.fMosquito control costs about $14.40 per person for control (Hansen

2003). It is estimated that about 2 million tourists visit the Great Lakes

Basin each year and �700,000 people visit tourist locations requiring

mosquito control operations.gBird populations are being infected by the West Nile virus and re-

duced in number (Weiss 2002). The negative impact on tourism is

estimated to be $1 million per year.hSome spraying is carried out for the protection of tourists from the

West Nile virus and this is estimated to be about $2 million per year.

See footnote f.iZebra and quagga mussel damage and control costs to electric power

plants and public water supply plants are an estimated $480 million

per year in the Great Lakes Basin. This is based on the estimate that

mussels cause $500 million in economic impacts per year (Malta 2003;

World Press Review 2003). However, another higher estimate is $3

billion per year (Licking 1999) in damages and control costs in the

Great Lakes. Zebra and quagga mussels cause damages and control

costs that cost the United States as a whole an estimated $1 billion per

year (Pimentel and others 2004; CRC Reef Research 2003).jAsian clam damages and control in the United States are estimated to

cost about $1 billion per year (Pimentel and others 2000), Use of

water by power plants in the Great Lakes Basin requires an estimated

$10 million per year to control the Asian clam.

kInvasive species in the Great Lakes Basin are causing an estimated

$2250 million in damages to commercial fisheries each year (Standing

Committee on Fisheries and Oceans 2003). This is based on the im-

pacts of invasive species of fish and other organisms in the Great

Lakes that is estimated to be about $2.5 billion in damages and

control costs per year (Sea Grant 2002a).lWeeds interfere with some commercial fishing operations. The cost

of either mechanical or chemical weed control per hectare is �$2000

(NYSCC 2002; UMN 2002; Bouchard 2003; SePRO 2003) and it is

estimated that about 5000 ha are cleared of weeds each year.mZebra and quagga mussels interfere with some aspects of commer-

cial fishing, such as buildup of mussels on the hulls and motors of

boats. Increased drag and cleaning of the mussels is estimated to cost

$13 million per year based on a 0.3% impact on the commercial

fishing industry.nNuisance and control costs of the Asian clam are estimated to cost

the fishing industry an estimated $5 million per year based on a 0.5%

impact on the commercial fishing industry.oA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $1 million per year

based on 65,000 people exposed and $15 per person for spraying.pInvasive species in the Great Lakes Basin are causing an estimated

$2250 million in damages to sports fisheries each year (Standing

Committee on Fisheries and Oceans 2003). This is based on the im-

pact of invasive species of fish and other organisms in the Great Lakes

that is estimated to be about $2.5 billion in damages and control costs

per year to sports fisheries (Sea Grant 2002a).qWeeds interfere with some commercial shipping. The cost of either

mechanical or chemical weed control per hectare is �$2000 (NYSCC,

2002; UMN 2002; Bouchard 2003; SePRQ 2003) and it is estimated

that about 5000 ha are cleared of weeds each year associated with

sports fishing.rZebra and quagga mussels interfere with some aspects of shipping,

such as buildup of mussels on the hulls and motors of boats. In-

creased drag and cleaning of the mussels is estimated to cost $5

million per year based on a 0.25% impact on the sport fishing

industry.sNuisance and control costs of the Asian clam and mosquitoes are

estimated to cost sports fishing $3 million per year based on 0.3%

impact on the sport fishing industry.tA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $5 million per year

based on 350,000 people exposed and $15 per person for spraying.uWeeds interfere with some boating operations. The cost of either

mechanical or chemical weed control per hectare is �$2000 (NYSCC

2002; UMN 2002; Bouchard 2003; SePRO 2003) and it is estimated

698 D. Pimentel

predator in the new ecosystem, the availability of dis-turbed habitats that provide a highly susceptible eco-system for alien species, and the high adaptability tonovel conditions (Pimentel 2002).

A total of 154 aquatic alien species have invaded theNew York State Canal and Hudson River systems and atotal of 162 aquatic alien species have invaded theGreat Lakes Basin. In New York State, the nonindige-nous species are causing an estimated $500 million ineconomic losses each year. The economic and envi-ronmental situation in the Great Lakes Basin is farmore serious from nonindigenous species, with lossesestimated to be about $5.7 billion dollars per year.Commercial and sport fishing suffer the most from thebiological invasions, with about $400 million in lossesreported for the New York State Canal and HudsonRiver systems and $4.5 billion in losses reported for theGreat Lakes Basin (Tables 4 and 5).

Other invasive alien species causing major economicand environmental damages in the New York StateCanal and Hudson River systems include mussels($12.5 million per year), other invertebrates ($25.5million per year), and pathogens and parasites ($47.5million per year) (Table 4). Other alien invasive spe-cies in the Great Lakes Basin causing economic andenvironmental damages include mussels ($500 millionper year), other invertebrates ($31.5 million per year),and pathogens and parasites ($621 million per year)(Table 5).

Although a specific total is reported for economicdamages, the associated control costs resulting fromthe invasive nonindigenous aquatic species in theseaquatic ecosystems are not available.

The true challenge for the public lies not in deter-mining the precise costs of the impacts of aquaticexotic species but in preventing further damage to theNew York State Canal and Hudson River and the GreatLakes Basin ecosystems. Sound prevention policies

need to take into account the means through whichnonindigenous aquatic species gain access to and be-come established in the United States. Because themodes of invasion vary widely from intentional intro-ductions to accidental introductions by various means,like ballast water and organisms attached to the hulls ofboats, a variety of preventive strategies are needed. Forexample, public and inspector education, sanitation,and effective screening and searches at airports, sea-ports, and other ports of entry will help reduce thechances that biological invaders will become estab-lished.

Prevention is the only practical means of dealingwith the alien invasive species problem in the New YorkState Canal and Hudson River and the Great LakesBasin ecosystems, because exterminating an exoticspecies once it is established is nearly impossible. Oncethe invading species is established, it can be assumedthat it is here to stay. Based on my estimates, approxi-mately $5 million per year, or 10% of the currentdamage and control costs, would be needed for aprevention program in the New York State Canal andHudson River systems. This 10% is a relatively smallinvestment to prevent adding to the more than $500million losses due to invasive species each year (Ta-ble 4).

A greater investment is needed in the biologicalcontrol of some of the invasive species. For example,the results of the introduction of biological agents forcontrol of purple loosestrife appear encouraging(Blossey and others 2001). The objective in biologicalcontrol is to reduce the invading species to a level thatit is no longer causing economic and environmentaldamage to the natural ecosystem.

The alien species problem is gaining the attentionof policy-makers. President Clinton created the In-teragency Invasive Species Council to plan and createlaws and regulations that would help reduce the

that about 2000 ha are cleared of weeds each year associated with

recreational boating.vZebra and quagga mussels interfere with some aspects of recreational

boating, such as buildup of mussels on the hulls and motors of boats.

Increased drag and cleaning of the mussels is estimated to cost

$500,000 per year, The cost of treating medium-sized boats with

antifouling paints ranges from $340 to $900 per boat. A one-time

epoxy primer for new boats adds $1000 to the cost (DCLW 2003).wNuisance and control costs of the Asian clam and mosquitoes are

estimated to cost recreational boating an estimated $500,000 per year

based on an impact of 0.01% on recreational boating.xAquatic weeds interfere with some commercial shipping. The cost of

either mechanical or chemical weed control per hectare is �$2000

(NYSCC 2002; UMN 2002; Bouchard 2003; SePRQ 2003) and it is

estimated that about 500 ha are cleared of weeds each year associated

with shipping.

yZebra and quagga mussels interfere with some aspects of shipping,

such as buildup of mussels on the hull of the ships. Increased drag

and cleaning of the mussels is estimated to cost $1 million per year

based on a 0.04% impact on the transport industry.zNuisance mosquito and other biting insect control costs were esti-

mated to be $1 million per year based on 65,000 people exposed and

$15 per person for spraying.aaBird populations are being infected by the West Nile virus and re-

duced in number (Weiss 2002). The negative impact on bird watching

is estimated to be $2 million per year.bbA limited amount of spraying for West Nile virus and nuisance

mosquitoes is done. This is estimated to be about $1 million per year

based on 65,000 people exposed and $15 per person for spraying.

Aquatic Nuisance Species Assessment (Northeast) 699

chances of new biological invaders invading the UnitedStates. The US Congress has proposed allocating morefunds to investigate the problem and develop new waysto prevent and develop biological controls for some ofthe alien invasive species into the United States.

AcknowledgmentsThis investigation was kindly supported by an award

from the Fish and Wildlife Service, Number 50181M499. I thank Michael Goehle of the Fish and WildlifeService, David Lodge of the University of Notre Dame,and Anne Wilson and Marcia Pimentel of CornellUniversity for their valuable comments and suggestionsthat helped strengthen this report.

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