Preliminary Results July, 2008

Invasive Species in the Great Lakes: Costing Us Our Future

Annual Losses to Great Lakes Region by Ship-borne 

Invasive Species at least $200 Million

Preliminary research suggests that the annual cost to the Great Lakes region from invasive 

species introduced by shipping may be upwards of $200 million dollars a year because 

invasions limit the ability of the natural ecosystem to support fisheries, raw water uses, and 

wildlife watching. 

Raw water users

$27,000,000

Wildlife Watching

$47,659,000

Sport Fishing

$123,553,000

Commercial Fishing

$2,117,000

Estimate of loss consumer surplus:

$200,329,000

Preliminarily results, based on a set of conservative parameters, show that in 2006, 

ship-borne invasive species may have cost upwards of $200 million in lost economic 

benefits to consumers by reducing sport and commercial fisheries, reducing wildlife 

watching, and increasing the operating costs for raw water users, compared to a 

scenario of no ship-borne invasions. Dollar values rise for less conservative parameter 

combinations and fall when parameter combinations are more stringent. A fuller 

economic analysis will incorporate a complete range of values and interactions among 

these and other sectors within the Great Lakes economy.

The establishment of invasive species can affect the services 

provided by the Great Lakes ecosystem. This study examined 

how four kinds of ecosystem services were impacted by invasive 

species from ocean-going vessels arriving since the St. Lawrence 

Seaway opened in 1959. It examined only U.S. data, but similar impacts are likely experienced in Canada. These results are 

preliminary and unpublished, and represent the low end of the 

range of estimated impacts for reasonable parameter combinations. A more complete economic analysis is underway. 

Key Findings

The data reflect findings for 2006. Considering that new invasive 

species are being discovered every year, and species already present are spreading, it is likely that the losses experienced in 2006 

will increase in following years.

Results from the study indicate that reductions in Great 

Lakes commercial fishery landings attributable to ship-borne 

invasive species range from 13% to 33%, depending on lake.

Participation in recreational fishing on the Great Lakes was 

estimated to be 11%-35% less than it would have been without ballast-introduced invasive species, depending on lake.

Effects of ship-borne invasions on participation in wildlife 

watching for the entire 8-state region (this analysis could not 

be limited to the Great Lakes proper) were lower, about 1%.

There was a wide range of costs to raw water users (facilities 

like power plants, industries, or municipal suppliers who require fresh water from the lakes), from $30,000 to $118,000 

per year, depending on facility type. The facilities using the 

most water were impacted most strongly.

Impacts varied according to ecosystem service – monetary 

losses to sport fishing were greatest, followed by wildlife 

watching, raw water supply services, and then commercial 

fishing.

Methodology

Most studies focus on the impact of one or two high-profile 

invasive species. Considering, too, that traditional ecological 

research is not done at a large enough spatial scale to address 

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economic impacts, few inferences about economic impacts could 

be derived from the scientific literature.

 To address this gap, Structured Expert Judgment was used 

to assess the uncertainty around the ecological impact from 

ship-borne invasive species. The lost economic benefit to consumers was then estimated from the ecological changes predicted by experts. When scientific research is uncertain or sparse, 

this methodology is commonly used to provide policy guidance.. 

 Experts from a variety of fields including fishery biologists, 

environmental economists, and Great Lakes food web ecologists 

were asked about a suite of ecosystem services that ship-borne 

invasive species could affect. These included commercial fish 

landings, recreational fishing effort, raw water usage, and nonconsumptive uses like wildlife watching. These four ecosystem 

services were selected because they are important to the regional 

economy, reliable historical data for each is available, and invasive species are known to or could plausibly impact each one.
Preliminary Results July, 2008

David Lodge

University of Notre Dame

574-631-6094

dlodge@nd.udu

David Finnoff

University of Wyoming

307-766-5773

finnoff@uwyo.edu

Commercial Fishing

Sport Fishing

13%

LAKE SUPERIOR

18%

LAKE ERIE

23%

LAKE HURON

33%

LAKE ONTARIO

21%

LAKE MICHIGAN

35%

LAKE SUPERIOR

15%

LAKE ERIE

18%

LAKE HURON

13%

LAKE ONTARIO

11%

LAKE MICHIGAN

Wildlife Watching

0.8%

ALL GREAT LAKES

What is an ‘Ecosystem Service’?

Ecosystem services are the benefits that the natural environment 

offers to the communities and economy of the Great Lakes. 

While these can be difficult to quantify, this research looked at 

three areas in order to estimate the value of some services the 

Great Lakes provide.

Sport and Commercial Fisheries

Fish harvests and time spent sport fishing provide benefits, but 

when invasive species decrease harvests or lower the quality of 

the recreational opportunities, these benefits may be diminished. 

This is because there are fewer fish caught and taken to market 

and what people are willing to pay to sport fish may also decline.

Wildlife Watching

Admiring wildlife and the experience of wildlife watching provide benefits, but when invasive species decrease environmental 

quality and the quality of the experience, these benefits may 

decline as people may be willing to pay less to watch wildlife.

Raw Water Uses

Municipalities, power plants, and some industries rely on access 

to water to function. Invasive species clog and damage intake 

pipes, increasing maintenance and operational costs.

How ecosystem services were measured

Valuing ecosystem services

Economic valuation of ecosystem services is a challenging task. 

To generate the preliminary dollar values presented here, simple 

market models of supply and demand for commercial fishing, 

recreational fishing and wildlife watching were used. Additional 

operating costs in dollar units were available for raw water use. 

If invaders affect the provisioning of ecosystem services, they 

can result in lost consumer and producer surplus (which are the 

opportunity costs to society). Consumer surplus is the benefit to 

consumers of a market outcome and accrue whenever consumers pay less than the maximum amount they would be willing 

to pay for that unit of a good. Producer surplus is the benefit 

to producers from the outcome, and accrue whenever producers 

are paid more for a unit of a good than the minimum that they 

would be willingly to accept for that unit. 

 To provide an indication of the lost benefits to society of 

ship-born invasions, changes in consumer surplus were estimated for commercial fishing, recreational fishing, and wildlife 

watching. The calculations were made using the median results 

of the expert elicitation and a range of parameter combinations; 

the results reported here for a conservative suite of parameters. 

For effects on raw water users, additional per facility operating costs arising from biofouling by non-native species were 

elicited from experts. We then multiplied median per facility 

estimates by the number of facilities in the region. All the consumer surplus measures provided here were generated without 

accounting for multi-market, income, and adaptation effects. 

Incorporating these effects in future analyses will likely generate 

economic impact estimates different from those presented here.

For more information

SizeS of The Economic Sectors Studied

The economic sectors evaluated in this study differ in current 

size. The estimates below do not include Canada.

Sector Size

Commercial fishing $15 million market value of fish landed from the 

Great Lakes in 2006.1

Recreational fishing $1.5 billion in angler expenditures on Great 

Lakes fishing2

Wildlife watching $9.3 billion in participant expenditures for the 

eight Great Lakes states.3

Raw water users 826 facilities, including 13 nuclear power 

plants.4

1 The United States Geological Survey Great Lakes Science Center

2 United States Fish and Wildlife Service, The 2006 National Survey of Fishing, 

Hunting, and Wildlife-Associated Recreation

3 United States Fish and Wildlife Service (2006)

4 Deng (1996); O’Neill (1996); Northeast Midwest Institute

Median reductions estimated by Structured Expert Judgment by lake. Impacts to commercial fishing is based on reductions in weight of fish harvest from the Great Lakes. 

Impacts to sport fishing is based on reductions in number of person-days spent sport 

fishing on the Lake. Impacts to wildlife watching is based on reductions in person-days 

spent wildlife watching.

To produce the dollar estimates presented in the pie-graph on page 1, these 

percent impacts were converted into estimates of lost consumer surplus in dollars, using 

simple economic models with conservative assumptions.

Estimated Reductions to Fisheries and 

Wildlife watching