36 Fisheries | www.fisheries.org | vol 30 no 7

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mIntroduction

Wilcove et al. (1992) reported a dou-bling of the extinction rate for NorthAmerican fishes over the course of thetwentieth century. The primary class offish, Osteichthyes, has a higher percent-age of species listed as threatened orendangered pursuant to the EndangeredSpecies Act (ESA) than all other classes of animals(FWS 2004). There are 114 U.S. fish species federallylisted as threatened or endangered, which is nearly14% of the approximately 822 native fish species inthe United States (Stein and Flack 1997). The West,Southwest, and Southeast are the regions with themost listed fish species and the highest percentage ofnative freshwater fish species that are listed (Figure 1).

While the decline of U.S. fish species is clear, addi-tional scrutiny of the reasons is necessary forascertaining policy implications and developing effec-tive solutions. Fortunately for these purposes, the U.S.Fish and Wildlife Service and the National MarineFisheries Service are required to asses the reasons for aspecies’ imperilment when determining whether to listthe species pursuant to the ESA. More specifically, theagencies determine whether a species is threatened orendangered based upon the following factors: (A) thepresent or threatened destruction, modification, or cur-tailment of its habitat or range; (B) overutilization forcommercial, recreational, scientific, or educational pur-poses; (C) disease or predation; (D) the inadequacy ofexisting regulatory mechanisms; or (E) other natural ormanmade factors affecting its continued existence (16U.S.C. 1533). For each determination, these factors arepresented in the Federal Register. Therefore, the Federal

Register has been used for analyzing thecauses of species endangerment in theaggregate (Czech and Krausman 1997;Wilcove et al. 1998).

Causes of FishEndangerment

We updated the endangered speciesdatabase developed by Czech and

Krausman (1997) with data from the Federal Registerto include U.S. fish species listed up to April 2005.There are 18 basic categories of species endangermentcauses (Table 1). We did not include habitat fragmenta-tion, which we think is more appropriately categorizedas an effect of the other causes.

The cause of endangerment imperiling the mostfish species in the United States is surface water diver-sions, which threaten 84 fish species or 74% of allthreatened and endangered fish species (Table 1).Invasive species and pollution are the next greatestthreats to fish species in the United States. Both areimplicated in the decline of nearly 50% of federally-listed fish species. Agriculture imperils about 41% oflisted fish species. After agriculture, the remainingcauses affect ESA-listed fish species less frequently(Table 1).

Rarely are species endangered by only 1 of the 18causes. The average number of causes endangering afish species is 3.5, and fish species have been endan-gered by as many as 8 of the 18 causes.

If one considers a species independently of the oth-ers, microeconomic implications pertaining to localizedeconomic activities (such as a particular water diversion,road system, or timber sale) can be identified for eachspecies. For the purposes of the Economic Growth

Causes of Fish Endangerment in theUnited States, or the Structure of theAmerican Economy

Kelly Miller ReedBrian CzechKelly Miller Reed is a grants manager at the InternationalAssociation of Fish andWildlife Agencies,Washington, D.C. andcan be contacted atkreed@iafwa.org. BrianCzech is at VirginiaPolytechnic Instituteand State University,Alexandria, VA.

Figure 1. Number of U.S.fish species listed pursuantto the Endangered SpeciesAct by state and region.Parentheses contain thepercentages of state'snative freshwater fishesthat are listed. A listedspecies can occur in morethan one state so the statesubtotals do not total the114 listed U.S. species anddo not total the numberof unique species in eachregion. Warren and Burr(1994) provided data fornative freshwater fishspecies found in eachstate.

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Forum, however, it is more important to focus on the causes ofendangerment in the aggregate and to consider the macroeconomicimplications.

Economic Infrastructure and SectorsAs Adam Smith described in Wealth of Nations, agriculture is the

foundational sector of the economy. Agricultural surplus frees thehands for the division of labor, bringing into existence the manufac-turing sectors (Smith 1776).

Surface water diversions (most notably dams), along with roadconstruction and maintenance, represent the infrastructure of theAmerican economy. For example, dams are used for generating elec-tricity, reservoirs are integral to agricultural production (especially inthe West), and roads are necessary for the operation of virtually alleconomic sectors.

Aquifer depletion and wetlands destruction are typically the resultof agricultural, industrial, and municipal activities. Mining, grazing,logging, and direct harvest (of threatened and endangered species)represent the extractive sectors.

Urbanization represents the proliferation of the labor force, lightmanufacturing, and service sectors. Outdoor recreation and tourismdevelopment, interacting as one of the service sectors, have such adirect impact on fish species that they warrant a separate category.“Industrial activities” represent the heavier manufacturing and othersectors not typically located in the urban core.

All economic sectors entail the reallocation of natural capital (suchas soils, water, and minerals) from the “economy of nature” with itsnonhuman species (including fish) to the human economy (Trauger etal. 2003). (The reallocation of natural capital is captured in the logofor this special series, with fish being liquidated as higher volumes ofmoney are generated.) This reallocation of natural capital illustratesthe ecological principle of “competitive exclusion” (Pianka 1974), withthe human economy growing at the competitive exclusion of fish andother nonhuman species in the aggregate.

Economic Byproduct Pollution, the second most prominent cause of fish endangerment,

is a byproduct of economic production and consumption across sec-tors. Ceteris paribus, more economic production means morepollution. Cleaner production processes may be developed, but eco-nomic growth entails increasing production using current levels oftechnology while cleaner technologies come online (Czech 2003).

Also, new technologies often cause pollution that is not fully under-stood for its negative effects until long after the sectors employing ithave proliferated (Booth 2004).

Trade and Commerce

The spread of invasive species is a function of international tradeand interstate commerce. As Ericson (2005) pointed out in a recentFisheries article, “As the rate of non-indigenous, potentially invasivespecies introduction accelerates, trade itself begins to look more andmore like a sort of ‘metavector’ comprising numerous, individual, yetassociated, vectors.” Aquatic species invasions are particularly linkedto international trade due to the prominence of oceanic and riverinetransport of capital and consumer goods. Especially since the nine-teenth century writings of the great classical economist, DavidRicardo, international trade has been cited as a particularly effectivemeans for the economic growth of nations (Ricardo 1817).

Incidental and Exacerbated Effects ofEconomic Growth

A few causes of species endangerment (i.e., genetic problems, dis-ease, and native species interactions) are naturally occurring ecologicaland evolutionary phenomena. However, these causes typically do notthreaten the existence of a species until their effects are exacerbatedby other causes of endangerment with more direct links to the econ-omy (Czech et al. 2000). For example, inbreeding depression (agenetic problem) may begin to imperil a species once its populationhas been decimated by the more prominent, economic causes ofendangerment. This helps explain why no fish species are federallylisted for entirely natural reasons.

The causes of endangerment with the least connection to eco-nomic growth tend also to be least problematic. For example,modified fire regimes do not constitute an economic sector, infrastruc-ture, or byproduct. Modified fire regimes are only implicated in theendangerment of three species, and even they may be described asan incidental function of economic growth because they typicallyresult from the habitat conversions and management associated witheconomic sectors and infrastructure.

Ranking Cause of Endangerment # of Species % of Listed Fish1 Surface water diversions 84 73.0%2 Invasive Species 56 48.7%2 Pollution 56 48.7%3 Agriculture 47 40.9%4 Aquifer Depletion and Wetland Conversion 27 23.5%5 Urbanization 26 22.6%6 Mining, Oil, Gas Activities 24 20.9%7 Grazing, Other Ranching Activities 16 13.9%8 Logging 14 12.2%8 Roads 14 12.2%9 Genetic Problems 13 11.3%10 Recreation and Tourism 9 7.8%11 Industrial, Military Activities 6 5.2%12 Native Species Interactions 5 4.3%13 Harvest 4 3.5%14 Modified Fire Regimes, Silviculture 3 2.6%15 Vandalism 1 0.9%16 Disease 0 0.0%

Table 1. Causes of fishspecies endangerment inthe United States. Thereare 18 causes, with twopairs tied in frequency.Habitat fragmentation isnot included because it isan effect of other causes.

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ConclusionThe empirical evidence

presented here supplementsthe theoretical constructs ofa fundamental conflictbetween economic growthand biodiversity conserva-tion (Trauger et al. 2003).Correlation does not provecausality, but our analysisindicates that the strongcorrelation between fishspecies listings and GDP isno coincidence (Figure 2).As with the conservation ofother nonhuman species,fish conservation appears torequire either: (1) the estab-lishment of a steady stateeconomy with a stabilizedor mildly fluctuating productof population times percapita consumption, or, (2)a shrinking human econ-omy. We think there is anoptimum size of theAmerican economy, andthat this size is determined in part by how many fish and other non-human species remain. In other words, the optimum size entails anequilibrium between the American economy and the economy ofnature.

In a democracy, the optimum size would be determined neither bythe business community nor by the natural resources professions, butby the collective preferences of citizens. For example, presumably fewcitizens would prefer a reduction in economic activity to a level farbelow the current level, even if that new level made it possible toretain all remaining fish species. On the other hand, presumably fewcitizens would prefer economic growth to the point that 90% of fishspecies were eliminated from the wild, even if that new level ofgrowth was portrayed as “economic progress” as indicated by GDP.The optimum steady state economy would lie somewhere inbetween, with market and non-market factors of welfare considered.

Economists and ecologists should not expect to develop anauthoritative estimate of the optimum size for the U.S. economy,although each should contribute to a fuller understanding of marketand non-market factors of welfare. In a functional democracy,American society may come to settle upon a sustainable, satisfactory,steady state economy. This evolutionary process will entail enlightenedconsumer preferences, political participation, and prudent public pol-icy. For this to happen, citizens will need to understand the conflictbetween economic growth and fish conservation, as well as thebroader conflict between economic growth and environmental pro-tection. We believe the American Fisheries Society, along with sistersocieties such as the Wildlife Society, Society for Conservation Biology,and Ecological Society of America, can play a crucial role in the devel-opment of that understanding.

ReferencesBEA (U.S. Bureau of Economic Analysis).

2005. Current-dollar and “real” grossdomestic product.www.bea.gov/bea/dn/home/gdp.htm.(Visited 10 April 2005.)

Booth, D. E. 2004. Hooked on growth:economic addictions and the environment.Roman and Littlefield, Lanham, Maryland.

Czech, B. 2003. Technological progress andbiodiversity conservation: A dollar spent adollar burned. Conservation Biology17(5):1455-1457.

Czech, B., and P.R. Krausman. 1997.Distribution and causation of speciesendangerment in the United States.Science 277:1116-1117.

Czech, B., P. R. Krausman, and P. K. Devers.2000. Economic associations of species

endangerment causes in the United States.BioScience 50(7):593-601.

Ericson, J. 2005. The economic roots ofaquatic species invasions. Fisheries30(5):30-33.

FWS (U.S. Fish and Wildlife Service).2004. Threatened and endangered speciessystem. http://ecos.fws.gov/tess_public/TESSWebpage.

Pianka, E. R. 1974. Evolutionary ecology.Harper and Row, New York.

Ricardo, D. 1817. The principles of politicaleconomy and taxation. J. M. Dent 1937edition, London, United Kingdom.

Smith, A. 1776. An inquiry into the natureand causes of the wealth of nations.Clarendon Press 1976 edition, Oxford,United Kingdom.

Stein, B. A., and S. R. Flack. 1997. 1997species report card: the state of U.S. plants

and animals. The Nature Conservancy,Arlington, Virginia.

Trauger, D. L., B. Czech, J. D. Erickson, P.R. Garrettson, B. J. Kernohan, and C. A.Miller. 2003. The relationship of economicgrowth to wildlife conservation. WildlifeSociety Technical Review 03-1. TheWildlife Society, Bethesda, Maryland.

Wilcove, D.S., M. Bean, and P. Lee. 1992.Fisheries management and biologicaldiversity: problems and opportunities. In:Transactions of the 57th North AmericanWildlife and Natural ResourcesConference. Wildlife ManagementInstitute, Washington, DC.

Wilcove D. S, D. Rothstein, J. Dubow, A.Phillips, and E. Losos. 1998. Quantifyingthreats to endangered species in the UnitedStates. Bioscience 48(8):607-616.

Figure 2. Correlation of fish species listed pursuant to the Endangered Species Act (ESA) and gross domesticproduct (GDP) in the U.S; (FWS 2004, BEA 2005). R2 = 0.94.