Burkhead Fish Extinctions
Burkhead Fish Extinctions
Burkhead Fish Extinctions
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Articles
Noel M. Burkhead
Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the
present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three
distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From
the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean=
7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern
extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for
freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86
species by 2050.
BioScience 62: 798808. ISSN 0006-3568, electronic ISSN 1525-3244. 2012 by American Institute of Biological Sciences. All rights reserved. Request
permission to photocopy or reproduce article content at the University of California Presss Rights and Permissions Web site at www.ucpressjournals.com/
reprintinfo.asp. doi:10.1525/bio.2012.62.9.5
North American freshwater fishes: A brief synopsis and the filling of numerous basins gouged by the giant
North America is geographically defined as Canada, the ice sheets (e.g., the Great Lakes; Hocutt and Wiley 1986).
United States, and Mexico, including the coastal islands off The evolution and biogeography of the North American
Canada and Alaska but excluding Hawaii and the southern fish fauna is intimately linked to transitional changes to
Mexican states of Quintana Roo and Campeche (Jelks etal. landforms and their influences on continental watercourses
2008). The diversity of fishes is equivalent to that of all other over time (Mayden 1988, Smith GR etal. 2002). Generally,
vertebrate groups combined (Nelson 2006); therefore, the species richness per drainage (or ecoregion) increases from
number of descriptions of fishes new to science exceeds that Canada southward, but over two-thirds of species richness
of descriptions of new tetrapods each year. At the close of occurs east of the Great Continental Divide, especially in
2010, the cutoff point for this study, 31,769 valid fish species the Interior and Appalachian Highlands (Hocutt and Wiley
had been described worldwide (William N. Eschmeyer, 1986, Mayden 1992). Fishes in the western United States and
California Academy of Sciences [retired], personal com- Mexico exhibit relatively lower species richness per drainage
munication, 28 August 2011). About 43% of the worlds unit but generally have higher endemism and dispropor-
fishes are freshwater or diadromous species (Nelson 2006). tionate numbers of extinct species (Minckley and Douglas
Comparatively, the freshwater fish diversity of North America 1991, Burr and Mayden 1992).
is less than those of Africa (about 2945 species), Asia (3533),
and South America (4035), but higher than those of Europe Rates of faunal documentation and evidence of
(330), Russia (206), and Oceania (260) (Lvque etal. 2008). extinction
North America has the most diverse nontropical freshwater Our knowledge of North American fishes is facilitated by
fish fauna in the world (Lundberg etal. 2000). At the end of a long tradition of faunal study and public access to most
2010, the freshwater fish fauna of North America consisted river and lake systems. From 1758 to 2010, the average
of 53 families, 214 genera, and 1213 species, or about 8.9% rate of fish descriptions for North America was 4.8 species
of the Earths freshwater fish diversity (Nelson etal. 2004). described per year, but as is evident in figure1a, the rates
Continental fishes primarily consist of obligate freshwater varied over time and logically increased as more biologists
species, diadromous fishes (species in which part of their life studied the fauna. From 1970 through 2010, species docu-
cycle occurs in the marine realm), and marine fishes that mentation averaged 6.7 species described per year, which is
occasionally or regularly enter freshwater during their lives. considered the modern rate of faunal discovery and docu-
The tally through 2010 is based on independent counts of mentation (figure 1a). The discovery and description of
species described after 2004, aided by comments from Larry North American freshwater fishes continues unabated, and
Page (University of Florida Museum of Natural History, unlike birds (see Pimm and colleagues [2006] figure 1),
personal communication, 14 October 2010). there is no evidence of an asymptote in the rates of species
descriptions.
Patterns of species richness Modern extinctions of North American fishes were first
Until recently, most species of the modern North American observed at the dawn of the twentieth century, and the trend
fish fauna were considered derived from the mid-Miocene continues (figure 1b). The exact year of extinction can be
to the late Pleistocene, or about 151.5 million years ago difficult to document (Harrison and Stiassny 1999) because
(mya) or less (Mayden 1988, Strange and Burr 1997, Smith of the inherent difficulty of observing an organism when
GR et al. 2002). However, cross-calibration of molecular- theprobability of its detection approaches zero. Among the
clock and fossil data (chronograms) has significantly revised first fishes observed to be declining (and later to become
the concepts of lineage ages in fishes. For example, half of extinct) were commercially important Great Lakes fishes for
the sunfish familys (Centrarchidae) lineages significantly which harvest data were kept (McCrimmon 2002). Included
predate the Pleistocene, and the least-derived taxonthe in that group is the first fish population to disappear from
mud sunfish (Acantharchus pomotis)emerged by the early North America, the Lake Ontario population of the highly
Oligocene, 33.7mya (Near etal. 2005). The mean age esti- valued Atlantic salmon (Salmo salar). The year of expira-
mates for species lineages in the diverse family Percidae have tion for six narrow endemics is exactly known because the
been pushed back to the Oligocene, from 30.7 to 34.8mya desiccation of their habitats (four springs and one caldera)
(Near et al. 2011). These studies suggest that many North was observed. These species included five desert pupfishes
American fishes are likely to be far older than was previously (Cyprinodon spp.; Contreras-Balderas and Lozano-Vilano
recognized. 1996) and the last known fish to go extinct in North America,
There is, however, clear evidence for the derivation of spe- the Alberca silverside (Chirostoma bartoni), which vanished
cies from the late Pleistocene (Near and Benard 2004, Near when the Alberca caldera temporarily dried in August
etal. 2005) to the last 10,000years for species that evolved 2006 (Edmundo Daz Pardo, Universidad Autonoma de
after the glaciers retreated (e.g., Hatfield 2001, Taylor etal. Queretaro, personal communication, 13 September 2007).
2006). The end of the Pleistocene was demarked by dramatic In many cases, extinction was recognized only in hindsight,
changes: subsidence of glaciers, rising sea levels, severing and the last year of observation was used to estimate the
of lateral connections between some coastal drainages, extinction year (Miller etal. 1989).
Table 1. Continued
Estimated year
Family Scientific name Common name of extinction
Note: The common names of undescribed taxa are in quotation marks. Abbreviations: sp., species; ssp., subspecies; pop, extirpated population.
a
35 extinct fishes (Miller etal. 1989).
b
25 taxa added to the list by Jelks and colleagues (2008).
c
32 taxa for which the last year of observation is the same as the estimated year of extinction.
near-future extinction rates out to 2050 in the continents The patterns of decadal extinctions in North America
freshwater fish fauna. roughly paralleled those on other continents, but the num-
ber of extinctions across decades was significantly higher in
Current rates of extinction North America than those in all other continents combined
Rates of extinction can be estimated indirectly using (figure3). Of the estimated 83 extinct fish species and sub-
speciesarea relationships (May etal. 1995), from models species worldwide (IUCN 2011), North America accounts
(Ricciardi and Rasmussen 1999), or directly when extinct for 57, Eurasia 19, Africa and Madagascar 5, South America
taxa and associated data are known. All extinct or extir- 1, and Oceania 1. Some of these discrepancies clearly relate
pated fishes treated herein represent modern losses as to the numbers of ichthyologists and the history of fau-
opposed to extinctions in the geological past (table 1). nal investigation in different regions of the world. Other
The rates of extinction fluctuated by decade, with a sig- regions with long (or longer) traditions of faunal study
nificant increase in the mean number of extinctions per exhibit similar overall extinction rates to that of North
decade after 1950 (figure 2). The post-1950s increases in Americafor example, in Europe, 3.4% of 531 species are
extinction probably resulted from indirect effects of the extinct or possibly extinct (Freyhof and Brooks 2011), and
postWorld War II baby boom, including demographic in the Mediterranean basin, 3.2% of 253 species are extinct
shifts from rural to urban areas, increased construction (Smith KG and Darwall 2006). Around 43% of the 31,769
of large and small dams, increased alteration of natural fish species on Earth are freshwater fishes (Nelson 2006),
water bodies (e.g., channelization, pollution), and other which equals about 13,661 species, 3% of which would be
consequences of economic growth and industrial expan- approximately 410 extinct freshwater species worldwide.
sion (CEC 2001, McKinney 2002, De Souza et al. 2003). This elementary extrapolation based on the North American
The recent decline in extinction rates is the fourth decadal proportion of extinct fishes suggests that worldwide tal-
decline since 1900, but three of the extinction declines lies of extinct freshwater fishes significantly underestimate
were followed by episodes of increasing or stable extinc- the actual number suggested by current databases (IUCN
tion rates (figure2). 2011)perhaps by several times.
Figure 2. Extinction rates of North American freshwater Figure 4. Lag time in years between the last observation
fishes by decade (n= 60). The solid black circles and of a species and its estimated year of extinction for North
dashed line represent cumulative extinctions and American freshwater fishes. Mean lag time= 3.8 years.
extirpations from 1898 to 2006. The open circles and The closed circles represent extinct species and subspecies,
solid line represent extinctions by decade (range= 011 including undescribed taxa. The open circles represent
extinctions per decade; pre-1950s mean= 2.5; post-1950s extirpated populations (32 taxa had lag times of 0years).
mean= 7.5; t-test for unequal variances, t(7)= 6.16, The fitted black trend line is that described by a simple
two-tailed, p= .0004). linear regression (R= .0994, p< .0001).
of modern with background extinction rates (BERs) will species durations of these archaic fishes. At least two stur-
enable a robust evaluation of these losses. geon species of Pseudoscaphirhynchus are considered criti-
cally endangered in Eurasia (IUCN 2011); if one of these
Background rates of extinction sturgeons disappeared, the mean species duration interval
In their seminal studies, Pimm and colleagues (1995, 2006) for fishes would significantly increase, causing estimates of
demonstrated the utility of comparing modern extinctions E/MSY to increase likewise. If evolutionarily old taxa such
with BERs in birds by estimating the number of extinctions as sturgeons, paddlefishes, or gars became extinct, it might
per million species years (E/MSY). This logical approach be appropriate to divide extinct fishes into two groups
facilitates comparing modern bird extinction rates with archaic and modern bony fishes. The species duration
those of other biotas, and the examination of changes in interval estimated for freshwater fishes (Stanley 1985, 1990)
bird extinction rates in the past 500 years. To estimate the is based on Lyellian percentagesproportions of living spe-
E/MSY, the following must be known: the mean species cies within fossil faunas (Stanley etal. 1980). As was noted
duration interval from origination to extinction (from the in Near and colleagues (2005, 2011) discussions of recent
fossil record) in millions of years, the total number of extant chronogram estimates for centrarchids and percids, the lin-
taxa, the number of modern extinct taxa, and the interval eage derivation estimates are far older than was previously
in years in which modern extinctions occurred. Pimm and known, and it is possible that the mean duration interval
colleagues (1995, 2006) lacked data for the mean species of one extinction every 3 million years (Stanley 1985,
duration interval for birds, so they substituted data from ter- 1990) underestimates, perhaps significantly, the species age
restrial vertebrates (mammals; Pimm etal. 1995, May etal. for freshwater fishes. If that were true, it would make the
1995). They also considered 1 million years as the bench- E/MSY estimates low, possibly by an order of magnitude.
mark interval prior to human impacts. For example, if the mean species duration for freshwater
Pimm and colleagues (2006) specifically posited that fishes is actually closer to one extinction each 11 million
around 1.3% of the roughly 10,000 known bird species have years, the modern to BER estimate for North American
become extinct since 1500, which equals a modern to BER fishes would be 3215E/MSY.
of approximately 26 E/MSY (calculated by multiplying the The ability to compare modern extinction rates with
quotient of the mean species duration interval for birds and BERs facilitates meaningful comparisons of contemporary
total bird diversity [106/104= 100] by the mean annual bird extinction rates among different biotas (Pereira etal. 2010
extinction rate [130 extinctions/500 years = 0.26]). When [and its supplemental material], Barnosky et al. 2011).
shorter intervals over which extinction occurred (e.g., since Most of the bird extinctions investigated by Pimm and
1900) were examined, global extinction rates were as high as colleagues (2006) were of island species, which are inher-
65E/MSY (Pimm etal. 2006). ently susceptible to extinction because of high endemism;
For North American freshwater fishes, the mean species habitat destruction; and the introduction of nonnative
duration interval from the fossil record is 3 million years organisms, including humans. BERs are compared among
(Stanley 1990), the total number of species is 1213, the time world vertebrate groups for the twentieth century in table2.
interval over which modern extinctions were examined is The E/MSY estimate for freshwater fishes in the twentieth
110 years (1900 to 2010), and the number of extinct fish century was nearly twice that of other vertebrate groups.
species is 39 (3 of which are undescribed). The modern to The BER estimated for birds (table 2) is higher than that
BER estimate is 877E/MSY for North American freshwater estimated by Pimm and colleagues (2006) because I used
fishesthe highest estimate reported for contemporary different species duration data for birds (i.e., 2.5 million
vertebrates (Pimm et al. 2006, Pereira et al. 2010 [and its years; Stanley 1990). As was noted in the Current rates of
supplemental material], Barnosky etal. 2011). extinction section, the reported extinction rates for fresh-
Several issues merit a brief discussion relative to the water fishes from other continents appear grossly under-
comparison of modern extinction rates with BERs. First, estimated. If, for example, the continental extinction rate
the actual species richness of North America freshwater for North America (3.2%) mirrors the extinction rates of
fish fauna is not yet known, as is indicated by the lack of an freshwater fishes in other continents, the number of extinct
asymptote in the rate of fish descriptions (figure 1a), and fishes for the twentieth century would be around 384 spe-
it is possible that not all recent fish extinctions are known. cies (instead of 81 in table2) and the twentieth century BER
In addition, fishes are not equal entities evolutionarily or would be 960E/MSY.
with respect to species duration intervals. The latter spans The continental list of extinct fishes from Africa and
several orders of magnitude, from about 10,000years ago to Madagascar differs from the data given in the worldwide
the present for fishes that diverged after the last glaciation assessment of extinct fishes by Harrison and Stiassny (1999),
(Smith GR etal. 2002, Taylor etal. 2006) to over 160mya for in which about 50 haplochromine cichlids from Africa and
extant archaic fishes, such as the longnose gar (Lepisosteus Madagascar were considered possibly extinct. In a recent
osseus; Grande 2010). The loss of species such as sturgeon assessment, Snoeks and colleagues (2011) determined that
or gar would significantly increase the mean duration these species are critically endangered or that their status is
intervals for freshwater fishes because of the tremendous data deficient and in need of further study.
Note: The number of freshwater fishes in 2000 was 43% of about 27,901
total species (Eschmeyer and Fong 2012). Mean species duration is the
species life span in millions of years from origination to extinction;
when it was not known, it was estimated to be 1.0E/MSY, which is also
considered the benchmark extinction rate prior to human impacts (Pimm
etal. 1995). The correct twentieth century background extinction rate for
fishes may be over 900E/MSY (see the Background rates of extinction
section).
Abbreviations: E/MSY, extinctions per million species years.
a
IUCN 2011. bStanley 1990. cPereira etal. 2010. dUetz 2000.
e
Stanley 1985.
century or whether it made it to the twenty-first century. If it sites or whose ranges are truncated by large impoundments
is not found in 5years, the slender chub could be the next fish are probably more vulnerable to future extinction because
to qualify for possibly extinct status in North America. of exposure to multiple stressors (McKinney 2002, McKee
Mexico has a large number of fishes vulnerable to extinc- etal. 2004).
tion in the near future, primarily because of high levels of
endemism. Of the 280 North American fishes identified Conclusions
as endangered, 65 were exclusively from Mexico, 70 were Each continental fish fauna is a unique, globally important
from the United States, and 21 were from Canada (Jelks resource of immensurable worth. The North American fish
et al. 2008). For example, the Ameca River system, noted fauna has tremendous recreational and commercial value,
for its high levels of endemism, has lost 70% of its native as well as aesthetic, scientific, and cultural importance
fish fauna (Lpez-Lpez and Paulo-Maya 2001, Prez- (Helfman 2007, NFHB 2010). In particular, fish represent
Rodrguez et al. 2009). The family Goodeidae has a large important sources of protein for individuals at lower socio-
number of endangered and extinct species in Mexico. Of economic levels worldwide (Helfman 2007). With respect to
the extant Mexican goodeids, 16 were identified as critically scientific and ecological studies, fishes are especially useful
endangered and 7 as endangered (Domnguez-Domnguez for evaluating environmental change, because biologists
et al. 2005); all are small fishes, and most are narrow or know much more about their biology than they do those of
localized endemics exposed to multiple threats. Another other aquatic biotas. Actually, declining fishes represent just
nine Mexican fishes were recently categorized as in danger of the tip of the iceberg regarding losses of freshwater biota and
extinction (Schmitter-Soto 2006). their habitats. Comparatively, mussels and snails are excep-
A frequently cited exponential-decay model used to esti- tionally imperiled, with BERs an order of magnitude greater
mate future extinction rates required recent data on the than that of freshwater fishes.
numbers of threatened and endangered species in order to The exigent issue regarding these extinctions is not so
model future extinctions (Ricciardi and Rasmussen 1999) much the number of missing fishes but the fact that these
and was therefore unable to estimate the number of future fishes disappeared in only 110years (figures 1b and 2). Fish
fish extinctions by 2050. Assuming no near-future cata- extinction rates are currently 877 times greater than BERs,
strophic events, different elementary approaches were used and since 1900, those rates have fluctuated between 556 and
to estimate the numbers of extinct fish species by 2050. 1042E/MSY. These BER estimates are low because they do
The number of currently declining endangered fishes (see not include infraspecific taxa (extinct subspecies or extir-
Jelks and colleagues [2008] appendix 1) plus the number pated populations). Future freshwater fish extinctions in
of currently extinct species equals 113 species. Although North America are estimated to range from 53 to 86 species
it is unlikely that all currently declining endangered fishes by 2050.
would become extinct by 2050, 113 species could be consid- Current estimates of the number of extinct fishes from
ered the upper limit of extinction in a worst-case scenario. all other continents are significantly lower than decadal
Two elementary extrapolations based on the mean annual extinction rates for North America (figure3). In most cases,
extinction rate (MAER) and on the mean annual description these discrepancies represent gross underestimates of true
rate (MADER) yielded the following estimates: The overall extinction levels on those other continents. However, recent
MAER is 0.35 extinct fish species per year (which is more changes in some of the IUCN (2011) data resulted from
conservative than the post-1950s rate of 0.73 species per year; increased caution about the accuracy of previously reported
see figure2). Beginning with 39 extinct species in 2010, the extinction estimates, particularly in the African rift lakes,
MAER extrapolation approximates 53 extinct species by 2050 where funding and logistics reduces the ability to inten-
(an increase of 14 species). The MADER extrapolation based sively sample and where the fauna is taxonomically complex
on 6.7 species described per year yields 1482 species by 2050. (Snoeks etal. 2011). Based on the continental extinction rate
Under the assumption that the continental proportion of of 3.2% for North America, the worldwide loss of freshwater
extinct fishes remains about 3.2% until 2050, the number of fishes may exceed 400 species.
extinct fish species approaches 86 (an increase of 47 species). After 253 years of faunal discovery and documentation
Therefore, by 2050, the number of extinct fishes is estimated (figure1a), the freshwater fishes remaining to be discovered
to range from 53 to 86 species, representing an increase of are more likely to be narrow or localized endemics, cryptic,
35.9%120.5%, with an improbable upper limit of 113 spe- and imperiled (Burkhead and Jelks 2000). The number
cies (a 190% increase). of humans recently increased to 7 billion individuals; the
What is more important to resource managers than totemic effects of our activities on the Earths systems and
estimating the number of future extinctions is identifying processes are quantifiable at global scales, are observable
which fishes are more likely to become extinct in the near from space, and include ongoing biodiversity decline and
future. Of the endangered fishes listed by Jelks and col- loss as well as worldwide changes to geochemical cycles
leagues (2008), those that are narrow or localized endemics and increasing climatic variability (Rockstrm et al. 2009,
and in proximity to major urban areas, transportation cor- Pereira etal. 2010 [and its supplemental material], Barnosky
ridors, future energy development, or resource extraction etal. 2011). The loss of 3.2% of the continental fish diversity
is not trivial and demonstrates that some of our resource Darwin C. 1859. On the Origin of Species by Means of Natural Selection,
practices are detrimental to the persistence of freshwater or the Preservation of Favoured Races in the Struggle for Life. John
fishes and likely to that of other aquatic faunas. Murray.
Davies RG, et al. 2006. Human impacts and the global distribution of
Online data on extinct North American freshwater fishes, extinction risk. Philosophical Transactions of the Royal Society B 273:
as well as any potential errata from this report may be 21272133.
found at the USGSAFS Web site (http://fl.biology.usgs.gov/ De Souza R-M, Williams JS, Meyerson FAB. 2003. Critical Links: Population,
extinct_fishes/index.html). Health, and the Environment. Population Reference Bureau. Population
Bulletin no.58.
Domnguez-Domnguez O, Mercado-Silva N, Lyons J, Grier HJ. 2005. The
Acknowledgments viviparous goodeid species. Pages 525569 in Uribe MC, Grier HJ, eds.
This article is dedicated to eminent scholars, conservationists, Viviparous Fishes. New Life Publications.
and friends: Salvador Contreras-Balderas (19362009) and Eschmeyer WN, Fong JD. Fong. 2012. Species of Fishes by Family/Subfamily
Joseph S. Nelson (19372011). The report is a spin-off prod- in the Catalog of Fishes. (13 June 2012; http://research.calacademy.org/
uct of the American Fisheries Society Endangered Species research/ichthyology/catalog/SpeciesByFamily.asp)
Freyhof J, Brooks E. 2011. European Red List of Freshwater Fishes.
Committee (AFS ESC) Fishes Subcommittee, which was Publications Office of the European Union.
active from 2004 to 2011; all former committee members are Grande L. 2010. An Empirical Synthetic Pattern Study of Gars
recognized for their contributions to this study. In particular, (Lepisosteiformes) and Closely Related Species, Based on Mostly
former AFS ESC members Edmundo Daz Pardo (Universidad Skeletal Anatomy: The Resurrection of Holostei. American Society of
Autonoma de Queretaro), Dean Hendrickson (University of Ichthyologists and Herpetologists. Special Publication no.6; Copeia 10
(suppl.).
Texas), Eric Taylor (University of British Columbia), and Juan Harrison IJ, Stiassny MLJ. 1999. The quiet crisis: A preliminary listing of
Schmitter-Soto (El Colegio de la Frontera Sur) updated or the freshwater fishes of the world that are extinct or missing in action.
provided additional background information on extinct or Pages 271331 in McPhee RDE, ed. Extinctions in Near Time: Causes,
rediscovered taxa. Ian Harrison (American Museum of Natural Contexts, and Consequences. Kluwer Academic.
History and the International Union for Conservation of Hatfield T. 2001. Status of the stickleback species pair, Gasterosteus spp.,
in Hadley Lake, Lasqueti Island, British Columbia. Canadian Field-
Nature) provided comments on the status of rift lake cichlids. Naturalist 115: 579583.
Leo G. Nico (US Geological Survey Southeast Ecological Helfman GS. 2007. Fish Conservation: A Guide to Understanding and
Science Center) kindly translated portions of publications in Restoring Global Aquatic Biodiversity and Fishery Resources. Island
Spanish. Larry Page and William N. Eschmeyer (University of Press.
Florida Museum of Natural History) provided data on North Hocutt CH, Wiley EO, eds. 1986. The Zoogeography of North American
Freshwater Fishes. Wiley.
American and world fish diversity. Kathe Burkhead; Jerry [IUCN] International Union for Conservation of Nature. 2011. IUCN Red
Louton (United States National Museum, retired); Robert List of Threatened Species, version 2011.2. IUCN. (13 June 2012; www.
E. Jenkins (Roanoke College, retired); and Howard L. Jelks, iucnredlist.org)
Kenneth J. Sulak, and Stephen J. Walsh (US Geological Survey Jelks HL, et al. 2008. Conservation status of imperiled North American
Southeast Ecological Science Center) commented on drafts, freshwater and diadromous fishes. Fisheries 33: 372407
Lvque C, Oberdorff T, Paugy D, Stiassny MLJ, Tedesco PA. 2008. Global
and Christine Fadeley navigated the manuscript through the diversity of fishes (Pisces) in freshwater. Hydrobiologia 595: 545567.
US Geological Survey review process. Lpez-Lpez E, Paulo-Maya J. 2001. Changes in the fish assemblages
in the upper Ro Ameca, Mexico. Journal of Freshwater Ecology 16:
179187.
References cited Lundberg JG, Kottelat M, Smith GR, Stiassny MLJ, Gill AC. 2000. So many
Barnosky AD, et al. 2011. Has the Earths sixth mass extinction already fishes, so little time: An overview of recent ichthyological discovery
arrived? Nature 471: 5157. in continental waters. Annals of the Missouri Botanical Garden 87:
Burkhead NM, Jelks, HL. 2000. Essay 1. Diversity, levels of imperilment, and 2662.
cryptic fishes in the southeastern United States. Pages 3032 in Abell May RM, Lawton JH, Stork NE. 1995. Assessing extinction rates. Pages 124
RA, etal., eds. Freshwater Ecoregions of North America: A Conservation in Lawton JE, May RM, eds. Extinction Rates. Oxford University Press.
Assessment. Island Press. Mayden RL. 1988. Vicariance biogeography, parsimony, and evolution in
Burr BM, Mayden RL. 1992. Phylogenetics and North American freshwater North American freshwater fishes. Systematic Zoology 37: 329355.
fishes. Pages 1875 in Mayden RL, ed. Systematics, Historical Ecology, , ed. 1992. Systematics, Historical Ecology, and North American
and North American Freshwater Fishes. Stanford University Press. Freshwater Fishes. Stanford University Press.
[CEC] Commission for Environmental Cooperation. 2001. The North McCrimmon DA Jr. 2002. Sustainable fisheries management in the Great
American Mosaic: A State of the Environment Report. (13 June 2012; Lakes: Scientific and operational challenges. Lakes and Reservoirs:
www.cec.org/Page.asp?PageID=30101&ContentID=16786&SiteNodeID= Research and Management 7: 241254.
438) McKee JK, Sciulli PW, Fooce DC, Waite TA. 2004. Forecasting global bio-
Chernoff B. 1986. Systematics of American atherinid fishes of the genus diversity threats associated with human population growth. Biological
Atherinella. I. The subgenus Atherinella. Proceedings of the Academy of Conservation 115: 161164.
Natural Sciences of Philadelphia 138: 86188. McKinney ML. 2002. Do human activities raise species richness? Contrasting
Contreras-Balderas S, Lozano-Vilano ML. 1996. Extinction of most Sandia patterns in United States plants and fishes. Global Ecology and
and Potos valleys (Nuevo Len, Mexico) endemic pupfishes, crayfishes, Biogeography 11: 343348.
and snails. Ichthyological Explorations of Freshwaters 7: 3340. Miller RR, Williams JD, Williams JE. 1989. Extinctions of North American
Contreras-Balderas S, Almada-Villela P, Lozano-Vilano ML, Garca-Ramrez fishes during the past century. Fisheries 14: 2230, 3238.
ME. 2003. Freshwater fish at risk or extinct in Mxico: A checklist and Minckley WL, Douglas ME. 1991. Discovery and extinction of western
review. Reviews in Fish Biology and Fisheries 12: 241251. fishes: A blink of eye in geologic time. Pages 717 in Minckley WL,