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Transcript
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Razorback Sucker and Humpback Chub in the Colorado River
Abstract
The Colorado River has been called the lifeline of the Southwest United States
because it provides water and electricity to over 25 million people. In fact, a body of
laws collectively referred to as the “Law of the River” allowed the development of
the Southwest because it promoted use of the Colorado River water for industry,
agriculture, and human needs. However, the creators of the “Law of the River” didn’t
consider what impact water development (e.g., building of dams, channels, etc.)
would have on the native fish in the river. Dams built on the Colorado River changed
a number of habitat conditions, including decreasing temperature, interrupting natural
flow regimes, and reducing turbidity. These alterations were a problem for native fish
as they were better suited to live in pre-dam conditions. Although habitat alteration
was a big problem for native fish, introductions of non-native fish species to the
Colorado River were also problematic. Non-native fish are efficient predators on the
eggs and young of native fish and have virtually eliminated younger age classes from
populations of native fish. With little suitable habitat and predation of non-native
fish, species like the Razorback Sucker and Humpback Chub, are in a dire situation.
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Description of Conservation Issue
Razorback Sucker and Humpback Chub are both endangered species in the
Colorado River Basin. The main causes of these species’ decline are habitat
alterations and non-native species introductions (U.S. Fish and Wildlife Service
2000). There are two inherent conflicts in this situation: (1) How do humans use
more Colorado River water for economic development and their daily needs while
still maintaining water levels and flows for endangered fish species? (2) How do
state and federal wildlife agencies protect these endangered species while
simultaneously stocking non-native fish to enhance sports fisheries in the Colorado
River Basin?
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Historic Conditions
The Colorado River was an unobstructed system that flowed freely for over 1,400
miles. Its headwaters in the Rocky Mountains of Wyoming provided for large
flooding events and a siltation of the river in the spring after snowmelt. These
large flooding events carved out shallow sections of river that provided spawning
habitat for many of the thirty-six native species of fish that historically lived in
the Colorado River system. The silt carried by the river inspired the first Spanish
explorers to call it “Rio-Colorado” or Red River (Gelt, 1997). The river was also
much warmer than it is today without the influence of the cooling effects of
hydroelectric dams.
Learn More
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
In the 1800s
Private citizens, state, and federal wildlife agencies began stocking non-native
fish species into the Colorado River to enhance sports fisheries. They stocked
flathead catfish, largemouth bass, bluegill, green sunfish, trout, and many other
fish species into the Colorado River system. Currently, there are forty species of
non-native fish in the Colorado River. The number of introduced fish species
(40) outnumbers the number of native fish species, those that originally lived
there. Native fish species numbers declined dramatically after the introductions
of non-native fish species because non-native fish were efficient predators of the
native species’ young and eggs (U.S. Fish and Wildlife Service 2002).
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
In the 1900s
States in the Colorado River Basin had many disputes over who had rights over the
water in the Colorado River. Each state wanted to establish its own limits on use of
Colorado River water. A body of interstate compacts, federal laws, water contracts,
state laws, a treaty with Mexico, Supreme Court decrees, and Federal and State
administrative actions were developed to resolve these differences. These laws are
collectively referred to as the “Law of the River” and have been very instrumental
in the development of the Southwest United States. The Hydroelectric Dams
provide water and electricity to industry, agriculture, and over 25 million people
living in the Colorado River Basin states (Gelt, 1997). Although these laws were
successful in developing the Southwest, they were also detrimental to native fish
species living in the river. Habitat conditions changed rapidly with the closing of the
gates of the Glen Canyon Dam in 1963. Almost immediately, water temperatures
dropped, flow was interrupted, and silt began being trapped by the dam. As the
habitat in the river changed from a system to which native fish were well adapted to
a system to which they were not well suited, native fish populations started to
decline.
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Present Conditions
The Colorado River today is a reflection of what the “Law of the River” and the
humans who created that body of legislation wanted it to be. It is a series of
connected reservoirs blocked by hydroelectric dams for the use of humans. These
dams have been beneficial for the development of the Southwest, but have changed
the habitat conditions in the river. Now the river is clear and cool; there are few
flooding events in the spring (beneficial for spawning habitats); and there is erratic
flow the rest of the year. The river also provides great opportunities for sportsman
to go fishing for many game fish species, even though most of them are not native
to the system. Endangered Species in the system still face the danger of going
extinct without action from State and Federal wildlife agencies The Colorado River
is vastly different than it was before the influence of man, and this change is a
direct result of the history of human interaction with the river.
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Relevant Research
There is a lot of research that has been conducted on the endangered species of
the Colorado River. What is striking about all this research is that it is very
consistent as to the cause of the declines of Humpback Chub and Razorback
Sucker. It seems that every piece of scientific evidence we have on the
Humpback Chub and Razorback Sucker point to the same challenges of habitat
destruction caused by water development and predation by non-native fish
species. The next few slides provide a study-by-study synopsis of the challenges
these species face as defined by research:
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Life History and Ecology of the Humpback Chub in the Little Colorado and Colorado
Rivers of the Grand Canyon
By: LYNN R. KAEDING AND MARIAN A. ZIMMERMAN
Synopsis:
This study shows that the only viable population of Humpback Chub lives in the Little Colorado,
which is a shallow and warm tributary of the Colorado River. This tributary is protected from
predators because it is too shallow for them to live there. This study also shows that the cold
temperatures in the Colorado River cause nearly complete mortality of embryonic and larval
Humpback Chubs. The researchers of this study suggest that the Little Colorado be protected
from species introductions as it is the only place that Humpback Chub can reproduce and
devastating effects could result from these introductions.
Introduction
History
Science
Conflicts
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Legislative
Effectiveness
Predation by Introduced Fishes on Endangered Humpback Chub and Other Native Species
in the Little Colorado River, Arizona
By: PAUL C. MARSH AND MICHAEL E. DOUGLAS
Synopsis:
This study showed that native fish species represent a significant percentage of introduced
species’ diets. More specifically, this study sampled rainbow trout, channel catfish, yellow
bullhead, black bullhead, and brown trout diets in the Colorado River. Researchers found that
native fish species represented thirty percent of these fish’s diets. Three percent of these diets
were comprised of Humpback Chub. The researchers calculated that each the predator fish they
sampled eat an average of 2.3 Humpback Chubs per week. This means that 1,000 predators will
consume around 4,000 Chubs annually. This predation represents a major negative effect on the
population. Researchers also pointed out the fact that juveniles represented a large portion of the
Humpback Chubs consumed. This study shows how non-native predation not only limits
recruitment, but also decreases the total adult population and reproduction from such.
Introduction
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Ecology of Spawning Humpback Chub, Gila Cypha, in the Colorado River near Grand
Canyon, Arizona
By: OWEN T. GORMAN AND DENNIS M. STONE
Synopsis:
This study describes the spawning activity of Humpback Chub in the Colorado River.
Researchers found that Humpback Chub spawning activity was correlated with peak flows in
April and also with higher temperatures found in tributaries, such as the Little Colorado River.
They stress that temperatures in the Colorado River do not typically get warm enough to induce
spawning activity of Humpback Chub. They also state that spawning sites were correlated with
the structural complexity found in the tributaries of the Colorado River. The researchers state that
since flooding events no longer occur in the Colorado River, there are no forces to carve out the
shallow spawning pools on the banks of the river that provide the structural complexity
Humpback Chubs use to spawn. This study also provides evidence for spawning migrations of
adult Humpback Chub that live in the Colorado River approximately 13 kilometers up the Little
Colorado River.
Introduction
History
Science
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Effectiveness
Effects of a Test Flood on Fishes of the Colorado River in Grand Canyon, Arizona
By: RICHARD A. VALDEZ, TIMOTHY L. HOFFNAGLE, CAROLE C. MCIVOR, TED
MCKINNEY, AND WILLIAM C. LEIBFRIED
Synopsis:
This study looked at the effects of an experimental test flood on the Humpback Chubs species in
the Colorado River. Researchers found that Humpback Chub and native fish species had good
spawning success in the slack water pools created by the flood, but had little overall impact on
the survival of non-native fish species. The flood displaced these species, but they came back
after eight months. The conclusion of this study is that floods may serve to temporarily reduce
non-native species competition with native fish species, but a flood of many more orders of
magnitude would be required to reduce non-native fish substantially.
Introduction
History
Science
Conflicts
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Effectiveness
Population Status of the Razorback Sucker in the Middle Green River (U.S.A.)
By: TIMOTHY MODDE, KENNETH P. BURNHAM, AND EDMUND J. WICK
Synopsis:
The results of this study were that the Razorback Sucker are able to reproduce during high flow
years, but these flows are reduced greatly by the influence of dams. Floods are essential to
Razorback Sucker reproduction because they use the shallow water habitat caused by overbank
flooding to reproduce. This study shows that there is positive recruitment during high flow years,
which reinforces that flooded bottomlands on the Colorado River are important for reproduction.
This study also emphasizes that the increase in introduced fish species populations is closely
associated with the decrease in Razorback Sucker populations.
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Relative Sensitivity of Three Endangered Fishes — Colorado Squawfish, Bonytail, and
Razorback Sucker — to Selected Metal Pollutants
By: KEVIN J. BUHL
Synopsis:
This study looked at metal pollution concentrations and its effect on Razorback Sucker
populations. The researchers found that most EPA regulations on metal pollution were adequate
or had no effect on the Razorback Sucker. They also found that cadmium was an important metal
that has strong implications on Razorback Sucker because it greatly reduced their ability to
reproduce.
Introduction
History
Science
Conflicts
Relevant
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Legislative
Effectiveness
Geomorphology and Endangered Fish Habitats of the Upper Colorado River 1. Historic
changes in streamflow, sediment load, and channel morphology
By: MARK M VAN STEETER AND JOHN PITLICK
Synopsis:
The results of this study showed that peak discharges have decreased 19 – 38% and that annual
sediment loads have decreased 40 – 65% in the Colorado River. It also states that the main
channel of the Colorado River has narrowed an average of twenty meters, which means that 25%
of the area formed by side channels and backwaters has been lost. All of these changes in the
habitat are related to reduced and restricted water flow in the river. This reduced flow caused by
dams has effectively reduced the heterogeneity of the habitat used for spawning by native fish
species in the Colorado River.
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Habitat Use by Hatchery-Reared Adult Razorback Suckers
Released into the Lower Colorado River, California–Arizona
By: RICHARD H. BRADFORD AND SCOTT D. GURTIN
Synopsis:
This study looked at the habitat use by hatchery-reared Razorback Suckers. The results of this
study were that backwater habitats were used the most often among hatchery-reared Razorback.
The second-most important habitat used by Razorbacks was side channel habitats. Main channel
habitats were rarely used by this fish species. Researchers emphasize the need to protect
backwater and side water habitats for Razorback Suckers. They also make recommendations for
stocking of Razorback Sucker in areas that provide a suitable amount of backwater and side
channel habitats.
Introduction
History
Science
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Effectiveness
Conflicts And Debate
The stakeholders of the Colorado River are vast as there are a number of private
citizen organizations in addition to state and federal agencies involved. On the
governmental side, you have Colorado River Basin States fish and game
departments, Colorado River Basin States EPA’s and legislative bodies, the United
States Fish and Wildlife Service, the Army Corps of Engineers, and the United
States Environmental Protection Agency. On the other side, you have private
citizens, private citizen organizations, agricultural operations, industry, and mining
operations. Neither side totally agrees on what needs to be done with the river to
benefit such native fish species as the Humpback Chub or Razorback Sucker. The
two basic conflicts between many of these groups are: (1) One side wants to protect
native fish species by restoring habitat conditions that are beneficial to these fish
while another side would like to use more water or develop land and degrade habitat
further to provide for some facet of human need and (2) One side likes fishing for
game species in the Colorado River System, but the other realizes that these species
have eliminated reproduction of native fish species and have caused their decline
and therefore, this agency or group is for the removal of non-native fish or at least
the elimination of stocking non-native fish.
Introduction
History
Science
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Legislation
Legislative
Effectiveness
Relevant Legislation
There are four relevant laws that apply to endangered
species in the Colorado River Basin:
• The Mining Law of 1872
• Water Law
• Clean Water Act
• Endangered Species Act
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Appendix
About FCF
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History
Science
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Relevant
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Legislative
Effectiveness
The Mining Law of 1872
The price for metals is increasing and many multinational companies are looking to
make mining claims on Federal lands near the Colorado River. Most companies want
to stake a claim on these Federal lands for the rich uranium deposits that are found
near the Colorado River. Even though the Colorado River supplies drinking water for
over 25 million people, there is little protection to stop mining because the Mining
Law of 1872 allows all citizens of the US to locate hard rock or gravel and claim it
for mining (EWG, 2008a). These minerals include, but are not limited to, platinum,
gold, silver, copper, lead, zinc, tungsten, and uranium. The EPA has reported that
mining has contaminated the headwaters of more than 40 percent of Western
watersheds. Furthermore, the Environmental Protection Agency has identified metal
mining as the nation’s leading source of toxic pollution for nine consecutive years
(EWG, 2008b). With metal prices on the rise, it is likely that these mines will be
opened and cause contamination of the Colorado River. This contamination could
have strong negative impacts on fish health in the river.
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Appendix
About FCF
Introduction
History
Science
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Legislative
Effectiveness
Water Law
Most water law is formed by disputes between people who want to use the water for some
purpose. The Western United States uses prior appropriation in which the first person to use
water for a “beneficial use” has rights over the water to limit these disputes. In fact, the
“Law of the River” was formed because of disputes over water usage among the states in the
Colorado River Basin. While each law of “The Law of the River” individually has some
effect on the Humpback Chub and Razorback Sucker, for the purpose of this discussion
we’ll focus on some of the most important legislation and briefly discuss what the other laws
in the “Law of the River” were meant to accomplish.
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The Law of the River
The foundation for the “Law of the River” was the Colorado River Compact of 1922 (Gelt
1997). This Compact divided the Colorado River Basin into Upper and Lower Basins with the
dividing line at Lee’s Ferry, Arizona. The upper states were apportioned 7.5 million acre feet
of flow, and the lower basin was apportioned the same amount of flow with the option of using
an additional 1 million acre feet of flow. The problem is that legislatures apportioned more
water for use by the states than what actually flows through the river. Basically, all water is
apportioned for use by the states and no water is left for fish species habitat. The Boulder
Canyon Project Act of 1928 and the Colorado River Storage Project Act of 1956 authorized
the building of the Glen Canyon Dam, the Hoover Dam, and several other dams for
hydroelectric power and flood control (Gelt 1997). These Acts also had provisions for how
water was going to be used for economic development of the region and put to a “beneficial
use” for humans. The other laws that form the “Law of the River” dealt specifically with how
water was going to be used between states, the U.S. and Mexico, and people within the states.
These laws also focused on how to use the water toward development and “beneficial use” by
humans.
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About FCF
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History
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Legislative
Effectiveness
Clean Water Act
Section 101(a) of the Federal Water Pollution Control Act (i.e., Clean Water
Act; 33 U.S.C. 1251–13287) states that the objective of this law is to restore
and maintain the chemical, physical, and biological integrity of the Nation’s
waters and provide the means to assure the “...protection and propagation of
fish, shellfish, and wildlife... .” This statute contributes in a significant way to
the protection of the Razorback Sucker and Humpback Chub and their food
supply through provisions for water quality standards — protection from the
discharge of harmful pollutants, contaminants [Section 303(c), Section
304(a), and Section 402] and discharge of dredge or fill material into all
waters, including certain wetlands (Section 404) (U.S. Fish and Wildlife
Service 2002).
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About FCF
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Effectiveness
Endangered Species Act
The primary regulatory mechanism for protection of the Razorback Sucker and
Humpback Chub is through Section 7(a)(2) of the Endangered Species Act (ESA),
which states that “Each Federal agency shall, in consultation with and with the
assistance of the Secretary, insure that any action authorized, funded, or carried out
by such agency... is not likely to jeopardize the continued existence of any
endangered species or threatened species or result in the destruction or adverse
modification of habitat of such species which is determined by the Secretary, after
consultation as appropriate with affected States, to be critical...” (U.S. Fish and
Wildlife Service 2002).
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Endangered Species Act (Continued)
The Upper Colorado River Basin Recovery Program (UCRRP) provides a
mechanism for dealing with Section 7 consultations. There are currently no formal
recovery programs in the lower basin, and Section 7 consultations are addressed on
a case-by-case basis (U.S. Fish and Wildlife Service 2002) . None of the recovery or
conservation programs in the Colorado River Basin are regulatory mechanisms that
provide permanent, long-term protection for the species after delisting. In addition
to Federal protection under the ESA, Razorback Suckers and Humpback Chub are
protected by all basin States under categories such as “endangered,” “threatened,” or
“sensitive.” This protection prohibits intentional take-and-keeping or harming in
any way any fish captured incidentally, and may need to remain in place after the
species is delisted (U.S. Fish and Wildlife Service 2002).
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About FCF
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History
Science
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Legislation
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Effectiveness
Effectiveness of the Endangered Species Act
The Endangered Species Act has been a good thing for the Razorback Sucker and
Humpback Chub in the Colorado River. Many of the studies mentioned as
contributing toward the management of these endangered species were funded
through ESA provisions. These studies depended on ESA money to fund their
research, but the ESA depends on them to make the appropriate decisions when
designating critical habitat under Section 7 of the ESA. Critical habitat designations
have allowed for protection from habitat modifications that threaten these fish
species, but also from the stocking of non-native fish species and, in some instances,
the removal of non-native fish species from these areas. It also protects these
species from being taken from the river through fishing or other means. Without the
ESA, the Razorback Sucker and Humpback Chub may very well have gone extinct.
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Appendix
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History
Science
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Legislation
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Effectiveness
Problems with the ESA
While the ESA is important for the protection of the Humpback Chub and
Razorback Sucker, the legislation itself can only go so far to protect and
enhance the Colorado River for these fish species. ESA decisions are based
on best biological information, but as most fisheries biologists know, much
of fisheries conservation is socioeconomic or political (Minckley, 2003). As
is the case on the Colorado River — many factors other than biology
influence most plans and projects for the conservation of these native fish.
These factors contribute to reducing the benefit of the ESA to the species of
concern.
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About FCF
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Problems with the ESA (continued)
The US Fish and Wildlife service is supposed to enforce ESA regulations and
promote sport fishing, but it has trouble balancing these conflicting interests. There is
an inherent conflict between the management of non-native sport fish and recovery of
endangered fishes. Where valued sport fisheries occur, there is an ongoing dilemma
between public demands for maintenance and expansion of fisheries and management
actions to conserve and recover endangered fish (Minckley, 2003). State agencies
have the same problem on the Colorado River, trying to balance private citizen and
companies’ interest with the biological integrity of the system. Unfortunately, much
of the time private citizen and companies who represent much of the support for state
and federal wildlife agencies win out over the interest of the species of concern.
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Problems with the ESA (continued)
Companies typically have more money and political clout than the agency trying to
enforce the regulations, and challenging these companies is very difficult when
trying to protect endangered species. Much of the time these companies interests
will win out over the regulations set forth by the ESA (Minckley, 2003). Legislative
relief and many exemptions have been given to companies and other agencies who
would like to use the Colorado River for economic benefit. Provisions for habitat
management plans and reasonable and prudent alternatives have successfully
pierced the ESA’s armor to allow non-Federal entities to develop and operate
projects with a “take” of listed taxa. This is permitted so long as a species’
existence is not jeopardized and the impacts of these projects are offset in some
form.
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Conclusion
There is no technical solution for solving the problems that State and Federal wildlife
agencies are facing to recover Humpback Chub and Razorback Suckers. Human
interests have long won out to the detriment of our environment. With concrete
penalties and stronger language, the ESA can be revised to fix some of the problems,
but it is not likely that fish and game agencies will have the political clout to reform
this legislation. The ESA is not a failure because it has provided numerous benefits
to endangered fish populations in the Colorado River. The main problem is that
private citizens and companies are not very concerned with the recovery of these
fish. The support from resource users is not present at this time to ensure that
governmental agencies can do more to protect these species.
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THE END
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Resources
•http://www.fws.gov/coloradoriverrecovery/ - Upper Colorado River
Endangered Fish Recovery Program
•http://cpluhna.nau.edu/Biota/fishes.htm - Land Use History of the
Colorado Plateau
•http://www.colorado.edu/conflict/full_text_search/AllCRCDocs/9312.htm - The Upper Colorado River Basin Endangered Fish
Recovery Initiative
•http://www.cowatercongress.org/images/tom%20pitts%20%20upper%20colorado%20river%20endangered%20fish%20recover
y%20program.pdf – USFWS Presentation
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References
Bradford, R., S. Gurtin. 2000. Habitat Use by Hatchery-Reared Adult Razorback Suckers Released into the Lower Colorado River, California-Arizona. North American Journal of Fisheries Management, 20
(1): 154-167.
Buhl, K., J1997: Relative Sensitivity of Three Endangered Fishes, Colorado Squawfish, Bonylail, and Razborback
Sucker, to Selected Metal Pollutans. Ecotox and Env Safety 37: 186-192.
Environmental Working Group. 2008a. Mining Surge Near Colorado River Threatens Drinking Water For 25 Million. < http://www.ewg.org/node/2646> 10/29/08.
Environmental Working Group. 2008b. Without a Paddle:U.S. Law Powerless to Protect Colorado River From Mining. <http://www.ewg.org/sites/mining_google/ColoradoRiver/index.php?nothanks=1>
10/29/08.
Fish and Wildlife Service. 2000. Species information: threatened and endangered animals and plants. <http://endangered.fws.gov/wildlife.html> 10/29/08.
Fish and Wildlife Service. 2002. Razorback Sucker (Xyrauchen texanus) Recovery Goals. U.S. Department of the Interior, U.S. Fish and Wildlife Service, Washington, D.C.
Fish and Wildife Service. 2006. Why some native fish in the upper Colorado River basin are endangered. http://www.fws.gov/ColoradoRiverrecovery/Crwhynnf.htm 10/29/08
Gelt , J., 1997. Sharing Colorado River Water: History, Public Policy and the Colorado River Compact, Arroyo, Volume 10, No. 1, <ag.arizona.edu/ AZWATER/arroyo/101comm> 10/29/08.
Gorman, O. T., and D. M. Stone. 1999. Ecology of spawning humpback chub, Gila cypha, in the Little Colorado River near Grand Canyon, Arizona. Environmental Biology of Fishes 55:115–133.
Keading, L. R., and M. A. Zimmerman. 1983. Life history and ecology of the humpback chub in the Little Colorado and Colorado rivers of the Grand Canyon. Transactions of the American Fisheries Society
112:577–594.
Marsh, P. C., and M.E. Douglas (1997) Predation by Introduced Fishes on Endangered Humpback Chub and Other Native Species in the Little Colorado River, Arizona. Transactions of the American
Fisheries Society: Vol. 126, No. 2 pp. 343–346
Minckley, W. L., P. C. Marsh, J. E. Deacon, T. E. Dowling, P. W. Hedrick, W. J. Matthews, and G. A. Mueller. 2003.A conservation plan for native fishes of the lower Colorado River. BioScience 53:219–
233.
Modde, T., K.P. Burnham, and E.J. Wick. 1996. Population status of the razorback sucker in the middle Green River (U.S.A). Conservation Biology 10(1):110-119.
Pitlick, J., and M. M. Van Streeter, Geomorphology and endangered fish habitats of the upper Colorado River, 1, Historic changes in streamflow, sediment load, and channel morphology, Water Resour.Res.,
34, 287–302, 1998.
Valdez, R. A., T. L. Hoffnagle, C. C. McIvor, T. Mckinney, and W. C. Liebfried. 2001. Effects of a test flow on fishes of the Colorado River in Grand Canyon, Arizona. Ecological Applications 11:686–700.
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About FCF
kim:
Introduction
History
Science
Conflicts
Relevant
Legislation
Legislative
Effectiveness
Glossary
Use more
complete def.
Age
ForClass: Fish in the same age range
heterogeneity
Embryonic: In an early stage of development
Headwater: The source of a river
Heterogeneity: A state of consisting of dissimilar elements
Peak Discharge: The highest rate of discharge of a volume of water passing a given location
Predation: The act of preying by a predator who kills and eats the prey
Recruitment: The number of new juvenile fish reaching a size/age where they represent a viable target for the commercial,
subsistence or sport fishery for a given species
Sediment Load: The solid material that is transported by a stream
Tributary: A stream or river that flows into a larger one
Turbidity: Having sediment or foreign particles stirred up or suspended; muddy
Viable: Capable of life or normal growth and development
Watershed: The region draining into a river, river system, or other body of water
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Introduction
History
Science
Conflicts
Relevant
Legislation
APPENDIX
1) Silt gets
trapped
behind dam
Legislative
Effectiveness
2) Flow is
restricted
by dam
As a result
river
carries
less silt,
has
restricted
flow, and
is much
cooler
3) Intake in
deeper
cooler
region of
lake
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