Fish and Fish-Eating Birds at the Salton Sea:
Successes and Slumps
Joseph Quintana
Geogarphy-368
H. Jol
Abstract: The Salton Sea is a huge manmade Sea located in the former Salton
Sink. Created by a freak accident of flooding associated with the Colorado
River it gave birth to a controversial new body of water. One thought to be a
new “French Riviera” in the heart of California it quickly died in popularity
once problems began to emerge. Over the past 100 years it has undergone
massive changes to its water content as well as wildlife contribution. As
salinity levels rose, so did the fish population which in turn also changed its
avian population. In the latter half of the 20th century Botulism poisoning
became a major issue and is the source of much debate today.
Introduction
The Salton Sea is, simply put, a disaster. It was born of a freak accident, it has morphed
from a freshwater body of water to a giant toxic sea. In the past fifty years humans have tried to
bring the Sea to life with monetary investments in the millions in attempts to create a thriving
city. All that is left is a few stores and mostly welfare based housing. On any given mid-summer
morning you could wake up and look at the sea to be met with millions of dead fish lining the
shore. People in Los Angeles can smell the stench it emits nearly 150 miles away.
The Sea is home to a complex ecosystem full of birds and fish which interact, at times,
cohesively, and at times in a deadly manner. Because of the destruction of wetland habitats in
California over the past century, Birds are forced to use the Sea as their roosting and migratory
stop over spots. This continued and frequent overuse leads to the quality of habitat declining and
eventually becoming a hazardous environment for these birds, some of which are growing rarer
by the day. The fish population within the sea tells an interesting story that fluctuates and shifts
as the salinity level has increased over the past 100 years. Moving from a freshwater lake to a
Sea with a higher salt content than the ocean has not been a smooth transition and the health of
the wildlife that relies on the Sea has been the victim. This paper will outline a brief history of
the Salton Sea, and then move to an explanation of the fish and bird relationships and its
importance.
Body
History
The Salton Sea has experienced a long history disaster with short pockets of prosperity.
The Sea itself was created through freak accident. In 1905 farmers were attempting to divert the
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Colorado River for agricultural purposes when one of their dams broke and created a massive
flood. The Colorado River flowed into what was then the Salton Sink. The flooding was
eventually blockaded and the river resumed its original course, but not before it gave birth to a
new inland body of water, the Salton Sea. At the time of inception the Sea was approximately
72.5 km long, 30 km wide and 24 meters deep (Boyle, 1996). Since the Salton Sea has no outlet
rivers or tributaries and receives less than 6 centimeters of rainfall per year, it should have slowly
evaporated over time; however it has persisted into present day (Boyle, 1996). The Sea is fed
mainly by a few small rivers and irrigation runoff from the local farms. This irrigation runoff is
full of nutrients, pesticides and leeches in four million tons of salt annually. Over time the giant
freshwater lake that the Colorado originally created, has transformed into what is now an inland
Sea saltier than the Pacific Ocean. Over time this ever increasing salinity level has dictated the
ecology surrounding the sea as well as shaped the human interaction.
Human investment has been up and down since the creation of the Sea. In the 1950s, 60s
and 70s groups of people desired to create a second “Palm Springs” with the Salton Sea at the
center (Metzler and Springer 2004). Through the 80s and into the present, all hope of the resort
boom ever coming to fruition has disappeared. The wildlife associated with the Sea, mostly fish
and fish-eating birds, has also been in every changing periods of success and decline which
mirror the changing salinity levels in the Sea and seasonality.
Necessary Wetlands
The Salton Sea has taken on drastically important status as a necessary wetland in
California. The land that Los Angeles was founded on was formerly a huge marshy area but as
the area developed, the marshes were transformed into usable land to better suit the city
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infrastructure. As the wetlands were removed, the wildlife that resided there had to find new
wetland locations; The Salton Sea provided just that. The Salton Sea is located along the Pacific
Flyway; an essential migratory route for birds in western North America. However, the fact that
the Sea is located along such an important migratory route has further implications than simply
providing a place for the avian population to stop on their way. Because the Sea connects many
bird populations from a wide area, in a relatively small body of water, the health of many species
of birds from all over North America can be traced back to the health of the Salton Sea (Shuford,
2002). As with any water ecosystem, the Salton Sea demonstrates a complicated relationship
between water and wildlife, specifically centered on the fish and bird populations, which is why
they both deserve a more in-depth look.
Wildlife: Fish
Just as the Sea has transformed since its inception, so has the fish population living in it.
The Sea not only received its original water from the Colorado River, but also its original fish
population. The Colorado River washed in populations of Carp, Trout, Bonytail, Catfish, Striped
Mullet and Humpback sucker (Hurlbert, 2007). This population thrived while the water remained
mostly fresh during its early years. However it was short-lived, salinity increased and as early as
1920, levels reached near ocean levels. During those early years it is estimated that the
population exploded and thrived under low salinity and then crashed as salinity increased and
freshwater fish could no longer survive.
As salinity increased over time, the fish population was continually changing. (See Figure
#1) In the 1940s and 50s, Desert pupfish, Striped Mullet, Mosquitofish, and Longjaw
mudsuckers became the dominant species (Hurlbert,2007). Then as Salinity reached Ocean-like
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levels populations of Bairdeiella, Sargo, Corvina and most importantly, Tilapia came to
dominate the Salton Sea (Hurlbert, 2007). These were first originally introduced into the Sea
during the period of time when human monetary investment was quite high. People saw the sea
as an opportunity for game fishing, so they began to release Corvina, among others, into the Sea.
For a while the Sea did support a game fishing industry, and this did draw many people to the
sea. However, over time some, species failed, and others thrived in the Sea. As the Sea moves
into present day, Tilapia continues to dominate the current population, with estimated numbers
around 100 million. The Salton
Sea is believed to be the most
productive Tilapia producing
body of water in the world
(Metzler and Springer 2004).
The climate of the Sea
continually changes, both
annually and seasonally, as does
the Tilapia population. There are
two main variables that play a
role in the Tilapia reproduction;
Figure 1-Biomass, Species, Salinity
salinity levels and water
temperature. Winter water
temperatures drop to the lower end of Tilapia tolerance and are partially responsible for winter
Tilapia die offs (Hurlbert, 2007). However, it is during the summer season where the major die
offs occur. In the summer heat, the water temperature rises and as the temperature rises, the
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amount of dissolved oxygen that can reach the fish decreases, and the fish die from a lack of
oxygen in the water. This absence of oxygen in the water cause die offs numbering in the
millions during the summer months.
In one particular event, 7.6 million
fish died at one time in the Salton
Sea. The summer of 1996 saw the
shores full of dead fish stretching a
kilometer into the ocean (Metzler
and Springer 2004). The die-off of
fish can cause a decay smell that
Figure 2-Fish die-off
permeates the air near the Sea, and even drifts into the Los Angeles area. Recently there have
been multiple instances where Los Angeles is struck with an awful smell that can be traced back
to the Salton Sea. The smell and fish kill are a problem, but it is a byproduct of the fish die off
that is the biggest concern. The high temperatures and salinity that is so prevalent during the
summer months sets the stage for botulism in the fish. (Metzler and Springer 2004)These
contaminated fish then become food for the fish-eating birds in the Sea, and pass on botulism to
the bird population. When botulism gets to the avian population is where the real ecological
disaster lays.
Wildlife: Birds
Birds are another major part of the ecological picture at the Salton Sea. The history of
avian wildlife at the Salton Sea is a complicated one, over time the success and variety of birds
has done its fair share of shifting. From the beginning, bird populations have flocked to the
Salton Sea as it presented an attractive feeding ground where fish were available in high
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numbers. Birds began arriving shortly after the Colorado River brought an unknown amount of
fish into the Sea (Hurlbert, 2007).
As available wetland habitat decreased over time as urbanization grew, more and more
birds began visiting the Salton Sea, simply for the reason that it was the only wetland spot left.
As discussed earlier, the Salton Sea is an important stopover area for birds migrating along the
Pacific flyway (Friend, 2002). This results in heavy bird use and acts as breeding ground for
Avian diseases, this overuse of the Salton Sea increases the vulnerability of the avian population
to any diseases that may be present.
Avian disease is an annual problem at the sea. During the summer months and onset of
high temperatures, birds get sick and die-off just like the fish. When the temperatures are high,
and salinity is rising, Botulism thrives. As the fish become exposed to the Botulism and contract
it, they then pass it on to the birds when the fish are consumed. Botulism is not a recent
phenomenon at the Sea as the Salton Sea has been reporting Avian botulism since 1938, but in
the past few decades it’s become far more severe (Friend, 2002). In the 1990s the sea
experienced large-scale loss of fish-eating birds from Botulism poisoning. The Salton Sea is the
only place in the world to experience this type of event; no other place has reported losses to the
same magnitude (Friend, 2002). Much like the fish die-off in 1996, the birds experienced a
similar die-off event that year. Birds died in huge numbers as they contracted Botulism from
eating the fish or indirectly eating infected maggots. During the summer of 1996 approximately
15-20 percent of the population of White Pelicans in the Western United States died from
botulism poisoning that could traced back to the Salton Sea (Friend, 2002).
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The Salton Sea Wildlife Refuge was set up to be a waterfowl wintering area, however its
use has dramatically changed in recent years. After the massive die-offs of 1996 the Wildlife
Refuge and its workers became more of an annual rescue effort for infected endangered wildlife.
Each summer when the Botulism die-off happens, the Wildlife Refuge employees go and pick up
the dead birds. If the birds were left out, maggots would consume the bird and become a carrier
for the Botulism. Since maggots are unaffected by Botulism they become the main carrier, and
each infected maggot represents another opportunity for a bird to get sick and die. (Metzler and
Springer, 2004). After the sick birds are picked up they are either helped to regain health or, after
dying, are incinerated.
Why all the effort to keep birds from dying off? As mentioned multiple times, the Salton
Sea is an essential stopover area for both migratory and non-migratory birds. If the Sea is
unhealthy, the bird populations suffer. This becomes an issue in the instance of the Brown
Pelican, which is an endangered species in California. The Brown Pelican can’t afford to lose the
population at the Salton Sea because it’s such a high percentage of the total population. If the
dead birds are allowed to further contaminate the Sea, it is possible that diseases could become
widespread as birds leave the Sea for their seasonal destinations, having an unknown effect on
the avian population in these places. Although it is an ecological disaster to have such high bird
and fish die-offs in the sea, it would be an even greater disaster to have this spread outward to
other ecosystems in North America.
Conclusion
There has been constant debate over the years on whether or not to restore the Salton Sea
to a ‘healthy’ body of water. Some want the Sea to be drained, bringing a whole other variable
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into the equation of the already complicated discussion. The Sea has had a rough ‘life’ thus far
and doesn’t appear to have it any easier moving into the future. Currently it is in a state of
damage control when it comes to maintaining the health of its complex ecosystem. In order to
preserve the quality of the avian population in Western North America the Sea needs to continue
to exist and provide a healthy environment for the birds who frequent it.
The debate of what to do with the Sea will continue until someone sees a way to gain
monetary value from it. The needs of the fish and birds will continue to be unmet unless higher
regulation of water inflow occurs. Overall the Sea is currently a mess that needs cleaning up, but
what else did we expect from a manmade lake turned sea with little to no environmental
regulation?
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References
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Fortner, B. 2000. Desert Wetlands. Civil Enginerring, v. 70, p 58.
Friend, M. 2002. Avian disease at the Salton Sea. Hydrobiologia 473:293-306.
Hart, C.M., M.R. Gonzalez, E.P. Simpson and S.H Hurlbert. 1998. Salinity and fish effects on
Salton Sea microecosystems: zooplankton and nekton. Hydrobiologia v. 381 p. 129-152.
Hurlbert, A.H., T.W. Anderson, K.K. Sturm and Sh.H. Hurlbert. 2007. Fish and fish-eating bird
at the Salton Sea: a century of boom and bust. Lake Reservoir Management v. 23 p.469499.
Schwabe, K.A., P.N. Schuhmann, K.A. Baerenklau and N. Nergis. 2008. Fundamentals of
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Shuford, W.D., N. Warnock, K.C. Molina and K.K Stur. 2002. The Salton Sea as critical
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Figure 1.
Hurlbert, A.H., T.W. Anderson, K.K. Sturm and Sh.H. Hurlbert. 2007. Fish and fish-eating bird
at the Salton Sea: a century of boom and bust. Lake Reservoir Management v. 23 p.4965.
Figure 2.
Jim Lo Scalzo / EPA MSNBC.com
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