Pugh 1
Daniel Pugh
3/16/15
Writing 100
Alex Block
Causation Stage, Draft 2
The longfin smelt is a key species, which is affected by the relationship with
humans and their needs for the Sacramento San-Joaquin Delta, and the stress that it
places on the longfin smelt’s living habitat. The longfin smelt or better known as
pirinchus thaleichthys, “is an anadromous smelt (family Osmeridae) found in California’s
bay, estuary, and nearshore coastal environments from San Francisco Bay north to Lake
Earl, near the Oregon border. The San Francisco Estuary and the Sacramento-San
Joaquin Delta supports the largest longfin smelt population in California, and Humboldt
Bay likely ranks second in longfin smelt abundance.”(www.dfg.ca.gov/habcon/cesa) The
longfin smelt has a very short lifespan, living max of usually three years. Most of this
species reach maturity at two years of age and their size ranges from 120 mm to 140 mm
in length, which is standard length for this species of smelt. The adult smelts of this
species spend their adult lives in bays, estuaries, and coastal areas that are near the
shores. They then migrate to freshwater areas in order to spawn and reproduce more
offspring. Adult longfin smelt migrate to freshwater areas and, “Adult longfin smelt
migrate into low salinity or freshwater reaches of coastal rivers and tributary streams to
spawn. Newly hatched larvae are 5 mm to 8 mm long.”(www.dfg.ca.gov/habcon/cesa)
these larvae are then able to swim upstream to the areas necessary for them to grow and
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continue the lifecycle of this particular species, the longfin smelt. The longfin smelt’s
natural habitat is centered on estuaries, saltwater and freshwater areas, and areas with
middle to deeper areas of water. The longfin smelt’s purpose in the food chain is to
regulate the population of smaller organisms such as opossum shrimp (also known as
Mysis relicta). Without the longfin smelt the shrimp becomes overpopulating resulting in
a disruption of the food chain eliminating the longfin smelt as a regulator of the opossum
shrimp and also as being prey for the other predators which depend on the longfin smelt
for their source of food. Therefore, with the longfin smelt inhabiting the delta itself, there
are certain needs that the fish itself need in order to survive and keep the food chain in the
delta balanced.
The longfin smelt is a crucial species in the delta, and it has needs that make it
possible for it to be able to live and thrive successfully. The species itself encounters
many different living conditions like water temperatures and salinities (freshwater to
saltwater) while they proceed through their life cycles and they are rarely found in water
temperatures that exceed 22 degrees Celsius. They are mostly found in the middle water
areas and lower on towards the bottom and are known to migrate up and down the water
column following prey at night. These conditions are low salinity areas/freshwater areas,
areas where the elevation of the water is very deep, seeing as how they occupy only the
mid-to-bottom level of the areas, which they inhabit. The older adult longfin smelts
prefer areas of salinity recorded at 15 to 30 parts per thousand. They also require
freshwater predominantly in order to spawn and survive. These conditions are vital in
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order for the species to survive because there will be many imposed consequences that
will not only reflect on the habitat of the longfin smelt itself such as, lowered water
levels, overpopulation of the opossum shrimp (longfin smelt’s prey) and longfin smelt
being pushed further to the brink of extinction. The longfin smelt is a regulator of the
opossum shrimp, the primary source of their existence. Without the longfin smelt being
able to live in its ideal living conditions which are, water temperatures that are no higher
than 22 degrees Celsius, water levels that are deep due to longfin smelt preferably living
in the middle level to deeper areas of the Sacramento San Joaquin Delta, and also the
salinity levels. When the salinity levels are affected then the Longfin smelt begins to die
off due to their adaptation not being adjusted to salinity levels of greater than 30 parts per
thousand. When the delta is used for human purposes, the salinity, water temperature, and
water depth are most affected and the habitat and life cycle of longfin smelt is distorted.
Thus, causing us to reevaluate if we really need to pull on the delta for human needs as
we do have needs that coincide with the longfin smelts needs as well.
The Sacramento San Joaquin Delta is responsible for many species usage and
supply of water for their daily needs and activities to sustain life and one in
particular is, humans. Humans depend on the delta to supply more than 25 million
Californians with water plus the industry and agricultural side as well. The delta
also helps to support $400 billion dollars worth of the state of California’s economy
as reported by the Kern County Water Agency. The Kern County Water Agency also
states that water that comes from the delta makes its way to the bay area (30%), the
central valley (roughly around 25-40%), and parts of southern California as well
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(30%), with some areas of California which use the delta for water being one
hundred percent dependent on the delta to supply its area with the necessary water
needed to survive. As evident from these numbers, if Californians were to lose this
primary resource of water the results would be quite catastrophic. The numbers as
provided by the Kern County Water Agency state that, if we lost the delta as a
primary source of water would not only flood the counties around it as well as
stretch out and affect other counties further down towards southern California but
will cost California to lost $30-40 billion dollars worth of economical gains within
the first four to five years as well as losing 30,000 jobs which would affect the
economy itself. Californians intake of the delta is key to sustaining the vastly
populated areas in California due to its exponentially large growth rate where the
population will much likely exceed over 50 million people by the year 2100. With
the potential consequences of the loss of the delta as a primary provider of water to
Californians it presents us with the conflict of evaluating whose needs are more
important, the Longfin Smelt’s or Californians.
The problem for the longfin smelt is the affected living conditions, which have
been altered by humans constantly pulling on the delta to supply our many irrigational as
well as recreational needs. The longfin smelt needs certain living conditions in order to
thrive, reproduce, and effectively contribute to the food chain to help prevent the
overpopulation of its prey the opossum shrimp. With the delta being a large contributor to
what Californians do every day as well as a big contributor to the success of agriculture
here in California but also the import and export of agricultural goods out to other places
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around the world, the delta has been stressed and the population of longfin smelt has
experienced a decrease as well. Longfin smelt require certain conditions to live
peacefully and humans require a certain amount of water to do our agricultural duties
(farmers) and daily activities (Californians). Longfin smelts need a certain level of
salinity in order to be able to reproduce successfully. Adult smelts look to migrate to
waters with salinity levels between sixteen and eighteen degrees Celsius in order to
spawn and continue to make more offspring. The water levels themselves have been
affected with most of the delta islands within the delta itself being reduced to ten to
twenty-five feet below sea level. Therefore, telling us that as we continue to pull out
more and more water to irrigate the crops or to supply us with drinking water that the
water levels are slowly being reduced thus, reducing the depth that the longfin smelt has
to live in. The longfin smelt was once one of the most abundant fish in the delta.
Californians have reduced low delta outflow, which in turn has affected the smelt
dramatically. Other key factors as stated by the State Water Project and Central Valley
Project which have caused conflict due to human interference are the numerous water
diversions by the State Water Project (SWP) and Central Valley Project (CVP) which
have been major contributors to the lower Delta outflow. Such diversions also pose a
threat to longfin smelt because of their potential to entrain longfin smelt, particularly
larvae and juveniles, in pumping stations (Kimmerer and Nobriga 2008). The lowering of
the delta had been quite miniscule until the introduction of these two water projects and
these two have reduced the amount of water going out and affecting the living patterns of
the smelt. Another key contributing factor which has reduced the once large population of
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the longfin smelt in the delta is the introduction of predators by us. One introductory
predator that was introduced to the delta thus affecting the longfin smelt life cycle and
taking away its prey was the overbite clam, Corbula amurensis, in the late 1980s which
changed the benthic community and is likely responsible for the observed for the
downward decline of the mysid shrimp. The introduction of non-native copepods may
also be a big contributor to the affected population and decline over the last years. As
stated by Baxter, as there are introduced predators such as striped bass who do not appear
to be a threat to the adult longfin smelt, other predators such as the Mississippi silverside
(Menidia audens) who focus on the eggs and larval of the longfin smelt may be key
contributors to the rapid decline of the longfin smelt. With the introduction of certain
predators to prey on the prey that is the primary source for the longfin smelt, the
population has been critically affected as it looks for scarce resources considering, its
number one resource for food has become prey to another consumer. Thus, reducing the
available prey(mysid shrimp) and other predators who do not focus on eating the longfin
smelt itself but do however focus on targeting their eggs and larvae are contributors to the
decline of the longfin smelt. As these different factors pile up and add to the decline of
the longfin smelt whether they be introduced predators into their habitat, the salinity of
the water being affected due to lowered water levels, or water acts which have reduced
the water level which is ideal for their survival, there are obstacles which stand in the
way of making the necessary decisions on whether to keep this species or continue to
wreck its habitat for the advancement of ourselves and insure that we have water to
continue our survival as it is crucial to our ever growing population. As previously
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discussed with these issues however, there arises some questions that are presented with
every argument that can be made in relationship to whether or not the longfin smelt is
worth saving.
The questions that have arisen in response to this critical issue are many that
propose many different angles on how the endangering of the longfin smelt should be
handled. Many will propose the question of, “Well why is the longfin smelt just as
important as preserving water so that I can have the necessary resource to give to my
family?” Others will argue on the subject matter that the longfin smelt did nothing to
deserve its population and habitat being reduced at an alarming rate and that we need to
look into alternative solutions in order to better preserve the species which has become
classified as endangered. The other questions that have come about is the one that asks,
“What efforts do we make in order to reduce our intake of the Sacramento San-Joaquin
delta and also what other sort of conservation efforts or alternatives do we need to look
into in order to lessen the strain that we are placing on the delta and the species within
them especially the longfin smelt delta?”