Discussion Questions:

Before watching the video:

• What species do you think might be affected by salmon?
• In what ways might these species be impacted by the presence or absence of salmon?

After watching the video:

• In the video, rancher and river guide Jerry Myers says, “You understand by living out here that things are connected and a big, huge part of that is salmon.” Provide examples from the video to support this statement.
• How do bears, birds, invertebrates and trees each benefit from the presence of salmon?
• In the video, author David James Duncan states, “As much as any species of plant and animal in the Pacific Northwest, if this creature is removed from the tapestry, the tapestry will unravel.” Provide reasons to support or refute the statement.
• Why are scientists depositing salmon carcasses and artificial substances into streams? How are they evaluating the impact of these efforts?

Background Essay:

Salmon live in the northern Atlantic and Pacific Oceans. Most are anadromous, meaning they are born in freshwater, migrate to the sea where they live for most of their lives, and then return to freshwater streams to spawn. In recent years, the number of salmon has decreased dramatically due to a combination of natural and human-related factors. In the Colorado River, the salmon population is approximately 3% of what it was in the early 1800s.

Some factors posing threats to salmon are rising stream and river temperatures, due to climate change; pollution, which is damaging and sometimes deadly to salmon and their prey; overharvesting (through commercial fishing, etc.); natural predators; and dams on the rivers, which obstruct passage to spawning areas. For example, the Hells Canyon Complex, located on the Oregon-Idaho border and completed in 1967, includes three dams, which prevent passage of salmon to the Upper Snake River Basin.

When salmon are removed from an ecosystem, the number of grizzly bears decreases. Other species, such as mink, orcas, birds, river otter and microorganisms, which depend on salmon for food, also suffer when the number of salmon declines.  The decrease of these animals, in turn, impacts plant life in forests and mountains. For example, bear droppings and salmon carcasses, which bears leave in the forest and mountains, are rich in both phosphorous and nitrogen, and support plant life. When the number of bears decreases, the amount of salmon-generated nutrients plants receive from bears is reduced as well.

In order to increase the number of salmon, scientists have created fish hatcheries, which produce, raise and release salmon into the wild. Columbia basin hatcheries release more than 100 million salmon into the Columbia River and its tributaries each year.

For more information, go to:

• Grizzly Details: Salmon Collapse Could be Bad News for Bears
• Pacific Salmonids: Major Threats and Impacts
• Salmon/ Salmoniformes

National Science Education Standards:

Grades 9-12:

Content Standard C: Life Science

Fundamental concepts and principles that underlie this standard include:

• The Interdependence of Organisms
  • Energy flows through ecosystems in one direction, from photosynthetic organisms to herbivores to carnivores and decomposers.
  • Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
  • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
  • Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

Content Standard F: Science in Personal and Social Perspectives and Technology
Fundamental concepts and principles that underlie this standard include:

• Science and Technology in Local, National, and Global Challenges
  • Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.

Discussion Questions:

• What draws Pacific Northwest salmon back to freshwater sources to spawn?
• Describe the different habitats of Pacific Northwest salmon.
• How did Redfish Lake get its name? Which species of salmon calls this lake home?
• Briefly describe the life, spawning process and death of Pacific Northwest salmon.

Background Essay:

Most salmon are anadromous, meaning they are born in freshwater, migrate to the sea where they live for most of their lives, and then return to freshwater streams to spawn. Adult salmon stop feeding when they enter fresh water and survive on stored body fat.  Salmon return to the streams where they were born for the spawning process, with some species, such as Sockeye and Chinook salmon, travelling up to 1,000 miles to spawn. Researchers believe salmon use their sense of smell to help locate their home streams.

To begin the spawning process, the female salmon lays her eggs in a redd (nest), up to 18 inches deep, which she digs in the gravel stream beds with her tail. After a male fertilizes the eggs, the female covers the hole and digs a new one, where she deposits more eggs. This process continues until she has laid all her eggs. Females can lay up to 8000 eggs and deposit their eggs in up to 7 different holes. After spawning, all male and female Pacific salmon die within a few weeks.

The number of wild salmon in the Pacific Northwest has decreased dramatically over the past 200 years due to a combination of natural and human-related factors. Many species of salmon in the Pacific Northwest are listed as threatened or endangered on the Endangered Species List. In the Colorado River, the salmon population is approximately 3% of what it was in the early 1800s. Some factors posing threats to salmon are rising stream and river temperatures, due to climate change; natural predators; pollution; overharvesting (through commercial fishing, etc.); and dams on rivers, which obstruct passage to spawning areas.

In order to increase the number of wild salmon, scientists have created fish hatcheries in the Pacific Northwest, to produce and raise millions of salmon each year, which are then released into the wild. The hatcheries take adult salmon from spawning grounds, remove eggs from the female salmon, fertilize them with milt (white liquid containing sperm), and incubate the eggs in plastic bags and PVC pipes. After about a year or more, they release the salmon into the wild. After these salmon are released, they are considered part of the wild salmon population.

For more information, go to:

• Nature: Salmon: Running the Gauntlet:
  • Salmon Lifecycle
  • Salmon Facts
• Interactive Salmon Lifecycle
• Salmon/ Salmoniformes
• Wild Salmon Spotlight: Life in the Pacific/ Salmon Life Cycle

National Science Education Standards:

Grades 9-12:

Content Standard C: Life Science

Fundamental concepts and principles that underlie this standard include:

• The Behavior Of Organisms
  • Multicellular animals have nervous systems that generate behavior. Nervous systems are formed from specialized cells that conduct signals rapidly through the long cell extensions that make up nerves. The nerve cells communicate with each other by secreting specific excitatory and inhibitory molecules. In sense organs, specialized cells detect light, sound, and specific chemicals and enable animals to monitor what is going on in the world around them.
  • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
  • Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.

Discussion Questions:

• What do you think about the methods officials are using to protect salmon from pikeminnow and sea lions?
• Do you think officials should build a new island for the terns and cormorants in order to keep them from eating salmon? If not, what actions (if any) do you think should be taken?
• How are scientists keeping track of their progress in increasing the salmon population?

Background Essay:

In the past 200 years, the number of salmon in the Pacific Northwest has decreased dramatically due to a combination of natural and human-related factors. Many species of salmon in the Pacific Northwest are listed as threatened or endangered on the Endangered species list. In the Colorado River, the salmon population is approximately 3% of what it was in the early 1800s. Some factors that pose threats to salmon are rising stream and river temperatures, due to climate change; pollution, which is damaging and sometimes deadly to salmon and their prey; overharvesting (through commercial fishing, etc.); dams on the rivers, which obstruct passage to spawning areas; and natural predators. Four species that provide serious threats to Pacific Northwest salmon are: double-crested cormorants, Caspian terns, sea lions and pikeminnow.

• Pikeminnow: Scientists believe fish hatcheries (which produce, raise and release salmon into the wild) and dams have directly contributed to increases in pikeminnow populations. Hatcheries release large quantities of juvenile salmon into the water at once. Salmon often get disoriented after passing through the fish ladders at the dams and fall victim to pikeminnow, which wait below the dam and feed on the salmon as they pass through.  In 1991, the northern pikeminnow management program began, which pays bounty hunters to fish for pikeminnow, in order to protect endangered salmon species. As a result of the program, more than 3 million pikeminnow have been removed from the Columbia and Snake Rivers and the amount of juvenile salmon and steelhead consumed by pikeminnow has decreased by 50%. Note: A bounty involves the payment of money to encourage people to remove a species that has been identified as a danger to others. This stems from a long tradition of paying people to remove species that pose a threat. Some species that have been targeted by bounty hunters include: coyotes, crows, foxes, gophers, rats, rattlesnakes, skunks and wolves.

• Caspian Terns and Double-Crested Cormorants: Cormorants and terns on East Sand Island at the mouth of the Columbia River eat about 20 million young salmon a year. The island, owned by the US Army Corps of Engineers, houses the largest known nesting colonies of double-crested and Caspian terns in the world (approximately 13,600 breeding pairs of cormorants and 8300 breeding pairs of Caspian terns in 2010). The US Army Corps of Engineers is currently planning to relocate half the tern population to other sites in Oregon and California by 2015.

• Sea Lions: Sea lions eat thousands of salmon and steelhead populations each year, while the fish are waiting to enter the ladders at Bonneville Dam on the Columbia River. In order to protect salmon and steelhead populations, officials first authorized the use of non-lethal means to scare away the sea lions, as depicted in the “Extreme Measures” video resource. Despite these efforts, however, the problem persisted and, in March 2008, the federal government gave fish and wildlife officials in Washington, Oregon and Idaho the permission to kill up to 85 sea lions each year below Bonneville Dam in order to control the population.  In addition to killing the sea lions, states try to relocate sea lions to aquariums and zoos, when possible. This decision to kill one species to protect another has been challenged by the Humane Society and other animal advocacy groups, who state that the sea lions are not as big a threat to salmon as other factors, such as overfishing by humans.

For more information, go to:

General information about Salmon’s Predators:

• Predation Challenges Faced by Columbia River Salmon

Terns and Cormorants:

• Columbia River Sea Lion Management
• East Sand Island
• Oregon Environmental News

Sea Lions:

• Sea Lions and Bonneville Dam
• “Sea lions are a protected species, whereas salmon are endangered.”

Pikeminnow:

• Northern Pikeminnow Projects
• The Northern Pikeminnow Management Program
• Pikeminnow program reaching goal as predicted by modeling
• Anadromous Fish Predation Strategies, Actions, and Metrics

National Science Education Standards:

Grades 9-12:

Content Standard C: Life Science

Fundamental concepts and principles that underlie this standard include:

• The Interdependence of Organisms
  • Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
  • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
  • Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.
• The Behavior Of Organisms
  • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.

Content Standard F: Science in Personal and Social Perspectives and Technology
Fundamental concepts and principles that underlie this standard include:

• Science and Technology in Local, National, and Global Challenges
  • Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.

Discussion Questions:

• How closely do brown bear cubs follow their mothers? Why do they do so?
• Why do brown bears prefer eating female salmon to male salmon?
• Do adult brown bears prefer to hunt together or individually? How does this affect their interaction during the salmon run?
• Why is it so essential for brown bears that they consume as many fish as possible during the salmon run?
• What are the challenges and dangers faced by mother bears during the salmon run?

Background Essay:

The brown bear is the most widely distributed species of bear in the world, found in the northern regions of North America, Europe, and Asia. It is also the most broadly defined of bear species, with subspecies ranging from the smaller 350 pound “grizzlies” found in mountainous inland regions to the massive 1700 pound “Kodiaks” native to coastal lowlands regions like southern Alaska.

Mating season for brown bears lasts from early May through late July, although a process of “delayed implantation” allows a pregnant female to actively hunt, fish, and forage for several months before embryo gestation begins. For brown bears on the coastal plains of Alaska, the annual culmination of this feeding season is the “salmon run,” during which salmon swim upstream to spawn and die in the rivers where they were hatched. For this, the entire brown bear population descends in concentrations of up to several dozen to fish in the teeming streams.

Brown bears are omnivores, meaning they will eat whatever is available, from plants to animals to insects. While their smaller grizzly cousins in Wyoming’s Yellowstone Park consume half their annual calorie intake by eating up to 40,000 moths a day, Alaskan brown bears rely heavily on the fatty calories of salmon and salmon roe (eggs), consuming up to 40 pounds a day to see them through the long and lean months of winter hibernation, during which time they will lose up to half their body weight.

During hibernation—or “dormancy”—pregnant female brown bears give birth to litters of between one to four cubs, which generally weigh less than 1 pound each at birth. The cubs feed on their mother’s milk through the spring and into the summer, until they reach a weight of between 15 to 20 pounds and are able to learn fishing, hunting, and foraging skills from their mother.  These skills are acquired by following and observing their mother over the course of two to four years, during which time the mother avoids male bears, which are known to kill and eat cubs. Male brown bears take no part in raising their own cubs.

Being at the top of the food chain with no need for safety in numbers, brown bears are generally solitary animals. Their concentration along rivers during the salmon run provides wildlife researchers with rare opportunities to observe their social interactions, which include physical competition among females for males, females teaching their cubs survival by demonstration, and female protection of their cubs against larger and aggressive males.

National Science Education Standards:

Life Science, Content Standard C

As a result of their activities in grades 9-12, all students should develop understanding of

• Interdependence of Organisms
  • Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
  • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
  • Matter, Energy, and Organization in Living Systems
    • The distribution and abundance of organisms and populations in ecosystems are limited by the availability of matter and energy and the ability of the ecosystem to recycle materials.
    • Behavior of Organisms
      • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
      • Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.

Discussion Questions:

• Considering that they are excellent swimmers, why is thin, melting ice such a problem for polar bears?
• Given current rates of pack ice loss, how much longer until the entire polar ice cap has melted?
• Considering how effectively polar bears have evolved to survive in their harsh arctic environment, why is it unlikely that they’ll be able to adapt to their new, warmer world?

Background Essay:

The polar bear is both the world’s largest bear and largest land carnivore. Although born on land, polar bears are excellent swimmers, spending so much of their time at sea and on sea ice that their scientific name—“Ursus maritimus”—translates to “maritime bear.”  While closely enough related to the brown bears more common in temperate zones that rare interbreeding has been documented, polar bears have evolved unique adaptations to their arctic and largely aquatic environment: a longer nose helps warm cold air; smaller ears reduce radiated heat loss; large, scooped feet distribute weight when walking on ice and provide better propulsion when swimming; and a thick layer of blubber provides insulation, buoyancy, and sustenance when food is scarce.

Polar bears possess an extremely keen sense of smell, and are able to detect their primary food source—ringed and bearded seals—up to a mile distant. They primarily hunt at and around the edge of pack ice—the ice shelf that extends in winter months from land—often sneaking up and catching their prey as they surface in ice holes to breathe. When the pack ice recedes in summer and early fall and polar bears are unable to hunt seals, they live primarily off their fat reserves. Polar bears have been known to supplement their diet with a wide variety of plants and other animals, but their digestive systems are specially adapted to seal meat and blubber, and cannot derive sufficient caloric intake from other sources.

Because of their reliance on seals, polar bears are especially vulnerable to the polar warming associated with global climate change. The relatively thin pack ice shelf from which polar bears hunt seals is climatically fragile; rising temperatures melt this ice earlier and further with each passing spring, forcing polar bears to land before they have amassed sufficient fat reserves to survive the lean summer and early fall. Reductions in the thickness and area of pack ice also force bears to swim more frequently and for longer distances in search of food, further depleting their energy and occasionally leading to drowning.

While some may insist on debating the causes of climate change, its consequences on the worldwide polar bear population are undeniable. For example, polar bears’ feeding season in the western Hudson Bay is three weeks shorter than it was 30 years ago; in the same period, the polar bear population has declined over 22%, with the average weight of pregnant females dropping 20%. This insufficient nourishment also leads to lower reproductive rates among adults and lower survival rates among cubs.

National Science Education Standards:

Life Science, Content Standard C

As a result of their activities in grades 9-12, all students should develop understanding of

• Biological evolution
  • Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.
  • Interdependence of organisms
    • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
    • Matter, Energy, and Organization in Living Systems
      • The distribution and abundance of organisms and populations in ecosystems are limited by the availability of matter and energy and the ability of the ecosystem to recycle materials.
      • Behavior of organisms
        • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
        • Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.

Science in Personal and Social Perspectives, Content Standard F

As a result of activities in grades 9-12, all students should develop understanding of

• Environmental quality
  • Materials from human societies affect both physical and chemical cycles of the earth.
  • Many factors influence environmental quality. Factors that students might investigate include population growth, resource use, population distribution, overconsumption, the capacity of technology to solve problems, poverty, the role of economic, political, and religious views, and different ways humans view the earth.
• Natural and human-induced hazards
  • Human activities can enhance potential for hazards. Acquisition of resources, urban growth, and waste disposal can accelerate rates of natural change.
  • Some hazards, such as earthquakes, volcanic eruptions, and severe weather, are rapid and spectacular. But there are slow and progressive changes that also result in problems for individuals and societies. For example, change in stream channel position, erosion of bridge foundations, sedimentation in lakes and harbors, coastal erosions, and continuing erosion and wasting of soil and landscapes can all negatively affect society.
  • Natural and human-induced hazards present the need for humans to assess potential danger and risk. Many changes in the environment designed by humans bring benefits to society, as well as cause risks. Students should understand the costs and trade-offs of various hazards—ranging from those with minor risk to a few people to major catastrophes with major risk to many people. The scale of events and the accuracy with which scientists and engineers can (and cannot) predict events are important considerations.

• Science and technology in local, national, and global challenges
  • Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.

Discussion Questions:

• Why are humans more likely to encounter black bears than brown bears in the streets and backyards of Anchorage?
• What measures could be taken to reduce the black bear presence in Anchorage? Could these measures be considered our own “adaptations” to black bears, just as they’ve adapted to us?
• How large is the “home range” of a mother black bear and her cubs?
• What adaptations to urban life might future generations of black bears exhibit?

Background Essay:

With close to 300,000 residents, Anchorage is Alaska’s largest city, but it is still a relatively small enclave of human settlement in the vast Alaskan wilderness that surrounds it. While this untamed natural environment is perhaps Anchorage’s biggest attraction, it also presents the city with some unique challenges–not least of which is residents’ sometimes uneasy co-existence with bears.

While the approximately 60 brown “grizzly” bears local to Anchorage tend to avoid humans, preferring to remain in the woods and salmon-filled streams on the outskirts of town, the 200-300 strong population of smaller black bears has proven much more adaptable to urban environments. The black bears’ foraging and scavenging skills–originally developed to better locate carcasses and other sustenance in often harsh sub-arctic environments–are well suited to locating easy meals in unsecured garbage cans dispersed throughout Anchorage’s residential neighborhoods.

Anchorage residents are divided about how best to deal with the black bears. Their presence is regarded by many as a charming–if occasionally inconvenient–element of their uniquely natural environment. The bears aren’t hunting for people, they maintain, but rather left-behind food scraps, and they are fairly easily scattered back into the woods. Those with this more permissive perspective are more likely to accept their own relative newcomer status to Alaska and adapt themselves to the wildlife–including black bears–more native than themselves.

On the other side of the debate are those who argue for stricter controls on the bear population by allowing freer hunting of the animals. They point to a rising incidence of human-bear encounters as the human population grows and pushes out further into the wilderness. While violent encounters have been rare–mostly involving larger and rarer grizzlies–black bears have become very common sights, and many residents are concerned about how future generations of these readily adaptive black bears will interact with humans. Unlike the more solitary and evasive grizzlies, black bears have lived unhunted among Anchorage’s neighborhoods for years, growing accustomed to humans, and perhaps no longer having what many would consider to be a healthy respect for us.

What most people in Anchorage can agree on is that greater public awareness of bear behavior is necessary. The Alaska Department of Fish and Game has conducted a door-to-door outreach campaign to heighten awareness of what attracts bears and how to avoid provoking dangerous reactions from them, and laws have recently been passed prohibiting trash from being put out except on pickup day.

National Science Education Standards:

Life Science, Content Standard C

As a result of their activities in grades 9-12, all students should develop understanding of

• Biological evolution
  • Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.
  • Interdependence of organisms
    • Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
    • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
    • Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.
    • Behavior of organisms
      • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
      • Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.

Discussion Questions:

• How do you think the turtles know how to successfully navigate and return to their home beach at Cayo Largo?
• What are the advantages of the turtles laying their eggs at night?
• What impact does Cuba’s growing tourist industry have on the sea turtle population?
• Why is it a problem for sea turtles to be exploited on the black market?
• How are traditional nesting beaches affected by development and pollution?

Background Essay:

Cayo Largo is a small island in the Canarreos Archipelago, approximately 80 miles from the main island of Cuba.  There are no permanent residents of Cayo Largo – hotel and resort workers live on nearby Isla de la Juventud or the mainland.  Even the sea turtles, so dependent on the white sand beaches of Playa Sirena, visit Cayo Largo just once a year.  Three species of sea turtle return to their birthplaces on Cayo Largo between April and September each year: the hawksbill (Eretmochelys imbricata), the loggerhead (Caretta caretta), and the green turtle (chelonia mydas).  The green turtle population is the largest turtle population on the island.

The life of a green turtle is simple, but not easy.  Cuba’s turtles hatch on the beach, and dodge a variety of predators from the land and air as they make their way to the Atlantic Ocean.  Those hatchlings that make it to the sea spend as long as five years living in the open ocean, far from the shore.  As the turtles mature, they return to coastal areas, seeking out shallow, grassy waters.  Adult turtles will move even further inland, preferring inshore bays, lagoons, and shoals.  Many turtles will find one favorite spot, and travel only between that location and Playa Sirena for their entire lives.

Female green turtles return to the waters surrounding the nesting grounds at Cayo Largo once every two to four years; males make the trip every year in search of potential mates.  Once the male and female turtles mate in the water, the females climb on to the beach to create a nest in which to lay their eggs.  Forty-five to seventy-five days later, the eggs will hatch and the cycle begins anew.

Cayo Largo is the most important reproduction site for green turtles in all of the Caribbean and the Gulf of Mexico.  As a result, it is extremely important to preserve the beach conditions at Playa Sirena.  Threats to the beach include increased tourism and increased land development, both of which would reduce the amount of available land and increase the amount of artificial light, which is particularly detrimental to the adult turtles and the hatchlings.

Illegal hunting and poaching are also threatening Cuba’s sea turtle population.  Both domestically and internationally turtle meat, eggs, and shells are considered to be specialty items capable of bringing in large amounts of money on the black market.  Laws have been in place for several years banning the international trade of turtle products, and Cuba banned all harvesting of sea turtles and their eggs in 2008.  Conservationists and sea turtle hatcheries on Cayo Largo are working to preserve the hawksbill, loggerhead, and green turtle populations.

National Science Education Standards:

Life Science

Content Standard C

THE INTERDEPENDENCE OF ORGANISMS

Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

Discussion Questions:

• Observe and note the different shapes of coral present in the ocean reefs.  Why do you think coral grows in these various shapes?
• Why are Cuba’s coral reefs thriving?
• How might different countries and environmental groups around the world address the threats facing coral reefs today?
• Why is elkhorn coral so special to Cuba’s coral reefs, and the Caribbean region?

Background Essay:

Even though at first appearance corals may look like plants or even rocks, they are in fact animals, related to sea anemones and jellyfish.  Corals live in colonies of genetically identical, multicellular organisms called polyps.  The polyps secrete skeletons of calcium carbonate that form the hard structure we recognize as large corals and coral reefs (and so often mistake for rocks).  Corals are usually found at shallow depths in tropical waters, and depend on sunlight to survive.  They feed on small organisms including plankton and tiny fish, and many corals are dependent on a specific type of algae which helps produce energy as well as assisting with calcification of the corals’ skeleton.  Coral structures can grow in many different shapes, some resembling brains, cabbages, table tops, antlers, wire strands, or pillars.

Coral reefs, the large structures built out of millions and millions of coral skeletons over time, are extremely diverse ecosystems that are home to thousands of species.  It is estimated that 25% of all marine species live in and around coral reefs, including over 4,000 species of fish, 700 types of coral, and thousands of other plant and animal species.  The most common type of coral reef is called a fringing reef, found near coastlines of islands and continents, separated from the mainland by a small channel or lagoon.  These are the types of coral reefs found in and around Cuba.  Other types of coral reefs include barrier reefs, atolls, and patch reefs.

Cuba is home to large fringing coral reefs at Archipelago de los Colorados along the northwest coast, and the Jardines de la Reina in the south.  These reefs are home to the largest fish populations in Cuba – possibly even in the entire Caribbean!  However, these fish populations are consistently sought out by local, touring, and commercial fishermen, and overfishing is the main threat currently facing Cuba’s coral reefs.  As a result, fishing is banned in the area, specifically a 386-square mile area surrounding the Jardines de la Reina, now set aside as a marine reserve area.

Coral reefs are extremely sensitive to environmental changes, and depend on clear, clean saltwater to survive.  Pollution and agricultural runoff can have a huge impact on the health of a coral reef.  In this sense, Cuba’s Communist government may have inadvertently helped protect the Cuban reefs for many years, by preventing the flow of fresh water to the sea as well as strictly limiting the availability and use of fertilizer and pesticides.  However, as Cuba begins to open its doors to the rest of the world, increased commercialism and tourism is once again increasing levels of pollution, sedimentation, and development in coastal area, which creates a negative effect on the corals.

National Science Education Standards:

Life Science

Content Standard C

THE INTERDEPENDENCE OF ORGANISMS

Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.

Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

Discussion Questions:

• Observe and note the different ecosystems present on the island of Cuba.  How do all of these different ecosystems function together on the relatively small island?
• How do you think the bee hummingbird finds enough food to consume up to half of its body weight each day?
• What do you think the advantages and disadvantages might be of the polymitas brightly colored shells?  Explain.
• Why do you think Cuba is home to so many of the smallest animals in the world?

Background Essay:

Cuba’s wildlife is varied and unlike wildlife anywhere else in the world.  This is no coincidence – the island, while close to its North and South American neighbors, has been evolving in isolation for thousands of years.  Extraordinary things tend to happen to species evolving in isolation; the unique combination of predators and competition for resources – or, often times, the lack thereof – allows species to adapt in ways they never would on the mainland.  Species adopt new characteristics, behaviors, or patterns that distinguish them from their mainland counterparts.

In some cases, island species move in the direction of gigantism, as the lack of competition and predators allows them to use all available resources and grow as large as possible.  In other cases, such as in Cuba, species will tend toward dwarfism, becoming smaller and conserving resources.  Dwarfism has its advantages, as it enables organisms to absorb nutrients and energy more efficiently, hide from predators more easily, and ably cope with stressful environmental conditions.  This drastic evolutionary size change in species is known as Foster’s rule, or the island rule (as the phenomenon is a core principle of island biogeography).  Furthermore, the size change in species can happen very quickly on islands, much more quickly than evolutionary changes in mainland species.  Mutations and adaptions spread through generations rapidly since there is a much smaller gene pool in the isolated island environment.

Thanks to the special evolution that has taken place on Cuba, the island is now home to some of the smallest and most interesting species on Earth.  The bee hummingbird, known locally as the zuzuncito, is the smallest bird in the world – named because it is no bigger than a honeybee!  This tiny bird is often mistaken for an insect, and is thus prey for larger birds, frogs, fish, and tropical spiders.  Cuba is also home to the second smallest frog in the world, the Mount Iberia Eleuth.  This miniscule frog, only half the size of a dime, lives in two relatively small regions of the country and requires a great deal of humidity to survive.  Other dwarfed species endemic to Cuba include the world’s smallest scorpion, one of the world’s smallest owls, and extremely small varieties of bats.

The unusual evolutionary trends of Cuba extend not only to dwarfed species, but to animals with other unique characteristics.  Perhaps the greatest example of this are the polymitas, or Cuba’s painted snails.  These snails are known for their vibrantly colored shells, which come in a variety of dazzling hues and, of course, are found nowhere else in the world.

Unfortunately, several of Cuba’s distinctive endemic species are becoming or are already threatened.  This is due to a variety of factors, many of them caused by human activity: habitat loss, deforestation, agricultural development and mining, and tourism.  The polymitas are also “hunted” for their shells, popular as jewelry and as collectors’ items, which seriously threatens their populations.  As Cuba continues to open its doors to the world, its great diversity of plant, reptile, bird, and mammal species will be further threatened by human interference.

National Science Education Standards:

Life Science

Content Standard C

BIOLOGICAL EVOLUTION

[See Unifying Concepts and Processes]

• Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.

The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.

THE INTERDEPENDENCE OF ORGANISMS

Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.

Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

GRADE LEVEL: 8-10

TIME ALLOTMENT: Two or three 45-minute class periods

OVERVIEW: In this lesson, students use segments from Nature: Salmon: Running the Gauntlet to explore ways in which humans have impacted salmon populations. In the Introductory Activity, students explore different ways in which human actions have helped and hindered salmon populations, including efforts to artificially produce and raise salmon. In Learning Activity 1, students learn about challenges salmon face after being released from hatcheries into the wild, as well as efforts that humans are taking to restore streams and salmon runs. In Learning Activity 2, students explore issues surrounding dams and conduct research on specific dams in the US northwest. In the Culminating Activity, students review information presented in the lesson and debate the merits of human efforts to save salmon. Students write a critical essay about human impact on salmon and propose ideas for future actions. Students discuss their projects with the class.

SUBJECT MATTER: Science

Learning Objectives:

Students will be able to:

• Describe why humans are artificially producing salmon and then releasing them into the wild.
• Discuss at least four actions that humans have taken that have impacted salmon populations. Describe positive and/or negative impacts these actions have had on salmon.
• Describe the role of hatcheries.
• Describe obstacles salmon face in nature.
• Explain the issues surrounding dams and how dams impact salmon populations.
• Provide details about one specific dam and issues surrounding it.
• Describe efforts that humans are taking to restore streams and salmon runs.

STANDARDS

National Science Education Standards

Grades 9-12:

Content Standard C: Life Science

Fundamental concepts and principles that underlie this standard include:

• Biological Evolution
  • Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuing selection by the environment of those offspring better able to survive and leave offspring.
  • The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.
  • Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.
• The Interdependence of Organisms
  • Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
  • Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms.
  • Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.
• The Behavior Of Organisms
  • Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.
  • Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles.

Content Standard E: Science and Technology

Fundamental concepts and principles that underlie this standard include:

• Understandings about Science and Technology
  • Science often advances with the introduction of new technologies. Solving technological problems often results in new scientific knowledge. New technologies often extend the current levels of scientific understanding and introduce new areas of research.
  • Creativity, imagination, and a good knowledge base are all required in the work of science and engineering.
  • Science and technology are pursued for different purposes. Scientific inquiry is driven by the desire to understand the natural world, and technological design is driven by the need to meet human needs and solve human problems. Technology, by its nature, has a more direct effect on society than science because its purpose is to solve human problems, help humans adapt, and fulfill human aspirations. Technological solutions may create new problems. Science, by its nature, answers questions that may or may not directly influence humans. Sometimes scientific advances challenge people’s beliefs and practical explanations concerning various aspects of the world.

Content Standard F: Science in Personal and Social Perspectives and Technology

Fundamental concepts and principles that underlie this standard include:

• Natural Resources
  • Human populations use resources in the environment in order to maintain and improve their existence. Natural resources have been and will continue to be used to maintain human populations.
  • The earth does not have infinite resources; increasing human consumption places severe stress on the natural processes that renew some resources, and it depletes those resources that cannot be renewed.
  • Humans use many natural systems as resources. Natural systems have the capacity to reuse waste, but that capacity is limited. Natural systems can change to an extent that exceeds the limits of organisms to adapt naturally or humans to adapt technologically.

• Science and Technology in Local, National, and Global Challenges
  • Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.

MEDIA COMPONENTS

Nature: “Salmon: Running the Gauntlet,” selected segments

Access the video segments for this lesson at the Video Segments Page.

Clip 1: “Producing Salmon”

A look at how humans are producing salmon in an effort to protect the species.

Clip 2: “Humans and Salmon”

An overview of how humans have impacted salmon populations for more than 150 years.

Clip 3: “Salmon’s Journey”

An overview of salmon’s journey after being released from the hatcheries into the wild.

Clip 4: “Restoring Streams”

A look at efforts to remove dams and restore streams and salmon runs.

Websites:

Bonneville Lock and Dam

This page on the US Army Corps of Engineers, Portland District website provides information about the Bonneville Lock and Dam and includes links to Bonneville Dam Fish Ladder Camera Views at the Oregon Shore and Washington Shore Counting Stations, featuring live images, updated every few seconds, of fish passing through the counting windows.

Dam Breaching and the Lower Snake River Dams

This fact sheet, created by the Bonneville Power Administration, provides information about the estimated costs and impact of breaching (removing the earthen portion of) the four Lower Snake River Dams.

Hatcheries and Dams of the Pacific Northwest

This page on the Nature website features a map of major hatcheries and dams in the Pacific Northwest, as well as the approximate spawning grounds for each salmon species.

Large Dams in the Western United States

This website provides information about the positive and negative effects of dams and specifically highlights the Glen Canyon Dam on the Colorado River and the Bonneville Dam on the Columbia River.

Save Our Wild Salmon

This website provides information about maintaining and restoring wild salmon populations. The following pages could be used in this lesson:

• Myths and Facts about Lower Snake River Dam Removal

• Why remove the 4 Lower Snake River Dams?

Snake River Dam Operation

This website provides information about the Snake River Dams.

The Dam Challenge (Optional)

This online activity, which is used in the optional activity in Learning Activity 2, challenges users to consider different scenarios where dams exist and to choose whether to repair the dam, keep the dam as is or remove it.

MATERIALS

For the class:

• Computers with internet access.
• Computer, projection screen and speakers (for class viewing of online/downloaded video segments).

PREP FOR TEACHERS

Prior to teaching this lesson, you will need to:

Preview all of the video segments and websites used in the lesson.

Download the video clips used in the lesson to your classroom computer(s) or prepare to watch them using your classroom’s internet connection.

Bookmark any websites that you plan to use in the lesson on each computer in your classroom. Using a social bookmarking tool such as del.icio.us or diigo (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.

Proceed to Lesson Activities