Case Study: Kemp's Ridley Sea Turtles
Cause and Effect
Overview:
Students will sequence the events leading to Kemp’s Ridley sea turtles being placed on the endangered species list and current conservation efforts.Objectives:
The students will be able to…- …understand that human activity affects wildlife populations and habitats.
- …relate current conservation efforts to the scientific method.
Materials:
- Research materials on Kemp’s Ridley sea turtles
Procedure:
- Create event cards using the table below and mix them up randomly.
- Have students place the event cards in chronological order. You may choose to let them research the topic first, or use this as an introductory activity.
- After the events are correctly sequenced, correlate the observations, research, and current conservation efforts to the scientific method. Which cards recognize a problem? Which cards show research? Which cards show an experimental study and the results? Which cards show conclusions and actions based on research? Which cards show a need for further study?
Extensions:
- Research in-depth and debate the international trade implications associated with the import of shrimp from foreign countries and sea turtles protection laws.
Sequence Cards:
| Event | Timeframe |
|---|---|
| Kemp’s Ridley are abundant in the Gulf of Mexico, with over 40,000 female turtles coming to shore to nest. They each lay approximately 100 eggs per nest. Their only nesting site is Rancho Nuevo, Mexico | Late 1940s |
| Sea turtle eggs and turtle meat are considered delicacies and are in high demand. Many turtle eggs are taken from nests and turtles are taken for their meat. | 1940s—1950s |
| The number of Kemp’s Ridley sea turtles nesting in Rancho Nuevo significantly decreases. Less than 1,000 nests are observed. | 1950s—Present |
| The Kemp’s Ridley sea turtle is placed on the endangered species list. It is considered the most endangered sea turtle in the world. | 1970 |
| Shrimp becomes a popular food and shrimping increases in the Gulf of Mexico. | 1970s—1980s |
| Shrimp nets can be perilous to animals that breather oxygen, such as marine mammals and sea turtles, as the animals can become tangled and drown. After researching the population decline in sea turtles, shrimp trawlers were named as one of the main causes of sea turtle mortality. | 1970s—1980s |
| Scientists and engineers develop a Turtle Excluder Device (TED) that can be used on shrimp trawl nets to allow larger animals to escape. | Mid-1980s |
| The Mexican government names Rancho Nuevo a protected beach. They prohibit the harvesting of Kemp’s Ridley eggs and sea turtles. Fishing is prohibited off the Rancho Nuevo beach during nesting season. | Late 1960s—Early 1970s |
| The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) prohibits trade in turtle products, striving to protect them from slaughter for jewelry, accessories, and decorative items. | 1973 |
| The US and Mexican government partner in an attempt to create a second nesting beach. Eggs are taken from Rancho Nuevo to Padre Island, Texas and are allowed to hatch. The baby turtles are “imprinted” to the beach as they make their way to the surf. Baby turtles are then taken to a research facility where they are protected during their early stages of life. This is known as “head-starting.” They are released back into the Gulf of Mexico when they are about 11 months old. | 1978—present |
| Kemp’s Ridley nests begin to be seen on Padre Island. | 1996—present |
| Turtle Excluder Devices (TED’s) are required on domestic shrimp trawls. When used correctly, these devices reduce the mortality rate of sea turtles by shrimp trawlers up to 97%. | Late 1980s |
| Congress passes a complementary law to the Endangered Species Act that bans the import of shrimp from countries in the Western Hemisphere that do not have comprehensive sea turtle protection policies, such as Turtle Excluder Devices (TED’s) being required on all shrimp trawls. This law is later expanded to include all nations. This is a topic of debate as many countries feel this violates international trade agreements. The World Trade Organization (WTO) has tried to help settle this debate between the US and other countries for many years. The US has had to modify this law. | 1989 |
| The National Wildlife Federation is instrumental in winning Senate ratification of the Inter-American Convention for the Protection and Conservation of Sea Turtles, the first regional agreement to protect sea turtles and their habitats from many of the threats they face. | 2000 |
| Kemp’s Ridley appears to slowly be rebounding. Approximately 7,000 nesting sites have been observed. | 2003 |
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