Weekly Online Lesson Online Lesson Archive Grade Level: 6-8 Subject: Marine Science

A Threat to Sharks

On June 7, 2000, the House of Representatives passed a measure that would prohibit the lucrative practice of shark finning in U.S. coastal waters. Shark finning means catching and cutting off the fins of sharks, then throwing the carcass—which is worth very little—back into the ocean. The bill would make it illegal to land or possess shark fins without the carcass in U.S. federal waters, which extend out 200 miles from American territories.

The stringy tendrils from the dorsal, pectoral and lower tail fins of sharks are prized as the key ingredient of oriental shark-fin soup. Shark fins can be worth $18 to $70 a pound, depending on the size and type. By comparison, tuna sells for $3 to $5 per pound.

Most sharks are slow-growing and slow to reproduce. When they do reproduce, they have a very small number of young. These characteristics make sharks susceptible to over-fishing.

In 1993 the Commerce Department halted finning in Atlantic, Caribbean and Gulf of Mexico waters after it became apparent that the practice was affecting shark populations. But finning has continued in the western and central Pacific, particularly off Hawaii, where finning was less prevalent a decade ago and the effects on blue shark are disputed.

Responding to environmental concerns about the impact of finning on shark populations, Thai Airways announced the removal of shark fin soup from its menu. The airline said other dishes would be served which are equally delicious and pose no threat to the environment.

In this weeks online lesson you will learn more about sharks and marine ecology.

Ichthyology

Ichthyology is the study of fish. You can learn a lot about fish by visiting the Florida Museum of Natural History Ichthyology Web site. Since this lesson is about sharks, go right to the Sharks site. There's a lot here, but start with the Education page and select from the menu of topics.

Why not start with the basics? Click the first link: Learn about the different groups of Fishes. Sharks and rays belong to the class Chondrichthyes, which means "cartilaginous fishes". Their skeletons are made of cartilage, not bones. What are some of the differences between rays and sharks? What are some of the differences between Chondrichthyes and other classes of fish?

Next learn the anatomy of fish and sharks and how sharks swim. Check the Glossary of terms if you get stuck on any difficult words.

If you're ready to see some great shark photos, go to the Images search page and enter "shark" in the Common Name box. Click Query Database. What you will see is a thumbnail list of all shark images in the gallery; double-click to see the larger photo.

Sharks at SeaWorld

Learn more about sharks at SeaWorld's Sharks and Their Relatives site. You've already learned about their physical characteristics. (add)

What do sharks eat? Most eat just about anything, including other sharks. Find out more at the Diet and Eating Habits page. How long do sharks live? Find out by clicking Longevity and Causes of Death. This information relates directly to the topic of shark finning. Because sharks are slow growing, depleted populations due to over fishing may take years to recover.

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