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Sharks
Taking a Bite Out of the Myth

Written by: Laura Rose, Virginia Sea Grant, Virginia Institute of Marine Science

Grade Level:
9-12

Lesson Time:
45 min - 1 hr.

Materials Required:
Graphing paper ruler OR Excel

Natl. Science Standards
Click here for a list of the aligned National Science Education Standards.

Related Resources
Sharks, Skates & Rays, Fisheries, Policy & Resource Management

Summary
Explore trends in shark populations using shark landing data from the National Marine Fisheries Service.

Objectives

  • Recognize the low risk of shark attack compared to other hazards.
  • Discuss the impact of fishing on sharks as long-lived, slow-growing species.
  • Evaluate shark population numbers using shark landing data.
  • Discuss trends in shark data and the impact of management efforts.

Vocabulary
Acoustic telemetry

Introduction
What are your chances of being struck by lightning? They're not as slim as winning the lottery, but they're a lot greater than being attacked by a shark. That simple five-letter word is capable of sending shivers down spines, raising heartbeats, and turning otherwise rational people into paranoid land-lubbers. The truth is, more people are killed in the U.S. each year by dogs than have been killed by white sharks in the last 100 years. For some interesting statistics, visit the International Shark Attack File.

Get to know the shark, and you'll find that, contrary to popular belief, it is not a vicious feeding machine with a hankering for humans. Like many other predators in the Animal Kingdom, it hunts when it's hungry, and it attacks when it feels threatened. There are almost 400 species of sharks, and there is much to appreciate about these graceful and powerful creatures. The shark's body design and its amazing senses are marvelous gifts from Mother Nature. Get beyond the Hollywood myths about the shark, and learn about this awesome animal which plays a vital role in the ocean ecosystem.

Sharks fascinate us, perhaps because they're on top of the food chain, and they're called the "perfect predator". They're indestructible. Or are they? There is much concern now over their dwindling numbers. On average, sharks don't reach sexual maturity until they're seven years old, and a female will bear less than a hundred pups in her lifetime. These characteristics make it difficult for shark populations to keep up with commercial fishing pressure.

Data Activity
In April of 1993, the National Marine Fisheries Service implemented regulations that established a federal management program for 39 shark species in the Atlantic, Gulf of Mexico and Caribbean. Let's graph the annual landings of some of these shark species by using the Commercial Fisheries data compiled by the National Marine Fisheries Service Statistics and Economics Division. Input the following in the form:

  • Species: enter "shark, tiger", "shark,mako unc" (no space before mako), "shark, longfin mako", "shark, sandbar", "shark, blacktip", or "shark, dusky" (for a list of other shark species in the database, enter "shark" in the SpeciesLocator)
  • Year Range: 1988-1998
  • State/Area: Atlantic and Gulf
  • Output Form: Table

Click here for step by step instructions on graphing in Microsoft Excel.

What can you infer from these data? Are there trends evident in the years before and after the implementation of the federal management program?

Repeat the exercise by extending the Year Range to the most recent available (Latest Year). How do the trends change over the extended period of time? Why?

In an effort to find an alternative to the periodic tiger shark elimination campaigns in Hawaii, a group of researchers submitted a proposal to study the sharks and try to gain a better understanding of their behavior. Two main goals are determining movement patterns and habitat use of these predators. The Tiger Shark Research Program uses tags and acoustic telemetry to follow individual sharks. Some of their results suggest that tiger sharks have extremely large home ranges and that control programs are unlikely to be effective in catching sharks responsible for attacks as these individuals may move beyond the fished area within hours of the incident.

 The Bridge is sponsored by NOAA Sea Grant and the National Marine Educators Association

Virginia Sea Grant Marine Advisory Program
Virginia Institute of Marine Science
College of William and Mary