Sharkwater

My assignment this week was to watch the filim "Sharkwater" and answer questions about it.

Shark Myths

1. Why are sharks so hard to photograph?

They often feel threatened by humans and avoid us.

2. What prey defenses have evolved in fish in response to predators like sharks?

Schooling, camouflage, speed, size, and communication

3. What strategies are given for repelling sharks in the black and white film?

Sounds, a stream of bubbles, shredding paper to confuse the shark.

4. According to the documentary, elephants kill more people than sharks. Why then, do people fear sharks so much more?

Psychological revulsion to a "cold monster of the deep".

5. What conditions around the Galapagos Islands of Darwin and Wolf make them so favorable for the hammerhead sharks?

Undersea currents bring plankton, which attracts creatures that eat the plankton, which attracts hammerheads.

6. What two additional senses do hammerhead sharks have that humans do not?

Lateral lines and electromagnetic detection.

7. How many humans have been killed by hammerhead sharks?

Zero

Long Line Fishing

8. List the fish found in the long line recovered by the film crew.

Sailfish, Dorado, Sharks, and Tuna

9. Explain why sharks are not equipped to tear flesh from animals larger than them. What causes moast human deaths from shark attack?

A shark's teeth are not designed for tearing flesh. Most shark related deaths are caused by blood loss.

10. As illustrated by the book Moby Dick, people used to be afraid of whales. How have public perceptions of whales changed since then.

People have come to see them in a new light as beautiful.

11. What does Captain Paul Watson and the Sea Shepherd Conservation Society do to protect whales and sharks from illegal fishing?

They intervene directly to provide enforcement of fishing and whaling regulationsm and treaties, sometimes at the request of governments, sometimes on their own. They sometimes ram whaling ships..

12. The Sea Shepherd caught the Varadero I, an illegal shark fishing boat. Why didn't the fishermen stop on orders from the ship? What are shark fins used for?

The fishermen would lose their ship, their fishing license, and their profits. Shark fins are used to make shark fin soup, which is seen as a status symbol in some Asian cultures.

13. What is the basis for the belief that shark fins have medicinal properties?

Sharks appear to be more resistant to disease, though there is no scientific basis for this. Some people think eating their fins will give them the shark's power to resist disease.

14. How did the Varadero I eventiually escape? Why was the crew of Sea Shepherd arrested?

Varadero agreed to follow Sea Shepherd to port, but they called the Guatemalan authorities and lied about what happened, saying the Sea Shepherd people tried to kill them. They paid off corrupt officials. Sea Shepherd was ordered to disengage, and the crew were charged with attempted murder.

15. Upon their return to the Galapagos Islands, the crew comes across fishermen hunting sea cucumbers. One of them was badly afflicted with the bends. What causes this sickness? Why weren't they returning to shore for treratment?

The bends are caused by rapid differential in pressure: diving too deep and surfacing too quickly. The fisherman did not want to return to shore because they would lose time and money.

16. Why did fishermen want long-line fishing legalized on the Galapagos Islands?

So that they could fish for sharks.

17. Overall shark population is estimated to have declined by ____.

90%

18. Explain how a decline in top predators like sharks can affect producers like plankton.

Plankton feeders are eaten by sharks When sharks decline, the plankton feeders increase their population and eat up more of the plankton, which provide most of our oxygen..

19. As Rob Stewart returns to Costa Rica, he was concerned about being arrested or caught by the mafia. What did he discover was happening there instead? What change was brought about in part because of public pressure?

Protests against finning and in favor of conservation were happening. Public pressure made long lining in the Galapagos illegal again.-More than 100 countries have banned shark finning.

For my assignment, I also had to look up the status of several shark species featured in the film:

A. Scalloped Hammerheads (Sphyrna lewini) often gather together in large groups, which makes them easy targets for fishermen. They have a long age of maturity, which means their population will not be sustainable, because they can not replace themselves as quickly as they are being killed. They are endangered.

B. Whale shark (Rhinchodon typus) fins are highly valuble, and juveniles are easy targets. It is estimated that there is a more than 50% decline in whale shark populations worldwide. They are also classified as endangered.

C. Carcharhinus longimanus, or the oceanic whitetip shark, is a common victim of by-catch. Although their population is declining, they have not reached endangered levels yet, and are classified as vulnerable.