Showing posts with label shark attack. Show all posts
Showing posts with label shark attack. Show all posts

Saturday, 4 October 2014

WHAT DO TIGER SHARKS EAT?







Tiger Sharks have a bad reputation and are second only to the Great White Sharks in attacking humans.



Tiger sharks teeth are serrated with powerful jaws making them an ideal killing machine. They are able to bite through the shells of sea turtles.

Tiger Sharks will eat almost anything but dolphins are a favorite food. Studies have shown that 70% of wild dolphins have scars from shark bites (mostly as calves).

In Sand Tiger Sharks, the biggest, strongest pups eat their brothers and sisters while still inside their mother’s body. This seems terrible but guarantees the birth of the most aggressive young.



A Tiger Shark’s teeth are not attached to the jaw, but grow in their flesh. In order to keep the biting equipment in order, teeth are constantly replaced throughout the shark's life.


In 1935, an Australian Tiger Shark spat out a human arm. Police discovered that the shark had not attacked anyone but had eaten the arm after a murder victim had been cut up and thrown into sea.






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Sunday, 9 February 2014

The Disappearing Sharks









My interest in sharks was like everyone’s – morbid. A shark attack with photos was front page news and each sparked debate in the dive clubs over the best way to avoid becoming the next victim. I sometimes carried a ‘bang stick’ so I could fight these villains if it came to the worst.

When I started work on the Great Barrier Reef , I got a surprise. The sharks seemed bigger, more numerous, and very brave compared to their Caribbean brothers. Australian shark attacks were front page stories and dominated the news for days.




And yet there I was working for hours every day, year after year within metres of these predators and all I had to do to avoid trouble with the tropical species was respect their territories and not swim around with speared fish on my belt.



So how real is the case against sharks?
 Every year about 100 shark attacks are reported worldwide. In 2011,  just 17 fatalities were recorded as having being caused by sharks, out of 118 attacks.  Although shark attacks are infrequent, there is a heightened awareness due to occasional serial attacks; “it’s out there and it’s after me”. Horror fiction like Jaws appears on TV just often enough to keep this fear alive and even “nature” shows only show sharks in frenzied feeding.



Shark attack experts are adamant that the danger has been greatly exaggerated. According to the International Shark Attack File (ISAF), between the years 1580 and 2011 there were 2,463 confirmed unprovoked shark attacks around the world, of which 471 were fatal. Surprisingly, that’s only 1.09 fatalities per year for the last 431 years.
Australia is ranked second in terms of global shark attacks with 877 attacks since colonial settlement in the 18th century; it’s ranked the highest in terms of shark fatalities, with only 217 during this long period.
The results of Gore’s Michigan State University study reviewing worldwide media coverage of sharks found that more than 52 percent of global coverage focused on attacks on people and sharks were portrayed as aggressive and dangerous in nearly 60 percent of the reports. Positive PR was tougher to find with only 10 percent of stories dealing with shark conservation and just 7 percent looking at biology and ecology.
According to Time/ CNN : Zoologists today estimate elephants around the world kill 500 people a year while the great white sharks (Jaws)  kill only 4 people.

Incredibly, there are about 24,000 lightning deaths (one every 20 minutes) and 240,000 injuries worldwide annually (Royal Aeronautical Society, 2003). When was the last time we read stories of the lurking danger above or watched a movie where people were struck down like dominoes by searing thunder bolts?

Why is shark conservation so important and why is it being neglected?

The first part of this question is easy. Sharks are in big trouble. "Overfishing of sharks is now recognized as a major global conservation concern, with increasing numbers of shark species added to the International Union for the Conservation of Nature's list of threatened species," say Mizue Hisano, Professor Sean Connolly and Dr William Robbins from the ARC Centre of Excellence for Coral Reef Studies and James Cook University.
 Why we are neglecting shark conservation is harder to answer. First, there have been powerful economic reasons to turn a blind eye to shark fishing and shark finning. These may not have been good reasons but greed is a characteristic of human behaviour and we make lots of poor decisions because of it.





A second explanation comes from deep in the primitive part of our brains. Our prehistoric ancestors had the very same fears that we do according to Psychology Today. We were ‘designed’ to be afraid; fear was our operating manual for things we didn’t understand or that could do us harm. Fears protected our ancestors. “Our distant ancestors who were afraid of heights didn’t fall off cliffs, those that feared wild animals didn’t get eaten, those that ran the fastest left the rest behind---and they survived.” 

 Elephants are not on our list of feared animals and we donate millions of dollars each year to protect them even though they kill thirty times more people than sharks. Why can’t we see that the health of our ocean hangs in the balance and that we are making decisions with our ancestor’s fears and not with our future in mind?

Special thanks to my friends Ellen Cuylaerts and Shawn Heinrichs whose photos 'tell' the story.







Tuesday, 9 July 2013

SWIMMING WITH TIGERS by Dr. "Gerald Goeden"


There is much concern about shark fishing and shark fining. Ocean conservation is at stake as predators in all the world oceans are subjected to over-fishing. Caribbean and Andaman Sea fisheries (Malaysia) are especially stressed. Growing support for eco-tourism based experiences like swimming with sharks and swimming with dolphins promise to outstrip the economic benefit of over-exploitation. The following report looks at the experience of one of our scuba divers in assessing a shark conservation project off South Africa.

During a recent photo expedition Jeff had a surprise visit from a big Tiger Shark. Jeff and Gerry tell the story:

“All of a sudden something was holding on to my scuba gear and shaking me like a feather. I was so busy getting some great shots that I didn’t see this big one come up behind me.”



“I was pretty lucky that I wasn’t hurt, but it seemed like the Tiger was just trying to figure out what I was.”

The Tiger Shark, which generally hunts at night, has a reputation for eating anything and everything and for an aggressive nature. Most of the time, Tiger Sharks eat fish, squid, seabirds, sea mammals, other sharks, and turtles.

Out of more than 360 shark species, only four have been involved in a significant number of fatal attacks on humans over the last 60-70 years: the great white, tiger, oceanic white tip, and the bull shark. Culling Tiger Sharks a few days after an attack probably has little value since most are nomadic and the offending animal may well move on. Some governments ‘protect’ swimming beaches with shark nets that catch any sharks swimming along the coast.

Even small Tiger Sharks require a lot of watching and big ones can weigh up to 1000 kg and reach 6-7.5 metres. They get the name Tiger from the vertical stripes and not from their diet. Based on diet, they are more like ‘trash-can sharks’ since stomachs have been found to contain buckets, rolls of wire, gas cans, paint brushes, and baseballs. One even contained old tires.

So why did the shark bite Jeff’s metal air tank?

First, the shark was confused by the metal on Jeff’s back. Tiger sharks have small pits (ampullae of lorenzini) on their snout and along their upper bodies which can sense weak electrical fields. Normally these sensors detect fish when the water is too murky for their usually sharp eyes to see. But different kinds of metals generate weak electric currents in seawater and alert the shark that something is going on.



Secondly, the Tiger Shark’s keen sense of smell would not be sure if the smell of human meant the next meal or danger. You don’t grow up to be a big shark without a little caution!

Finally, sharks adopt the same strategy as children; if you are unsure what something is, just put it in your mouth and taste it.

“Diving with Tiger Sharks is awesome and something I will never forget. The footage will be great for documentary work and we always learn something about these incredible animals. We have to work fast as Tiger Sharks are disappearing because of the shark fin trade and sport fishing.”



Nature has equipped these sharks with all the gear to be great hunters: they can sense movement in the dark, feel water pressure waves from injured animals, smell traces of blood in the water, and have excellent vision. They are fearless and haven’t learned to stay away from boats and fishing gear.

“Our strategy is to stay close to the bottom and keep our movements slow and steady. We have to be careful not to brush against them because their skin is like sharp sand-paper and could leave you bleeding. I will also say that paying attention to what’s coming up behind you has to go to the top of my list.”

 
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