Canada and the World
Current Events with a Canadian Perspective
Last update
21 November 2011
Mistreatment of Sharks
Top predators such as sharks are vital to the
health of marine ecosystems but they are
being hunted and killed close to extinction
Sharks are in need of an image make-
In fact, the danger is the other way round; humans are destroying an animal that regulates life in the oceans.
Ed Garcia
Photoshopping such as this might help us feel better about sharks.
Grossly Distorted Media View of Sharks
Mention the word shark, especially to someone swimming in warm tropical water, and the reaction will be rapid and dramatic.
But, the person heading for the beach faster than you can say “Jaws” is operating on false information.
Sharks are not very interested in people as a lunch item. As far as sharks are concerned humans are the menu equivalent of overcooked Brussels sprouts.
The Canadian Shark Research Laboratory (CSRL) points out that, “Of the more than 350 species of shark in the world’s oceans only a handful of them are even considered dangerous to humans…Overall, the chance of being attacked by a shark is considerably less than that of being hit by lightning or of being eaten by a crocodile.”
In July 2008, John Tierney of The New York Times reported that, “Throughout the world last year, there was a grand total of one fatal shark attack (in the South Pacific)…”
By contrast, in October 2006 National Geographic’s Nicholas Bakalar covered a study carried out by the United Kingdom’s Imperial College London: “…researchers concluded that from 1996 to 2000, 26 to 73 million sharks were traded yearly. The annual median for the period was 38 million.” Obviously, if traded, the animals were dead.
Shark-
There’s a blood-
It’s not the depiction of a swimmer being bitten in half by a great white. It’s not even a shot of a feeding frenzy as a dead seal is tossed into the ocean.
It’s the sight of a shark being hauled onto the deck of a fishing vessel, having its fins hacked away, and then being thrown back into the water still alive.
What happens next is described by the environmental group Stop Shark Finning: “The
sharks either starve to death, are eaten alive by other fish, or drown (if they are
not in constant movement their gills cannot extract oxygen from the water). Shark
fins are being ‘harvested’ in ever greater numbers to feed the growing demand for
shark-
Decimation of Shark Population
In June 2009, Bloomberg News reported that “Great whites, hammerheads, and a third
of deep-
Twenty species were threatened in 2009; that’s an increase of four over the previous year.
The folks at the Save our Seas Foundation offer the following figures: “It is estimated
that 96.1% of all threats posed to shark populations stem from fishing (57.9% by-
Top Predator in a Complex System
Perhaps the most important characteristic of sharks is that they are what’s called “top predators.” Their position in the marine food web is vital to the health of the entire system.
“Big fish eat little fish; that’s how the food cycle works. Of course, there’s more to it than that.” That’s the way Tony Corey with Dave Beutel describe the balance in The Marine Food Web in which it’s explained that each level in the food chain, from phytoplankton to top predators, is intimately dependent on the other levels.
Remove one level from the chain and the whole structure is threatened.
Effect of Losing Sharks
While studying the effect of species loss in oceans is difficult some information is known.
Ransom Myers and colleagues published a paper in Science in March 2007 covering a loss of sharks off the coast of North Carolina.
The blacktip sharks were overfished so much that there was a population explosion among the rays on which they fed.
The numerous rays preyed on scallops and reduced their numbers so dramatically that the commercial fishery collapsed. The scallop fishery may never recover, destroying the livelihoods of local people.
Fishers in other areas of the world have reported a large increase in seals, a favourite food for sharks. The seals feed on herring, cod, flounder, and many others species that sustain commercial fisheries.
Without sharks to keep the number of seals under control humans will lose an important food source.
Sources
“10 things to Scratch from your Worry List.” John Tierney, New York Times, July 29, 2008.
“38 Million Sharks Killed for Fins Annually, Experts Estimate.” Nicholas Bakalar, National Geographic, October 12, 2006.
“Shark-
“The Marine Food Web.” Tony Corey with Dave Beutel, Sea Grant, undated.
“All Hail Toronto’s Shark Fin Ban.” Globe and Mail, October 27, 2011.
© Canada and the World, November 2011
All rights reserved
According to the Canadian Shark Research Laboratory, “Only 19 shark species reside in Canadian Atlantic waters, five of which are considered to be occasional visitors. The remaining 14 species are seen with some regularity.”
LACK OF INFORMATION
The role of top predators in a land ecosystem is fairly well understood.
For example, wolves disappeared from the Yellowstone National Park in the United States in the 1940s. As a result, there was an increase in the park’s elk population that the wolves had fed on.
The uncontrolled elk numbers led to overgrazing that devastated habitats destroying the food sources for many other species lower down the chain.
In 1995, wolves from Canada were reintroduced to the park; they have thrived and brought a more natural balance back to the environment.
The cascading effect of losing the top predator in Yellowstone was easy to study, but just try researching the same process in millions of square kilometres of open ocean.
As they point out at Save Our Oceans: “So much of our understanding of the top-
In other words, educated guesswork.
The Globe and Mail reports that Shark-
In November 2011, Reuters News Agency reported that the European Union is proposing a ban on sharking finning.