(K'JIPUKTUK) HALIFAX - Sharks have survived five great extinctions on this planet, patrolling the high seas since the time of the dinosaurs. They're the oldest predators in the ocean, but now they're falling victim to one of the youngest.
A paper published by renowned marine biologist Ransom A Myers in 2003 brought international attention to the recent and dramatic declines in shark populations. The work of Myers and his team was based on research in the northwest Atlantic Ocean - the east coasts of Canada and the United States.
"We had data from 1986 to about 2000," said marine conservation biologist Boris Worm, who co-authored the 2003 paper. "[We] saw these large 50-90 per cent declines [in shark populations] over that 15 year period. It was clear those trajectories would pose some species with the threat of extinction in the near future."
Subsequent research confirmed this issue was not isolated to the northwest Atlantic, but was in fact occurring in many of the world's oceans. Sharks were fast disappearing.
The findings of this study compelled Worm to become outspoken on shark conservation over the last decade. He continues to research their dwindling populations and voice his concern over causes of shark mortality.
"The main concern here is by-catch mortality," said Worm. "[Shark] species are caught inadvertently [in fishing nets]. There's no market for them so they're thrown back, but maybe one in three of them dies due to injuries sustained as by-catch. That happens a lot, so that's a real concern."
Worm has been working with fishermen to reduce shark by-catch, but in the case of longline fishing, it has proven difficult. Longline fishing is when a lengthy line is fed into the water with hundreds of baited hooks along its length. Worm said even fishermen skilled at avoiding by-catch have pulled in longlines with dozens or hundreds of sharks hanging off them. Now he's trying to determine where and when shark by-catch is most frequent so these incidents can be avoided.
"By-catch is a problem not just for the sharks," said Worm. "It's also a problem for fishermen, because it takes their bait away. It takes time to disentangle and take the sharks off the line. [Fishermen] incur some costs that are not good from a profit perspective and not good from an ecological prospective."
Another threat is the practice of "finning." This is when a shark is caught, its fins are cut off and, in many cases, the animal is thrown back overboard to die. Fins are the most profitable part of a shark, used as an ingredient in dishes like shark fin soup or simply sold as trophies. Worm said this was the leading cause of shark mortality in their 2003 paper, but finning was banned in Canadian waters in 1994 and recently across the entire North Atlantic. He said it's still a leading cause of shark mortality elsewhere.
In a 2013 paper, Worm and his team estimated global shark mortality rates at 100 million sharks each year, despite efforts to protect them. This is significantly more than sharks can sustain.
"I don't expect people to educate themselves," said Worm. "I think actually that's the role of us scientists, to very clearly explain what sharks are and what they're not."
Explaining what they're not can be an uphill battle for some experts. Emily Dodge, a shark enthusiast with almost ten years experience as an environmental educator, said sharks are too often misunderstood by the public and media alike.
"Shark attacks are extremely rare events," said Dodge. "The media, however, generally sensationalizes such events, which gives the public the impression that shark attacks are more common than they are and that sharks are ruthless killers. There are only 10 out of 400 species of shark that have ever been implicated in attacks. In 2014 there have been 75 shark attacks, six of which have been fatal. None of the attacks have been in Atlantic Canadian waters."
Dodge said Atlantic Canada is very important habitat for sharks...and sharks are likewise important for the ecological health of Atlantic Canada. As an apex predator (top of the food chain), she said sharks keep fish stocks strong by preying on the weak or sick members of a population, even preventing the spread of disease.
Worm said the exact consequences of declines in shark populations are still uncertain, but studies in the United States offer some insight.
"Sharks act like a police, basically," said Worm. "The police don't arrest very many people, but they keep a lot of people following the rules just by being present. Sharks tend to do the same. There are large behavioural effects that sharks have by scaring species out of certain habitats and allowing those habitats to flourish, at least seasonally. So, that basically contributes to the overall health and balance of the ecosystem."
Fulfilling their mandates as educators, both Worm and Dodge are among several shark enthusiasts sharing their knowledge and experience with Halifax later this month. For the Love of Sharks is a series of educational workshops and presentations being held at Halifax's Natural History Museum, all with the common goal of bringing sharks into focus for Nova Scotians.
Worm is giving his presentation Of Sharks and People Oct 15 to kick off the event series, while Dodge is hosting children's activities Oct 24, bringing the series to a close. Other experts will fill the days between, with events scheduled for Oct 18-19.
"I always find that children, and adults, are interested in learning more about sharks," said Dodge, "because they are both a fascinating and misunderstood species. This event is a great opportunity for people of all ages to come out and learn more about sharks, and how they can get involved in helping to protect this incredible animal."
To learn more about Worm's research or sharks in the northwest Atlantic Ocean, visit atlanticsharks.org. To learn more about the upcoming For the Love of Sharks event series, or to browse the schedule, visit atlantic.sierraclub.ca/for-the-love-of-sharks.
