Quantcast
Animals
A large female Greenland shark observed near the community of Arctic Bay, Nunavut. Brynn Devine

Caught on Camera: Ancient Greenland Sharks

By Brynn Devine and Jonathan A. D. Fisher

The Greenland shark is one of the world's largest marine species, reaching lengths over six meters (approximately 20 feet). And yet these fish, which prefer the deep, cold waters of the Arctic and North Atlantic oceans, have largely eluded scientific study.

Their evasiveness highlights how little we know about Arctic marine ecosystems—and how much we can learn by developing and employing new technologies.


For scientists like us, the observation and monitoring of marine species can be challenging under the best of circumstances. But sampling at extreme depths and in seasonally ice-covered waters is especially difficult.

Researchers Brynn Devine (right) and Laura Wheeland aboard the vessel Kiviuq I off the community of Grise Fiord on southern Ellesmere Island in 2016 Laura Wheeland, author provided

However, we recently captured some of the first underwater video footage of Greenland sharks in the Canadian Arctic. The recordings gave us valuable insight into their abundance, size and behavior, as well as their distribution in the Canadian Arctic.

These findings are the first step towards closing a major knowledge gap on the population status of the Greenland shark.

And we did it without taking any sharks from the water.

Sleeper Sharks Revealed

Until now, most of what we knew about Greenland sharks came from the historical records of commercial landings. They were fished in the North Atlantic for their oily livers until 1960. A limited harvest still occurs in Greenland, and the species is sometimes encountered as bycatch in fisheries that occur within its geographical range.

But in areas of the North Atlantic and Arctic where commercial fishing has not historically occurred—such as the waters of the Canadian Arctic Archipelago—their full geographic range has remained unknown.

Due to their sluggish and seemingly lethargic behavior, the Greenland shark is part of the family of "sleeper sharks." Despite being remarkably slow swimmers and effectively blind, thanks to eye parasites, the Greenland shark is one of the Arctic's top predators.

A small Greenland shark, less than 1.5 meters long, observed inside Scott Inlet on northern Baffin Island Brynn Devine, author provided

Although they feed mostly on a diverse buffet of bottom-dwelling fishes, there is some evidence that they can capture live seals. Just how they catch these fast-swimming marine mammals remains a mystery to researchers.

Greenland sharks are by far the largest fish in the Arctic. They rival the great white shark in length, if not its fear factor.

Scientists have also puzzled over their life span and growth rates. They appear to grow extremely slowly—less than one centimeter per year—and are believed to not reach maturity until females are 4.5 meters (approximately 14.7 feet) long and males are three meters (approximately 9.8 feet) long.

They also have remarkable lifespans. Scientists recently used radiocarbon dating techniques on the eye lens of a Greenland shark, and found they can live for more than 272 years, making the species the longest living vertebrate on the planet.

While these are impressive traits, their age and large size leave Greenland sharks more vulnerable to stressors such as overfishing or habitat loss than other fishes.

Candid Camera

Scientists know little about Greenland sharks living in the unfished waters of the eastern Canadian Arctic. To help collect information on sharks residing in this region, we baited cameras with squid and dropped them into the deep waters of Nunavut.

After two summer field seasons, we had more than 250 hours of high-resolution video recorded from 31 locations.

Greenland sharks arrived at 80 percent of our deployments. We used the video to distinguish one individual from the next based on their unique skin markings, a method researchers also use to identify for whale sharks and great white sharks. Altogether, we identified 142 individual sharks.

The videos also gave us additional information about the sharks, including their length and swimming speeds. In some locations, the sharks were relatively small—less than 1.5 meters (approximately 4.9 feet) long—in others, they were over three meters long, but nearly all of them were likely still too young to reproduce.

Researchers are increasingly using video to survey marine wildlife. Baited-camera surveys eliminate the adverse effects of scientific longline surveys, where fish are caught on hooks. Even though the sharks are later released, many suffer from the stress of capture or can become entangled in the fishing gear, which can lead to death.

New Information for a Changing Arctic

We did most of this work within the region of Tallurutiup Imanga (Lancaster Sound), which could become Canada's largest marine protected area.

This area is known as a vital feeding and nursery ground for many Arctic species of both ecological and Inuit cultural significance, including whales, seabirds, polar bears, seals and walruses. Our video data now shows that this area might of be important to Greenland sharks too, at least in summer months.

Map of baited camera deployments where Greenland sharks were observed, with symbol sizes proportional to the number of individuals distinguished from each set. The 'X' indicates sets where no sharks were observed.http://www.nature.com/articles/s41598-017-19115-x, CC BY

In addition, given the significance of top predators in controlling the dynamics of high latitude marine ecosystems, the role of Greenland sharks may represent an important link in Arctic food webs.

At a time when oceans are rapidly warming, Arctic sea-ice cover is shrinking and there is increasing interest in Arctic fisheries and conservation, it's important that we understand the domains of these large, ancient creatures.

Reposted with permission from our media associate The Conversation.

Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Adventure
Háifoss waterfall is situated near the volcano Hekla in the south of Iceland. FEBRUARY / Getty Images

The Essential Guide to Eco-Friendly Travel

By Meredith Rosenberg

Between gas-guzzling flights, high-pollution cruise ships and energy-consuming hotels, travel takes a huge toll on the environment. Whether for business or vacation, for many people it's not realistic to simply stop traveling. So what's the solution? There are actually numerous ways to become more eco-conscious while traveling, which can be implemented with these expert tips.

Keep reading... Show less
Popular
Westend61 / Getty Images

EcoWatch Gratitude Photo Contest: Submit Now!

EcoWatch is pleased to announce its first photo contest! Show us what in nature you are most thankful for this Thanksgiving. Whether you have a love for oceans, animals, or parks, we want to see your best photos that capture what you love about this planet.

Keep reading... Show less
Animals
Freder / E+ / Getty Images

Surprising Study: Orangutans Are Only Non-Human Primates Who Can 'Talk' About the Past

We already know that orangutans are some of the smartest land animals on Earth. Now, researchers have found evidence that these amazing apes can communicate about past events—the first time this trait has been observed in a non-human primate.

A new study published in the journal Science Advances revealed that when wild Sumatran orangutan mothers spotted a predator, they suppressed their alarm calls to others until the threat was no longer there.

Keep reading... Show less
Health
Suicide rates are highest for males in construction and extraction; females in arts, design, entertainment, sports and media, the CDC found. Michelllaurence / Flickr / CC BY 2.0

CDC: Suicide Rate Among U.S. Workers Increasing

From 2000 to 2016, the suicide rate among American workers has increased 34 percent, up 12.9 per 100,000 working persons to 17.3, according to a worrisome new study from the Centers for Disease Control and Prevention (CDC).

Workers with the highest suicide rates have construction, mining and drilling jobs, the U.S. health officials reported Thursday.

Keep reading... Show less
Sponsored
Energy
PG&E received a maximum sentence for the 2010 San Bruno natural gas pipeline explosion. Wikimedia Commons / CC BY-SA 3.0

Report: 90% of Pipeline Blasts Draw No Financial Penalties

A striking report has revealed that 90 percent of the 137 interstate pipeline fires or explosions since 2010 have drawn no financial penalties for the companies responsible.

The article from E&E News reporter Mike Soraghan underscores the federal Pipelines and Hazardous Materials Safety Administration's (PHMSA) weak authority over the fossil fuel industry for these disasters.

Keep reading... Show less
Politics
Nevada Test and Training Range. U.S. Air Force / Airman 1st Class Kevin Tanenbaum

U.S. Navy Proposes Massive Land Grab to Test Bombs

Friday the U.S. Navy released details of a plan to seize more than 600,000 acres of public land in central Nevada to expand a bombing range. The land under threat includes rich habitat for mule deer, important desert springs and nesting sites for raptors like golden eagles.

Keep reading... Show less
Sponsored
Climate
A deer stands in the remains of a home destroyed by the Camp Fire. JOSH EDELSON / AFP / Getty Images

63 Dead, 631 Missing in Deadliest, Most Destructive Fire in California History

The death toll from the catastrophic Camp Fire—by far the deadliest and most destructive fire in California history—has now risen to 63, with 631 people still unaccounted for, the Huffington Post reported Friday.

The Butte County Sheriff's Office announced on Thursday that the death toll had risen from Wednesday's figure of 56 after the remains of seven more people were discovered in the wreckage.

Keep reading... Show less
Health
A smoky haze obstructs the view of the San Francisco skyline on Aug. 24 in San Francisco, California. Justin Sullivan / Getty Images

Smoke Is a Big Health Risk as California Wildfires Rage On

By Nneka Leiba

Deadly wildfires continue to blaze in Northern and Southern California. Dozens of people are dead, hundreds more missing and entire communities have been destroyed.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!