Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Caught on Camera: Ancient Greenland Sharks

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

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.

EcoWatch Daily Newsletter

Residents plant mangroves on the coast of West Aceh District in Indonesia on Feb. 21, 2020. Mangroves play a crucial role in stabilizing the coastline, providing protection from storms, waves and tidal erosion. Dekyon Eon / Opn Images / Barcroft Media via Getty Images

Mangroves play a vital role in capturing carbon from the atmosphere. Mangrove forests are tremendous assets in the fight to stem the climate crisis. They store more carbon than a rainforest of the same size.

Read More Show Less
UN World Oceans Day is usually an invite-only affair at the UN headquarters in New York, but this year anyone can join in by following the live stream on the UNWOD website from 10 a.m. to 5 p.m. EST. https://unworldoceansday.org/

Monday is World Oceans Day, but how can you celebrate our blue planet while social distancing?

Read More Show Less
Cryptococcus yeasts (pictured), including ones that are hybrids, can cause life-threatening infections in primarily immunocompromised people. KATERYNA KON/SCIENCE PHOTO LIBRARY / Getty Images

By Jacob L. Steenwyk and Antonis Rokas

From the mythical minotaur to the mule, creatures created from merging two or more distinct organisms – hybrids – have played defining roles in human history and culture. However, not all hybrids are as fantastic as the minotaur or as dependable as the mule; in fact, some of them cause human diseases.

Read More Show Less
National Trails Day 2020 is now titled In Solidarity, AHS Suspends Promotion of National Trails Day 2020. The American Hiking Society is seeking to amplify Black voices in the outdoor community and advocate for equal access to the outdoors. Klaus Vedfelt / DigitalVision / Getty Images

This Saturday, June 6, marks National Trails Day, an annual celebration of the remarkable recreational, scenic and hiking trails that crisscross parks nationwide. The event, which started in 1993, honors the National Trail System and calls for volunteers to help with trail maintenance in parks across the country.

Read More Show Less
Indigenous people from the Parque das Tribos community mourn the death of Chief Messias of the Kokama tribe from Covid-19, in Manaus, Brazil, on May 14, 2020. MICHAEL DANTAS / AFP / Getty Images

By John Letzing

This past Wednesday, when some previously hard-hit countries were able to register daily COVID-19 infections in the single digits, the Navajo Nation – a 71,000 square-kilometer (27,000-square-mile) expanse of the western US – reported 54 new cases of what's referred to locally as "Dikos Ntsaaígíí-19."

Read More Show Less
World Environment Day was put into motion almost fifty years ago by the United Nations as a response to a multitude of environmental threats. RicardoImagen / Getty Images

It's a different kind of World Environment Day this year. In prior years, it might have been enough to plant a tree, spend some extra time in the garden, or teach kids the importance of recycling. This year we have heavier tasks at hand. It's been months since we've been able to spend sufficient time outside, and as we lustfully watch the beauty of a new spring through our kitchen's glass windows, we have to decide how we'll interact with the natural world on our release, and how we can prevent, or be equipped to handle, future threats against our wellbeing.

Read More Show Less

Trending

Experts are worried that COVID-19, a primarily respiratory and airway disease, could have permanent effects on lungs, inhibiting the ability for divers to continue diving. Tiffany Duong / Ocean Rebels

Scuba divers around the world are holding their metaphorical breath to see if a coronavirus infection affects the ability to dive.

Read More Show Less