A whaling day near the town of Torshavn on the Faroe Islands in 2011. Andarija Ilic/Reuters The people of the Faroe Islands, 18 mountainous islands off the coast of Northern Europe, have a longstanding tradition that has drawn ire from animal advocates: From as early as 1584, the Faroese have been killing pilot whales by the hundreds.

And this whaling becomes even more prevalent in the summertime.

In the past few weeks, photos and accounts of the annual whale drive have been surfacing on social media and in the news, with troubling images of blood-stained water and beached carcasses.

Conservation groups, like PETA UK and Sea Shepherd, are strong opponents of the whaling, which is illegal in Denmark. But the Faroe Islands have laws independent of Denmark's — laws that animal advocates from other countries are currently protesting against.

Whaling on the Faroe Islands is not for sport or spectacle. The meat and blubber are split amongst the population for consumption. The Faroese get a lot of international backlash, but they are keen on defending this longstanding tradition. Even the evidence suggests that while it may seem cruel, it's actually sustainable.

According to Whales and Whaling in the Faroe Islands, the yearly catch is around 800 animals. And the total population in the area around the islands is approximately 100,000 pilot whales.

Michael Moore, a senior research specialist in biology at the Woods Hole Oceanographic Institute, weighed in on the discussion.

"A mortality rate of 0.8% is very unlikely to be unsustainable given that marine mammal populations have the potential to grow at annual rates significantly higher than that number given adequate prey and lack of other overwhelming mortality factors," Moore told Business Insider. "However, this species is highly sociable and the impact on survivors of removal of social subunits is not understood at all."

The ecological effects aside, the real issue for islanders may be that — due to decades of ocean pollution from around the world — the whale meat coming eaten in the Faroe Islands is contaminated with mercury, which can be highly toxic to humans.

What the hunt is like

In the end, it's the way in which is hunt is conducted that's part of what seems so hard for people outside the Faroese community to understand, though the Faroese themselves say that it's regulated in a way to cause as little suffering as possible

—Blue Planet Society (@Seasaver) July 26, 2016

During the hunt, boats and jet skis corral the pilot whales into the shallows, where men are waiting to hook the blowhole and pull them onto shore. They then cut the spinal cord with a knife.

While the hunt is meant for pilot whales, other animals get taken down, too. EcoWatch reported that white-sided and bottlenose dolphins are often slaughtered in the events. Orcas are even trapped in the chaos and killed sometimes, as well.

The future of the hunt

Despite the recent protests, this traditional hunting method has been used on the 18 Faroe Islands for over 400 years. It doesn't appear to be going away anytime soon.

"This hunt will only stop when the Faroese deem it in their best interest to do so. I suspect that vocal opposition from other cultures will only reinforce their will to continue," said Moore. "There have been legitimate public health concerns raised for the human health of those that consume these animals."

The Whale and Dolphin Conservation Society reported that pilot whales in the Faroe Islands region carried high levels of mercury in their meat and blubber. Consumption of this contaminated whale meat has been linked to neurological delays and other development problems in children, as well as an increased risk ofcardiovascular problems and Parkinson's disease in adults. In 2008, whale meat was banned from Faroe Islands hospitals, but the conservation society says that otherwise progress on this issue has been "painfully slow."

People of the Faroe Islands slaughter pilot whales each year to use for food. Andrija Ilic/Reuters

Toxic whales

The protests of outsiders aside, however, it's possible that participating communities may slowly start to lose interest in whaling if whale meat is seen as harmful.

"For centuries the pilot whale has been an important part Faroese life – both in regard to food and culture," a team of Faroe Island government researchers wrote in 2012. Yet based on "the latest research results ... the conclusion from a human health perspective must be to recommend that pilot whale is no longer used for human consumption."

"It is with great sadness that this recommendation is provided," the researchers added.