Greta Thunberg was detained by police at a demonstration in The Hague, in the Netherlands.

The climate activist was put in a bus by local police along with other protesters who tried to block a major highway into the city on Saturday.

Thunberg had joined a protest by hundreds of activists and was detained when she joined a group of about 100 people who tried to block the A12 highway.

Before she was detained, Thunberg said: “We are in a planetary emergency and we are not going to stand by and let people lose their lives and livelihood and be forced to become climate refugees when we can do something.”

The road has been blocked for several hours dozens of times in recent months by activists demanding an end to all subsidies for the use of fossil fuels.

At previous protests, police drove detained protesters to another part of the city, where they were released without further consequences.

Thunberg was seen flashing a victory sign as she sat in the bus used by police to take detained demonstrators from the scene.

The Extinction Rebellion campaign group said before the demonstration that the activists would block a main highway into The Hague, but a heavy police presence, including officers on horseback, initially prevented the activists from getting on to the road.

A small group of people managed to sit down on another road and were detained after ignoring police orders to leave.

Extinction Rebellion activists have blocked the highway that runs past the temporary home of the Dutch parliament more than 30 times to protest against subsidies.

The demonstrators waved flags and chanted: “We are unstoppable, another world is possible.”

One held a banner reading: “This is a dead end street.”

In February, Thunberg, 21, was acquitted by a court in London of refusing to follow a police order to leave a protest blocking the entrance to an oil and gas industry conference last year.

Her activism has inspired a global youth movement demanding stronger efforts to fight the climate crisis since she began staging weekly protests outside the Swedish parliament in 2018.

She has repeatedly been fined in Sweden and the UK for civil disobedience in connection with protests.

In the early 1960s, Canada’s fisheries ministry installed a .50-calibre machine gun on an island in British Columbia. The weapon, typically used against armoured vehicles and low-flying aircraft, was mounted with the sole purpose of killing orcas. The high-powered gun was never used, but the message was clear: the whales, derisively called “blackfish”, were the enemy.

Now, six decades later and less than 100 miles away from where the gun was mounted, that same ministry has joined residents of a remote community in a frantic attempt to rescue a stranded orca calf.

For the last two weeks, the two-year-old calf has been trapped in a lagoon off the wind-battered west coast of Vancouver Island. Immense resources from Indigenous communities and Canada’s federal fisheries department have been marshalled to rescue the calf, which has been named kʷiisaḥiʔis (pronounced kwee-sahay-is), by local First Nations – a name that roughly translates to Brave Little Hunter. Amid the intensifying effort to free her, the outpouring of community support highlights a dramatic shift in public perceptions of the whales, from nuisances to be culled into beloved individuals worthy of a challenging and costly rescue.

The saga began on 23 March when residents of a coastal community along the north-western reaches of Vancouver Island spotted an orca trapped on shore. It is unclear why the orcas entered the lagoon, but the remains of a harbour seal nearby suggest to experts the stranding may have been the result of a hunt gone wrong. Locals worked, unsuccessfully, for hours to rescue the 14-year-old mother, named Spong, who was trapped in a trough-like depression on the shore. Kʷiisaḥiʔis watched helplessly as her mother struggled, and cries of distress were heard from hydrophones placed in the water. Glen McCall, one of the first on scene, called the immense emotional and physical toll of the failed rescue an “absolutely horrible” experience.

In the weeks since, every attempt to lure her out, including the use of vocalisations from family members, banging metal pipes and laying ropes with floats attached, have all failed. But the calf desperately needs nutrition. While she seems healthy, experts caution that her health could decline quickly in the coming days.

In the days since Spong’s death and the collective rescue effort, kʷiisaḥiʔis has carried the weight of a community’s hope. Every few minutes, her narrow black dorsal fin breaks the surface of the lagoon near the village of Zeballos. What follows is a misty exhalation from the orca – and a collective sigh of relief from the dozens of experts glued to her every movement, and from the global audience heavily invested in the whale’s plight.

“I was out there the day the mother got stranded, and it really left a mark on me,” said Chris Copeland, who uses the Facebook page of a local inn to chronicle the health of the calf. The updates, he’s learned, are read all over the globe. “With the way the world is these days, I think people just really want something to hope for. We’re all cheering for the little whale.”

On the bridge that separates the lagoon from the Little Espinosa Inlet, cedar boughs hung by the Ehattesaht First Nation highlight the high cultural stakes of the rescue: the origin stories of the Nuu-chah-nulth people tell of a killer whale coming on to land and transforming into a wolf, which itself transforms into a human.

Last week, the Ehattesaht First Nation, alongside the neighbouring Nuchatlaht First Nation, launched a canoe into the lagoon in an attempt to draw the calf closer with their drumming, a “powerful” moment on the water. “Every discussion and the resulting decisions are guided by one single principle: what is the safest for [the calf] and has the most probability for success,” the Ehattesaht chief and council said on Thursday.

Paul Cottrell, one of the country’s most experienced whale rescuers, told reporters he had never worked on a mission so “difficult and complex” as the attempt to free kʷiisaḥiʔis.

“Time is of the essence for this calf, we know that, and the planning is well along, but we do have a little bit more planning, equipment and logistics to work out,” he said.

On Thursday, Cottrell and Ehattesaht chief Simon John announced a plan to trap kʷiisaḥiʔis next week if the whale doesn’t escape the lagoon on her own. Using seine nets, the team would probably guide the calf into a sling, transporting her on a truck and then releasing her into an open-water pen – a series of carefully orchestrated movements that cannot take longer than a few hours.

But rescuing the calf from the lagoon is only the first step. Once safe, she needs to be reunited with family in order to survive in the open ocean. The rescue team plans to hold her in a pen used for salmon farming until relatives are close enough for a release.

While dozens of experts, including vets and drone operators, closely monitor the calf’s health, the team is also drawing on communities and whale-watching boats on Vancouver Island’s west coast in an attempt to locate the family. Whale research group Bay Cetology has opened to the public its online AI-assisted photo database of all the region’s whales in an attempt to track the calf’s relatives.

The ability to identify whales by distinct markings, a technique developed more than half a century ago, marks a pivotal moment for how the public began to understand orcas as distinct, highly intelligent and social mammals, says John Ford, a leading expert and scientist emeritus with the federal fisheries department.

“Over the years, they were feared by fishermen in the region just because they’re a large, dangerous-looking animal with big teeth,” he said. Hastily devised plans like the machine gun reflected both the frustration and fear the whales elicited. “But once you could start identifying every whale along the coast, they became individuals.”

Despite the overwhelming odds against the rescue attempt, Ford sees glimmers of hope. Brave Little Hunter is a Bigg’s killer whale, an ecotype of the species that has different social structures than the endangered southern resident whales. With movement of Bigg’s whales to different pods, the calf might be able to link up with members of its extended family if it can leave the inlet.

The tireless efforts to save the calf don’t come as a surprise to Ford, who has assisted on previous local rescue attempts. “For an individual to be orphaned and on its own, people feel empathy and want to help. It’s just human nature,” he said. “This is not just a generic whale stuck inland. We know who it is and where it should be. And many people would like to see it back with its family.”