By James Griffiths, CNN

(CNN) -- A near constant wind buffets the top deck of Boat 36826 as it patrols the seas north of Hong Kong's largest island, Lantau.

Sitting in a white plastic lawn chair, staring intently through a pair of large, black binoculars, Charlotte Lau pulls a multicolored scarf high over her face and zips up her grey hoodie.

Down a steep staircase in the boat's main cabin, her boss Taison Chang sorts through the supplies piled on seats and a wide, curved table -- maps and charts, a GPS tracker, snacks, waterproofs, two-expensive cameras with long lenses, and several bottles of suncream in defiance of the dreary skies overhead.

Next to Lau, holding a walkie-talkie and shivering in a blue t-shirt, Viena Mak writes on a clipboard as her co-worker says: "no sighting."

It's a phrase the trio are becoming depressingly used to. They work for the Hong Kong Dolphin Conservation Society (HKDCS), which sends researchers out almost every day, no matter the weather, to search the city's waters for an ever-shrinking population of dolphins.

Their relentless work matters, not just to keep a few individual animals alive, but as a test of whether Hong Kongers can have more of a say in how their city progresses, take a step back from the mega projects and uninhibited development that have characterized Hong Kong for decades, and act to preserve what made it special in the first place.

I. Ancient 'ruddy' residents

On a day in July 1637, British explorer and trader Peter Mundy sat at anchor aboard the ship "Planter," near what was then still the Portuguese colony of Macau.

Mundy -- who would go on to help introduce tea to the UK, forever changing British drinking habits and imperial priorities -- wrote in his diary, "the Porpoises here are as white as Milke, some of them Ruddy withall."

It was one of the first recorded mentions of the Chinese white dolphin, but would go largely unnoticed until another European, Swedish missionary and naturalist Pehr Osbeck wrote of "snow-white dolphins (which) tumbled about the ship" and suggested a scientific name for them: "delphinus chinensis."

Now officially the Sousa chinensis (to reflect their relation to the wider Sousa, or humpback dolphin, genus), the animals are more commonly known as pink dolphins due to their pink bubblegum-like coloring in adulthood.

Growing up to 2.5 meters (8.2 feet) in length, with short, stubby snouts and small dorsal fins high up on their arched backs, pink dolphins have lived in the waters around Hong Kong for hundreds of years, as the human population grew from the low thousands in the 1600s to the millions today.

Throughout that time, pink dolphins -- and to a lesser degree the finless porpoise, another local cetacean -- were a common sight for Hong Kong fishermen, who regarded the animals as a catch-stealing nuisance at best, and an evil omen at worst.

Seeing pink dolphins leap out of the water was said to be a harbinger of storms; one old story has it that in 1941, fishermen off Yau Ma Tei saw a particularly large pod cresting three days before the Japanese Air Force began bombing the city.

While some saw dolphins as having an effect on human affairs, no one took much mind of what people might be doing to the dolphins until the 1990s, when scientists began sounding the alarm that population numbers were plummeting.

Today, there are an estimated 10,000 pink dolphins globally, with the largest population, around 1,200, in the Pearl River Delta region. HKDCS estimates 47 dolphins currently make the city's waters their home.

II. Breathing room

Hong Kong is dense. The city squeezes 7.4 million people into an area three times smaller than Rhode Island, with 57,250 people per square kilometer in the busiest neighborhoods.

For hundreds of years, the solution to this density has to be to carve out a bit more space by filling in parts of the sea. Industrial land reclamation began in earnest in the late nineteenth century, as the city's British rulers attempted to expand their new possession by dredging out bays and advancing shorelines.

At its most basic level, land reclamation is the process of scooping rock and other materials from a hillside and dumping them into the sea until the resulting pile is high enough to be built upon. However, this method results in "large displacement of the marine sediments and the development of mud-waves beneath the reclamation fill," according to a 1996 government review.

Such underwater disruption can destroy habitats and release toxic materials trapped under the mud into the surrounding water -- potentially decimating fish and other local marine populations.

In order to address these concerns, attempts have been made to minimize the environmental impact by using vertical wick drains like giant straws to suck moisture out of the mud, making it solid enough to be built upon, but even the most minimal reclamation work is a major engineering undertaking creating extra marine traffic and huge amounts of noise and disorder underwater.

Despite these precautions, Samantha Lee, manager of oceans conservation at the World Wildlife Fund's Hong Kong office, warned that because dolphin numbers are already diminished -- and they face a multitude of other challenges -- they are particularly vulnerable to continued construction work.

"The government has been adopting a 'develop first, conserve later' approach," she said.

III: Reclaimed waters

A constant stream of planes passes overhead, deafening the crew of Boat 36826 as they near a line of white buoys strung out over the water north of Hong Kong International Airport. Inside the perimeter sits a cluster of barges with red-and-white towers reminiscent of oil derricks, carrying out the drilling, dredging and pumping that will add the extra 600 hectares (1,480 acres) of land to Chep Lap Kok island needed to house a third runway.

The runway is one of two megaprojects in the waters around Lantau that HKDCS and others warn could be the final nail in the coffin for the local dolphin population. Near the airport, the sound of a drill rings loud over a huge building site, a 1.5 square kilometer (0.5 sq mile) pile of stone and sand that will one day house a transportation hub at the end of a $14.9 billion, 30 kilometer (18.5 mile) long bridge and tunnel stretching from Chep Lap Kok to Macau and the Chinese city of Zhuhai, on the other side of the Pearl River Delta.

The bridge -- which the government argues is necessary as marine traffic between Hong Kong and its neighbors increases -- has been plagued by criticism since its beginning, over its environmental impact, worker safety, and sprawling budget, among other issues. But most Hong Kongers do not have a say in how major development projects are approved.

Less than 1% of the city's population selects its leader, who — along with an appointed executive council — can sign off on many projects with limited scrutiny from the partially democratically-elected legislature.

Aboard Boat 36826, opinions towards the bridge are predictably negative. Mak, who was born in Macau, laughs dismissively at the government's justification. Lau says the bridge "does not benefit Hong Kong people, it just benefits businessmen who want to transport their goods more cheaply than by ferry."

"They don't care about nature," she adds. "They just want to make money."

"Most of the destruction (of nature) is non-reversible," HKDCS chairman Chang says later. "It's like we keep withdrawing money from a bank account but we never deposit anything, so now we've almost run out of money but we still want to use credit cards to continue to spend."

For Chang and others, the pink dolphin is a test of whether Hong Kong can cultivate a new approach that values nature as much as property and works to preserve the past as well as develop the future.

The bright red high-speed ferry slows to 10 knots as it crosses the boundary of the Brothers Islands Marine Park just ahead of Boat 36826.

The park, along with two others due to open in 2018 and 2019, is a protected area designated for dolphin conservation. The scheme is intended to offset disruption caused by development projects like bridge and third runway, but many dolphin advocates argue they are too little too late (the Brothers park was not opened until five years after bridge construction began) and do not reflect how the animals actually behave.

"Dolphins have a large range, you can't build marine parks for them in such fragmented places, they need a wide protected area for long term survival," Chang says as the boat passes between the two islands that give the park its name.

Pointing to the still visible building site next to Chep Lap Kok he adds: "You can imagine all the noise underwater, all the construction vessels next to the marine park. This will have a great impact on the function of the park."

In a statement, Hong Kong's Agriculture, Fishers and Conservation Department (AFCD) said any affect the twin construction projects have will be temporary.

"Once construction work is complete, the associated disturbance will cease and it is expected that habitat displacement due to construction activities will recover," the department said.

A new 2,400 hectare (5,930 acre) marine park is due to be designated following the completion of the two megaprojects. AFCD said it considered doing so earlier, while construction was ongoing, but this was deemed "not practicable."

IV: Autopsy

The corpse lay half on its back, its distended stomach facing the sky, pink underside turned a deep, ugly maroon. Flaps of yellowed skin hung off it, like peeling sunburn.

Dressed in a white boiler suit, blue surgical gloves and a dust mask, the vet leaned over and delicately sliced the animal's stomach open with a scalpel.

A smaller dolphin fell out in a spill of bloated, red intestines. The calf was gray in color, with beady eyes and a partially formed snout, and just as dead as its mother.

More than 110 dolphins have washed up on Hong Kong's beaches in the last four years, nearly all of them dead and in a state of decomposition.

Most are killed by boat strikes, or wounded by nets and ropes, says vet Paola Martelli as he flicks through dolphin x-rays in his surgery in Ocean Park -- a sprawling aquarium, zoo and theme park on the south side of Hong Kong Island.

Whenever a beached dolphin is spotted the park sends out a team to carry out an autopsy and determine the cause of death or, very occasionally, bring the still living dolphin to the park for treatment, with limited success.

"They always die. They always die," Martelli says, explaining that by the time most dolphins come into human hands, they have suffered life threatening injuries, and even those which survive initially often succumb to secondary infections.

"It's good for the heart and it's meaningful because a lot of the trouble they're in is because of us, so there's a moral obligation to try, but in terms of outcomes, it's not a species that has a good outcome," Martelli says.

In a large building adjacent to his surgery, Ocean Park's pod of bottlenose dolphins -- a distant cousin of the pink dolphin -- swim through a series of light-blue colored pools, emitting clicks and the occasional high-pitched squeak.

One dolphin flops onto a raised platform and opens her mouth -- displaying dozens of small, white teeth and a large, muscular tongue -- to allow Martelli to carry out a routine dental exam, splashing her head in disapproval when she sees an anesthetic needle but otherwise complying happily. "She hates injections, but loves the attention," the vet says.

These dolphins, foreign imports to the city, are nevertheless the ones most familiar to many Hong Kongers, tens of thousands of whom troop through the park every year.

The Ocean Park Conservation Foundation spent upwards of $1.1 million on conservation and public awareness projects in its most recent financial year, including three major studies of the Chinese white dolphin population. Despite the park's efforts however, its executive director, Suzanne Gendron, said many visitors were still surprised to learn the pink dolphins exist.

"It's such a common response: 'oh we have Chinese white dolphins, we have pink dolphins in our waters? I've only seen the ones at Ocean Park'," she said.

V: Up a creek

Boat 36826 rocks violently as the Benita Schulte, a colossal, 50,000 ton Liberian-flagged cargo ship powers past, carrying red, green and blue stacked containers en route to the Port of Hong Kong, one of the busiest in the world.

Last year, more than 370,000 vessels passed through the port, including huge container ships, small fishing boats, high-speed ferries, tugs, and cargo vessels of all shapes and sizes, churning up the water around them as they joined the constant stream of marine traffic into and out from the Pearl River Delta (PRD).

The delta region stretches from the Chinese metropolises of Guangzhou, Dongguan and Foshan in the north, to Hong Kong and Macau in the south, where three rivers and a host of small tributaries meet and combine as they pour into the sea.

The PRD is home to the world's largest population of Chinese white dolphins, estimated to less than 2,500 individuals, a minority of whom live and hunt in Hong Kong waters. Exactly how many is, like many things to do with dolphins, subject to some controversy.

According to AFCD figures, the Hong Kong dolphin population currently sits at 47, down from around 90 in 2010. While some research suggests those 47 are part of a larger transient group of a couple hundred, not all of whom live in Hong Kong waters year round, all agree the numbers are dropping.

In a statement, AFCD said the drop in numbers for Hong Kong dolphins may be due in part to them shifting their habitat to Chinese waters, something the department predicted would be reversed once conditions in the city improve again.

Dolphins are moving, but that doesn't mean they're headed into safer or more hospitable locations, said WWF's Lee. South of Hong Kong is one of the world's busiest shipping corridors, while in the north and west, Chinese cities have many of the same problems as Hong Kong -- land reclamation, marine traffic, and pollution.

In the decade leading up to 2012, the PRD grew to be the "fourth largest trading economy globally," according to InvestHK, with a GDP equivalent to that of South Korea. Plans are underway to turn the entire region into a megacity of more than 67 million people, while major reclamation projects have been approved or are in progress in Macau, Shenzhen, Zhuhai and other parts of Guangdong province.

"If the dolphins are forced the leave the Hong Kong area to the rest of the Pearl River Delta, then the threat to them is greater," Lee said. "The entire population could die out."

This makes the fight to save dolphins in Hong Kong all the more important. Not only are conservationists seeking to save the city's native population, they want to prove that such a feat is possible, that a downward trend can be corrected.

They are pushing back at something which has plagued conservationists for centuries -- shifting baseline syndrome -- where each generation's perceptions of what is possible are shaped by what they grew up with.

"Overfishing may eat away at fish stocks, or even drive species extinct," explains Jon Mooallem in "Wild Ones," his book on the topic. "But when the next generation of scientists start their careers, they don't see the oceans as depleted; that depleted condition becomes their baseline, against which they'll measure any subsequent losses in their lifetimes."

Much of the time, baselines are shifting in the direction of a denuded, lesser nature -- more extinctions, more endangered species. But very occasionally, the opposite occurs.

In 1941, there were a total of 16 living whooping cranes, and the species was almost wiped out. As of 2015, there were 442 living in the wild, and another 161 in captivity. The gray whale was nearly hunted to extinction before it was granted international protection in 1947, in the time since, population numbers have swelled to the tens of thousands. And last year, for the first time in a century, the number of wild tigers increased, by more than 600.

It's successes like these that keep the pink dolphin conservationists going -- educating people about reducing pollution and marine waste, encouraging them to lobby the government, and pushing for a development policy that puts nature on par with profit.

There's a point when, staring at the sea for hours on end, everything looks like it could be a dolphin. Every white cap is a head sticking out of the water, every piece of flotsam is a dorsal fin.

After eight hours of searching, Boat 36826 slows as it passes under a section of the bridge, a giant outcrop of grey concrete covered in spindly metal scaffolding. As the boat enters Tung Chung Bay, in the shadow of the airport, the crew begins stowing their equipment.

The clipboard Mak was holding at the beginning of the day is now covered in writing, a record of the boat's journey from near Kowloon, north to the border with China, to its end point on Lantau island. In the rightmost column, titled "sighting," is one entry repeated 22 times: "no."

Chang shrugs as he, Mak and Lau stand on the pier, their hair windswept and salty, their faces and clothes specked with seawater. He should be used to this by now, he admits, "but I still feel disappointed every time."

They go out again the next day.