The fishermen trying to save the world's biggest fish

Here you can see whale sharks and manta rays all year
Here you can see whale sharks and manta rays all year

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    Here you can see whale sharks and manta rays all year

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Here you can see whale sharks and manta rays all year 07:07

Story highlights

  • There's been a 79% decrease in whale sharks spotted in waters off southeast Mozambique
  • Climate change and unsustainable fishing methods are main factors in this decline
  • Locals fishermen, scientists and conservationists are working together to intervene.

(CNN)A small fishing boat bobbing in the Mozambique Channel might look like a vulnerable site -- especially when compared to what lies beneath it. But lurking below the whale shark -- the largest fish in the world -- is no threat to these fishermen; nor they to it. In fact, these locals might just be the key to saving this majestic creature.

The waters off southeast Mozambique are home to whale sharks, manta rays and a bounty of marine mega fauna. But this ecosystem remains delicately poised, and these creatures of the deep are extremely vulnerable.
    Manta ray sightings are down 88% in the last 10 years, and there's been a 79% decrease in whale sharks spotted.
    However a band of locals, scientists and conservationists are stepping in to stave off this decline.

    "I am alive because of the ocean"

    The small town of Inhambane, 290 miles northeast of the capital Maputo is one of the oldest settlements on the coast, dating back to the 11th century. Four hundred years later, Portuguese explorer Vasco De Gama set eyes on the town and named the area "terra de boa gente," or "land of the good people."
    Inhambane's epithet has echoed down the ages, and today nearby villagers at Tofo Beach are lending a hand in the conservation effort. Their way of life is bound to the Indian Ocean; it's in their interest to sustain it.
    "I am alive because of the ocean," says local fisherman Francisco Nhamussua. "I never went to school. My entire livelihood has always come from fishing."
    "I started fishing when I was 15 years old, with my father. I have spent my entire life fishing and I love it."
    From fisherman to ocean ambassador
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      From fisherman to ocean ambassador

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    From fisherman to ocean ambassador 08:40
    The area has become a diving hotspot drawing tourists from far and wide. This 215 mile stretch of coastline is unique to Mozambique, says marine biologist Anna Flam.
    "We have a year-round population of manta rays and whale sharks," she says, "you don't see that anywhere else."
    "We have the last viable population of dugongs on the entire east coast of Africa in the Bazaruto Archipelago... you can see different species of dolphins; seasonally we have humpback whales migrating through here -- and then of course all sorts of sharks, everything from great whites to bull sharks, to black tipped reef sharks and hammerheads."
    Flam and her colleagues at the Marine Mega Fauna Foundation (MMFF) have made some concerning discoveries during their analysis.
    The drops in whale shark and manta ray sightings have been put down to climate change and unsustainable fishing methods. One is a global problem. However the other can be rectified.
    Gill nets, hanging vertically in the ocean, are indiscriminate, and have caught everything from manta rays to turtles in the past. They were once the preferred fishing method for the people of Tofo Beach. The alternative, and one espoused by MMFF ambassador Nhamussua, is to return to fishing with a line.
    "As fishermen we have a responsibility to use correct fishing methods," says Nhamussua. "If we do that, then there will be plenty of big fish for everyone to share... [Gill nets] catch and kill baby fish, which could wipe them out."

    "An ocean without fish is not an ocean"

    If having enough to feed future generations wasn't incentive enough, there's the small matter of the $47 million marine tourism contributes to the national economy. (Of that, $10.7 million is from manta ray diving alone.)
    Swimming to save Mozambique's marine life
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      Swimming to save Mozambique's marine life

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    Swimming to save Mozambique's marine life 06:50
    "I view the ocean as a friend, a father, a provider," says Jerry, Nhamussua's son. He's training to become a dive master like Moises Francisco, who describes the ocean as his second home. As local leaders they sit at an important intersection: going underwater with tourists and observing wildlife, while reporting back the effects of pollution and malpractice to locals, most of whom cannot dive or swim, says Francisco.
    That's changing however, with MMFF initiative "Nemos Pequenos" ("Little Nemos") encouraging a new generation to swim -- and hopefully one day explore beneath the waves. In the four years since the program started, more than 1,000 young Mozambicans have been taught how to swim.
    With half of Mozambique's population under the age of 18, learning to respect the ocean and to interact with it safely could be the key to sustaining the nation's marine biology. And it's people like Nhamussua junior leading the way.
    "I really want to teach other people how to conserve the beach and the ocean," says the fisherman's son.
    "[An] ocean without fish is not an ocean."