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Marine Life & Conservation

Celebrating the biggest fish in the sea: International Whale Shark Day 2022

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On August 30, the world is showing the biggest shark that lives in our oceans some big, BIG love. Because believe it or not, the biggest fish in the sea needs all the love they can get! Sure they are a shark – but they are the closest thing to a vegetarian that exists in the shark world.  Filter feeders, they eat plankton. While their mouths are 4 feet wide, their throats are the size of a quarter. And before you begin to worry about their 3000+ teeth, you should probably know they are only the size of the head of a match.

It’s hard to believe given the fact they can grow up to 40 feet in length and weigh up to 20 tons, but they are very elusive and proficient in the art of underwater camouflage. In fact, Jacques Cousteau only saw three in his lifetime!

Photo: Simon J Pierce

They are found in all temperate and tropical oceans around the world except for the Mediterranean Sea, and can migrate thousands of miles between feeding areas. They spend most of their lives near the surface, but have been known to dive to depths of almost 2,000m.

These gentle giants are magical – with a unique dot pattern that is specific to each individual whale shark.  Their populations are so low that there is a genetic similarity among all whale sharks worldwide.  Whale sharks play an extremely important role keeping the oceans healthy while also creating sustainable income for local communities through tourism. However, like many other shark species, whale sharks are classified as Endangered on the IUCN Red List of Endangered Species, with declining populations worldwide.  With massive migratory areas that make them difficult to protect, the fact they are often bycatch or targeted for their meat + fins, and as filter feeders that they often consume micro-plastics, whale sharks need all the help they can get.

Photo: Rodrigo Friscione

Here’s everything you need to know about these incredible fish – including how to meet them, how to protect them, and how to celebrate them every day!

Whale Shark Fun Facts:

  • Name: Rhincodon typus
  • Size: 18- 40 feet
  • Weight: up to 20 tons (equivalent to 3 African Elephants, a full school bus or 12,000+ bricks!)
  • Physical features: mouths are 5 feet wide with 3,000 teeth, eyes are as big as golf balls
  • Life Span: estimated 60-100 years
  • IUCN Red List Status: Endangered

1) Love Tropical Waters Both Deep and Shallow

The preferred environments of whale sharks are tropical and temperate waters and all over the world, including both deep and shallow coastal waters and lagoons of coral atolls.

A marine biologist named Eric Hoffmayer recorded the deepest dive yet: in 2008, he monitored a shark in the Gulf of Mexico that descended 6,324 feet. Sharks lack a swim bladder that keeps other fish buoyant, so one idea is that whale sharks free-fall toward the seafloor to rest.

Whale sharks especially love the Philippines. In 2016, the 1000th whale shark was identified in Philippine waters, making the Philippines the third largest known aggregation of whale sharks in the world and the biggest in South East Asia.

2) Endurance Swimmers Who Are Global Travelers

Whale sharks are one of the most migratory species and can travel around 40 miles per day! They tend to prefer different geographic locations at various times of year based largely on water temperature, food supplies and breeding opportunities. Genetic studies show that whale sharks across the globe are closely related which suggests that mating is one of the reasons for such long travels.

It is believed that pregnant females will migrate long distances to be able to give birth near remote islands where baby sharks will be out of reach of common predators.

But they are also slow swimmers (for sharks) usually moving at no more than 3 mph. Their swimming pattern is different than most sharks in that instead of using just the caudal fin for primary propulsion, they use the full posterior two-thirds of their body length.

The record for whale shark migration was 12,000 miles by a whale shark named Anne in 2011. She was tracked making the mammoth migration from near Panama in the southeastern Pacific, to an area close to the Philippines in the Indo-Pacific. Other tracked whale sharks have traveled:

  • Over 8,000 miles from the Gulf of CA, Mexico to Tonga
  • 3,107 miles to the coast of Thailand

Photo: Julie Andersen

3) They Enjoy Alone Time

Whale sharks are usually solitary creatures but come together for months in large aggregations to feed in plankton-dense waters. After feeding, they drift off in random directions, completely disappearing during winter and spring.

4) They Practice Vegetarianism

Whale sharks can eat plankton up to 45 pounds of plankton each day (which is equivalent to  121 cheeseburgers per day). But they also eat shrimp, sardines, anchovies, mackerels, squid, tuna, and albacore. and fish eggs. According to The Nature Conservatory, whale sharks will wait as long as 14 hours for fish to spawn on reefs and then they will swoop in and eat the eggs.

But they also largely have a vegetarian diet, especially when other prey is scarce. Scientists discovered that whale sharks get more than half their nutrients from plants and algae.

5) Each Baby Whale Shark is a Miracle!

Whale sharks are ovoviviparous, meaning they produce eggs that hatch inside the mother’s uterus.  Litters can be up to 300 pups but not all pups are birthed at the same time. That is almost twice as many as any other shark species.

But only one pregnant whale shark has ever been studied and, interestingly, many of these embryos were at different stages of development. Scientists observed that some were still in their egg cases whilst others had emerged but were still in the uterus. This may signify that females are able to store a male’s sperm, selectively fertilizing their eggs over a prolonged period.

Juvenile whale sharks, as docile and vulnerable as their elders, often become prey for other sharks and orcas, so while a female may birth more than 300 pups at a time, survival rates are devastatingly low; females giving birth to multiple litters at different times could increase their survival rate which could be why they have their very own, built-in sperm banks.

Making the birth of a whale shark even more miraculous is the fact that each whale shark’s pattern is as unique as a human fingerprint!

Think You Know Whale Sharks? Click here for a fun way to test your whale shark IQ!

Header Photo: Whale shark in Oslob by Shawn Heinrichs

PADI  is the world’s largest ocean exploration and diver organisation, operating in 186 countries and territories, with a global network of more than 6,600 dive centres and resorts and over 128,000 professional members worldwide. PADI embodies a global commitment to ocean health and enables people around the world to seek adventure and save the ocean through underwater education, life-changing experiences and travel. Find out more at www.PADI.com

Marine Life & Conservation

New report shows simple measures needed to cut beach plastic pollution

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The Marine Conservation Society has launched its annual State of our Beaches 2023 report, highlighting the need for less single-use plastic items and more refillable options.

The charity’s beach cleaning programme, now in its 30th year, asks volunteers to record all litter that they find within a 100-metre stretch of beach. By gathering vital data from across the UK and Channel Islands, the charity creates change for cleaner seas and a healthier planet through policy and industry change. Last year, over 148 kilometres of beach were surveyed by volunteers, who removed 17,208kgs of litter from our coast.

Using data collected by over 14,000 volunteers, the State of our Beaches 2023 report shows that half of all litter collected came from public sources – either dumped, blown or washed onto our beaches.

Drinks-related litter, such as plastic bottles, caps and cans were one of the most found items, with an average of 16 found per 100 metres of beach surveyed. This figure is up 14% compared to the charity’s 2022 report.

Plastics caps and lids were recorded on 89% of surveys, with over 30,000 found in total. Plastic bottles were also commonly collected, with 73% of surveys finding this single-use item – a 4% increase compared to 2022. The charity’s inland litter pick survey, Source to Sea, also reported finding plastic bottles on 92% of cleans.

However, the charity’s State of Our Beaches 2023 report also indicates that some types of litter are on a downward trend. Although still in the top 10 litter items, disposable plastic cutlery, trays and straws were found on 5% fewer beaches across the UK, showing that bans on these plastic items between 2022 – 2023 could be working. The presence of plastic cotton bud sticks also dropped by 14%.

Lizzie Price, Beachwatch Manager at the Marine Conservation Society, said, “Half of the litter found on our beaches originates from public sources, underscoring the pressing issue of single-use plastic. Evidence shows that refillable alternatives and litter return schemes effectively reduce rubbish, as demonstrated by the decline our data has shown in items like plastic bags and disposable cutlery.

“Urgent and decisive action from UK governments is needed to accelerate our shift towards a circular economy, where we reuse, repair and recycle. The public needs greater access to refillable products and systems need to be implemented in which manufacturers are responsible for their waste.”

Governments across the UK have committed to delivering deposit return schemes from October 2025. However, the proposed scheme in England does not include glass items, despite glass being found on 52% of beaches in 2023. The charity is calling for governments across the UK to introduce compatible all inclusive deposit return schemes as soon as possible. This would see aluminium cans, and plastic and glass bottles have a 20p deposit which would be returned when recycled which would reduce drinks-related pollution.

Businesses are, however, starting to take refillable and reusable options into their own hands. Supermarket chain, Aldi, the largest corporate funder of the charity’s 2024 Beachwatch programme, is already leading the charge in refillable items by trialling refillable options for cereals and porridge oats in their stores over the past 5 months.

Plastics and Packaging Director, Luke Emery, from Aldi, who are running 4 beach cleans for staff and volunteers in 2024, said, We are continually working to reduce single-use plastics and packaging, and making unpackaged product options more commonplace for our customers is a key part of this. We are really pleased with the uptake of our refillable range so far by customers. Not only are we making sustainable shopping more accessible, but we also offer refill products for a better price than the packaged alternative, helping our customers save money.”

Marine litter is one of the biggest threats to our seas, with plastic breaking down over time into microplastics and threatening marine life which can ingest or become entangled in them. The Marine Conservation Society is urging the UK Government to move faster on its policies to cut down plastic waste and prevent items from reaching our seas.

To find out more about the charity’s beach cleans and how to get involved, please visit mcsuk.org/beach-cleans

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Guarding Against Coral Invaders

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Protecting (Dutch) Caribbean Reefs from Unomia stolonifera

Recent reports highlight the concerning spread of the invasive soft coral, Unomia stolonifera, currently devastating Venezuela’s marine ecosystems and detected in Cuba. With the potential threat of its expansion to the (Dutch) Caribbean islands, urgent action and awareness are essential to safeguard marine biodiversity and local economies from possible catastrophic consequences.

Invasive species are animals or plants from another region of the world that don’t belong in their new environment. These species can have major ecological effects by decimating native flora or fauna. They can also cause large economic losses and impact human health. Invasive species also pose a significant threat to marine ecosystems worldwide, including the Dutch Caribbean. Among these invaders is the octocoral species Unomia stolonifera or “Pulsing Xenia”, originally from the Indo-Pacific. With its rapid growth and lack of natural predators, this species can outcompete native species and disrupt fragile marine habitats such as seagrass beds and coral reefs.

Background

The invasive soft coral U. stolonifera was first identified in 2014, off the coast of Venezuela. It is believed to have been introduced via the illegal aquarium trade.  Since this species can reproduce sexually and asexually (or fragment), even small pieces can regenerate to spread.  Once introduced it quickly took over shallow reefs and hard substrate at depths of 0-50 meters, outcompeting local corals and seagrass for space.  Follow on surveys found that this coral species exhibited average percentage cover as high as 80%, vastly outcompeting native corals. In highly colonized areas, fish are disappearing due to loss of habitats.

In 2022, during a survey conducted in Cuba by the University of Havana, an unknown octocoral was discovered which was later identified as the invasive Unomia stolonifera. It is suspected that the coral larvae arrived in ballast water from fossil fuel ships originating from Venezuela, as nearby sites adjacent to Venezuelan ports have been heavily affected by the invasion.

How to help

Prevention through continuous monitoring, particularly in high-risk areas such as marine harbors and oil facilities, is paramount. Early detection plays a pivotal role in mitigating the threat posed by Unomia stolonifera.

The public’s involvement and awareness are also vital. Local communities, recreational divers, tourists, and all stakeholders are urged to participate in early detection efforts by reporting sightings (photo, location and date) of this invasive coral to their respective Protected Area Management Organization (PMO’s)- the Fundacion Parke Nacional Aruba (FPNA)STINAPA BonaireCARMABI Curaçao Saba Conservation Foundation (SCF)Nature Foundation St. Maarten (NFSXM) and St. Eustatius National Parks (STENAPA). If an invaded area is confirmed, follow the recommendations by the local PMO’s.

Keys to Success

Despite the challenges, early detection is key to mitigating the threat posed by Unomia stolonifera. With continued vigilance, research, and community engagement, there is hope for containing this potential issue before it becomes a major threat.

About the DCNA

The Dutch Caribbean Nature Alliance (DCNA) supports (science) communication and outreach in the Dutch Caribbean region by making nature related (scientific) information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and through the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.

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