It’s International Whale Shark Day! So how’s the world’s greatest fish doing in 2024?

By MMF co-founder, Dr Simon Pierce

It’s International Whale Shark Day! Which, in a shocking twist, seems like a great opportunity to chat about… whale sharks!

I’ve been privileged to work with these starry wonderfish since 2005, when I saw my first whale shark off Mozambique. I’ve been a mostly full-time whale shark researcher ever since.

 Many of you will know, because I tell people relentlessly, that I got into science as a tool to inform conservation efforts – particularly for under-appreciated animals. Decades later, that remains my mission in life.

 Back in 2005, I was doing my PhD on stingrays in Australia. My labmate Andrea was pestering me to come over to Africa to help her with manta ray research, and to take a look at the whale sharks she was driving past each day. I wasn’t particularly interested. Stingrays are cool, and nobody seemed to know much about them. Whale sharks were enormous, famous, documentary stars, and therefore BORING.

BORING

Andrea can be persistently annoying, so to humour her / shut her up I did start looking into whale sharks. And… wow. Okay. There was some pioneering research being done at places like Western Australia, Belize, and the Seychelles, but knowledge on the species was definitely scarce and, as near as I could tell, most of the documentaries at the time had flat-out made up their biological storylines. 

Meanwhile, threats were clearly high. There were active, targeted fisheries going on in SE Asia, and observational evidence of major declines in whale shark populations. These huge, placid sharks were in serious trouble… and therefore a lot more interesting to me :)

Twenty years later, I’m still learning, and they’re still amazing. We’ve come a long way since 2005, fortunately. We know a lot more about them, and we even have a ‘day’ for them!

International Whale Shark Day is a great excuse to talk about where whale sharks are ‘at’, conservation-wise. 

First though, some context:

Modern-day whale sharks have been around for at least 20-odd million years. Over that time, the oceans have literally changed shape. The species has survived warm oceans, ice ages, while avoiding giant predatory sharks and ‘killer sperm whales’. Contemporary whale sharks probably live to 80–100 years old, and don’t even become adults until they’re 30–40. They’re really, really good at avoiding drama and quietly getting on with things, while munching as much plankton as inhumanly possible.

What they can’t cope with is the rapid changes that humans have created. Since 1950, within the life of many whale sharks that are still swimming around today, the number of people on earth has tripled. Annual plastic production has gone up 200x, from 2 million tons per year to 400, much of it ending up in the ocean. The world’s shipping fleet has also tripled, with 20x more cargo transported. Open-ocean fisheries barely existed in 1950; now, there are hundreds of thousands of large fishing vessels in international waters.

It’s easy to see why whale sharks, and many other ocean animals, are struggling.

A container vessel passes through a whale shark feeding area off Mexico

We collated data for a global assessment of whale shark conservation status, the IUCN Red List, in 2016. In 2021, we updated and added to this global assessment through the IUCN Green Status process. In the past couple of years we’ve done further analysis on global shipping and some other ‘cryptic’ threats.

Since the 1980s, over half of the world’s whale shark population has been killed by people. They are a globally endangered species, and may be critically endangered in some regions. Targeted fisheries, and likely shipping mortality, did most of the damage.

Fortunately, there has been a concerted effort to reduce the demand for shark fins and meat in China and Taiwan, and that has had a significant benefit for whale sharks. China, India, the Philippines, and Taiwan, which previously had large whale shark fisheries, have now banned intentional catches of the species (I'm not saying it doesn’t happen, but it doesn’t happen nearly as much).

At this stage, my main concerns for their survival are ship strikes and gillnet fisheries. Deaths from shipping are very difficult (practically impossible) to track, as ships move fast and whale sharks generally sink when killed. To an extent, we can track regional risk by the number of sharks that have survived impacts – the Gulf of Mexico and Arabian / Persian Gulf are areas of particular concern. 

The best way to protect these sharks is to seasonally re-route ships, or at least have them slow down when they’re near the (small, predictable) areas where whale sharks routinely feed on the surface in large numbers, as can be seen off Mexico, Qatar, and the US.

A propeller-cut whale shark

Gillnet fisheries are another tricky one, as there’s little monitoring of this fleet, and it's huge – tens of thousands of vessels in the Indian Ocean alone, fishing with nets up to around 17 km in length (over 10 miles). These nets are, of course, designed to be hard for fish to see and avoid.

Plastic ingestion is also a threat to whale sharks and other filter-feeders – one that we’re only starting to understand.

Unmanaged tourism is a very visible issue in some areas, and I’m not discounting it – it can put extra pressure on whale sharks at key feeding sites. I’m a firm believer in the conservation potential of ecotourism… but too much whale shark tourism falls well short of that standard. 

(Swimming and diving with whale sharks can be amazing! Look for operators that support research and conservation efforts, and promote best-practice standards for whale shark swimming.)

Mass tourism in the Maldives

Can we fix it? Yes we can!

Whale sharks are legally protected in *most* of the countries that are known to host important constellations (Madagascar and Oman, we’d love you to join the list!), and long-term protection efforts are starting to pay off. For instance, Western Australia – the spiritual home of whale shark research and ecotourism – has been seeing a fairly steady increase in whale shark sightings over the past decade. There are a lot more people interested in whale shark research and conservation, and we’ve got an amazing AI-assisted global whale shark ID database at sharkbook.ai, with over 14,000 individual whale sharks identified from around the world. These monitoring efforts are helping us prioritise threats and implement countermeasures on a global, regional, and national level.

Personally, it's always helpful to remind myself what can be achieved. I’ve just wrapped up fieldwork in Australia, where we watched thousands of humpback whales happily splashing about as they migrated past. After almost being wiped out by the 1960s, they’re nearly back to pre-whaling numbers. Turns out, we just needed to stop killing them.

For whale sharks, too, the answer is ultimately that simple. It takes a hell of a lot of efffort to achieve, but – with all of us working together – these gentle giants can bounce back. So lets make the next year a fantastic one for the world’s greatest fish :)

Thanks for reading! You can find out more about MMF’s whale shark work here: https://marinemegafauna.org/whale-sharks

We literally couldn’t do this work without our partners and donors, so a whale shark-sized thanks to all of you :)

Simon.