The Mysterious Megamouth Shark

Latest update January 24, 2019 Started on April 10, 2018

The Megamouth is one of our ocean's most enigmatic shark species. We know almost nothing about this iconic and mysterious deep-sea giant. Recently, Taiwan has had a spike in Megamouth encounters. When fishers catch a Megamouth, the crew cannot afford to release the shark, and they are sold in the fish markets. The captains on this very small fishing fleet have agreed to allow us to study, tag, and RELEASE these peaceful giants, if we compensate them for the price the animal would bring at the market.

April 10, 2018
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In The Field

Time to preserve specimens from the fish market. While it is exciting to bring new specimens home, the fixing process is a pain. We have to inject the specimens in formalin and let them fix for two weeks. It is definitely the less flashy side of shark research :/


Even though Megamouth Sharks can be quite large (reaching lengths of 20 feet), they only eat tiny prey. They are one of three filter feeding shark species, and an inspection of our specimen's stomach contents show that it ate krill, which what we expected based on the literature. It is hard to imagine such a large animal subsisting off small prey in the low prey density environment that lays beyond the photic zone. Hopefully with more research we can further study how this shark manages to meet its caloric requirements.


We have parasites! Megamouths appear to be a heavily parasitized species. We recovered a ton of parasites, which I believe represent several species from Megamouth specimens' gills, fins, and stomach. We need to study these specimens more, but we believe some of the parasites are new species.

Megamouth parasites are very poorly known. When scientists first investigated parasites found on Megamouth specimens they needed to create a whole new family to classify the parasites. We have high hopes that these specimens will contribute to our limited knowledge of Megamouth Sharks and the deep-sea fauna of the Northern Pacific.

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We received a phone call that a Megamouth shark was spotted at a fish market. Although it is deceased and will not be helpful in our tagging study we can get a wealth a data from a fresh shark and it would serve as a valuable specimen in a museum.

Getting a Megamouth specimen is rare, and it is a goldmine for science. However, finding transport for a huge shark, freezers accommodations, and paperwork to ship internationally has been a head ache!

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A few classy B&Ws shooting off Taiwan

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A few little throw back pictures of getting our baby set up for Megamouths. After our posting hiatus we are preparing to update the project page to stay tuned!

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During our market surveys we have seen a lot of different shark species. While it is always sad to see sharks caught and consumed, at least bycatch species are not going to waste. We collect as much information as we can along with some specimens. There is a lot of data valuable for science and hopefully management.

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Is that pizza batfish!?!?! Weird choice as a food fish. I've seen several of the shallow water longnose and redlip batfish, and figured that the stiff movements meant they were too bony to be popular as food fish.

This might be a gross post, but look at my hands!!! When working with sharks I always bring gloves then get too excited to put them on. Their rough denticles don’t hurt me while I work, but the next day I get shark burn on my arms and legs and my usually shed both hands. This is sometimes an issue with modern touch ID access (I’ve had to scan my pinkies for access to museum collections). Interesting/gross enough, my peeled off thumb print opened my phone!

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and dislike scientists because it is our job to stop them. As a result I was a little uneasy the first time I went to sea as a scientist on a commercial fishing vessel. However, since then I have only had good experiences working with fishers. Most of the time everyone is helpful and interested in the science.

This is very much the case in Taiwan. The fishers are excited for the project and unreasonably nice. They have been very accommodating, showing us around the boat, explaining the fishing process, currents, and tides. They even prepare meals for us. Not only does the friendly relationship make the work easier, but they have been willing to share a wealth of their fisher knowledge with us.

I am a firm believer that to future of our ocean depend not only upon responsible management, but cooperation between fishers, scientists, and policy makers. Working with the locals out here has been a lot of fun, and assures us that they would be open to reasonable policies protecting or limiting Megamouth catches if it was cased on solid data. Data that we hope to get during this trip.

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Part of what makes this project exciting for me is our high tech tags. We have 8 sophisticated pop-up satellite archival tags that will record everything our sharks do for the next 18 months. We will have location data, depth, water temperature, salinity, swimming speed, light levels, etc. We will attach the tags at the dorsal fin (on the sharks back) and they will collect data continuous until their release date. Then they will pop off, float to the surface, and transmit all their data to a satellite which will relay it to my laptop at my desk in California.

These tags are unique in the fact that they are capable of going to depths greater than 6,000 m (19,685 ft)! I don’t think Megamouths would swim that deep, but now we are ready to find out.

The tags are advanced and allow for you to customize the data they record and transmit. While this is a great option to have, it requires a little bit of programming. I am trained as a taxonomist and have had to take a crash course from the tag makers in how to set them up. It is a little bit of a challenge but I am happy to add it to my skill set.

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One of the things I love about Taiwan is the character of the boats. There is so much tradition in the fisheries and it is reflected in the harbors and on the ships. Harbors are colorful with local temples and no two boats are alike.

Taiwan’s long history of fishing and rich fisher knowledge mean that the locals know this water better than anyone, and I am relaying on that to help us find our ultra rare shark species. With a little work and communication we can tap into what these fishers have long known and tag a Megamouth.

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After finding a sea captain to take us out at night we crammed to get the gear ready. We had one day to prep the dive gear, safety equipment, arm the tags, and give our shinny new ROV a practice run.

We had set up it buoyancy for saltwater at the OpenROV head quarters, but we wanted to give it a test run in Taiwan. We’re glad we tested everything. The extra lights were bulky and the top mounted GoPro caused the little drone to flip.

After a little trail and error, we got our little sidekick all rigged and set up! She runs swiftly and easily, takes fast turns, and looks pretty bad ass to boot. We keep our fingers crossed that with a little luck we will be in water with a big shark in no time.

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Love the action shot!


After talking to locals we have been directed to a fish auction on on the Northeastern coast of Taiwan. This auction receives catches from around Taiwan and we were eager to checked out some of the weird sharks that they get.

Sharks are these markets are often taken as bycatch (caught by accident while fishings for other species) but are still consumed. We were interested to learn that there is a value on rare sharks and consumers like to eat unusual animals.

Among the species we saw were Blue Sharks, Bronze Whalers, and hammerheads. They also had a few Gulper Sharks which are rare, deep-sea sharks known for their slow reproduction. Finally we spotted one large (8.6 ft) False Catshark, a very rare species that is poorly known. This relatively large species has tiny teeth the size of grains of sand, and the pups (baby sharks) eat each other in the womb.

We talked to the auctioneer, and he said Megamouths, while rare in the market were seen a few times every year during this season. We were optimistic and excited to know that we were in the right place at the right time.


Paul and I are on the ground and well underway in Taiwan. The captain of our fishing vessel promises that we will indeed find a Megamouth.

Fisherman here primarily target sunfish. These gentle giants can weigh over a ton and typically make their way around slowly and awkwardly in search of jellyfish. Their size, and the fact that they can lay up to 300 million eggs at a time, make them a very sustainable food option here and in Japan. In the recent past, these boats have also been landing megamouths as well - and there is indeed a market for them.

In the coming weeks, we hope to not only tag these sharks, but we also want to explore the culture and commerce surrounding them. Science, conservation, and fishing are uneasy bedfellows. We are lucky enough to have connected with a captain who is interested in our work. We hope to find out a little more about the demand for Megamouths in the fish markets along the coast.

Tagging these giants will hopefully provide a wellspring of data to get a preliminary picture of their numbers and movement.

Science knows almost nothing about these animals. The only way we can begin to formulate a conservation plan is with the data from Paul's tags....

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Spending some time designing a tagging method. We are using 18 month tags we have to make sure the dart stays in place and nothing wears out or corrodes before the tag pop-off date.

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Very cool Paul! Will this be the first time a megamouth is tagged for this long?

Landed! After months of research, planning, and a grueling flight we landed in Taipei, Taiwan. We hop on a train and head south along the coast. This is not easy task with the mounds of gear that we have taken with us.

I am so happy to be back in Taiwan and excited to try to find a Megamouth shark.

When we get to our AirBnB we find out it is actually a failed spy. There are tiles on all the surfaces, a reception area with brochures, and the bedrooms are old bathrooms with beds crammed in them. As quirky as it is this place is it is perfect for the project: cheap, close to the harbor, and completely waterproof. We can lay our wet drive gear all over the place without worrying about the floors, and the metal rollup security doors will keep all our gear safe.

After doing a quick gear and safety check we are all eager to get the search underway.

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We made a quick stop in Berkeley, CA yesterday before jetting off to Taiwan to pick up the latest and greatest offering by OpenROV - the hot off the presses Trident underwater drone.

Zach and the team at OpenROV are passionate about making exploration something that is available to everyone. We hope to use the Trident to track tagged Megamouth sharks as they descend back into the depths.

We outfitted this guy with some add ons: three standard GoPro clips for side dive lights and an added GoPro 6 up top to give us a slightly different camera angle to use in conjunction with the onboard camera.

Using it is super easy! We were flying it around the test tank in minutes. Once we get to Taiwan, we'll be doing some buoyancy tests then putting it to use as we track the elusive Megamouth shark.

Thank you to everyone at OpenROV for hosting us! We'll report back from the field once we've road(?) tested the Trident!

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Great to meet you guys. Can't wait to see what you find with the Trident!

Thanks, David! We can't wait to post what we see with our souped up Trident!

Expedition Background

Although the Megamouth is a large species of shark reaching ~20 ft in length, it remained undetected by humans until about 40 years ago. Since its recent discovery very few Megamouths have been encountered with just over 100 individuals recorded in human history. However, a small fishing village in Taiwan is experiencing a large number of Megamouths a few weeks out of the year. These landings mostly go unreported and undetected by science. The fishers have contacted us with photographic evidence of these encounters.

For this expedition a small team will go to the rural fishing village and work with local fishers to catch and tag one of the most elusive and mysterious species of sharks on the planet. Working within the small window that Megamouths are accessible, we aim to collect data to study for years to come. Along with other information we will collect life history data, tissue for isotope analysis, and we will release Megamouths with 12 month satellite tags.

Almost nothing is known about Megamouth Sharks. We hope that the wealth of data we aim to collect will supply policy makers with the information they need to management this majestic species.


This looks like an incredible expedition Paul. Can't wait to follow along here. When are you heading out?

Paul, this is so exciting. Can't wait to hear more. How many Megamouths are you hoping to tag?

Thanks you guys! I am really excited. Things are happening pretty fast. The fisheries in Taiwan are starting to catch Megamouths and I am trying to get out there in two weeks. I am trying to tag 4 Megamouths during this trip. The tags will track their movement as well as depth, temp, conductivity, etc. for 18 months.

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