Conservation & Science

How do you tag a jellyfish?  

They’re so soft—so squishy! Where to put a tag—and why bother? Questions like these moved scientists from the Monterey Bay Aquarium, the Monterey Bay Aquarium Research Institute (MBARI), Hopkins Marine Station and other institutions around the world to publish the first comprehensive how-to tagging paper for jellyfish researchers everywhere. This missing manual was long in the making

A wild sea nettle swims off Point Lobos near Carmel. Photo ©Bill Morgan

Tommy Knowles, a senior aquarist at Monterey Bay Aquarium, explains why.  Historically, ocean researchers demonized jellies as “blobs of goo that hurt you,” and that interfered with scientific gear. That changed in the  latter part of the 20th century as scientists grew keen to understand entire ecosystems, not just individual plants and animals. Knowing who eats what, how, where and when, they learned, is critical for conservation.

Jellyfish, however, remained a very under-appreciated member of the ecosystem for years, largely because so little was known about them.

Senior Aquarist Tommy Knowles and his colleagues work in the lab and in the filed to advance jellyfish science. Photo by Monterey Bay Aquarium/Tyson Rininger

“People didn’t know how to keep them alive in the lab or even on the boat,” says Knowles. Today, the field is coming into its own at a time when climate change has added urgency to the need to understand ecosystems in order to preserve ocean health.

A growing subject of interest

Understanding jellies is a concern for fisheries managers, too, since some jellyfish species prey upon the young and compete for food with the adults of commercially important fish. Other jellies impact tourism when blooms of stinging species foul beaches.

It’s not all negatives. We know that jellyfish play important roles in healthy marine ecosystems, by sheltering juvenile fish and crabs under their swimming bells, and nourishing hundreds of ocean predators. Jellies are a significant food source for ocean sunfish (the largest bony fish on the planet) and the endangered Pacific leatherback sea turtle, California’s state marine reptile.

A barrel jellyfish (Rhizostoma octopus) is tagged by a diver with an accelerometer using the “cable tie” method. Courtesy Sabrina Fossette/NOAA

As with other marine species that live and travel underwater—out of sight of human researchers—electronic data tags are useful tools for tracking jellies’ movements. Which gets back to the question: Just how do you tag a jellyfish? Read more…

Dispatch from the Sea of Japan: Tuna tagging 101

The Conservation & Science team at the Monterey Bay Aquarium has worked for more than two decades to understand and recover bluefin tuna – particularly Pacific bluefin, whose population has declined historically due to overfishing. A key piece of our efforts is tagging bluefin in the wild so we can document their migrations across ocean basins. Much of our work takes place in the Eastern Pacific, but this summer we’re partnering with Japanese colleagues to tag bluefin tuna in the Sea of Japan. Tuna Research and Conservation Center Research Technician Ethan Estess, working with Program Manager Chuck Farwell, is chronicling his experience in the field. This the second dispatch in his series; you can read the first here.


Estess_BigBFTUnderwater_Japan
A Pacific bluefin tuna swims in the Sea of Japan.

Before we go further into our bluefin tagging expedition in Japan, I want to share a bit of background on this fascinating and politically-charged fish we study: Thunnus orientalis, the Pacific bluefin tuna.

You may have read that bluefin are in decline due to overfishing. The challenge is to sort the headlines from the science. Scientists don’t always have perfect answers, but they do use the best data available to make educated guesses.

Read more…

Camera to crack a white shark mystery

The idea seemed like a long shot: Build a video camera that could attach to a great white shark for months at a time, withstand ocean depths of more than 3,000 feet, and sense the shark’s movements to selectively capture footage of its behavior.

But Monterey Bay Aquarium Senior Research Scientist Salvador Jorgensen, a white shark expert, thought it might have a chance if he joined forces with the talented minds at the Monterey Bay Aquarium Research Institute (MBARI).

“Some of the engineering team said it was an impossible job,” MBARI Engineer Thom Maughan recalls with a smile. “But I’m attracted to those opportunities.”

So Thom and Sal teamed up on a high-tech mission: to capture video footage of great white sharks in their most mysterious habitat.

Read more…

Keeping up with ocean sunfish

Mola mola are peculiar fish. Shaped like enormous shovels, they can grow to almost 10 feet long. They live throughout the global ocean and sometimes float languidly on their sides at the water’s surface. As charming as they are bizarre, they’re frequent, though temporary, visitors to the living collection at Monterey Bay Aquarium.

RW04-019
Ocean sunfish, Mola mola, on display at the Aquarium.

Because they get so large and grow so fast, molas, also known as ocean sunfish, can’t be kept permanently in the Open Sea exhibit. Senior Aquarist Michael J. Howard and his team collect molas in Monterey Bay, but return them to the wild once they reach about 6.5 feet long.

Monterey Bay Aquarium is, to our knowledge, the only public aquarium in the world that returns exhibit molas to the wild. Until recently, no one knew what became of the individuals after their release.

With the help of colleagues and electronic tracking tags, Michael is starting to get some answers, adding important data to a sparse body of knowledge about the mola’s life history and habits.

Read more…

In the belly of the beast: a shark tag’s travels

“If you were to put a Fitbit on a white shark, where would you put it?” asks Monterey Bay Aquarium research scientist Salvador Jorgensen. “The answer is in its stomach.”

Jorgensen and his colleagues are trying to learn where and when white sharks feed by using an electronic tracking device called a “Daily Diary” that works like the activity-logging Fitbit. Where a Fitbit tracks steps, the Daily Diary tracks tail beats. It also monitors changes in temperature and pressure.

Sharks are apex predators that occupy the top of the food web—but their might does not always keep them safe from human activity. And without sharks to keep prey animal populations in check, the food web could crumble. Knowing when and where sharks feed will help researchers identify places that need protection so that white sharks can have plenty of food to eat in peace.

A challenging project

Devices like the Daily Diary are a popular way to study wild animals, Jorgensen says. But attaching them to an ocean animal is challenging. It’s relatively easy to place an accelerometer on the leg of a sedated cheetah, but a shark is a whole other kettle of fish. So instead, Jorgensen and his team have the shark do what it does best: eat.

The internal tag was wrapped in whale blubber so the shark would swallow it. Photo courtesy Sal Jorgensen.
The internal tag was wrapped in whale blubber so the shark would swallow it. Data were later calibrated to align with the orientation of the shark’s body. Photo and illustration courtesy Sal Jorgensen.

In their latest study, published in the Journal of Animal Biotelemetry, the team – which includes researchers from the Aquarium, Stanford University and Montana State University – used the internal Daily Diary attached to a pop-up archival transmitter (PAT) tag to record feeding behavior in wild and captive sharks. In the wild, researchers lured white sharks to a skiff using a seal-shaped decoy. They wrapped the two internal tags in whale blubber—like putting medicine in a dog treat—and fed it to the shark.

Getting the tag back is easier than you’d think. Like owls, sharks eat their food and later regurgitate solid and indigestible materials. When the tag is regurgitated, it floats to the surface and pings its location to the research team.

What the data reveal

The stored data tell the story of shark feeding behavior. Sudden bursts of acceleration indicate that a shark is swimming fast to ambush its prey. If the shark is successful, the acceleration is followed by a measurable increase in stomach temperature.

White shark swallows a feeding tag. Photo courtesy Sal Jorgensen.
White shark swallows a feeding tag. Photo courtesy Sal Jorgensen.

Of course, that knowledge has to come from data stored on the physical tag, which isn’t always easy to retrieve from the ocean – especially if someone beats you to it.

One time, researcher Paul Kanive got a favorite shark, nicknamed “Scar Girl”, to swallow the tag. But right after he returned from his sampling trip, Kanive got a call from Jorgensen saying that Scar Girl’s tag had surfaced north of San Francisco, in Tomales Bay, and the signal was heading toward the boat ramp at Nick’s Cove. Kanive raced over and asked everyone on the dock if they had, by chance, retrieved any bright orange devices in the water.

‘Find something orange?’

Kanive noticed a man putting a kayak on his truck and asked him if he had found anything orange. “And he kind of stopped and smiled,” Kanive said. “He was like, ‘Ah, I knew that thing would get me in trouble!’”

Kanive said the kayaker was happy that he was able to help the team out but, “He was blown away that I was there asking him if he found something that nobody saw him find.” After he retrieved the tag, Kanive was able to get Scar Girl to swallow it once more.

– Cynthia McKelvey

Citation: Jorgensen SJ, Gleiss AC, Kanive PE, Chapple TK, Anderson SD, Ezcurra JM, Brandt WT, Block BA. (2015). “In the belly of the beast: resolving stomach tag data link to temperature, acceleration and feeding in white sharks (Carcharodon carcharias).” Journal of Animal Biotelemetry, December 2015, 3:52.

Better science through bubble-free diving

Many ocean animals are masters of stealth and disguise. The ability to run away and hide is invaluable when you live in a world full of watchful, nimble predators. Unfortunately for friendly scientists, some critters’ skittish demeanor can get in the way of research. In response, our dive team is employing its own stealth technology: the rebreather.

When divers use rebreathers, there's no tell-tale stream of bubbles to alert ocean animals to their presence. Photo courtesy George Z. Peterson.
When divers use rebreathers, there’s no tell-tale stream of bubbles to alert ocean animals to their presence. Photo courtesy George Z. Peterson.

Rebreathers allow divers to breathe in and out in a closed-circuit loop. Breathable air comes in through one side of the dive mask, while carbon dioxide-rich exhaled air leaves through another to be scrubbed and recycled. Along with enabling longer, deeper dives, rebreathers have another huge advantage: They’re bubble-free.

When scuba divers swim into the depths of the ocean, they breathe air through a hose attached to a tank. When they exhale, a steady stream of bubbles floats to the surface. These bubbles – an unusual feature in the ocean landscape – can cause wary ocean animals to dart into their hiding spots, evading researchers who are trying to observe them.

Divers using rebreathers capture sea otters as part of field research studies. Photo courtesy California Department of Fish and Wildlife.
Divers using rebreathers capture sea otters as part of field research studies. Photo courtesy California Department of Fish and Wildlife.

With rebreathers, divers can be much stealthier. They’re able to swim closer to animals without disturbing their daily routines.

“You can get up close and see some animal behaviors you may have never seen before,” said George Z. Peterson, director of dive programs at the aquarium.

Some of our divers have been using rebreathers since 2007, mostly to aid with sea otter captures that are part of our collaborative research to tag and track otters in the wild. But George is excited about the technology’s potential use with other research and husbandry projects.

It might be easier to observe skittish animals like harbor seals. Photo ©Peter Bridson.
It might be easier to observe skittish animals like harbor seals. Photo ©Peter Bridson.

For scientists, rebreathers may offer a more accurate glimpse into a day in the life of a rockfish or a crab. It may also allow for more accurate counts of animal populations in the wild. Our Conservation Research team thinks rebreathers may allow for easier observation of extremely mobile animals like seals.

Many observational studies of underwater animals are carried out using remotely operated vehicles (ROVs). While these machines aren’t very obtrusive to the animals, they’re still cumbersome to operate. In contrast, skilled divers are quite agile in the water.

By using rebreathers, divers hope to observe behavior of rockfishes and other animals without disturbing them. Photo © Bill Morgan.
By using rebreathers, divers hope to observe behavior of rockfishes and other animals without disturbing them. Photo © Bill Morgan.

George said our Husbandry staff is excited about using rebreathers to observe animal behavior in the wild so that they can better recreate their environments in our exhibits. When exhibits are more hospitable, the animals are healthier.

Since rebreathers also allow divers to go deeper than they could using traditional scuba gear, our team may get some up-close and personal views of animals only seen by scientists using ROVs. It’s possible, though unlikely, that the stealth technology will even allow divers to observe some animals for the first time.

“It’s a really neat way to observe animals in their natural habitat,” George said. He’s looking forward to even more bubble-free diving in the near future.

– Cynthia McKelvey

%d bloggers like this: