Tag Archives: feeding

Beverly’s feast

2015_04_10

Well, my prediction that Beverly would turn suddenly down to the nesting beach was wrong. She is still hanging off the Azores, and not heading to Trinidad. The reason I’d been so sure she might go to a beach there was because she had been recorded nesting in Trinidad before—and the last time was in 2013.

Most leatherbacks in the western Atlantic nest every two to three years. The majority nests every two years (hence, my assumptions about Beverly). The time between nesting years is called the “remigration interval,” and it varies, sometimes by many years. Pacific leatherbacks, for example, have remigration intervals that are closer to four years.

Scientists think the remigration interval reflects the amount of food a turtle finds on her migration. The interval is the time it takes the leatherback to eat enough to generate the energy required to migrate back to the breeding ground and reproduce.

“It’s not surprising that she’s not remigrating,” says Canadian sea turtle expert Dr. Mike James. “What is interesting is that Beverly is so far north. She must have found an abundant food resource because she’s stayed in the same area for months, which is unusual. I imagine she’s good and fat by now. I’m curious to see in the next few months what she does—whether she goes back to the slope waters off Canada, or whether she does what none of our tagged animals has done before, and goes east.”

If Beverly does head back into Canadian waters, maybe we’ll find her again up here this summer.

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Turtle-cam: Life from a leatherback’s perspective

This is a look at life from a leatherback’s point of view. That is the top of the leatherback’s head you see in the foreground, with a jellyfish just beyond it.

To us this video is amazing and fascinating.

It was taken using a camera attached to the shell of a leatherback turtle. Dr. Mike James, who is the CSTN’s scientific advisor, developed this camera in collaboration with engineers at Xeos Technologies and Soko Technologies. They called it Serrano-V.

A scientific paper published today of which Mike is a co-author talks about what we’ve learned with the help of Serrano-V and why it is so critical to the conservation of leatherbacks.

As you know, we collect data about leatherbacks using satellite transmitters. This data is “coarse.” It doesn’t get into the fine details of what the leatherbacks are doing because it is limited by the amount and type of data you can transmit through the bandwidth of the system of satellites used to monitor the tags.

Serrano-V allowed us to collect the finest-scale behavioural data currently available for leatherback turtles while simultaneously recording video from a camera mounted on the turtle’s shell. Dr. Bryan Wallace, who is a co-author on the paper, says “it’s like getting turtle’s home videos—seeing what they see, where they go, and how they acquire vital resources to fuel their natural behaviour.”

It is just the kind of information we need to work at conserving leatherbacks in the most intelligent way possible. “Rather than inferring what the turtles are doing below the surface of the water, we can actually see it happening,” says Mike.

Bryan Wallace (left) and Mike James (right) on the turtle boat off Nova Scotia.

Bryan Wallace (left) and Mike James (right) on the turtle boat off Nova Scotia.

The paper is really exciting for us—and particularly because Bryan and Michael Zolkewitz, the other co-author, are tremendous scientists who are as enthusiastic about this work as we are.

What that paper can’t tell you, however, is how hard it was to get this to work. This represents years of trial and error. (The project began almost a decade ago while Mike was finishing his post-doc!) There were growing pains typical of refining such a cutting-edge instrument…inevitably, sometimes the camera didn’t record or a sensor needed to be replaced. The camera system was also subjected to tough conditions at sea. You can imagine the impact of pounding waves, of the force of water as the turtle swam and dove. There were hours of video that couldn’t be included in the analysis because the camera had shifted from its original position on the turtle’s shell and the field of view we needed wasn’t captured.

Mike used to rest Serrano-V on an old white pillow in the hold of the boat to protect it from being jostled and damaged when it wasn’t in use. And then when it was, he would emerge from below deck, carefully balancing Serrano-V, still on its pillow. He’d climb along the side of the boat, bending under the stay wires to stand up on the bow, calling for everyone to stand back to protect the delicate antennas. It was always funny—but serious, too. There was only ever one Serrano-V. There was no replacement available. And we all knew how much value the study would have if it worked.

I love the feeding video. It’s spectacular. It seems to me such a privilege to have the chance to see what the leatherbacks are up to—to be humans allowed in that private world of theirs.

But I love this video, too. This one is from the early days of Serrano-V. You can see it on the turtle. It is slipping slightly. What is most important to me is the conversation you hear. Those are the voices of Mike and Blair and Bert Fricker, who are two of the fishermen we have worked with the longest. Blair is the captain of our field boat off Cape Breton. You can briefly hear Martin, who worked on our field team for years, and a little of me. Everyone is suggesting ways to make the tag work better. The success we are celebrating with this paper is the result of dozens and dozens of conversations like this one—of lots of minds working out the small details of a big question. The value of a strong team of dedicated people.

The other thing that a paper can’t represent properly is that moment when a scientist, faced with needing information that can’t be collected because of the limits of technology becomes determined to find a way to make that technology. That to me is also remarkable. That is magic. That is art as much as painting or dancing or writing. It takes courage to create something that wasn’t there and courage to be tenacious season after season even in the face of a lot of “failure.” It takes a great team and the ability to inspire them. So cheers to you, Mike James—and to all the people who helped—fishermen, biologists, engineers, CSTN staff. And thanks.

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Heading south-ish

2014_11_04_Map

These turtles are not in a hurry. They’re starting their migration to the nesting grounds, but they aren’t definitively swimming south yet. Asha, as you can see from her detailed track below, started south, and then looped up again back onto the shelf break. At this point, she is foraging on jellies as she travels and likely found a patch of them. We’ve seen leatherbacks do this many times before.2014_11_04_Asha

Christie and Beverly have tracks that are a bit more unusual.

Christie is still hanging out in the northern foraging domain. She hasn’t decided to head out yet. When she does, we’ll see her covering long distances relatively quickly. Right now, she is near the Virgin Rocks on the Grand Banks. The water there at this time of year is under the strong influence of the Gulf Stream, so is certainly warm enough for her.

Beverly is particularly interesting. We’ve seen lots of leatherbacks head far to the east—almost to the African continent—before turning back west to the nesting grounds on this side of the Atlantic. However, we’ve never seen a leatherback go this far east while at a latitude this far north. Beverly is 400 km southeast of the Flemmish Cap—in territory “our” Canadian leatherbacks haven’t covered before.

This is one of the reasons I find satellite tracks of leatherbacks so fascinating. Although we’ve satellite tagged 86 turtles, there is always something new to learn. The leatherbacks surprise us.

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On the fast track

You might wonder, looking at this map, how it’s possible we expect this race to last into the spring. We all have to admit that Mignonnette is motoring. We are pretty certain she’s headed toward French Guiana. When we tagged her at the beginning of August off Cape Breton Island, our team found a French Guiana PIT in her shoulder muscle. PIT stands for “passive integrated transponder.” PITs are the same microchips that your Mignonnettevet might use to mark your dog or cat. Researchers implant them in leatherbacks’ shoulder muscles as a way of identifying individual animals.

But despite her speed at this point, Mignonnette won’t haul up on a beach anytime soon. None of these leatherbacks is likely to nest earlier than March. Bulked up on Canadian jellies, they cover incredible distances in a relatively short timeframe before reaching waters off the nesting beaches, where they’ll hang out again to feed.

This is a photo of Mignonnette that Devan, our turtle technician, took when we satellite tagged her.

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The Canadian buffet

Canadian waters are an all-you-can-eat jellyfish buffet for leatherback turtles. Atlantic leatherbacks migrate to Canada to feed on jellies. One way you can see this is by looking at their tracks. Check out the mess of spaghetti up around Atlantic Canada. Those meandering tracks show turtles foraging for months in our jellyfish-dense waters, growing fatter and fatter. Riley, whom we talked about last post, is doing something similar off New England.

And then, like clockwork, in mid- to late October, they’re done. They leave Canadian waters, and the tracks lengthen out considerably, as you can see here. Now the animals are in “migration” mode—on their way south. They’ll still eat jellies when they can find them. But you won’t see them settle in and stay like they do in Canada again until they reach the waters off the nesting beaches.

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