Bottlenose dolphins contain mysteries. She’s trying to get answers


Bottlenose dolphin – Tursiops truncatus. A dolphin surfs in the wake of a research boat on the Banana River near the Kennedy Space Center. Credit: public domain

Rain splashed over the fiberglass boat and evergreen waters as Professor Shannon Gowans walked away from Pier 6. Her students wrote down details of the time and weather in pencil: not ideal, maybe. be, for a Saturday on the bay, but what they were looking for was below the surface.

The boat picked up speed. Eckerd College grew small and the wet expanse of Boca Ciega Bay opened wide. Along the mangroves, through the canals, his three students scanned.

“There is a dolphin,” Kaitlynn Stewart said urgently.

“Let me know if you see him again,” Gowans said.

“By the sign,” said Karastyn Bennett. A silver bow curved in the water, then vanished.

Stewart prepared the camera and stood under the bimini as Gowans moved closer, then lined up with the dolphin’s path. Parallel to dolphin meant parallel to his fin, the closest thing to a badge he could wear.

The shutter has sounded.

“Ope, I got it! Said Stewart. She hoped.

The next 10 minutes passed like this: An observation. A disappearance. Guess the dolphin’s route and try to approach it.

“Do you want me to do another pass?” Said Gowans. To the rippling water, she said, “Cooperate! “

She had devoted her career to marine mammals, in particular bottlenose dolphins. These dolphins are the celebrities of aquarium billboards, the stars of luxury resorts, the reason little children dream of becoming marine biologists. They’re whistling on the Discovery Channel and looking for fish at SeaWorld. They choose the Super Bowl winners. On some sunset cruises, they are guaranteed or refunded.

Gowans was that little boy. She grew up in the Canadian prairies, but visited the Vancouver Aquarium and was captivated by whales, these large, intelligent and social creatures in an alien ecosystem.

She studied in Nova Scotia with the famous Hal Whitehead, the only person who did exactly what she hoped to do.

By now she knew as well as anyone the habits of dolphins, the way they feed and dive deep. She had learned that everyone had quirks. Some dolphins have dispersed to feed on their own, while others feed together, herding schools of fish against the dikes.

Yet despite their ubiquity, from Iceland to New Zealand, and despite all the research already done, bottlenose dolphins remain mysterious creatures.

Imagine that, she told her students. Aliens come down to study humanity, but they’re stuck in your fridge. They only see you when you open the door. From this brief flash, they must make assumptions about our species.

The world’s oldest dolphin research program began in Sarasota in 1971, the year Gowans was born. We are only now starting to follow wild dolphins throughout their lives, and we still see almost nothing of their experience.

Speaking of which, how long do wild dolphins live? Gowans wonders.

And: How many are here? Why are some vagrants and other home-seekers? When they whistle, what are they saying?

On the bay, the students prepared for the passage of a boat which knocked them over. They resumed their guard. Everyone had their passions – coral reef ecology, marine animal rehabilitation, bioacoustics – but being part of Eckerd College’s Dolphin Project had to be part of a legacy.

Gowans and her husband and colleague, Peter Simard, oversee the program, which began in 1993. Simard was also said to have been on the water, but he was on duty for the children.

Both teach — Gowans in marine science and biology, Simard in environmental studies — and in research. Gowans is interested in dolphin societies and socialization; Simard to their ecology, range and acoustics.

Students help them fill in the blanks with Tursiops truncatus. They track where dolphins meet and drift, analyze whistles, and throw parties to name new additions. (Think “Nick Jagger” and “Ice Cream Scoop.”) They’re posting research on a species that, as a top predator, is a sentinel for the health of the whole bay.

If we lose these dike feeders, we lose something of our ecosystem.

For Gowans, a lot of the work comes down to this: Understanding dolphins helps us protect them.

The boat left a green churn in the bay window. Pelicans rested on channel markers. The Don CeSar stood at the end of the bay.

Gowans slowed down for another sighting. Meher Datta, who is called Nemo, was squatting in red rubber Birkenstocks. She needed a quick hand to capture the telltale details of the fin: the shark bite marks, the scars left by fishing gear, the natural tears in the dorsal cartilage.

Later, those details would reveal whether it was a familiar dolphin – one of over 1,000 dolphins in their digital catalog – or a new addition.

Click, click, click. Bennett wrote down the time and coordinates.

Gowans pulled the hydrophone out of his bin, essentially a microphone hanging 6 feet under a floating foam ball. Stewart wound his long black rope behind the boat, where the seaweed stirred.

Nearby, cars and large platforms roared towards the Sunshine Skyway. The dolphin slipped into the calm, where the hydrophone recorded. Would a lone dolphin make a noise?

They would listen later. Much of Simard’s work explores how dolphins use sounds, whether to find food, navigate, or ‘talk’. For years scientists have considered certain whistles to be distress calls, but now “signature whistles” seem to be the rough equivalent of a dolphin calling out its name. While whales share click patterns, much like regional clans, dolphins are very individual. In class, Gowans explained, “Instead of saying, ‘I’m a Gowans, are there Gowans out there?’ it’s more, ‘I’m Shannon!’ “

Further research at Eckerd has shown that, as boats pass, dolphins change their hissing frequency to be heard above the roar.

A passive listening station on the college platform helped capture the sounds of dolphins, until it was toasted in a summer thunderstorm. A replacement is in preparation.

For now, the lone dolphin has stood up and huffed, pushing air through its vent.

“Do you think you have any? Gowans asked Datta. They pushed further on, where dark clouds gnawed the hazy sky.

Students had loads of homework waiting for them in their dorms, but working with the Dolphin Project was somewhere between work and play. Especially when it came to babies.

Days like this have allowed them to attend “social balls,” like the time Bennett saw two groups converge and play, roll over and show their bellies. Or the time they saw calves so new that their skin was wrinkled because they were in utero.

A little further down the bay, they spotted another, and a much smaller one. Likely born this year, Gowans said. Then the dolphins continued to surface.

“Air!” someone shouted.

” A stroke of luck ! They had taken turns filling out observation sheets, and now it was a flurry of activity. The mothers swam with their calves, snapping tails against the surface.

Small fish jumped out of the water, a good sign that it was snack time. A disconnected dolphin — floating on top of the water to rest.

As the students turned from observation to observation, the clouds darkened. Gowans called to return to the docks.

Halfway, she cut the speed. In the warm, still canal, a dolphin tour boat had stopped. The tourists held cameras, fixed on the water.

“I think Cupid has a new baby! said Gowans.

Cupid, first added to the catalog in 1997, spotted over a hundred times, wears telltale notches on its heart-shaped fin. Gowans would know her anywhere.

Next to Cupid, a calf stood up halfway across the bay and slumped onto his chin, perhaps trying to get a glimpse of the world from above. The students screamed.

Cupid is his own mystery. Some dolphins swim along California. Cupid never, as far as they know, swam for a day to Sarasota.

The boat turned around. Cupid floated for a minute, then slipped underneath.


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Quote: Bottlenose dolphins contain mysteries. She tries to get answers (2021, November 29) retrieved on November 29, 2021 from https://phys.org/news/2021-11-bottlenose-dolphins-mysteries.html

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