Tuesday, Nov 25, 2014

Project tracks bay's bottlenose population

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Published:   |   Updated: June 21, 2014 at 09:14 PM

The half-dozen bottlenose dolphins off the bow appeared to be swimming apart, so marine science professor Shannon Gowans halted the pursuit and pointed skipper Emily Sullivan in another direction.

“Nikki, are you good?” Gowans shouted to Nikki Szlamnik, who cradled a Canon camera with a foot-long zoom lens.

Nodding, Szlamnik replied, “I think I got a good one of each one.”

The trio were participating in a summer tradition known as the Eckerd College Dolphin Project, an ongoing research effort to track, photograph and identify the dolphin population of Boca Ciega Bay.

For three hours this day, soon-to-be sophomore Sullivan steered the 19-foot Cape Horn through an area that included Bunces Pass, near the bridge to Fort De Soto Park.

Szlamnik, who will be a senior this fall majoring in human development and psychology, drew the assignment of snapping close-ups of every dorsal fin that slid out of the water.

That's the key to the project — a good digital image of one unique marker that sets apart what appear to be indistinguishable mammals.

Experts such as Gowans can identify individual dolphins based on gashes from boat propellers, sharks and fishing entanglement, tiny nicks and deformations, and normal wear and tear in the cartilage that makes up the fin.

And with the help of recognition software developed at Eckerd, the chore of comparing thousands of images has become a lot easier.

On a bench in the Galbraith Marine Science Laboratory at Eckerd, Gowans pulled up a photo from a recent sighting on a computer monitor and zoomed in on a dorsal fin of a dolphin arcing through the bay's surface.

She made a few clicks to create a digital outline of the fin and, with another click, a complicated algorithm took over to compare the image with 881 dorsal fins in Eckerd's catalog.

The software, DARWIN — for Digital Analysis and Recognition of Whale Images on the Network — was developed by Eckerd's computer science department with input from the Dolphin Project. The software ranked potential matches.

“This is our match window,” Gowans said, gesturing to a list the computer soon provided. “But it still comes down to a person going through and saying, 'Is this the right one, or not?' ”

Gowans made a visual match with one of the recommendations and concluded that the dolphin is indeed already in the system, coded SMHK and nicknamed “Small High Nick” for a feature on its dorsal fin.

On the boat, the crew had registered when and where Nick was spotted, along with the water and atmospheric conditions and other information. That data were logged alongside information on Tinsel, Hangin' Twenty, Zim Zam and the others in the system.

Gowans called up a photo of dolphin who's a regular in these parts to show her distinctive heart-shaped dorsal fin, caused by an unknown injury. Cupid had just been spotted hours earlier.

The project discovers about 10 or 15 dolphins a year that haven't been seen before.

Gowans has been running the Eckerd College Dolphin Project since coming to the school in 2004 — a predecessor launched it in 1993 — and she says she has a “reasonable handle” on about 100 dolphin residents that stay in the Boca Ciega Bay area year-round.

The region is roughly the waters from the Intercoastal Waterway in the Gulfport area south to the mouth of Tampa Bay, including the region around Tierra Verde and Fort De Soto Park. During the summer, 400 dolphins may be swimming across all of Tampa Bay.

Scientists doing teeth analyses have concluded that dolphins can live as long as 60 years, though the typical lifespan is thought to be in the 30s and 40s.

Gowans sighted a fungal infection on the dorsal fin of a dolphin first photographed by another researcher in 1971. Another dolphin, DMBK, or Double Mid Buck, was first photographed in 1988 and has been seen every summer since 1993, this year included.

The Eckerd professor laughs when she recalls the early days of compiling binder after binder of black-and-white negatives and box after box of slides. Comparisons were made by flipping through hundreds of pages of images. “Digital is unbelievably easier,” she said.

But the work on the water hasn't changed.

“The advantage is that we don't have to touch them to do anything,” Gowans said. “We can track them. We can follow them. We can photograph them.”

That's something the public is not allowed to do.

Boaters and beachgoers snap photos of the sea creatures as they pass, but bottlenose dolphins are covered under the Marine Mammal Protection Act, and the eastern Gulf of Mexico coastal stock has been classified as “strategic.”

It is illegal to harass dolphins, with harassment defined as any act of pursuit, torment or annoyance.

The Eckerd team is allowed to conduct its research under a permit, LOC No. 15512, issued by the National Marine Fisheries Service. Such permits are so restrictive that Eckerd was required to seek permission from the National Oceanic and Atmospheric Administration to allow a news team on board.

On the bay, with Szlamnik snapping away and Sullivan keeping one eye on a depth finder as she navigated the shallow water, Gowans pointed to a dolphin engaged in lobtailing. That's the hard slamming of the tail on the surface that makes a deep ker-plunk sound; it's believed to be a means of communication.

The team has documented fishwhacking, where a dolphin flips a fish into the air with its tail, stunning the prey as it falls back to the surface for an easy meal.

The Eckerd group is working with a similar project at Mote Marine Laboratory in Sarasota, which has identified 7,000 individual dolphins from Tampa Bay to Charlotte Harbor. Gowans hopes to involve researchers from around the Gulf of Mexico to establish a cooperative, Gulf-wide effort to identify and track dolphins.

The Eckerd software is open-source and is distributed free over the Internet for use by scientists around the world. The college's research is providing valuable information about bottlenose dolphin biology — their population, how long they live, their range.

It is also raising questions. Why have many of the local dolphins declined to swim to even Sarasota, while others stray far away? What would happen in the case of an oil spill, perhaps one that would have a more severe impact on the Tampa Bay area than the BP spill? What will happen when the chemicals involved in the BP spill start making their way up the food chain?

“We've got the basic biology piece,” Gowans said. “We have a terrific baseline should something happen.”

And the project is fulfilling another key goal: giving undergraduates a hands-on role in field research, literature review and scientific writing, not to mention piloting a powerboat and operating a high-end camera for research purposes.

Many Eckerd Dolphin Project alumni have continued graduate research in the field or are working in key positions at Mote, NOAA or other agencies.

And it has built bonds between the researchers and their subjects, whether they are involved for a summer or, in Gowans' case, for a decade.

“If we haven't seen some of those really identifiable ones for a spell, we're a little nervous that they might have died,” she said. “What happened to them? Where have they gone? There was a spell where we didn't see that dolphin Cupid for a couple of months, and that's rare for her. We didn't know where she went.

“This is one of those where it does become personal.”

 

jstockfisch@tampatrib.com

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