By Lee Anna Sherman
A dolphin’s dorsal fin can be as distinctive as a human fingerprint. As the fin slices through the sea, its unique pattern of pigments, nicks and scars relays the animal’s personal story to observers on the surface. Often, scientists can use these markings to ID individual dolphins. But for some species, fin IDs are not precise enough. That’s why researchers like Oregon State University Ph.D. student Rebecca Hamner have turned to DNA.
Several summers ago in Australia’s Shark Bay, Hamner learned to recognize 200 distinct dorsal fins on bottlenose dolphins with names like Puck, Noggin and Tool. Their scars recorded entanglements with fishing nets, skirmishes with tiger sharks and battles among themselves for mates — personalized markings she quickly came to know around the resort town of Monkey Mia as a field assistant for two professors from the University of Massachusetts Dartmouth and the University of Zurich.
At Monkey Mia, fin ID was a piece of cake. “Ninety percent of the dolphins in Shark Bay have shark bites or other distinguishing scars,” notes Hamner, a student in OSU’s Marine Mammal Institute.
But then she won a Fulbright Scholarship to study the endangered Hector’s dolphin of New Zealand, which Scientific American’s “Extinction Watch” blog calls the “world’s smallest and rarest dolphins.” She joined the international research team of Scott Baker (who has appointments at both the University of Auckland and OSU’s Marine Mammal Institute) and began investigating the population structure of the Hector’s, which is about one-third the size of a bottlenose with a distinctive black mask and rounded dorsal fins. This time, she ID’d the animals by collecting tiny skin samples using a modified veterinary capture rifle to fire a floating biopsy dart from a boat.
Scouting for Scientists
So how did Hamner wind up studying dolphin genetics at the internationally known OSU Cetacean Conservation and Genomics Lab? Turns out, it had more to do with Hamner’s tenaciously tracking down faculty members who needed research assistants than with a burning passion for marine mammals per se. One research topic led to another — from dolphins to microalgae to invasive seaweed to lionfish and, finally, back to dolphins.
Her path to marine mammal expertise began in North Carolina, where she grew up tent camping at Lake Jeanette, tramping the woods, stalking wildlife behind the family home and splashing in the Atlantic Ocean on summer beach trips. When she started college at the University of North Carolina Wilmington, she knew she wanted to do “something with animals and nature.”
She wasted no time getting started. It was only her second week as an undergrad double-majoring in marine biology and psychology when she approached a dolphin researcher, who quickly put her to work doing photo-ID and acoustic surveys for bottlenoses along the North Carolina coast.
“I worked on those surveys every weekend for four years,” Hamner says. “That’s where I got my passion for field work.”
Species Spin
Meanwhile, during her second semester, she met a professor who was identifying microalgae by DNA sequencing. “Hmm,” she thought, “genetics is kind of interesting.” After working with him on the unicellular species (“these little green dots that you need a microscope to see”), she was recommended for a paid position with the researcher next door. So she switched to studying invasive red seaweed called Gracilaria vermiculophylla. When she was asked to process a few invasive lionfish samples sent over by one of the researcher’s collaborators, a National Oceanic and Atmospheric Administration scientist in Beaufort (home of the Rachel Carson Coastal Preserve), she was captivated. For the next three years, she studied the venomous fish and presented her findings in her honors thesis.
After graduation, Hamner circled back to dolphins, heading first to Shark Bay for that finny summer and then on to New Zealand. After collecting tissue and analyzing DNA from the Hector’s dolphins and comparing it against existing samples in the Cetacean Tissue Archive at the University of Auckland, the team documented an alarmingly low abundance for the subspecies called the Maui’s dolphin.
“Suddenly, I was being invited to be a scientific panel member at a risk-assessment meeting organized by the New Zealand Department of Conservation and Ministry of Primary Industries,” Hamner says, her tone a mixture of pride and surprise. Her work with Baker has spurred the New Zealand government to reevaluate current protections and extend fishing restrictions along the coastline they inhabit. “Because of our findings, the Maui’s Dolphin Threat Management Plan is being accelerated.”
With only about 55 remaining individuals over the age of 1, the stakes couldn’t be higher.
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