Researchers Study 

 Bottlenoses 



Bottlenose dolphins are common 

 in North Carolina, particularly in the 

 fall, when clusters of their shiny steel- 

 gray dorsal fins can be seen cresting 

 the water as they journey toward 

 warmer zones. 



Even though dolphins are highly 

 visible, scientists say research on the 

 bottlenose in North Carolina had 

 been limited until July of this year. 

 That's when 54 scientists converged 

 along the coast for a 1 2-day live 

 capture project sponsored by the 

 National Marine Fisheries Service. 



"It was the first time dolphins 

 had ever been captured for scientific 

 research in North Carolina," says 

 Gail Cannon, Duke biologist and 

 participant in the project. "We were 

 very happy with the results." 



Thirty-one dolphins were 

 captured, studied, tagged and 

 released with the goal of assessing the 

 health of the population, as well as 

 trying to understand their migrational 

 patterns. 



Prior to the project, state 

 researchers relied on photo identifica- 

 tion projects and data collected from 

 strandinqs to study dolphins, Cannon 

 says. Although these sources can shed 

 light on factors that underlie dolphin 

 mortality, they don't provide the 

 invaluable data of a live capture. 



"A live capture gives you a more 

 accurate look at what the animal is 

 experiencing," says Patricia Fair, 

 physiologist at the Southeast Office of 

 the National Marine Fisheries Service 

 (NMFS) in Charleston, S.C., and 

 project participant. 



Because the body tissue of a 

 dead stranded animal is often 

 degraded, it's sometimes difficult to 

 take correct measurements and gather 

 other types of information, she says. 



In the NMFS project, basic data 

 were collected and dolphins were 

 tagged by suction cup or with small 

 pins in the dorsal fin. Others were 

 tagged with radio tags, so they could 

 be tracked over the airwaves. No 

 permanent tags were used in the one- 

 time project. 



A pod of dolphins becomes airborne. 



a Dolphin Behavior 



lY variety of dolphin species their body temperatui 



rety of dolphin species 

 roams North Carolina's waters, but the 

 bottlenose is the species most often 

 seen from the beach. Other types of 

 dolphins found in the state include 

 spotted, spinner, striped, rough- 

 toothed and Risso's dolphins. Some 

 locals mistakenly call these mammals 

 porpoises. 



Real porpoises are usually found 

 in colder waters to the north, although 

 they occasionally stray south. The 

 harbor porpoise is the most common 

 porpoise species documented on the 

 East Coast. It is beakless and smaller 

 than a dolphin — about 5 feet long — 

 with a dark brown, black or dark gray 

 body and a light-colored underside. 

 Harbor porpoises tend to stay in 

 shallow coastal waters, rarely swim- 

 ming into the deep sea. 



Bottlenose dolphins grow seven 

 to 12 feet long, cruising through the 

 water at speeds up to 20 mph. Their 

 bodies are streamlined by a smooth 

 casing of blubber that envelops their 

 flexible skeletons like a rubber glove. 



This dense coat of blubber allows 

 warm-blooded dolphins to maintain 



their body temperature in cold water 

 temperatures, as land mammals do with 

 hair or fur. Unlike mammals such as 

 cats or dogs, which produce large litters, 

 dolphins typically bear a single young 

 after a gestation of about 1 2 months. 



The 80 to 88 conical teeth that line 

 the dolphin's bottle-shaped beak help it 

 grab food and devour it whole. Dol- 

 phins, which mainly feed on schooling 

 prey, hunt in groups of up to 100 called 

 pods. In this way, they can search a 

 wider area for prey and can combine 

 their expertise to locate food faster. 



With a far-reaching repertoire of 

 squeaks, whistles and clicks, dolphins 

 transmit signals to each other. And 

 they navigate through an echolocation 

 system. This system — which functions 

 much like the radar system of a bat — 

 also enables the dolphin to pinpoint 

 food and explore its ocean surround- 

 ings. The conical teeth are part of the 

 receptors for echolation. 



Unlike fish, dolphins and whales 

 must periodically rise to the surface for 

 a dose of oxygen. Fish can extract 

 oxygen from water through gills, but 

 cetaceans have lungs. Through the 



1 SEPTEMBER/OCTOBER 1995 



