SEA 



SCIENCE 



Dolphins that frequent sounds often have distinct dorsal fins. 



number of dolphins that died and what effect 

 that had on the population." 



Previous NMFS surveys had relied on 

 aerial counts and did not include inshore waters 

 — despite evidence that many dolphins inhabit 

 bays, sounds and estuaries during summer 

 months, according to Read. 



Aerial surveys are not practical over 

 inshore waters because of the complexity of the 

 water systems and the murkiness that cuts 

 down on visibility. And individual dolphins 

 cannot be identified from the air, Urian says. 



STUDY FUNDAMENTALS 



Three boats were used simultaneously in 

 northern, central and southern regions. Each 

 vessel was to have a photographer, data 

 recorder and skipper. "Out on the water, 

 everybody did everything," Urian says. 

 Photographs were taken with 35-mm cameras 

 with 300-mm lenses. 



Danielle Waples 



At the Duke Marine Lab, 

 Urian pulls a ring binder full of 

 slides from a shelf of others just 

 like it. About three inches thick at 

 the spine, each represents one 

 day's work. Duke research 

 assistant Danielle Waples and 

 graduate student Leigh Torres, 

 who also participated in the 

 study, work nearby while Urian 

 points out slides showing distinct 

 notches on dorsal fins. 



Waples had the arduous 

 task of sorting through over 

 7,500 slides, eliminating those of 

 poor quality. The remaining 

 3,457 slides were independently 

 graded by both Urian and 

 Waples, who compared ratings 

 according to a precise protocol 

 established by Urian for the mid- 

 Atlantic bottlenose dolphin 

 catalog. 



Subjectivity in identification 

 was mimmized by the use of a computer 

 program from the University of Texas 

 Medical Branch called Finscan. Each 

 qualifying slide was digitally scanned, and the 

 dorsal fins traced. 



The final call on identity, however, is a 

 human one. Identifying dorsal fin markings 

 requires skill in pattern recognition, Urian 

 says. And after identifying more than 1 100 

 individual dolphins, a sense of humor can't 

 hurt either. "They have names," she says, 

 laughing. 



At naming parties with undergraduates, 

 dolphins got names like "Jay Leno" and 

 "Elvis" because of the profiles their dorsal 

 notches resemble. And then there's "Bugs," 

 for unknown reasons. 



When all the data was in, 1,154 dolphins 

 were estimated to inhabit North Carolinas 

 inshore waters in July 2000. Prior to this study, 

 the minimum population estimate for the East 



While some people pay good money to go Coast from New Jersey to central Florida was 

 on "dolphin watches," this was definitely work. 2,482. 



The final report acknowledges researchers 

 enduring storms, isolation and greenheads — 

 deer flies, Foster explains — in the north, and 

 "long stretches with no sightings" in the south. 



Besides the large number of dolphins, the 

 researchers found evidence that more than one 

 population of dolphins exists rather than just 

 one as was previously thought Urian says 



studies like this one can help point out "hot 

 spots" where dolphin interactions with 

 humans can cause problems. 



Single populations have genetic factors 

 in common, Read says, even though 

 individual dolphins may travel outside a 

 group. Urian adds that some dolphin 

 populations seem to have more "site fidelity" 

 than others do. This has important implica- 

 tions for fisheries management. 



JJ a small population exists in an area 

 where fishing pressure is particularly intense, 

 then an entire population could be wiped out 

 Read explains. Identifying populations can 

 help make fishery regulations more site- 

 specific, protecting the species "without 

 burdening fishermen with unnecessary 

 restrictions" in other areas, he adds. 



Read says NMFS is very interested in the 

 findings of the study. In a summary of the 

 project the researchers write, "We hope that 

 our results will form a benchmark against 

 which future monitoring efforts may be 

 measured." m 



GUIDE TO MARINE MAMMALS 

 AND TURTLES AVAILABLE 



Rhode Island Sea Grant won a 2000 

 National Outdoor Book Award for its 

 outstanding Guide to Marine Mammals and 

 Turtles of the U.S. Atlantic and Gulf of 

 Mexico. 



The 114-page guide is a compact 

 compendium of useful information for 

 ocean-goers or anyone curious about 

 cetaceans (whales, dolphins and por- 

 poises), seals and manatee, and sea turtles. 



Each entry has color illustrations, 

 maps showing species distribution and a 

 fact list with physical, behavioral and 

 abundance data. 



And, since many encounters with sea 

 mammals are brief and at some distance, 

 profiles are provided of both the featured 

 species and others with which it can be 

 confused. The sea turtle section has details 

 of head, surface and shell outlines. 



Single copies cost $25. Send a check 

 to North Carolina Sea Grant, NCSU Box 

 8605, Raleigh, NC 27695-8605 or call 919/ 

 515-9101. 



COASTWATCH 29 



