FRASERS DOLPHIN (T) 



Lagenodelphis hoseiFraser 1956 



Other Common Names 



Sarawak dolphin, Bornean dolphin, Fraser's porpoise. 



Description 



Fraser's dolphins reach an overall length of at least 8 feet 

 (2.4 m). They are extremely short-beaked and have a 

 pronounced dark stripe, similar to that found on the striped 

 dolphin, extending from the rostrum to the area of the anus. 

 They are robust in build and have rather small flippers and 

 dorsal fin relative to body size. The dorsal fin is slender, 

 falcate, and pointed on the tip. The body is gray on the back 

 and white on the belly. The color of the side is dominated by 

 the striping pattern. A cream-white band beginning high on 

 the rostrum extends above and past the eye, continues 

 towards the tail, and finally dissipates in the body color above 

 the anus. Just below and parallel to this cream- white band is a 

 black one extending from the area of the eye to the anus. A 

 second cream- white band below and parallel to this dark strip 

 separates the darker gray coloration of the side from the 

 white coloration of the belly. The flippers are dark above and 

 below. 



Natural History Notes 



The little that is known of the natural history and behavior 

 of the species may be summarized as follows: Fraser's 

 dolphins occur in groups of up to at least 500 animals and in 

 the Pacific are occasionally seen with spotted dolphins 

 {SteneUa attenvxita). From all accounts, they are not 

 uncommon in certain areas of the tropical Pacific and off 

 South Africa. 



Fraser's dolphins appear to be deep divers. They are 

 aggressive swimmers and, when they surface to breathe, 

 often charge to the surface, creating a spray from their heads. 

 They have also been reported leaping clear of the water. 



May Be Confused With 



Fraser's dolphin is intermediate in form between 

 Lagenorhynchus and Delphinus delphis (thus the composite 

 name Lagenodelphis). Because the species is apparently 

 limited to tropical waters, however, and because of the 

 prominent stripe on the side of the body, Fraser's dolphins 

 are more likely to be confused with the striped dolphins 

 (p. 113). The two species can be distinguished at sea by 

 several characteristics: 



Fraser's Dolphin 



Striped Dolphin 



COLORATION 



Single broad black stripe 

 from beak and eye back to 

 area of anus. 



Color dominated by series of 

 stripes from: 1) eye to anus; 

 2) eye to flipper, and 3) black 



behind dorsal fin forward, 

 towards but not reaching the 

 head. 



BEAK 



Extremely short and indis- 

 tinct. 



Longer, much more distinc- 

 tive. 



BODY SHAPE 



Slenderer. 



Robust, particularly in front 

 of dorsal fin. 



FLIPPERS 



Small, dark in color, and Longer, sometimes lighter 

 originating in light color of on upper surface; note stripe 

 sides. from front of flippers to eye. 



DORSAL FIN 



Small, slender, slightly fal- 

 cate, and pointed on top. 



Taller dorsal fin. broader at 

 base. 



Distribution 



Although Fraser's dolphins have yet to be described for 

 the western North Atlantic Ocean, they are included here as 

 "possibles" because of the recent discovery that their range is 

 far more extensive than previously known. Records to date 

 have been limited to offshore tropical waters. 



The species was first described in 1956 from the remains 

 of a beach-washed specimen from Sarawak in the South China 

 Sea. Since that time specimens have been collected from the 

 eastern tropical Pacific, and others have stranded in such 

 widely divergent localities as Australia, South Africa, and 

 Japan. Recent summaries have added sighting records from 

 the Central Pacific, near the Phoenix Island, from north- 

 west of the Galapagos Islands, and from South African 

 waters. 



Stranded Specimens 



Stranded Eraser's dolphins should be readily identifiable 

 by 1 ) distinctive coloration of the body; 2) short, indistinctive 

 beak; and 3) robust form. The only other species of small 

 dolphins with beaks of similar length and general appearance 

 are the Atlantic white-sided and white-beaked dolphins (p. 

 123 and 126); these dolphins, both with far more northerly 

 ranges, have 30-40 and 22-28 teeth in each side of each jaw, 

 respectively, while Fraser's dolphins have from 40 to 44 

 teeth in the upper jaw and from 39 to 44 in the lower jaw. 



120 



