Pantropical Spotted Dolphin -- Cetacean Info at Whale Songs

SCIENTIFIC NAME: Stenella attenuata

COMMON NAME: Pantropical Spotted Dolphin


* Distribution not continuous within the range, though it appears to be abundant in many areas
* Well-studied in the eastern tropical Pacific but poorly known elsewhere
* Overlaps with the Atlantic Spotted Dolphin, mainly in the western North Atlantic, where it occurs offshore
* No known migrations, though offshore form may make seasonal movements, usually summering inshore and wintering offshore


* Dark gray cape
* Dark line from flipper to beak
* Tall, falcate fin
* Slender, elongated body
* Long narrow beak
* White-tipped beak and "lips"
* Most adults heavily spotted
* Appearance varies within school
* Spotting varies with age and location
* Spots increase in size and number with age



* Widely distributed, mainly in the tropical, subtropical, and temperate waters of the Atlantic, Pacific, and Indian Oceans
* Found mainly where surface water temperature higher than 77 degrees (25 degrees C)
* Commonly occurs around island


* Stomach contents of recorded dolphins include a large number of small epipelagic and mesopelagic fish and cephalopod species, nemerten worms and crab larvae
* Lactating females may feed more heavily on epipelagic fish than do pregnant females


* Average age at sexual maturity in males is 14.7 years and females mature on the average at 10-12 years, with a range of 10 to 17 years
* Maximum longevity in both sexes may exceed 45 years
* Length at birth= 0.85m in the offshore eastern tropical Pacific
* Breeding is diffusely seasonal- two to three calving seasons in the spring, autumn, and summer
* Average calving interval in the eastern Pacific= 2-3 years in the western Pacific 4-6 years


* Very active at surface
* Fast, energetic swimmer, using long, shallow leaps
* Frequently breaches
* Lobtailing and bow-riding common
* In tuna fishing areas some individuals flee from boats


* Studies have been made of the eastern tropical Pacific populations involved in the tuna purse seine fishery
* No other studies done
* Average of 2.5 million in 1981-86


* Major by-catching problems in the eastern tropical Pacific due to the habit of schooling with tuna
* Estimated that about 70,000 offshore pantropical spotted dolphins were killed during tuna purse seining in 1986 (Costa Rica, Ecuador, El Salvador, Mexico, Panama, Spain, USA, Vanuatu and Venezuela), 693 by direct catches in Japanese waters and that some were taken incidently in Australian waters- some also taken in at least the Caribbean, Sri Lanka and the Solomon Islands
* Several dolphins also killed in efforts to reduce the interference in a hook-and-line fishery for yellowtail tuna off Iki Island in Japan