Sharks, rays & turtles
Green turtles resting on Apra Harbor’s reefs, blacktips in the shallows of Tumon Bay, eagle rays, a small and closely watched manta population, and spinner dolphins off the west coast.
Background photo: Megan Applegate (Palau)
Sharks
Mostly occasional on Guam
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: A slender body, a broad flat head, tube-like nasal flaps and white tips on the first dorsal fin and the upper lobe of the tail (Wikipedia).
At Guam: Reported at Cocos Island (Stars and Stripes Guam) and in Tumon Bay (Tim Rock, DivePhotoGuide).
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: Prominent black tips on the fins, especially the first dorsal fin and the tail; prefers shallow water (Wikipedia).
At Guam: Young and adult blacktips are seen in Tumon Bay and in Piti Bay (Tim Rock, DivePhotoGuide), and at Blue Hole (Guam Dive Guide).
Endangered on the IUCN Red List (Wikipedia).
Key marks: A stocky grey body with a long, blunt snout (Wikipedia).
At Guam: Recorded around Guam on baited underwater video in 2015 (GuamReefLife). Dive guides report unnamed “reef sharks” at 11-Mile Reef, Shark’s Pit and Blue Hole (Guam Visitors Bureau; Stars and Stripes Guam); the Guam Visitors Bureau calls reef sharks occasional (Guam Visitors Bureau).
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: A broad, flat head and two long barbels at the nostrils (Wikipedia).
At Guam: Nurse sharks are reported at Gab Gab and Gab Gab II in Apra Harbor and in Tumon Bay (Tim Rock, DivePhotoGuide; Guam Visitors Bureau; Stars and Stripes Guam).
Whale sharks and hammerheads have been seen now and then at Blue Hole (Scuba Diving; Guam Visitors Bureau), and tiger sharks and silvertips have been recorded around Guam (GuamReefLife).
Rays
Over sand and along the reef edge
Endangered on the IUCN Red List (Wikipedia). The Indo-Pacific population was split from the spotted eagle ray, A. narinari (Wikipedia).
Key marks: A dark green-grey to blackish back covered in white spots, and a long tail (Wikipedia).
At Guam: Spotted eagle rays at Cocos Island (Stars and Stripes Guam); eagle rays, young ones too, in Tumon Bay, Piti and Agat Bay (Tim Rock, DivePhotoGuide), and at Blue Hole (Guam Visitors Bureau).
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: Cephalic fins in front of a wide, forward-facing mouth; usually 3–3.5 m across (Wikipedia).
At Guam: Seen at Gun Beach and in Tumon Bay (Tim Rock, DivePhotoGuide). Guam’s mantas are few: the Micronesian Conservation Coalition has identified 53 individuals in 10 years (Pacific Island Times).
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: A thick, round disc, often marbled (Wikipedia).
At Guam: Marbled rays are seen in Tumon Bay and at Piti, along with pink whiprays (Tim Rock, DivePhotoGuide).
Give mantas room
Guam’s small manta population is disturbed by growing human traffic. The Micronesian Conservation Coalition asks divers and snorkellers to stay about 10 m (33 ft) away, never touch a manta and not use flash (Pacific Island Times).
Turtles
Haggan on almost every west-coast reef
CHamoru: haggan or haggan betde (Guampedia; US Fish & Wildlife Service). Least Concern on the IUCN Red List worldwide (Wikipedia), but the Central West Pacific population, which includes Guam, is listed as Endangered under the US Endangered Species Act (US Fish & Wildlife Service).
Key marks: A flattened body, a short beaked head and paddle-like flippers (Wikipedia).
At Guam: Most seen around Guam are juveniles feeding on seagrass and algae in channels, harbors and lagoons (Guampedia). Divers meet them at Gab Gab, where they rest at 12–18 m and in the shallows, in Piti Bay, at Fingers Reef, Gun Beach and in Tumon Bay (Tim Rock, DivePhotoGuide), and at Cocos Island (Stars and Stripes Guam). More than 200 nesting emergences were recorded on Guam in 2021 (University of Guam).
CHamoru: haggan karai (UOG Sea Grant). Critically Endangered on the IUCN Red List (Wikipedia).
Key marks: A narrow, pointed, hawk-like beak and an amber shell with dark streaks (Wikipedia).
At Guam: Native to Guam (UOG Sea Grant). Seen in Piti Bay (Tim Rock, DivePhotoGuide) and at Gab Gab II (Guam Visitors Bureau); reported less often than green turtles.
Green turtles were listed as endangered by the United States in 1978, and Guam passed its own Endangered Species Act a year later (Guampedia). Volunteers watch the nesting beaches in the Haggan Watch programme, which began in 2005 (US Fish & Wildlife Service).
Turtle manners
Don’t chase, touch or ride turtles, and leave a resting turtle room to swim up for air.
Dolphins
On the boat ride out
CHamoru: tuninos, for dolphins (Guampedia). Protected under the US Marine Mammal Protection Act (Guampedia).
Key marks: Small and slim, with a long beak, three-tone grey colouring and spinning leaps (Wikipedia).
At Guam: Guam’s resident dolphin, on the sheltered west side: at Double Reef, Agat Bay, Bile Bay and Merizo Bay. Pods of 20–200 rest by day over shallow, clear, sandy water and feed offshore at night (Guampedia). Also seen on the boat ride to 11-Mile Reef (Guam Dive Guide).
Short-finned pilot whales, in schools of 25–50, have been recorded near Urunao and Togcha (Guampedia), and are reported at Blue Hole and Shark’s Pit (Guam Visitors Bureau). Sperm whales have been seen off Agat, and bottlenose dolphins at Blue Hole (Tim Rock, DivePhotoGuide).
Credits
Where the photos come from
None of the photos on this page were taken at Guam. They are Megan Applegate’s photos of the same species in Palau, Socorro and Cocos Island, as each credit says; the other animals link to photos online.
| Species | Photographer | Licence | Source |
|---|---|---|---|
| Whitetip reef shark | Megan Applegate | © Megan Applegate, all rights reserved | Photographer's own photo, taken at Socorro, Mexico, December 2023 |
| Grey reef shark | Megan Applegate | © Megan Applegate, all rights reserved | Photographer's own photo, taken at Palau, January 2023 |
| Round ribbontail ray | Megan Applegate | © Megan Applegate, all rights reserved | Photographer's own photo, taken at Cocos Island, Costa Rica, August 2024 |
| Hawksbill turtle | Megan Applegate | © Megan Applegate, all rights reserved | Photographer's own photo, taken at Palau, January 2023 |