Wai‘anae Ecological Characterization

Marine Mammals and Sea Turtles

The Hawaiian archipelago is home to an array of large marine animals including whales, dolphins, the endangered Hawaiian monk seal, and several species of sea turtle. The Hawaiian Islands and Northwestern Hawaiian Islands serve as foraging, nesting, and birthing areas for these highly mobile marine animals. The distribution and abundance of marine mammals and sea turtles in Hawaiian waters vary both seasonally and spatially.

Whales and Dolphins

An estimated 24 species of whales and dolphins have been sighted around the Hawaiian archipelago and may occur in the waters off Wai‘anae. Six species of endangered whales occur in the waters of Hawai‘i. These species include five types of baleen whales including the humpback (Megaptera novaeangliae), fin (Balaenoptera physalus), blue (B. musculus), sei (B. borealis), Pacific right (Eubalaena glacialis) and one species of toothed whale, the sperm whale (Physeter macrocepalus). All marine mammal species are protected under the Marine Mammal Protection Act.

Humpback Whales. Humpback whales appear in Hawaiian waters between November and April, when they socialize, mate, and give birth. When engaged in singing, nursing, or competition for mates, whales can become very vulnerable to human hazards because their attention is focused on these reproductive activities. Humpback whales are an endangered species protected under the Marine Mammal Protection Act (MMPA) and both the state and federal Endangered Species Acts. In addition, they are a valuable source of tourist revenue to the state. By law, steps must be taken to minimize potential human threats.

The Hawaiian Islands Humpback Whale National Marine Sanctuary, which includes nearshore waters along parts of all the main Hawaiian Islands, was established to protect the largest breeding grounds for the humpback whale. Humpback whales migrate annually from Alaska to Hawaiian waters, covering nearly 3,000 miles of open ocean in less than two months' time. Approximately 2,000 to 5,000 individuals come here each year, constituting a significant portion of the total North Pacific population of 6,000 to 10,000 whales.

Spinner Dolphins. Spinner dolphins (Stenella longirostris) are very common and abundant year-round in Hawaiian waters. Large groups of spinner dolphins feed and rest along the Wai‘anae coast (Dollar 1999). Spinner dolphins are a nocturnally active species with distinct residence patterns along a number of Hawai‘i's coastlines. Based on their known behavior elsewhere in the state, it is believed that these animals use selected areas along the south shore of O‘ahu during daytime hours for resting and breeding purposes. During these times, spinner dolphins become vulnerable to predation and human disturbances.

The Hawaiian name for the spinner dolphin is Nai‘a. The ancient Hawaiians recognized the special quality of dolphins and designated them as a form of Kanaloa in the Kumulipo, the Hawaiian chant of creation. Spinner dolphins are also increasingly becoming a valuable tourist attraction for Hawai‘i. Currently, the spinner dolphin is not an endangered species but is protected under the MMPA, which makes it illegal to capture, kill or hunt or harass any marine mammal. Any action that has "the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering" constitutes harassment (Sec. 3, 16 USC 1362) and is a violation of the MMPA.

Other Whales and Dolphins. Other cetaceans commonly seen in the Hawaiian Islands and which may occur along the Wai‘anae coast include the spotted dolphin (Stenella attenuatta), Pacific bottlenose dolphin (Tusriops truncates), rough-toothed dolphin (Steno bredanensis), false killer whales (Pseudorca crassidens), and the short-finned pilot whale (Globicephala macrorhynchus; Mobley and others 2000).

Sea Turtles

Five species of sea turtles inhabit waters of the Hawaiian Islands: green (Chelonia mydas), loggerhead (Carretta carreta gigas), leatherback (Dermochelys coriacea schlegeli), hawksbill (Eretmochelys imbricata), and olive ridley (Lepidochelys olivacea). Green turtles are considered the most abundant sea turtle in Hawaiian waters and may be seen off the waters of Wai‘anae. Hawksbill turtles are considered uncommon in Hawai‘i, while leatherback turtles are sighted near the Hawaiian archipelago. Olive ridley turtles are recorded mostly from entanglements and strandings.

Green Turtles. The green turtle (honu) is listed as threatened under the Federal Endangered Species Act throughout its Pacific range (except for the population that nests on the Pacific coast of Mexico, which is listed as endangered). Nesting occurs throughout the Hawaiian archipelago, but over 90 percent occurs in the Northwestern Hawaiian Islands. In the Northwestern Hawaiian Islands, green turtles migrate 1,300 kilometers (over 700 miles) from the main Hawaiian Islands to French Frigate Shoals. Green turtles can be seen foraging along the Wai‘anae coast (National Marine Fisheries Service [NMFS] and U.S. Fish and Wildlife Service [USFWS] 1998a).

Juvenile green turtles that have grown to about 30 to 35 centimeters (12 to 14 inches) live in the near-shore environments and are herbivorous, feeding on macroalgae and seagrasses. Young turtles (post-hatchling and juveniles) live in offshore pelagic habitats and are carnivorous, feeding primarily on invertebrates and fish eggs. Green turtle populations in Hawai‘i are faring better than in other parts of the Pacific, possibly due to protection of primary nesting sites in the Northwestern Hawaiian Islands and improved enforcement prohibiting harassment or harvest of the species (NMFS and USFWS 1998a).

Hawksbill Turtles. Hawksbill turtles are distributed throughout the tropics, generally occurring at latitudes from 30 degrees north to 30 degrees south within the Atlantic, Pacific, and Indian Oceans and associated bodies of water. The hawksbill turtle is listed as endangered throughout its range. In the Pacific, this species is rapidly approaching extinction due to a number of factors, but the intentional harvest of the species for meat, eggs, shell, and stuffed curio trade is of greatest impact (NMFS and USFWS 1998b).

In Hawai‘i, hawksbills nest only on main Hawaiian Island beaches, primarily along the east coast of the island of Hawai‘i. Two of these sites (Halape and Apua Point) are in the Hawai‘i Volcanoes National Park. Other beaches on Hawai‘i with recorded hawksbill nesting include Kamehame, Punaluu, Horseshoe, Ninoole, Kawa and Pohue. Not all of the presently known hawksbill beaches have nesting each year. Kamehame Point on Hawai‘i and a black sand beach at the river mouth of Halawa Valley at the east end of Moloka‘i are the most consistently used beaches. In surveys from 1989 to 1993, eighteen hawksbills were tagged and 98 nests documented. Nesting occurred from late May, with hatching completed by early December. Peak nesting activity occurs from late July to early September (NMFS and USFWS 1998b).

Leatherback Turtle. The leatherback turtle is listed as endangered throughout its range. In the Pacific, leatherback populations are in severe decline, and recovery actions have been given a high priority. Primary threats to the species are incidental take in coastal and high seas fisheries, and the killing of nesting females and collecting of eggs at the nesting beaches for food (NMFS and USFWS 1998c).

The United States does not have any nesting sites for leatherbacks in its jurisdiction in the Pacific, but has important foraging areas on the continental U.S. west coast and near the Hawaiian Islands. The leatherback is the only turtle species that remains pelagic throughout its life. It is likely that stocks in U.S. waters originate in Mexico and Central America, though some may originate from Southeast Asia as well. The lack of information on the movement patterns and habitat needs of this species severely hampers recovery efforts and must be addressed as a high priority (NMFS and USFWS 1998c).

Loggerhead Turtle. The loggerhead turtle is listed as a threatened species throughout its range. Its threatened status is consistent with population levels and trends observed in the Pacific. The stocks found in U.S. jurisdiction most likely originate from Japanese nesting areas, so activities in Japan that have an impact on nesting success or on foraging in coastal waters are of concern. The U.S. and Mexico (primarily Baja California South) provide important developmental habitats for juvenile loggerheads. A primary threat to the species in the Pacific is incidental mortalities associated with commercial fisheries, particularly long-line and net fisheries (NMFS and USFWS 1998d).

Olive Ridley Turtle. The olive ridley turtle is listed as threatened in the Pacific, except for the Mexican nesting population, which is classified as endangered. In the Pacific, the primary threats to the olive ridley appear to be incidental take in fisheries and boat collisions while in U.S. waters (or by U.S. fishing fleets; NMFS and USFWS 1998e).

References Cited

Dollar, S. 1999. Marine Environmental Investigations. U.S. Marine Corps Amphibious Training: Oahu, Molokai, and Kauai, Hawaii: Draft Report. Marine Research Consultants.

Mobley, J.R., S.S. Spitz, K.A. Forney, R. Grotefendt, and P.H. Forestell. 2000. Distribution and Abundance of Odontocete Species in Hawaiian Waters: Preliminary Results of 1993-98 Aerial Surveys. Administrative Report LJ-00-14C. Southwest Fisheries Science Center. 26 pp.

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998a. Recovery Plan for U.S. Pacific Populations of the Green Turtle (Chelonia mydas). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Green_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998b. Recovery Plan for U.S. Pacific Populations of the Hawksbill Turtle (Eretmochelys imbricata). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Hawksbill_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998c. Recovery Plan for U.S. Pacific Populations of the Leatherback Turtle (Dermochelys coriacea). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Leatherback_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998d. Recovery Plan for U.S. Pacific Populations of the Loggerhead Turtle (Caretta caretta). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Loggerhead_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998e. Recovery Plan for U.S. Pacific Populations of the Olive Ridley Turtle (Lepidochelys olivacea). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Olive_Ridley_Recovery_Plan.pdf

Related References

Au, W.W.L., and M. Green. 2000. "Acoustic Interaction of Humpback Whales and Whale-watching Boats." Marine Environmental Research 49: 469-481.

Bauer, G.B. 1986. Behavior of Humpback Whales in Hawaii and Modifications of Behavior Induced by Human Intervention. Ph.D. Thesis. University of Hawaii at Manoa.

Frankel, A.S., C.W. Clark, L.M. Herman, and C.M. Gabriele. 1995. "Spatial distribution, habitat utilization, and social interactions of humpback whales, Megaptera novaeangliae, off Hawaii, determined using acoustic and visual techniques." Canadian Journal of Zoology 73: 1134-1146.

Gardner, E. Undated. Hawaii's Marine Wildlife: Whales, Dolphins, Turtles, and Seals: A Course of Study. Earthtrust and the Hawaii State Department of Education. http://www.earthtrust.org/wlcurric/

Helweg, D.A., and L.M. Herman. 1994. "Diurnal patterns of behaviour and group membership of Humpback Whales (Megaptera novaeangliae) wintering in Hawaiian waters." Ecology 98: 298-311.

Herman, L.M., and R.C Antinoja. 1977. "Humpback whales in the Hawaiian breeding waters: Population and pod characteristics." Scientific Reports of the Whales Research Institute: Tokyo 29: 59-85.

Lammers, M.O. 2003. Behavior and Broadband Acoustic Signaling of Hawaiian Spinner Dolphins (Stennella longirostris). PhD. Dissertation. University of Hawaii.

Lammers, M.O., W.W.L. Au, and D. Feinholz. 2000. Occurrence and Distribution of Marine Mammals Along Oahu's Ewa/Honolulu Coast: A Study to Assess Potential Interactions Between High-speed Ferry Traffic and Local Populations. MMRP/HIMB Technical Report 2001. Prepared for: Pacific Marine & Supply Con., Ltd. http://oceanwidescience.org/PDF/Navatek%20Final%20Report.PDF

Mate, B.R., R. Gisiner, and J. Mobley. 1998. "Local and migratory movements of Hawaiian Humpback Whales tracked by satellite telemetry." Canadian Journal of Zoology 76: 863-868.

Mercado, E., and N. Frazer. 1999. "Environmental constraints on sound transmission by Humpback Whales." Journal of the Accoustical Society of America 106(5): 3004-3016.

Miller, J.H., T. Weber, and D.C. Potter. 1999. "Using High-frequency Active Sonar for Whale Shipstrike Avoidance." Abstracts of the 13th Biennial Conference on the Biology of Marine Mammals (Nov. 28 - Dec.3, 1999). Wilea, Maui.

Mobley, J.R., G.B. Bauer, and L.M. Herman. 1999. "Changes over a ten-year interval in the distribution and relative abundance of Humpback Whales (Megaptera novaeangliae) wintering in Hawaiian waters." Aquatic Mammals 25(2): 63-72.

Mobley, J.R., P.H. Forestell, and R. Grotefendt. 1994. Results of Aerial Surveys in Hawaiian Waters. Annual Report to the Advanced Research Projects Agency.

Mobley, J.R., S. Spitz, and R. Grotefendt. 2001. Abundance of Humpback Whales in Hawaiian Waters: Results of 1993-2000 Aerial Surveys. Prepared for the Hawaiian Islands Humpback Whale National Marine Sanctuary. http://hawaiihumpbackwhale.noaa.gov/research/HIHWNMS_Research_Mobley.pdf

National Marine Fisheries Service (NMFS). 2004. Stock Assessment Reports: Cetaceans. NOAA NMFS Office of Protected Resources. http://www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/individual_sars.html#cetaceans

National Marine Fisheries Service (NMFS). 2003. Stock Assessment Reports: Pinnipeds: Hawaiian Monk Seal (Monachus schauinslandi). NOAA NMFS Office of Protected Resources. http://www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/
Pinnipeds/Hawaiian_Monk_Seal/po03hawaiianmonkseal.pdf

Norris, K.S. 1991. Dolphin Days - the Life and Times of the Spinner Dolphin. Avon Books.

Norris, K.S., B. Wursig, R.S. Wells, M. Wursig (with S.M. Brownlee, C. Johnson, and J. Sulow). 1994. Hawaiian Spinner Dolphin. University of California Press. Berkeley, CA. 408 pp

Smultea, M.A. 1994. "Segregation by Humpback Whale (Megaptera novaeangliae). Cows with a calf in coastal habitat near the Island of Hawaii." Canadian Journal of Zoology 72: 805-811.

U.S. Fish and Wildlife Service (USFWS). 2002. Pacific Islands-Endangered Species: Hawaiian Monk Seal. http://pacificislands.fws.gov/wesa/monkhi.html

Back to top