Getting to Know Bottlenose Dolphins
Jumping high into the air in impossible acrobatic feats, and behaving curious and spirited underwater, bottlenose dolphins are a rare treat to observe on a dive charter. Living 40 to 60 years, these very social and playful mammals form friendships that last decades hunting, mating and protecting each other. Bottlenose dolphins may travel alone or in groups of about 12, however, larger herds of hundreds are also seen together. They grow to be 6 to 12 feet long and can weigh up to 1,300 pounds. Fun fact: Every two hours, they shed their outermost layer of skin.
To and from dive sites, we more commonly see spinner dolphins surf in the waves and wakes of Lahaina Divers boats, but it is not unheard of to see bottlenose too. We see bottlenose in some of the farther reaches, so you might spot one near Molokini. If you are lucky while diving, you might observe them and swimming through self-made bubble rings. They may also take off in a flash- bottlenose can swim up to 22 miles an hour!
Bottlenose dolphins reach sexual maturity between 5 and 14 years old, and reproduce nearly their entire lives. After a 12-month gestation period, a calf is born. Females give birth every three to six years. These marine mammals use distinct sounds and body language to send messages to other members of the herd, including snapping their jaws, squeaks, squawks and slapping their tails on the water.
The characteristic whistle of dolphins is unique to each individual animal, much like a human’s name. Dolphins create this sound shortly after birth. Bottlenose also use high-frequency clicks which are used as a sonar, called echolocation. When the sound hits an object or animal, it tells the dolphins the distance, shape, size and location of the object. They also have a sharp sense of hearing. Sounds travel through the lower jaw to its inner ear which is then transmitted to the dolphin’s brain, according to scientists.
These highly intelligent animals use sound to communicate and to hunt for food. They consume about 13 to 15 pounds of their primary diet of fish, squid, and shrimp. They will hunt in groups, creating a mud ring to trap fish. Then, some of the dolphins wait outside the ring, gobbling up any fish that attempt to escape.
The Hawaiian name for all dolphins is nai’a (the spotted dolphin is called kiko nai’a). Other species commonly found here are rough-toothed dolphins, and the spinners mentioned earlier. Pilot whales and false killer whales are also part of the Hawaiian dolphin family. Dolphins can dive deep and travel up to 80 miles in a day, but are commonly seen in shallow-water areas around the main Hawaiian Islands, especially Maui, Lanai and Molokai.
Although bottlenose dolphins are not considered endangered or threatened in the United States under the Endangered Species Act (ESA), they are protected by the Marine Mammal Protection Act (MMPA). They are susceptible to many stressors and threats, such as disease, biotoxins, pollution, alterations to their habitat, boat strikes, human feeding, harassment, oil spills and underwater noise caused by humans. So while they seem to enjoy respectful human interaction, they do need our help and protection. While diving, please do remember dolphins are wild animals, no matter how friendly they appear, and should be observed with caution.
NOAA Fisheries helps conserve bottlenose dolphins through collaborative management, integrated science, partnerships, and outreach. It is against the law to feed or harass wild dolphins. NOAA asks, “For the dolphins’ sake, and for your safety, please don’t feed, swim with, or harass wild dolphins.”
Scientists use a variety of innovative techniques to study, protect, and rescue bottlenose dolphins in distress. If you see a marine animal in distress, please contact the Hawaiʻi Statewide Marine Animal Stranding, Entanglement, and Reporting Hotline: (888) 256-9840. This hotline includes stranded/injured sea turtles, monk seals, dolphins, and whales.
Maui County also bans the captive display of any marine mammals, which includes dolphins, porpoises and whales. The reason is cetaceans are highly intelligent and social animals. The dysfunctional social structure of captive cetaceans is known to cause severe harm to the animals. As the Humane Society of the United States puts it, “Dolphins belong in the ocean.”
We are honored to share the marine environment with bottlenose dolphins and all ocean creatures, and share our conservation knowledge with our dive buddies.