Life of a Spinner Dolphin
Naia in Hawaiian
As the sun sinks below the horizon and Earth enters into the golden corpuscular hour, groups of spinner dolphins make their way offshore into deep, dark blue water up to 1,000ft. They are on the hunt for prey. Working together in large groups they use clicks, squeaks, and echolocation to communicate with each other to find food. Dolphins feed on fish, squid, and shrimp. They will corral fish into tight packs and then send a few dolphins at a time flying through the pack to catch a meal. Upon the return of sunlight, the spinner dolphins break back up into smaller groups and swim closer to the islands and into shallower waters.
The spinner dolphin is one of three species of dolphins we commonly see in Maui waters with the others being bottlenose and spotted dolphins. The spinner is a small dolphin species found in tropical and sub-tropical waters around the world. True to its name, spinner dolphins jump out of the water and rotate before splashing back down into the water. They can spin up to 5.5 times in one jump. While we are not positive why spinners perform these acrobatics, marine biologists think it may be a form of communication. Individuals on the outer edges of the group will jump and splash around to tell the rest of the group what direction and speed to travel in (wilddolphin.org). Spinner dolphins may also tail slap, a behavior where they display their tail out of the water and slap the surface creating a splash. This behavior is thought to be a danger signal telling the group to change direction or dive.
The spinner dolphin is a nocturnal species. Dolphins never sleep, instead, they rest because they are conscious breathers. Unlike us, they need to keep part of their brain active and actually think about breathing in order to take a breath. While resting they go into an alpha state. This is when an animal rests half of its brain at a time and keeps the other half active in order to breathe and be aware of any predators. Predators of spinner dolphins include sharks, false killer whales, and short-finned pilot whales. They are also in danger of being entangled by marine debris.
Spinner dolphins breathe through a hole located on the top of their head, called a blowhole. At the surface of the water they expel air at speeds of up to 100 mph. An individual can empty and refill their lungs in a fifth of a second or less. Passengers can get an up close view of this process if the dolphins choose to bow ride with the boat. Dolphins are curious and playful creatures and will often play in the waves alongside a boat's bow.
There are five distinct populations of spinner dolphins in the Hawaiian Islands.
Pearl and Hermes Reef
Kauai and Niihau
Oahu, Maui, Lanai, Molokai, Kahoolawe,
Hawaii Island (NOAA Fisheries).
Hawaiian spinner dolphins live in family groups and return to relatively the same area during the day to rest. On our Discover Lana'i tour, we occasionally see a group of spinner dolphins in the Au'au Channel between Maui and Lana'i. Trilogy operates under the Dolphin SMART guidelines which is a volunteer program Trilogy has agreed to participate in to promote dolphin conservation. It is important for humans to keep our distance from wild animals because interactions may make the animal loose fear of humans or boats. Any activity that disrupts an animal’s natural behavior is termed harassment and is illegal under the Marine Mammal Protection Act. Trilogy also limits our viewing time with the dolphins to 10 minutes.
All dolphins are protected under the Marine Mammal Protection Act and the Endangered Species Act. Currently NOAA (National Oceanic Atmospheric Administration) Fisheries is working on more regulations in order to protect dolphins from human impacts and harassment. The proposed rule would prohibit swimming with and approaching a Hawaiian spinner dolphin within 50 yards (NOAA Fisheries, http://www.fpir.noaa.gov/PRD/prd_spinner.html)