The Ultimate Guide to Hawaiian Spinner Dolphins

While there is no doubting that whale watching season in Maui is one of our favorite times of the year,  the only bad part about whale season in Maui is that it eventually comes to an end. Our spinner dolphins, on the other hand, are playful residents of Maui waters who stay with us throughout the year, and as a Dolphin SMART operator we welcome the opportunity to help educate and protect our native dolphins. Since Hawaiian spinner dolphins are such a highlight of our sailing tours in Maui, we figured we'd compile this online guide to help you understand more about them. These are some of the most frequently asked questions we receive about our Hawaiian spinner dolphins, and if you still have any questions at the end of the article you can leave them in the comments below. 

So, how big are Hawaiian Spinner dolphins? They look pretty small?

Photo Credit: Island Dream Productions

When compared to larger species such as bottlenose dolphins (which can grow up to over 12 feet in length), Hawaiian spinner dolphins appear pretty small. A fully- grown Hawaiian spinner dolphin is only 5-6 feet long, and when the babies are born and swimming alongside their mothers they measure a mere 2.5 feet! (Ironically, the world's smallest dolphin is the "Maui" dolphin which is only found in New Zealand, and these endangered dolphins only grow to a maximum length of 5 feet). One way the Captain can classify a spinner dolphin from afar is by looking at the size of the dorsal fin, which will always be a smaller than a bottlenose or pan-tropical spotted dolphin.

Why the name Hawaiian Spinner dolphins, and why do they spin?

As the name suggests—the dolphins are able perform up to seven rotations while jumping completely out of the water. There are different species of spinner dolphins located in various corners of the globe, but the Hawaiian spinner dolphins are a distinct subspecies which inhabit Hawaiian waters. As for the reason why the spinners spin, there are numerous theories which are considered by researchers, but nobody knows for sure. The leading theories are that they are trying to remove parasites or pesky remora fish which cling on to their fins, or that they are using the spinning as a form of communication to get the attention of others in the pod. There has also been a theory put forth that the spinning is a sort of "exclamation point" which serves as a final thought on whatever they just did, but for the most part, the reason why spinner dolphins jump out of the water is simply because they can.

Check out a video of spinner dolphins jumping off of the island of Lanai

What is the best place to see Hawaiian Spinner Dolphins?

In Maui County, there are three distinct populations of spinner dolphins which you're likely to encounter. On our snorkeling tours to Lanai, we often encounter a pod of Hawaiian spinner dolphins who frequent the southwestern coastline. We'll often see these dolphins on the way to Shark Fin Cove (Kaunolu), outside of Hulopo'e Bay, or along the cliffs which stretch from Manele Harbor to Kamaiki Point. In South Maui, there is a pod of Hawaiian spinner dolphins which frequent the area around La Perouse Bay, and occasionally we will spot these dolphins on our snorkeling tours to Molokini. Finally, on the west side of the island, there is a pod of dolphins along the West Maui coastline which you can sometimes find around Honolua Bay or directly off Ka'anapali Beach.

Photo Credit: Island Dream Productions

What do Hawaiian Spinner Dolphins eat?

Hawaiian spinner dolphins hunt in groups like an aquatic pack of wolves. Targeting species such as lantern fish and squid (both of which are around two inches in size), spinner dolphins can attain depths of over 1,000 feet in search of food for the pod. All feeding takes place at night, which is when the dolphins move to deeper water offshore from the main Hawaiian Islands. Other predators such as large sharks are a major concern to the dolphins, so they hunt together in a large group to increase the safety in numbers. And even though they have moderately sharp teeth, theories have been put forth that a large pod of spinner dolphins can actually kill or immobilize prey simply by directing targeted sound waves at the prey. Whoa.

Photo Credit: Island Dream Productions

How do spinner dolphins sleep?

Knowledge about the sleep cycles of Hawaiian spinner dolphins is one of the most important aspects of keeping them protected. Unlike us humans who "turn off" our brains whenever we go to sleep, spinner dolphins remain in an "alpha state" where a portion of their brain is always switched on so that they remember to come up to breathe. In essence, each hemisphere of their brain takes a short "cat nap" while the other half stays awake, and during this rest period there isn't any spinning or energetic surface activity. Because they spend all night hunting, Hawaiian spinner dolphins like to rest during the day in shallow waters by the shoreline

Can I swim with Hawaiian Spinner Dolphins?

This is one of our most frequently asked questions, and the short answer is that, no, you can't, because swimming with spinner dolphins during the daylight hours is very disruptive of their sleep cycle. Because they have stayed up all night hunting, the dolphins need to rest during the daylight hours to prepare for another round of hunting (remember, just because the dolphins are still swimming doesn't mean they are awake). When you swim into a pod of sleeping dolphins, it is no different than jumping into someone's bed while they are trying to take a nap; the disturbance ends up waking the dolphins, and consequently they get a poor sleep due to the constant interruptions. While this might not seem like that big of a deal, research has shown that the alertness level of Hawaiian spinner dolphins has seen a decrease in recent years, and there has been a marked increase in Hawaiian spinner dolphins with wounds from cookie cutter sharks (after all, it's harder to evade a predator when you've been up all night).

On the other hand, if you just happen to be swimming in a place like Hulopo'e Bay and a pod of dolphins surrounds you, the best thing to do is not to chase after them and sit back and enjoy the show.

Can you hear Hawaiian Spinner Dolphins underwater?

Yes, and it's amazing! When Hawaiian spinner dolphins are in the general vicinity of where you're snorkeling in Maui, there is a distinct series of clicks and whistles which seems to hover overhead. The sound even more noticeable when snuba diving in Maui (since you're underwater, of course). Because sound can travel very well in water, but is almost impossible to tell which direction it's coming from, the sound of dolphins can seem both distant and close and and create an enchanting soundtrack to your snorkel.

Click here to hear recordings of spinner dolphins in Hawaii. 

Do spinner dolphins migrate to Alaska like the whales?

Hawaiian spinner dolphins are year-round residents of the waters here in Hawaii. The reason that whales migrate north to Alaska is because their food source isn't found in Hawaii. The spinner dolphins, on the other hand, feed on small fish which are found in Hawaii so there isn't the need to leave. In fact, preliminary research has shown that there are three distinct populations of spinner dolphins even within the Hawaiian Islands: a population which remains around the island of Kauai, a population which inhabits the central chain (from Oahu-Maui County), and a population which lives in the waters of the western coastline of the Big Island. So not only do the dolphins not migrate to Alaska, but they barely migrate within the state of Hawaii!

Photo Credit: Divemaster Matthew Wheeler

How many dolphins are in a pod?

The questions of how many dolphins are in a pod is actually a complicated issue. Sometimes you can encounter pods containing upwards of 300 dolphins, whereas other times you can find pods of spinner dolphins which barely stretch over 15. While the exact answer to this question is disputed, one thing that researchers seem to agree on is that the average pod size is shrinking. One theory which has been suggested for the decreasing pod size is that since human interaction with dolphins has increased (ie swimming with dolphins during their resting hours), adult pod members don't have the same level of alertness which is required to protect the pod from attack. There has been a marked increase in the number of scars from cookie cutter sharks, and it's theorized that younger members of the pod could be more vulnerable to predation when the pod hasn't been adequately rested. The good news is that we can regularly encounter a pod off of Lana'i with dolphins which number in the hundreds, and while this makes for exhilarating dolphin viewing on our snorkeling tours to Lanai, it's important we pay attention to sustainable practices to ensure their long-term survival.

Photo Credit: Divemaster Matthew Wheeler

What are the predators of Hawaiian Spinner Dolphins?

In addition to cookie cutter sharks and larger sharks which only frequent the open ocean, spinner dolphins also must watch out for false killer whales. 

Why do dolphins swim on the bow of the boat?

While we always give dolphins a respectful amount of space so as not to disturb their sleep patterns, there are some times when dolphins will approach our catamaran and swim along the bows. The reason for this is that the boat creates a compression wave just beneath the surface of the water, and the dolphins can literally "surf" in the wake of the wave which is just off the bow.

 

Have you ever had a dolphin spin on to the boat?

No, we have never had a dolphin spin on to the boat—although you would never believe the height some of these dolphins can get when they leap just mere feet in front of you!

Have any other questions about Hawaiian spinner dolphins? Leave them in the comments section below and we'll do our best to provide an answer. All media in this article adheres to Dolphin SMART guidelines, and for more information on our Maui snorkeling tours where you can encounter Hawaiian spinner dolphins, visit www.sailtrilogy.com. Or, follow Trilogy on Facebook for photos of dolphin sightings whenever they occur on our boats. Aloha! 

Photo Credits: [Mikol on Flickr (how big are spinner dolphins); Brad Scott (migrate), Rocky Silverman (false killer), Jason Clark (pod left), Mark Driessen (pod right), Kristen Belew (can I swim with Hawaiian spinner dolphins) ]

 

 

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