Sharks, Turtles, and Seals

While the bulk of the work I and the local Fish and Wildlife staff are involved with here at Midway Atoll pertains to restoring degraded lands to better support wildlife, the place that these small islands hold within the larger seascape is something that everyone here thinks about daily.  In fact, Midway Atoll National Wildlife refuge is just a small part of the vast Papahānaumokuākea Marine National Monument which encompasses 139,797 square miles.  (If you want to know how the name “Papahānaumokuākea”, was chosen, what it means, and how to pronounce it, click here.)

The problem with large numbers is that they can be hard to comprehend, but 139,797 square miles is a really big area, so big you could fit all the US national parks within it. Stretching from the island of Nihoa just west of Kaua’I to Kure Atoll (a distance equal to that of New York City to Omaha), the monument is mostly deep ocean but it encompasses 11 islands and atolls and hundreds of miles of coral reef.

Sharks, Turtles, and Seals are constant reminders of the fact that Midway Atoll is surrounded by a big, wild ocean and testimony to the conservation importance of this place. Of these, I will admit to only seeing the latter two so far, but since I like to swim and snorkel, sharks are on my mind a lot and even though I will admit to having some fear about encountering a shark, I also look forward to seeing some while I’m here. Like many top predators, sharks are declining worldwide. Highly sought after as food, trophies, and other uses, and also vulnerable to marine pollution and industrial fishing practices, nearly half of shark species are at risk of extinction though recently sharks have received more protection in both the United States and abroad. At Midway four shark species are seen regularly: Galapagos Shark, Blacktip Reef Shark, Whitetip Reef Shark, and Tiger Shark.  Of these the Tiger Shark has the worst reputation and I am told that if I see one while swimming, I should exit the water quickly. Some sharks, including Whitetip Reef Sharks, distinguish themselves from other fishes by seemingly resting on the bottom of the ocean for long periods of time. Although I'm keen to see sharks here at Midway I'd be perfectly content if I got to see them while standing on the pier!

Sharks are frequent visitors to the deep water harbor on Sand Island. Swimming is not allowed there!

Like the albatrosses, petrels, and terns, sea turtles and seals lead a dual life, spending time both in the ocean and on land. Although six species of sea turtle occur in the Pacific, only two regularly occur in the Northwestern Hawaiian Islands: Green Turtles and Hawksbill Turtles. Hawaiian green sea turtles, a genetically distinct race of the much more widespread Green Sea Turtle are a common sight at Midway Atoll. For decades they have frequented a certain beach – aptly called Turtle Beach – on Sand Island which is just a five minute bike ride from my house. I don’t actually ever go to turtle beach to check them out as they are sensitive to disturbance and thus it’s not permitted. But because they spend a bit of time foraging on algae at the nearby Cargo Pier where I go snorkeling, I see them pretty regularly.  Green Sea Turtles throughout the world have had a hard road for some time. Hunted for their meat, their eggs taken from their nests to be consumed as delicacies, and entangled in both fishing nets and marine debris populations are in pretty bad shape. Because of this many green sea turtle populations, including those found throughout the Hawaian Islands, are listed as Threatened by the US Endangered Species Act. The protection seems to be working as populations haveincreased by about 50% in the past 25 years.  Hawaiian green turtles are large (up to 400 lbs), very long lived (at least 60-70 years), and nest exclusively at a place called French Frigate Shoals, more than 500 miles from Midway!  Watching turtles swim is something I really appreciate about living here at Midway.  They show an amazing combination of grace, power, and determination in their movements.

Upper left: Turtles frequently bask on “Turtle Beach” on Sand Island. Basking allows turtles to conserve energy and regulate their body temperature. Lower right: Turtles often are seen swimming and diving from the Cargo Pier just to the west of Turtle Beach. 

The HawaiianMonk Seal is one of just three monk seal species worldwide, all of which occur in tropical climates. All monk seal species have been exploited extensively by human hunters and are either endangered (Hawaiian and Mediterranean monk seals) or extinct (Caribbean Monk Seal).  Hawaiian monk seals live only in the Hawaiian Islands and despite the protection afforded them by the Endangered Species Act and the Marine Mammal Protection act, still number only around 1000 individuals today of which the vast majority live in the Papahānaumokuākea Marine Monument. These seals face myriad threats which range from entanglement in marine debris to harassment by people (seals have even been found dead with gunshot wounds on the Main Islands!).  The latter isn’t a big deal here in the Northwestern Islands because there are only 50 or so people and they areas frequented by seals are strictly off limits. Out here though, competitionfor food with fish and predation by sharks are major factors limiting thepopulations. 

 Upper left: Visitors to Kaena Point (look for blue umbrella in the rocks) on the island of Oahu ignore the Do Not Disturb signs meant to protect Hawaiian Monk Seals; Lower right: A mother and pup rest, undisturbed on a beach on Eastern Island, Midway Atoll.

Living with seals is a real privilege though we must always be careful as to not to accidentally disturb them. Earlier this week while walking on the beach, my friend Ann Humphrey and I accidentally came upon a mother with a young pup hauled out on the sand and had to quickly turnaround and take a very long and inconvenient route behind the dunes to avoid them. Seals are a top priority here on Midway and, in fact, two entire sides of the island (including the former “Officer’s Beach”) are off limits because of their popularity with the Hawaiian Monk Seal!

Learning about the lives of far ranging, ocean inhabitants like sharks, turtles, and seals makes me wonder about all the amazing places within across the vast area that makes up the Papahānaumokuākea Marine Monument. If, like me, you are interested in seeing these places you can take a "virtual visit" at NOAA's website.