Dilapidated Sea Wall Threatens Wildlife At Tern Island, French Frigate Shoals -- Refuge Staff Rescue Young Monk Seal

Yesterday, September 25, 2000 Acting USFWS Refuge Manager Tony Palermo and Refuge Biologist Beth Flint rescued a young monk seal, which was trapped inside the dilapidating seawall, which surrounds Tern Island.

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The 'weaner,' as newly independent seals like this one are called, had probably found its way inside the wall during a higher tide. If left
unmoved, the seal may have died from heat exposure or injured itself on the rusting, sharp edges of the wall as it struggled to get back into the ocean during low tide.

The seawall is supposed to keep Tern Island from washing away into the ocean and was built when the tiny 6-acre sandy island was expanded in 1942 in order to build an airstrip during WWII. At that time, Seabees from the Fifth Naval Construction Battalion nearly doubled the length of the island from 1,880 feet to 3,100 feet long using steel sheet pilings holding 660,000 cubic yards of coral fill dredged from the surrounding reef. Tern then became a remote military outpost used for reconnaissance and refueling. From the air, the island has been described as a large aircraft carrier made of sand, floating in the ocean.

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Over the past 60 years, the metal seawall has suffered from severe rusting and now is a major hazard for wildlife on the island, including the endangered Hawaiian monk seal. Nearly every day Palermo and his volunteers find some kind of animal trapped or dead within the wall. In fact, in addition to the monk seal, the volunteers also found a dead frigate bird (iwa) caught in the seawall. It may have died a day or two earlier.

"Monk seals, turtles, seabirds and even octopus are subject to starvation, dehydration or being impaled when they become caught between the wall and the eroding beach," explained Palermo. "Because they often can't find their way out, when the tide changes and recedes, these animals often die in the sun, unable to get back out to sea." At other areas of the island, the metal seawalls overlap, creating a trap, especially for seabirds that may inadvertently land between the walls and do not have enough room to spread their wings and fly out. Turtles also get stuck between the crevice where they can also die from exposure.

To address this problem, the US Fish and Wildlife Service, the federal agency that manages the year-round field station on the island, has obtained an $8 million appropriation to construct a new wall. Although construction isn't slated until next summer, site preparation may begin as early as next month. When construction begins, it will start at the western side of the island, near the landing dock. The work is estimated to take two years to complete. Palermo and his volunteers will do their best to monitor construction closely in order to minimize impacts to wildlife during construction.

Protecting the island from erosion is critical in order to maintain the year-round field station at Tern Island. Tern Island is the site of the longest running biological monitoring station in the Northwestern Hawaiian Islands. Data have been collected at Tern for 23 years on seabirds, monk seals and turtles. These data is valuable to scientists when assessing changes over time in tropical ecosystems.

"There is so much variability in wildlife throughout the year, how they behave, their numbers and where they go from month to month," said Beth Flint. "In order to fully understand the biology and ecology of both migratory and resident tropical animals, year-round data collection is crucial. For example, some seabirds live as long as 50 years. To try and understand them and their behavior fully, it is important not only to have year round data, but to also have data that spans over decades for comparison. This kind of data can only be acquired through a long-term monitoring station which is what makes Tern Island such a valuable place."

Tern Island is part of the Hawaiian Islands National Wildlife Refuge and was established originally as a bird refuge in 1909 to protect seabirds from feather poachers. It became a monitoring field station in 1979 when the Coast Guard closed its LORAN station on the island. Since then the seabird populations on the islands have been steadily climbing, making the island a breeding ground for hundreds of thousands of seabirds including albatross, terns, shearwaters and boobies.


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