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French Frigate Shoals
9/28/07

by Yumi Yasutake

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This past September, I was fortunate enough to be selected as the designated outreach person on the Northwestern Hawaiian Islands Coral Reef Assessment and Monitoring Program (NOWRAMP). The purpose of the trip was to visit three islands in Papahānaumokuākea Marine National Monument, returning to particular sites around each, and collecting data on the abundance of fish, coral, limu, and invertebrates.  Surveys from each year is compiled and compared to previous years’, helping scientist to better understand the ecosystem dynamics of these isolated habitats.

 
Scientist surveying the relative abundance and species of corals present around the island. Credit: Yumi Yasutake

After a two and a half day transit from Pearl Harbor aboard the NOAA research vessel Hi`ialakai, I awoke Thursday morning to the sight of La Perouse Pinnacle in the far distance off the starboard bow. 

La Perouse Pinnacle. Credit: Yumi Yasutake

Off the port deck near the horizon, there appeared to be three or four floating warehouses, which are actually the remnant structures of an old U.S. Coast Guard station.  Built on nothing more than a large sand island, the station is so low lying that it looks as if there is no land under it at all.  After breakfast, three of the rigid hull inflatable dive boats were systematically loaded with gear and divers, then sent off on their full day of surveys.  I was in the last of the three and also the largest boat of them all.  Named the HI-1, it is a 10 meter, 370 horsepower diesel driven jet boat.  Meaning, it is not moved with a propeller like most conventional boats, but with a forceful stream of water much like a jet-ski. 

Our first survey point was approximately 5 miles away from Hi`ialakai, within the barrier reef of the lagoon which was made up of mostly very fine white sand, and small patches of reef randomly placed about.  Aside from the fact that I was approximately 450 miles northwest of the Main Hawaiian Islands, French Frigate Shoals seemed to have a strangely familiar feel.  Growing up on the island of Kaua`i, I have been a lifelong fisherman, diver, and overall lover of the ocean.  Traveling to various coastal as well as landlocked states within the continental U.S. as a youth, I learned a deep appreciation for my island home at an early age.  The shapes of the clouds, the types of seabirds soaring above, the temperature of the water, the waves breaking on the barrier reef, even the smell of the salt breeze were all sensations I’ve experienced, and come to love while fishing around Hawai`i. 

As soon as I jumped into the 15 feet of lagoon water I was immediately inspected by a 40-50 pound white ulua.  His curiosity brought him within a couple of feet as he circled me like a hungry shark looking for an easy meal.  As I began to explore the other inhabitants of the area, many common sights filled the viewfinder of my underwater camera.  Small colorful reef fish, a couple of small `omilu, and even a tiger cowry was to be found on a hefty clump of coral rubble.  I felt as if I had ascended into a dream world as the silhouettes of three meaty uku came into sight.  I couldn’t believe it!  Any seasoned fisherman in Hawai`i can tell you that deep ledges with moderate current are the uku’s usual habitat.  That’s why I would never have thought to find them in that shallow and clam of water.

The lack of fishing pressure around French Frigate shoals make ulua and uku a common sight on just about every dive. Credit: Yumi Yasutake

Survey site #2 was also in the lagoon, just inside of the barrier reef on the Northwest side of the atoll.  By now I was accustomed to the large ulua, array of reef fish, and even a small white-tip reef shark that decided to see what all the commotion was about.  But it wasn’t until dive site #3 that a major revelation consumed me.  This site was also on the Northwest side of the atoll, but this time on the outside of the barrier reef in about 40 feet of water.  There was some minor trade wind chop creating white caps on the gentle swells, and the visibility wasn’t all that great.  Although we were in the mid-day sun, the water was dark and there was a lot of suspended particulate matter.  The bottom, classified by the researchers as spur and groove, was mainly hard ridges of reef with parallel trenches of sand.  Aside from the colonies of small table corals, it reminded me very much of the reef outside the Hilo break wall.  The small reef fish were not that abundant, nor were there any rare species present.  Just a few small uhu, manini, hinalea, and the ever-present humuhumu.  Though I was expecting to see large apex predators on every dive just because I was in the Northwestern Hawaiian Islands, it didn’t seem that the reef in this location was capable of supporting species of the upper trophic levels.  After 5-10 minutes in the water I let go of the hope for seeing something big and just focused on taking pictures of the unique table corals. 

Table corals like these are common around French Frigate Shoals and elsewhere in the tropical pacific, but very hard to find around the Main Hawaiian Islands. Credit: Yumi Yasutake

At that moment, the calm mood that the reef fish were displaying went into panic mode as a beautiful 50-60 pound ulua lazily swam within view.  He circled the divers a few times, then slipped back into the blue haze from which he appeared, only to make way for a healthy gray reef shark.  As I surfaced for another breath of air and dropped back down in hopes of a picture, the shark vanished without a trace of it ever being in the area.

So many times we blame the lack of large apex predators in the Main Hawaiian Islands on supposedly poor reef structure, but French Frigate Shoals proved that theory wrong.  Indeed, healthy coral colonies and suitable shelter for fish make for an abundant and diverse reef habitat, but it seems that human impacts severely out weigh those factors in determining the relative abundance of desirable food species.  Even on the seemingly desolate reefs around French Frigate Shoals, large uku and ulua are still present, giving us a glimpse of what the reefs probably looked like in old Hawaii before an era of natural resource exploitation and unsustainable fishing practices.

One of the many sand islands that are critical resting sites for monk seals, turtles and seabirds. Credit: Yumi Yasutake

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