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frigate shoals
French
Frigate Shoals
French Frigate
Shoals is an open atoll consisting of a large, crescent-shaped reef
surrounding numerous small, sandy islets. While the land area is only ¼
square kilometer (67 acres), the total coral reef area of the shoals
is over 938 square kilometers (232,000 acres).
 French
Frigate Shoals exhibits the classic features of a well-developed coral
atoll. The coral growth is atop an eroded volcano, which has been submerged
for millions of years. A steep-sided basalt pinnacle juts out of the
water in the center of the atoll. This unique rock formation is the
last remnant of the original volcano. The pinnacle was named "La
Pérouse Pinnacle" after Compte de La Pérouse, who
visited the atoll in 1786. In the moonlight the pinnacle so resembled
a full-rigged sailing ship that it lured more than one vessel to her
doom on the shoals as Captains investigated the unidentified companion.
Tern Island,
a part of the atoll, was formed into a runway to serve as a refueling
stop for planes enroute to Midway during World War II. The original
seawall, runway, and some of the buildings remain.  The
U.S. Fish and Wildlife Service continues to maintain a field station
there, which is staffed year-round by two permanent employees and a
handful of volunteers.
The reef
system associated with French Frigate Shoals supports the greatest
variety of coral species in the NWHI with forty one species of stony
corals documented. These include table, finger, and lobe corals. Table
corals of the genus Acropora, which are common throughout
reefs of the central and south Pacific, are essentially absent in the
Main Hawaiian Islands (MHI) but
are common at FFS. The chevron butterflyfish (Chaetodon trifascialis),
which feeds exclusively on polyps of Acropora corals, is likewise
absent in the MHI but common at FFS. It also supports more than 600
species
of invertebrates such as sponges,
coral worms, snails, lobsters, crabs, shrimps and clams, oysters, sea
urchins, and sea stars. Many of which are endemic species.
 More than
150 species of algae live among the reefs, including red, green and
brown algae. Especially diverse and lush algal communities are found
immediately adjacent to La Perouse Pinnacle, leading phycologists (algae
scientists) to speculate that influx of additional nutrients in the
form of guano are responsible for the high algal productivity in this
habitat.The
outer reef waters support gray reef sharks, butterfly fish, and large
schools of jacks and groupers. Endemic masked angelfish
(Genicanthus personatus) are occasionally seen here at scuba
diving depths. In the Main Hawaiian Islands, they are rarely seen shallower
than 300 feet.
 Hundreds
of green sea turtles inhabit French Frigate Shoals. Over 90% of the
threatened Hawaiian population of green sea turtles travel to the shoals
for safe nesting. Satellite tagging of these turtles indicates that
most of them migrate to the Main Hawaiian Islands to feed and reach
sexual maturity before returning to French Frigate Shoals to breed.
Some of these turtles travel northwest to feed, while others travel
as far south as Johnston Atoll.
The many
small islets of French Frigate Shoals provide refuge to the largest
sub-population of endangered Hawaiian monk seals. Preserving this atoll
is critical to their survival.
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