2005 Prehurricane Survey of Raccoon Island, Louisiana

By: Tommy Michot (Pilot/Biologist)

Chris Wells (Observer/Geographer)

Flight Date: August 27, 2005

Aircraft: N727 (DOI 08) Cessna 185 Amphibian

Route of Flight: Lafayette, Bay Junop, Raccoon Island, Bay Junop, Old
Oyster Bayou,

> Lafayette

Storm Name: Hurricane Katrina

Storm Date (projected landfall): August 29, 2005

Max sustained winds (projected): Category 5

Background

Raccoon Island is Louisiana's most important seabird nesting site west
of Breton Sound. Numerous seabird species including the brown pelican
(*Pelecanus occidentalis*), black skimmer (*Rynchops niger*), sandwich
tern (*Sterna sandvicensis*), laughing gull (*Larus atricilla*) nest on
the island and forage in the important fishery areas west of the island.

The low tide extent of the island has declined since the 1950s from
nearly 283 ha (700 acres) to 97 ha (240 acres) mapped in 2003. The most
dramatic losses have been noted in the wake of major storms such as
Hurricanes Audrey (1957), Betsy (1965), Carmen (1974), and Andrew
(1992). To protect this important barrier island rookery from further
loss, State and Federal partners built an experimental system of
breakwaters in hopes of lessening the erosion of the island. Hurricane
Lili's impact on the island in 2002 appeared to have proved the concept
that the breakwaters help. It is more than likely that Hurricane Katrina
will provide an additional, if unwelcome test of the breakwater
protection.

Researchers at the USGS National Wetlands Research Center along with
other Federal and State agencies have been monitoring Raccoon Island for
decades resulting in a series of vegetation habitat maps dating back to
the 1950s and breeding bird colony data since the 1980s. Most of the
nesting by the seabirds takes place on the vegetated, eastern portion of
the island, about half of which is protected by the breakwaters. This
information has been used to guide management of this important resource
for the benefit of the species and for Nation.

Methods

Observations were recorded and oblique digital photographs were taken
from the aircraft of the island at two altitudes, 350 m (1,148 ft) and
180 m (591 ft). The island was circled at both altitudes with
overlapping photographs acquired along both shorelines over the length
of the island. In addition, several photographs of the eastern end of
the island were taken at a near vertical angle to provide more details
for photointerpretation and mapping.

Photographs

31-35 Oyster Bayou. This is a long-term marsh study site for USGS
research scientists.

36-37 Raccoon Island, 350-m altitude. Western end of island viewed from
the north.

38-40 Raccoon Island, 350-m altitude. Middle portion of island.
Vegetated but not protected by breakwaters.

41-44 Raccoon Island, 350-m altitude. Eastern portion of island.
Vegetated and protected by breakwaters.

45-48 Raccoon Island, 350-m altitude. View of entire island from the
east. Easternmost breakwaters are clearly visible.

49-51 Raccoon Island, 350-m altitude. Easternmost end of island viewed
from south. Breakwaters and mangroves are clearly visible. Also note the
well developed tombolos (sand accretion) attaching the breakwaters. Some
vegetative colonization is occurring on the tombolos.

52-62 Raccoon Island, 350-m altitude. Near-vertical photographs of the
eastern end of the island behind the breakwaters. Vegetation patterns
are evident.

63-69 Raccoon Island, 350-m altitude. Central and western end of the
island from the south.

70-71 Raccoon Island, descending to 180-m altitude. View of entire
island from the west.

72-76 Raccoon Island, 180-m altitude. Western end of island. Mostly
unvegetated clearly showing sand splays from occasional overwashes from
the south.

77-84 Raccoon Island, 180-m altitude. Central portion of island
unprotected by breakwaters. Vigorous vegetative growth\--mostly
mangroves, but also some *Spartina patens* and *Spartina alternifolia*
grasses\--covers much of the island.

85-90 Raccoon Island, 180-m altitude. Eastern portion of island
protected by breakwaters. Some patches of mangroves are dead and
defoliated on the interior lagoons, likely because of high
concentrations of guano.

91 Raccoon Island, 180-m altitude. View of entire island from
low-oblique.

92-115 Raccoon Island, 180-m altitude. Low-oblique photos of southern
shore. Flying birds, especially brown pelicans, can be seen in most of
this series.

116-126 Close-up photographs of nesting pelicans. Note the dead
mangroves.

127-144 Bay Junop USGS research site.

145-148 Old Oyster Bayou USGS research site.