![News text image](images_old/subhead_news2.jpg)
Wayne
Hoggard
Fishery Biologist
NMFS, Pascagoula Laboratory
2002 Mid Atlantic Bottlenose Dolphin Aerial
Surveys![Picture of dolphins in the Atlantic](images/projects_2.jpg)
Along
the eastern seaboard of the United States there exists
a coastal migratory stock or population of bottlenose
dolphins (Tursiops truncatus). This nomadic stock of
dolphins moves north and south along the coastline depending
on the season and water temperature. During the summer
months the dolphins are dispersed between New Jersey
and south Florida. As water temperatures begin to drop
in late fall, the dolphins
move south and their northern range extends only to
the waters off Cape Hatteras, North Carolina. During
1987-88 a major bottlenose dolphin die off occurred
along the mid Atlantic and some estimates suggest that
this coastal migratory stock was reduced to only 50%
of its original size. Because of the die off, the stock
was declared “depleted” and therefore elevated
to a status that required a more aggressive conservation
plan.
Aerial
surveys are one tool used by NOAA's National Marine
Fisheries Service to assess and monitor populations
of marine mammals . The NOAA Twin Otter aircraft was
chosen because it provides a safe and versatile platform
that is ideally configured to conduct marine life surveys.
The aircraft has twin turbine engines, the latest in
navigational and safety avionics, and plexi glass bubbles
that provide observers an unobstructed view of the water
and trackline. The aircraft's payload allows for the
use of two independent survey teams; therefore, separate
estimates can be compared, allowing a more precise population
estimate. The Twin Otter is equipped with camera ports
in the nose and belly of the aircraft enabling the use
of high resolution digital photography and videography.
A infrared thermometer is mounted in the belly that
records sea surface temperatures during the entire survey.
A normal survey crew consists of a NOAA pilot and co
pilot, 5 trained marine mammal observers and 2 data
recorders. For each bottlenose dolphin sighting, the
aircraft is diverted and the herd is circled until the
species identification can be confirmed and a herd estimate
obtained. This information is then entered into an onboard
computer, interfaced with the aircraft’s global
positioning system (GPS). Information is also recorded
on sea turtles, fish schools, shipping traffic and marine
pollution. These data are then used to calculate abundance
or population estimates for bottlenose dolphins and
any other marine life of interest.
During 2002 aerial surveys were conducted between Sandy
Hook, New Jersey, and Vero Beach, Florida, to update
the previous 1995 estimates. A winter (Jan. Feb.) and
summer (July Aug.) period were surveyed in order to
compare the distribution and population estimates between
the two periods. Final results have not been published,
but preliminary estimates demonstrate that the two team
approach helped improve the precision and accuracy of
estimates as compared to 1995. This year NOAA’s
Twin Otter flew 250 hours in support of the Mid-Atlantic
Bottlenose Dolphin Survey. Mid-Atlantic surveys are
again planned for 2004 and the NOAA Twin Otter will
be the aircraft of choice. |