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Lionfish Cruise Logs › Day 2
Day 2: July 18, 2005
Today on the RV Nancy Foster we traveled farther offshore and conducted
our deepest dives yet.
Air Temperature: 90 °F
Surface Water Temperature: 86 °F
Bottom Water Temperature 74 °F
Sites are located approximately 60 miles south of Beaufort Inlet in 146 feet
of water. We were able to survey for lionfish and native grouper at three
sites and collected live lionfish as well as returning dead specimens for analyses.
The weather continues to be outstanding and the underwater visibility is about
60 to 70 ft. The sites we visited today are very low relief unexplored natural
hard bottom reef habitats. We found lionfish at all nine sites explored in
the past two days. In addition, we deployed a temperature sensor that will
allow us to better understand how bottom water temperatures may be controlling
the geographic distribution of lionfish.
The divers collect lionfish by netting them underwater. Lionfish are
placed in insulated tanks to bring back to the laboratory for later study
Courtesy of Thomas Nassif.
The sites we surveyed today were extremely low relief with few rocky
outcrops. Lionfish are found primarily on submerged structure such
as coral reefs or hard bottom. In this image, a lionfish is nestled on
the sandy sea floor between tufts of algae. We have found lionfish on
every kind of structure, and they were found in high numbers even at
these mixed sand and algal locations.
Courtesy of Doug Kesling NURC.
Pictured here is an example of a temperature probe with a mooring
fabricated by Jay Styron of NOAA's Undersea Research Center in Wilmington.
Because it is very difficult to find small objects in deep water, Jay
designed a 6 ft mooring for our sensor that consists of a large white
float attached to a 6 ft polypropylene line, anchored by a heavy weight.
The temperature sensor is the small black object located halfway up on
the mooring. With luck we can retrieve the sensor in a year and find
out what the year round bottom water temperatures are at our locations.
This will shed light on where lionfish can survive off North Carolina.
Courtesy of Doug Kesling.
In order to quantify the number of lionfish and other native species
along the seafloor, divers use a method known as the line (band) transect
method to estimate the area covered. In this picture Roldan Munoz is
reeling in a meter tape he used in his transect surveys. Without a method
to estimate area covered, it is difficult to determine fish population
densities.
Courtesy of Doug Kesling.
