GU0505 - Fall SEAMAP Groundfish Survey - Leg I, II & III

October 8 - November 15, 2005

*GU0505 - Fall SEAMAP Groundfish Survey - Leg I, II & III*
*October 8 - November 15, 2005*

On this cruise, the Gordon Gunter participated in the SouthEast Area Monitoring and Assessment Program (SEAMAP), shrimp and bottom fish survey, in the northern and western U.S. Gulf of Mexico. The primary goal of the survey was to study the abundance and distribution of bottom populations occurring in the area between Brownsville, TX and Mobile, AL. This stretch of waters is one of the busiest, most commercial in the US, where vessels of all kinds, large and small, share the waters with thousands of oil and natural gas rigs and platforms. It is also the primary US fishing grounds for shrimp. Data for this survey has been collected annually since 1971. Therefore, it was most important that the Gordon Gunter, after one of the severest hurricanes in US history, Katrina, got underway as soon as possible to maintain the continuity.

On October 8th, the Gordon Gunter departed Pascagoula, headed towards Brownsville, TX, to begin the survey. As with years past, 238 stations were randomly selected by a computer, designed to cover the different depth strata from 5 to 60 fathoms (9.2 to 109.2 meter). In addition, 1/2 of the stations were designed to be sampled during the day while the other half, during the night (determined by sunrise and sunset). The sampling gear consisted of 40-ft shrimp nets with 8-ft by 40-inch chain bracketed wooden doors. Minimum and maximum tow durations were 10 and 55 minutes respectively, depending on the time required to transect the respective depth strata. If a stratum was not completed in 55 minutes then additional tows were made until it was covered. The photos of the chart below visually display the concept of covering different depths as well as day and night trawls. (Click on photos to enlarge)

Chart displaying our working grounds on Leg II of the Survey - between Galveston, TX and west of the Mississippi River Delta (see inset on the right for details)	Red Dots - Day Trawls, Blue Dots - Night Trawls, Yellow Dots - Historical Hangs Green Dots - Plankton Stations (CTD, Bongo & Neuston). Black dots represent oil rigs.

The photos below describe the sampling and data collecting processes: (Click on photos to enlarge)

Hauling in the net	Hosing off the mud	The 'catch'	The 'catch' - close look
The catch is shoveled into baskets	Waiting for the conveyor belt	Conveyor belt	Sending the fish to the wet lab
The Lab end of the conveyer belt	Sorting the fish	Sorting the fish	Fish on the measuring table

In addition to the trawl operations, the ship took water and ichthyoplankton samples at pre-determined locations (green dots):
Samples (conducted with CTD rosette, bongo and neuston nets) were collected at half-degree intervals of latitude and longitude within the defined survey area. The CTD rosette (Conductivity, Temperature, Depth) was lowered to the bottom to record the Depth, water column Conductivity (to derive the Salinity), Temperature, Dissolved Oxygen, Chlorophyll, Percent Light Transmission and Fluorometer. Water samples were taken at the bottom, mid-depth and surface. Bongo tows were made with two conical 61-centimeter nets with 0.333 mm mesh netting. Nets were towed at approx 1.6 knots to maintain a 45 degree wire angle of towing warp, and were fished to a maximum depth of 200 meters or within two meters of bottom in depths less than 200 meters. Neuston sampling gear consisted of a 0.947 mm mesh net mounted on a 1 by 2 meter frame. The net was towed at a speed of 2.7-3 kts for 10 minutes with the frame half submerged at the surface. Bongo and neuston samples were initially preserved in 10% buffered formalin and then transferred to 95% ethyl alcohol 48 hours later.

Lowering the CTD
Bongo net
Neuston net
Neuston net in tow

On the 2nd and 3rd legs, a group of scientists from Northwest Fisheries Science Center in Seattle were checking for organic pollutants in fish and water, caused by hurricane Katrina. According to scientist Mark Peterson, flooded sewage systems could cause the release of bacteria that are potentially harmful to human health into sea water. According to scientist Paul Olson, exposure to chemical contaminants would reveal itself in the muscle tissues of shrimp & fish as well as bile and liver of fish. "In fact", says Mr. Olson, "analysis of the fish and shrimp's bile can diagnose the source of petroleum or type of oil causing the pollution". It is a complex and costly analysis, performed at the shore based lab. To learn more about it, please visit www.nwfsc.noaa.gov

Testing fish tissue for
harmful bacteria
Removing ear bones from fish to
determine age
Extracting bile
Shrimp 'puree'

Testing for harmful bacteria - close up
Scientist Paul Olson at work
Collecting fish liver

In addition to the main operations described above, we participated in a world wide program to monitor oceans' currents by sending off a 'drifter buoy' near the mouth of Galveston Bay, TX. Also, while trawling for fish, we occasionally caught a sea turtle. The scientists measure the turtle from end to end, took samples & photos then tagged and released the animal.

FPC Debose sending off the boxed drifter buoy
Drifter buoy - the instrument
Sea turtle, brought
onboard as by-catch,
waiting to be measured
Measuring, sampling
& tagging before
releasing back to sea
Keeping sea turtle wet
while measuring and
tagging
LF Barbosa, SF Ropiak
& scientist Bates moments before releasing

In addition to the trawl operations, the ship took water and ichthyoplankton samples at pre-determined locations (green dots): Samples (conducted with CTD rosette, bongo and neuston nets) were collected at half-degree intervals of latitude and longitude within the defined survey area. The CTD rosette (Conductivity, Temperature, Depth) was lowered to the bottom to record the Depth, water column Conductivity (to derive the Salinity), Temperature, Dissolved Oxygen, Chlorophyll, Percent Light Transmission and Fluorometer. Water samples were taken at the bottom, mid-depth and surface. Bongo tows were made with two conical 61-centimeter nets with 0.333 mm mesh netting. Nets were towed at approx 1.6 knots to maintain a 45 degree wire angle of towing warp, and were fished to a maximum depth of 200 meters or within two meters of bottom in depths less than 200 meters. Neuston sampling gear consisted of a 0.947 mm mesh net mounted on a 1 by 2 meter frame. The net was towed at a speed of 2.7-3 kts for 10 minutes with the frame half submerged at the surface. Bongo and neuston samples were initially preserved in 10% buffered formalin and then transferred to 95% ethyl alcohol 48 hours later.
Lowering the CTD	Bongo net	Neuston net	Neuston net in tow

On the 2nd and 3rd legs, a group of scientists from Northwest Fisheries Science Center in Seattle were checking for organic pollutants in fish and water, caused by hurricane Katrina. According to scientist Mark Peterson, flooded sewage systems could cause the release of bacteria that are potentially harmful to human health into sea water. According to scientist Paul Olson, exposure to chemical contaminants would reveal itself in the muscle tissues of shrimp & fish as well as bile and liver of fish. "In fact", says Mr. Olson, "analysis of the fish and shrimp's bile can diagnose the source of petroleum or type of oil causing the pollution". It is a complex and costly analysis, performed at the shore based lab. To learn more about it, please visit www.nwfsc.noaa.gov
Testing fish tissue for harmful bacteria	Removing ear bones from fish to determine age	Extracting bile	Shrimp 'puree'

In addition to the main operations described above, we participated in a world wide program to monitor oceans' currents by sending off a 'drifter buoy' near the mouth of Galveston Bay, TX. Also, while trawling for fish, we occasionally caught a sea turtle. The scientists measure the turtle from end to end, took samples & photos then tagged and released the animal.
FPC Debose sending off the boxed drifter buoy	Drifter buoy - the instrument	Sea turtle, brought onboard as by-catch, waiting to be measured	Measuring, sampling & tagging before releasing back to sea	Keeping sea turtle wet while measuring and tagging	LF Barbosa, SF Ropiak & scientist Bates moments before releasing

Last but not least, in between doing science, several spirited individuals took Halloween seriously, dressed up for the occasion and entertained us all -

The Gordon Gunter's mess deck, decorated for Halloween	Scientist Lanora	ENS Taylor	ENS Perry	Seasick pumpkin	Having fun...	CDR Meigs 'spooked' by Scientist Olson

Photo credits on this webpage go primarily to scientist Paul Olson as well as CDR Meigs, Field Party Chief Andre Debose and 2M Miri skoriak. All photos property of NOAA.

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•  Updated:September 20, 2006