Eric Velarde: Beginning Seafloor Dredge Tows, June 17, 2013


NOAA Teacher at Sea
Eric Velarde
Aboard R/V Hugh R. Sharp
Wednesday, June 13, 2013 – Monday, June 24, 2013

Mission: Sea Scallop Survey
Geographical Area: Cape May – Cape Hatteras
Date: June 17, 2013

Weather Data from Bridge
Latitude: 40.07°N
Longitude: 73.05°W
Atmospheric Pressure: 1025 mb
Wind Speed: 4.6 knots
Humidity: 85%
Air Temperature: 18.33°C
Surface Seawater Temperature: 18.46°C

Science & Technology Log

Suspending flight of the HabCam V4 & beginning the first of the seafloor dredge tows was the focus of work on June 17, 2013. In order for seafloor dredge tows to occur, the HabCam V4 is withdrawn from the sea to eliminate risk of accidental collision or entanglement.  After the science team raises the HabCam V4 to a safe depth, the engineering team assumes responsibility of HabCam V4 retrieval through winch operation on the loading deck. When not in operation, the HabCam V4 rests on the loading deck for cleaning & maintenance until seafloor dredge towing is complete. While being a delicate scientific recording instrument, the HabCam V4 also possesses the engineered fortitude to withstand the demands of oceanic scientific research.

HabCam V4 Withdrawal

HabCam V4 Withdrawal

Dredges aboard scientific vessels are 8’ wide, New Bedford style commercial scallop dredge frames, fitted with a ring bag and sweep on the bottom.  The ring bag is built from 2” interconnected metal facets.  Additionally, a 1.5” polypropylene liner is installed inside the ring to capture all sizes of Sea Scallops. In contrast, commercial vessels have two 15’ wide dredges with 4” rings so that younger, smaller scallops pass through the net. Once the dredge is lowered to the seafloor, it is dragged behind the vessel for 15 minutes at a speed of 3.8 knots before being lifted onto the vessel for sorting, categorization, and measurement. The engineering team assumes responsibility of lowering & raising the dredge while the science team dons foul weather gear for the messy, but detailed analysis of the catch.

Engineering Team Raising Dredge Tow

Engineering Team Raising Dredge Tow

Once the dredge tow catch is aboard, collaboration between the science and engineering teams occurs so that the catch can be quickly, but accurately sorted into species. All dredge tows are focused on analyzing Atlantic Sea Scallop populations at predetermined points on the ships trajectory. In addition, fish, and sometimes sea stars and crabs require subsampling to assess their population as well. Sea Scallops must be weighed and measured en masse before being returned to their seafloor habitat. In addition, subsamples of Scallops are dissected so that the sex, gonad weight, and meat weight can be recorded.

Measuring Scallops with FSCS

Measuring Scallops with FSCS

All scientific analysis of captured specimens occurs in the scientific lab, which houses FSCS (NOAA Fisheries Scientific Computer system) which is a combination of touch-screen computer monitors, electronic measuring boards, and digital weight scales. The scientific lab is portable, loaded with scientific sampling equipment in Lewes, DE by the scientific team before being carefully loaded onto the vessel prior to departure. Working & cleaning in the scientific lab is nearly effortless due to its engineered design, allowing for streamlined operation.

Scientific Laboratory

Scientific Laboratory

Personal Log

One of my favorite aspects of the seafloor dredge tows is the dissection of the scallops. I enjoy dissection because it is slower than the rest of the operations that occur after the catch has been sorted, giving me time to observe and record the internal anatomy of the scallops. I also enjoy dissection as it grants me time to work in systematic symmetry with the luminous La’Shaun Willis, a Bennett College ’98 Alumnus. Her warming energy is radiant, making me feel as if I am back in Greensboro, teaching & learning alongside my students at The Early/Middle College at Bennett. Listening to her speak about her life journey causes me daydream about the scientific possibilities that await my students when I return to Greensboro, North Carolina with this newfound experience to fuel their continued character, leadership, and academic development. I am constantly filled with inspiration as she shares priceless nuggets of wisdom with me.

Scallop Subsampling

Scallop Subsampling

Following each seafloor dredge tow, the science and engineering teams work to shuck the largest of the scallops for closer analysis of meat weights when the science team returns to the lab in Woods Hole, Massachusetts. Admittedly, I am not very adept at shucking, but I am learning quickly from some of the most talented shuckers I have come into contact with. They transform shucking into a scientific art of speed, precision, and accuracy.

Shucking Scallops

Shucking Scallops

One of the benefits of working from Midnight-Noon is that I get to soak in the warmth of the rising sun, which, as expected, is breathtaking. Each new day has been filled with awesome scientific beauty, wonder, and energy. Several days of seafloor dredge tows will succeed today, eventually followed by the return of the HabCam V4 to the sea as the vessel makes its returning voyage to port.

Sea Sunrise

Sea Sunrise

Did You Know?

Atlantic Sea Scallops inhabit the seafloor from Cape Hatteras at their southernmost range, to Newfoundland at their northernmost range.

-Mr. V

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