29 April 2001
Report of Activities on the R/V N.B. Palmer

We are now at -66 33.576°S; -69 20.137°W (18:45 local) and steaming on west-northwest course (305) towards Station #8 at about 11 kts. The wind has slacked off over the previous highs in the 30 kt range during mush the last couple of days and is now about 20 kts. The air temperature is just about 0°C.

The last couple of days has seen the start of the broad-survey, a grid of 84 stations distributed across the Western Peninsula Shelf from just North of Adelaide Island to a bit south of Marguerite Bay.

Work commenced at Consecutive Station #1 (grid locaion 499.251) with a couple of CTD casts, a shallow one with the Fast Repetition Rate Fluorometer and a deep cast without the FRRF. BIOMAPER-II was deployed into the water shortly after the last CTD cast and was towyo'd in a sawtooth pattern between the surface and 200 to 250 m as the ship steamed at about 5 kts towards the next station. For this first deployment, wind was from about 260 degrees at about 20 to 25 kts and there was a large swell under white capped seas. Skies were mostly overcast, but occasionally the sun almost broke through.

BIOMAPER was taken out of the water around 1130 at Station # 2 after doing two good towyos because of electrical problems. We continued to steam to Station #3 and the CTD work was continued along with the bird and marine mammal observations. The afternoon was spent cleaning, re-greasing, and reseating nearly all the connectors on the towed body. By late afternoon, BIOMAPER-II was back together and the deck testing through the electro-optical cable showed everything was working and there were no faults. But the work was completed about the time we arrived at Station 3, so we decided to wait until after the CTD and MOCNESS tow to deploy BIOMAPER-II again.

The CTD was completed about 0700, but there was considerable work to be done to get the MOCNESS out onto the stern deck and ready for a tow. The seas were very rough and fairly frequently the stern would dip under the sea surface and water would flood the deck. There is a lip around the deck, supposedly to help in the case of an oil spill, but the result is that the water stays on the deck sloshing back and forth. This is also reinforced by the fact that the ship is beamy and the deck has no camfer. Rubber boots under a mustang suit are mandatory to work on the stern deck in the kind of seas we have been having. With light snow swirling around our heads and while the MOCNESS frame was lying on the deck, Carin Ashjian, Mark Dennett, Jan Zelag, Maureen Taylor, Scott Gallager, and I put on the deflector flaps, attached the car batteries for the strobe light system to outboard sides of the top frame, and put on the net response. Then the nets were loaded and then the net bar traps were installed just above the bottom I-beam. The strobe light was tested on the deck and it worked fine.

The deployment of MOCNESS was hampered some because the seas were large and the ship was pitching a lot, but we got the net in reasonably well. During the lowering of the net system, electrical problems developed, but were corrected before the start of the oblique section of the tow where nets are sequentially opened and closed. The tow went down to 300 meters (the water depth was about 360 m). The strobe light was turned on just before the net #1 was opened and ran flashing at 4-second intervals for the remainder of the tow. The depths sampled were 50 m intervals from 300 to 100 m and 25 m intervals from 100 to the surface. Although the net response did not work on most of the net closings, it was clear at the end of the tow that all of the nets had opened and closed properly.

The catch was interesting. There were some fairly large euphausiids (krill) in the deepest samples, but they were not abundant. The mid-portion of the tow had a sparse catch and the upper 100 m had fairly good catches of juvenile and adolescent krill beginning about 75 meters. Larval krill (furcilia) were very abundant starting about 50 m and they were especially high numbers in the upper 25 meters. Copepods also seemed particularly abundant between 50 and 25 meters. By about 2330, we were done with the MOCNESS.

We then moved immediately to get the BIOMAPER-II back into the water. Just at midnight we made the launch with the ship pitching, the wind blowing 30 kts and a light snow swirling around us. The seas were really running at least 15 feet and to launch off the stern required some timing to make sure one of the big rollers was not about to lift the stern up and then drop it precipitously down into the trough. We turned all of the sensor systems on once the fish was below 15 meters and very shortly after that one critical (internal 12 volt) and one warning forward fault light (Environmental Sensing System - ESS) appeared. But we went with it and started the towyo. Cabell Davis, Mark Dennett, and Karen Fisher came into the van shortly after
everything was turned on to start their midnight to four watch and they took over the control of the towyo to the next station.

Cheers, Peter