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Polar Ecosystems Program:  Ice Seal Breeding Ecology Cruise
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Polar Sea Cruise

Field Reports from the Oscar Dyson

Post Date: 22 April 2008
Bering Sea
Latitude: 54.386
Longitude: -165.327
Posted By: Josh London

Welcome to the Bering Sea

back deck of the Dyson
Making way to the Bering Sea, Three Zodiacs are visible on the back deck.

At approximately 08:00 AM this morning, the NOAA Ship Oscar Dyson transited through Unimak Pass and entered the Bering sea. We now estimate arrival at the ice edge sometime Wednesday afternoon.

  science party in survival suits
Science party in survival suits.

Post Date: 20 April 2008
Kodiak, AK
Latitude: 57.78
Longitude: -152.42
Posted By: Josh London

And, We're Off. Farewell Kodiak

After 14 days, the science party and crew of the Oscar Dyson bid farewell to Kodiak. The Oscar Dyson pulled away from the dock at approximately 10:00 AM local time. Some final calibrations and tests needed to be run by the visiting engineers. Those tests went quicker than expected and, by around 3:00 PM, we were off for Unimak Pass. We expect to reach Unimak Pass sometime early on Tuesday (22 April) morning and hope to be near the ice by Wednesday afternoon.

The extended delay has certainly been a challenge for all those involved. I am proud to say the science party and crew of the Oscar Dyson remained in good spirits and kept a positive attitude. Those good vibes will be crucial as we try to accomplish some of our objectives in a shorter period. We assembled our Zodiac boats and secured them on the back deck soon after departure. Soon after departure, we also went through various safety briefs and drills with the ship’s crew. We will spend much of the transit preparing any remaining gear so we are ready to launch boats as soon as we encounter seals.

The main challenge we now face is finding seals. We have various streams of information to help us decide where to start looking. We are receiving daily satellite images from the National Ice Center. Most of these images use a scatterometer to interpret sea-ice from sea surface roughness. Sea-ice is typically rough compared to the surrounding open water. The main advantage this imagery provides us is the ability to look through clouds so we get information regardless of the weather. We are also receiving visual imagery from MODIS and AVHRR satellites. The seals we deployed transmitters on during last year’s cruise are also providing us with information on where seals are. The transmitters come on every 4 days and we get updates of locations sent directly to a laptop on the ship. Lastly, our colleagues on the USCG Polar Sea will be flying aerial surveys in our area and can provide additional feedback on ice conditions and seal distribution.

  dead Steller sea lion
Dead male Steller sea lion found on Near Island, Kodiak.

Post Date: 17 April 2008
Kodiak, AK
Latitude: 57.78
Longitude: -152.42
Posted By: Heather Ziel

Steller Sea Lion Necropsy

On April 16, Kathy Hough (Senior Survey Tech on the Oscar Dyson) spotted a dead Steller sea lion floating around in the harbor, not too far from the Dyson. The next day she organized a necropsy and asked if we could assist. Five scientists from our party participated in the necropsy and it was a good feeling to get out and collect some scientific data while our ship is still being repaired. Even though we do not work on Steller sea lions as part of our program, other colleagues at the National Marine Mammal Laboratory were eager for us to get samples and collect what we could. We were primarily interested in seeing whether there was any obvious signs of death (e.g., trauma from an orca attack or boat strike), and we wanted to collect any tissues that could be analyzed for disease and other health parameters. Vicki Vanek, a veterinarian who works with the Alaska Department of Fish and Game in Kodiak, came along to direct the necropsy.

We went out with a skiff provided by the Alaska state troopers. We found the sea lion across the harbor, resting on some rocks just off Near Island. When we got to the animal, we could see it was extremely bloated, and Vicki could tell it had been dead for several days. We towed the sea lion off the rocks and over to a small, rocky beach on Near Island. Once there, our first challenge was to roll the animal over so that Vicki could see all sides and look for bite marks or other obvious trauma. The animal was a fully grown adult male sea lion. It took both Gavin and Shawn pulling from shore and a couple of us using boat hooks from the boat to turn the animal over enough so that Vicki could see all sides. The sea lion had some old teeth marks on its body, but no fresh trauma was found.

After taking several external measurements, the real work of the necropsy began. Vicki delicately cut open the animal and began taking what samples she could and looking for any clues of what killed the animal. She was extremely considerate of everyone and warned us when she was about to cut into the body cavity. I was grateful she did because it gave me time to cover my nose a little, and even with! That was an amazing smell! Those in our party who had not previously participated in a marine mammal necropsies gained an appreciation for those in the marine mammal stranding network who do this on a regular basis.

Tissues samples are only good for histology when the animal is freshly dead. Unfortunately, this animal had been dead too long so we did not collect as many samples as we had hoped. We did collect some large blubber samples, skin for genetics, a few whiskers, and muscle samples. The lower jaw was also collected and the teeth will be used for determining age of the animal. These samples are relatively rare and will provide other researchers with additional data on Steller sea lions around Kodiak and the western Gulf of Alaska.


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