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Polar Sea Cruise

Field Reports from the Oscar Dyson

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Post Date: 29 April 2008
Bering Sea
Latitude: 59.44604
Longitude: -174.73196
Posted by Josh London

Successful Capture on the Last Day

crew weighing seal
The PEP field team weighs a subadult ribbon seal. Photo by Dave Withrow.

Today was the last day we would be able to work in the sea ice before having to head for Dutch Harbor. We selected a spot further to the southeast from where we have been the last few days. The area looked promising based on the satellite imagery and it was closer to Dutch Harbor so we would have the whole day to work.

We arrived at the general area of interest this morning and started exploring the ice for seals. Despite seeing what we believed to be 'good ice' for seals, we had not seen any seals by lunch. At around 3pm the ship reached the end of a leed and couldn't go any further. So, we decided to launch the boats for one last effort. Because our zodiacs are smaller and more maneuverable, we were able to search further into the ice. Within 30 minutes of launching the boats, our radios were buzzing with excitement

"Zodiac 3. Zodiac 3. Zodiac 2. There's a seal to your right"

"Roger Zodiac 2. I have the seal in sight"

All three boats quickly got into position, and we were able to execute a textbook approach that resulted in a successful capture by Shawn Dahle. The animal was a ribbon seal, 73kg and sub-adult male. We know the animal was a sub-adult because the hair was light brown and had not developed the striking ribbon characteristic of adult males.

field team with ice seal
satelittle transmitter attached to flipper
The team measures a captured ribbon seal and attaches a small satellite transmitter to the rear flipper. Photos by Dave Withrow.

Our team quickly went to work weighing, measuring and drawing blood for health analysis. The last step in the process is to attach a satellite transmitter to the rear flipper of the animal. These transmitters are small and designed to minimize impact on the animal's behavior. Because the tags only transmit when the tag is above water, we only receive locations when an animal is hauled out on ice. However, because these tags are attached to the flipper, they will likely stay on for 1-2 years. We hope this information will provide a better understanding of the relationship ribbon seals have with the sea ice during pupping and breeding.

Approximately 40 minutes after capture, the animal was released and we quickly packed up our gear, hoping to find another seal. Unfortunately, after an additional 3 hours of searching, we did not find another seal in the area. We returned to the Dyson and started the journey back to Dutch Harbor.

Although the mechanical difficulties and long delay in Kodiak were frustrating, we were able to put those thoughts behind us with a successful capture. Hopefully, the animal we caught today will continue to provide valuable data for the next few years.

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