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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

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Post Date: 26 April 2008
Bering Sea
Latitude: 60°
Longitude: -178°
Posted By: John Jansen

Our First Capture Attempts

Oscar Dyson behind juvenile ribbon seal
The NOAA ship Oscar Dyson passes behind a juvenile ribbon seal.

To now, the wind and ocean currents have created concentrations of dense ice pack with an impenetrable edge. We have scanned hundreds of kilometers of ice edge finding no shortage of seals hauled out deep in the ice inaccessible to our small inflatable capture boats. And no surprise we have grown increasingly eager to launch the boats should any seals venture within a hundred meters or so of open water. That finally happened at the far northwestern edge of our search area, close to the International Date Line.

The quality of the ice in this area was different: larger floes with some relief and, more importantly, dispersed enough to allow boats to move through them. This is just what we did once we spotted three ribbon seals from the bridge. As quickly as we could don our dry suits, radios, and GPSs, the crew of the NOAA ship Dyson had craned our boats into the water and were ready to load. Despite getting very close to the first two seals, they were just a hair quicker than us. The third seal was a long shot to start, smartly being tucked away in the pack and watching us "sneak" through the ice before bailing into the water.

It was then that the crew spotted six killer whales following a lead near the ship. The photographs of the pod will be analyzed by others at NMML to determine if they are known animals (via unique markings). We wondered whether they were fish or mammal-eaters and whether the ribbon seals we were stalking were also aware of potential predators in the area. After a few more hours of searching for seals from the small boats, the fog rolled in and we snaked our way through the ice maze back to the ship.

Many conditions have to be just right to catch a seal, so despite not deploying any satellite tags today we were encouraged by being able to find catchable seals in a relatively short time. Last year, it took about the same time to find an area where seals and workable ice overlapped. We are hopeful these conditions will persist for our last couple days in the ice before returning to Dutch Harbor.

  juvenile ribbon seal
Juvenile ribbon seal on an ice floe.

Post Date: 24 April 2008
Bering Sea
Latitude: 59.330
Longitude: -175.567
Posted By: Josh London

Finally, Ice and Seals

We spotted our first sections of sea-ice yesterday afternoon. While we were excited to see the ice, we spent most of the afternoon and evening making final preparations to our boats and capture gear. We have such a short time in the ice (maybe only 5 days), we want all our gear ready to go at a moment's notice. This year we are trying some new equipment to help us stay warm and dry while working amongst the sea-ice. The temperature outside is just below freezing and the water temperature is -2 degrees Celsius. We will be wearing dry suits with fleece liners that provide us relatively good mobility for running and catching seals, while also providing a necessary level of safety should one of us end up in the water. On top of the dry suits we wear and inflatable PFD and white jackets and pants to reduce our visibility to the seals.

But, before we can get out amongst the ice and seals, we need to find them. Today was our first full day of observations from the bridge of the Oscar Dyson. We have observers on watch from 9am to 9pm. This corresponds to approximately the middle of the solar day. We are so far to the west, the Alaska time zone does not provide an accurate representation of the sun's position in the sky. In this region, the sun is at its peak 2-4 hours after noon. We know from tags we deployed on seals last year that they are more likely to be out of the water, on the ice, in the mid to later portion of the solar day.

Our observations on the bridge involve 2-3 people scanning with binoculars and spotting scopes for any seals in view. When we spot a seal, the first thing we do is evaluate whether we feel the seal could be captured. If not, then as the ship passes the seal and sighting is recorded into our computer. In addition to recording the species and sex (when possible), we also record distance to the seal and characteristics of the ice and floes in the area. The data from our bridge observations will add to our knowledge of ribbon and spotted seal distribution in the Bering Sea. It also provides us the best opportunity to spot seals that might be worth a capture attempt. Hopefully, we'll have some of those opportunities soon.


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