Patch Dynamics at Sea 2009
The at-sea component of the Bering Sea Project Patch Dynamics component, run by Kelly Benoit-Bird and Scott Heppell, is charged with mapping the “buffet table” available to place-based foragers such as seabirds and fur seals on the Pribilof Islands and along the Aleutian chain.
The team listens to the ocean, samples it with nets, and measures a variety of oceanographic parameters to characterize the habitat and the composition, abundance, and energetic content of food available to kittiwakes, murres, and fur seals in the southern Bering Sea. These data will then be used in conjunction with foraging behavior and reproductive success measures of the birds and fur seals to determine how prey type and availability affects the population dynamics of these top-level predators.
Right: The team leaves Dutch Harbor to begin a month's worth of at-sea sampling. (Kelly Benoit-Bird)
Expanded sampling for 2009
The 2008 sampling season had used a single chartered fishing vessel and focused on a 100km radius of St. Paul Island in the Pribilofs. For 2009, the team chartered two commercial fishing vessels -- the F/V Frosti and the F/V Goldrush -- out of Dutch Harbor to accommodate the expanded scope of the project, which included sampling both around the Pribilofs and near Bogoslof Island, located in the Aleutians just west of Unalaska/Dutch Harbor.
Right: Sampling area and transects. See larger image
The sampling “universe” extended approximately 100 km east and west of Dutch Harbor along the northern side of the Aleutians, and north to approximately 100 km north of St. Paul. At each sampling station the team conducted a vertical plankton tow, recorded conductivity-temperature-depth (CTD) information (link), and pulled a trawl. They then procee ded along the 10km transect, collecting more hydroacoustic information, and conducted a second CTD cast at the transect’s end.
Lost gear required them to modify their sampling plan from the original design, but over the course of 26 days they conducted more than 140 individual trawls and collected thousands of kilometers of continuous acoustic data.
Right: The F/V Goldrush made a port visit to St. Paul, and met up with the on-island bird and mammal crews. (Scott Heppell) See larger image
First looks at the 2009 data
Initial catch data indicate that in 2009 there are much larger amounts of age-1 pollock than in 2008, and that most of these were located northwest of the Pribilof Islands. We saw fewer but larger age-0 pollock in 2009, both around the Pribilofs and near slope waters. In the slope waters there were some very large catches of euphausiids, and -- unlike in 2008 -- deep sea smelt, not lanternfishes, dominated nighttime samples.
Left: Greg Kowalke, Neal McIntosh, and Stephanie Archer admire a catch of 21,000 age-1 pollock caught by the F/V Goldrush northwest of St. Paul (Scott Heppell)
The team will continue to analyze these data over the next several months, and look forward to providing data to the ecosystem-level modeling efforts that will work towards predictions of change in the Bering Sea.
The BEST-BSIERP Bering Sea Project is a six-year study of the Bering Sea ecosystem,
from the benthos and the atmosphere to human communities, and everything in between.
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