related materials
- Cruise Report (PDF)
About NOAA Oscar Dyson
OSCAR DYSON is designed for a wide range of fisheries research, with capabilities for midwater and bottom trawling, hydroacoustic surveys, and oceanographic and hydrographic operations.
OSCAR DYSON can trawl in water up to 1,000 fathoms deep. In addition to her large trawling nets, smaller sampling nets and towed fishing gear can be deployed over the stern, over the side of the working deck, or from the starboard side-sampling station. Longlining and other types of fishing are also possible. Find out more about OSCAR DYSON
Ichthyoplankton 2009
May 7-20, 2009
We examined the interactions among climate, weather, and the recruitment of fishes in the eastern Bering Sea
Ichthyoplankton -- the eggs and larvae of fish -- are found throughout the water column, from very shallow waters (<50m) to abyssal depths.
Studies of ichthyoplankton ecology help us determine how and when larvae are recruited to juvenile nursery grounds in the Bering Sea.
Chief Scientist Janet Duffy-Anderson and the research team focused on arrowtooth flounder, Pacific cod, and walleye pollock, looking at where these species and their plankton prey were distributed throughout the water column.
The sampling
The team collected ichthyo- and zooplankton at 81 stations using bongo nets and a neuston net. See a larger map of sampling stations.
Net contents were then sorted live or preserved in a chemical solution for later analysis.
Left: Deploying bongo nets to collect samples. (Tracey Smart)
What they found
The team found abundant walleye pollock eggs but relatively fewer pollock larvae. Very cold (< -1ºC) water temperatures may have influenced the location or timing of spawning adults. The team caught only 25 larvae at 15 stations around the Pribilof Islands, and no Pacific cod.
Right: Scientists Debbie Blood and Tracey Smart sort through the contents of a bongo net for fish larvae. The brown color of the water is due to the high abundance of diatoms. (Chrissy Jump)
However, within Unimak Pass and over Bering Canyon, the team found the cruise's highest larval diversity -- approximately 12 genera. Previous years of sampling in Unimak Pass have demonstrated that larvae routinely drift from spawning areas in the Gulf of Alaska through Unimak Pass to the Bering Sea.
Sea ice in May
Traveling back toward the Alaska Peninsula to continue the search for pollock and cod larvae, the ship navigated through a large field of sea ice (right). (Tracey Smart)
Sea ice in this area is unusual for mid-May, and has not been documented for at least 10 years. Sea ice is further evidence of the very cold conditions over the middle and outer shelves.
Further plankton sampling along the Alaska Peninsula revealed that larvae of any fish species were relatively scarce at most stations and water temperatures remained low until the team cruised further west.
Drifter release
Researchers also released 3 satellite-tracked drifters on this cruise (see the map to find out where drifters were released). A summer 2009 cruise led by Dr. Nicola Hillgruber will use the drifter data to conduct additional sampling for the Bering Sea Project.
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.
NORTH PACIFIC RESEARCH BOARD 
NATIONAL SCIENCE FOUNDATION
Contact the BEST-BSIERP Program Manager with project-related questions.
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