These surveys serve as one of several research platforms from which summertime Bering Sea Project research is conducted.
Distribution and abundance data on pollock and their prey (euphausiids, a k a 'krill'), water temperature, salinity, nutrients, oxygen, and chlorophyll are pieces of the puzzle that Bering Sea Project scientists are trying to solve so that they can better understand how pollock distribution has changed in recent years -- and how it may change in the future.
Get more detail on the seven projects that make up the fishes portion of the Bering Sea Project, including project summaries, statements of work, and project leads. Go to Fishes Focal Area
Educators from NOAA's Teacher at Sea (TAS) program assisted Bering Sea Project scientists with the acoustic pollock survey in the Bering Sea and blogged about life aboard the ship. Go to their blogs, below:
TAS provides a unique environment for learning and teaching by sending K- through college-level teachers to sea aboard NOAA ships to work under the tutelage of scientists and crew. Then, armed with new understanding and experience, teachers bring this knowledge back to their classrooms. Learn more about NOAA Teachers at Sea.
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
Walleye pollock support the largest single commercial fishery in the U.S., producing the largest catch of any one species inhabiting the 200-mile U.S. Exclusive Economic Zone. The largest concentrations of pollock occur in the eastern Bering Sea.
As the most abundant midwater fish in the Bering Sea, pollock are also ecologically important both as a predator upon smaller fish and zooplankton, and as prey for larger fish, whales, and seabirds. Learn more about NOAA's pollock research activities.
NOAA scientists have annually assessed the status of pollock annually since 1977 so that managers can keep the fishery sustainable.
They combine data from midwater trawl surveys with acoustic (echo integration) technology to create a picture of pollock distribution and abundance.
Right: an acoustic plot showing fish at different depths above the sea floor. (image courtesy NOAA-AFSC)
Research is also conducted on fishing gear performance and on fish behavior during the capture process to develop methods that reduce bycatch in commercial fishing operations.
A 2008 feature article in the Los Angeles Times explored the northward shift of pollock toward Russian waters, and what it could mean for the fishery. The research of Bering Sea Project scientists Franz Mueter and Jim Ianelli figured prominently in the story. See a summary of the story and link to the newspaper article.
The combination of acoustics, trawling, and oceanography gives us a powerful tool to see how fish distribute themselves in a dynamic ocean.
We can interpret these changes in the context of the overall Bering Sea Project, which seeks to understand the mechanisms creating and sustaining life in the Bering Sea.
Rapid changes seem to be occurring here: in 2008, most of young pollock were found in the top 30m of the water column, and capelin were scarce throughout the study region. Figure 1 (above) shows pollock distribution. See larger image
By 2009 pollock were not found in the near-surface waters in favor of waters near the bottom (>80m depth), and capelin occupied the upper 30m of the water column in larger, more distinctive groups. We expect 2010, predicted to be a "coldest" year, to be much the same. Figure 2 (above) shows capelin distribution. See larger image
Fish can respond to their environment and change their distribution. This affects not just the fish themselves -- young pollock's shift to deeper water puts them closer to their predators -- but the availability of a meal for surface or shallow-diving predators like black-legged kittiwakes.
Following their cruise aboard the NOAA Ship Oscar Dyson, Patrick Ressler and Mike Sigler made presentations at the Museum of the Aleutians in June 2010. The evening event was well attended by 30-40 people who took this opportunity to hear and ask questions about what science tells us is happening there now, and what changes may come in the future.
They also made presentations to pollock vessel captains and company staff at the Unisea processing plant. Mike described the Bering Sea Project, taking a pollock-centric approach because of the importance of the pollock fishery to Dutch Harbor. Patrick described the NOAA acoustic and bottom trawl surveys conducted in the southeastern Bering Sea and their role in the Bering Sea Project.
Thanks to Reid Brewer and Don Graves for organizing the events.
|Mike Sigler presentation (PDF)||Patrick Ressler presentation (PDF)|