We will estimate midwater walleye pollock (age 1+) abundance in the eastern Bering Sea through acoustic-trawl surveys conducted by NOAA Alaska Fisheries Science Center.
Collection of observations of physical oceanography, fish prey fields, and marine mammal and seabirds for related Bering Sea Project work will also take place during these summer cruises.
We will quantify forage fish (e. g. , juvenile pollock, capelin, herring, and myctophids) distribution on the Bering Sea shelf, and examine how oceanography and climate forcing may influence forage fish distribution, abundance, and ultimately effect apex predator distribution and abundance. We will add acoustics and midwater trawling to document density distribution of forage species, and will map forage species distribution and compare distributions and abundances among survey years.
We will conduct a retrospective analysis of ichthyoplankton catches of pollock, cod, and arrowtooth flounder and wintertime fisheries data to create species spawning distribution models.
We will provide biological and physical data on the food habits of groundfish relative to predator and prey fields. We will use this information to evaluate whether competition for common prey or predator avoidance influences the spatial and temporal distribution of forage fish. Understanding these processes will provide the information needed to build computer models to assess the potential impact of climate change on forage fish movement and seasonal distribution.
We will provide biological and physical data from a commercial fishing vessel, acoustic surveys and bottom trawl surveys. We will use this information to identify the processes influencing the spatial and temporal distribution of forage fish, their predators and competitors relative to ocean habitat conditions and to evaluate hypotheses regarding the potential impact of climate change on forage fish movement and seasonal distribution.
The Alaska Fisheries Science Center conducts annual surface (epi-pelagic) trawl surveys to monitor the condition of the eastern Bering Sea continental shelf epi-pelagic fish community. This survey is funded with in-kind money and will support BEST-BSIERP by providing biological and environmental survey data to other PIs in the program.
The NOAA Alaska Fisheries Science Center conducts annual bottom (benthic) trawl surveys to monitor the condition of the eastern Bering Sea continental shelf epi-benthos. This survey is funded with in-kind money and will support BEST-BSIERP by providing biological and environmental survey data to other PIs in the program.
Bering Sea Project investigator Bob Lauth reports that researchers from NOAA's Alaska Fisheries Science Center finished the 29th in a series of standardized annual bottom trawl surveys of the eastern Bering Sea (EBS) continental shelf. This year the F/V Alaska Knight and F/V Aldebaran were chartered from 2 June to 4 August to bottom trawl the standard survey area consisting of 376 stations covering an area of 144,493 square nautical miles.
Survey results are used in the management of groundfish (including pollock) and crab, and in researching ecological and physical factors affecting groundfish and crab distribution and abundance.
A data logger was attached to the trawl to obtain temperature information for the survey area (left). See larger image
The 2010 bottom temperatures ranged from –1.6° to 6.4°C and the plotted bottom temperatures in the figure show that a well defined cold pool (< 2°C) occupied most of the mid-shelf at depths between 50 and 100 m.
Warmer bottom temperatures occurred in the inner shelf south of Nunivak Island and along the outer shelf. The mean bottom water temperature of the entire shelf for the survey period (1.4°C) was slightly higher than the previous summer (1.2°C), but still well below the long-term mean for 1982 to 2009 (2.4°C).