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AFSC/RACE/EcoFOCI: NPRB project number 926: Assessing the condition of walleye pollock,
Theragra chalcogramma, larvae in the eastern Bering Sea with muscle-based flow cytometry
cell cycle analysis
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Walleye pollock are an important component of the eastern Bering Sea ecosystem due
to their vast numbers and biomass and are of great commercial importance. Their recruitment
in the eastern Bering Sea is not well understood but it is largely determined during
the first year, so the larval stage may play a significant role. Starvation may contribute
to the high and variable mortality that occurs during the larval stage so it is important
to monitor and quantify it. This metadata describes data from laboratory and field
studies conducted from 2009 to 2012 for NPRB project 926. The project completed the
development of an assay using flow cytometric cell cycle analysis to assess the physiological
condition of walleye pollock larvae, and applied it to field collected specimens.
The use of RNA to improve the accuracy of the assay was also investigated, as well
as the relationship between flow cytometric measurements and growth.
Results showed that the overall classification accuracy of the assay (healthy or unhealthy)
ranged between 75 and 83% depending on the type of cross-validation testing. A nuclear
RNA variable (the ratio of the number of S phase nuclei to the number of high nuclear
RNA content G1 phase nuclei) improved overall classification accuracy by 11% compared
to a model without it. Unhealthy walleye pollock larvae were present in the southeastern
Bering Sea in 2009, and this was most likely the result of cold environmental conditions
affecting prey availability and larval feeding. In 2010, no unhealthy larvae were
detected. This may be the result of less spatial coverage and smaller collections
of larvae than in 2009, given that the environmental conditions were similar between
years.
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