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Resource Ecology & Ecosystem Modeling Program

Arrowtooth Flounder Diets in the Eastern Bering Sea and Gulf of Alaska, 2007–10

Figure 1.  Summer diet composition, by weight (%W), of arrowtooth flounder from recent years in the eastern Bering Sea and Gulf of Alaska.


The arrowtooth flounder (Atheresthes stomias) is an ecologically important predator in the eastern Bering Sea and the Gulf of Alaska, and stomach samples are regularly collected from this species during resource surveys in Alaskan waters. Here we present the gravimetric diet composition (% weight) for different size-categories of arrowtooth flounder from 2007–10 summer surveys in the eastern Bering Sea, and from 2007 and 2009 surveys in the Gulf of Alaska (Fig. 1). The tendency for arrowtooth flounder to become more piscivorous with increasing size is consistent among years in both regions. Euphausiids and shrimp generally decrease as a percentage of the weight of the stomach contents, with increasing size of arrowtooth flounder. In the eastern Bering Sea, walleye pollock is the dominant fish prey, and the identifiable fishes in the miscellaneous fish category typically shift from stichaeids to zoarcids to pleuronectoids with increasing size of arrowtooth flounder. In the Gulf of Alaska, osmerid and clupeid prey is consistently important, and the identifiable fishes in the miscellaneous fish category are more variable, but stichaeids and pleuronectoids are prevalent. Instances of cannibalism, although fairly rare in arrowtooth flounder, were more frequent in the Gulf of Alaska than in the eastern Bering Sea. Unexpectedly, the low percentage of euphausiid prey in 2009 in the eastern Bering Sea coincides with the peak of euphausiid abundance found by AFSC hydroacoustic surveys from 2004 through 2010.

By Troy Buckley and Sean Rohan
 

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