Variation in groundfish predation on juvenile walleye pollock relative to hydrographic structure near the Pribilof Islands, Alaska
Walleye pollock ( Theragra chalcogramma ) are an important forage fish in the eastern Bering Sea ecosystem. As part of an ongoing study of the processes affecting juvenile walleye pollock recruitment in the eastern Bering Sea, a concentrated effort has been focused on the hydrographic fronts near th...
| Published in: | ICES Journal of Marine Science |
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| Main Authors: | , , , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
2000
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| Subjects: | |
| Online Access: | http://icesjms.oxfordjournals.org/cgi/content/short/57/2/265 https://doi.org/10.1006/jmsc.1999.0600 |
| Summary: | Walleye pollock ( Theragra chalcogramma ) are an important forage fish in the eastern Bering Sea ecosystem. As part of an ongoing study of the processes affecting juvenile walleye pollock recruitment in the eastern Bering Sea, a concentrated effort has been focused on the hydrographic fronts near the Pribilof Islands, Alaska, as important nursery areas for these juveniles. Diel variation in the consumption of age-0 pollock by arrowtooth flounder ( Atherethes stomias ) was examined from a series of collections at a station at the tidal front located north of St Paul Island, Alaska. Age-0 pollock were the primary prey of arrowtooth flounder throughout the day, but they were least digested in the late day, indicating a diurnal feeding pattern. A similar diurnal pattern was not seen in the vertical distribution of age-0 pollock, suggesting that the feeding pattern exhibited by arrowtooth flounder was based on their diel migratory behavior. Lengths of age-0 pollock consumed by arrowtooth flounder were similar to those sampled with midwater trawls. Walleye pollock cannibalism was examined along a transect that included samples collected at the front and offshore of the front. Age-0 fish were the primary prey (by weight) at all locations. Adjacent cohort cannibalism was prevalent (age-0 pollock were 79% of the diet by weight) at the frontal region. Estimates of age-0 pollock cannibalism rates were highest at the front for age-1 pollock and offshore for the adults. Prey selectivity analysis indicated that age-0 pollock were more highly selected offshore than at the front. |
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