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- Title
Seasonal changes in the diel vertical migration of walleye pollock ( Theragra chalcogramma) in the northern Gulf of Alaska.
- Authors
Adams, Charles F.; Foy, Robert J.; Kelley, John J.; Coyle, Kenneth O.
- Abstract
Walleye pollock ( Theragra chalcogramma) perform diel vertical migration (DVM) as juveniles, but have an increasing tendency to be associated with the bottom with age. We studied the DVM of a local population of adult pollock in the northern Gulf of Alaska in August and November 2003. There was no relationship between the depth of pollock and the isolume (line of equal light intensity) necessary for visual foraging in August. Pollock passed through the thermocline at this time. In November there was a significant relationship between pollock biomass above/below the 200 m isobath and the isolume necessary for visual foraging. It is hypothesized that in August pollock ignore the isolume and thermocline, simply tracking the movements of their prey (euphausiids) to feed upon them near the surface at night. In November, relatively denser pollock shoals migrate up and down with the isolume necessary for visual foraging to feed on decapods.
- Subjects
GULF of Alaska (Alaska); ALASKA; WALLEYE pollock; FORAGING behavior; DECAPODA; POLLOCK; BANKS (Oceanography); VERTICAL distribution (Aquatic biology)
- Publication
Environmental Biology of Fishes, 2009, Vol 86, Issue 2, p297
- ISSN
0378-1909
- Publication type
Article
- DOI
10.1007/s10641-009-9519-y