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- Title
Early- to late-summer population growth and prey consumption by age-0 pollock ( Theragra chalcogramma), in two years of contrasting pollock abundance near the Pribilof Islands, Bering Sea.
- Authors
Winter, Andreas; Swartzman, Gordon; Ciannelli, Lorenzo
- Abstract
Acoustic survey data were used to estimate the abundance and distribution of age-0 walleye pollock and zooplankton near the Pribilof Islands, Bering Sea, nursery area at two time periods in two consecutive years: the beginning of August, and mid-September, of 1996 and 1997. The 1996 pollock year class ultimately produced a large adult cohort in the eastern Bering Sea, while the 1997 year class produced a below-average adult cohort. Acoustic densities of age-0 pollock were significantly lower in August – and declined more strongly from August to September – in 1997 than in 1996, indicating that the trend to adult cohort strength was already set by August. Diet composition analyses revealed that age-0 pollock ate a much higher proportion of euphausiids in 1997 than in 1996, despite lower acoustic abundance of euphausiids in 1997. We infer that in 1996, age-0 pollock experienced greater feeding success by August, with high concentrations of copepods available for smaller fish to consume, and high concentrations of euphausiids available for larger individuals. In 1997, age-0 pollock had lower body condition in August and may have been limited by the availability of small (<2 mm) copepods. Bioenergetic modeling of prey consumption did not indicate a likelihood that age-0 pollock would begin to deplete euphausiids until late August in 1996, and not at all between August and mid-September in 1997.
- Subjects
BERING Sea; WALLEYE pollock; WALLEYE pollock fisheries; FISHERIES; THERAGRA
- Publication
Fisheries Oceanography, 2005, Vol 14, Issue 4, p307
- ISSN
1054-6006
- Publication type
Article
- DOI
10.1111/j.1365-2419.2005.00341.x