کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4538193 | 1626500 | 2007 | 16 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Variations in age-0 pollock distribution among eastern Bering Sea nursery areas: A comparative study through acoustic indices Variations in age-0 pollock distribution among eastern Bering Sea nursery areas: A comparative study through acoustic indices](/preview/png/4538193.png)
Cohort abundance of walleye pollock (Theragra chalcogramma) is subject to strong interannual variation in the eastern Bering Sea, and this variation is known to be determined largely at the age-0 stage. We estimated the spatial distributions and densities of age-0 walleye pollock in five nursery areas around the eastern Bering shelf in three successive years (1997–1999) from acoustic survey data. Concurrently, we calculated estimates of the spatial distribution of euphausiids, a major prey of age-0 walleye pollock, and estimates of spatial overlap of groundfish predators with the age-0 walleye pollock. The analyses showed that all nursery areas had low densities of age-0 walleye pollock in 1997, which ultimately produced the weakest adult year-class. In the intermediate year of 1998, age-0 densities were low to medium, and in 1999, which produced the strongest of the three adult year-classes, all nursery areas had medium to high age-0 walleye pollock densities. Euphausiid distributions had a consistently positive spatial relationship with age-0 walleye pollock. Groundfish predator density ratios were positively related to age-0 walleye pollock density when age-0 walleye pollock were displaced relatively northward. Our results suggest that abundance of age-0 walleye pollock, and hence of adult cohorts in the eastern Bering Sea, can be predictable from a concise set of indicators: the densities of age-0 walleye pollock at nursery areas in mid- to late-summer, their spatial relationship to euphausiids and groundfish predators, and the latitudinal trend of their distributions. The 3 years 1997–1999 had significant differences of physical conditions in the eastern Bering Sea, and represent an advantageous framework for testing these hypotheses.
Journal: Deep Sea Research Part II: Topical Studies in Oceanography - Volume 54, Issues 23–26, November–December 2007, Pages 2869–2884