. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . Figure 33-15. Locations of individuals observed in spawn- ing condition during April-June 1976. Dots siiow exact positions, siiading indicates inferred range of spawning activities. spawning probably occurs along the entire eastern Bering Sea shelf edge, the outer shelf region just west and northwest of Unimak Island has been repeatedly identified as a major reproductive site (Maeda 1972, Maeda and Hirakawa 1977, Serobaba 1968, 1974). Trawl fisheries target upon pre- spawning and spawnin
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . Figure 33-15. Locations of individuals observed in spawn- ing condition during April-June 1976. Dots siiow exact positions, siiading indicates inferred range of spawning activities. spawning probably occurs along the entire eastern Bering Sea shelf edge, the outer shelf region just west and northwest of Unimak Island has been repeatedly identified as a major reproductive site (Maeda 1972, Maeda and Hirakawa 1977, Serobaba 1968, 1974). Trawl fisheries target upon pre- spawning and spawning populations, obtaining high catch rates. Some fishing vessels harvest pollock only for roe, discarding their catches after stripping the ovaries from ripe females. Schools of pre-spawning and spawning pollock apparently move high into the water column, forming dense midwater layers (Takakura 1954, Serobaba 1974). Mating presumably involves pairing, and broadcasting of the pelagic non-adhesive eggs (ca. mm in diameter) with no parental care. Consis- tent with reported locations of principal spawning areas, pollock eggs and larvae have been observed in highest concentrations along the outer continental shelf between the Pribilof Islands and Alaska Penin- sula (Serobaba 1968, Waldron and Vinter 1978). Although some studies of the early life history of pollock in the eastern Bering Sea have presupposed a simple counterclockwise current transport through the central shelf region during the first one or two years of age, recent data suggest a different and more complex pattern of movement (Figs. 33-16 and 33-17). As opposed to the previous impression of predominantly counterclockwise water motion over the eastern Bering Sea shelf, the present concept of
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