Effects of year and region on the abundance and size of age-0 walleye pollock, Theragra chalcogramma, in the western Gulf of Alaska, 1985-1988
Wilson, M.T. (2000). Effects of year and region on the abundance and size of age-0 walleye pollock, Theragra chalcogramma, in the western Gulf of Alaska, 1985-1988. Fish. Bull. 98(4): 823-834
In: Fishery Bulletin. US Government Printing Office: Washington, D.C.. ISSN 0090-0656; e-ISSN 1937-4518, more
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| Abstract |
Effects of year and region on young-of-the-year (age-0) walleye pollock abundance and size were examined by using bottom and midwater trawl collections made during 1985-88. Samples were collected from shelf and coastal areas in three adjacent regions of the western Gulf of Alaska. The primary focus was to examine regional differences in recruitment prediction and annual differences in fish distribution. Fish density was used to indicate abundance, and length was included as a relevant factor in fish production. Year and region significantly interacted as effects on age-0 density. Recruitment prediction was best in the Kodiak Island region, upstream of the main spawning area, where fish densities were high during 1985 and 1988 in relation to 1986 and 1987. On a large scale, fish were evenly distributed every year, except during 1987 when their density increased strongly from east to west. Age-0 length also varied with year and region. This was apparent after accounting for daily increases in mean length (0.09 cm/d). Fish were comparatively small during 1986, intermediate during 1985, and large during 1987 and 1988. Regional differences in fish length were due to a relative abundance of large-size fish around Kodiak Island where the average size was about 0.75 cm larger than elsewhEire. Thus, a relative abundance of large individuals in this region was associated with good recruitment prediction. These results are discussed in terms of their relevance to spatial variation in the production of recruits. |
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