Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996
Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical char...
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ftoceandocs:oai:aquadocs.org:1834/31065 2023-05-15T18:32:52+02:00 Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 Shima, Michiyo Babcock Hollowed, Anne VanBlaricom, Glenn R. 2002 application/pdf 307-323 http://hdl.handle.net/1834/31065 en eng http://fishbull.noaa.gov/1002/13shimaf.pdf 0090-0656 http://hdl.handle.net/1834/31065 http://aquaticcommons.org/id/eprint/15212 403 2014-05-30 07:37:07 15212 United States National Marine Fisheries Service Ecology Fisheries Management article TRUE 2002 ftoceandocs 2023-04-06T17:04:19Z Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical characteristics, including bottom depth and distance from land. Interspecies associations were also analyzed with the Bray-Curtis clustering technique to better understand community structure. Our results indicated that although the population numbers decreased, high concentrations of pollock remained in the same areas during 1984–96. However, there was an increase in the number of stations where low-density pollock concentrations of all ages were observed, which resulted in a decrease in mean population density of pollock within the GOA region. Patterns emerging from our data suggested an alternative to Mac-Call’s “basin hypothesis” which states that as population numbers decrease, there should be a contraction of the population range to optimal habitats.During 1984–96 there was a concurrent precipitous decline in Steller sea lions in the Gulf of Alaska. The results of our study suggest that decreases in the mean density of adult pollock, the main food in the Steller sea lion diet, combined with slight changes in the distribution of pollock (age-1 pollock in particular) in the mid-1980s, may have contributed to decreased foraging efficiency in Steller sea lions. Our results support the prevailing conceptual model for pollock ontogeny, although there is evidence that substantial spawning may also occur outside of Shelikof Strait. Article in Journal/Newspaper Theragra chalcogramma Alaska IODE-UNESCO: OceanDocs - E-Repository of Ocean Publications Bray ENVELOPE(-114.067,-114.067,-74.833,-74.833) Gulf of Alaska |
institution |
Open Polar |
collection |
IODE-UNESCO: OceanDocs - E-Repository of Ocean Publications |
op_collection_id |
ftoceandocs |
language |
English |
topic |
Ecology Fisheries Management |
spellingShingle |
Ecology Fisheries Management Shima, Michiyo Babcock Hollowed, Anne VanBlaricom, Glenn R. Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
topic_facet |
Ecology Fisheries Management |
description |
Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical characteristics, including bottom depth and distance from land. Interspecies associations were also analyzed with the Bray-Curtis clustering technique to better understand community structure. Our results indicated that although the population numbers decreased, high concentrations of pollock remained in the same areas during 1984–96. However, there was an increase in the number of stations where low-density pollock concentrations of all ages were observed, which resulted in a decrease in mean population density of pollock within the GOA region. Patterns emerging from our data suggested an alternative to Mac-Call’s “basin hypothesis” which states that as population numbers decrease, there should be a contraction of the population range to optimal habitats.During 1984–96 there was a concurrent precipitous decline in Steller sea lions in the Gulf of Alaska. The results of our study suggest that decreases in the mean density of adult pollock, the main food in the Steller sea lion diet, combined with slight changes in the distribution of pollock (age-1 pollock in particular) in the mid-1980s, may have contributed to decreased foraging efficiency in Steller sea lions. Our results support the prevailing conceptual model for pollock ontogeny, although there is evidence that substantial spawning may also occur outside of Shelikof Strait. |
format |
Article in Journal/Newspaper |
author |
Shima, Michiyo Babcock Hollowed, Anne VanBlaricom, Glenn R. |
author_facet |
Shima, Michiyo Babcock Hollowed, Anne VanBlaricom, Glenn R. |
author_sort |
Shima, Michiyo |
title |
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
title_short |
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
title_full |
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
title_fullStr |
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
title_full_unstemmed |
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996 |
title_sort |
changes over time in the spatial distribution of walleye pollock (theragra chalcogramma) in the gulf of alaska, 1984-1996 |
publishDate |
2002 |
url |
http://hdl.handle.net/1834/31065 |
long_lat |
ENVELOPE(-114.067,-114.067,-74.833,-74.833) |
geographic |
Bray Gulf of Alaska |
geographic_facet |
Bray Gulf of Alaska |
genre |
Theragra chalcogramma Alaska |
genre_facet |
Theragra chalcogramma Alaska |
op_source |
http://aquaticcommons.org/id/eprint/15212 403 2014-05-30 07:37:07 15212 United States National Marine Fisheries Service |
op_relation |
http://fishbull.noaa.gov/1002/13shimaf.pdf 0090-0656 http://hdl.handle.net/1834/31065 |
_version_ |
1766217068025217024 |