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Vertical migration and nighttime distribution of adult bloaters in Lake Michigan

Transactions of the American Fisheries Society

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Abstract

The vertical migration and nighttime vertical distribution of adult bloaters Coregonus hoyi were investigated during late summer in Lake Michigan using acoustics simultaneously with either midwater or bottom trawling. Bloaters remained on or near bottom during the day. At night, bloaters were distributed throughout 30-65 m of water, depending on bottom depth. Shallowest depths of migration were not related to water temperature or incident light. Maximum distances of migration increased with increasing bottom depth. Nighttime midwater densities ranged from 0.00 to 6.61 fish/1,000 mA? and decreased with increasing bottom depth. Comparisons of length distributions showed that migrating and nonmigrating bloaters did not differ in size. However, at most sites, daytime bottom catches collected a greater proportion of larger individuals compared with nighttime midwater or bottom catches. Mean target strengths by 5-m strata indicated that migrating bloaters did not stratify by size in the water column at night. Overall, patterns in frequency of empty stomachs and mean digestive state of prey indicated that a portion of the bloater population fed in the water column at night. Bloater diet composition indicated both midwater feeding and bottom feeding. In sum, although a portion of the bloater population fed in the water column at night, bloaters were not limited to feeding at this time. This research confirmed that bloaters are opportunistic feeders and did not fully support the previously proposed hypothesis that bloater vertical migration is driven by the vertically migrating macroinvertebrate the opossom shrimp Mysis relicta.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Vertical migration and nighttime distribution of adult bloaters in Lake Michigan
Series title:
Transactions of the American Fisheries Society
Volume
128
Issue:
3
Year Published:
1999
Language:
English
Contributing office(s):
Great Lakes Science Center
Description:
p. 459-474
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
459
Last page:
474
Number of Pages:
15