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Yield and dynamics of destabilized chub (Coregonus spp.) populations in Lakes Michigan and Huron, 1950-84

Canadian Journal of Fisheries and Aquatic Sciences

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Abstract

Deepwater ciscoes (Coregonus spp.) or 'chubs' of Lake Michigan far surpassed those of Lake Huron in yield, population density, and resilience following severe depletion in the 1960s and 1970s, when the bloater (C. hoyi) composed more than 90% of the stocks. The population decline of bloaters in recent decades was mainly attributed to exploitation, to the depression of chub recruitment (e.g. from inferred predation on early life stage) by nonendemic alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax), and to complications arising from extreme female predominance that was best documented for Lake Michigan. The various interactions between bloaters and the nonendemic species, which were intensified after the loss of large predators to sea lamprey (Petromyzon marinus), would help to explain why a stock-recruitment relation was not shown for the Lake Michigan bloater. We hypothesize that reproductive inefficiency caused by a shift to strong female predominance in the bloater depresses recruitment and thus helps to regulate abundance. However, the low resilience that sex imbalance seems to impart makes the stock unstable when exploited. It should therefore be exploited conservatively during such periods. Also, the sex ratio and its direction of change appear to be important qualifiers when surplus production is estimated from stock size.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Yield and dynamics of destabilized chub (Coregonus spp.) populations in Lakes Michigan and Huron, 1950-84
Series title:
Canadian Journal of Fisheries and Aquatic Sciences
Volume
44
Issue:
Suppl. 2
Year Published:
1987
Language:
English
Contributing office(s):
Great Lakes Science Center
Description:
p. 371-383
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Fisheries and Aquatic Sciences
First page:
371
Last page:
383