Population dynamics of smallmouth bass in the beaver archipelago, northern lake michigan, 1999-2002
Seider, Michael John
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The Beaver Island Archipelago in Lake Michigan had a popular smallmouth bass (Micropterus dolomieui) fishery in the 1970-80s. In the 1990s, anglers became concerned that the smallmouth bass population was in decline due to predation by the increasing double-crested cormorant (Phalacrocorax auritus) population in the archipelago. The objective of this study was to determine the status of smallmouth bass by estimating current population characteristics and comparing them to past data. I estimated population size, condition, growth, and cohort survival for smallmouth bass from 1999-2002. Smallmouth bass abundance had declined 85-92% since the 1970-80s. Growth rates and condition had increased since the 1970s. High adult survival and similar declines in nongame fish species indicated that angler harvest was not limiting smallmouth bass abundance. Mortality rates for ages 3-5 were as high as 99%, which is consistent with cormorant predation. These data suggested that cormorant predation is limiting smallmouth bass abundance.