Vital Statistics and Migratory Patterns of a Potamodromous Stock of Smallmouth Bass, Micropterus dolomieui

Abstract
Between 1968 and 1971, upriver movement of bass from Lake Simcoe was highly correlated with water temperature and discharge (r = 0.704, P <.001). Vital statistics and growth were similar to lacustrine and riverine stocks at similar latitude. Total annual mortality averaged 0.56 with 65% attributable to angler exploitation, principally in the river. Some 34% (after mortality) river spawners returned upriver in subsequent years. Repeat spawners (65% female) comprised an average 19% of the spawning runs. Most adults moved downriver in late June and July when water temperatures approached 25 °C. Adults remaining in the spawning area experienced water temperatures to 29 °C before emigrating during freshets in July and August. Lake migrants intermingled on shoal areas with lacustrine and possibly other potamodromous stocks each summer.

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