Exploration of Mechanisms Regulating Larval Survival in Lake Michigan Bloater: A Recruitment Analysis Based on Characteristics of Individual Larvae

Abstract
Estimates of relative egg deposition and larval abundance suggest that events occurring between spawning and the first 1–2 months after hatching play a major role in determining recruitment success of bloater Coregonus hoyi in Lake Michigan. Although relative egg deposition in 1983 was only 57% of that in 1982, larval recruitment was 2.4 times greater in 1983. We investigated mechanisms governing survival of larval bloaters by comparing characteristics of individual “survivors” through the first 1–2 months of life with those of larvae at earlier life history stages. Otolith analysis was used to identify stress periods and to determine ages, first-feeding dates (close correlates of birthdate), and average growth rates of individual bloater larvae from hatching to nearly 2 months of age in 1982 and 1983. Differences between the observed distribution of first-feeding dates for newly hatched larvae and the expected distribution predicted from egg deposition showed that eggs spawned early experienced ...

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