Early Life History Ecology of Fishes with Comparisons Between Great Lakes and Marine Systems

Fisheries scientists have long recognized the importance of the dynamics of early life stages for setting year class strength.  In this review, we first determined the biological traits that control larval fish feeding and mortality and then compared biological differences between Great Lakes and marine fishes.  We found that life history traits such as egg size, egg density, and larval size can influence starvation and predation mortality, as well as the timing of density-dependent mortality.  In general, Great Lakes fishes have larger, denser eggs and thus have larger, more developed larvae than marine species.  Next, we summarized influential hypotheses of mortality of early life history stages, including Hjort’s Critical Period hypothesis and Cushing’s Match-Mismatch hypothesis.  Although developing one overarching early life history paradigm is appealing, a single explanation for variation in year class strength is inappropriate for most populations, let alone for explaining year class strength variation for multiple species across systems.  Finally, we reviewed recent early life history studies from Great Lakes and marine systems.  Recent advances in technology and data availability have allowed for a greater ability to link environmental factors to mortality of early life stages and subsequent year class strength.