Is Variation in Internal State or Variation in Environmental Reproductive Cues More Important in Driving Skip Spawning in a Tropical Estuarine Piscivore Population?

Many exploited fishes exhibit poor stock-recruitment relationships, which can make harvest estimations and conservation strategies difficult.   One factor that may be contributing to these poor stock-recruitment relationships is that some sexually mature individuals in a population forgo spawning in a given reproductive season, or skip spawn. Skip spawning has often been attributed to variation in the internal state or age and size of species. However, how variations in external drivers, such as changes in environmental cues fish use to recognize important spawning windows, influence skip spawning is understudied. In sub-tropical South Florida, precipitation varies seasonally across a rainy and a dry season, however the dynamics hydrologic seasons unpredictably vary across years, potentially affecting hydrologic cues river fish use to spawn. In this study we tracked the spawning migrations of a large-bodied tropical fish Common Snook, across four different hydrologic years from 2012-2015. We compared whether variations in wet season hydrology or internal state (condition) and pre-spawn food availability were better predictors of annual skip spawning in snook. We will discuss the implications for improving stock assessments for tropical species based off of our findings from this study.