Thermal and Physical Reproductive Cues for Spotted Gar in a Lake Erie Coastal Wetland

Session: 09. - Modeling, Detecting, and Managing Rarity

Andrew Drake, Fisheries and Oceans Canada, [email protected]
William Glass, Fisheries and Oceans Canada, [email protected]

Abstract

Understanding the environmental cues associated with reproduction can be used to predict spatial and temporal variation in hatch and resulting year-class strength, but reproductive cues are poorly known for many freshwater fishes. To quantify the thermal and physical factors associated with spawning, adult Spotted Gar (Lepisosteus oculatus) were tracked using radiotelemetry throughout a 6 week period in Rondeau Bay, Lake Erie.  The onset of spawning activity was predicted temporally via cumulative growing degree days (CGDD), where a 90% probability of spawn initiation occurred at 291 CGGD10 and 85 CGDD15. Cumulative degree days of base 10 provided slightly better predictive performance than base 15, but both models had high overall classification rates (96.3% and 94.9%, respectively). Physical factors associated with site selection estimated via boosted regression trees indicated that the proximity of the spawning site from the shoreline, the ratio of Potamogeton spp. to site volume, dominant substrate, and water depth were important variables. Future research will evaluate the influence of these factors on young-of-year survival and growth, thereby providing a mechanistic link between environmental influences and mortality of early life stages. 

1. Keyword
fish populations

2. Keyword
coastal wetlands

3. Keyword
fish behavior