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Phenology of larval fish in the St. Louis River estuary
Citation:
Peterson, Greg, J. Hoffman, A. Trebitz, AND J. Lietz. Phenology of larval fish in the St. Louis River estuary. Minnesota Society of the American Fisheries Society, Duluth, MN, February 01 - 03, 2016.
Impact/Purpose:
not applicable
Description:
Little work has been done on the phenology of fish larvae in Great Lakes coastal wetlands. As part of an aquatic invasive species early detection study, we conducted larval fish surveys in the St. Louis River estuary (SLRE) in 2012 and 2013. Using multiple gears in a spatially balanced random design, we collected >130 samples each year over an approximately 8-week period from May through July. Fish larvae were identified to the lowest taxonomic level possible and staged (yolk-sac, pre-flexion, flexion, post-flexion). To describe seasonal patterns and compare results between years, we evaluated the occurrence of fish species and larval stage with respect to Julian Day, water temperature, and growing degree days. We found distinct seasonal assemblage patterns, which likely reflect differences in adult spawning temperature preferences. Further, there were significant differences among species with respect to the likelihood of encountering larvae in different sampling gear and at different stages. These results inform larval fish ecology survey designs and will serve as a benchmark to assess future changes in larval fish phenology in the SLRE.