**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below.  For a copy of the full completion report, please contact the author via e-mail at liweim@msu.edu. Questions? Contact the GLFC via email at frp@glfc.org or via telephone at 734-662-3209.**

A Preliminary Study on the Roles of Chemical Cues in American Eel Life History

¹Andrew Schmucker, ²Heather S. Galbraith, ³Nicholas Johnson, and ¹Weiming Li

¹Michigan State University Department of Fisheries and Wildlife480 Wilson Rd. Room 13 Natural Sciences Building East Lansing, MI 48824, USA

²USGS - Leetown Science Center Northern Appalachian Research Laboratory 176 Straight Run Road Wellsboro, PA 16901, USA

³USGS, Great Lakes Science Center Hammond Bay Biological Station 11188 Ray Road Millersburg, MI 49759, USA

September 2017

ABSTRACT:

We investigated whether American eels Anguilla rostrate emitted bile acids as conspecific cues and as potential signals for inland migration and outmigration. We used liquid chromatography-mass spectrometry to analyze the holding water (washings) and tissues of the digestive system of American eels from multiple life stages. Bile acids were identified in washings of glass eel, elver, and yellow eel. Six specific bile acids (taurochenodeoxycholic acid, taurodeoxycholic acid, cholic acid, deoxycholic acid, taurolithocholic acid, and taurocholic acid) were detected in composite (whole) tissue of American glass eel and elver and in the liver, intestine, and gall bladder tissue samples of late stage yellow eel. Notable differences were observed in washing chemical profile and bile acid concentration by life stage and organ type. Behavioral testing results support the notion that conspecific cueing is an important component of migration coordination among juvenile American eels and the responses to chemical cues may be life-stage dependent and that glass eels moving inland may use the odor of the previous year class as information to guide migration. The role of chemical cues and olfaction in eel inland migrations warrants further investigation as a potential restoration tool. However, behavioral results did not support the hypothesis that conspecific chemical cueing is a mechanism for downstream migration coordination or danger avoidance. Fisheries managers may opt to focus future research on more feasible restoration efforts using alternate experimental designs to remedy this ecological issue.