**The title, authors, and
abstract for this completion report are provided below. For a copy of the
completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**
Assessment Of Otolith Chemistry As An Indicator Of Fish Movement Or
Transfer Between The Illinois River System And Lake Michigan
January 2008
Gregory W.
Whitledge
Fisheries and Illinois Aquaculture Center
Southern
Illinois University
Carbondale, IL
62901-6511
ABSTRACT:
Naturally
occurring chemical markers in otoliths offer a potential means to identify
source environment for fishes in the upper Illinois River system and Lake Michigan, including individuals that may breach
electrical barriers in the Chicago Sanitary and Ship Canal or be transferred
via bait buckets between these formerly isolated drainages. The objectives of this study were to determine
whether water and fish otolith stable isotopic and elemental compositions
differ among Lake Michigan, the upper Illinois River, and three tributaries of
the upper Illinois River (Fox, Des Plaines and DuPage Rivers) and to determine
whether otolith isotopic and elemental signatures could be used to identify the
water body from which individual fish were collected. Water and fish otolith samples were obtained
from each site during summer 2007 and
analyzed for δ18O and a suite of trace element concentrations;
otoliths were also analyzed for δ13C. Otolith
δ13C values for Lake Michigan fish were distinct from individuals
collected in the Illinois River and
tributaries. Fish collected in the Fox
and Des Plaines Rivers could be distinguished from one another and from fish
captured in the Illinois and DuPage Rivers using otolith Sr:Ca and Ba:Ca ratios. Otoliths reflected differences in water Sr:Ca and Ba:Ca among environments. Otolith
isotopic and elemental compositions may enable determination of source
environment for any Asian carp discovered in Lake Michigan and could also be
useful as indicators of environmental history for fishes in the upper Illinois
River and its tributaries.