CSU Fisheries Ecology Laboratory
Provenance of nonnative fishes in
the Upper Colorado River basin
Funded by U.S. Fish and Wildlife Service, Upper Colorado River Endangered Fish Recovery
Program
2001-2006
Collaborators
Patrick Martinez, Colorado Division of Wildlife
Anita Martinez, Colorado Division of Wildlife
Gregory Whitledge, Department of Zoology, Southern Illinois
University
Background/Rationale
Floodplain corridors bordering the main stem rivers in the Upper Colorado River
Basin are considered an integral and necessary element in the recovery of the
four endangered big river fish species. Nonnative fish species are
present throughout the Upper Basin (Martinez 2002, Trammel et al. 2002), and
can adversely impact the recovery progress for endangered fishes through
predation or competition at critical life stages or in critical locales (Tyus
and Saunders 1996). Four species in the Family Centrarchidae (largemouth
bass Micropterus salmoides, green sunfish Lepomis cyanellus,
bluegill Lepomis macrochirus and black crappie Pomoxis nigromaculatus)
are considered to be the most problematic.
Control of nonnative fishes has been a recovery program goal since
at least 1996, but control efforts have met with limited success, partly
because the predominant source of nonnative fish in the Colorado River is
unknown. The large number of potential sources and the inability to
determine specific habitats where nonnative fishes are reproducing and
recruiting has been a vexing problem. Managers’ work would be greatly
facilitated by knowledge of the origins and movement patterns (provenance) of
nonnative fishes, which could provide insights into the most promising and
efficient management strategies to control them. However, it has not been
possible to study nonnative fish provenance by conventional means because
physical sampling and mark-recapture techniques are inadequate given the scale
of the problem.
The advent of stable isotopic and microchemical analyses of otoliths has
provided a new avenue for the study of fish provenance by exploiting natural
markers that reflect a fish’s environmental history throughout its
lifetime. A variety of stable isotopes of common elements provide
naturally occurring markers to track origins and movements of nonnative fishes
in the upper Colorado River basin. In this study we used elemental and isotopic
analysis of water and fish otoliths to identify, for the first time, the sources
of nonnative fish found within riverine reaches of critical habitat in the
Grand Valley, Colorado.
Study Goals
Identify recruitment sources of nonnative fishes in the
Study
Objectives
1. Determine whether the origins and movements
(collectively termed provenance) of centrarchids in the study area can be
identified using stable isotope and/or microchemical analyses.
2. Determine the proportion of centrarchids in
backwaters within the study area that originated from out-of-channel ponds
versus in-channel habitats.
3. If feasible, pinpoint “hotspots” where centrarchids
present in connected backwaters have originated by narrowing the list of
possible sources (e.g. from “off-channel ponds” to specific ponds or groups of
ponds).
Publications to Date
1. Whitledge, G. W., B. M. Johnson, P. J. Martinez, and
A. M. Martinez. 2007. Sources of
nonnative centrarchids in the upper Colorado River revealed by stable isotope
and microchemical analyses of otoliths. Transactions of the American Fisheries
Society 136: 1263–1275.
2. Whitledge, G. W., B. M. Johnson and P. J.
Martinez. 2006. Stable hydrogen isotopic composition of
fishes reflects that of their environment. Canadian Journal of Fisheries and
Aquatic Sciences 63:1746-1751.
FINAL
REPORT (pdf)
Dr. Brett M. Johnson
Department of Fish, Wildlife and Conservation Biology
Colorado State University, Fort Collins, CO 80523-1474
voice: (970) 491-5002, (970) 491-2749 fax: (970) 491-5091
brett.johnson"at"colostate.edu
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