Loch, J. J. and S. A. Bonar (1999).  Occurrence of grass carp in the Lower 
Columbia and Snake Rivers. Transactions of the American Fisheries Society.  
128:374-379.
	
Forty-nine adult grass carp Ctenopharyngodon idella were observed migrating 
upriver past Lower Columbia and Snake river hydroelectric dams between August 1, 
1996, and September 30, 1997, representing the first recorded sightings of this 
fish species in this system. From videotape records and visual counts, grass 
carp were estimated to range between 55 and 77 cm in total length (TL). One 7.7-
kg, 86-cm individual captured in a gill net was identified as a sterile 
triploid. Although the source of these fish is unknown, their appearance in the 
Columbia and Snake rivers might have been related to extensive flooding that 
occurred in western Washington and Oregon in February 1996. The unintentional 
escape of grass carp into this large river system reemphasizes the need for the 
current requirement that all grass carp stocked in Pacific Northwest lakes be 
sterile triploids. It also suggests that increased attention to effective 
barrier construction and maintenance is important to prevent grass carp impacts 
in nontarget areas.