213 
NOAA 
National Marine 
Fisheries Service 
Fishery Bulletin 
ftr established 1881 -<?. 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Seasonal abundance, size, and host selection 
of western river {Lampetra ayresii ) and 
Pacific {Entosphenus tridentatus ) lampreys 
in the Columbia River estuary 
Email address for contact author: laurie.weitkamp@noaa.gov 
Abstract— Little is known about the 
basic biology and ecology of most na- 
tive lampreys, including the use of 
estuaries by anadromous lampreys. 
To address this deficiency, we pro- 
vide the first analysis of anadromous 
western river ( Lampetra ayresii ) and 
Pacific ( Entosphenus tridentatus) 
lampreys in the Columbia River es- 
tuary, using data from 2 fish assem- 
blage studies that span 3 decades 
(1980-1981 and 2001-2012). Pacific 
lamprey juveniles and adults in the 
estuary clearly were separated by 
size, whereas western river lamprey 
formed one continuous size distribu- 
tion. Pacific lamprey juveniles and 
adults were present in the estuary 
in winter and spring, and western 
river lamprey were present from 
spring through early fall. Depth 
in the water column also differed 
by lamprey species and age class. 
During 2008-2012, we documented 
wounds from lampreys on 8 fish spe- 
cies caught in the estuary. The most 
frequently wounded fishes were 
non-native American shad ( Alosa 
sapidissima), subyearling Chinook 
salmon (Oncorhynchus tshawytscha), 
shiner perch ( Cymatogaster aggre- 
gata), and Pacific herring (Clupea 
pallasii). This basic information on 
western river and Pacific lampreys 
in the Columbia River estuary adds 
to the growing body of regional re- 
search that should aid conservation 
efforts for these ancient species. 
Manuscript submitted 9 January 2014. 
Manuscript accepted 27 February 2015. 
Fish. Bull. 113:213-226 (2015). 
doi: 10.7755/FB. 113.2.9 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Laurie A. Weitkamp (contact author ) 1 
Susan A. Hinton 2 
Paul J. Bentley 2 
1 Conservation Biology Division 
Northwest Fisheries Science Center 
National Marine Fisheries Service, NOAA 
2032 Marine Science Drive 
Newport, Oregon 97365 
2 Fish Ecology Division 
Northwest Fisheries Science Center 
National Marine Fisheries Service, NOAA 
520 Heceta Place 
Hammond, Oregon 97121 
Two native lamprey species are wide- 
ly distributed along the west coast of 
North America: western river lam- 
prey ( Lampetra ayresii', formerly 
river lamprey) and Pacific lamprey 
(. Entosphenus tridentatus) (Wydowski 
and Whitney, 2003). Like most lam- 
preys (family Petromyzontidae), both 
of these species have complex life 
cycles that include an extended lar- 
val stage (the ammocoete stage) and 
a relatively brief adult stage (Hard- 
isty, 2006). Both western river and 
Pacific lampreys are anadromous and 
parasitic as adults (Beamish, 1980; 
Wydowski and Whitney, 2003); how- 
ever, many details concerning their 
life cycle and ecology are poorly un- 
derstood, and most available infor- 
mation comes from a few geographic 
areas (Beamish, 1980; Hayes et ah, 
2013). 
Pacific lamprey ammocoetes spend 
3-7 years in riverine sediments be- 
fore metamorphizing into juveniles, 
migrate downstream to spend 3-4 
years in marine waters, and spawn 
1 year after re-entering freshwater 
(Beamish, 1980; Beamish and Lev- 
ings, 1991). Compared with Pacific 
lamprey, western river lamprey have 
a much shorter ocean residence (3-4 
months), adults are much smaller, 
and timing of transitions between 
life stages differs (Beamish, 1980; 
Hayes et al., 2013). During the para- 
sitic phase, the mode of feeding also 
differs between the 2 species: Pa- 
cific lamprey consume their host’s 
blood, but western river lamprey bite 
off pieces of flesh (Cochran, 1986; 
Beamish and Neville, 1995). 
Concerns about declining native 
lamprey populations across North 
America in general (Renaud, 1997), 
and in the Columbia River in par- 
ticular (Close et al., 2002; Moser and 
Close, 2003), have led to recent ef- 
forts to restore and conserve native 
lamprey populations and identify 
specific information needed to ensure 
their continued existence (Close et 
