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Fishery Bulletin 113(2) 
al., 2002; Kostow 1 ; Mesa and Copeland, 2009). Pacific 
lamprey in the Columbia River have been the focus of 
much of this work because of the cultural importance 
of this species for Native American tribes in the basin 
and the documented decline in adults counted crossing 
Columbia River dams (Close et al., 2002; Moser and 
Close, 2003). In contrast, very little is known about the 
biology or status of the western river lamprey, to the 
extent that its continued existence in Oregon has been 
questioned (Kostow 1 ). 
Although there is considerable effort underway to 
understand the habitat requirements of lampreys in 
freshwater (e.g., Streif, 2009; Jackson and Moser, 2012), 
very little is known about estuarine and marine ecol- 
ogy for most lamprey populations (Mesa and Copeland, 
2009; Murauskas et al., 2013; Siwicke, 2014), including 
those in the Columbia River. Information on estuarine 
ecology is necessary to understand this fundamental 
stage of the life cycle and is essential to document the 
timing of transitions between freshwater and marine 
habitats. Lampreys can also be parasitic in estuaries, 
yet very little is known about these parasite-host rela- 
tionships outside of the Fraser River (Beamish, 1980; 
Beamish and Neville, 1995). 
To address the paucity of basic information on lam- 
preys in the Columbia River estuary, we used 2 data 
sets from the systematic sampling of the estuarine 
fish assemblage to document use of the estuary by 
western river and Pacific lampreys. We also describe 
fishes with lamprey wounds observed over a 5-year 
period. Although far from comprehensive, this work 
begins to fill a critical information gap about lam- 
preys in the Columbia River estuary and provides an 
important contribution to knowledge of the life his- 
tory of these ancient — and culturally and ecologically 
important — species. 
Materials and methods 
Fish collections 
Juvenile and adult lamprey data used in our analy- 
sis came from 2 studies: the Columbia River Estuary 
Data Development Program (CREDDP) in 1980-1981 
and the Estuary Purse Seine (EPS) study during 2001- 
2012. The CREDDP was a large, multifaceted research 
effort designed to increase understanding of the ecol- 
ogy of the Columbia River estuary. It consisted of 13 
integrated projects, ranging from quantifying benthic 
primary production to modeling circulation (Bottom et 
al. 2 ). We were able to access archived raw biological 
1 Kostow, K. 2002. Oregon lampreys: natural history, sta- 
tus, and analysis of management issues, 80 p. Oregon Dep. 
Fish Wildl. Inf. Rep. 2002-01. [Available from http://www. 
dfw.state.or.us/fish/species/docs/lampreys2.pdf.] 
2 Bottom, D. L., K. K. Jones, a nd M. J. Herring. 1984. Fishes 
of the Columbia River estuary: final report on the Fish Work 
Unit of the Columbia River Estuary Data Development Pro- 
gram, 113 p. Columbia River Estuary Data Development 
data collected by the NOAA Fisheries Northwest Fish- 
eries Science Center during this study. 
The primary fish project of CREDDP was an 
18-month-Iong effort devoted to better defining pelagic 
and demersal components of the estuarine assemblage 
(Bottom et al. 2 ). Fishes were collected monthly from 
February 1980 through July 1981 at 22 bottom trawl 
and 16 purse seine sites. One haul or set was conduct- 
ed at each site each month; therefore, the months of 
February-July were each sampled twice (once in 1980, 
once in 1981) and the months of August-January were 
sampled only once. The CREDDP included beach seine 
and fyke net sampling, but catches of lampreys in both 
gears were low (re=4) and were not included in our 
analysis. Sampling sites in the Columbia River were lo- 
cated from river km (rkm) 3.8 through rkm 58.2 (rkm 0 
is the west end of the jetties) (Fig. 1) and were chosen 
to represent a diversity of habitats within the estuary. 
A semiballoon shrimp trawl (38.1-mm stretched 
mesh, knotless 12.7-mm liner) with an 8-m head rope 
was towed upstream during flood tide for 5 min dur- 
ing CREDDP sampling. A purse seine (200x9.8 m) with 
variable knotless mesh (19.0 and 12.7 mm) was towed 
upstream for 5 min before the net was pursed (Bottom 
et al. 2 ). All collected fish were identified to species ac- 
cording to standard fish identification references (e.g., 
Hart, 1973; Scott and Crossman, 1973), enumerated, 
and released. Up to 50 individuals of each species were 
restrained or anaesthetized (juvenile salmon only), 
measured, (fork length [FL] or total length [TL] in 
millimeters, weighed (weight in grams), and released. 
Eyed lampreys were identified to species by dentition; 
ammocoetes, in which developing eyes are covered with 
skin, were grouped into a single category. 
The EPS study in the lower Columbia River estu- 
ary was conducted during 2001-2012, although no 
sampling occurred in 2004 and 2005. The study objec- 
tives during 2001-2003 were to document presence 
and abundance of forage fishes in the lower estuary 
(S. Hinton, unpubl. data), but objectives changed in 
2007 to assess presence and abundance of juvenile 
salmon, with particular emphasis on the spring outmi- 
gration (Weitkamp et al., 2012). Accordingly, sampling 
during 2001-2003 occurred twice monthly from mid- 
April through September. The sampling interval dur- 
ing 2007-2012 was highest during the spring (every 
2 weeks from mid-April through late June), with an 
additional sampling cruise in September during 2007- 
2008 and approximately monthly sampling from July 
through October during 2009-2012. The sampling dur- 
ing 2001-2003 was conducted at 4 sampling stations 
in the lower estuary (Sand Island [rkm 7], Desdemona 
Sands [rkm 16], North Channel [rkm 17], and Trestle 
Bay [rkm 13]), and the sampling during 2007-2012 was 
conducted at only 2 sampling stations (Trestle Bay and 
North Channel) (Fig. 1). Sampling depths also changed 
over the course of this study, with fish sampled in 
Program. [Available from Columbia River Estuary Study 
Taskforce, P.O. Box 175, Astoria, OR 97103.] 
