LOWER COLUMBIA RIVER 

AQUATIC NONINDIGENOUS 

SPECIES SURVEY 

2001-2004

Final Technical Report 

Mark D. Sytsma 

Center for Lakes and Reservoirs 

Portland State University 

Portland OR 97207 

Jeffery R. Cordell 

Wetland Ecosystem Team 

University of Washington 

Seattle WA 98195 

John W. Chapman 

Hatfield Marine Science Center 

Oregon State University 

Newport OR 97365 

Robyn C. Draheim 

Center for Lakes and Reservoirs 

Portland State University 

Portland OR 97207 

Prepared for the 

UNITED STATES COAST GUARD 

and the 

UNITED STATES FISH AND WILDLIFE SERVICE 

October 2004 

 
Executive Summary 

The National Invasive Species Act of 1996 identified the need to conduct an ecological 

survey of aquatic nonindigenous species (ANS) in the Columbia River and authorized 

funding for this purpose. The Lower Columbia River Aquatic Nonindigenous Species 

Survey (LCRANS) was initiated to provide comprehensive information about the 

nonnative species present in the lower Columbia River. A comprehensive list of 

nonnative species distribution is the first step to understanding invasions, assessing 

impacts, and developing effective management actions. This investigation provides a 

baseline for evaluating the rate of species introductions to the river that will allow 

assessment of the efficacy of ballast water management regulations and contribute 

important new information to ongoing regional aquatic nonindigenous species (ANS) 

studies. Despite the considerable volume of shipping received by the five major 

freshwater and brackish ports on the lower Columbia River it had not been previously 

surveyed explicitly for nonnative species. 

The objective of the LCRANS was to provide a comprehensive survey and analysis of all 

ANS present in the tidally influenced, 234-kilometer reach of the lower Columbia River 

from Bonneville Dam to the Pacific Ocean and the tidal portions of the major tributaries. 

The project included a review of literature, conducted in 2001-2002, and field surveys,

conducted in 2002-2003. 

Due to the size and diversity of habitats the taxonomic scope of the LCRANS, field 

surveys were limited to free-living plants and animals. The geographic area surveyed 

encompassed brackish and freshwater marshes, low salinity mudflats, polyhaline beaches, 

rocky shorelines, protected embayments, large river habitats, tidally influenced 

agricultural drainages, and urban sloughs. 

We sampled at 134 stations and documented 269 aquatic species (and 55 other distinct 

organisms that we were unable to identify at the species level) in the lower Columbia 

River. Of the 269 species identified, 54 (21%) were introduced, 92 (34%) were native, 

and 123 (45%) were cryptogenic. 

LCRANS page i 
The literature review and field survey revealed that at least 81 organisms have been 

introduced into the lower Columbia River since the mid 1800s. The majority of these 

species were fish (28%), aquatic plants (23%) and crustacea (15 %). The remaining 18% 

was a combination of mollusks, annelids, bryozoans, cnidaria, amphibians, reptiles and 

an aquatic mammal. Due to the limitations of this survey, inadequate taxonomic 

resolution in prior studies, and the abundance of unresolved and cryptogenic taxa, our 

results are likely a conservative estimate of the ANS invasion of the lower Columbia 

River. 

From the 1880s to the 1970s a new introduced species was discovered in the lower 

Columbia about every five years. The frequency of new discoveries ANS is increasing 

worldwide (OTA 1993, Ruiz et al. 2000), however, and the rate of discovery of 

introduced invertebrates in the lower Columbia River mirrors this trend. Over the past 

ten years a new invertebrate species was discovered about every five months. The 

increasing rate of new discovery is due to increasing frequency of introductions and to 

the number and type of surveys conducted. It is not possible to separate these effects 

from the available data. 

In contrast to the increasing rate of invertebrate discovery, the rate of fish discovery 

peaked in the 1950s. This trend was likely due to a decline in intentional fish 

introductions by both individuals and fish and game agencies to increase the diversity of 

food and game fishes. 

The majority of introduced species in the lower Columbia originated in North America. 

Introduced fish accounted for most of the species with North American origin, while Asia 

was the native region of 34 percent of the invertebrates introduced via shipping 

mechanisms in the Columbia River. The high proportion of Asian invertebrates in the 

Columbia River fauna may be related to shipping patterns. Asian ports are the last port 

of call for most arrivals to the Columbia River from outside the Exclusive Economic 

Zone (EEZ). These patterns, however, are based on estimates of both origin and vectors 

of dispersal. For many species precise vectors and origins remain uncertain. 

The Columbia River receives more port calls from vessels from domestic ports (59 

percent) than it does from international ports (Flynn and Sytsma 2004). About 25 percent 

LCRANS page ii 
of coastal vessel traffic entering Oregon estuaries originated in the highly invaded San 

Francisco Bay/Sacramento/San Joaquin Delta (Flynn and Sytsma 2004). Short transit 

times, established populations of introduced invertebrates possibly selected for dispersal 

by shipping vectors in several domestic ports on the West Coast, and abundant shipping 

traffic suggests that domestic shipping is a highly important vector for ANS introduction 

to the Columbia River. 

This report establishes a baseline on ANS in lower Columbia River. Additional 

monitoring and sampling is necessary to detect new invasions and to document invasion 

rate, impacts, and efficacy of management efforts. We recommend a multiple-purpose

sampling approach to maximize the potential of detecting additional species and new 

arrivals. Sampling should target habitats and taxa that are likely to contain new invaders 

every year; a synoptic survey of the lower Columbia River should be conducted every 

five years; and additional sampling should target data gaps and survey limitations of this 

project. 

LCRANS page iii 
Acknowledgements 

Funding of this project by the U.S. Coast Guard and U.S. Fish and Wildlife Service was 

stimulated by the Columbia River Aquatic Nuisance Species Initiative, a joint effort by

the Ports of Portland and Astoria and the Columbia River Steamship Operators 

Association. Rich Everett, Denny Lassuy, Paul Heimowitz, and Stephen Phillips 

facilitated the project. The Technical Advisory Committee assisted with the literature 

review, reviewed draft reports, and provided sampling and analysis advice when needed. 

The project could not have been completed without the assistance of consulting 

taxonomists: Leslie Harris, Terry Frest, Jennifer Parsons, Jin Hwan Lee and Steve Fend. 

Selene O’Dell, April Fong, Laura Johnson, Mary Pfauth, Jeff Adams, Bruce Sutherland, 

Dennis Issacson, Chris Kodadek’s summer 2002 aquatic science class, Christy 

McDonough, Dr. and Mrs. Richard Peterson, Diane Kightlinger, and Kurt Getsinger 

provided valuable volunteer assistance in the field. 

LCRANS page iv 
Table of Contents: 

Executive Summary............................................................................................................. i 

Acknowledgements............................................................................................................ iv 

List of Figures.................................................................................................................... vi 

List of Tables.................................................................................................................... vii 

List of Abbreviations and Acronyms...............................................................................viii 

List of Abbreviations and Acronyms...............................................................................viii 

Chapter 1: Introduction....................................................................................................... 1 

Overview......................................................................................................................... 1 

Structure and Scope ........................................................................................................ 3 

Chapter 2: The Lower Columbia River .............................................................................. 4 

The Lower Columbia River Basin .................................................................................. 4 

The Changing Nature of Invasions................................................................................. 8 

Introductions................................................................................................................. 11 

Vectors...................................................................................................................... 12 

Pathways................................................................................................................... 18 

Chapter 3: Literature Review............................................................................................ 19 

Methods......................................................................................................................... 19 

Results........................................................................................................................... 20 

Database.................................................................................................................... 20 

Literature Review...................................................................................................... 20 

Chapter 4: Field Sampling ................................................................................................ 25 

Methods......................................................................................................................... 25 

Locations....................................................................................................................... 25 

Techniques.................................................................................................................... 26 

Classification of species................................................................................................ 30 

Chapter 5: Results and Discussion.................................................................................... 33 

Field Survey Results..................................................................................................... 33 

Literature Review and Field Survey Results ................................................................ 35 

Patterns of Introduction................................................................................................. 42 

Rates of Invasion........................................................................................................... 45 

Vectors and Pathways................................................................................................... 46 

Chapter 6: Conclusions and Recommendations ............................................................... 50 

Additional surveys........................................................................................................ 51 

Targeted sampling..................................................................................................... 51 

Discrete sampling...................................................................................................... 52 

Synoptic surveys....................................................................................................... 53 

Research Needs............................................................................................................. 53 

Management Needs....................................................................................................... 54 

References......................................................................................................................... 56 

Appendices [Bound Separately] 

Appendix A: Technical Advisory Committee Participants 

Appendix B: Species Descriptions 

LCRANS page v 
List of Figures 

Figure 1. The LCRANS study area – the tidally influenced portions of the lower 

Columbia and Willamette Rivers................................................................................ 4 

Figure 2. Habitat alteration along the Columbia River estuary .......................................... 7 

Figure 3. Past and present flow data for the lower Columbia River collected at the 

Bonneville Dam. . ...................................................................................................... 7 

Figure 4. LCRANS sampling locations 2002, 2003 ......................................................... 28 

Figure 5. Distribution of LCRANS sample types 2002-2003........................................... 29 

Figure 6. LCRANS field survey species collections broken down by major taxonomic 

group and origin........................................................................................................ 33 

Figure 7. LCRANS field survey species collections broken down by minor taxonomic 

group and origin........................................................................................................ 34 

Figure 8. Number of introduced species in various taxa in the lower Columbia River from

the literature review and field survey........................................................................ 36 

Figure 9. Comparison of invasive species in several North American systems. .............. 44 

Figure 10. Accumulation of non-indigenous species in the lower Columbia by year of 

discovery................................................................................................................... 45 

Figure 11 Changes in invertebrate introduction vectors over time................................... 47 

LCRANS page vi
List of Tables 

Table 1. Principal biological surveys of the lower Columbia River consulted by the 

literature review. ....................................................................................................... 22 

Table 2. Summary of nonindigenous and cryptogenic species compiled during the 

literature review,listed by major taxonomic category............................................... 23 

Table 3. Criteria for introduced species............................................................................ 31 

Table 4. Invasion dates and mechanisms of introduction for all introduced species in the 

lower Columbia River............................................................................................... 37 

Table 5. West Coast distributions of all introduced invertebrates found in the lower 

Columbia River......................................................................................................... 43 

Table 6. Suggested sampling locations proposed for targeted sampling. ......................... 52 

LCRANS page vii 
List of Abbreviations and Acronyms 

ANS Aquatic Nonindigenous Species 

BSWQP Bi-State Water Quality Program

CREDDP Columbia River Estuary Data Development Project 

CREST Columbia River Estuary Studies Taskforce 

IUCN The World Conservation Union also known as the International Union 

For Conservation of Nature and Natural Resources 

LCRANS Lower Columbia River Aquatic Nonindigenous Species Survey 

LCREP Lower Columbia River Estuary Project 

NAISA National Aquatic Invasive Species Act, 1996 

NMFS National Marine Fisheries Service, also known as NOAA Fisheries 

NOAA National Oceanic and Atmospheric Administration 

ODEQ Oregon Department of Environmental Quality 

ODFW Oregon Department of Fish and Wildlife 

OSU Oregon State University 

OTA Office of Technology and Assessment 

SERC Smithsonian Environmental Research Center 

TAC Technical Advisory Committee (part of LCRANS) (see Appendix A) 

USACE United States Army Corps of Engineers 

USFC United States Fish Commission (predecessor to USFWS and NOAA 

Fisheries) also known as United States Commission of Fish and Fisheries 

USFWS United States Fish and Wildlife Service 

WEMAP West Coast Environmental Monitoring and Assessment Program

WDE Washington State Department of Ecology 

WDFW Washington Department of Fish and Wildlife

LCRANS page viii 
Chapter 1: Introduction 

Overview 

Rates of aquatic nonindigenous species (ANS) introductions and their social, economic, 

and ecological impacts are increasing (OTA 1993, Ruiz et al. 2000). Introductions of 

nonnative marine organisms have increased exponentially over the last two centuries and 

expenditures on outreach, control, and research exceed millions of dollars per species for 

several invaders of particular concern to the United States (Carlton 2001)1

. These trends 

suggest that major changes are occurring in the freshwater, estuarine, and marine 

ecosystems of North America (OTA 1993, Cohen and Carlton 1995), but their magnitude 

is probably underestimated. For every well-documented impact of notorious invaders, 

such as intake-pipe fouling by the zebra mussel,Dreissena polymorpha (OTA 1993), 

water quality decline caused by hydrilla, Hydrilla verticillata (Langeland 1996), and 

mudflat conversion by the smooth cord grass, Spartina alterniflora (Daehler and Strong 

1996), there are unknown numbers (likely thousands) of nonnative species with 

undocumented ecological and economic impacts. 

Basic information on species presence is necessary for ecosystem management. A 

comprehensive list of nonnative species distribution is the first step to understanding 

invasions, assessing impacts, and developing effective management actions. Several 

estuaries, bays and other protected coastal habitats of the northeast Pacific have been the 

subject of rapid assessment surveys (Cohen and Carlton 1995, Cohen et al. 1998, Mills et 

al. 2000 and Cohen et. al. 2001). Studies of ANS and ballast water release on the West 

Coast of North America have focused on ports in higher salinity estuaries and bays such 

as San Francisco Bay and Coos Bay. Freshwater-dominated estuaries and large river 

systems have received little attention. Discharge of ballast water into marine and aquatic 

systems has become a significant pathway for ANS introductions worldwide as a result of 

a substantial increase in the speed and volume of global trade over the past century 

 1

 Recent estimates place the cost of the introduction of Driessna polymorpha between $750 million and

$1 billion from 1989 and 2000 (Carlton 2001); state and federal funding for understanding impacts and 

eradicating Spartina alterniflora in the Pacific Northwest total over $4.5 million in the past 5 years; $1

million of federal funding went to Eriocheir sinensis control and research efforts in California in 2000-

2001; and control and monitoring of Caulerpa taxifolia in southern California cost $2.33 million. 

LCRANS page 1
(Cohen & Carlton 1995, Cohen 1998). Despite the considerable volume of shipping 

received by the five major freshwater and brackish ports on the lower Columbia River 

(LCR), it has never been surveyed explicitly for nonnative species. 

The United States Congress remedied this disparity in 1996 when they re-authorized the 

Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990, renamed the 

National Invasive Species Act (NISA). The authors of NISA specifically identified the

need to conduct an ecological survey of ANS in the Columbia River and authorized 

funding for this purpose. In the fall of 2001, the Lower Columbia River Aquatic 

Nonindigenous Species Survey (LCRANS) was initiated. 

LCRANS was undertaken to provide comprehensive information about the ANS present 

in the lower Columbia River. The results of this investigation will serve as a baseline for 

evaluating the rate of species introductions to the river and the efficacy of ballast water 

management regulations, and contribute important new information to ongoing regional 

ANS studies. In addition, the data may be useful for determining where the lower 

Columbia River is vulnerable to invasion and for evaluating effects of introductions on 

important ecological processes. 

The project was implemented in consultation with the LCRANS Technical Advisory 

Committee (TAC). The TAC consisted of local, regional, and national experts on 

biological invasions of aquatic systems, taxonomy, and regional resource management 

(see Appendix A for a complete list of TAC participants). The role of the TAC was not 

supervisory; rather the TAC reviewed, evaluated, and assisted LCRANS in achieving the 

following goals: 

• Develop a database for relevant information including timeframe of introduction, 

native and source regions of introduced species, modes of introduction, etc. 

• Review existing literature on ANS in the lower Columbia River. 

• Perform field surveys for ANS to complete and/or extend existing records –i.e. 

focusing on habitats and taxa not well represented in literature. 

• Design and implement replicable monitoring protocols for detecting new or 

expanding invasions. 

• Complete a written report including at minimum 1) an examination of the 

attributes and patterns of invasions of ANS in the LCR, and 2) a discussion of the 

effectiveness of ballast water management in abating ANS invasions in LCR. 

LCRANS page 2
Structure and Scope 

The objective of the LCRANS was to provide a comprehensive survey and analysis of all 

ANS present in the lower Columbia River - the tidally influenced 234-kilometer reach 

from Bonneville Dam to the Pacific Ocean, and the tidal portions of the major tributaries. 

This geographic area encompassed brackish and freshwater marshes, low salinity 

mudflats, polyhaline beaches, rocky shorelines, protected embayments, large river 

habitats, tidally influenced agricultural drainages, and urban sloughs. Due to the size and 

diversity of habitats the taxonomic scope of the LCRANS project was limited to freeliving macrophytes and animals. The project included three components: 

• A literature review of Columbia River ANS, 

• Field surveys to characterize the ANS present 

• A comprehensive analysis and summary of the results of the previous 

components. 

The field survey focused on species and habitats that were not well studied previously. 

For example, nonnative fish were recorded when captured in the course of sampling but 

were not specifically targeted during the field surveys. Much of the information in this 

report about nonnative fishes comes from the initial literature review that, unlike many of 

the invertebrate taxa, have been well studied.2

 

This report summarizes the work performed by the LCRANS team between October 

2000 and July 2004. Some sections reference previously released LCRANS reports. 

These reports are available upon request from the corresponding author or in Adobe PDF 

format from the website http://www.clr.pdx.edu under the link “LCRANS.” In order to 

further understand the ANS present in the lower Columbia River in a regional context, 

this report also describes the timeframe, source, vector, distribution, and impacts of 

invasion where possible. In the Conclusion, we discuss our major findings and their 

implications for regional ANS management, and identify data gaps and further research 

needs. 

 2

 There are several types of fish such as gobies and blennies that have been documented as introduced

unintentionally and are associated with habitats (such as rocky cervices) that are not typically targeted 

during routine fish sampling. These habitats may need to be specifically targeted in future ANS surveys 

(Andy Cohen, personal communication). 

LCRANS page 3
Chapter 2: The Lower Columbia River

The Columbia River is the largest river in the Pacific Northwest and the second largest in 

the United States (in terms of volume discharged). Its drainage basin covers 671,000 km2

in seven states and one Canadian province. Tidal influence of the Pacific Ocean is 

evident 234 km upriver to Bonneville Dam, the lowest of many impoundments on the 

river (Figure 1). The tidal influence also extends 207 km from the Pacific Ocean to 

Willamette Falls on the Willamette River, the largest tributary entering the lower river. 

The lower Columbia, from Bonneville dam to the mouth, drains approximately 46,600 

km2

. Although it represents only seven percent of the entire Columbia Basin, it is the 

most developed and urbanized portion of the watershed. 

Figure 1. The LCRANS study area – the tidally influenced portions of the lower Columbia and 

Willamette Rivers (map created by StreamNet) 

The Lower Columbia River Basin 

For thousands of years the Columbia River has been central to the existence and cultures 

of numerous Native American tribes. Lewis and Clark’s exploration of the Columbia 

LCRANS page 4
River in the early 1800s ushered in two centuries of transformation. In 1825, the British 

Hudson's Bay Company established a post at Fort Vancouver. With the arrival of the 

first European American settlers in the 1840s, who reached the lower Columbia and 

Willamette river valleys via the Oregon Trail, the shape and character of Columbia River 

began to change. Like many other bays and estuaries along the West Coast, the lower 

Columbia River became a busy port, with ships arriving daily bearing supplies and 

immigrants, and leaving with timber, furs and fish. Since then, the population of the 

lower Columbia River basin has continued to grow, accompanied by increased demands 

on the river. 

The lower Columbia River delineates the boundary between Oregon and Washington. 

Three major tributaries enter the Columbia River downstream of Bonneville Dam; the 

Willamette River on the Oregon side, and the Lewis and Cowlitz rivers from

Washington. There are five major ports along the lower Columbia River: Astoria, 

Longview/Kelso, Kalama, Vancouver, and Portland. In 1998, the US Department of 

Commerce reported that these five deep-water ports support a shipping industry 

responsible for transporting 30 million tons of foreign trade worth $13 billion each year 

(LCREP 1999). 

According to the Lower Columbia River Estuary Project (LCREP 1999) “historical 

evidence indicates that since 1870, more than half of estuarine wetlands have been lost as 

a result of diking, draining, filling, dredging, and flow regulation.” (Figure 2). In 1932, 

construction began on the first of many dams that altered the flow regime of the 

Columbia. In 1938, Bonneville Dam was completed. Located 233 kilometers from the 

mouth, Bonneville Dam marked the new upper boundary of tidal influence on the river. 

By the mid 1970s, 18 dams had been erected on the main stem of the Columbia and its 

main tributary, the Snake River. Today, the river supports numerous commercial and 

recreational activities including fishing, hydroelectric power generation, irrigation, 

aquaculture, shipping, and boating. 

LCRANS page 5
From the mouth to Skamokawa, WA (~ river km 56) the lower Columbia River is a 

coastal plain estuary3

. Sand deposition in the middle reach of the estuary has formed vast 

areas of sand flats and shoals. Dredge disposal has built up some of these areas into 

islands. There are four large, shallow embayments in the estuary (Grays, Baker, Youngs 

and Cathlamet bays) (Holton 1984). Upstream of Skamokawa, from Puget Island to 

Longview, WA and the confluence of the Cowlitz River, the Columbia is primarily a 

single channel bordered by steep valley walls (Holton 1984). Further upstream, from

Longview to the start of the Columbia River Gorge below Bonneville Dam, the river 

valley widens into a low-elevation flood plain. 

The volume of water discharged by the Columbia River varies seasonally according to 

runoff, snowmelt, and hydropower demands. Mean annual discharge is estimated to be 

7,500 m3/s, but may range from lows of 2,000-3,000 m3/s to highs of 15,000 m3/s 

(Hamilton 1990; Prahl et al. 1998; NOAA 1998; USACE 1999). Naturally occurring 

maximum flows on the river occur in May, June and July as a result of snowmelt in the 

headwater regions. Minimum flows occur from September to March with periodic peaks 

due to heavy winter rains (Holton 1984). The discharge during May-June has been 

reduced by more than 50 percent since impoundment for water storage, hydropower 

generation, and irrigation diversion in the middle and upper basin4

 (Ebel et al. 1989) 

(Figure 3). 

 3

 This delineation of the estuary is a simplification. The boundaries of the Columbia River estuary can 

be viewed as fluctuating daily, seasonally, and annually. Further complicating any generalization is 

ongoing dredging for navigation, which creates a narrow, deep channel that restricts salt water penetration 

into the estuary. Simenstad et al. (1990) give a more detailed discussion of the physical and chemical 

characteristics of the Columbia River estuary. 4 There are over 250 dams and reservoirs and 150 hydroelectric projects in the Columbia River 

watershed, including 18 main-stem dams on the Columbia and Snake rivers (USACE 2001). Extensive 

development has turned the main stem of the Columbia River into a series of slow-moving reservoirs 

impounded by 11 large dams, the lowest of which is Bonneville Dam (Sherwood et al. 1990, Prahl et al. 

1998, USACE 1999). 

LCRANS page 6
Figure 2. Habitat alteration along the Columbia River estuary contrasting the shoreline position in

1868-1875 with the present shoreline shown in outline. (Source: Lower Columbia River Bi-State

Water Quality program http://www.ecotrust.org) 

Interannual variability in stream flow is strongly correlated with two recurrent climate 

phenomena, the El Niño/Southern Oscillation (ENSO) and the Pacific Decadal 

Oscillation (USGS 2003). Historically, flooding has occurred primarily during the cool 

phase of ENSO. A major exception was the devastating 1948 Vanport flood that occurred 

when ENSO was in its neutral phase. Droughts have usually occurred during the warm 

phase of ENSO. 

Figure 3. Past and present flow data for the lower Columbia River collected at the Bonneville Dam. 

(The straight line demonstrates average estimated flow of the Columbia River prior to the

LCRANS page 7
construction of dams and other impoundments. Two extreme flood events are starred. Data from the

Columbia Basin Research team at the University of Washington

http://www.cbr.washington.edu/dart/riverclimate.html with additional pre-dam data from Pruter

and Alverson (1972)).

Salinity intrusion is flow dependent but typically extends to around 50 km from the 

mouth and is largely confined to the two main channels; the southern one is the dredged 

shipping channel that extends from the mouth to Portland, OR (Hamilton 1990). Vertical 

stratification varies from fully mixed to salt wedge conditions depending on both the 

volume of flow and tidal heights (Hamilton 1990). At the river mouth the estuary is 

considered partially mixed except at extreme low flows when it can become vertically 

homogeneous at high tide (Neal 1972, Hamilton 1990). Further upstream at river 

kilometer 30 the estuary behaves as a partially mixed estuary except during high flows at 

low tide when it can become vertically stratified or completely freshwater (Neal 1972). 

Historically the free-flowing Columbia River may have supported an “average to rich 

bottom fauna in which caddis fly and chironomid larvae, mayfly nymphs and mollusks 

predominated” (Roebeck et al. 1954 in Ebel et al 1989). Aside from catch data of 

commercially important species, however, few biological records exist for the lower 

Columbia Basin that pre-date the construction of the dams (Weitkamp 1994). Today the 

main stem of the lower Columbia River is considered depauperate in species (Ebel et al 

1989). The biological integrity of the river may be further degraded by pollution, 

destruction of wetlands, and other impacts related to industrialization, navigation 

improvement, and urbanization. While many adjustments to the impoundment of a river 

happen very quickly (Petts 1984), geophysical changes may require more than 100 years 

to adjust to major alterations of flow (Sherwood and Creager 1990). The strong linkage 

between biological communities and the physical characteristics of riverine systems may 

mean that the lower Columbia River biota is still adjusting to anthropogenic changes. 

This adjustment period may have benefited ANS (Weitkamp 1994). 

The Changing Nature of Invasions 

Human beings, unlike other species, often bring their favorite food, sport, and ornamental 

species with them when they colonize new locations (Minns and Cooley 1999). This 

pattern held true for the new arrivals to the Columbia River Basin. It is ironic to note that, 

LCRANS page 8
while the early settlers rapidly took advantage of the abundance of salmon in the region 

and made it the basis of a multi-mullion dollar industry, they soon “tired” of its pink flesh 

and yearned for the game fishes of their childhoods (Lampman 1946). Today, the region 

faces the rapid decline of native salmon stocks. 

 “They could catch a salmon whenever they wanted it. They measured their cutthroat

trout, Salmo clarkii, by the bushel... [but], by Godfrey, what they really wanted was a

big mess of catfish.” (Lampman 1946)

In the late 1800s, the United States Fish Commission (the precursor to the US Fish and 

Wildlife Service) became active in the transport and stocking of Atlantic/Eastern fish 

species on the West Coast to “increase the quality and variety of food and game fishes” 

and supplement the “worthless and unpalatable fish” (Smith 1896). Today, more than 20 

species of non-native, popular, game fish have been successfully introduced to the lower 

Willamette and Columbia rivers. 

One early fish introduction to the lower Columbia River Basin was the carp, Cyprinus 

carpio (Smith 1896, Lampman 1946). Lauded as a European delicacy as easy to raise as 

“pigs in your back yard” – the first shipments of carp arrived in the Willamette Valley in 

1879 and 1880. A great number of the carp thrived and reproduced in the pond of 

Captain John Harlow and, with the arrival of a vigorous spring freshet that swelled the 

waters of the Sandy River and freed the fish, they made their way into the lower 

Columbia River system in May 1881 (Lampman 1946). The US Fisheries Commission 

supplied additional shipments of carp to the Pacific Northwest from stock raised in 

California (Smith 1896) and by 1892 the populations of carp had grown so vast and 

become such a nuisance that the Oregonian newspaper reported that fishermen were 

“offering to supply farmers with any desired quantity [for use as fertilizer] at $5 a ton”

(Lampman 1946). 

American shad, Alosa sapidissima, were released in California in 1871. They rapidly 

dispersed along the Pacific Coast and were caught in the Columbia River as early as 1876 

(Smith 1896), ten years prior to the intentional stocking of shad fry in the Columbia 

Basin. Recently, measures were enacted by the National Marine Fisheries Service 

(NMFS) to reduce American shad populations in the Columbia River because they are 

believed to prey on, and compete with, juvenile salmon (Rishi Sharma, personal 

LCRANS page 9
communication 2002; NMFS 1995). American shad appear to have benefited from the 

construction of dams and impoundments that threaten many native fish (Weitkamp 1994). 

In 1914, the Oregon Fish and Game Commission granted permission to a private 

individual to introduce bullfrogs, Rana catesbeiana, into the mid-Columbia River basin 

below John Day (Lampman 1946). In 1924 or 1925 bullfrogs resulting from the above 

planting were shipped to Portland for further distribution (Lampman 1946). Today, 

mature bullfrogs are responsible for significant levels of predation on native aquatic 

species, particularly the Western pond turtle and the spotted frog (Crayon 2002). 

While many of the earliest non-native species introductions to the lower Columbia River 

were the result of intentional plantings, more recent arrivals appear to be the result of

unintentional introductions5

. It has been hypothesized that the physical and biological 

changes to the lower Columbia River promote the establishment of new ANS (Cordell et

al 1992, Weitkamp 1994). 

Three of the most recent ANS that have become established in the lower Columbia River 

the New Zealand mudsnail, Potamopyrgus antipodarum, a Siberian freshwater prawn, 

Exopalaemon modestus, and an Asian calanoid copepod, Pseudodiaptomus inopinus, 

differ from earlier invaders in that they are invertebrates with little or no food or 

recreational value. As such, none of these species were likely to have been intentionally 

introduced and no clear documentation of the dates and vectors of introduction exists. P. 

inopinus is believed to have been introduced between 1980 and 1990 via ballast water 

released from ships arriving from Asia (Cordell et al. 1992). When first captured in 

1995, E. modestus was immediately recognized as an invasive species because there are 

no true freshwater shrimp native to the Columbia River (Emmett et al. 2002). This prawn 

may also have arrived in ballast water (Emmett et al. 2002). The arrival of P. 

 5

 This does not exclude the possibility that several species now present in the lower Columbia River 

were the result of early unintentional introductions facilitated by shipping traffic. These early wooden

sailing ships transported numerous wood boring and fouling organisms (see Carlton and Hodder 1995 for a 

discussion of wooden ships and the dispersal potential of fouling organisms), and at least one species, the 

barnacle Balanus improvisus, is thought to have arrived in the Columbia via this vector. Cohen and Carlton 

(1995) estimate that 26% of introductions into San Francisco Bay are the result of hull fouling. In addition,

throughout the 1800s many vessels carried solid ballast made up of sand or rock dredged from the nearby

shoreline, and solid ballast has been implicated in the introduction of several marine species on the West 

Coast, e.g. Cohen and Carlton (1995) link 3% of invasions into San Francisco Bay to this vector. 

LCRANS page 10
antipodarum6

, was initially misidentified as the native snail Fluminicola virens in 

benthic surveys. When its abundance increased significantly it was correctly identified as 

an invasive species (Rod Litton personal communication). It is not known how this snail 

arrived in the lower Columbia River, but the lower Columbia population has the same

genotype as those in the Snake River and other western aquatic systems (Mark Dybdahl 

personal communication). 

Introductions 

Part of the global trend of increasing rates of introductions (see Ruiz et al. 2001, Cohen 

2002) may be the result of increasing awareness of, and efforts to find and report, 

introductions, particularly among the lesser-studied taxa. The trend may also reflect 

increasing opportunities for, and success of, introductions. For example the increasing 

speed and geographic range of global trade may facilitate the survival of species being

transported (intentionally or unintentionally) as well as the volume and variety of 

potential colonists. It has yet to be determined whether changes in vector management 

(such as the US ballast water guidelines for international shipping) have had an effect on 

the rate of introductions. 

While management regulations aimed at reducing the threat of ANS invasions in the 

United States have improved, the Pacific Northwest is nevertheless an at-risk region for 

further introductions. Many long-established pathways and vectors are unregulated or 

remain open due to a lack of enforcement of existing rules. Also, increased efficiency of 

trade and transportation, new trade opportunities, and new trade dimensions (e.g. internet 

trade) may have opened new pathways for ANS introduction. As the region experiences 

ecological alterations from global climate change, increased use of natural resources such 

as water and timber, and urbanization, modifications in the aquatic biological 

communities are likely. Effects of these changes on ANS introductions in the region are 

unknown but probably significant. 

 6

 Recorded in the benthic sampling reports of the Clatsop Economic Development Council’s salmon net

pen operation in Youngs Bay (See Litton 2000). 

LCRANS page 11
Vectors 

A vector is the vehicle or activity by which a nonnative species is transported 

(intentionally or unintentionally) and introduced to a new habitat. A fundamental 

understanding of the diversity and patterns of vectors operating in a region is essential to 

reducing new introductions. 

There may be a wide range of vectors operating at many spatial scales (i.e., between 

watersheds, estuaries, oceans, etc.) that impact a given system and result in substantial 

transfer of biological material. Tens of thousands of species are in transit globally on a 

daily basis (Carlton 2001). Some introductions may be the result of numerous vectors 

while others may be limited to one specific mechanism or action. The success of some

vectors may be limited by environmental factors like climate or seasonality. The wide 

diversity of potential vectors makes them a complex management issue, and identifying 

them is an essential step in managing invasions. It is important to note that the vectors 

listed for each species should be considered merely best estimates of the means of 

dispersal. For many species the precise vectors of dispersal are unknown. Facing a lack 

of unequivocal evidence regarding which species came in via which vector, the vectors 

assigned to each species represent “possible” vectors based primarily on life history 

characteristics of species. In the following section we detail several categories of vectors 

that may play a significant role in the introduction of aquatic nonindigenous species into 

the lower Columbia River.

Commercial Shipping and Maritime Vessels 

The introduction of nonnative organisms into the lower Columbia River by sailing 

vessels has been possible since the European discovery of the river by Capt. Robert Gray 

in 1792 - the first known arrival of a foreign sailing ship, but the imposing bar at the 

mouth of the Columbia River deterred numerous large vessels from entering the river. In 

1875, however, the U.S. Army Corps of Engineers began construction of a jetty that, 

along with dredging, turned the lower Columbia River into a major port system. 

In the early 1800s sailing ships entering the lower river arrived bearing supplies and 

immigrants and leaving with timber, furs, and fish. These ships may have introduced 

new species in the form of fouling and wood boring invertebrate and plants. Other 

LCRANS page 12
organisms may have been introduced from anchor chains, sea chests, solid ballast, and 

later, water ballast. With the advent of metal-hulled ships wood boring aquatic 

invertebrates were no longer transported on the hulls of commercial vessels. The 

introduction of anti-fouling paint and other hull-coating efforts has further reduced hullfouling communities but the contribution of hull-fouling communities to nonnative 

species introductions is not well known.7

Although numerous aspects of commercial shipping have been implicated in the 

introduction of ANS, ballast water, because of its sheer volume, remains the primary 

method by which ANS are believed to be transported globally (Carlton 2001)8

. . As ships 

continue to get bigger and faster the total volume of ballast transported will continue to 

increase as travel times decrease, thus increasing the probability that potential invaders 

will survive their journey. 

In addition to trans-oceanic ballast transport, transport of organisms in ballast water from

domestic, coastal ports is also a threat. Ships in-ballast from heavily invaded locations,

such as San Francisco Bay, may spread nonnative species along the West Coast. These 

introductions may have a high probability of establishment because transit times are short 

and they have already been challenged by transport in ballast tanks and local factors such 

as climate and competition. 

The commercial shipping industry is an important component of the Oregon economy. 

Exports from Oregon to Asian-Pacific markets alone amounted to $5.1 billion in 2001

(Oregon Bluebook Website 2004). Major exports include wheat and cereal, vehicles, soda 

ash and pot ash, (Oregon Economic and Community Development Department 2004, 

Port of Portland 2004). The Portland metro region is the leader in export sales for the 

 7

 On January 1, 2003 the International Convention Convention on the Control of Harmful Anti-Fouling

Systems went into effect prohibiting the use of harmful organo-tins (which act as biocides and over time 

leach into surrounding water) in anti-fouling paints used on ships. It also established a mechanism to 

prevent the future use of other harmful substances and pollutants in anti-fouling systems. By January 1,

2008 all organo-tin anti-fouling compounds must be removed from vessels and platforms or coated with an

approved sealant to prevent further leaching. (see http://www.imo.org for more information). 8

 Detailed investigation throughout the US has shown that ballast water transfer has acted as a major 

vector of ANS but, by comparison, much less research has been conducted on ships’ hulls and their 

potential to act as vectors of ANS in coastal waterways. On going research at SERC and elsewhere is

beginning to suggest that the threat of ANS dispersal posed by ships hulls could be greater than previously

attributed. 

LCRANS page 13
state, and ranks 11th of 253 in sales for U.S. metropolitan regions (U.S. Department of 

Commerce 2001). In 2000, the shipping industry produced a total earnings and 

consumption impact in Oregon of about $1.7 billion (Port of Portland 2004). 

A sustainable economy requires effective and efficient management of pathways of 

invasive species introduction that are associated with shipping. To protect Oregon water 

resources from the risk of ballast water-related introductions the legislature enacted SB

895 during the 2001 session., revising it with HB 3620 in 2003. The bills regulate ballast 

water discharge into Oregon waters, prohibiting all transoceanic and coastal vessels from

discharging unexchanged ballast water with a few exceptions. Oregon law allows 

discharges of unexchanged ballast water from vessels traveling within defined common 

waters. Common waters are defined as waters between the parallel 40 degrees north 

latitude and the parallel 50 degrees north latitude (ORS 783.630). Currently, Oregon law 

only allows the discharge of ballast water treated in a manner approved of by the U.S. 

Coast Guard, which creates potential problems for vessels with Washington-approved 

treatment technology that visit both Washington and Oregon ports on the Columbia 

River. Ballast water regulatory changes have occurred at international, federal, and 

regional levels and necessitate changes in Oregon regulations to ensure compatibility

with new federal regulations, proposed regulations in California, and existing 

Washington regulations. 

Vessels entering the Columbia River discharge ballast water in three locations (Monaca

Noble personal communication). Some might dump a portion of their ballast while at 

anchorage outside of Astoria, Oregon to adjust their draft before coming upriver. This 

anchorage area runs approximately three km alongside the main shipping channel. 

Vessels sometimes dump ballast while traveling up the lower river to port, again to adjust 

their draft as necessary. The majority of vessels, however, appear to dump their ballast 

while in port (Monaca Noble personal communication). Ballast water release sites likely 

differ by both vessel type and draft requirements. Ballast water uptake for vessels off

loading cargo at ports along the Columbia River likely mirrors this pattern in reverse. 

LCRANS page 14
Fishery Enhancement 

Intentional legal and illegal introductions of nonnative species to enhance local fishing 

opportunities have occurred in the lower Columbia River for nearly 150 years. In 

addition, several fishery enhancement actions may have led to unintentional species 

introductions in the region. The late 1800s and early 1900s were characterized by many 

intentional plantings by the USFC, local fishery managers, and private citizens to 

improve commercial, recreational and sustenance fishing in the region (see Lampman 

1946). Legal and illegal releases of sport fish into public and private ponds (and their 

subsequent escape) still occur, but the state wildlife agencies are becoming more 

reluctant to stock nonnative species in the region (Dailey 2003). Fish stocking activities 

in the middle and upper Columbia River also may have contributed species to the system

that subsequently spread down-stream. 

Mariculture, especially of oysters, is associated with numerous detrimental ANS 

introductions on the West Coast9

 (Cohen and Carlton 1995). However, there are no 

records of shellfish mariculture in the lower Columbia River. The low salinity of the

estuary is unsuitable for most commercially desirable shellfish, with the exception of the 

soft-shell clam Mya arenaria. This species rapidly spread up the West Coast from San 

Francisco Bay (1874) to Puget Sound (by 1889). The arrival of M. arenaria to the lower 

Columbia may have been the result of intentional introduction or it may have spread 

unintentionally in hull fouling communities (see Cohen and Carlton 1995). 

Other fishery enhancement activities associated with ANS introductions include 

freshwater aquaculture and hatchery stocking both on the lower river and upstream of the 

Bonneville Dam. There are no aquaculture activities on the lower Columbia River that 

involve nonnative species. 

Fishing and Recreational Water Use 

Recreational anglers and other water users may unintentionally transport ANS (primarily 

aquatic weeds, snails and other small invertebrate species) as they move from watershed 

to watershed. Some organisms may move as “hitchhikers”, in damp gear or boat wells, 

 9

 It has been proposed that the arrival of the Asian clam Corbicula fluminea may have been the result of

an intentional introduction to establish a food source in the Columbia River but McMahon (1982) argues

that this species spread naturally down the coast from Vancouver Island. 

LCRANS page 15
others may be transported as fouling organisms on boat hulls or as weeds trapped in boat 

propellers. The spread of zebra mussel, Driessenia polymorpha, throughout much of the 

United States has been attributed to movement by recreational boaters, etc. Although the 

practice of dumping left-over live bait has not been implicated in ANS introductions in 

the lower Columbia River, it is a potential vector for ANS introductions. The bait itself 

may be an ANS, as could be its packing material or other associated “hitchhiking” 

organisms (see live aquatics industry below). The risk of bait as ANS may increase with 

the availability of exotic bait species available for purchase on the internet (e.g. the 

Vietnamese “nuclear” worm)

10. 

Live Aquatics Industry 

The commercial transport of live aquatic species (for aquaculture, mariculture, bait, 

aquaria trade, water gardens, fisheries, scientific supply, etc.) is a vector for both 

intentional and accidental introductions of aquatic organisms. Plant and animal shipments 

may also include “hitchhikers”, species that are accidentally included with the shipment 

as parasites or pathogens and in shipping water and packaging (Olson and Linen 1997). 

Organisms in the live aquatics industry have the potential to be dispersed across broad 

geographical areas and thus can be released or escape to many different habitats 

(Chapman et al. 2003). In spite of this risk, the live aquatics industry (especially trade in 

live seafood) receives less attention than other activities that introduce nonindigenous 

species, such as ballast water (Chapman et al 2003). 

Ornamentals – the Nursery and Aquarium Trades 

Within the live aquatics trade ornamental species, defined here as those species sold for 

use in ponds and aquariums, pose additional risks. Numerous nonnative aquatic plants, 

fish, and aquatic invertebrates are offered by nurseries and aquarium stores for use in 

indoor and outdoor displays. Intentional introductions into the wild may be the result of 

releases by individuals to “enhance” a natural area, to develop a harvestable population 

for resale, to humanely dispose of/or “free” species, or to conveniently dispose of 

unwanted organisms. According to the Southwest Florida Watershed Council, aquarium

 10 The 2004 Oregon Fishing Regulations ban the import and transport of live bait fish 1) It is unlawful

to transport live (fish) bait between bodies of water, 2) Live fish may not be used or held for use as bait,

except live nongame fish may be used in the ocean, bays and tidewaters when taken from the waterbody in 

which they will be used. http://www.dfw.state.or.us/ODFWhtml/Regulations/2004_fishregs.pdf

LCRANS page 16
dumping is the leading cause of ANS introductions into the state of Florida. While many 

ornamental species may be unable to overwinter in the lower Columbia River (such as

fish in the family Characidae – including piranhas – which have been repeatedly released 

into the system, see Farr and Ward 1993) there are several established species that are the 

result of intentional releases. These include popular aquarium and pond species such as 

oriental weatherfish Misgurnus anguillacaudatus, and goldfish Carassius auratus, 

aquatic plants like Cabomba caroliniana and Egeria densa, and the Chinese mystery 

snail Cipangopaludina chinensis malleatus. Unintentional introductions also result from

flooding or other escapes from outdoor ponds, failure of commercial rearing operations, 

or improper disposal of species (especially via flow-through drainage system sometimes 

found in research labs, hatcheries, etc.). One examples of an accidental introductions into 

the lower Columbia River is the escape of nutria, Myocaster coypus from a fur farm in

Tillamook, Oregon during a flood (ODFW 2001). 

Biological Control 

There is little information on early efforts at biological control but the practice likely 

originated with the observation that predation by some animals and/or insects led to the 

reduction of unwanted species. Certainly the domestication of small felines by the 

Egyptians to reduce the presence of small rodents is such an example. By 900 AD the 

Chinese had begun successfully introducing predatory ants into their citrus groves to 

protect against worm-infested oranges. Official attempts at biological control in North 

American aquatic systems range from the failed introduction of muskellunge, Esox 

masquinongy, into a drinking water reservoir in San Francisco in the 1880s to rid the lake 

of introduced carp, Cyprinus carpio (which were later successfully removed after the 

introduction of sea lions, Smith 1896), to the release of nutria in Louisiana in the late 

1930s by state and federal agencies to control unwanted nonnative aquatic plants such as 

water hyacinth, Eichhornia crassipes, and alligator weed, Alternanthera philoxeroides

(USGS 2000). 

Grass carp, Ctenopharygodon idella, and mosquito fish, Gambusia affinis, are still in use 

as aquatic biological control organisms and are found throughout the lower Columbia 

River. Purple loosestrife, Lythrum salicari, is currently the target of a biological control 

LCRANS page 17
in the lower Columbia using insects (see http://www.oda.state.or.us for more information 

on this project). 

Pathways 

A pathway is the geographic pattern of an invasion. Some pathways may be more 

successful than others (Chapman 2000). Due to climate compatibility and life history 

ranges of potential invaders the temperate shorelines of continents are more likely to be

invaded by species from less temperate climates. Pathway analysis may also reflect longestablished trade routes or patterns of repeated, high-volume inoculations from particular 

locations. Such information could be vital to making management decisions about which 

vectors presented the greatest risks to a region. For example, if introduced species 

populations are dominated by species transported by a particular vector from a particular 

location, management actions could be taken to target that pathway rather than the entire 

vector. 

The lower Columbia River is part of an established trade route between eastern Asia and 

western North America. Commercial shipping traffic routinely arrives at the five major 

deep-water ports in the lower river from destinations such as Korea, China, Taiwan and 

Japan. This pathway encompasses the high-risk transport of species from less temperate 

climates to the temperate western coast of North America. 

Occasional events may increase risk of transportation of nonindigenous species. One 

example that is relevant to the lower Columbia River is the observance of the 

bicentennial of the Lewis and Clark Expedition. As part of the observance boaters are 

encouraged and expected to re-create the journey of Lewis and Clark from the Midwest 

to the Pacific Ocean. This activity is a potential conduit for transporting zebra mussels, 

Dreissena polymorpha, and other ANS from infested waters to the Columbia. More

frequently occurring events such as conventions and fairs where live aquatics may be 

displayed, sold or bartered, etc. may also be events that sporadically increase the risk of

introductions. 

LCRANS page 18
Chapter 3: Literature Review 

Methods 

Publications, reports, and collection records referring to projects conducted on the lower 

Columbia River were reviewed to compile a list of nonnative species reported in the 

study area and to identify gaps in the taxa and/or habitats studied. The goals of the 

literature review were to: 1) compile a list of non-native species already reported from the 

Columbia River, 2) identify taxa that have been poorly studied or represented in previous 

studies, and 3) identify areas of potential ANS hot-spots such as habitats associated with 

previously reported ANS and cryptogenic species, as well as habitats that have been 

under studied. All results were entered into a database. 

Due to a dearth of information on ANS in the lower Columbia River the literature review 

was expanded to include all species collections in the study area. The expansion of the 

review encompassed many reports that do not discern between native and nonnative 

species. The compiled species list was distributed to the TAC and other taxonomic 

experts for review. 

Personal contacts and electronic database searches were conducted for information on 

ANS in the lower Columbia. Two electronic databases were searched for journal articles: 

BIOSIS Previews and ASFA (Aquatic Science and Fisheries Abstracts). The online 

catalog ORBIS (Orbis Cascade Alliance) allowed a search of participating Pacific 

Northwest academic libraries including but not limited to Portland State University, 

Oregon State University and the University of Washington. In addition the libraries and 

references published by the following organizations were searched: Columbia River 

Estuary Studies Task Force (CREST), Lower Columbia River Estuary Project (LCREP), 

Portland General Electric, National Marine Fisheries Service (NMFS), Army Corps of 

Engineers, and the Oregon Department of Fish and Wildlife (ODFW). Informal 

interviews of natural resource personnel were conducted at many of the above 

organizations. Other reports were retrieved from a variety of sources using the 

Interlibrary Loan Program at Portland State University. 

LCRANS page 19
Results 

The complete results of the LCRANS Literature Review were published previously and 

are available at the Center for Lakes and Reservoirs website (http://clr/pdx/edu). Copies 

of the LCRANS database are available upon request from the authors. 

Database 

The format of the database was developed in coordination with SERC. The LCRANS 

database includes all of the relevant categories proposed by SERC including: timeframe

of introductions, native and source regions, modes of introduction, taxonomy and 

synonymy, etc. The LCRANS database differs from the SERC database in two major 

ways - the database includes fields for information collected on native species in the 

lower Columbia River and several fields that appear in the SERC database were omitted 

or renamed because they were not applicable to the freshwater ANS present in the 

LCRANS survey (e.g. biogeographic ocean provinces). All data entered into the 

database is cross-referenced with a full list of bibliographic sources. 

Literature Review 

With the exception of fishes, there is little historical information available on the flora 

and fauna of the Columbia River. Many of the invertebrate taxa, such as oligochaetes 

and epibenthic meiofauna were poorly studied. Information on species present in the 

literature was complicated by potential misidentifications (Leslie Harris personal 

communication). Such errors can result in false conclusions on their origins (e.g., 

Carlton 1979, Rotramel 1972, Chapman 1988, Chapman and Carlton 1991, 1994). The 

nonindigenous status of a species occurring in the Columbia River or elsewhere in 

northeast Pacific may not be apparent until the organism is discovered and described as 

indigenous in its native habitat, or until the synonymies of the local species with 

populations in other parts of the world are resolved (a time consuming undertaking that is 

outside the scope of most parochial biological surveys)11. 

 11 Published information associated with a species is only accessible under the scientific name of that 

species. The names of species change as errors in taxonomy are corrected. Few species that have been

recognized for long periods or are widely distributed have been static in their nomenclature; most species 

bear many epithets. Widely distributed species are often misidentified as new species when they are found 

far away from the localities where they were originally described. Tracking the synonymies and name

changes is complicated but necessary to allow for searches for information on a species under its previous

LCRANS page 20
Three projects have comprehensively surveyed the fauna of the lower Columbia River. 

In 1984 the results of the Columbia River Estuary Data Development Program

(CREDDP) were published to augment the Atlas of Physical and Biological 

Characteristics of the Columbia River Estuary. In the early 1990s the Bi-State Water 

Quality Program published its findings on the state of the lower Columbia River. Lastly, 

in 1999, the Environmental Protection Agency conducted a two-year sampling effort in 

the lower Columbia River as part of its Environmental Monitoring and Assessment 

Program West Coast Project (EMAP). 

Using these three comprehensive surveys and several site-specific studies (Table 1), we 

compiled an inventory of the flora and fauna of the lower Columbia River. Many of the 

previous studies were limited in taxonomic and geographic scope. 

 names. Each error in the taxonomy of a species prevents access to information under the correct names. 

Without continuous revisions, local taxonomic literature does not include information on new discoveries 

elsewhere in the world. The taxonomy of ANS therefore requires continuous reevaluation, based on the

world taxonomic developments. 

LCRANS page 21
Table 1. Principal biological surveys of the lower Columbia River consulted by the literature review. 

Sampling 

Period Organisms Targeted Sites 

Agency or Program 

(Published References) 

1962-1963 Fish Lower Willamette (Hutchinson and Aney 1964) 

1963-1964 Fish freshwater tributaries of the 

lower Columbia

(Reimers 1964, Reimers and Bond 1967) 

1963-65 fish, benthic invertebrates,

zooplankton 

sites on the mainstem to

Harrington Point 

(Osterberg 165, Haertel & Osterberg 1967, Haertel 1970) 

1971-1972 Zooplankton Columbia River estuary NMFS (Misitano 1974) 

1973 fish, benthic invertebrates,

zooplankton 

Lower Columbia River NMFS & USACE (McConnell et al. 1973; Durkin 1973; 

Durkin & McConnell 1973; McConnell et al. 1973; 

Misitano 1973; Sanborn 1973) 

1973-75 fish, benthic infauna Youngs Bay and tributaries OSU (Higley & Holton 1975; CREDDP 1980a,b) 

1975-1977 fish, benthic invertebrates,

plants 

Miller Sands USACE (Clairain et al. 1977) 

1975-77? fish, benthic invertebrates Estuarine beaches of Columbia 

River 

NMFS (Durkin et al. 1977) 

1975-78 Benthos Alder Creek in Youngs Bay (Montagne & Assoc. 1977, in CREDDP 1980a) 

1975-78 benthos lower estuary OSU (Higley et al. 1976; Higley & Holton 1978); 

CREDDP 1980a) 

1978-80 tidal marsh plants Columbia River estuary CREDDP (MacDonald & Winfield 1984) 

1980-81 Fish primarily in the main stem of 

the Columbia River estuary 

CREDDP, NMFS & ODFW (Bottom et al. 1984, Bottom 

and Jones 1990)

1980s Mammals lower Columbia River CREDDP (Howerton 1984) 

1978-80 benthic infauna lower Columbia River CREDDP (Holton 1984) 

1978-80 epibenthic organisms lower Columbia River CREDDP (Simenstad 1984) 

1980-81 benthic invertebrates Baker Bay near Ilwaco NMFS (Furota & Emmett 1993)

1980s benthic invertebrates Cathlamet Bay NMFS & USFWS (Emmett et al. 1986; Durkin et al. 1982) 

1987-1992 benthic invertebrates,

demersal fishes 

freshwater mainstem of the 

lower Columbia River 

NMFS (McCabe and Hinton 1990, McCabe et al. 1990, 

McCabe and Hinton 1993, McCabe et al. 1993, McCabe et 

al. 1997) 

1990-92 benthic invertebrates mouth to Bonneville Dam BSWQP (Ellis & DeGasperi 1994) 

1991-1994 fish, benthic invertebrates Rice Island, Miller Sands NMFS (Hinton et al. 1992a, Hinton et al. 1992b, McCabe 

et al. 1993, McCabe et al. 1996) 

1990-1992 Fish lower Willamette River ODFW (Ward and Nigro 1992) 

1995 fish, benthic invertebrates Trestle Bay USACE (Hinton & Emmett 2000) 

1998 freshwater bryozoans Willamette River (Marsh and Wood 2002) 

1999-2000 benthic invertebrates mouth to Bonneville Dam WEMAP12, WDE & ODEQ 

2001-2002 fish, benthic invertebrates lower Willamette River ODFW, City of Portland (North et al. 2002) 

2002 Plants lower Columbia River LCREP 

2003 Plants Astoria shoreline CREST (CREST 2003) 

 12 Portions of the 1999-2000 WEMAP Survey data from the did not become available until the literature 

review was completed and are not reflected in the previous LCRANS Literature Review release. 

LCRANS page 22
The literature review revealed uneven coverage of taxa. Nonnative fishes and aquatic 

plants (submersed, floating, emergent and marsh) were the most abundant introduced 

taxa of the lower Columbia (Table 2). Native and non-native fishes of the lower 

Columbia River and its tributaries have been well described (Hutchinson and Aney 1964, 

Reimers and Bond 1967, McConnell et al. 1973, Bottom et al. 1984, Ward and Nigro 

1992, North et al. 2002, but there was little information on nonnative and cryptogenic 

invertebrates. These species were poorly-studied and rarely identified as introduced or

potentially introduced species. A complete species list is available in Appendix B. 

Intentionally and unintentionally introduced species are present in the lower Columbia 

River. The non-native fishes were dominated by intentionally introduced species. The 

invertebrates were considered primarily unintentional introductions. 

Table 2. Summary of nonindigenous and cryptogenic species compiled during the literature 

review,listed by major taxonomic category. 

Taxon Nonindigenous

Species 

Cryptogenic 

Species 

* Indicates species counts that include introductions that failed or are thought to have failed to

become established, for example: Homerus americanus has been introduced intentionally with no

known surviving populations. # May include native species that were misidentified.

Plants 23 5

Mammals 1 0

Herptiles 3 0

Fishes 36* 1

Annelids 6 37#

Amphipods 1 3

Copepods 6 12#

Decapods 4* 0

Isopods 1 1

Bivalves 2 0

Gastropods 2 0

The cryptogenic species list compiled during the literature review includes species, that 

have been identified as non-native, but for which the validity of the identifications is 

uncertain and unverifiable. This is principally suspected of species in poorly studied 

taxonomic groups (e.g., polychaete worms, aquatic insects, oligochaetes). Consulting

taxonomists concluded that many of these species were not correctly identified in the 

papers and reports surveyed. Mis-identifications could have resulted from the use of 

LCRANS page 23
inaccurate local keys, inexperienced taxonomists, or attempts to fit unrecognized non 

native species into local species keys. 

From the literature review we concluded that there are biological communities and 

habitats within the lower Columbia River that are poorly studied. Patchy habitats and 

poorly characterized areas exist in the estuary as well as further upriver. Several ANS 

such as the anthozoa, Nematostella vectensis, and Japanese eelgrass, Zostera japonica, 

have been reported from the two relatively high salinity bays at the mouth of the 

Columbia; Trestle Bay and Baker Bay (Furota and Emmett 1993, Hinton and Emmett 

2000, EMAP unpublished data) but no follow up information exists on these populations. 

Although common along the main-stem, tidal freshwater sloughs are also poorly 

characterized and many exist adjacent to major deep-water ports, features that made them

of special interest to this survey. We hypothesized that such areas may provide 

protection from strong flushing events and could therefore provide non-native aquatic 

macrophytes, insects and epibenthic invertebrates opportunities to establish. Other sites 

of interest to us had records where a variety of poorly characterized organisms, i.e. 

oligochaetes, were collected but not identified to species. 

LCRANS page 24
Chapter 4: Field Sampling 

Methods 

The 2002 and 2003 field surveys were guided by sampling plans built on prior knowledge 

and reviewed by the TAC. The literature review was integral to the development of a 

stratified and adaptive sampling plan. Limited resources and the relatively large area

required that we identify areas of interest such as locations closely associated with ballast 

water release, habitats with previously reported ANS and cryptogenic species, and areas 

that have been understudied previously. It was also deemed important to avoid 

duplication of new and ongoing projects, (i.e. the EMAP survey conducted by the EPA, 

ODEQ and WDOE); we wanted to conduct sampling complementary to these efforts. 

The 2002 survey focused on taxa and habitats that were poorly represented in the 

literature, sites that could be re-sampled at regular intervals in a long-term monitoring 

program, and/or sites that had a reliable historical record to permit evaluation of invasion 

rates. In 2003, we re-sampled those stations identified as potential long-term monitoring 

stations, and some additional new stations. Whenever appropriate, members of the TAC 

were asked to comment on the targeted sampling efforts, species identifications, and 

regional ANS information. When sampling was limited by access and weather we either 

arranged to return to those stations or attempted to sample as near to those locations as 

possible. 

The taxonomic scope of the LCRANS project was limited to free-living macrophytes and 

animals, except in unmistakable cases of disease causing organisms and parasites, which 

were noted when they were observed. Taxa that have not been well studied by previous 

investigators were the primary focus of these surveys. We did not conduct surveys of the 

fishes, which are the most studied fauna of the lower Columbia River, or the insects, 

which we could not identify to species reliably. 

Locations 

Seventy-two stations were sampled from the Bonneville Dam to the Pacific Ocean 

between April 2002 and October 2002 (Figure 4). Fifty-three sites were sampled by 

invertebrate and aquatic macrophyte experts. The remaining nineteen stations were 

LCRANS page 25
sampled specifically for nonindigenous aquatic macrophytes (although the presence of 

nonnative mollusks was also noted when apparent at these sites). In 2003, 62 stations 

were sampled (Figure 4). Invertebrate communities were sampled at 36 stations and 

plant surveys conducted at more than 30 stations between May and September. In 2003, 

phytoplankton surveys were conducted at seven stations in the lower river. Gaps in the 

spatial distribution of 2002 sampling were also addressed, including the Willamette River 

and parts of the mainstem of the lower Columbia that had not been adequately sampled in 

2002. In 2003 we devoted more sampling effort to the mainstem of the Columbia in the 

estuary, between Portland and Bonneville Dam, and on the Willamette River. In 

addition, special effort was made to sample and identify soft-bodied benthic organisms 

such as polychaete worms. A more thorough aquatic macrophyte survey was also 

conducted that noted macroinvertebrate communities associated with both native and 

nonnative aquatic plants (Figure 5). At some locations only nonnative species of aquatic 

plants were noted. 

Techniques 

The major substrates and microhabitats sampled included intertidal and subtidal mud,

sand, gravel, cobbles, rocks, banks, artificial substrates such as floats and pilings, and 

aquatic plants. Every accessible habitat at each sampling station was sampled. Sampling 

was conducted at various lengths of time at each location, depending on the number of 

habitats present; sampling usually occurred during low tide. Estuary sampling was 

scheduled to coincide with negative low tides during daylight hours to increase access to 

hard substrates. Tidal amplitudes in the freshwater reach of Columbia River above 

Longview did not affect access to substrates. A variety of sampling methods were 

employed including collection by hand, scraping substrata using a 2-mm mesh stainless 

steel mesh sieve attached to a long pole developed specifically for sampling vertical 

fouling communities, a 0.0225-m2 Petite Ponar grab sampler, 700-μm epibenthic sled, a 

250-μm mesh zooplankton net, a 80-μm mesh phytoplankton net, a plant rake, several 

types of kick and dip nets. Sampling was conducted to obtain the best qualitative 

coverage possible. Quantitative sampling protocols and precise species counts were not 

deemed necessary in order to develop a comprehensive list of species present. 

LCRANS page 26
Benthic organisms were collected by vigorously agitating mud, sand, gravel and rock 

samples in water to suspend organic material and small invertebrates. The suspensions 

were decanted through a series of mesh sieves (2-mm, 1-mm mesh, and 0.5-mm) to retain 

suspended organisms. The washing and decanting procedure was repeated until the 

majority of organisms in the samples were removed. Sub-samples were made only when 

the total volume of organisms retained on the sieves exceeded the volume of the largest 

sample containers. 

In 2003 many samples were collected specifically for oligochaete analysis by Steve Fend. 

Depending on field conditions these samples were either picked live and un-sieved or

preserved un-sieved for later sorting with 200-μm sieves. Live specimens were preserved 

by first anaesthetizing the sample in dilute alcohol for 10 minutes, then fixing by slowly 

adding a formalin-alcohol-acetic acid (FAA) solution. 

Bulky samples of aquatic plants, peat, rocks or gravel or other similarly course 

substratums, were washed on a 4-mm or 2-mm mesh sieve in a 20-liter dishpan. Large 

organisms and unique organisms were removed directly to sample containers. Smaller 

organisms were captured by decanting the wash water through 0.5-mm and 1-mm mesh 

sieves. This procedure was repeated until most of the invertebrates in the sample were 

acquired 

LCRANS page 27
Figure 4. LCRANS sampling locations 2002, 2003 

LCRANS page 28


  

 

 Sampling Locations  Phytoplankton

0 37.5 75 150 Kilometers









   





 



 







 













 



 



 Sampling Locations  Plants

0 37.5 75 150 Kilometers



























 

 





 









 





 





 



 







 Sampling Locations  Zooplankton

0 37.5 75 150 Kilometers

Figure 5. Distribution of LCRANS sample types 2002-2003 

Organisms retained on the sieves or picked out of samples were placed into plastic bags 

or jars of water from the sample location for later examination and sorting in the 

laboratory. Live samples were kept on ice and processed on the same day they were 

collected. These collection methods usually produced large numbers of undamaged 

invertebrates suitable for taxonomic identifications. 

Zooplankton and phytoplankton were collected with water column plankton hauls made 

either off a dock or from a boat with a 0.25-m diameter, 250-μm mesh plankton net 

(zooplankton) and an 80-μm mesh plankton net (phytoplankton). The net was lowered to 

the bottom, and after several minutes was slowly pulled to the surface. In the laboratory, 

each plankton sample was examined under a dissecting microscope, and representatives 

of each species were removed. If necessary for identification, diagnostic parts (e.g., fifth 

legs of copepods) were removed and examined under a compound microscope. 

LCRANS page 29
Sorting thousands of specimens collected in some of the fouling and benthic samples was 

impractical and unnecessary for the purposes of the survey. Therefore, in the final 

sorting, abundant and highly visible species were collected only during the first 40-60 

minutes and then an additional 40-60 minutes of sorting was performed under a 

stereomicroscope to collect rarer or inconspicuous species. Live sorting of the samples 

allowed identification of species that were unique in behavior or coloration, and that 

might have been overlooked in fixed samples. The large size of the benthic samples 

greatly increased the probabilities of collecting all species present. 

Classification of species 

Distinctions between nonindigenous, cryptogenic and native species were based on 

criteria for introduced species developed by Lindroth (1957), Carlton (1979), Webb 

(1985), Chapman (1988), and Chapman and Carlton (1991, 1994) (Table 3). Application 

of these criteria to each species required detailed information on their taxonomy, 

biogeography, ecology, and life histories. Therefore, taxa for which this information did 

not exist (e.g., non-commercial species, poorly known groups) were difficult to assess. 

Species were considered native when most of the criteria were not met and introduced 

when most of the criteria were met. The degree of certainty of the classification of each 

species was assessed from the number of criteria that applied, and the quality of the data 

used to assess the criteria. Satisfaction of a single criterion was rarely sufficient evidence 

that a species is introduced. Satisfaction of multiple criteria, however, was considered

definitive for the nonindigenous or native origins of species even though the criteria are 

largely subjective. Species for which evidence of these criteria was mixed or unclear 

were defined as cryptogenic (Carlton 1996). All specimens that were identified to 

species level were classified according to the native vs. nonnative criteria. Species that 

could not be identified to species were classified as cryptogenic. Application of the 

criteria relied on the quality of associated systematic, ecological, and historical data. 

Pertinent information was often lacking, and species were included in these analyses only 

when they were confidently identified. 

LCRANS page 30
LCRANS page 31

Table 3. Criteria for introduced species modified from Chapman and Carlton (1991, 1994) and Lindroth (1957), Carlton (1979)Chapman (1988). (1) Historical records of introduction. (Game, aquaculture, agriculture or otherwise intentionally introduced species are commonly recorded upon entry.)(2) Association with human mechanisms of introduction. (Species are associated with particular mechanisms of introduction by timing and location of arrival and direct association such as organisms that occur in the fouling communities on the hulls of ships or oysters or in ballast water discharged from ships, aquarium pets.)(3) The absence from fossil deposits or from Native American shell middens in regions where the species is present. (Species with hard parts, such as adiatoms, sponges, mollusks, bryozoans, echinoderms, and vertebrates leave fossil remains that can be of sufficient quality for species identifications. Thprehuman fossil deposits is evidence of native origins. Therefore, their absence in fossil assemblages of communities in where they presently occur is evrecent appearance. Fossils are not as useful for species of genera such as the bivalves Mytilus and Ennucula that are extremely difficult to distinguish by and peracaridan fossils are all but unknown.) (4) Insufficient natural dispersal mechanisms to create the entire global distribution of a species. (Many species do not have specialized adult or larval disassociations with natural dispersal mechanisms that could transport them across major geographic barriers. The occurrence on both sides of dispersal bspecies is evidence of their nonindigenous status.) (5) Appearance in regions where not found previously. (Recent appearances of conspicuous species such as the green crab and the Chinese mitten crab Pacific or a charismatic species such as the cholera bacterium, Vibrio cholerae in the southeast Pacific where they would not be overlooked previously arthey were introduced by human activities.) (6) Discontinuous or otherwise incomplete local distributions relative to those of ecologically similar endemic species. (Incomplete dispersal by the mechaintroduction, poor adaptation to the range of local conditions, and early stages of invasion within new geographic ranges create disjunct distributions that among native species.) (7) Recent spread from one or a few locations to broad geographical areas. (Introductions invariably begin in isolated areas due to the uneven occurrencmechanisms of dispersal. Thus, ballast water introductions spread from shipping ports and aquaculture introductions spread from areas where aquacultu(8) Close associations with other introduced species. (Spatial associations of introduced species result, in small part, from their common mechanisms of possibly in greater part from the patchy, aggregated distributions of introductions due to poorly understood ecological and biological factors. The fouling cfloats in San Francisco Bay are dominated by ANS that are identified by other criteria. Additionally, the specialization of some parasites and predators on species can reveal their nonindigenous origins.) (9) Restriction to new or artificial environments. (Introduced aquatic species commonly are restricted to substratums or habitats, such as cement or styrorip-rap over mudflats, and boat hulls, that were absent, uncommon or ephemeral before European settlement. A complete dependence on such artificial unlikely among native species.) (10) Conspecific with geographically isolated populations. (All recent introductions are geographically isolated from their native populations and thereforeintroduced species are conspecific with geographically isolated native populations.) (11) Non-endemic evolutionary origins apparent from membership in a non-indigenous taxonomic group. (Introduced species are often morphologically osimilar to geographically isolated taxonomic groups rather than local groups.) (12) Non-endemic evolutionary origins apparent from ecological or physiological adaptations. (Many introduced species are from climates were temperatthose in the new location or where they escape parasites or diseases. Some introduced species tolerate temperatures, for instance, that do no exist in thOther ANS are vulnerable to nonindigenous parasites, such as the green crab to the parasitic barnacle Sacculina carcini, to which the native northeast Panot vulnerable.
Transportation vectors, dates of discovery and the definition of native range relied 

heavily on available ecological and historical data and may not represent the definitive 

pattern of introduction (i.e. when it arrived, how it arrived, and where it came directly 

from), information which remains unknown for many species. When more than one 

vector was found in the literature or determined from species’ life history characteristics 

all of them were included in the results. The following vectors were assigned to each 

introduced species where appropriate. 

• Aquarium - intentional aquarium disposal by an individual into waters of the 

basin 

• Ornamental - ornamental species escape (e.g. flooding of a private pond), 

release, or improper disposal by an individual 

• Release by individual - other types of release by individuals (i.e. does not 

include aquarium or ornamental species or actions taken by state or federal 

agencies) release my be intentional or accidental (e.g. dumping of bait or bait 

packing material into water, unintentional transport of species in recreational 

gear, release of live food species for religious or humane purposes, etc. 

• Accidental - accidental introduction accompanying intentional introduction of 

a different species by a state or federal agency (does not include introductions 

associated with oyster planting;

• Escape - escape from commercial cultivation 

• Fishery enhancement - intentionally introduced for fishery or wildlife 

enhancement by an agency rather than an individual 

• Solid ballast - entrained with solid ballast used by ships in the 1800s before 

ballast water became prevalent 

• Ballast water – collected and transported in ballast water taken on to stabilize 

commercial, military and other vessels 

• Ship fouling - transported as part of the fouling community on the hulls of 

ships, anchor chains, etc.

• Gradual spread – species arrived via natural mechanisms of spread from

introduced populations outside of the lower Columbia River (i.e. transported 

by birds, wind, water, etc.) often associated with Japanese or Atlantic Oyster 

introductions in other estuaries 

• Biological control – species introduced intentionally by an agency or an

individual for biological control purposes 

LCRANS page 32
Chapter 5: Results and Discussion 

Field Survey Results 

Samples were collected from the field at the 134 sampling stations. We documented 269 

aquatic species (and 55 other distinct organisms that we were unable to identify at the 

species level and are labeled as “unknown” in the following figures) in the lower 

Columbia River. Of the 269 species identified, 54 (21%) were introduced, 92 (34%) 

were native, and 123 (45%) were cryptogenic. It is important to note that vertebrates 

were not intentionally targeted in our sampling and not all native plants (especially 

emergent and marsh species) were recorded during plant surveys. 

The introduced, native, and unknown species collected from the lower Columbia River 

were mostly invertebrates (Figure 6). There were slightly more cryptogenic 

phytoplankton than cryptogenic invertebrates. The cryptogenic phytoplankton and 

invertebrates accounted for nearly half of all the species collected. The low number of 

vertebrates collected can be attributed to sampling methods and does not reflect the actual 

number of vertebrates (especially fish) present in the lower river. In addition, these data 

do not reflect all of the native plants present (primarily emergent and marsh species) 

because those species were not recorded during plant surveys. 

Plants/Phytoplankton Invertebrates Vertebrates

0

10

20

30

40

50

60

70

80

Number of Species

Introduced

Native

Cryptogenic

Unknown

Figure 6. LCRANS field survey species collections broken down by major taxonomic group and 

origin. 

LCRANS page 33
Crustaceans were the most abundant introduced invertebrates (42%) followed by annelids 

(30%) (Figure 7). The introduced invertebrates were dominated by benthic organisms. 

Benthic invertebrates accounted for 61% of all introduced invertebrates collected and 

36% of the total number of introduced species. Fouling organisms (organisms capable of 

attaching to surfaces like stone, concrete, wood, piers, docks, and boat hulls) comprised 

23% of the introduced invertebrates. Pelagic organisms accounted for the remaining 

invertebrates. Phytoplankton

Macroalgae

Plants

Annelids

Mollusks

Crustacean

Other Invertebra

Amphibian

Mam

mals

0

10

20

30

40

50

60

70

Number of species

s

tes

Fish

s

Introduced

Native

Cryptogenic

Unknown

Figure 7. LCRANS field survey species collections broken down by minor taxonomic group and 

origin 

Although vertebrates were not specifically targeted by this effort five introduced fishes 

and one mammal were documented (Figure 7). The single introduced mammal was the 

nutria, Myocaster coypus, a semi-aquatic rodent that was seen at numerous stations along 

the Willamette River. 

Cryptogenic species numbers were dominated by phytoplankton, oligochaetes and many 

types of zooplankton (Figure 7) for which little information is available on native range. 

All of diatoms, dinoflagellates, and other phytoplankton collected were classified as 

LCRANS page 34
cryptogenic in this study. In addition, several of the species collected, such as

Gasterosteus aculeatus or Branchiura sowerbyi, are subject to changing expert opinions 

on origin. 

Eight of the 54 introduced species collected were new records for the lower Columbia 

River. One of these species, the oligochaete Eukerria saltensis, appears to be a new 

record for the West Coast. The other seven species, the oligochaetes Branchiura 

sowerbyi, Chaetogaster diaphanous, Paranais frici, and Stylodrilus heringianus, the 

purple varnish clam, Nuttallia obscurata, the Chinese mystery snail, Cipangopaludina 

chinensis malleatus, and the crustaceans Limnoithona tetraspina and Melita cf. nitida 

have been reported previously at other West Coast locations. 

Literature Review and Field Survey Results 

Combing the results from both the field surveys conducted in 2002 and 2003 with the 

results of the earlier literature review (complete literature review results available at

http://www.clr.pdx.edu/) we determined that at least 81 new organisms have been 

introduced into the lower Columbia River since the mid 1800s (Figure 8, Table 4).13 The 

majority of these species were fish (28%), aquatic plants (23%) and crustacea (15%). 

The remaining 18% was a combination of mollusks, annelids, bryozoans, cnidaria, 

amphibians, reptiles and an aquatic mammal. 

 13 Those species not collected by LCRANS in 2002 or 2003 are species collected either by WEMAP in 

the lower Columbia in 1999 and 2000 and validated by the same team of taxonomists as used by LCRANS, 

or species noted in the LCRANS literature review and confirmed by regional taxonomists or our team of

experts. 

LCRANS page 35
Phytoplankton

Macroalgae

Vascular Plants

Annelids

Mollusks

Crustaceans

Other Invertebrates

Fish

Herptiles

Mammals

0

5

10

15

20

25

LCRANS

LITERATURE REVIEW

Figure 8. Number of introduced species in various taxa in the lower Columbia River from the 

literature review and field survey. 

LCRANS page 36
Table 4. Invasion dates and mechanisms of introduction for all introduced species present in the lower Columbia River. This ta

one-time unsuccessful introductions or seasonally limited introductions such as piranha, lobster, etc. reported from the literatu

included on this list as a result of the literature review appear without bold lettering and were reviewed for inclusion on this list experts before labeling them as present in the lower Columbia River basin. 

Species Common Name Native Range

1st Western

Collection

1st LCR 

Collection V

Mechanism abbreviations: AQ = aquarium disposal, OR = ornamental species (escape, release, disposal), RI = release by individual (not considered a

species nor released by a state or federal agency), AX = accidental introduction accompanying intentional introduction, ES = escape from commercial 

or wildlife enhancement, intentional by a state or federal agency, SB = solid ballast, BW = ballast water, SF = ship fouling, GS = gradual spread from ot

outside of the river, and BC = biological control organism 

PLANTSVascular 

Cabomba caroliniana Carolina fanwort NA, SA ? Callitriche stagnalis pondwater starwort EUR-ASIA 1871, 1902 ? BCotula coronopifolia brass buttons AF 1878 ? Egeria densa elodea SA ? 1944 Iris pseudocorus yellow flag iris EUR 1860s ? Lythrum salicaria purple loosestrife EUR 1880s ? ORMyriophyllum aquaticum parrot's feather SA <1957 ? Myriophyllum spicatum Eurasian milfoil EUR, AF 1976 ? Mentha aquatica water mint EUR ? ? GSMentha aquatica x spicata peppermint EUR ? ? GLudwigia uruguayensis water primrose SA ? 1956 Nymphaea odorata fragrant water lily NA ? ? OPhalaris arundinacea reed canary grass NA ? ? Phragmites australis common reed NA ? ? Potamogeton crispus curly leaf pondweed EUR-ASIA ? 1947 RI, OSagittaria subulata awl-leaf arrowhead NA ? ? Typha angustifolia narrow-leaf cattail EUR-ASIA 1951 ? Vallisneria Americana water celery NA 1900s ? Zostera japonica Japanese eelgrass NW Pacific ? ? 

LCRANS page 37
LCRANS page 38

Table 4. cont. 

Species Common Name Native Range

1st Western

Collection

1st LCR 

Collection

M

Mechanism abbreviations: AQ = aquarium disposal, OR = ornamental species (escape, release, disposal), RI = release by individual (not considered 

species nor released by a state or federal agency), AX = accidental introduction accompanying intentional introduction, ES = escape from commercia

wildlife enhancement, intentional by a state or federal agency, SB = solid ballast, BW = ballast water, SF = ship fouling, GS = gradual spread from othe

of the river, and BC = biological control organism

INVERTEBRATES 

Bryozoa 

Fredericella indica NA ? 1999 Pectinatella magnifica NA ? 1999 

Anthozoa

Nematostella vectensis NW Atlantic 1946 1994 

Hydrozoa 

Cordylophora lacustris EUR ca 1920 1965 

Oligochaeta

Branchiura sowerbyi 

Black-Caspian 

Sea 1950 2002 

Chaetogaster diaphanous not known 2002 2003 Eukerria saltensis SA ? 2003 Paranais frici EUR 1961 2003 Stylodrilus heringianus EUR ? 2003 

Polychaeta 

Hobsonia florida NA 1940 1975 Manayunkia aesturina NA ? 1981 Manayunkia speciosa NA 1961 1999 Polydora cornuta N. Atlantic 1932 1981 Pseudopolydora kempi NW Pacific 1951 1991 Streblospio benedicti N Atlantic 1932 1999 

Gastropoda

Cipangopaludina chinesismalleatus Chinese mystery snail ASIA 1950s 2002* 
LCRANS page 39

Table 4. cont. 

Species Common Name Native Range

1st Western

Collection

1st LCR 

Collection

M

Mechanism abbreviations: AQ = aquarium disposal, OR = ornamental species (escape, release, disposal), RI = release by individual (not considered 

species nor released by a state or federal agency), AX = accidental introduction accompanying intentional introduction, ES = escape from commercia

wildlife enhancement, intentional by a state or federal agency, SB = solid ballast, BW = ballast water, SF = ship fouling, GS = gradual spread from othe

of the river, and BC = biological control organism

Potamopyrgus antipodarum New Zealand mudsnail AUS-NZ 1980s <1995 

Bivalvia 

Corbicula fluminea Asian clam ASIA 1924 1932 Mya arenaria soft-shell clam NA, EUR 1874 <1900 Nuttallia obscurata purple varnish clam ASIA 1990 2003 

Crustacea 

Balanus improvisus bay barnacle NA, EUR 1853 <1900 Acartiella sinensis ASIA 1979 1997 Limnoithona sinensis ASIA ? 1979 Limnoithona tetraspina ASIA 1993 2003 Pseudodiaptomus forbesi ASIA ? 1999 Pseudodiaptomus inopinus ASIA ? 1990 Sinocalanus doerri ASIA 1978 1999 Tachidius (Neotachidius) triangulari ASIA ? 1990s Nippoleucon hinumensis ASIA 1979 1999 Caecidotea racovitzai racovitzai EUR 1972 1999 Crangonyx pseudogracilis EUR 1998 1999 Grandidierella japonica ASIA 1966 1999 Exopalaemon modestus Siberian prawn EUR-ASIA 1995 1995 Sinelobus cf. stanfordi not known 1943 1943 Melita cf. nitida NA 1941 2003 
LCRANS page 40

Table 4. cont. 

Species Common Name Native Range

1st Western

Collection

1st LCR 

Collection

Mec

Intr

Mechanism abbreviations: AQ = aquarium disposal, OR = ornamental species (escape, release, disposal), RI = release by individual (not considered a

species nor released by a state or federal agency), AX = accidental introduction accompanying intentional introduction, ES = escape from commercial c

wildlife enhancement, intentional by a state or federal agency, SB = solid ballast, BW = ballast water, SF = ship fouling, GS = gradual spread from oth

outside of the river, and BC = biological control organism

VERTEBRATESFish 

Lepomis gibbosus pumpkinseed NA ? 1893 Lepomis gulosus warmouth NA ? 1893 Lepomis macrochirus bluegill NA ? 1893 Micropterus dolomieu smallmouth bass NA 1874 1923 Micropterus salmoides largemouth bass NA ? 1888 Pomoxis annularis white crappie NA ? 1893 Pomoxis nigromaculatus black crappie NA ? 1893 Alosa sapidissima American shad NA 1871 1880s Misgurnus anguillicaudatus Oriental weatherfish ASIA ? 1980s 

Carassius auratus goldfish ASIA ? 1933 AQCtenopharygodon idella grass carp ASIA 1960s 1960s Cyprinus carpio common carp EUR-ASIA 1872 1880 EFundulus diaphanous banded killifish NA ? 1971 Ameiurus catus white catfish NA 1874 1880s Ameiurus melas black bullhead NA 1874 1894 Ameiurus natalis yellow bullheard NA 1874 1905 Ameiurus nebulosus brown bullhead NA 1874 1880s Ictalurus punctatus channel cat NA ? 1920s Morone chrysops white bass NA 1895 ? Morone saxatilis stripped bass NA 1879 1900s Perca flavescens yellow perch NA ? 1894, 1905 Sander vitreus walleye NA 1874 1940s 

Gambusia affinis mosquitofish NA 1960s B

Herptiles 

Chelydra serpentina serpentina Eastern snapping turtle NA ? ? RI, Rana catesbeiana bullfrog NA ? 1914, 1924 Trachemys scripta elegans red eared slider NA ? ? RI, 

Mammals 

Myocaster coypus nutria SA ? 1937 
Due to the limitations of this survey, inadequate taxonomic resolution in prior studies, 

and the abundance of unresolved or cryptogenic taxa, our results are likely to represent a 

conservative estimate of the ANS invasion. Some areas or habitat types in the lower 

Columbia were not well-sampled previously or in this study. Because our surveys were 

shore-based or conducted using small boats, the deep, main channel of the river and the 

salt wedge at the mouth of the estuary were not sampled. We sampled riverbanks, sandy 

islands, and the benthos adjacent to industrial and port facilities, but these areas should be 

subjected to more intensive sampling to better characterize these habitats. 

Some taxa were either under-sampled or were not identified to species. The Nemertea, 

Porifera, Ostracoda, Acarina, Kamptozoa, and aquatic insects were collected but not 

identified to species in most cases. Other data gaps were revealed during analysis of the 

results. We concluded that oligochaetes were under-sampled because 46% (18 of the 39) 

(including native, cryptogenic and introduced species) were collected at only one of the 

134 sampling locations visited over two years. Such a large number of rare species 

suggests that we undersampled a patchy oligochaete habitat (Steve Fend, personal 

communication). In addition, several native oligochaete species reported in our literature 

survey (including one described from the lower Columbia River) were not found in any 

of our samples. 

Other species previously reported in the Columbia but not recorded in our surveys 

included the mysid Alienacanthomysis macropsis (McCabe et al. 1993); a copepod, 

Hansenulus trebax, which is parasitic in the brood chamber of the native mysid Neomysis 

mercedis and described from the Columbia River by Daly and Damkaer (1986); and 

several endemic mollusk species (Appendix B). Experts who evaluated our species lists 

also concluded that some taxa lists may be incomplete because they included few 

mesohaline and marine species, particularly phytoplankton and polychaetes, which 

should be found near the mouth of the river. Our survey results are supplemented by the 

results of the literature review, but some poorly resolved taxa (such as the oligochaetes) 

are still not well-documented in the lower Columbia River.

The large percentage of cryptogenic species (45%) complicates evaluation of the 

magnitude of aquatic bioinvasion of the lower Columbia River, but it is a consequence of 

LCRANS page 41
our strict adherence to precise protocols for assigning organisms to classes. The majority 

of the cryptogenic species were found to belong to taxa that are poorly resolved in the 

Columbia River and elsewhere. The distribution of many species is reported as 

widespread or cosmopolitan without discussion of the possibility that these species were 

spread by human activity. Clarifying the status of cryptogenic species in the Columbia 

River will be difficult until their worldwide distributions are known and evaluations are 

made about where they are native and where they are introduced. For example, prior to 

the publication of Kathman and Brinkhurst (1998) that first described a distribution 

throughout North America, the oligochaete, Amphichaeta sannio, was considered by 

some to be a European estuarine species. In addition, its taxonomy remains in doubt 

(some consider A. sannio, to be synonymous with A. raptisae), which further complicates 

resolution of the classification of this species. As a species with unknown origin and a 

holarctic distribution, we considered it cryptogenic. 

Patterns of Introduction 

Most invertebrates reported from the Columbia River also occur in San Francisco Bay 

but not all of these species are distributed throughout other major West Coast estuaries 

(Table 5)

14. San Francisco Bay has the highest recorded number of nonindigenous 

species in the region (Cohen and Carlton 1995) and nearly all ANS reported elsewhere in 

the eastern Pacific occur in San Francisco Bay (Chapman 2000); however, the 

importance of dispersal of introduced species from San Francisco Bay to other West 

Coast estuaries is unclear (Wasson et al. 2001). Twenty-eight of the 35 introduced 

invertebrates in the lower Columbia River have not been reported in other major bays and 

estuaries on the West Coast. This distinctive assemblage could be the result of unique 

hydrological and physical characteristics of the lower Columbia River. Alternatively, it 

could be a result of differences in sampling effort. For example, rapid assessments 

surveys – those surveys that are conducted over a limited period of time (usually less than 

a week) by a team of species experts to identify both native and introduced species found 

 14 These data were assembled from several major introduced species surveys undertaken in the past 10

years but may not reflect the current, largely unpublished, state of knowledge on species distributions. 

LCRANS page 42
LCRANS page 43

at selected sites - have produced much of the information on introduced species in other 

estuaries, and oligochaetes are rarely identified during rapid assessment surveys. 

Table 5. West Coast distributions of all introduced invertebrates found in the lower Columbia River. 

(Additional data compiled from Cohen and Carlton 1995, Cohen et al. 1998, Ruiz et al. 2000, Cohen 

et al. 2001, CDFG 2004, and NAS 2004.) 

Invertebrate Species SFB CB LCR WB PS 

Location abbreviations: SFB = San Francisco Bay CA, CB = Coos Bay OR, 

LCR = Lower Columbia River, WB = Willapa Bay WA, and PS = Puget Sound WA 

Table abbreviations: Lit = in literature review but not collected by LCRANS 

1 = Found in Humboldt Bay and San Diego Harbor, 2 = Found along the northern California coast, 3 = Found in other 

Northwest freshwater sites, Bold species names indicates species distributed throughout all listed estuaries 

Fredericella indica3 x 

Pectinatella magnifica3 x 

Nematostella vectensis x X x x 

Cordylophora lacustris x X x x x 

Branchiura sowerbyi x x 

Chaetogaster diaphanus x x 

Eukerria saltensis x 

Paranais frici x x 

Stylodrilus heringianus x x 

Hobsonia florida x x x 

Manayunkia aestuarina x x 

Manayunkia speciosa x x 

Polydora cornuta x x x 

Pseudopolydora kempi x X Lit x x 

Streblospio benedicti x X x x x 

Cipangopaludina chinesis malleatus x x 

Potamopyrgus antipodarum (drainage) x 

Corbicula fluminea x X x x 

Mya arenaria x X x x x 

Nuttallia obscurata X x x 

Balanus improvisus x X x x 

Acartiella sinensis x Lit 

Limnoithona sinensis x Lit 

Limnoithona tetraspina x x 

Pseudodiaptomus forbesi x x 

Pseudodiaptomus inopinus X x 

Sinocalanus doerri x x 

Tachidius (Neotachidius) triangulari x 

Nippoleucon hinumensis x X x x x 

Caecidotea racovitzai racovitzai 1 x 

Crangonyx pseudogracilis x 

Grandidierella japonica x X x x x 

Exopalaemon modestus x x 

Sinelobus stanfordi 2 x x 

Melita nitida x X x x x 
LCRANS page 44

Comparisons between the Columbia River, San Francisco Bay and other invaded aquatic 

systems are difficult but inevitable. While they have similar habitat types, it is 

problematic to compare these systems because they differ considerably in their physical, 

chemical, and biological characteristics. Depending upon the taxonomic group 

considered, the lower Columbia River is more invaded than some systems and less than 

others (Figure 9). Unlike the lower Columbia, the Hudson River is dominated by 

introduced plants and mollusks. Except for a smaller number of introduced mollusks, the 

Columbia River appears to be “more invaded” than Puget Sound. These differences 

could result from differences in sampling methods, introduction vectors, invasion 

pressure, habitat types, climates, disturbance regimes, etc. For example, the 

comparatively large number of introduced vascular plants in the Great Lakes and Hudson 

River systems may be a result of longer histories of solid ballast discharge; the success of 

introduced invertebrates in San Francisco Bay could be facilitated by the temperate 

waters of the Eastern Pacific in (Chapman 1997); and the bathymetry of Puget Sound 

could decrease the success of benthic invertebrate establishment. 

Macroalgae Vascular Plants Annelids Mollusks Crustaceans

0

10

20

30

40

50

60

70

80

90

100

Puget Sound

Columbia River

San Francisco Bay

Great Lakes

Hudson River

Figure 9. Comparison of invasive species in several North American systems (Mills et al. 1993, Cohen 

and Carlton 1995, Mills et al. 1995, Cohen et al. 1998, and Cohen at al. 2001). 
LCRANS page 45

Rates of Invasion 

The number of introduced species found in the lower Columbia River is increasing 

(Figure 12), and mirrors similar trends observed elsewhere (Ruiz et al. 2001); however, 

the rate of introduced invertebrate discovery and reporting probably does not represent 

the actual introduction rates. The lower Columbia invertebrate community was poorly 

studied in the past and the presence of nonnative species may have been overlooked. 

Furthermore, some of the introduced species found in our survey were undoubtedly in the 

Columbia River for several years prior to recent reports. For example, the New Zealand 

mudsnail, Potamopyrgus antipodarum, was present in the Snake River since the mid 

1980s and was almost certainly transported downstream from the Snake River at some 

earlier date than its first discovery near Astoria in 1995 (Wonham and Carlton 

unpublished). The Chinese mystery snail, Cipangopaludina chinesis malletus, has been a 

popular aquarium/pet species for well over 50 years (Cohen and Carlton 1995) and 

anecdotal evidence supports a presence in protected waters of the Columbia River basin 

long before our sighting in 2002. It is also probable that the invertebrate curve reflects 

sampling effort, in part, which has increased in the last 20 years. 

0

5

10

15

20

25

30

35

1800 1850 1900 1950 2000

Species accumulation

Year of discovery

Fish

Invertebrates

*

Figure 10. Accumulation of non-indigenous species in the lower Columbia by year of discovery. 

In contrast to the rate of nonative invertebrate discovery, the rate of nonnative fish 

introductions in the river may approximate the actual in introduction rate. Prior to 1955, 

the majority of fish introductions were intentional, often conducted by the U.S. Fish 
LCRANS page 46

Commission, and well-documented (Smith 1896, Lampman 1946). After 1955, 

intentional sport fish introductions declined but new introductions for biological control, 

e.g., the mosquito fish, Gambusia affinis (Bond 1994), or illegal aquarium disposal, e.g., 

the oriental weather loach, Misgurnus anguillicaudatus (Logan et al 1996), continue to be 

reported. Furthermore, new and unusual species (e.g. piranha which cannot survive over 

winter in cold water and are not considered successful introductions) caught by anglers 

often receive media attention and are reported as novelties (Quinn 2002). 

Vectors and Pathways 

Nonnative species have been introduced into the lower Columbia River intentionally and 

unintentionally through a variety of vectors (Figure 10). Although vector determination 

is not precise, shipping-related vectors accounted for the largest number of introduced 

species. Ballast water alone was considered to be a possible mechanism of introduction 

for 29 out of 35 invertebrate species and one plant into the Columbia River. All shipping 

mechanisms together (fouling, solid ballast, and ballast water) accounted for 30 

invertebrates and two aquatic plants. Intentional releases for wildlife enhancement by 

individuals and fisheries agencies accounted for 19 out of 23 fish introductions to the 

lower Columbia River. Similarly, many aquatic plant introductions could be attributed to 

intentional introduction but could also have escaped from ornamental cultivation (Figure 

11, Table 4). Many species are associated with multiple mechanisms. For example, the 

population of the common goldfish, Carassius auratus, in the lower Columbia River may 

be the result of aquarium dumping, escape from ornamental ponds, and/or release by an 

individual for wildlife enhancement. Intentional introduction and escape from culture 

ponds were documented for the common carp, Cyprinus carpio (Lampman 1949). 
Aquarium

Ornamental Pond

Release by an Individual

Accidental

Escape

Fishery Enhancement

Solid Ballast

Ballast Water

Ship Fouling

Gradual Spread

Biological Control

0

5

10

15

20

25

30

35

Number of species

Plants

Vertebrates

Invertebrates

Figure 10. Invasions by type of introduction mechanism.

The importance of various vectors for introduction of invertebrates has changed over time 

(Figure 11). Shipping-related vectors have increased in importance since 1950. The 

increase in introductions associated with shipping corresponds with an increase in the 

volume and speed of shipping in the Columbia. Invertebrate introductions that could be 

attributed to aquarium dumping and individual release occurred only after 1999, although 

anecdotal evidence suggests that this vector was active earlier as well. 

Shipping Ornamental or Aquarium Accidental Individual Release Gradual Spread

0

5

10

15

20

25

30

1850 - 1899

1900 - 1949

1950 - 1998

1999 - Present

Figure 11 Changes in invertebrate introduction vectors over time. 

LCRANS page 47
The majority of introduced species in the lower Columbia originated in North America 

(Figure 12). Introduced fish accounted for most of the species with North American 

origin. Europe, Asia, and South America supplied similar numbers of plants as North 

America. Europe and Asia provided similar numbers of invertebrates as North America. 

No fish or invertebrates originated in Africa, and no fish or plants originated in New 

Zealand/Australia. North America

South America

Africa

Europe

Asia

Australia/New Zealand

Unknown

0

5

10

15

20

25

30

35

40

Number of Species

Plants

Fish

Invertebrates

Figure 12. Invasions by region. This figure contains species collected by LCRANS as well as those 

species from the WEMAP study and the literature review that are considered valid. 

Asia was the native region of 34% of the invertebrates introduced via shipping vectors in 

the Columbia River (Figure 13). The role of shipping in these introductions was 

supported by data on shipping traffic in the Columbia River. Ninety-four percent of all 

transoceanic voyages to Oregon ports originate in Asia, i.e., Japan, Korea, China and 

Taiwan (Flynn and Sytsma 2004). 

LCRANS page 48
Asia

Eurasia

Europe

North Atlantic

North America

South America

Unknown

Figure 13. Origins of ballast water introduced invertebrate species in the lower Columbia River.

Despite an apparent correlation between volume of shipping from Asia and the 

preponderance of Asian species in the invertebrate community in the lower Columbia 

River, the source of these populations may not be their native ranges in Asia. Many 

recent ballast water introductions were previously established elsewhere on the West 

Coast (Table 5). The Columbia River receives more port calls from vessels from these 

domestic ports (59%) than it does from international ports (Flynn and Sytsma 2004). 

About 25 percent of coastal vessel traffic coming into Oregon estuaries originated in the 

highly invaded San Francisco Bay/Sacramento/San Joaquin Delta (Flynn and Sytsma

2004). Short transit times, established populations of introduced invertebrates possibly 

selected for dispersal by shipping vectors in several domestic ports on the West Coast, 

and abundant shipping traffic suggests that domestic shipping is a highly important vector 

for ANS introduction to the Columbia River. According to the dates of first discovery, 

most ANS in the lower Columbia River were reported earlier from other locations on the 

West Coast. Discovery dates, however, represent detection rather than arrival and are 

heavily influenced by sampling effort and regional ANS awareness. 

The Columbia River is probably a net importer of ballast water and associated organisms. 

Columbia River ports are primarily bulk shipping ports, bulkers contain more ballast 

water than other ship types, and bulkers typically enter the Columbia River without cargo 

and in-ballast (Flynn and Sytsma 2004). Still, ships do take on ballast water in the 

Columbia. The role of the Columbia River in regional and global dispersal of ANS 

requires further investigation. 

LCRANS page 49
Chapter 6: Conclusions and Recommendations 

We determined that 81 aquatic species were introduced into the lower Columbia River 

since the 1880s. The majority of these species were fish (28%), aquatic plants (23%) and 

crustacea (15 %). The remaining 18% was a combination of mollusks, annelids, 

bryozoans, cnidaria, amphibians, reptiles and an aquatic mammal. These results were 

likely a conservative estimate of the number of ANS in the river because of limitations of 

the survey, inadequate taxonomic resolution in prior studies, and the abundance of 

unresolved and cryptogenic taxa. 

Over the course of our field survey we documented 269 aquatic species (and 55 other 

distinct organisms that we were unable to identify at the species level) in the lower 

Columbia River. Of the 269 species identified, 54 (21%) were introduced, 92 (34%) 

were native, and 123 (45%) were cryptogenic. From the 1880s to the 1970s a new 

introduced species was discovered in the lower Columbia about every five years. The 

frequency of new discoveries ANS is increasing worldwide (OTA 1993, Ruiz et al. 

2000), however, and the rate of discovery of introduced invertebrates in the lower 

Columbia River mirrors this trend. Over the past ten years a new invertebrate species 

was discovered about every five months. The increasing rate of new discovery is due to 

increasing frequency of introductions and to the number and type of surveys conducted. 

It is not possible to separate these effects from the available data 

In contrast to the invertebrates, the rate of fish discoveries in the lower Columbia 

declined after the 1950s. For fish, the rate of discovery may parallel introduction rates 

because many introductions were well-documented. The reduction in fish introductions 

was likely due to a decline in intentional fish stocking by individuals and fish and game

agencies to increase the diversity of food and game fishes. 

The majority of introduced species in the lower Columbia originated in North America. 

Introduced fish accounted for most of the species with North American origin, while Asia 

was the native region of 34 percent of the invertebrates introduced via shipping vectors. 

Ballast water was the probable vector responsible for introducing 29 of 35 nonnative 

invertebrates. Most invertebrates reported from the Columbia River also occur in San

Francisco Bay. Seven of the 35 invertebrates introduced into the lower Columbia River 

LCRANS page 50
are widespread in major bays and estuaries of the West Coast. Additional surveys may 

increase this number. 

The Columbia River receives more port calls from vessels from domestic ports (59 

percent) than it does from international ports (Flynn and Sytsma 2004). About 25 percent 

of coastal vessel traffic coming into Oregon estuaries originated in the highly invaded 

San Francisco Bay/Sacramento/San Joaquin Delta (Flynn and Sytsma 2004). Short 

transit times, established populations of introduced invertebrates possibly selected for 

dispersal by shipping vectors in several domestic ports on the West Coast, and abundant 

shipping traffic suggests that domestic shipping is a highly important vector for ANS 

introduction to the Columbia River. 

Additional surveys 

This report establishes a baseline on ANS in lower Columbia River. Additional 

monitoring and sampling is necessary to detect new invasions and to document invasion 

rate, impacts, and efficacy of management efforts. We recommend a multiple purpose

sampling approach to maximize the potential of detecting additional species and new 

arrivals. Sampling should target habitats and taxa that are likely to contain new invaders 

every year; a synoptic survey of the lower Columbia River should be conducted every 

five years; and additional sampling should target data gaps and survey limitations of this 

project. Regular comprehensive sampling of incoming ballast water is also needed to 

evaluate the probability of new introductions deriving from this vector. 

Targeted sampling

Targeted sampling should focus on tracking changes in habitats that are highly invaded 

and are considered hot spots for detecting new arrivals. Targeted taxa include benthic 

crustaceans, mollusks, polychaetes, hydroids, zooplankton, and aquatic vascular plants. 

Sampling should replicate the protocols followed by in this survey. The locations in 

Table 9 are hot spots of invasion and/or have good, long-term records of species 

composition. These locations are recommended for targeted sampling. 

LCRANS page 51
Table 6. Suggested sampling locations proposed for targeted sampling. 

Location Sites Prior Research Comments

Youngs Bay CEDC Net Pens CREDDP, benthic 

surveys by CEDC, 

LCRANS, nearby

surveys by NMFS, 

EMAP 

Brackish water, benthic surveys 

demonstrate interactions between 

mudsnail invaders and native

crustacean community. 

Youngs River Mouth CREDDP, LCRANS, 

EMAP, Cordell et al. 

Changes in freshwater and low salinity 

zooplankton community 

Trestle Bay Interior NMFS, LCRANS Protected embayment with soft 

sediment, salt marsh and rocky

intertidal community along jetty. 

Baker Bay Sand Island LCRANS High salinity site, close to mouth but 

partially protected, several ANS found

in island pools 

Eastern mud flats LCRANS, EMAP Extensive exposed meso-polyhaline 

mud flats, unique benthic invertebrate

community vs. other mud flats in

estuary 

Miller Sands Interior NMFS, ACE, 

LCRANS 

Artificially established freshwater sand 

habitat, interior is shallow, protected

and adjacent to main shipping channel

Cathlamet Bay Russian Island NMFS, EMAP, 

LCRANS 

Protected tidally influenced freshwater 

mudflats upstream of primary

anchorage site for commercial vessels. 

Port of Longview Potential site for ANS introductions via 

ballast water 

Port of Portland Potential site for ANS introductions via 

ballast water 

Sloughs Wallace, Westport, 

Skamania, Fisher 

Island etc. 

LCRANS Slow, protected waters in the transition

zone between the Willamette 

confluence and the estuary may retain

species released at the Ports of Portand, 

Vancouver and Longview/Kelso 

Sauvie Island Multnomah Channel

Side 

LCRANS Potential hot spot for aquarium and

ornamental plant disposal, warm water 

area 

Columbia Slough ODFW, LCRANS Potential hot spot for aquarium and 

ornamental plant disposal, high

nutrient, warm water area with limited

seasonal flushing, hot spot for

Exopalaemon modestus, etc. 

Discrete sampling

The goal of the discrete sampling should be to use intensive surveys resolve the data gaps 

and sampling limitations encountered in this survey. Sampling should focus on undersampled taxa and areas such as the mouth and main channel of the estuary where 

LCRANS was unable to sample. Discrete sampling results should be used to modify 

targeted sampling if new hot spots or species are discovered. 

LCRANS page 52
Synoptic surveys

A repeat of the synoptic survey reported on here, should be conducted every five years. 

The goals of the survey should be to investigate potential new hotspots of invasion and to 

update the database on ANS developed through review of the literature. The synoptic 

survey should be used to fine-tune sampling methods and protocols to ensure complete 

coverage of taxa and habitats in the river. 

Research Needs 

Understanding the ecology, biology, dispersal of ANS is critical to management of 

invasions and protection of native plant and animal communities. Some research 

recommendations include investigation of: 

• Facilitation – Major anthropogenic alteration of the physical, chemical, and 

hydrological characteristics of the lower Columbia River have occurred in the last 

century. Additional changes in these characteristics, as well as climate change, 

can be anticipated. The importance of various vectors of dispersal, human and 

natural, may also vary. Do these changes enhance establishment of ANS? 

• Impacts – While economic and ecological impacts of ANS that are ecological 

engineers, like zebra mussels, are readily apparent, impacts of other species may 

be less obvious but still have significant ecological consequences. What are the 

economic and ecological effects of ANS? Do invaders at some trophic levels or 

in specific guilds have greater impacts than others? 

• Taxonomy and biogeography– Taxonomic resolution of many species is poor, 

which limits conclusions about the number and rate of introduction of ANS. 

Biogeography of many species is also poorly documented. Taxonomic expertise 

on many taxa is limited. Are the large numbers of cryptogenic species found in 

the lower Columbia introduced or native? What is the number and importance of

introduced disease organisms, parasites (plant and animal) and aquatic insects in 

the lower Columbia? 

• Disperal of ANS – Movement of ANS in ballast water transferred between 

domestic ports is a particular threat to the Columbia River. Other vectors may be 

equally important, but are not well documented. What is the role of coastal 

shipping in dispersal of ANS on the West Coast? What is the role of shippingrelated vectors other than ballast water, e.g., hull fouling, in dispersal of ANS? 

• Management of ANS Prevention of new invasions requires interdiction of 

pathways through regulation of vectors. What methods can be used to manage 

populations of potential ANS in ballast water, hull fouling, live aquatics, 

ornamental and aquarium, and other vectors? 

LCRANS page 53
Management Needs 

Invasive species management targets introduction, establishment, further spread and

impacts of ANS. While the tools to control populations at the latter three stages include 

chemical, biological, and mechanical options – preventing introductions is the best and 

most cost effective way to limit the negative impacts of invasive species Eradication and 

often control of ANS in open systems has proved nearly impossible and many ANS 

management options are simply aimed at lessening the impacts of these species, usually 

by buffering the affected resource, without reducing overall population densities (i.e. 

retrofitting water-intake pipes to diminish zebra mussel fouling). In order to better focus 

ANS management of the lower Columbia River we have identified the following needs: 

• Evaluation of vectors and pathways - While ballast water and other shipping 

activities appear to dominate recent ANS introductions into the lower 

Columbia River, other vectors, especially intentional releases, remain poorly 

quantified. New ballast water regulations (Flynn and Sytsma 2004) should 

reduce the frequency of ballast water introductions, which will lead to an 

increase in the relative importance of escape, release, and disposal of ANS by 

individuals will increase. We also need policies or guidelines that that address 

those individual behaviors that contribute to both intentional and unintentional 

introductions of ANS. . 

• Compliance data - Without compliance numbers it is difficult to estimate the 

current effectiveness of ballast water management and other vessel 

management guidelines. Our study demonstrates the prominent role ballast 

water has played recently in the introduction of ANS into the lower Columbia 

River but because this represents the first comprehensive survey of ANS in

the area it is difficult to determine if federal guidelines or state ballast water 

management legislation has had an effect on ANS introductions. 

• Export risk evaluation - It is important that we view the lower Columbia River 

as a source of invaders and develop management actions aimed at preventing 

export as well as import. This includes not only native species that may be 

exported to other continents, but also nonnative species established in the 

lower Columbia River that may be transported to other nearby coastal waters 

• Facilitation activity evaluation - As part of a comprehensive ANS 

management plan for the lower Columbia River it is vital that future and 

ongoing environmental modifications of the region be evaluated as actions 

that may enhance existing or facilitate new ANS invasions. This includes 

projects such as dredging, diking, flow alteration, water impoundment and 

removal, and even habitat restoration activities. Along with dramatic habitat 

disturbance, restoration, dredging and other ventures may require bringing in 

equipment and personnel that act as transportation vectors for hitchhiking 

ANS. In other instances the removal of pest species such as emergent aquatic 

LCRANS page 54
plants may just open up new habitat for other invasive species. An important 

step in the management of ANS is the evaluation of such projects in light of 

potential ANS impacts. This may require incorporating ANS into impact 

statements as well as monitoring plans. The more we know about how 

modifications to the Columbia River effect existing ANS populations the 

more tools we will have to manage future introductions. 

LCRANS page 55
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