Behavior and Movement of Adult Summer Steelhead 

Following Collection and Release, Lower Cowlitz River, 

Washington, 2012–2013

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2013–1116
Cover: Photograph showing steelhead anglers near the Barrier Dam on the lower Cowlitz River, 

Washington, March 22, 2008. Inset photograph is an adult summer steelhead from the lower Cowlitz 

River, Washington, August 13, 2012. Photographs taken by Tobias Kock, U.S. Geological Survey. 
Behavior and Movement of Adult Summer Steelhead 

Following Collection and Release, Lower Cowlitz River, 

Washington, 2012–2013

By Tobias J. Kock, Theresa L. Liedtke, Brian K. Ekstrom, and Dennis W. Rondorf, U.S. Geological Survey; Chris 

Gleizes and Wolf Dammers, Washington Department of Fish and Wildlife; and Scott Gibson and Jamie Murphy, 

Tacoma Power

Open-File Report 2013–1116

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Kock, T.J., Liedtke, T.L., Ekstrom, B.K., Rondorf, D.W., Gleizes, C., Dammers, W., Gibson, S., and Murphy, J., 

2013, Behavior and movement of adult summer steelhead following collection and release, lower Cowlitz River, 

Washington, 2012–2013: U.S. Geological Survey Open-File Report 2013-1116, 22 p.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain

copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be 

secured from the copyright owner.
iii

Contents

Executive Summary.................................................................................................................................................... 1

Introduction................................................................................................................................................................. 3

Methods...................................................................................................................................................................... 4

Fish Tagging and Release ...................................................................................................................................... 4

Fish Monitoring ....................................................................................................................................................... 7

Results........................................................................................................................................................................ 9

Run Size, Run Timing, and River Flows.................................................................................................................. 9

Hatchery Returns .................................................................................................................................................. 12

Angler Harvest ...................................................................................................................................................... 14

Effect of Release Timing and River Flow on Fate of Recycled Steelhead ............................................................ 14

Radiotelemetry...................................................................................................................................................... 17

Temporal Effectiveness of Opercle Punches ........................................................................................................ 18

Discussion ................................................................................................................................................................ 19

Acknowledgments..................................................................................................................................................... 21

References Cited...................................................................................................................................................... 22

Figures

Figure 1. Schematic of the lower Cowlitz River and tributaries, Washington, that were monitored for the 

presence of radio-tagged adult steelhead during an evaluation in 2012.................................................................... 5

Figure 2. Photographs showing a Floy®-tagged steelhead that was being opercle punched (top); a fresh 

opercle punch and a radio transmitter antenna exiting the fish mouth ( transmitter was located inside the fish 

and is not visible) (middle); and an opercle punch that had closed from tissue re-growth (bottom)........................... 6

Figure 3. Arrival timing of adult summer steelhead at the Cowlitz Salmon Hatchery, Washington, 2008–2012...... 10

Figure 4. Graphs showing daily river flows (thousand cubic feet per sec [k ft3/s]; top) measured near 

Mayfield Dam (USGS streamgage No. 14238000) during June–December 2012 (black line) and average 

river flows during the same period from 2008 to 2011 (gray line); the relationship between 2012 and 

average 2008–2011 flows (bottom) ......................................................................................................................... 11

Figure 5. Graphs showing percentage of recycled steelhead that returned to the hatchery or were caught by 

anglers (top) and run timing for summer steelhead in the Cowlitz River based on the number of fish that were 

collected at the Cowlitz Salmon Hatchery (bottom), lower Cowlitz River, Washington ............................................ 13

Figure 6. Graph showing percent of recycled steelhead from each release group that returned to the hatchery, 

were caught by anglers, or were not known to be removed from the lower Cowlitz River, Washington, 2012......... 15

Figure 7. Graphs showing number of fish that returned to the hatchery (top graph) or were caught by anglers 

(bottom graph) each day (gray bars) and daily river flows (black line) during a study on the lower Cowlitz River , 

Washington, 2012................................................................................................................................................... 16

Figure 8. Graph showing percentage of radio-tagged fish observed making trips between the Trout Hatchery and 

the Barrier Dam during a study on the lower Cowlitz River, Washington, 2012....................................................... 18

Figure 9. Graph showing relationship between the inside diameter of opercle punches of adult steelhead and 

the elapsed time in days (d) since tagging for a study on the Cowlitz River, Washington, 2012.............................. 19
iv

Tables

Table 1. Tagging dates and numbers of adult hatchery steelhead that were marked for an evaluation on the lower 

Cowlitz River, Washington, 2012............................................................................................................................... 7

Table 2. Summary of the fate of recycled steelhead that were released for a study on the Cowlitz River, 

Washington, 2012.................................................................................................................................................... 12

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)
1

Behavior and Movement of Adult Summer Steelhead 

Following Collection and Release, Lower Cowlitz River, 

Washington, 2012–2013

By Tobias J. Kock, Theresa L. Liedtke, Brian K. Ekstrom, and Dennis W. Rondorf, U.S. Geological Survey; Chris 

Gleizes and Wolf Dammers, Washington Department of Fish and Wildlife; and Scott Gibson and Jamie Murphy, 

Tacoma Power

Executive Summary

Historically, adult summer steelhead Oncorhynchus mykiss returning to hatcheries on the lower 

Cowlitz River were sometimes transported and released in the river (recycled) to provide additional 

angling opportunity for the popular sport fishery in the basin. However, this practice has not been used 

in recent years because of concerns associated with interactions between hatchery fish and wild fish.

Fishery managers were interested in resuming recycling but lacked information regarding effects of this 

practice on wild steelhead so we conducted a study during 2012–2013 to: (1) enumerate recycled 

steelhead that returned to the hatchery or were removed by anglers; and (2) determine if steelhead that 

were not removed from the river remained in the system where they could interact with wild fish.

During June–August 2012, a total of 549 summer steelhead were captured at the Cowlitz Salmon 

Hatchery, tagged, and released downstream near the Interstate 5 Bridge. All recycled steelhead were 

tagged with a white Floy® tag and opercle-punched; 109 (20 percent) of these fish also were radiotagged. All adult steelhead that return to the hatchery were handled by hatchery staff so recycled 

steelhead that returned to the hatchery were enumerated daily. A creel survey and voluntary angler 

reports were used to determine the number of recycled steelhead that were caught by anglers. We 

established three fixed telemetry monitoring sites on the mainstem Cowlitz River and eight additional 

sites were deployed on tributaries to the lower Cowlitz River where wild winter steelhead are known to 

spawn. We also conducted mobile tracking from a boat during October 2012, November 2012, and 

January 2013 to locate radio-tagged fish.

A total of 10,722 summer steelhead were captured at the Cowlitz Salmon Hatchery in 2012, 

which was the largest return since 2008. River flows during much of the study period were similar to 

2008–2011 average flows, however, high-flow periods in July and November 2012 were nearly twice as 

high as the 2008–2011 average flows. We determined that 50 percent (273 fish) of the recycled 

steelhead returned to the hatchery and 18 percent (102 fish) of the recycled steelhead were caught by 

anglers. Most (243 fish; 89 percent) of the recycled steelhead that returned to the hatchery were 

recollected during July–August. The average elapsed time from release to recapture at the hatchery was 

9 days (d) and 72 percent (182 fish) of the fish returned to the hatchery within 14 d of release. These 

trends were similar for recycled steelhead that were caught by anglers. Most fish were caught during 

July–August and the median time from release to capture was 10 d. We determined that 65 percent (70 

fish) of the angler-caught fish returned to the hatchery within 14 d of release. River flows appeared to 
2

affect both hatchery returns and angler catch. The daily number of recycled steelhead that were 

recollected at the hatchery were low during periods when river flows were decreasing and high during 

periods when river flows were increasing. Conversely, daily angler catch of recycled steelhead generally 

was low when flows were increasing and high when flows were decreasing.

We determined that 32 percent of the recycled steelhead (174 fish) were not removed from the 

lower Cowlitz River, based on observations from hatchery returns and angler reports, but results from 

the radio-tagged fish were insightful for understanding what may have happened to these fish. By 

comparison, we determined that 24 percent of the radio-tagged fish were not known to have been 

removed from the river. We determined that 12 percent of these fish were actively moving in the lower 

Cowlitz River during October 2012–January 2013. None of the radio-tagged fish were detected in 

tributaries during the study period except for a single fish that spent approximately 7 d in the Toutle 

River during early September. During October 2012–January 2013, 10 percent of the radio-tags from 

recycled steelhead were detected near popular fishing areas, and 2 percent of the radio-tagged steelhead 

were never detected during the study period. We suspect that a large proportion of these fish may have 

been harvested and not reported, or died.

Detection patterns of radio-tagged steelhead showed that most fish (82 percent) moved upstream 

from the release site and were detected at the Trout Hatchery and the Barrier Dam sites. The median 

time from release to detection at these sites was 3.7 d and many of these fish made multiple trips 

between the two sites. Nearly one-third (29 percent) of the recycled steelhead that were detected at the 

Trout Hatchery and the Barrier Dam made at least two trips between the sites and some fish made as 

many as six trips. Radio-tagged fish that remained in the lower Cowlitz River during the spawning 

period (December 2012–January 2013) were observed in the river reach between the mouth of 

Ostrander Creek (river mile 10) and the Trout Hatchery (river mile 44).

During this study, we collected data on opercle punch regrowth rates to understand the temporal 

effectiveness of this marking technique. We took opercle measurements for a total of 190 fish during the 

study. Fresh opercle punches were measured for 63 fish at the time of marking, and the remaining 127 

fish were measured when fish returned to the hatchery. We determined that opercle punches remained 

open for about 30 d. The holes appeared to regrow slowly in the first 20 d after marking, but regrowth 

accelerated during the 20–30 d post-marking period. After 30 d, all opercle punches that we observed 

had completely closed due to tissue regrowth. 

Our study showed that a large proportion (68 percent) of the recycled steelhead were removed 

from the lower Cowlitz River. These fish primarily entered the hatchery or were caught by anglers 

within 14 d of release, which suggests that they present minimal risk to wild fish in the system.

However, the remaining fish (32 percent) could not be accounted for, which may complicate fisheries 

management decisions associated with recycling summer steelhead. Findings from the radiotelemetry 

study suggest that unreported harvest or mortality could explain a large proportion of those fish that 

were not reported as having been removed from the river. Furthermore, intensive monitoring of the key 

spawning tributaries failed to detect a single fish during the spawning period. These findings were 

supported by observations from weir traps operated by the Washington Department of Fish and 

Wildlife. Our findings indicate that additional research may be warranted to further examine the effects 

of recycling hatchery summer steelhead in the lower Cowlitz River. 
3

Introduction

The management of many Pacific salmon Oncorhynchus spp. populations is complicated by the 

conflicting need to maintain production of hatchery-produced (hereafter hatchery) fish while also 

protecting or rebuilding stocks of naturally produced (hereafter wild) fish. Hatchery salmon production 

is necessary to support harvest in many rivers throughout the Pacific Northwest, western Canada, and 

Alaska because many of the wild salmon populations in these areas have declined to levels where 

extinction is possible. However, efforts to maintain hatchery salmon populations and rebuild wild 

salmon populations often conflict. Hatchery salmon have been shown to influence wild salmon through 

predation, competition for space and resources, and by lowering the fitness of wild populations where 

interbreeding occurs (Hindar and others, 1991; Waples, 1991; Berejikian and others, 1996; Noakes and 

others, 2000; Naman and Sharpe, 2012; Rand and others, 2012). Given these concerns, contemporary 

fisheries management strategies for hatchery salmon typically try to reduce impacts that could 

jeopardize wild salmon in a given system.

Steelhead Oncorhynchus mykiss are an important resource in the Cowlitz River, a primary 

tributary to the lower Columbia River, in southwestern Washington State. The Cowlitz River supports 

three distinct steelhead populations including wild winter, hatchery winter, and hatchery summer stocks.

Adult wild and hatchery winter steelhead return to the system during December–April and spawn during 

March–May. Adult hatchery summer steelhead return during May–October and spawn primarily during 

December–January. Wild winter steelhead in the Cowlitz River are currently listed as threatened under 

the U.S. Endangered Species Act (Lower Columbia River evolutionary significant unit [ESU]; National 

Marine Fisheries Service, 2011), whereas adult hatchery (winter and summer stocks) steelhead support 

popular sport fisheries in the system.

Historically, some of the summer steelhead that returned to the hatchery during the early portion 

of the run (June–July) were collected and transported downstream to a release site on the lower Cowlitz 

River. This strategy was referred to as “recycling” and supplemented the number of adult hatchery 

steelhead in the system, thereby increasing angling opportunity. During recent years, steelhead recycling 

has not occurred because of the perceived risks to wild fish. Definitive studies have not been conducted 

on the lower Cowlitz River to quantify recycled hatchery steelhead that remained in the system, or to 

determine if these fish interacted with wild fish. This type of evaluation was of interest to the 

Washington Department of Fish and Wildlife (WDFW) because the recycling program could benefit 

anglers in the lower Cowlitz River if research showed that recycled summer steelhead were not 

affecting wild winter steelhead.

We conducted an evaluation during 2012–2013 to determine the fate of recycled summer 

steelhead in the lower Cowlitz River. Recycling adult summer steelhead has two primary consequences 

of interest: (1) increased angler opportunity and harvest if recycled steelhead are caught by anglers; and 

(2) increased risk to wild winter steelhead populations if recycled fish are not caught by anglers, remain 

in the system, and compete against, or spawn with wild winter steelhead. Given these potential 

consequences, the goals of this study were to monitor the behavior and movement of recycled steelhead 

and to quantify the fish that returned to the hatchery fish trap, were caught by anglers, or remained in 

the Cowlitz River (or a tributary of the Cowlitz River) where they could potentially interact with wild 

steelhead.
4

Methods

Fish Tagging and Release

A total of 549 adult summer steelhead were captured at the Cowlitz Salmon Hatchery (river mile 

[rm] 51; fig. 1), tagged, and then transported downstream and released into the lower Cowlitz River (rm 

30). Each fish was tagged with a white Floy® tag (Model FD-68BC; Floy® Tag, Inc., Seattle, 

Washington) near the dorsal fin, and a single 6-mm diameter hole was created in the operculum 

(hereafter opercle punch) using a hand punch (fig. 2). We also tagged 109 (20 percent) of these fish with 

a radio transmitter (Model Pisces; Sigma Eight Inc., Newmarket, Ontario) to monitor behavior and 

movement patterns during the study. A total of 10 tagging and release events were conducted during 

June–August 2012 (table 1). On each tagging date, adult summer steelhead were collected by hatchery 

staff as part of the daily collection process. Groups of fish (approximately 20 fish per group) were 

crowded into a large basket and anesthetized using the hatchery’s electroanesthesia system. Each batch 

of fish was then sorted and summer steelhead were selected for tagging if they had not previously been 

tagged. Each fish was measured for fork length to the nearest centimeter, visually categorized as male or 

female, and then Floy® tagged and opercle punched. Fish that received radio transmitters also were 

tagged during this time. All tagged fish were then placed into a hatchery holding tank where they were 

held for approximately 24 h. On each release date, tagged fish were loaded onto large fish-hauling 

trucks, transported downstream, and released at the Interstate 5 boat ramp (fig. 1).

Opercle punches are popular fish marking techniques because they are inexpensive and can be 

easily identified when fish are handled and visually examined. However, they are not a permanent 

marking technique because the hole can eventually close because of tissue regrowth. Although opercle 

punches commonly are used, there was little information regarding regrowth rates; so we collected data 

during this study to better understand the temporal effectiveness of the technique. We used a digital 

electronic caliper to measure the inside diameter of a subset of opercle punches when fish were tagged 

or re-collected at the hatchery. These measurements were paired with Floy® tag identification numbers 

so that we could determine the elapsed time between tagging of the fish and re-collection when the 

opercle punches were measured.
5

Figure 1. Schematic of the lower Cowlitz River and tributaries, Washington, that were monitored for the presence 

of radio-tagged adult steelhead during an evaluation in 2012. The locations of fixed radiotelemetry monitoring sites 

(squares), creel survey sites (circles), and the fish release site (triangle) are shown.

Release

Site

Toutle

River

Salmon Cr.

Ostrander Cr.

Cowlitz

Mouth

Columbia River

Coweeman River

Toutle River (rm 20)

Ostrander Creek

Arkansas

Creek

Delameter

Creek

Olequa

Creek

Lacamas

Creek

Salmon Creek

Brights

Creek

Barrier Dam

(rm 51)

Salmon

Hatchery

Trout

Hatchery

Interstate 5 boat ramp (rm 30)

Longview (rm 0)
6

Figure 2. Photographs showing a Floy®-tagged steelhead that was being opercle punched (top); a fresh opercle 

punch and a radio transmitter antenna exiting the fish mouth ( transmitter was located inside the fish and is not 

visible) (middle); and an opercle punch that had closed from tissue re-growth (bottom). Photographs taken by 

Tobias J. Kock, U.S. Geological Survey, July 23, 2012.
7

Table 1. Tagging dates and numbers of adult hatchery steelhead that were marked for an evaluation on the lower 

Cowlitz River, Washington, 2012. 

Tagging date

Number of fish that were 

radio-tagged, Floy®- tagged, and opercle punched

Number of fish that were 

Floy® tagged and opercle punched

Total number of 

fish marked and 

released

June 18 12 25 37

June 25 1 30 31

July 2 16 40 56

July 9 5 50 55

July 16 15 65 80

July 23 7 70 77

July 30 17 60 77

August 6 3 50 53

August 13 25 30 55

August 20 8 20 28

Totals 109 440 549

Fish Monitoring

We collected data on recycled steelhead using three primary approaches during 2012: (1) 

monitoring at the hatchery to quantify recycled steelhead that were recollected; (2) conducting a creel 

survey and collecting voluntary angler reports to estimate the number of recycled steelhead that were 

caught by anglers; and (3) monitoring movements of radio-tagged fish through fixed monitoring sites 

(hereafter fixed sites) and mobile tracking.

The fish trap at the Cowlitz Salmon Hatchery was operated 5 days per week (Monday–Friday) 

and hatchery personnel examined summer steelhead that were captured in the trap during June–

December 2012 to identify recycled fish. Recycled steelhead were identified by the presence of at least 

one of the three tags or marks (that is, white Floy® tag, opercle punch, or radio transmitter) used during 

our study. Floy® tags and radio transmitters can be shed and opercle punches can close from tissue 

regrowth (fig. 2), and in some cases, fish were identified based only on the presence of a closed opercle 

punch. When recycled steelhead were encountered at the hatchery, the Floy®-tag and radio-tag (when 

present) were removed and the identification numbers and recapture date were recorded. If a steelhead 

returned without a Floy® tag or radio transmitter then only the recapture date was recorded. Recycled 

steelhead that were encountered in the fish trap were retained at the Cowlitz Salmon Hatchery and not 

re-released into the lower Cowlitz River.
8

A creel survey and voluntary angler reporting were used to quantify recycled steelhead that were 

captured and retained in the fishery during the study period. The creel survey was conducted during 

June–December 2012. Angling is popular throughout the lower Cowlitz River so we attempted to visit 

multiple sites on each survey date to maximize the number of anglers interviewed and to account for 

spatial differences in harvest. Creel surveys targeted popular fishing locations in the lower Cowlitz 

River including the Barrier Dam (rm 51), Trout Hatchery (rm 44), Mission Bar (rm 37), the Interstate 5 

boat ramp (rm 30), Olequa Creek (rm 25), the mouth of the Toutle River (rm 20), the town of Castle 

Rock (rm 17), and Camelot (rm 15; fig. 1). Anglers were interviewed to determine the number of hours 

fished and the number of fish that were caught. Adult steelhead that were retained by anglers were 

enumerated and recycled steelhead were identified and enumerated using criteria previously described.

We also distributed information about the study to local fishing shops, on regional fishing websites, and 

at popular boat ramps and fishing locations in the system so that anglers could voluntarily report 

information when recycled steelhead were caught.

We established three fixed radiotelemetry sites on the mainstem lower Cowlitz River and eight 

fixed sites on tributaries to the lower Cowlitz River to monitor behavior and movement patterns of 

radio-tagged steelhead during the study. Mainstem fixed sites were located at the Barrier Dam, the Trout 

Hatchery and near the mouth of the Cowlitz River (rm 1; fig. 1). Tributary fixed sites were established 

on Brights Creek, Salmon Creek, Lacamas Creek, Olequa Creek, the Toutle River, at the confluence of 

Arkansas and Delameter Creeks, Ostrander Creek, and the Coweeman River (fig. 1). Fixed sites 

continuously monitored for the presence of tagged fish from June 2012 to January 2013. To supplement 

fixed site detections, we conducted three mobile tracking surveys from a boat on the mainstem Cowlitz 

River. Mobile tracking surveys were conducted on October 9, 2012, November 19, 2012, and January 9, 

2013. The first and last mobile tracking surveys included the area between the Barrier Dam boat launch 

(rm 51) and the town of Longview (rm 0. The second mobile tracking survey had limited scope because 

of hazardous weather conditions and included the area between the Barrier Dam boat launch and the 

mouth of the Toutle River (rm 20).
9

Results

Run Size, Run Timing, and River Flows

A total of 10,722 summer steelhead were captured at the hatchery during April–December 2012, 

which is the highest total since 2008. During 2008–2011, annual collection of adult summer steelhead 

averaged 6,989 fish and ranged from a low of 5,150 fish in 2009 to a high of 8,908 fish in 2010. The 

pattern of arrival timing for summer steelhead at the hatchery during 2012 was similar to trends 

observed during 2008–2011 (fig. 3). Fish began returning to the hatchery in mid-April and continued to 

be collected through December. Most fish (91 percent) were collected during June–September (fig. 3).

River flows are an important factor that can affect migration behavior of adult fish, hatchery returns, 

angler effort, and angler success. We examined river flows during 2012 and compared them to river 

flows during 2008–2011 to determine if flow conditions were typical during the study period. Average 

(daily mean) river flows in 2008–2011 were plotted against 2012 flows (fig. 4) to visually assess the 

relationship during these periods. To determine how flows differed during these periods, we calculated a 

ratio that compared 2012 flows to 2008–2011 flows. A daily flow ratio statistic was calculated for each 

date from June to November by dividing the daily flow from 2012 by the average daily flow from 2008

to 2011. For example, on July 17, 2012, flow in the lower Cowlitz River was 10,500 ft3

/s and the 2008–

2011 average flow on this date was 5,430 ft3/s. The ratio was calculated as 10,500/5,430=1.9, which

indicates that flows on July 17, 2012 were 1.9 times higher than the 2008–2011 average flow. This ratio

was plotted across the study period (fig. 4) to describe how 2012 flows varied with respect to 2008–

2011 flows. This graph shows that flows were near normal (that is, ratio of 1.0) during much of the 

study period except during July and November when 2012 flows frequently were 1.5–2.0 times higher 

than normal.
10

Figure 3. Arrival timing of adult summer steelhead at the Cowlitz Salmon Hatchery, Washington, 2008–2012.
11

Figure 4. Graphs showing daily river flows (thousand cubic feet per sec [k ft3/s]; top) measured near Mayfield Dam 

(USGS streamgage No. 14238000) during June–December 2012 (black line) and average river flows during the 

same period from 2008 to 2011 (gray line); the relationship between 2012 and average 2008–2011 flows (bottom).

Flow ratio of 1.0 indicates that 2012 flows were identical to 2008–2011 flows. Flow ratios less than 1.0 indicate that 

2012 flows were lower than 2008–2011 flows and flow ratios greater than 1.0 indicate that 2012 flows were higher 

than 2008–2011 flows.

 

River flow (ft

3/s x 1000) Flow ratio

6/1/12 8/1/12 10/1/12 12/1/12

0

5

10

15

20

25

30

35

0.0

0.5

1.0

1.5

2.0

2.5

Date
12

Hatchery Returns

One-half of the steelhead that were recycled during the study eventually returned to the hatchery 

and most of the returning fish spent 2 weeks or less in the river after being transported. A total of 549 

steelhead were recycled during the study and 273 (50 percent; table 2) of these fish were re-collected at 

the hatchery. Some of the steelhead that returned to the hatchery did not retain the Floy® tag (15 fish; 6 

percent) or the recapture date was not recorded (6 fish; 2 percent) so we could not determine residence 

time (recapture date–release date) in the lower Cowlitz River of these fish. However, most of the 

steelhead that returned to the hatchery did retain their tags and had valid return date data (252 fish; 92 

percent). The median residence time in the lower Cowlitz River for fish that returned to the hatchery 

was 9 d (days) (range = 3–105 d) and most fish (182 fish; 72 percent) returned to the hatchery within 14 

d of release. Most recycled steelhead returned to the hatchery during July and August (fig. 5) but some 

fish returned through mid-October.

Table 2. Summary of the fate of recycled steelhead that were released for a study on the Cowlitz River, 

Washington, 2012.

[Data are shown for all fish tagged during the study (including radio-tagged fish) and radio-tagged fish only]

Fate All fish Radio-tagged fish

Number of fish Number of fish

Hatchery return 273 (50 percent) 52 (48 percent)

Angler caught 102 (18 percent) 30 (28 percent)

Cowlitz River 13 (12 percent)

Mortality or regurgitated transmitter 11 (10 percent)

Not detected 3 (2 percent)

Unknown 174 (32 percent) 0

Total 549 109
13

Figure 5. Graphs showing percentage of recycled steelhead that returned to the hatchery or were caught by 

anglers (top) and run timing for summer steelhead in the Cowlitz River based on the number of fish that were 

collected at the Cowlitz Salmon Hatchery (bottom), lower Cowlitz River, Washington. Vertical dashed line denotes 

when recycling began.
14

Angler Harvest

Anglers reported harvesting 102 (18 percent; table 2) recycled steelhead during the study period.

Voluntary angler reporting accounted for the majority (90 fish; 88 percent) of the harvest data but some 

recycled steelhead were recorded in the creel survey (12 fish; 12 percent). During the creel survey,

2,947 anglers were interviewed and these anglers harvested a total of 594 summer steelhead. Recycled 

steelhead composed 2 percent of the catch during this period. Trends in angler harvest were similar to 

those observed for hatchery returns because most fish were caught during July–August (fig. 5).

However, anglers continued to catch low numbers of recycled steelhead through November (fig. 5). The 

median residence time in the lower Cowlitz River for fish harvested by anglers was 10 d (range = 1–140 

d) and most of the fish (70 fish; 65 percent) were caught within 14 d of release.

Effect of Release Timing and River Flow on Fate of Recycled Steelhead

Steelhead were assigned to one of three fates (returned to the hatchery, harvested by anglers, not 

removed from the river) for each release group to determine if there were temporal trends in the fates of 

recycled steelhead (fig. 6). For most release groups, the largest percentage of fish returned to the 

hatchery and the smallest percentage of fish were caught by anglers (fig. 6). These trends were 

consistent throughout the study period (fig. 6).

We plotted the daily number of steelhead that returned to the hatchery or were harvested by 

anglers against daily river flows from mid-June through August, when most fish were removed from the 

river, to determine if there were any apparent trends (fig. 7). The number of fish that returned to the 

hatchery each day generally increased during this period (fig. 7). Flow also appeared to affect hatchery 

returns; flows generally were decreasing on days when no fish returned to the hatchery and generally 

were increasing on the highest collection days (fig. 7). Conversely, there was no apparent temporal trend 

in angler harvest (fig. 7). River flows appeared to affect angler harvest although the relationship 

between these factors was opposite of that which was observed between river flows and hatchery 

returns; anglers generally caught more fish during days when flows were decreasing and catch numbers 

were low on days when river flows were increasing (fig. 7).
15

Figure 6. Graph showing percent of recycled steelhead from each release group that returned to the hatchery, 

were caught by anglers, or were not known to be removed from the lower Cowlitz River, Washington, 2012.

Date

6/18/12 7/2/12 7/16/12 7/30/12 8/13/12 

Percent of fish

0

20

40

60

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16

Figure 7. Graphs showing number of fish that returned to the hatchery (top graph) or were caught by anglers 

(bottom graph) each day (gray bars) and daily river flows (black line) during a study on the lower Cowlitz River , 

Washington, 2012. Data are presented from mid-June through August when most fish returned to the hatchery or 

were caught by anglers.

 

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Radiotelemetry

Radio-tagged fish provided valuable information because we were able to determine the fates of 

fish that were not removed from the river, monitor tributaries for the presence of tagged fish, and 

describe behavior patterns of fish prior to entering the hatchery or being caught by anglers. Most radiotagged fish returned to the hatchery (50 fish; 48 percent) or were caught by anglers (30 fish; 28 percent; 

table 2). The remaining radio-tagged fish (27 fish; 24 percent) were not known to have been removed 

from the river so we examined detection histories of these fish to determine their fate. Detection 

histories from fixed sites and mobile tracking events were used to determine if individual fish were 

moving within the lower Cowlitz River during October 2012–January 2013, which would indicate that a 

given fish was alive. We detected 13 (12 percent) radio-tagged fish moving within the lower Cowlitz 

River during this period. Additionally, 11 (10 percent) radio-tagged fish were detected in the lower 

Cowlitz River that did not exhibit movement during October 2012–January 2013. This detection pattern 

indicated that the fish had died, or had regurgitated the transmitter. Ten (91 percent) of these tags were 

located near popular angling areas including the Barrier Dam (1 fish), Trout Hatchery (4 fish), Mission 

Bar (2 fish), town of Toledo (2 fish), and the Interstate 5 boat launch (1 fish), which could indicate that 

tags were removed from fish or that fish died after being hooked. The remaining fish (3 fish; 2 percent) 

were never detected during the study (table 2).

Detection records show that most radio-tagged fish moved upstream from the release site and 

were detected in the river reach between the Barrier Dam and the Trout Hatchery during June–October.

In total, 89 of the radio-tagged fish (82 percent) moved upstream following release and were detected at 

the Trout Hatchery or Barrier Dam, or both. The median elapsed time from release to first detection at 

these sites was 3.7 d (range = 0.8–99.1 d). Many radio-tagged fish made repeated trips between the 

Trout Hatchery and the Barrier Dam. A single trip consisted of moving one time between the two sites.

For example, fish that moved upstream from the Trout Hatchery to the Barrier Dam and then back 

downstream to the Trout Hatchery made two trips. We determined that 32 radio-tagged fish (29 percent) 

made at least two trips between the two sites and some fish made up to six trips (fig. 8).

Radio-tagged steelhead moved downstream as the spawning period approached and were 

detected in the river reach between the Trout Hatchery and the mouth of Ostrander Creek. The last 

detection of any radio-tagged fish at the Barrier Dam occurred on November 8. Three radio-tagged fish 

were detected at the mouth of the Cowlitz River but these fish remained in the system and were later 

detected upstream during mobile tracking. During November 2012–January 2013, all radio-tagged fish 

were detected either at the Trout Hatchery site, or in the river reach between the Trout Hatchery and the 

mouth of Ostrander Creek (by mobile tracking).

We only detected one radio-tagged fish (<1 percent) on any of the tributary monitoring sites and 

this detection occurred prior to the spawning period. That fish was released on August 14 and was 

subsequently detected at the Trout Hatchery and Barrier Dam sites multiple times during August 16–26.

The fish then entered the Toutle River on August 30 and was later detected on September 7 when it 

exited the Toutle River and returned to the lower Cowlitz River. The fish was detected in the lower 

Cowlitz River near the mouth of Ostrander Creek during the October 2012 and January 2013 mobile 

tracking events.
18

Figure 8. Graph showing percentage of radio-tagged fish observed making trips between the Trout Hatchery and 

the Barrier Dam during a study on the lower Cowlitz River, Washington, 2012. Numbers above bars are the number 

of fish in each group.

Temporal Effectiveness of Opercle Punches

We measured the diameter of a total of 190 opercle punches during the study period and 

determined that the opercle punches remained open for about 30 d (fig. 9). Opercle punch measurements 

were taken at the time of tagging (63 fish) and when fish returned to the hatchery (127 fish). The 

diameter of the opercle hole was plotted against the elapsed time since tagging (fig. 9).Opercle regrowth 

generally was slow during the first 20 d following tagging, but the hole closed quickly between 20 and 

30 d after tagging. All steelhead that returned to the hatchery less than 30 d after tagging had opercle 

punches that had completely closed.

Number of trips

1 2 3 4 5 6

Percent of fish

0

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46

15

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19

Figure 9. Graph showing relationship between the inside diameter of opercle punches of adult steelhead and the 

elapsed time in days (d) since tagging for a study on the Cowlitz River, Washington, 2012.

Discussion

Our study showed that a substantial number of recycled steelhead were removed from the 

Cowlitz River shortly after they were released. We determined that 68 percent of the recycled fish 

returned to the hatchery or were caught by anglers. Nearly one-half of the recycled steelhead (252 fish; 

46 percent) were removed from the river within 14 d of release. Our results demonstrated that recycling 

summer steelhead was effective at increasing angling opportunities in the system. Anglers harvested a 

minimum of 18 percent of the fish that were recycled during the study and results from the creel survey 

showed that 2 percent of the catch during June–December consisted of recycled steelhead. However, 

approximately one-third (32 percent) of the recycled steelhead were not reported as having been 

removed from the river.

Elapsed time since tagging (d)

0 10 20 30 40 50 60 70

Diameter (mm)

0

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4

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8
20

Results from radio-tagged fish suggest that unreported harvest or mortality could partially 

explain why some recycled steelhead were not reported as having been removed from the river. We 

determined that 24 percent of the radio-tagged steelhead did not return to the hatchery or were not 

caught by anglers. However, only 12 percent of the recycled steelhead were detected in the lower 

Cowlitz River during the spawning period and no radio-tagged fish were detected in known spawning 

tributaries during November 2012–January 2013. The remaining radio-tagged fish were either not 

detected (2 percent) or were determined to have regurgitated a transmitter or died (10 percent), based on 

continued detections at a single location over a long period of time. We suspect that many of these fish 

were either harvested and not reported, or the transmitters were removed after a given fish was caught 

and either released or harvested. Mobile tracking events conducted prior to, and during, the spawning 

period provided continuous coverage throughout the lower 44 river miles in the lower Cowlitz River.

During these mobile tracking events, 91 percent of the fish (10 of 11) that were determined to have died 

or regurgitated their transmitter were located in close proximity to popular boat ramps and fishing 

locations (that is, Barrier Dam, Trout Hatchery, Mission Bar, Toledo, and Interstate 5 bridge) in the 

river. This observation would suggest that anglers contributed to this distribution because we would 

expect these transmitters to be more randomly distributed throughout the system if mortality or 

transmitter regurgitation was occurring through random chance. Given these findings, results from the 

radio-tagged fish suggest that only 12 percent of the recycled steelhead remained in the Cowlitz River 

during the spawning period. These results illustrate the value of using active transmitters within a fish

marking study because we were able to collect data on fish that were not removed from the river, which 

allowed us to better estimate the percentage of recycled steelhead that remained in the river.

Movement data from radio-tagged fish showed that most recycled steelhead moved quickly 

upstream following release and were primarily located at, or upstream of, the Trout Hatchery during 

June–October, then moved downstream and were located between the mouth of Ostrander Creek and the 

Trout Hatchery during November 2012–January 2013. Most of the recycled steelhead (82 percent) 

moved upstream and were detected at the Trout Hatchery or the Barrier Dam, or both, shortly after 

release, and the average elapsed time from release to detection in this reach was less than 4 d. Tagged 

fish that did not enter the hatchery or were not caught by anglers in this reach tended to move back and 

forth between the two sites. Nearly one-third (32 percent) of the radio-tagged fish that were detected in 

this reach made at least two trips between the sites and some fish made as many as six trips each. This 

behavior diminished over time, however, as tagged fish moved downstream when the spawning period 

approached. No radio-tagged fish were detected at the Barrier Dam after early November. Three radiotagged fish were detected at the mouth of the Cowlitz River but these fish remained in the system and 

were later detected upstream. All radio-tagged fish that were known to be alive during November 2012–

January 2013 were detected between the mouth of Ostrander Creek and the Trout Hatchery.

We focused monitoring efforts of radio-tagged fish on known spawning tributaries in the lower 

Cowlitz River because of concerns that recycled steelhead would interact, and potentially spawn, with 

wild steelhead in these areas, but findings from this study and others suggest that this did not occur.

Most of our fixed sites were located on tributaries to the lower Cowlitz River and these sites only 

detected one fish during the entire study period. The tagged fish briefly entered the Toutle River before 

returning to the Cowlitz River. None of the radio-tagged steelhead were detected in the tributaries 

during the spawning period, which suggests that recycled steelhead did not use these areas to spawn.

This observation was supported by findings from weir traps operated by WDFW on lower Cowlitz 

River tributaries. Weir traps were located on Salmon, Olequa, and Delameter Creeks, and hatchery 

summer steelhead have not been collected in these traps, although wild and hatchery winter steelhead 

have been captured there (Washington Department of Fish and Wildlife, unpub. data, 2012). Based on 
21

these findings, summer steelhead apparently are not using, or spawning in, lower Cowlitz River 

tributaries. Given these observations and the documented use of the mainstem Cowlitz River by 

recycled steelhead during November 2012–January 2013, future evaluations should be considered that 

focus more intensely on summer steelhead behavior patterns between the Trout Hatchery and Ostrander 

Creek. Increased monitoring in this reach may provide useful information regarding behavior patterns 

during the spawning period and also could be insightful for estimating unreported harvest of recycled 

fish.

Abnormally high flows occurred during early July and November–December 2012 and these are 

important periods for summer steelhead in the Cowlitz River so results from this study may have been 

affected. Hatchery returns and angler catch were affected by river flows. Hatchery returns increased and 

angler catch decreased during periods of increasing river flow and these trends were reversed when river 

flows were decreasing. Hatchery returns and angler harvest of summer steelhead typically peaks during 

July so the abnormally high flows measured during July could have influenced findings of the study.

High July flows during 2012 may have resulted in higher than normal hatchery returns and lower than 

normal angler catch, when compared with normal flow periods. Hatchery summer steelhead in the 

Cowlitz River typically spawn during December so the higher than normal November–December flows 

could have influenced the fish distribution during this time. Radio-tagged fish were all located between 

the Trout Hatchery and the mouth of Ostrander Creek and it is possible that these fish were responding 

to the high flows, rather than targeting a specific river reach.

Finally, we were able to collect data on the retention time of opercle punches and our results 

suggest that this marking technique may be effective for about 30 d under the conditions we observed.

We found that regrowth rates were relatively slow within about 21 d of the marking event. However, 

every fish that was recovered at the hatchery more than 30 d after tagging had opercle punches that were 

completely closed. These marks remained visible after tissue regrowth, but it is unclear how long this 

would remain true. Our results suggest that opercle punches should be considered short-term marking 

techniques until additional studies have been conducted to evaluate their effectiveness.

Acknowledgments

This research was funded by the Washington Department of Fish and Wildlife. Transportation of 

tagged fish from the hatchery to the release site was conducted by Tacoma Power. We are grateful to 

Mike Blankenship, Teresa Fryer, John Serl, and Wade Heimbigner with the Washington Department of 

Fish and Wildlife and the Pacific States Marine Fisheries Commission for their contributions during the 

study. Similarly, Missy Baier, Ross Reichert, and Tony Royce with Tacoma Power provided assistance 

with fish collection and handling at the Cowlitz Salmon Hatchery. Reviews by Mark Johnson, Bjorn 

Van-der-leeuw, and Brady Allen greatly improved this report.
22

References Cited

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management: Environmental Biology of Fishes, v. 94, p. 21–28.

National Marine Fisheries Service, 2011, 5-year review—Summary and evaluation of lower Columbia 

River Chinook, Columbia River chum, lower Columbia River coho and lower Columbia River 

steelhead: July 26, 2011, NMFS-NWFSC Status Review Update Memo.

Rand, P.S., Berejikian, B.A., Pearsons, T.N., and Noakes, D.L.G., 2012, Ecological interactions 

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Waples, R.S., 1991, Dispelling some myths about hatcheries: Fisheries, v. 24, p. 12–21.
Publishing support provided by the U.S. Geological Survey

Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the 

Director, Western Fisheries Research Center

U.S. Geological Survey

6505 NE 65th Street

Seattle, WA 98115

http://wfrc.usgs.gov/
Kock and others—Behavior and Movement of Adult Summer Steelhead Following Collection and Release, Lower Cowlitz River, Washington, 2012–2013—Open-File Report 2013–1116