10
BRT SUMMARY OF BIOLOGICAL INFORMATION

Environmental Features

The Columbia River is the third largest river in North
America and drains an area of approximately 668,000 km?. This
area includes British Columbia, Idaho, Washington, Montana, and
Oregon, and smaller sections of Wyoming, Nevada, and Utah. It
flows through or borders on three physiographic regions of the - +
Pacific Northwest: the Rocky Mountain System, the Intermontane
Plateau, and the Pacific Mountain System (Scott et al. 1989).

Originating in Lake Windermere, B.C. in the northern Rocky

Mountains, the Columbia River flows through British Columbia for
over 1,000 km before entering the United States via the Okanogan
Highlands. The river flows westerly until it ‘turns south,
approximately at its confluence with the Okanogan River

(RKm 859), where it forms a boundary between two distinct
ecoregions: the Columbia River Basin (part of the Intermontane
Plateau) on the east, and the Cascade Mountains (part of the
Pacific Mountain System) on the west. Approximately 25 km below i
its confluence with the Snake River (RKm 522), the Columbia River
turns westerly towards the Pacific Ocean. For the purposes of
this Biological Status Review, the MCR is defined as the mainstem
river and tributaries between McNary Dam (Rkm 470) and Chief

Joseph Dam (Rkm 878; Fig. 1). This definition was previously

used by Mullan et al. (1992b) and Chapman et al. (1994).
The western side of the MCR is generally mesic, alpine

habitat. Rivers originating there drain the eastern slopes of



31
populations of MCR chinook salmon were founded with many
individuals originally from regions hundreds of kilometers
upstream from the tributaries they now inhabit.

Portions of MCR late-run chinook palmon have been mixed
considerably over the past two to three decades. This mixing was
due to the variety of methods employed to collect broodstock at
dams, hatcheries, or other areas and as a result of juvenile
outplantings into various areas, including the petitioned streams
(reviewed in Chapman et al. 1994). Since 1967, as many as 20% of
summer-run chinook salmon broodstock for Wells Hatchery
operations have been collected from the late component (so called
fall-run) of ocean-type fish passing over Wells Dam after the
nominal cutoff date (28 August) between summer- and fall-run
groups (Allen 1966, 1967; Allen et al. 1971; Chapman et al.
1994). Moreover, recoveries of coded-wire-tagged adults from
various juvenile releases in the late 1970s and 1980s indicated
that wild and hatchery summer-run fish originating above Rock
Island Dam have spawned extensively with designated fall-run fish
originating in the Hanford Reach and Priest Rapids Hatchery
(Chapman et al. 1994).

Conversely, about 15% of the so-called fall chinook salmon
emigrating from spawning beds below Priest Rapids Dam have
returned to spawn in the Columbia River system above Wells Dam

{Chapman et al. 1994). The possibility of substantial genetic

exchange between chinook salmon populations above and below Rock

Island Dam was noted almost half a century ago (Fish and Hanavan



27
"June hogs"

Many residents of the Pacific Northwest are aware of stories
alleging that a specific run of particularly large chinook
salmon, the so-called "June hogs," once migrated up the Columbia
River (e.g., Seufert 1980). These fish, said to have averaged
18-45 kg in weight; supposedly predominated the middle portion of
the run passing through the lower river and migrated to spawn
somewhere in the Columbia River Basin. Most assumed that June
hogs were summer-run fish.

However, Seufert (1980, p. 9), referred to them as "huge
spring chinook," which would indicate stream-type chinook salmon.
In addition, early settlers observed chinook salmon spawning as
early as August in the upper Columbia River in British Columbia
(Bryant and Parkhurst 1950), a life history pattern
characteristic of stream-type chinook salmon in the Columbia
River Basin. By comparison, all observed populations of upper
Fraser River chinook salmon have stream-type juvenile life
histories (Taylor 1989).

Regarding latitude, altitude, climate, and geography, the
upper Columbia River is similar to the upper Fraser River and is
more distant from the ocean. Therefore, it is logical that the
life histories of chinook salmon populations in the two systems
would be similar as well. In fact, after deglaciation, the
Columbia River appears to have been the principal source for the
repopulation of Fraser River fish fauna in general (McPhail and
Lindsey 1986) and chinook saimon in particular (Utter et al.

1989).





36
Table 2. Continued.

Year of Number
Stock* Hatchery” Agency* Class Plant Stream* Planted
Wells WELLS WDF yearling 88 Columbia R. 582,223
Wells WELLS WDF fingerling 88 Columbia R. 1,562,710
Wells WELLS WDF yearling 89 Columbia R. 429,042 t
Wells WELLS WDF fingerling 89 Columbia R. 1,781,788
Wells WELLS WDF fry 89 Columbia R. 386,269
Wells WELLS WDF yearling 90 Columbia R. 602,118
Wells WELLS WDF fingerling 90 Columbia R. 1,310,656
Wells WELLS: WDF yearling 91 Columbia R. 436,024
Wells WE11S WDF fingerling 91 Columbia R. 329,669-
Wells WE11S WDF yearling 92 Columbia R. 371,000 ‘
Wells WE11S WDF fingerling 92 Columbia R. 630,000
Wells WElls WDF yearling 92 Columbia R. 302,000
Wells WE11S WDF yearling 93 Columbia R. ___ 392,000

Total = 54,653,496

Columbia River plants - Fall chinook salmon

Priest PRIEST WDF fingerling 64 Columbia R. 1,073,800
Priest PRIEST WDF fingerling 65 Columbia R. 349,000
Priest PRIEST WDF fingerling 66 Columbia R. 1,177,000
Priest PRIEST WDF fingerling 67 Columbia R. 1,470,000
Priest PRIEST WDF fingerling 68 Columbia R. 7,141,000
Priest PRIEST WDF fingerling 69 Columbia R. 2,990,500
Priest PRIEST WDF fingerling 70 Columbia R. 1,995,300
Priest PRIEST WDF fingerling 71 Columbia R. 1,804,200
Wells WELLS WDF yearling 71 Columbia R. 359,000
Wells WELLS WDF fry 71 Columbia R. 1,425,000
Priest PRIEST WDF fingerling 72 Columbia R. 2,853,698
Priest PRIEST WDF fingerling 73 Columbia R. 660,128
Priest PRIEST WDF fingerling 74 Columbia R. 2,913,587
Priest PRIEST WDF fingerling 75 Columbia R. 1,285,508
Simpson WELLS WDF fingerling 75 Columbia R. 673,250
Simpson ROCK R WDF yearling 75 Columbia R. 41,639
Priest PRIEST WDF fingerling 76 Columbia R. 1,888,277
Priest PRIEST WDF fingerling 77 Columbia R. 1,226,061
Priest PRIEST WDF fingerling 78 Columbia R. 1,460,606 t
unknown RING WDF fingerling 78 Columbia R. 497,806
Priest PRIEST WDF fingerling 79 Columbia R. 1,199,988
Priest RING WDF yearling 79 Columbia R. (RG) 275,000
Col. R. PRIEST WDF fingerling 80 Columbia R. 2,383,690
Priest RING WDF fingerling 80 Columbia R. (RG) 668,800
Elokomin ROCK R WDF yearling 81 Columbia R. 296,127 ¢
Col. R. PRIEST WDF fingerling 81 Columbia R. 946,408
Priest PRIEST WDF fingerling 81 ~° Columbia R. 2, 237,970
Bonn PRIEST WDF fingerling 81 Columbia R. 1,635,006
Bonn RING WDF yearling B2 Sprng. Cr. 788,000
Priest PRIEST WDF fingerling 82 Columbia R. 3,821,932
Bonn PRIEST WDF fingerling 82 Columbia R. 1,687,309
Bonn ROCK R WDF fingerling 83 Columbia R. 871,900 >
Bonn SPRING FWS fingerling 983 Columbia R.(V) 640,857
Priest PRIEST WDF fingerling 83 Columbia R. 4,245,000
Bonn PRIEST WDF fingerling 83 Columbia R. 6,051,700



4
native ecosystems. Implicit in this approach is the recognition
that hatcheries are not a substitute for natural ecosystems.

The decision to focus on natural fish is based entirely on
ecosystem considerations; the question of the relative merits of
hatchery vs. natural fish is a separate issue. Fish are not
automatically excluded from ESA consideration because some of
their direct ancestors were reared in a hatchery. Conversely,
identifying a group of fish as "natural" as defined here does not
necessarily mean that they are part of a listed ESU. Fora
discussion of artificial propagation of Pacific salmon under the

ESA, see Hard et al. (1992).
Thresholds for Threatened or Endangered Status

The ESA (sec. 3) defines the term "endangeréd species" as
“any species which is in danger of extinction throughout all or a
significant portion of its range." The term "threatened species"
is defined as "any species which is likely to become an
endangered species within the foreseeable future throughout all
or a significant portion of its range." Neither NMFS nor the
U.S. Fish and Wildlife Service (USFWS), which share authority for

administering the ESA, has an official policy regarding

thresholds for considering ESA "species" as threatened or

endangered. An information document on this topic published by
NMFS suggests that conventional rules of thumb, analytical
approaches, and simulations may all be useful in making this
determination (Thompson 1991). There is considerable interest in

incorporating the concepts of population viability analysis (PVA)



64
for several reasons, it is unlikely that any appreciable remnants
of this gene pool remain in the petitioned streams.

First, reports of spawn timing by early settlers suggested
stream-type, not ocean-type fish. Comparison with upriver
populations from the Fraser River, which has headwaters near
those of the upper Columbia River, also suggests that the upper
Columbia River chinook salmon may have been stream-type fish.
Thus, it is uncertain what relationship the ocean-type fish
currently residing in the mid-Columbia River have to the original
upriver populations.

Second, it is likely that "June hogs" taken in the lower
Columbia River were comprised of large fish from many different
populations. There are conflicting accounts from the 1800s
regarding the size of chinook salmon in the upper Columbia River.
For example, historical accounts from the early 1800s suggest
that chinook salmon taken by aboriginals at Kettle Falls in the
upper Columbia River averaged only 7 kg in weight (Mullan et al.
1992b), whereas Bryant and Parkhurst (1950) reported that early
settlers witnessed fish averaging 18 kg. In any case, by the
time the GCFMP was initiated, wild adult ocean-type fish taken at
Rock Island Dam averaged only about 8 kg (Fulton and Pearson
1981). Thus, even if a run of large fish did occur historically
in the upper Columbia River, it no longer existed by 1939. "June
hogs" from all populations may have been largely eliminated by
the turn of the century as a result of heavy fishing pressure.

Third, adults collected for the GCFMP were a mixture of

summer- and fall-run fish from all areas above Rock Island Dam.



46

The same general pattern was seen in the dendrogram based on
Cavalli-Sforza and Edwards (1967) chord distance (Fig. 3): the
clearest distinction was between the stream-type and ocean-type
fish. This analysis differs from Nei’s (1978) in that Yakima
River ocean-type fish aligned more closely to Hanford
Reach/Priest Rapids stocks than to Bonneville Hatchery fish, and
Deschutes River fish aligned with Lyons Ferry Hatchery/Marion
Drain fish rather than with fish from the Little White Salmon
Hatchery. Nei’s unbiased distance measure (Nei 1978) adjusts for
increased genetic similarity due to small sample sizes, whereas
Cavalli-Sforza and Edwards’ (1967) distance metric does not.
However, as in Nei’s dendrogram, MCR samples formed a distinct
group in which summer- and fall-run samples clustered with one
another. In these dendrograms, we included a sample from the
Sandy River, which feeds into the lower Columbia River below
Bonneville Dam, to provide an indication of the level of
divergence between fall chinook salmon from the lower and middle
reaches of the Columbia River.

The close genetic relationship among the late-run MCR

samples was also seen in pair-wise G-tests comparing frequencies

t
of polymorphic loci among samples. Marshall (1993) reported that
all the "summer-run" samples shared a high degree of genetic
similarity (i.e., samples from the Wenatchee River, Wells ‘

Hatchery, and the Similkameen River were not significantly
different (P > 0.05)). Further, the Priest Rapids Hatchery
sample of fall-run fish was not significantly different from the

Hanford Reach (fall-run), Wells Hatchery (summer-run), or



44

Genetic Characteristics

To evaluate chinook salmon populations in the Snake River,
Matthews and Waples (1991) compiled a 21-locus allozymic (protein
electrophoretic) data set for 44 samples within the Columbia
River Basin. This analysis used relatively few loci to allow
inclusion of samples dating back to 1980. Three major groups
were identified: 1) fall-run and MCR summer-run fish;

2) Willamette River populations; and 3) spring-run and Snake
River summer-run fish. Because summer- and spring-run fish from
the Snake River were genetically similar and shared similar life
histories, they were considered a single species as defined by
the ESA.

Marshall (1993, 1994a and b) examined a 36-locus data set
for chinook salmon which included data for several new
populations in the MCR and which used only recent samples
(Appendix). This data set provided a more comprehensive view of
the pattern of genetic differentiation among MCR populations than
the data set described by Matthews and Waples (1991). Marshall
(1994a and b) provided dendrograms based on cluster analyses of
two common genetic distance measures.

The dendrogram based on Nei’s (1978) genetic distance
produced results similar to those found by Matthews and Waples
(1991). A clear separation between ocean- and stream-type fish
in the Columbia River Basin was observed (Fig. 2). Notably,
after correcting for sampling error, genetic distances between

fall- and summer-run fish from the MCR were essentially zero.



50
evaluations considered recent, published assessments of the
status of chinook salmon stocks within the petitioned area by
agencies or conservation groups (Nehlsen et al. 1991, WDF et al.
1993). These assessments are summarized in Table 4. Nehlsen
et al. (1991) considered summer chinook salmon to be of "special
concern" in the Okanogan River and at "moderate risk of
extinction" in the Methow River. Summer chinook salmon in the
Entiat River and spring chinook salmon in the Okanogan River were
considered to be extinct. No other chinook salmon populations in
the MCR were reported at risk. Washington Department of
Fisheries (WDF et al. 1993) considered summer chinook salmon in
the Okanogan and Methow Rivers to be "depressed" but rated all
other existing summer and fall chinook salmon stocks in this
region as "healthy."

Quantitative assessments were based on time series of adult
counts at Columbia River dams and redd counts in the tributary
rivers. However, counts from lower Columbia River dams provided
little direct information about MCR ocean-type fish. First,
these counts included summer-run chinook salmon from the Snake
River. Second, there is abundant evidence that inflexible cutoff
dates between spring-, summer-, and fall-run chinook salmon can
lead to erroneous conclusions based on dam counts alone,
particularly in years with unusual environmental and oceanic
conditions, as discussed above. This second caveat also applies
to attempts to separately enumerate summer- and fall-run chinook
salmon at upriver dams. Therefore, we evaluated passage of

summer- and fall-run chinook salmon as a single unit.



54

Table 5. Summary of recent 5-year average (1989-93) and percent.
annual change of ocean-type chinook salmon redd counts
(expanded aerial counts) in the Columbia River Basin
above Rock Island Dam (RIS). Percent annual change is
based on exponential regression of passage counts
against time for two time periods: the entire data
series (1956-93), and the most recent 20 years
(1974-93). Based on data from Chapman et al. (1994;
appendix D-2).

Average —Percent annual change _
Location redd count Full series Last 20 years
Similkameen 191 +2.8 -0.3
Okanogan 112 -O.1 -3.1
Methow 202 -2.9 -6.4
Wenatchee 2,530 41.5 +1.6
Total above RIS* 3,064 +0.5 +0.3

* Includes a small number of redds counted in the Entiat River,
the Chelan River, and the Columbia River between Rocky Reach
Dam and Wells Dam.



42

Table 3. Rearing facilities for chinook salmon in the mid-
Columbia River operated by the U.S. Fish and Wildlife
Service (USFWS) and Washington Department of Fisheries
(WDF). Modified from Chapman et al. (1994).

Years*

Facility Agency River
Leavenworth NFH USFWS 1941-present Wenatchee ;
Entiat NFH USFWS 1941-1964 Entiat
Winthrop NFH USFWS 1942-1983 Methow
Priest Rapids WDF 1963-present mid-Columbia ‘
Rocky Reach WDF 1974-present mid-Columbia
Wells WDF 1967-present mid-Columbia
Eastbank WDF 1990-pesent Wenatchee
acclimation ponds WDF 1990-present Methow
acclimation ponds WDF 1990-present _ Okanogan

* Years when ocean-type chinook salmon were reared.
NFH = National Fish Hatchery.

a



14

By the turn of the century, sawmill, hydroelectric, and
irrigation dams had already decimated salmon populations in this
area. Since then, the condition of spawning habitat has improved
greatly (Mullan et al. 1992b). The small dams on tributaries
have been removed, irrigation diversions have been screened, and
riprap has been placed over eroded stream banks, providing
critical summer and winter habitat for juveniles (Chapman 1989).
Mullan et al. (1992b) concluded that, with the exception of the
Yakima River, degradation of habitat in MCR tributaries does not
appear to be a significant cause of run depression. In fact,
these authors consider that the area covered by the petition is
currently at or near maximum historical smolt production for
chinook salmon.

The Yakima River differs somewhat from othe MCR
tributaries. At its headwaters, the streams are steep and drain
mountains about 1,500 to 3,000 m in elevation. The river valleys
then flatten out and meander down gentle slopes into the Columbia
River. As previously mentioned, the overall bioproductivity of
the Yakima River is higher than that of other MCR streams because
of agricultural runoff and lake and reservoir storage. However,
these factors may also lead to increased water temperature, which
inhibits salmonid migration and spawning (Mullan et al. 1992b).

Production of late-run chinook salmon in the Yakima River
has also been severely curtailed by unrestrained irrigation
practices. These practices include the use of unscreened
irrigation diversions and exploitation of river water to an

extent that produces -low flows, which diminish summer habitat



32
1948). Attempts to maintain discrete hatchery stocks have only
recently been initiated.
The Yakima River has been heavily planted with Bonneville
Hatchery ocean-type chinook salmon (Table 2), which are said to

stray at substantial rates (Busack 1990, WDF et al. 1993).

Stock Histories

Since settlement of the Columbia River Basin in the mid-
nineteenth century, a variety of activities associated with
development and commerce have had negative consequences for
Columbia River salmonid populations. The list of harmful
activities includes prodigious overharvest of salmon; destructive
or unregulated land management practices, including timber
harvest, mining, livestock grazing, and irrigation; and
construction of hydroelectric facilities with absent or
inadequate adult and juvenile fish Passage facilities.

High harvest rates continue today, primarily by fisheries in
the northern ocean ranges of Columbia River salmonids (Howell
et al. 1985). According to estimates, it may take scores of
years for riparian habitat destroyed by logging to recover
(Sedell and Swanson 1984). Livestock grazing continues to
degrade stream habitats (Platts 1991). Recent examinations of
screens at Columbia River irrigation diversions reveal that many
screening devices need modernization (WDF et al. 1990).

Yet, in spite of historic and contemporary human activities
adversely affecting Columbia River salmonids, the number of
ocean-type chinook salmon returning to mid-Columbia River

spawning areas has increased substantially since the construction



|

63
are closely related to spring chinook salmon in both rivers while
MCR summer chinook salmon are closely related to fall chinook

salmon in both rivers.

Spawn and Run Timing }

Although groups of fish returning over dams in the MCR were

once thought to spawn in different habitats at different times,
this notion has not been supported by the data collected for this
Biological Status Review. Both types of fish were found to spawn
in tributaries as well as mainstem areas, with substantial

overlap in the spawn timing and duration.

Evolutionary Significance

The petitioners argue that summer-run chinook salmon in the
Methow and Wenatchee Rivers are the last remnants of the large
population of summer-run fish that once spawned in areas above
Grand Coulee Dam. The summer run of fish in the Columbia River
was renowned for its large size (hence the term "June hogs") and
abundance. Additionally, the petitioners argue that the Okanogan
River, which did not receive transplants from the GCFMP, contains
the "only documented native stock of summer chinook in the

mid-Columbia basin" (NEDC et al. 1993. p. 6).

Phenotypic and Life History Traits

Given their extensive upriver migration and presumably
distinctive habitat characteristics, it seems likely that chinook
salmon spawning in the now inaccessible Lake Windermere region of

the upper Columbia River historically comprised an ESU. However,



iii

CONTENTS

Summary .
Acknowledgments .
Introduction ...

Key Questions in ESA Evaluations rs
The "Species" Question... eee ee ee
Hatchery Fish and Natural Fish : .
Thresholds for Threatened or Endangered Status .

Summary of Petitioners’ Claims rs
Reproductive Isolation. ...........

Geographic Isolation .. wee eee
Distinctive Life History and
Body Size Characteristics
Evolutionary Significance
Population Trends . Hee ee ee

BRT Summary of Biological Information woe ee
Environmental Features . . se ee ee
Life History Characteristics cee eee

Juvenile Life History Characters”

Run and Spawn Timing .. .
Age at Spawning, Sex Ratio, and Fecundity :
Ocean Distribution a

Juvenile Behavior ........
"June hogs"... .. 2... 0.
Straying ............ :

Stock Histories

Grand Coulee Fish Maintenance Project, “1939- 43"

Artificial Propagation ... .
Phenotypic Characteristics ........
Genetic Characteristics .

Population Abundance and Threshold Evaluations
Historic Abundance Estimates and Trends .. .
Present Abundance Estimates and Trends... .

Discussion and Conclusions ....... os
Reproductive Isolation .

Genetic Characters . .

Phenotypic Characters .

Life History Characters

Spawn and Run Timing
Evolutionary Significance .

Phenotypic and Life History Traits

Genetic Data ... . . se eee
Conclusion: Species Determination |] | sone
Threshold Determination .........0.

Comments 2... . 2... eee

Citations .

Appendix: Protein’ Loci and Sample Information for

Genetic Analyses .... ee eee

vii

my

Woo ANHARWNHND



Hatchery; there is no indication that the Okanogan stock is

representative of a remnant upstream chinook salmon stock.

Conclusion: Species Determination

Genetic and life-history information, as well as data from
various tagging experiments, all fail to demonstrate reproductive
isolation between summer- and fall-run chinook salmon in the mid-
Columbia River (Table 7). In addition, coded wire tag data
suggest that the two forms have a similar ocean distribution.
Therefore, we concluded that all late-run, ocean-type chinook
salmon from the mid-Columbia River are part of the same ESU as
defined by the ESA.

We evaluated the relationship of this ESU to three other
groups of Columbia River Basin chinook salmon and found
substantial genetic and life-history differences: 1) stream-
type, spring chinook salmon from the mid-Columbia River were
clearly part of a separate ESU; 2) Snake River summer chinook
salmon were much more closely related to Snake River spring
chinook salmon than to summer chinook salmon from the mid-
Columbia River; and 3) the closest relatives of mid-Columbia
River late-run chinook salmon are other groups of Columbia River
fall chinook salmon.

Two major types of fall chinook salmon were found in the
basin: “tules" and "upriver brights." Substantial genetic
differences have been demonstrated between these two types of

chinook salmon in the Columbia River. The "upriver bright" group

“includes late-run chinook salmon from the mid-Columbia River as

well as Snake River fall chinook salmon.



es |
65

It seems likely, therefore, that genetic admixture, in addition
to translocation, has occurred in existing summer-run chinook

salmon from the mid-Columbia River. Nevertheless, abundance of f
chinook salmon increased at least temporarily in rivers that

received transplants from the GCFMP, so presumably some genes
from upriver stocks were incorporated into mid-Columbia River
populations. Whether any genetic traits that distinctly }
characterized upper Columbia River chinook salmon still exist in

the MCR is not known with certainty, but we found no empirical I

evidence to support this hypothesis.

Finally, although the Okanogan River is the only major

stream in the petitioned area that did not receive transplants
from the GCFMP, it is unlikely that summer-run fish in this river
represent an essentially pure native stock. All late-run (summer
and fall) chinook salmon adults reaching Rock Island Dam were
taken for the GCFMP for a period of 5 years. According to age
data for late-run chinook salmon from the mid-Columbia River,
less than 1% of returning adults are older than 5 years.
Therefore, the current population in the Okanogan River, which is
upstream from Rock Island Dam, must be derived largely, if not
entirely, from recolonization with manipulated populations of the

GCFMP.

Genetic Data
Several published genetic studies and new data from WDF
presented here have shown a strong genetic similarity between

summer-run fish from the Wenatchee and Okanogan Rivers and Wells



Comments

While we do not believe that this ESU is at significant risk
of extinction or endangerment, the low numbers of ocean-type
chinook salmon above Rocky Reach Dam {including the Methow and
Okanogan Rivers), despite the virtual elimination of inriver
harvest on these stocks, are of concern. Declines since the mid-
1970s in this region may simply be a return of the populations to
normal carrying capacity following substantial hatchery
supplementation, or may indicate local problems with habitat, dam
passage, or hatchery practices. Special management consideration
of these particular stocks may be warranted.

Some aspects of artificial propagation also pose risks for
populations within the ESU. For example, there have’ been large
releases of fall chinook salmon in the mainstem Columbia River
and in the Yakima River in recent years. We do not believe that
the potential genetic and ecological consequences of these

releases have been adequately addressed.

SS aaa

Sea

=

See



25
catch distribution than MCR "fall-run" salmon (Waples et al.
1991). On the other hand, similar, but more limited, data showed
virtually no difference in the oceanic distributions of MCR
ocean-type fish released from Wells Dam ("summer-run") and Priest

Rapids ("fall-run") hatcheries (Howell et al. 1985).

Juvenile Behavior

Timing of fry emergence has not been well documented for
naturally produced ocean-type fish. In the MCR, fry emerge
primarily in April and May (Chapman et al. 1994). At the Wells
Dam spawning channel (summer-run fish), fry emerged from January
through April during 1968-71 (Howell et al. 1985). For the
1963-67 broods at the Priest Rapids Hatchery spawning channel,
emergence occurred primarily in late April and early May (Howell
et al. 1985).

Typically, chinook salmon fry move downstream after
emergence. For many populations of ocean-type fish, fry may
continue migrating to the estuary or take up residence in the
river for a few weeks to a year or more before entering the ocean
(Healey 1991). In. the Columbia River Basin and its tributaries,
all ocean-type fry leave redd areas a few days to weeks after
emergence (Chapman et al. 1994). Some fry rear only a short
distance from nursery areas before migrating, while others may
migrate downstream a considerable distance to rear. Although
the exact mechanisms controlling dispersal behavior are largely
unknown, they are probably related to a variety of factors such
as inter- and intraspecific social interactions (Reimers 1968,

Taylor 1988), habitat availability (Lister and Walker 1966), and



11

Rocky Reach Dam
= Wenatchee

McNary Dam OREGON

t

al,
0 10 20 miles N

Figure 1. Map of mid-Columbia River Basin, showing principal
tributaries and hydroelectric facilities.



17

In North America, the Columbia River is located near the
middle latitudes of the chinook salmon range. The Columbia River
is inhabited by populations with high diversity in juvenile
migrational behavior and timing: both stream- and ocean-type
populations inhabit the basin. As in areas outside the Columbia
River, stream temperatures, which vary with elevation, appear to
control the distribution of the two types. Mainstem areas and
lower tributary streams of the Columbia and Snake Rivers produce
only ocean-type juveniles, and upper tributaries of the Columbia
and Snake Rivers produce only stream-type juveniles.

However, some tributaries, including the MCR streams listed
in the petition, produce both types. In both the mid-Columbia
and Snake Rivers, spring-run chinook salmon produce stream-type
juveniles, and fall-run chinook salmon produce o¢ean-type
juveniles. However, the so-called "summer-run" adults produce
ocean-type juveniles in the MCR above McNary Dam and stream-type
juveniles in the Snake River.

In summary, available life history information indicates a
strong affinity between fish designated as summer- and fall-run
in the MCR, and between spring- and summer-run fish in the Snake
River (Matthews and Waples 1991). For example, ocean-type
chinook salmon in the mainstem Yakima River exhibit life-history
and spawning characteristics similar to those of ocean-type fish
in the Hanford Reach of the Columbia River. Genetic data
(discussed below) also support the hypothesis that these

affinities correspond to ancestral relationships.



13

Table 1. Habitat characteristics of the mid-Columbia River Basin
and tributaries inhabited by ocean-type chinook salmon
(from Bryant and Parkhurst 1950; Davidson 1953; CBIC
1957; Mullan et al. 1992b; Chapman et al. 1994).

River: Okanogan Methow Chelan Entiat Wenatchee Yakima Columbia
Location 859 843 810 779 7154 540 470-
(RKm) 878
Gradient low steep/ low steep/ steep/ med./ low
low low low low
Terrain grass alpine/ grass alpine/ alpine/ alpine/ grass
grass grass grass grass
Runoff snow/ snow/ reser- snow/ snow/ reser- reser-
lakes rain voir rain rain voir voir
Minimum -* 13.9 n/a 3.5 19.8 36.8 2405
flow (m?/s)
Climate arid wet/ arid wet/ wet/ wet/ arid
arid arid arid arid |
Productivity med. low low low low high low/
med.
Temperature low/ low/ med. low/ low/ xmed./ med. /
high high high high high high

* Dash indicates data not available.
P At Rock Island Dam.



26
river discharge (Healey 1991). Chapman et al. (1994) summarized
results of several recent studies that suggest fish size or
growth may be important variables regulating downstream
movements.

Subyearling, ocean-type chinook salmon in the Columbia River
tend to migrate downstream slowly, foraging and growing as they
move seaward. These fish move out of rearing areas in late
spring or early summer, with the majority passing downstream
through McNary Dam from mid-July through mid-September. Fish
originating from upstream areas migrate about 2-3 weeks later
than those from downstream areas (Chapman et al. 1994).
Impoundment of the river has likely shifted the migrational
timings of these fish later than during predevelopment times
(Park 1969). This later passage has apparently increased the
proportion of fish that remain in the Columbia River over winter
(Chapman et al. 1994).

Subyearling chinook salmon migrants use estuaries
extensively for rearing prior to ocean entry (Healey 1991). In
the Columbia River, estuarine residence times vary greatly from a
few days to several months or longer. Rich (1920) recorded
subyearling chinook in the estuary in all months, with some

staying over winter.



8

Distinctive Life History and Body Size Characteristics

Time of peak spawning--The petitioners state that MCR summer
chinook are distinct because peak spawning occurs during the last
2 weeks in October and continues through November (NEDC et al.
1993, p. 7 and 10).

Age and body size at spawning--The petitioners claimed that
MCR summer chinook were referred to as "June hogs" because of
their time of migration and size (NEDC et al. 1993, p. 1-2).
They claimed that the age at spawning of MCR summer chinook
ranges from 2 to 6 years, with 4- and 5-year-old fish making up
nearly 80% of the spawning run (NEDC et al. 1993, p. 10). They
also claimed that the size range for 4- and 5-year-old fish
varied from 78 to 89 cm {(NEDC et al. 1993, p. 10).

Smolt age--The petitioners stated that the largest number of
MCR summer chinook juveniles emigrate seaward as subyearlings in
mid-to-late summer (NEDC et al. 1993, p. 10).

Effects of hatchery fish--The petitioners stated that the
Wells Hatchery has recently been contaminating the summer
chinook salmon stock with fall chinook salmon, and that this
intermixing has changed inriver migration times of chinook
salmon in the MCR (NEDC et al. 1993, p. 7). However, they also
assert that introgression of hatchery fish with natural MCR
summer chinook has been slight in the MCR Basin, and they

estimate that 65% of the summer chinook are "natural" (NEDC
et al. 1993, p. 8).

fi



Appendix--Continued.

80

Run Years
Sample type sampled Comments
Deschutes River fall 1990-92 Oregon
John Day River spring 1990-92
Round Butte Hatchery spring 1990 Deschutes River Basin,

Oregon

a


67

Previously, ecological, genetic, and ocean distribution data
were used to demonstrate that Snake River fall chinook salmon are
distinct from mid-Columbia River fall chinook salmon and
represent a separate ESU. Therefore, we concluded that late-run
(summer and fall), ocean-type chinook salmon from the mid-
Columbia River represent an ESU separate from all other chinook
salmon in the Columbia River Basin. Some of the distinctive

habitat features of this ESU are discussed above.

Threshold Determination

Dam and redd count information indicated that although
depression in some individual runs of late-run chinook salmon in
the mid-Columbia River is cause for concern, the mid-Columbia
River late-run, ocean-type chinook salmon ESU as a whole is
relatively healthy, with little risk of extinction in the
foreseeable future. Even if we considered populations from only
those rivers identified in the petition (Okanogan including
Similkameen, Methow, and Wenatchee), we would find little risk of
extinction for those populations.

While redd counts in two of these rivers (Okanogan and
Methow) have exhibited substantial declines since the late 1960s,
they have been relatively stable since 1980, and counts in both
the Wenatchee and Similkameen Rivers have exhibited long-term
(1956-93) increasing trends. Based on Rock Island Dam adult
counts, this group of populations is certainly more abundant than

it was in the 1930s and 1940s.


52

The petitioners provided only selected information about
escapement in the MCR, and we consulted other sources to provide
a more complete picture. Redd counts (including both summer- and
fall-run fish) for the Wenatchee, Methow, Okanogan, and
Similkameen Rivers all show large fluctuations, with very low
points in the early 1980s (Fig. 4). Since that time, Wenatchee
River redd counts have shown a substantial increase, while those
for the other three rivers have shown no discernible trend. Over
the entire available data series (1956-93), only the Methow River
redd counts show a substantial downward trend (Table 5), although
both the Methow and Okanogan River counts are substantially below
peak counts from the late 1960s and early 1970s. Both the
Similkameen and Wenatchee River counts show substantial upward
trends over the full data series.

Historic counts of adult salmon ascending fish ladders at
dams provide additional assessment of population abundance and
trends. The longest record for the mid-Columbia River is from
Rock Island Dam. Because of its location, counts from Rock
Island Dam provide an index primarily of the petitioned stocks,
not of the entire ESU. Counts of adult late-run ocean-type
chinook salmon at this dam (Fig. 5) showed a decline in the late
1930s, followed by a substantial increase during the 1940s and
1950s. Since the late 1950s, abundance has fluctuated over about
a three-fold range with no substantial trend. However, over this
period, the summer component has been a decreasing proportion of

the total run.





23
between arbitrary groupings of ocean-type fish at dams is not
persuasive. Based on an exhaustive summary of adult salmon
counts at Rock Island Dam from 1933 through 1985, Mullan (1987)
noted that jacks occurred less frequently in the early summer
portion of the run (24%) than in the fall portion (48%).
However, as noted earlier, attempts to partition population
characteristics into run-specific clusters based on dam counts
are tenuous due to inter- and intraseasonal variability in run
timing of Columbia River chinook salmon.

Some of these apparently large differences in jack counts
between early- and late-run ocean-type fish could simply be an
artifact of the census location. For example, during the spring-
run of Columbia River stream-type chinook salmon, jacks tend to
migrate later and are nearly absent during the first third of the
run. This is readily apparent because they are the first run of
the season and, thus, are not overlapped early by another run.
If this pattern holds for runs of ocean-type fish (see the
section on straying below), then many jacks counted as fall-run
chinook salmon may actually be destined for locations generally
associated with early ocean-type, or summer-run fish. The
accuracy of dam counts is also compromised because they include
hatchery fish whose life history traits may have been altered
(e.g., Mullan et al. 1992b).

The percentages of return by age for hatchery upriver
brights have been listed by Howell et al. (1985). For the
1962-79 broods, 2-year-olds (jacks) comprised 34.1% of the total

return, 3-year-olds 23.8%, 4-year-olds 34.6%, and 5-year-olds



59

estimated a probability of less than 0.001% that Priest Rapids
Dam counts of adult summer-run chinook would decline to one fish
by the year 2093.

However, the use of a threshold of one individual is
inconsistent with the methods described by Dennis et al. (1991)
and no confidence intervals were provided for the ADFG result.
Therefore, we concluded that the reliability of this estimate is
questionable. Chapman et al. (1994) applied the model to 5-year
running sums of estimates of summer/fall chinook salmon spawner
abundance based on redd counts above Rock Island Dam. They found
that the probability of decline to 5,000 fish in 10 years was
0.02% (95% confidence interval extends from 0-0.1%) and in 50
years was 9% (confidence interval from 0-50%). Probabilities of
decline to 10,000 fish were estimated to be 3% (95% confidence
interval 0-15%) in 10 years, and 26% (confidence interval 10-93%)
in 50 years.

These results should be viewed with caution: they are based
on a very simple model with unrealistic assumptions regarding
salmon population age structure, they may not include all sources
of variation in stock abundance, they ignore subpopulation
structure, and the estimates had wide confidence intervals.
However, they suggest that the near-term risk of extinction of
this stock is low.

We consider the petitioners’ assessment of hatchery
composition of the stocks to be accurate. Although over 200
million late-run hatchery chinook salmon have been introduced

into the MCR since 1941, their influence on naturally-spawning



61

Table 7. Summary of biological characteristics of stream- and
ecean-type chinook salmon in the mid-Columbia River.

Stream-type Ocean-type
Characteristic Spring-run Summer-run Fall-run
Adult run timing
at Bonneville Dam Mar.-May June-July Aug.-Oct.
General spawning upper tribu- mid tributaries, lower tributaries
locations taries lower tributaries, and mainstem
and mainstem
Spawning time August to mid late September mid October to
September to mid November early December
Seaward juvenile yearling subyearling subyearling
migration
Ocean distribution extended coastal coastal
Morphometric
similarity” a b b
Meristic similarity” a
Genetic similarity’ a b

* Run-types with the same letter are not significantly different.
Morphometric and meristic data from Schreck et al. (1986); genetic
information from Schreck (1986), Utter et al. (1989), Matthews and
Waples (1991), and Marshall (1993, 1994a and b).


62

spring chinook salmon in the MCR as well. Although there is a
lack of genetic information specifically for fall-run fish from
the rivers identified in the petition (Methow, Okanogan, and
Wenatchee), it has been known for some time that there is a close
genetic similarity between mid-Columbia River summer chinook
salmon and fall chinook salmon from the Hanford Reach area.

New data from WDF (Marshall 1993, 1994a and b) included
Hanford Reach natural population and Priest Rapids Hatchery.
Allele frequencies in the Priest Rapids sample did not differ
significantly from those in summer-run adults that returned to
Wells Hatchery, the Wells Dam trap, or the Similkameen River (a

tributary of the Okanogan River).

Phenotypic Characters

Data from one multivariate study of meristic and
morphometric characters of chinook salmon in the Columbia River
Basin indicated that summer and fall chinook salmon from the MCR
are similar to one another but different from other groups of

chinook salmon in the MCR and the Snake River.

Life History Characters

Among MCR and Snake River chinook salmon populations, major
juvenile and adult life history characters match the patterns of
genetic variation. In both rivers, spring chinook salmon are
stream-types and fall chinook salmon are ocean-types. In the
Snake River, summer chinook salmon are stream-types like spring
chinook salmon, while in the MCR, they are ocean-types like fall

chinook salmon. Genetically, Snake River summer chinook salmon



re |

20
is an arbitrary distinction (Fulton 1968, Chapman et al. 1982).
Unfortunately, use of this distinction in accounting methods has
often resulted in large census errors and considerable confusion

regarding the ancestral relationships among chinook salmon

populations in the Columbia River Basin.

Ocean-type chinook salmon in the Columbia River exist in two
basic forms: "upriver brights" and "tules." Upriver brights
enter the river first, mature slowly, and retain their silvery
oceanic coloration well into the freshwater migration. This run

of chinook salmon spawns from somewhere above the site of Grand

Coulee Dam downstream to an area near the present site of The
Dalles Dam. Spawning occurred both in the mainstem Columbia
River and in the lower sections of tributaries (Fulton 1968,
Dauble and Watson 1990) but was probably limited below the mouth
of the Umatilla River (Bryant and Parkhurst 1950). The Snake
River portion of the ocean-type run, historically spawning from
Shoshone Falls downstream to the confluence of the Snake and
Columbia Rivers, was listed as a threatened species under the ESA
(Waples et al. 1991).

Tules are the last chinook salmon to enter the river; they
are sexually mature upon entry and spawn in lower mainstem and
tributary areas primarily below The Dalles Dam (Fulton 1968),
that is, outside the petitioned area.

Currently, ocean-type chinook salmon pass Bonneville Dam
between late May/early June (upriver brights) and late September/
early October (tules) (Howell et al. 1985). The early portion of

the upriver bright run passes Priest Rapids Dam between mid-June


72

Edson, Q. E. 1958. Priest Rapids Fisheries Research Program,
Washington Dep. Fish. Biological Report, 15 p. (Available
Washington Department of Fish and Wildlife, 600 Capitol Way
N., Olympia, WA 98501-1091.)

Fast, D. E., J. D. Hubble, T. B. Scibner, M. Vv. Johnston, W. R.
Sharp. 1989. Yakima/Klickitat natural production and
enhancement program. Report to U.S. Dep. Energy, Contract
DE-A179-88BP93203, project 83-120, 107 p. (Available
Bonneville Power Administration, P.O. Box 3621, Portland, OR
97208.)

Fish, F. F., and M. G. Hanavan. 1948. A report on the Grand
Coulee fish maintenance project 1938-1947. U.S. Fish Wildl.
Serv. Spec. Sci. Rep. Fish. 55:1-63.

Fulton, L. A. 1968. Spawning areas and abundance of chinook
salmon, Oncorhynchus tshawytecha, in the Columbia River
Basin--Past and present. U.S. Fish. Wildl. Serv. Spec. Sci.
Rep. Fish. 571:1-26.

Fulton, L. A., and R. E. Pearson. 1981. Transplantation and
homing experiments on salmon, Oncorhynchus spp., and
steelhead trout, Salmo gairdneri, in the Columbia River
system: Fish of the 1939-44 broods. U.S. Dep. Commer.,
NOAA Tech. Memo. NMFS F/NWC-12, 97 p.

Gilbert, C. H. 1912. Age at maturity of the Pacific coast.
salmon of the genus Oncorhynchus. U.S. Bur. Fish., Bull.
32:1-22 plus plates.

Groves, A. B., G. B. Collins, and P. S. Trefethen. 1968. Roles
of olfaction and vision in choice of spawning site by homing
adult chinook salmon (Oncorhynchus tshawytscha). J. Fish.
Res. Board Can. 25:867-876.

Hard, J. J., R. P. Jones Jr., M. R. Delarm, and R. S. Waples.
1992. Pacific salmon and artificial propagation under the
Endangered Species Act. U.S. Dep. Commer., NOAA Tech. Memo.
NMFS-NWFSC-2, 56 p.

Hasler, A. D., and A. T. Scholz. 1983. Olfactory imprinting
and homing in salmon. Springer-Verlag, New York, 130 p.

Healey, M. C. 1983. Coastwide distribution and ocean
migration patterns of stream- and ocean-type chinook salmon,
Oncorhynchus tshawytscha. Can. Field-Nat. 97(4) :427-433.

Healey, M. C. 1991. Life history of chinook salmon
(Oncorhynchus tshawytscha). In C. Groot and L. Margolis
(editors), Pacific salmon life histories, p. 311-393. Univ.
British Columbia Press, Vancouver.

”



SUMMARY

We have concluded that mid-Columbia River summer chinook
salmon as petitioned are not a species or Evolutionarily
Significant Unit (ESU) as defined by the U.S. Endangered Species
Act (ESA). Rather, they are part of a larger ESU that includes
all late-run (summer and fall), ocean-type chinook salmon from
the mainstem Columbia River and its tributaries (excluding the
Snake River) between Chief Joseph and McNary Dams. We have also
concluded that at the present time this larger ESU is not likely
to become endangered in the foreseeable future and does not

warrant listing as a threatened or endangered species.





9

Evolutionary Significance

Geographic location--The petitioners claim that summer
chinook salmon spawn in two distinct areas: in tributaries of
the Snake River and in tributaries of the MCR above Rock Island
Dam (NEDC et al. 1993, p. 1-2). The petitioners stated that
Methow, Okanogan, and Wenatchee River summer chinook salmon
occupy unique ecosystems with often hostile conditions (NEDC
et al. 1993, p. 9).

Spawning distribution--The petitioners stated that the
original spawning distribution of MCR summer chinook included the
Columbia River as far upstream as Lake Windemere in British
Columbia (NEDC et al. 1993, p. 1), but that currently, MCR summer
chinook salmon spawn only in the Wenatchee, Methow, and Okanogan

Rivers (NEDC et al. 1993, p. 6).

Population Trends

Abundance--The petitioners cited early pioneers’ stories of
millions of salmon, mostly summer chinook, ascending Kettle Falls
(NEDC et al. 1993, p. 5). They state that the abundance of
Columbia River summer chinook salmon has been declining
continuously since 1973, with an adult count over Bonneville Dam
of 15,100 adults in 1992, the lowest count on record. Current
numbers of MCR summer chinook were reported by the petitioners to
be under 9,700 in the Wenatchee, Methow, and Okanogan Rivers
(NEDC et al. 1993, p. 11). The population of summer chinook
salmon in the Entiat River was said to be so small as to be

considered extinct (NEDC et al. 1993, p. 12).



vii

ACKNOWLEDGMENTS

The Biological Status Review of mid-Columbia River summer
chinook salmon was conducted by a team of scientists from the |
Northwest Fisheries Science Center of the National Marine
Fisheries Service. This Biological Review Team relied upon the
extensive public record developed pursuant to the petition. Team
members included Peggy Busby, Dr. David Damkaer, Robert Emmett,
Dr. Stephen Grabowski, Dr. Jeffrey Hard, Dr. Orlay Johnson, Dr.
Conrad Mahnken, Gene Matthews, Dr. Michael Schiewe, Lowell
Stuehrenberg, Dr. Thomas Wainwright, William Waknitz, Dr. Robin
Waples, Laurie Weitkamp, Dr. John Williams, and Dr. Gary Winans.
Bill Hevlin from the Northwest Regional Office of the National
Marine Fisheries Service also contributed information and

participated in discussions.





74

Matthews, G. M., and R. S. Waples. 1991. Status review for
Snake River spring and summer chinook salmon. U.S. Dep.
Commer., NOAA Tech. Memo. NMFS F/NWC-200, 75 p.

McIsaac, D. O., and T. P. Quinn. 1988. Evidence for a heredity
component in homing behavior of chinook salmon (Oncorhynchus
tshawytecha). Can. J. Fish. Aquat. Sci. 45:2201-2205.

McPhail, J. D., and C. C. Lindsey. 1986. Zoogeography of the
freshwater fishes of Cascadia (the Columbia River system and
rivers north to the Stikine). In C. H. Hocutt and E. 0.
Wiley (editors), The zoogeography of North American
freshwater fishes, p. 615-637. John Wiley and Sons,

New York.

Meekin, T. K. 1967. Report on the 1966 Wells Dam chinook
tagging study . Wash. Dep. Fish report to Douglas County
Public Utility District, 41 p. (Available Washington
Department of Fish and Wildlife, 600 Capitol Way N.,
Olympia, WA 98501-1091.)

Meekin, T. K., R. W. Wienhold, and D. Gufler. 1966. Report
on the 1965 Wells Dam chinook tagging study. Wash. Dep.
Fish. report to Douglas County Public Utility Distict,
Contact No. 001-01-022-103, 39 p.. (Available Washington
Department of Fish and Wildlife, 600 Capital Way N, Olympia,
WA 98501-1091.) °

Miller, R. J., and BE. L. Brannon. 1982. The origin and
development of life history patterns in Pacific salmonids.
in E. L. Brannon and E. 0. Salo (editors), Proceedings of
the salmon and trout migratory behavior symposium, Pp. 296-
309. Univ. Washington Press, Seattle.

Milner, A. M., and R. G. Bailey. 1989. Salmonid colonization of
new streams in Glacier Bay National Park, Alaska. Aquacult.
Fish. Manage. 20:179-192.

Mullan, J. W. 1987. Status and propagation of: chinook salmon
in the mid-Columbia River through 1985. U.S. Fish Wildl.
Serv. Biol. Rep. 87(3):1-111.

Mullan, J. W., A. Rockhold, and C. R. Chrisman. 1992a. Life
histories and precocity of chinook salmon in the mid-
Columbia River. Prog. Fish. Cult. 54:25-28.

Mullan, J. W., K. R. Williams, G. Rhodus, T. W. Hillman, and
J. D. McIntyre. 1992b. Production and habitat of salmonids
in mid-Columbia River tributary streams. U.S. Fish. Wildl.
Serv. Monograph 1:1-489.



77

Shaklee, J. B., D. C. Klaybor, S. Young, and B. A. White. 1991.
Genetic stock structure of odd-year pink salmon,
Oncorhynchus gorbuscha (Walbaum), from Washington and
British Columbia and potential mixed-stock fisheries
applications. J. Fish Biol. 39(A) :21-34.

Sneath, P. H. A., and R. R. Sokal. 1963. Numerical taxonomy.
W. H. Freeman, San Francisco, 573 p.

Taylor, E. B. 1988. Adaptive variation in rheotactic and
agnostic behavior in newly emerged fry of chinook salmon,
Oncorhynchus tshawytscha, from ocean- and stream-type
populations. Can. J. Fish. and Aquat. Sci. 45:237-243.

Taylor, E. B. 1989. Adaptive diversification of juvenile life
histories in the chinook salmon, Oncorhynchus tshawytscha
(Walbaum). Ph.D. Thesis, Univ. British Columbia, Vancouver,
283 p.

Taylor, E. B. 1990. Phenotypic correlates. of life history
variations in juvenile chinook salmon, Oncorhynchus
tshawytscha. J. Anim. Ecol. 59:455-468.

Thompson, G. G. 1991. Determining minimum viable populations
under the Endangered Species Act. U.S. Dep. Commer., NOAA
Tech. Memo. NMFS F/NWC-198, 78 p.

Thompson, W. F. 1951. An outline for salmon research in Alaska.
Univ. Washington Res. Inst. Circ. 18, 48 p.

Utter, F. M., P. Aebersold, M. Griswold, G. Milner, N. Putas, J.
Szeles, D. Teel, and G. Winans. 1987. Biochemical genetic
variation of chinook salmon stocks of the mid-Columbia
River. NWAFC Processed Rep. 87-19, 22 p. Northwest Fish.
Sci. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Montlake
Blvd. E., Seattle, WA 98112-2097.

Utter, F., G. Milner, G. Stahl, and D. Teel. 1989. Genetic
population structure of chinook salmon, Oncorhynchus
tshawytscha, in the Pacific Northwest. Fish. Bull., U.S.
87:239-264.

Waples, R. S. 1991. Pacific salmon, Oncorhynchus spp., and
the definition of "species" under the Endangered Species
Act. Mar. Fish. Rev. 53(3):11-22.

Waples, R. S., R. P. Jones, Jr., B. R. Beckman, and G. A. Swan.
1991. Status review for Snake River fall chinook salmon.
U.S. Dep. Commer., NOAA Tech. Memo. NMFS F/NWC-201, 73 p.



15

(Robison 1957). Although some of these irrigation practices have
been corrected, no "summer" chinook salmon (i.e., early part of
late run) have been observed in the Yakima River Basin since the
1970s, most likely due to the presence of inhospitable thermal

conditions for adult chinook in the lower river (Busack 1990).
Life History Characteristics

Detailed life history data (age at spawning, sex ratios,
etc.) are plentiful for many hatchery populations of MCR ocean-
type chinook salmon, but data are limited and inconsistent for
wild populations. Life history characteristics were specifically
identified as "critical data gaps" for most subbasins in the
production plans of the Columbia Basin Fish and Wildlife
Authority (CBFWA 1990). Howell et al. (1985, p.°449) summarized
the situation for Columbia River summer-run fish: “Basic
juvenile and adult life history information is almost completely
unknown for naturally produced summer chinook."

Considering the long history of salmon management by various
fisheries entities, the paucity of basic biological information
is both surprising and discouraging. In the context of an ESA
biological review, this lack of information hampers the
identification of distinct population segments or ESUs. Efforts
to gather detailed life history information have only recently

been initiated.

Juvenile Life History Characters
Chinook salmon populations have been separated into two

basic types based on juvenile life history characteristics: those



NOAA Technical Memorandum NMFS-NWFSC-22

Status Review

for

Mid-Columbia River
Summer Chinook Salmon

July 1995

U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service



78

Washington Department of Fisheries (WDF), Confederated Tribes and
Bands of the Yakima Indian Nation, Confederated Tribes of
the Colville Indian Reservation, and Washington Department
of Wildlife. 1990. Wenatchee River subbasin salmon and
steelhead production plan. (Available Washington Department
of Fish and Wildlife, 600 Capitol Way N., Olympia, WA
98501-1091.)

Washington Department of Fisheries (WDF), Washington Department t
of Wildlife, and Western Washington Treaty Indian Tribes.
1993. 1992 Washington State salmon and steelhead stock
inventory (SASSI), 93 p. plus appendices. (Available
Washington Department of Fish and Wildlife, 600 Capitol
Way N., Olympia, WA 98501-1091.)

Winans, G. A. 1984. Multivariate morphometric variation in
Pacific salmon. I. A technical demonstration. Can. J. Fish.
Aquat. Sci. 41:1150-1159.

Yakima Fisheries Project (YFP). 1992. Draft environmental impact
statement. (Available Bonneville Power Administration,
P.O. Box 3621, Portland, OR 97208-3621.)

Yakima Indian Nation. 1994. Summary statistics for wild and
hatchery production of fall chinook in the Yakima Subbasin,
1983-93. Unpubl. data tables. (Available Yakima Indian
Nation, Fisheries Resource Management, P.O. Box 151,
Toppenish, WA 98948.)

|


38
Table 2. Continued.

Year of Number
Stock® Hatchery” Agency® Class Plant Stream* Planted

Release site not specified - Summer chinook salmon

GCFMP LEAV FWS -- 43 -- 218,000
Leav LEAV FWS fingerling 49 -- 50,600 ‘
Leav LEAV FWS fingerling 51 -- 10,300 .
Leav LEAV FWS fingerling 52 -- 139,300

Total = 418,200

Stock Abbreviations

GCFMP. = Grand Coulee Fish Maintenence Project : |
Methow = Methow River

Carson = Carson National Fish Hatchery

Entiat = Entiat National Fish Hatchery

Sprng Cr. = Spring Creek National Fish Hatchery

Wells = Wells Hatchery and/or Wells Spawning Channel

Leav = Leavenworth National Fish Hatchery

Wenatch = Wenatchee River

L White = Little White Salmon National Fish Hatchery

Eagle cr. = Eagle Creek National Fish Hatchery

Priest = Priest Rapids Hatchery

Simpson = Simpson Hatchery

Col. R. = mainstem mid-Columbia River

Elokomin = Elokomin Hatchery

Bonn = Bonneville Hatchery (Oregon Dep.of Fish and Wildlife)
Sn X Pr = Snake River by Priest Rapids hybrids

Wells (F) = Wells Hatchery/Spawning Channel fall chinook salmon
unknown = origin unknown or unspecified

> Hatchery Abbreviations

LEAV = Leavenworth National Fish Hatchery

ENT = Entiat National Fish Hatchery

WINT = Winthrop National Fish Hatchery

WELLS = Wells Hatchery and/or spawning channel

ROCK I = Rock Island Hatchery

ROCK R = Rocky Reach Hatchery and/or spawning channel

RING = Ringold Rearing Ponds (
SPRING = Spring Creek National Fish Hatchery

BUR Bureau of Reclamation

YAK = various acclimation facilities

© Agency Abbreviations
FWS = United States Fish and Wildlife Service i

WDF = Washington Deapartment of Fish and Wildlife
COOP = Cooperative effort between WDF and another party
ODFW = Oregon Department of Fish and Wildlife
4 Class: fry = post hatchling
unknown = size/age unknown or not specified
* =

includes both spring and summer chinook salmon

* Stream (location planted): (V) = at Vantage
. (RG)= at Ringold



2
Biological Review Team (BRT). Because Previous studies have
consistently found genetic and life-history similarities between
summer- and fall-run chinook salmon in the middle Columbia River
above McNary Dam, the BRT also considered information for this
larger group. In this review, both summer- and fall-run chinook
salmon will be referred to as "late-run" chinook salmon or
stocks. Fall-run chinook salmon in the Snake River were listed

as threatened in 1992 (NMFS 1992).

KEY QUESTIONS IN ESA EVALUATIONS

Two key questions must be addressed in determining whether a

listing under the ESA is warranted:

1) Is the entity in question a "species" as defined by the

ESA?

2) If so, is the "species" threatened or endangered?
The "Species" Question

As amended in 1978, the ESA allows listing of "distinct
population segments" of vertebrates as well as named species and
subspecies. However, the ESA provided no specific guidance for t
determining what constitutes a distinct population, and the
resulting ambiguity led to the use of a variety of criteria in
listing decisions over the past decade. To clarify the issue for
Pacific salmon, NMFS published a policy describing how the agency
will apply the definition of "species" in the ESA to anadromous
salmonid species, including sea-run cutthroat trout and steelhead

(NMFS 1991). A more detailed description of this topic appeared


INTRODUCTION

Chinook salmon (Oncorhynchus tshawytscha) are distributed
from central California to northern Alaska on the North American
coast and are native to the Columbia River Basin (Healey 1991).
This species was once extremely abundant throughout most of the
basin’s large, complex river system (Chapman 1986) and has often
been partitioned into three races (spring, summer, and fall)
based upon timing of adult entry into fresh water. From the late
19th century until the present, a variety of factors have led to
a reduction in many Columbia River chinook salmon populations
(Nehlsen et al. 1991).

This situation prompted American Rivers, Northwest
Environmental Defense Center, The Sierra Club, Northwest Resource
Information Center, Friends of the Earth, Inland Empire Public
Lands Council, Washington Wilderness Coalition, North Central
Washington Audubon Society, Trout Unlimited, Washington Trout,
and Federation of Fly Fishers (NEDC et al. 1993) to petition the
National Marine Fisheries Service (NMFS) to list mid-Columbia
River? summer-run chinook salmon as a threatened or endangered
species under the U.S. Endangered Species Act (ESA) of 1973
(U.S.C. 1531 et seq.).

This report summarizes a review of the biological status of
mid-Columbia River summer-run chinook salmon. This review was

conducted by the NMFS Northwest Fisheries Science Center

+ Mid-Columbia was used by the petitioners to refer to the
Columbia River Basin between Priest Rapids and Chief Joseph
Dams.



$1

Table 4. Recent qualitative assessments of status of ocean-type
chinook salmon stocks in the mid-Columbia region
(Nehlsen et al. 1991, WDF et al. 1993).

Nehlsen et al. >
River Basin Run Risk Level* Origin Production Status
Similkameen Summer -- -—- -- --
Okanogan Summer Special Concern Native © Wild Depressed
Methow Summer Moderate Mixed wild Depressed

risk

Lake Chelan Fall -- Nonnative Wild Healthy
Entiat Summer Extinct -- -- --
Wenatchee Summer -- Mixed wild Healthy
Hanford Fall ated Native wild Healthy
Yakima Fall -- Unknown Composite Healthy
Marion Drain Fall -- Native wild Healthy

* Nehlsen et al. (1991) identified stocks as extinct, at high risk of
extinction, at moderate risk of extinction, or of special concern. Their
list did not include stocks that did not qualify for one of these
categories. The dash indicates that the stock(s) was not mentioned.

» SASSI ("Salmon and Steelhead Stock Inventory," WDF et al. 1993) classified
stocks by apparent genetic origin (native, nonnative, or mixed), by current
production type (wild, hatchery, or composite), and by apparent stock status
(critical, depressed, or healthy). These are preliminary classes, subject
to later refinement, and reflect the consensus opinion of state and tribal
biologists contributing to the report. Dash indicates that the stock(s) was
not mentioned.



34

Table 2. Continued.

Year of Number

Stock*® Hatchery” Agency* Class* Plant Stream* Planted
Entiat WINT FWS fingerling 47 Methow R. 112,131
Entiat WINT FWS fry 47 Methow R. 94,681
Methow WINT FWws fry* Si Methow R. 150,341
Methow WINT Fws fingerling* 52 Methow R. 31,390
Methow WINT FWS fry* 52 Methow R. 151,140
Methow WINT FWSs fingerling* 56 Methow R. 69,487
Methow WINT FWS fry* s7 Methow R. 66,937
Wells WINT FWs yearling 77 Methow R. 213,355
Wells WINT FWS yearling 78 Methow R. 501,664
Wells WINT FWS yearling 719 Methow R. 236,787
Wells WINT FWS yearling 81 Methow R. 170,500
Wells WINT PWS yearling 82 Methow R. 268,100
Methow WINT Fws yearling 83 Methow R. 170,500
Wells WELLS WDF fingerling 87 Methow R. 212,732
Wells WELLS WDF fingerling 98 Methow R. 212,413
Wells ROCK I WDF yearling 91 Methow R. 420,000
Wells ROCK I WDF yearling 92 Methow R. 391,650
Wells ROCK I WDF yearling 93 Methow R. 540,900
Total = 4,754,508
Wenatchee River plants - Summer chinook salmon .
GCFMP LEAV FWS fingerling* 41 Icicle R. 135,500
GCFMP LEAV FWS fingerling* 42 Icicle R 200,800
GCFMP LEAV FWS fingerlingt 44 Icicle R. 59,000
Leav LEAV Fws unknown 46 Icicle R. 9,000
Leav LEAV FWws yearling 47 Icicle R 73,000
Leav LEAV Fws fingerling 53 Icicle R. 80,700
Leav LEAV FWS fingerling 55 Icicle R. 21,200
Leav LEAV Fws fingerling 56 Icicle R. 1,200
Leav LEAV Fws fingerling 57 Icicle R. 6,700
Leav LEAV FWs fingerling 58 Icicle R. 79,800
Leav LEAV FWS fingerling 59 Icicle R. 3,700
Leav LEAV FWS fingerling 60 Icicle R. 19,000
Leav LEAV FWS fingerling 61 Icicle R. 10,200 |,
Leav LEAV FWS fingerling 62 Icicle R. 6,500 &
Wenatch ROCK I. - WDF yearling 91 Wenatchee R.720,000
Wenatch ROCK I WDF yearling 92 Wenatchee R.124,400
Wenatch ROCK I WDF yearling 93 Wenatch R.__191,179
Total = 1,741,879
Wenatchee River plants - Fall chinook salmon é
GCFMP LEAV FWS fingerling 43 Icicle cr. 70,900
LWhite LEAV FWS fingerling 46 Icicle Cr. 616,000
Sprng Cr. LEAV FWS fry 65 Icicle Cr.2,854,000
Sprng Cr. LEAV Fws fingerling 65 Icicle cr. 68,000
Eagle Cr. LEAV FWS fry 67 Icicle Cr.__659,000

Total = 4,267,900



78

National Marine Fisheries Service (NMFS). 1991. Notice of
policy: Policy on applying the definition of species under
the Endangered Species Act to Pacific salmon. Federal
Register [Docket No. 910248-1255, 20 November 1991]

56 (224) :58612-58618. .

National Marine Fisheries Service (NMFS). 1992. Final rule:
Threatened status for Snake River spring/summer chinook
salmon, threatened status for Snake River fall chinook
salmon. Federal Register [50 CFR Part 227;Docket No.
910847-2043, 22 April 1992] 57(78) :14653-14663.

Nehlsen, W., J. E. Williams, and J. A. Lichatowitch. 1991."
Pacific salmon at the crossroads: Stocks at risk from
California, Oregon, Idaho, and Washington. Fisheries
16(2) 24-21.

Nei, M. 1978. Estimation of average heterozygosity and genetic
distance from a small number of individuals. Genetics
89:583-590.

Northwest Environmental Defense Center (NEDC), American Rivers,
Sierra Club, Northwest Resource Information Center, Friends
of the Earth, Inland Empire Public Lands Council, Washington
Wilderness Coalition, North Central Washington Chapter
Audubon Society, Trout Unlimited, Washington Trout,
‘Federation of Flyfishers. 1993. Petition for a rule to
list mid-Columbia River summer chinook salmon as threatened
or. endangered under the Endangered Species Act and to
designate critical habitat. Unpubl. manuscr., 28 p.
Document submitted to the U.S. Dep. Commer., Washington,
D.C., June 1993. (Available Northwest Environmental Defense
Center, 10015 S.W. Terwilliger Blvd., Portland, OR 97219.)

Oregon Department of Fish and Wildlife (ODFW) and Washington
Department of Fisheries (WDF). 1993. Status report
Columbia River fish runs and fisheries 1938-92, 257 p.
(Available Oregon Department of Fish and Wildlife, P.O. Box
59, Portland, OR 97501.)

Park, D. L. 1969. Seasonal changes in downstream migration
of age-group 0 chinook salmon in the upper Columbia River.
Trans. Am. Fish. Soc. 98:315-317.

Platts, W. S. 1991. livestock grazing. In W. R. Meehan
(editor), Influences of forest and rangeland management,
p. 389-423, Am. Fish. Soc. Spec. Publ. No. 19, Bethesda,
MD.

Quinn, T. P. 1993. A review of homing and straying of wild
and hatchery-produced salmon. Fish. Res. 18:29-44.


|

22
and allocate Columbia River chinook salmon are not necessarily
recognized by the fish themselves. As Mullan (1987, p. 57)
stated, "There are no clear differences between summer-run and
fall-run chinook salmon in the mid-Columbia."
Fish from later in the run spawn primarily in the Hanford

Reach below Priest Rapids Dam from late October to late December.

A small number of fish not passing Priest Rapids Dam spawn in
lower areas of the Yakima River in October and November (CBFWA
1990, WDF et al. 1993). Below McNary Dam, another small run of
upriver brights enters the Deschutes River over a protracted
period from late June to October, spawning in mainstem areas
below Pelton Reregulating Dam from October through December
(CBFWA 1990). According to Howell et al. (1985) the John Day
River supports a "negligible" run of upriver brights; however, no

data have been obtained for these fish.

Age at Spawning, Sex Ratio, and Fecundity

Area-specific data for age at spawning, adult sex ratios,
and fecundity are generally lacking for wild populations of MCR
chinook salmon. A life history characteristic that appears to
differ among the three alleged forms of Columbia River chinook t
salmon is the abundance of early-maturing males, known as jacks
(Howell et al. 1985). Generally, jacks are least abundant in
stream-type chinook salmon populations and become progressively

, more abundant over the duration of the ocean-type run (Mullan

1987, Healey 1991, Mullan et al. 1992a).

However, because so-called summer- and fall-run fish were

not observed in natural spawning areas, the difference noted



39
of Grand Coulee Dam (discussed below). Three factors appear to
be primarily responsible for the increase: 1) the number of
ocean-type chinook salmon in the MCR in the early 1940s was
extremely low, so any improvements to the system would result in
an increase; 2) at least partial success of the Grand Coulee Fish
Maintenance Project, which corrected some practices harmful to
salmon and began supplementation efforts in the MCR Basin (Fish
ana Hanavan 1948), and 3) displacement of upriver stocks into the

Hanford Reach.

Grand Coulee Fish Maintenance Project, 1939-43

The single most important event affecting the distribution
of ocean-type chinook salmon in the middle and upper Columbia
River was the construction of the Grand Coulee Dam (RKm 959) in
1939, which completely eliminated passage of anadromous salmon
above that point. To compensate for the loss of habitat, the
federal government initiated the Grand Coulee Fish Maintenance
Project (GCFMP). The GCFMP sought to maintain fish runs in the
Columbia River above Rock Island Dam (RKm 730) by two means:

1) improving salmonid habitat; and 2) establishing hatchery
operations (Fish and Hanavan 1948).

The primary method of habitat improvement during the GCFMP
was the obligatory installation of screens on irrigation
diversions in tributaries of the mid-Columbia River. The screens
prevented juvenile chinook salmon from being drawn into
irrigation systems and presumably made a major contribution to
the increase in MCR populations since the 1940s (discussed

below). In contrast, chinook salmon populations in the Yakima



21
and early August and spawns primarily in the lower reaches of the
petitioned tributary streams above Rock Island Dam from late.
September through early November. In the area above Rock Island
Dam, summer- and fall-run adults intermingle and spawn at the
same time (Edson 1958, Mullan 1987, Craig and Suomela 1941). For
example, Meekin (1967) and Meekin et al. (1966) could not
distinguish mainstem spawners (presumably fall-run) from
tributary spawners (presumably summer-run) based on time of
passage over Wells Dam.

Naturally produced, summer-run chinook salmon introduced
into the Wells summer chinook spawning channel have been observed
spawning as late as mid-December (Allen et al. 1971), at least a
month later than so-called summer chinook salmon are said to
spawn (NEDC et al. 1993). Conversely, chinook salmon designated
as fall-run according to their run timing have been observed
spawning in the Priest Rapids fall chinook spawning channel as
early as mid-September (Allen 1966, 1967). This spawn timing is
more typical of summer- or even spring-run chinook salmon,
according to some criteria (NEDC et al. 1993).

Recently, radio-tag data evaluating segregation of chinook
salmon populations by run timing at’ dams showed that a
significant portion of summer-run adults spawned in the mainstem
Columbia River, while a significant portion of fall-run adults
spawned in the Okanogan River system (L. Stuehrenberg, unpubl.
data, NMFS). The petitioners claimed that the Okanogan River
contains summer-run fish only (NEDC et al. 1993). However, it is

apparent that the run times used by fishery managers to partition



150,000 +

s
@
2 100,000 +
]
3
a
50,000
0 + + + + + 1
1960 1965 1970 1975 1980 1985 1990 1995

Year

Figure 6. Estimated total adult run size for the ESU, 1964-93. Run size was estimated from
total summer- and fall-run chinook salmon counts at McNary Dam with Snake
River fish (Ice Harbor Dam counts) and returns to Priest Rapids and Wells
Hatcheries subtracted. Data from the Coordinated Information System
Computerized Distributed System (Anderson 1994), ODFW and WDF (1993), and
Chapman et al. (1994),




12
the Cascade Mountains as relatively short streams that begin
precipitously and make a transition to low gradient streams in
the lower reaches.. These rivers receive the majority of their
runoff from snowmelt in the spring and early summer. The five
major east-slope rivers of the Cascade Mountains are the Yakima,
Wenatchee, Entiat, Methow, and Okanogan (Fig. 1). General
habitat features of these rivers are presented in Table 1 (see
also Chapman et al. 1994).

The eastern side of the MCR is a basaltic plateau that
reaches 763 m in elevation and is principally xeric, sagebrush-
grassland habitat. Between the Grand Coulee Dam and the Snake
River, there are no chinook salmon streams entering the MCR from
the eastern side.

In general, the five major MCR tributaries are not
biologically productive. At certain size-at-age classes,
resident trout populations in the Methow, Entiat, and Wenatchee
Rivers have standing crop levels among the lowest ever reported
(summarized in Mullan et al. 1992b). The habitat quality index

. Score for these three rivers was 47 on a scale of 11 to 113,
indicating low overall potential for salmonid spawning and
rearing (Mullan et al. 1992b). Among MCR tributaries, the
Okanogan River, which flows through four mainstem lakes, is
somewhat more fertile. The Yakima River is presently enriched
due to agricultural runoff and reservoir storage. Overall water
quality in the other petitioned streams is excellent (Mullan

et al. 1992b).

~



76

Quinn, T. P., and K. Fresh. 1984. Homing and straying in
chinook salmon, Oncorhynchus tshawytscha, from Cowlitz River
Hatchery, Washington. Can. J. Fish. Aquat. Sci.
41:1078-1082.

Reimers, P. E. 1968. Social behaviour among juvenile fall
chinook salmon. J. Fish. Res. Board Can. 25:2005-2008.

Rich, W. H. 1920. Early history and seaward migration of
chinook salmon in the Columbia and Sacramento Rivers. U.S.
Bur. Fish., Bull. 37:1-74.

Rich, W. H., and H. B. Holmes. 1928. Experiments in marking
young chinook salmon on the Columbia River 1916 to 1927.
U.S. Bur. Fish., Bull. 44:215-264.

Richards, J., and D. Olsen. 1993. Inter-basin comparison study:
Columbia River salmon production compared to other west
coast production areas, 20 p. plus appendices. (Available
U.S. Army Corps of Engineers, 319 S.W. Pine, Portland, OR
97201.)

Ricker, W. E., 1981. Changes in the average size and average
age of Pacific salmon. Can. J. Fish. Aquat. Sci.
38:1636-1656.

Robison, R. S. 1957. The Yakima River. Historical and present
Indian fishery. Wash. Dep. Fish. unpubl. manuscr., April
1957, 18 p. (Available Washington Department of Fish and
Wildlife, 600 Capitol Way N., Olympia, WA 98501-1091.)

Schreck, C. B., H. W. Li, R. C. Hjort, Cc. Ss. Sharpe, K. P.
Currens, P. L. Hulett, S. L. Stone, and S. B. Yamada. 1986.
Stock identification of Columbia River chinook salmon and
steelhead trout. Report to U.S. Department of Energy,
Contract DE-A179-83BP13499, project 83-451, 184 p.
(Available Bonneville Power Administration, P.O. Box 3621,
Portland, OR 97208.)

Scott, J. W. (with C. R. Vasquez, J. G. Newman, and B. Cc.
Sarjeant). 1989. Washington, a centennial atlas. Western
Wash. Univ. Press, Bellingham, 155 p.

Sedell, J. R., and F. J. Swanson. 1984. Ecological
characteristics of streams in old-growth forests of the
Pacific Northwest. In W. R. Meehan, T. R. Merrill, Jr., and
T. A. Hanley (editors), Proceedings of the symposium on fish
and wildlife relationships in old-growth forests, p. 9-16.
Am. Inst. Fish. Res. Biol., Asheville, NC.

Seufert, 1980. Wheels of fortune. Oregon Historical Society,
Portland, OR, 259 p.



49
Estimates of fall chinook salmon from 1983 to 1987 averaged 570
(range 221 to 1,332; Fast et al. 1989).
There is some historical evidence that chinook salmon
upstream from the MCR underwent periodic fluctuations in
abundance. Native Americans in this portion of the Columbia

River Basin traditionally depended on salmon for subsistence.

Yet episodes of starvation among Native American tribes were
recorded in 1811, from 1826 to 1829, and in 1831 (Mullan et al.
1992b). These episodes appear to be linked to the failure of
chinook salmon to return to Kettle Falls, the primary aboriginal
fishing area on the upper-Columbia River (Fig. 1), in sufficient
numbers to sustain the local population (Mullan et al. 1992b).

In 1831, salmon had to be procured from Fraser River tribes to
sustain the traders at Fort Walla Walla through the winter, since
few Columbia River chinook salmon had been caught the previous
summer. Assuming that spawning and rearing habitat were still
pristine at the time, it is likely that variations in ocean
conditions were responsible for the extreme fluctuations of
chinook salmon populations of the upper Columbia River observed
by the earliest settlers (Mullan et al. 1992b). Similarly,
chinook salmon abundance in the Fraser River--an undammed river
system--has fluctuated substantially over time, apparently due to

variations in ocean conditions (Richards and Olsen 1993).

Present Abundance Estimates and Trends
In considering whether ocean-type chinook salmon of the MCR
are threatened or endangered according to the ESA, we evaluated

both qualitative and quantitative information. Qualitative



|

73

Hershberger, W. K., D. Dole, and X. Duo. 1988. Genetic
identification of salmon and steelhead stocks in the mid-
Columbia River. Report to Don Chapman Consultants, Inc.,
29 p. plus appendices. (Available Don Chapman Consultants,
3653 Rickenbacker, Ste. 200, Boise, ID 83705.)

Hill, P. M.. 1984. A detailed listing of the liberations of
salmon into the open waters of the state of Washington
during 1983. Wash. Dep. Fish. Prog. Rep. 210:1-369.

Howell, P., K. Jones, D. Scarnecchia, L. LaVoy, W. Kendra, D.
Ortmann, C. Neff, C. Petrosky, and R. Thurow. 1985. Stock
assessment of Columbia River anadromous salmonids. Volume
I: Chinook, coho, chum, and sockeye stock summaries. Report
to U.S. Dep. Energy, Contract DE-A179-84BP12737, project
83-335, 585 p. (Available Bonneville Power Administration,
P.O. Box 3621, Portland, OR 97208.)

Kirby, L. L. 1985. A detailed listing of the liberations of |
salmon into the open waters of the state of Washington
during 1984. Wash. Dep. Fish. Prog. Rep. 231:1-180.

Lister, D. B, and C. E. Walker. 1966. The effect of flow
control on freshwater survivial of chum, coho, and chinook
salmon in the Big Qualicum River. Can. Fish Cult. 37:3-25.

Marshall, A. 1993. Memo to ESA Administrative Record for mid-
Columbia River summer chinook salmon re: Analysis of
genetic data, July 26, 1993, 4 p. and enclosures.
(Available Environmental and Technical Services Division,

Natl. Mar. Fish. Serv., 525 N.E. Oregon Street, Portland, OR
97232-2737.)

Marshall, A. 1994a. Memo to ESA Administrative Record for
mid-Columbia River summer chinook salmon re: Cluster
analysis of genetic data and baseline information, March 22,
1993, 2 p. and enclosures. (Available Environmental and
Technical Services Division, Natl. Mar. Fish. Serv.,

525 N.E. Oregon Street, Portland, OR 97232-2737.)

Marshall, A. 1994b. Memo to ESA Administrative Record for
mid-Columbia River summer chinook salmon re: Cluster
analysis of genetic data and enzyme loci, April 12, 1994,
1p. and enclosure. (Available Environmental and Technical
Services Division, Natl. Mar. Fish. Serv., 525 N.E. Oregon
Street, Portland, OR 97232-2737.)

Mathews, S. B., and T. K. Meekin. 1971. Fecundity of fall
chinook salmon from the upper Columbia River. Wash. Dep.
Fish. Tech. Rep. 6:29-37.



79
Appendix. Protein loci and sample information for genetic
analyses presented in Figures 2 and 3 (Marshall 1994a and b).

Loci used in genetic analysis:

MAAT-1*, SAAT-1,2*, SAAT-3*, SAAT-4*, ADA-1*, ADA-2*, sAH*,
MAH-4*, GPI-B2*, GPI-At, GR*, HAGH* =2* *

: , SIDHD-1*,
sSIDHp-2*, LDH-B2*, LDH-C*, sMDH-Al,2*, sMDH-B1.2*, mMDH-2*, MPI*,
PEPA*, PEP-Bl*, PEPD-2*, PEP-LT*, PGDH*, PGK-2*, PGM-1*, PGM-2*,
sSOD-1*, mSOD-1*, msOD*, and TPI-a*

Sample information for genetic samples:

Run Years
Sample type sampled Comments
Hanford Reach fall 1990 mainstem Columbia River
Bonneville Hatchery fall 1990
Little White Salmon Hatchery fall 1990
Priest Rapids Hatchery fall 1987, 90, 91
Lyons Ferry Hatchery fall 1990, 91 Snake River, all tagged
adults :
Wenatchee River summer 1989-92
Wells Hatchery summer 1991-92
Similkameen River summer 1991-92
Winthrop Hatchery spring 1992
Leavenworth Hatchery spring 1991
White River spring 1989, 91-92 Wenatchee River tributary
Nason Creek spring 1989, 92 Wenatchee River tributary
Chiwawa River spring 1989-92 Wenatchee River tributary
Carson Hatchery spring 1989
American River spring 1989-92
Naches River spring 1989-92 includes Little Naches
and Bumping River
Upper Yakima spring 1989-92 includes Cle Elum River
Yakima River fall 1990-92
Marion Drain fall 1989-92

Sandy River fall 1990-92 lower Columbia River



56

Counts of late-run ocean-type adult chinook salmon in 1991
and 1992 at mid-Columbia River dams were well below the 10-year
average, and at some dams the 1992 counts were record lows. In
1993, counts at all dams were well above the 1992 low point, and
most were near or above the recent (1984-93) 10-year average.
While the low counts in 1991 and 1992 are of concern, they are
not unprecedented. Similar low counts occurred in 1982 and 1983,
after which counts increased to reach record highs at Priest
Rapids and Rock Island Dams in the late 1980s. Average run-size
and trend estimates for these dams are summarized in Table 6.

Total abundance of MCR ocean-type chinook salmon is
relatively large, with a recent (1989-93) 5-year average annual
estimate of 22,000 adults Passing Priest Rapids Dam. An
additional 42,000 adults spawned in the Hanford Reach and Yakima
River, for a total 5-year average annual run of approximately
64,000 MCR ocean-type chinook salmon (Fig. 6). The number of
fish spawning in Hanford Reach and Yakima River was estimated
from McNary Dam counts, with counts from Priest Rapids Dam, Ice
Harbor Dam, and various hatcheries subtracted. Note, however,
that these estimates may be subject to large errors.

NMFS has not attempted to estimate extinction probabilities
for these stocks and in previous status reviews has viewed such
estimates with caution. However, two reports submitted to the
administrative record (ADFG 1993, Chapman et al. 1994) have
attempted such estimates. Both applied the model of Dennis
et al. (1991) to an aggregate stock of mid-Columbia River chinook

salmon. The Alaska Department of Fish and Game (ADFG 1993)

ee



29
salmon, particularly the largest individuals (Thompson 1951,
Beiningen 1976). Some commercial fishing methods have been shown
to dramatically reduce the mean size and age of chinook salmon

populations (Ricker 1981).

Straying

Adult anadromous salmonids that spawn in areas other than
their natal stream or hatchery are known as strays. However,
some strays may actually be wanderers, as described by Chapman
et al. (1991). Wandering fish enter nonnatal streams or areas
and eventually depart to spawn elsewhere. Tagging data indicate
that wandering may be a relatively common behavior in anadromous
salmonids (Meekin 1967, Bjornn et al. 1992), especially in areas
where hatchery releases occur close to spawning areas (Chapman
et al. 1994). Unnatural obstacles (dams, weirs, traps, etc.) may
partially or totally prohibit corrections or adjustments by these
fish. In situations such as these, where voluntary egress is
prevented, wandering fish may be falsely classified as strays.

Homing is well developed in anadromous salmonids, with
olfactory cues providing the primary mechanism for river,
tributary, and possibly even riffle selection (Groves et al.
1968, Hasler and Scholz 1983). Homing to specific natal
environments has undoubtedly influenced the genetic interaction
among neighboring populations, and in general, there is a
decreasing likelihood of gene flow between salmon populations as
geographic distance between them increases (see Quinn 1993, Utter

et al. 1989, Shaklee et al. 1991). For example, it can be safely



69
CITATIONS

Abrahamson, P. 1986. A detailed listing of the liberations
of salmon into the open waters of the state of Washington
during 1985. Wash. Dep. Fish. Prog. Rep. 243:1-432.

Abrahamson, P. 1987. A detailed listing of the liberations
of salmon into the open waters of the state of Washington
during 1986. Wash. Dep. Fish. Prog. Rep. 259:1-424.

Abrahamson, P. 1988. A detailed listing of the liberations
of salmon into the open waters of the state of Washington
during 1987. Wash. Dep. Fish. Prog. Rep. 267:1-447.

Alaska Department of Fish and Game (ADFG). 1993. Comments
concerning status of mid-Columbia River summer chinook
salmon, submitted to ESA Administrative Record, October
1993, 21 p. (Available Environmental and Technical Services
Division, Natl. Mar. Fish. Serv., 525 N.E. Oregon Street,
Portland, OR 97232.)

Allen, R. L. 1966. Annual Report of Priest Rapids fall chinook
salmon spawning channel. Wash. Dep. Fish. 1966:1-51

Allen, R. L. 1967. Annual Report of Priest Rapids fall chinook
salmon spawning channel. Wash. Dep. Fish. 1967:1-33.

Allen, R. L., B. D. Turner, and J. E. Moore. 1971. Annual
Report of Wells summer chinook salmon spawning channel.
Wash. Dep. Fish. 1971:1-18.

Anderson, D. A. 1994. Coordinated information system: May,
1994 distributed system documentation. Report to U.S. Dep.
Energy, Contract DE-FC79-89BP94402, project 88-108, 53 p.
(Available Bonneville Power Administration, P.O. Box 3621,
Portland, OR 97208.)

Beiningen, K. T. 1976. Fish runs. In Investigative reports of
Columbia River fisheries project, p. El-E65. Pacific
Northwest Regional Commission, Vancouver, WA.

Bjornn, T. C., R. R. Ringe, K. R. Tolotti, P. J. Keniry, and
J. P. Hunt. 1992. Migration of adult chinook salmon and
steelhead past dams and through reservoirs in the lower
Snake River and into tributaries-1991. Idaho Cooperative
Fisheries Research Unit, U.S. Fish Wildl. Serv. Tech. Rep.
72-2:1-55.



30
assumed that Alaskan stream-type chinook salmon do not stray into
the Columbia River system.

While mixing between the same types of geographically-
proximal chinook salmon stocks is undoubtedly greater, the extent
to which it occurs naturally is not well understood. It is
becoming increasingly apparent, however, that vacant habitat can
be recolonized relatively quickly by salmonids from nearby
populations (Milner and Bailey 1989).

Accounts of straying by Columbia River chinook salmon
populations are confusing and have focused primarily on hatchery
fish. Chapman et al. (1991, 1994) concluded that stream-type
chinook salmon stray less than ocean-types. However, Rich and
Holmes (1928) concluded the opposite.

Tule chinook salmon from the Washington Department of
Fisheries Cowlitz Hatchery exhibited an average home-stream
fidelity of 98.6% for four brood years (Quinn and Fresh 1984).
Older fish tended to stray the most and jacks, returning later in
the year, strayed the least. Straying also appeared to be
related to brood-year success, with higher straying rates
occurring when survival was low.

McIssac and Quinn (1988) reported 99% homing accuracy for
upriver brights released from Priest Rapids Hatchery. These
authors reported that homing appeared to be somewhat under
genetic control. If this is true, then the large assortment of
recent stock relocations, primarily for various hatchery or
enhancement purposes, may have increased straying and therefore

the mixing of Columbia River salmon. In fact, the petitioned



4s

0.032 0.0267 0.0213 0.0160 0.0107 0.0053 0.0000

eee cpcclagerechessebeceebeccabeceedeetshercebeecsbessetessst
HANFORD REACH FA
PRIEST RAP. H. FA
WENATCHEE SU
WELLS H. SU
SIMTLKAMEEN SU
BONNEVILLE H. FA
1 YAKIMA FA

LW. SALHON H. FA
DESCHUTES FA

-— LYONS FERRY H. FA
L_ MARION DRAIN FA
SANDY FA
WINTHROP H. SP
LEAVENWORTH H. SP
HASON SP

GARSON H. SP
CHIWAWA SP

JOHN DAY SP
YAKIMA. SP

WHITE SP
AMERICAN SP
WACHES/L.NAC/BHP. SP
ROUND BUTTE H. SP

rar

be ennbe eee.
0.032 0.0267

NEI (1978) UNBIASED GENETIC DISTANCE

+
-0000

0.0213

Figure 2. Genetic relationships among selected samples of

chinook salmon in the Columbia River Basin based on
Nei’s unbiased genetic distance (1978) and unweighted,

pair-group method and arithmetic averages (UPGMA;

Sneath and Sokal, 1963) for 36 loci (Marshall 1994a

and b). Loci used and sample information are
described in the Appendix. SP = spring-run, SU =
summer-run, and FA = fall-run.



18
Run and Spawn Timing

The temporal distribution of adults as they enter fresh
water to spawn is referred to as run timing. Historically,
chinook salmon have entered the mouth of the Columbia River
almost continuously. Commencing in February, the run peaked in
mid-June and ended in late November (Thompson 1951, Mullan 1987).
In general, early-returning fish were stream-types destined for
upper tributary areas, while late-returning fish were ocean-types
destined for mainstem areas (Fulton 1968).

However, during the peak of chinook salmon migration, a
large number of both run-types migrated upstream, filling a large
portion of the spawning habitat. Thus, the so-called "summer-
run" was a mix of chinook salmon composed of late-migrating
stream-type fish destined for upper tributaries of the Snake and
Columbia Rivers and early-migrating ocean-type fish destined for
lower tributary and mainstem areas of the middle Columbia and
Snake Rivers.

Since the turn of the century, human activities (i.e.,
overfishing, dam building, etc.) have severely fragmented or
dislocated portions of the ancestral continuum of migrating
chinook salmon in the Columbia River, leaving what now appears as
noncontinuous or discrete populations. The middle portion was
depleted by early commercial harvests, leaving the early (spring-
run) and late (fall-run) portions separated as semidiscrete run
groups (Thompson 1951, Beiningen 1976).

Because chinook salmon spawning coincides with a declining

temperature cycle (Miller and Brannon 1982), temperature



48
Similkameen River (summer-run) samples, and it differed only
slightly from the Wenatchee River (summer-run) sample
(0.01 < P < 0.05).

These same patterns of genetic variation among populations
of chinook salmon in the basin have also been reported by other
investigators. Using similar clustering analyses of allozyme
data sets based on fewer loci, Schreck et al. (1986), Utter
et al. (1987), and Hershberger et al. (1988) all found a close
relationship between summer- and fall-runs in the MCR. Utter
et al. (1989) also showed a high similarity between "fall-run"
and "summer-run" samples in the MCR using multidimensional

analysis of allozyme data.
POPULATION ABUNDANCE AND THRESHOLD EVALUATIONS

Historic Abundance Estimates and Trends

Historic abundance estimates for chinook salmon in the upper
and middle Columbia River Basin are in the hundreds of thousands
(Mullan 1987). However, with the advent of commercial fisheries
in the 1800s, these populations were declining by 1900. A well-
documented example of this pattern of change concerns stocks in
the Yakima River. Estimates of salmon returns (all species) to
the Yakima River in the mid-1800s range from 160,000 to 250,000
(Robison 1957). With agricultural and fisheries development, the
run size (all species) fell to 20,000 from 1875 to 1905, and then
dropped to-1,000 around 1930 (Robison 1957). Summer run chinook

salmon were last seen in the Yakima River in 1970 (YFP 1992).



57
Table 6. Summary of recent 5-year average (1989-93) and percent
annual change in adult ocean-type chinook salmon
passing four mid-Columbia River dams. Percent annual
change is based on exponential regression of passage
counts against time for two time periods: the entire }
data series (varies by dam), and the most recent
20 years (1974-93). Based on data from the Coordinated
Information System Computerized Distributed System
(Anderson 1994).
Average
Location Run run size Full series Last 20 years
Wells Summer 2,369 2.7 3.3
Fall 938 41.9 +2.0
Both 3,306 71.9 72.2
Rocky Reach Summer 3,810 -4.5 -6.6
Fall 2,091 -2.1 +0.6
Both 5,901 -3.9 -4.8
Rock Island Summer 13,015 +1.7- 0.4
Fall 3,659 +2.8 +8.2
Both 16,674 +1.8 . +1.0
Priest Rapids Summer 14,395 -0.2 -0.8
Fall 10,427 +2.0 +6.3
Both 24,822 +0.6 +1.9





37

Table 2. Continued.

Year of Number

Stock* Hatchery” Agency® Class* Plant Stream* Planted

Bonn ROCK R WDF yearling 84 Columbia R.(V) 226,276
Sn x Pr ROCK R WDF fingerling 84 Columbia R.(V) 533,800
Priest PRIEST WDF fingerling 84 Columbia R. 245,000
Bonn PRIEST WDF fingerling 84 Columbia R. 9,497,701
Sn x Pr ROCK R WDF yearling 8s Columbia R.(V) 253,800
Sn x Pr ROCK R WDF ftingerling 85 Columbia R.(V) 95,500
Priest PRIEST WDF fingerling 85 Columbia R. 6,988,800
Sn x Pr ROCK R WOF yearling 86 Columbia R.(V) 252,268
Priest PRIEST WDF yearling 86 Columbia R. 196,000
Priest PRIEST WDF fingerling 86 Columbia R. 6,363,000
Priest ROCK R WDE yearling 87 Columbia R.(V) 237,467
Wells(F) ROCK R WDF fingerling 87 Columbia R.(V) 247,500
Priest PRIEST WDF fingerling 87 Columbia R. 6,048,000
Wells (F) ROCK R WDF yearling 88 Columbia R. 229,802
Priest PRIEST WDF fingerling 88 Columbia R. 7,709,000
Priest ROCK R WDF yearling 89 Columbia R. 190,000
Priest PRIEST WDF fingerling 69: Columbia R. 5,404,500
Priest ROCK R WDF yearling 90 Columbia R. 230,000
Priest PRIEST WDF fingerling 90 Columbia R. 6,431,100
Wells(F) ROCK R WDF fry 90 Columbia R. 679,800
Wells(F) ROCK R WDF yearling 91 Columbia R. 220,400
Priest PRIEST WDF fingerling 91 Columbia R. 5,239,700
Priest PRIEST WDF fingerling 92 Columbia R. 7,000,100
Priest ROCK R WDF yearling 93 Columbia R. 201,000
Priest PRIEST WDF fingerling 93 Columbia R. 5,451,000
Priest ROCK R WDF fingerling 93 Columbia R. 1,217,601
Wells(F) ROCK R WDF fingerling 93 Columbia R. 304,399

Total = 132,728,561

Yakima River plants - Fall chinook salmon (incomplete records)

Klick KLICK WDF yearling 76 Yakima R. 20,613
unknown unknown fingerling 84 Yakima R. 584,633
Bonn SPRING Fws fingerling 85 Low. Yakima 1,864,155
Bonn LEAV Fws fingerling 86 Low. Yakima .1,690,319
Leav LEAV Fws yearling 87 Low. Yakima 215,126
unknown unknown fingerling 87 Low. Yakima 1,071,589
Priest BUR Fws fingerling 87 Low. Yakima 17,786
Bonn LEAV FWws fingerling 88 Yakima R. 1,574,671
Bonn YAK FWS fingerling 88 Yakima R. 246,012
Bonn SENN Coop fingerling 88 Yakima R. 9,825
unknown unknown fingerling 89 Low. Yakima 1,770,437
unknown unknown fingerling 89 Yakima R. 200,077
unknown unknown fingerling 90 Low. Yakima 1,360,078
unknown unknown fingerling 90 Yakima R. 199,980
unknown unknown fingerling 93 Low. Yakima 751,134

Total = 10,804,688



35

Table 2. Continued.

Year of Number
Stock* Hatchery” Agency Class* Plant Stream® Planted

Okanogan River plants - Summer chinook salmon

Wells ROCK I WDF yearling 91 Similkameen R. 352,600
Wells ROCK I WDF yearling 92 Similkameen R. 542,000
Wells ROCK I WDF yearling 93 Similkameen R. 675,500

Columbia River plants - Summer chinook salmon

Wells WELLS WDF fingerling 68
Wells WELLS WDF fry 68
Wells WELLS WDF fry 69
Wells WELLS WDF fry 70
Wells WELLS WDF fingerling 70
Wells WELLS WDF yearling 71
Wells WELLS WDF fry 7
Wells WELLS WDF unknown 72
Wells WELLS WDF unknown 73
Wells WELLS WDF fingerling 74
Wells WELLS WDF fry 74
Wells WELLS WOF yearling 75
Wells WELLS WDF fingerling 75
Wells WELLS WDF yearling 76
Wells WELLS WDF fingerling 76
Wells WELLS WDF fry 76
Wells WELLS WDF yearling 77
Wells WELLS WDPF fingerling 77
Wells WELLS WDF fry 77
Wells WINT FWS yearling 77
Wells WELLS WDF yearling 78
Wells WELLS WDF fingerling 78
Wells WELLS WDF fry 78
Wells WINT Fws yearling 78
Wells WELLS WDF fingerling 79
Wells WINT FWS yearling 79
Wells WELLS WDF yearling 80
Wells WELLS WDF fingerling 80
Wells ROCK R WDF fingerling 81
Wells WELLS WOF fingerling 681
Wells ROCK R WDF yearling 82
Wells WELLS WDF fingerling 82
Wells ROCK R WDF yearling 83
Wells WELLS WDF fingerling 83
Wells WELLS WDF fingerling 84
Wells WELLS WDF yearling . 85
Wells WELLS WDF fingerling 85
Wells WELLS WDF yearling 86
Wells WELLS WDF fingerling 86
Wells WELLS WDF yearling 87
Wells WELLS WDF fingerling 87
Wells WELLS WDF yearling 88
Wells WELLS WDF fingerling 88

Total = 1,570,100

Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Coluribia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia

61,000
2,077,000
3,443,654
3,074,086

989,700
359,000
1,452,000
2,373,200
2,095,500
875,800
1,575,000
284,700
673,250
155,024
668,390
3,000,904
94,353
$01,879
248,574
311,200
347,104
$52,682
100,000

94,416
2,264,065

77,602

313,883
2,323,963
-(V) 29,547
2,271,652

101,520
2,611,746
.(V) 175,898
1,432,900
1,240,865

186,000
1,549,000

200,440
1,791,617

394,360
1,018,709.

385,213
1,759,933

DAADDDADDADADADDADDDADNADAADNADDNDDADNDDD DAD



60

ecean-type chinook salmon in the tributaries above Rock Island (|
Dam has been relatively small and does not appear to pose a
significant risk factor to these stocks. There has been
substantial hatchery production of fall-run chinook salmon at
Priest Rapids Hatchery, and upriver bright fish from this and

other hatcheries have been planted in the Yakima River.
DISCUSSION AND CONCLUSIONS

A key question in the biological evaluation of MCR late-run
chinook salmon is whether the summer- and fall-run fish in the
MCR are reproductively isolated. Whether they are considered
separately or jointly is pivotal in determing the ESU and its
numeric stability. We have evaluated a variety of biological

characters and have summarized them in Table 7.

Reproductive Isolation
The petitioners argue that MCR summer chinook salmon are
reproductively isolated with respect to three other groups of
chinook salmon within the Columbia River Basin: 1) Snake River
summer chinook salmon, 2) mid-Columbia River spring chinook

salmon, and 3) mid-Columbia River fall chinook salmon.

Genetic Characters

Genetic data based on protein electrophoresis are consistent
with the existing view of the genetic affinities in MCR summer
chinook salmon. This group of fish is clearly reproductively
isolated from Snake River summer chinook salmon (previously

determined by NMFS to be part of a different ESU), and from the



BE
5
into ESA threshold considerations for Pacific salmon. However,
available PVA models generally require substantial life-history
information that is not available for most Pacific salmon
populations, so quantitative PVA is not practical at this time.
Therefore, NMFS considers a variety of information in

evaluating the level of risk faced by an ESU. Important factors
include 1) absolute numbers of fish and their spatial and I
temporal distribution; 2) current abundance in relation to

historical abundance and carrying capacity of the habitat;

3) trends in abundance, based on indices such as dam or redd |
counts or on estimates of spawner-recruit ratios; 4) natural and
human-influenced factors that cause variability in survival and |
abundance; 5) possible threats to genetic integrity (e.g.,

selective fisheries and interactions between hatchery and |

naturally-produced fish); and 6) recent events (e.g., a drought,
a change in management procedure, or improvements in mainstem

passage) that have predictable short-term consequences for

abundance of the ESU.

In evaluating these factors, the role of artificial
Propagation is an important issue. Because of the ESA’s emphasis
on conserving species in their native ecosystems, threshold
determinations must focus on the status of natural fish, on the
premise that an ESU is not healthy unless a viable population
exists in the natural habitat.

Artificial production may have direct or indirect impacts on
the status of a population through direct supplementation of

numbers, by altering the genetic composition of the population,


a

4a7

0.1000 © 0.0667. 0.0333 0.0000
heen adennndaccnhoccotone .

WANFORD REACH FA
PRIEST RAP. H. FA
YAKIMA FA
WENATCHEE SU
WELLS H. SU
STHELKAMEEN SU
BONNEVILLE H. FA
L.W. SALMON H. FA
LYONS FERRY H. FA
MARION ORAIN FA E
DESCHUTES FA
Lo sano FA j
———-———-_ WINTHROP H. SP q
| CARSON H. SP |
LEAVENWORTH H. SP |
NASON SP
CHIWAWA SP
| JOHN DAY SP
YAKIMA SP
WHITE SP
HOUND BUTTE K. SP
p———-————— AMERICAN SP

Li. NACHES/L.HAC/BMP. SP

+ ors
0. 200 “7. i667 7 i333 0. i000 ay 0867 wy 0333 0.0000

CAVALLI-SFORZA & EDWARDS (1967) CHORD DISTANCE

Figure 3. Genetic relationships among selected samples of
chinook salmon in the Columbia River Basin based on
Cavalli-Sforza and Edwards (1967) chord distance and
UPGMA clustering for 36 loci (Marshall 1994a and b).
Same loci and samples as Figure 2. SP = spring-run,
sU = summer-run, and FA = fall-run.



53

——@— Wenatchee River
++ a - + Methow River
—t—~ Okanogan River
++ © -+Similkameen River

1955 1960 1965 1970 1975 1980 1985 1990 1995

Year

Figure 4. Ocean-type chinook salmon redd counts (expanded aerial
counts) for the Wenatchee, Methow, Okanogan, and
Similkameen Rivers, 1956-93. Data from Chapman et al.
(1994, appendix D-2).



7

Life history--The petitioners described MCR summer chinook
salmon as reproductively isolated from Snake River summer chinook
salmon by differences in migration, spawning, and rearing times,
as well as by geographic separation. They noted that NMFS
determined that the two summer chinook salmon stocks were
reproductively isolated in 1992 (NEDC et al. 1993, p. 7-8).

Genetics--NEDC et al. (1993, p. 8) cited a protein
electrophoretic study by Hershberger et al. (1988) to show that
spring-run and summer-run chinook salmon in the MCR were
separated into two genetic clusters. The petitioners stated that
there is little available genetic information comparing summer
and fall chinook salmon populations in the MCR (NEDC et al. 1993,
p. 8), and that this lack of scientific data supports keeping
these stocks separate.

The petitioners also claimed that fall chinook salmon in the
MCR were historically considered "inferior" to summer chinook
salmon (NEDC et al. 1993, p. 8). The Okanogan River was said to
contain the only documented native stock of summer chinook salmon
in the MCR (NEDC et al. 1993, p. 6). According to the
petitioners, the legacy of the race of summer chinook salmon that
migrated past the site of what is now Grand Coulee Dam was
partially preserved by the Grand Coulee Fish Maintenance Project

(NEDC et al. 1993, p. 2).



Or ea,

wt
By

NOAA Technical Memorandum NMFS-NWFSC-22

Status Review

for

Mid-Columbia River
Summer Chinook Salmon

F. William Waknitz, Gene M. Matthews,
Thomas Wainwright, and Gary A. Winans

National Marine Fisheries Service

Northwest Fisheries Science Center

Coastal Zone and Estuarine Studies Division
2725 Montlake Blvd. E., Seattle, WA 98112

July 1995

U.S. DEPARTMENT OF COMMERCE
Ronald H, Brown, Secretary

National Oceanic and Atmospheric Administration
D. James Baker, Administrator

National Marine Fisheries Service
Rolland A. Schmitten, Assistant Administrator for Fisheries



28

We found no empirical evidence indicating that a unique
population of massive fish ever existed in the Columbia River.
Historical accounts from the early 1800s suggested chinook salmon
caught by aboriginal people in the upper Columbia River at Kettle
Falls averaged about 7.0 kg in weight (Mullan et al. 1992b) .

Wild adult ocean-type fish sampled at Rock Island Dam in 1940
weighed about 8.0 kg (Fulton and Pearson 1981): From historic
catch records, Beiningen (1976) estimated a mean weight for
"summer-run" chinook salmon of 8.5 kg, while Chapman (1986) used
a mean weight of 10.5 kg in his estimates of population abundance
for the late-1800s. On the other hand, early settlers of the
upper Columbia River were said to have witnessed "summer-run"
adult fish averaging 18.0 kg (Bryant and Parkhurst 1950). These
anecdotes must be considered with caution, since’ no weights were
actually reported and scale analysis was not available to
determine juvenile life histories.

Considering that the size of the ancestral Columbia River
chinook salmon population has been estimated at 2-4 million fish
(Ebel et al. 1989), very large chinook salmon were undoubtedly
common in the past. A few are occasionally observed today. As
noted earlier, the ancestral chinook salmon run peaked in the
lower river in early summer and was represented by many spawning
populations of both stream- and ocean-type fish from upper
tributaries in the Columbia and Snake Rivers. Therefore, it is
possible that June hogs were simply the largest members of many
different spawning populations. By the early 1900s, overfishing

had largely extirpated the majority of Columbia River chinook



70

Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the
Columbia River and its tributaries: Area 111, Washington
streams from the Klickitat and Snake Rivers to Grand Coulee
Dam, with notes on the Columbia and its tributaries above
Grand Coulee Dam. U.S. Fish. Wildl. Serv. Spec. Sci. Rep.
Fish. 37:1-108. .

Burner, C. J. 1951. Characteristics of spawning nests of
Columbia River salmon. U.S. Fish. Wildl. Serv. Fish. Bull.
52:97-110.

Busack, C. 1990. Yakima/Klickitat production project genetic
risk assessment. Appendix A, Yakima/Klickitat production
project preliminary design report, 20 p. (Available
Bonneville Power Administration, P.O. Box 3621, Portland, OR
97208-3621.)

Castoldi, P. 1983. A detailed listing of the liberations of
salmon into the open waters of the state of Washington
during 1982. Wash. Dep. Fish. Prog. Rep. 185:1-380.

Castoldi, P., and T. Rasch. 1982. A detailed listing of the
liberations of salmon into the open waters of the state of
Washington during 1981. Wash. Dep. Fish. Prog. Rep.
160:1-339.

Cavalli-Sforza, L. L., and A. W. F. Edwards. 1967.
Phylogenetic analysis: Models and estimation procedures.
Evolution 21:550-570.

Chapman, D. W. 1986. Salmon and steelhead abundance in the
Columbia River in the nineteenth century. Trans. Am. Fish.
Soc. 115:662-670.

Chapman, D. W. 1989. Critical review of variables used to
define effects of fines in redds of large salmonids. Trans.
Am. Fish. Soc. 117:1-21,

Chapman, D. W., J. M. Van Hyning, and D. H. Mckenzie. 1982.
Alternative approaches to base run and compensation goals
for Columbia River salmon and steelhead resources. Report
for Chelan County, Grant County, and Douglas County Public
Utility Districts by Battelle Pacific Northwest Laboratory,
Richland, Washington. (Available Don Chapman Consultants,
3653 Rickenbacker, Ste. 200, Boise, ID 83705.)

Chapman, D., A. Giorgi, M. Hill, A. Maule, S. McCutcheon, D.
Park, W. Platts, K. Pratt, J. Seeb, L. Seeb, and F. Utter.
1991. Status of Snake River chinook salmon. Final report
submitted to ESA Administrative Record for Snake River
chinook salmon, 531 p. plus Appendix. (Available Pacific
Northwest Utilities Conference Commission, 101 SW Main
Street, Portland, OR 97204.)



whose juveniles migrate to sea as subyearlings, known as "ocean-
type" populations; and those whose juveniles migrate to sea as
yearlings, designated as "stream-type" populations (Gilbert 1912,
Taylor 1990, Healey 1991). Ocean-type chinook salmon in the MCR
Basin spend most of their ocean life in coastal waters, returning
to fresh water a few months prior to spawning. Stream-type fish,
on the other hand, perform extensive offshore migrations,
returning to fresh water many months prior to spawning (Healey
1991).

A strong tendency toward one or the other of these types is
also found within most chinook salmon populations outside the
MCR. Ocean-type populations dominate the southern range of the
species from California through the coastal streams of Oregon and
Washington, and stream-type fish dominate the range from
approximately 56° N in British Columbia through Alaska (Taylor
1989, Healey 1991). However, in the southern portion of its
range, stream-type chinook salmon are relatively common in
upstream areas of most large rivers, while small rivers contain
primarily ocean-type fish. Stream-type populations also appear
to predominate in Asian representatives of the species (Healey
1991).

Variations in stream temperature regimes due to latitude or
altitude appear to be the major factor controlling the general
distribution of the two types. However, Healey (1983) suggested
that other factors, such as distance of the spawning migration,
annual river-discharge cycles, and ocean migration patterns may

also be important.



NOAA Technical Memorandum NMFS

The National Marine Fisheries Service's Northwest Fisheries Science Center uses
the NOAA Technical Memorandum series to issue informal scientific and technical
Publications when complete formal review and editorial processing are not
appropriate or feasible due to time constraints. Documents within this series
reflect sound professional work and may be referenced in the formal scientific and
technical literature.

The NMFS-NWFSC Technical Memorandum series of the Northwest Fisheries
Science Center continues the NMFS-F/NWC series established in 1970 by the

Northwest Fisheries Center. The NMFS-AFSC series is now being used by the
Alaska Fisheries Science Center.

This document should be cited as follows:

Waknitz, F. W., G. M. Matthews, T. Wainwright, and G. A. Winans. Status
review for mid-Columbia River summer chinook salmon. U.S. Dep. Commer.,
NOAA Tech. Memo. NMFS-NWFSC-22, 80 p.

Reference in this document to trade names does not imply endorsement by the
National Marine Fisheries Service, NOAA.



40
River did not recover during the same period, as screening of
irrigation diversions was not obligatory in that system (Robison
1957). ,

All adult fish passing Rock Island Dam from 1939 to 1943
were taken either to USFWS hatcheries on the Wenatchee or Methow
Rivers for artificial spawning or to fenced reaches of the
Wenatchee or Entiat River for natural spawning. Juveniles
derived from adults of mixed-stock origin crossing Rock Island
Dam were reared at USFWS hatcheries and transplanted into the
Wenatchee, Methow, and Entiat Rivers.

Fish trapping operations began in May 1939 and continued
through late fall each year until 1943. A total of five complete
brood years were affected. Early-run fish (stream type) were
treated separately from late-run fish (ocean type), and few
distinctions were made regarding either "summer" or "fall"
components of the late run, as all late-run fish were captured.

Fish and Hanavan (1948) estimated that 20 to 34% (mean =
27%) of the fish passing Rock Island Dam each year were, by
present day standards, "fall-run" chinook salmon (i.e., crossed
Rock Island Dam after 20 August). Because the GCFMP continued
for 5 years and used all late-run fish, including those destined
for now-inaccessible spawning areas in British Columbia, all
present day ocean-type chinook salmon above Rock Island Dam are
the progeny of the mixture of chinook salmon collected at Rock
Island Dam from 1939 to 1943.

The only MCR tributary that ‘did not receive spawning adults

or mixed-stock hatchery juveniles during the 5-year GCFMP was the



24
7.5%. Six-year-old fish were rare, comprising less than 0.5% of
the return (Mullan 1987). The overall age values were similar to
area-specific values documented for wild upriver brights in the
Deschutes (CBFWA 1990) and Snake Rivers (Chapman et al. 1991) and
in the Hanford Reach of the Columbia River (Dauble and Watson
1990). Regarding age structure, mainstem Yakima River ocean-type
chinook salmon were considered typical of chinook salmon in the
Hanford Reach of the Columbia River (Busack 1990).

In upriver bright populations, all 2-year-old and most
3-year-old fish were males, whereas females predominated the
older age classes (Howell et al. 1985, Dauble and Watson 1990).
Overall, males slightly outnumbered females.

Fecundity data are not available for wild summer-run fish.
At Wells Dam Hatchery (summer-run fish), fecundity averaged
4,935 eggs per female between 1967 and 1970, and at Priest Rapids
Hatchery (fall-run fish), fecundity averaged 4,704 eggs from 1978
to 1992 (Howell et al. 1985). For fall-run chinook salmon
utilizing artificial spawning channels in the MCR, Mathews and

Meekin (1971) observed a mean fecundity of 5,015 eggs.

Ocean Distribution

Information on the ocean distribution of wild chinook salmon
populations from the Columbia River Basin is limited (Waples
et al. 1991, Matthews and Waples 1991). However, hatchery fish
have received coded wire tags for over two decades, and catches
of these fish provide some general insight into oceanic migratory
patterns. Seven consecutive broods of Snake River ocean-type

chinook salmon consistently displayed a more southerly oceanic



33

Table 2. Hatchery plants of ocean-type chinook salmon into the
mid-Columbia River and its tributaries. From Coleman
and Rasch 1981; Castoldi 1983; Castoldi and Rasch 1982;
Hill 1984; Kirby 1985; Abrahamson 1986, 1987, 1988;
Mullan 1987; Yakima Indian Nation 1994; and Chapman
et al. 1994). Abbreviations are given below.
Year of Number
Stock* Hatchery” Agency® Class Plant Stream® Planted
Entiat River plants - Summer chinook salmon
GCFMP LEAV FWS fingerling* 41 Entiat R. 640,800
GCFMP ENT FWS unknown 41 Entiat R. 150,000
GCFMP LEAV FWS fingerling* 42 Entiat R. 85,500
GCFMP ENT Fws unknown* 42 Entiat R. 50,400
GCFMP ENT Fws fingerling 43 Entiat R. 55,900
GCFMP ENT Fws unknown* 44 Entiat R. 24,900
GCFMP ENT FWS unknown 4s Entiat R. 25,700
Methow ENT FWS yearling 45 Entiat R. 27,700
Carson ENT FWS yearling 45 Entiat R. 8,200
Entiat ENT Fws yearling 46 Entiat R. 192,400
Entiat ENT FWS unknown 46 Entiat R. 22,300
Entiat ENT FWS fingerling 47 Entiat R. 251,400
Entiat ENT FWS fingerling 49 Entiat R. 235,200
Entiat ENT FWS fingerling 50 Entiat R. 432,600
Entiat ENT FWwS fingerling S51 Entiat R. 488,500
Entiat ENT FWS unknown 51 Entiat R. 110,300
Entiat ENT FWS fingerling 48 Entiat R. 396,700
Entiat ENT FWws fingerling 52 Entiat R. 281,000
Entiat ENT FWSs fingerling 53 Entiat R. 404,500
Entiat ENT FWS yearling 53 Entiat R. 254,600
Entiat ENT FWwSs yearling 54 Entiat R. 212,000
Entiat ENT FWS fingerling 55 Entiat R. 228,800
Entiat ENT Fws yearling 55 Entiat R. 212,000
Entiat ENT FWS yearling 56 Entiat R. 250,500
Entiat ENT FWS fingerling 57 Entiat R. 32,900
Entiat ENT FWS yearling 57 Entiat R. 273,900
Entiat ENT FWwS fingerling 58 Entiat R. 251,300
Entiat ENT FWs yearling 58 Entiat R. 137,500
Entiat ENT FWS fingerling 59 Entiat R. 522,500
Entiat ENT FWS yearling 60 Entiat R. 143,800
Entiat ENT FWs yearling 61 Entiat R. 152,300
Entiat ENT FWS yearling 62 Entiat R. 316,500
Entiat ENT Fws yearling 63 Entiat R. 229,800
Entiat ENT Fws fingerling 64 Entiat R. 230,100
Sprng Cr. ENT FWS fingerling 64 Entiat R. 990,800
Wells ENT FWS yearling 76 Entiat R. 294,000
Total = 8,617,300
Methow River plants - Summer chinook salmon
GCFMP LEAV Fws fingerling* 41 Methow R 182,000
GCFMP WINT FWws fingerling 43 Methow R. 66,600
GCFMP WINT FwS fingerling 44 Methow R. 10,600
Entiat WINT FWS fingerling 46 Methow R. 480,600



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variation, controlled primarily by elevation, is thought to be
the key factor influencing the run and spawn timing of ocean- and
stream-type populations. In most cases, stream-type chinook
salmon spawn earlier, at higher elevations, and further upstream
than ocean-type chinook salmon.

Spawning fish of both types use the upstream portions of
their respective spawning areas first and the downstream portions
last, thus providing opportunities for mixing among groups of
fish whose spawning activities overlap spatially and temporally
(i.e., spring- and summer-run fish in the Snake River and summer-
and fall-run fish in the Columbia River). This phenomenon in the
MCR is succinctly described by Mullan (1987, p. 3): "This time-
space dimension was originally filled by successive waves of
chinook salmon spawners."

In the Columbia River, adult chinook salmon migrating
upstream past Bonneville Dam from March through May, June through
duly, and August through October have been categorized as
spring-, summer-, and fall-run fish, respectively (Burner 1951).
However, run-partitioning dates are progressively later at each
dam encountered as adult fish migrate upstream. While annual
run-partitioning dates remain static at all dams, adult migration
timing varies annually, with water temperature as the primary
controlling factor. Moreover, to some degree, the middle portion
of the run (i.e., summer-run chinook salmon) is overlapped early
in the migration by the spring-run and later by the fall-run.

Therefore, the separation of Columbia River chinook salmon

into three races, based principally on adult run-timing at dams,



a a ee og peg en pea na eee eae



3
in the NMFS "Definition of Species" paper (Waples 1991). The
NMFS policy stipulates that a salmon population (or group of
populations) will be considered "distinct" for purposes of the
ESA if it represents an evolutionarily significant unit (ESU) of
the biological species.

An ESU is defined as a population that 1) is substantially
reproductively isolated from conspecific populations and
2) represents an important component in the evolutionary legacy
of the species (Waples 1991). Information that can be useful in
determining the degree of reproductive isolation includes
incidence of straying, rates of recolonization, degree of genetic
differentiation, and physical or ecological barriers to
migration. Insight into evolutionary significance can be
provided by data on genetic and life-history characteristics,
habitat differences, and the effects of stock transfers or

supplementation efforts.
Hatchery Fish and Natural Fish

Because artificial propagation of Pacific salmonids has been
widespread for many years, the influence of hatchery fish must be
considered in most ESA status reviews. NMFS policy stipulates
that in determining whether a population is distinct for purposes
of the ESA, attention should focus on "natural" fish, which are
defined as the progeny of naturally spawning fish (Waples 1991).
This approach directs attention to fish that spend their entire
life cycle in natural habitat and is consistent with the mandate

of the ESA to conserve threatened and endangered species in their



55

30,000 + = —t—Total Ocean Type }

20,000

15,000

Aduit Count

10,000

5,000

Figure 5. Counts of adult ocean-type chinook salmon passing Rock Island Dam, 1933-93.
Based on data from Mullan (1987; counts for 1933-59) and the Coordinated
Information System Computerized Distributed System (Anderson 1994; counts for
1960-93).



71

Chapman, D., A. Giorgi, T. Hillman, D. Deppert, M. Erho,
S. Hays, C. Peven, B. Suzumoto, and R. Klinge. 1994.
Status of summer/fall chinook salmon in the mid-Columbia
region. 412 p. plus Appendicies. Report for Chelan,
Douglas, and Grant County PUDs. (Available Don Chapman
Consultants, 3653 Rickenbacker, Ste. 200, Boise, ID 83705.)

Coleman, P., and T. Rasch. 1981. A detailed listing of the
liberations of salmon into the open waters of the state of
Washington during 1980. Wash. Dep. Fish. Prog. Rep.
132:1-360.

Columbia Basin Interagency Committee (CBIC). 1957. Inventory of
streams and proposed improvements for development of the
fishery resource of the Columbia River Basin--Part II.
Columbia River Basin Fishery Program, 100 p. (Available
Environmental and Technical Services Division, Natl. Mar.
Fish. Serv., 525 N.E. Oregon Street, Portland, OR 97232).

Columbia Basin Fish and Wildlife Authority (CBFWA). 1990.
Integrated system plan for salmon and steelhead production
in the Columbia River Basin, 449 p. (Available Northwest
Power Planning Council, 851 S.W. Sixth, Suite 1100,
Portland, OR 97204-1348.)

Craig, J. A., and A. J. Suomela. 1941. Time of appearance of
the runs of salmon and steelhead trout native to the
Wenatchee, Entiat, Methow, and Okanogan Rivers. Cited in
J. W. Mullan, K. R. Williams, G. Rhodus, T. W. Hillman, and
J. D. McIntyre (editors), 1992, Production and habitat of
salmonids in mid-Columbia River tributary streams. U.S.
Fish Wildl. Serv. Monograph I:J358-J380.

Dauble, D. D., and D. G. Watson. 1990. Spawning and abundance
ef fall chinook salmon (Oncorhynchus tshawytecha) in the
Hanford Reach of the Columbia River, 1948-1988. Report to
U.S. Dep. Energy, Contract DE-AC06-76RLO 1830, 52 p.
{Available Office of Scientific and Technical Information,
P.O. Box 62, Oak Ridge, TN 37831.)

Davidson, F. A. 1953. Historical notes on development of Yakima
River Basin. Wash. Dep. Fish., unpubl. manuscr., 21 p.
(Available Washington Department of Fish and Wildlife, 600
Capitol Way N., Olympia, WA 98501-1091.)

Dennis, B., P. L. Munholland, and J. M. Scott. 1991.
Estimation of growth and extinction parameters for
endangered species. Ecol. Monogr. 61:115-143.

Ebel, W. J., C. D. Becker, J. W. Mullan, and H. L. Raymond.
1989. The Columbia River--Toward a holistic understanding.
In D. P. Dodge (editor), Proc. Int. Large River Symp. Can.
Spec. Publ. Fish. Aquat. Sci. 106:205-219.



41

Okanogan River (Fish and Hanavan 1948, Mullan et al. 1992b). All
chinook salmon adults destined for the Okanogan River from 1939
to 1943 were intercepted and either forced to spawn in other
tributaries or in one of the USFWS hatcheries.

As none of the progeny of GCFMP fish were planted in the
Okanogan River during this 5-year period, the native population
of ocean-type chinook salmon in the Okanogan River was virtually
eliminated. It is possible that 6-year old adults returned in
1944, thereby escaping the effects of GCFMP; but the low
frequency of this age class (<1%) in Columbia River chinook
salmon populations makes this an unlikely event. The ocean-type
chinook salmon now observed in the Okanogan River are likely the
progeny of mixed-stock strays from other tributaries or from the
mainstem Columbia River. These strays must have’ repopulated the

Okanogan River after termination of the GCFMP.

Artificial Propagation

Hatchery efforts with ocean-type chinook salmon in the MCR
have been continuous and intensive since the implementation of
the GCFMP. Three USFWS hatcheries were established during the
GCFMP, and six Washington Department of Fisheries facilities have
been constructed since then (Table 3). Currently, only the
Leavenworth and Entiat facilities are not rearing ocean-type
chinook salmon. As noted above, by 1944, all MCR chinook salmon
were essentially the progeny of relocated stock (Fish and Hanavan
1948). Since 1941, over 200 million ocean-type chinook salmon

have been released into the MCR Basin as either 0-age or yearling



43
fish (Table 2). Only approximately 6.2 million (~3.0%) of these

fish were from stocks outside the MCR Basin.

Phenotypic Characteristics

Variation in phenotypic characteristics of chinook salmon in
the Columbia River Basin was evaluated in a multivariate study by
Schreck et al. (1986), who examined meristic and morphometric
variation in 56 samples of ocean- and stream-type chinook salmon.
Previous analysis of 20 trusslike morphometric characters had
shown that fish with similar life histories tended to have
similar body shapes (Winans 1984). Schreck et al. (1986) also
found that ocean-type fish from the MCR grouped together (both
“fall-run" and “summer-run"), and stream-type fish from the Snake
River in Idaho grouped together (both “spring-run" and "summer-
run").

In the same study, a multivariate analysis of nine meristic
characters revealed two major groups in the Columbia River Basin.
The first group contained stream-type chinook salmon from west of
the Cascade Mountains and all ocean-type chinook salmon from the
MCR. The other group contained stream-type chinook salmon from
east of the Cascade Mountains and stream-type chinook salmon from
Idaho. For all but one of the meristic characters analyzed,
results indicated that between-year variability did not account

for substantial levels of variation among stocks.



‘information, is presented following this section. The

|
6

er through ecological interactions (competition, predation,

disease transmission, etc.) between artificially-produced and

natural fish. A mixture of artificially-produced and natural

fish in a population also complicates assessment of the natural

fish: abundance and viability of the natural stock is difficult

to estimate unless artificially-produced fish are clearly marked,
and abundance trends in the natural stock can be obscured by the

infusion of artificially-produced fish and their progeny into the

natural population.
SUMMARY OF PETITIONERS’ CLAIMS

This section summarizes declarations made in the petition by
the Northwest Environmental Defense Center and others (NEDC
et al. 1993) to support the designation of mid-Columbia River
(MCR) summer-run chinook salmon as an ESU. Information regarding

the assertions of the petitioners, as well as additional relevant

petitioners’ arguments and other relevant information are
evaluated in the Discussion and Conclusions section of this

review.

Reproductive Isolation
Geographic Isolation
Homing fidelity--The petitioners stated that MCR summer a
chinook salmon have a reduced likelihood of straying due to
specificity of the homing instinct and the long migration to the

spawning grounds (NEDC et al. 1993, p. 7).