The Analysis of Shell Growth and Age at Harvest of the Butter Clam (Saxidomus
giganteus Deshayes): An Insight to the Implementation of Management Practices at the
Qwu?gwes Archaeological Site (45TN240) in Olympia, WA, USA.
by
Jennifer L. Hurst
520021015
A Dissertation Presented to the Department of Archaeology and Geography
University of Exeter
In Partial Fulfillment
Of the Requirements for the Degree
Master of Arts
September 2003
Abstract
The Analysis of Shell Growth and Age at Harvest of the Butter Clam (Saxidomus
giganteus Deshayes): An Insight to the Implementation of Management Practices at the
Qwu?gwes Archaeological Site (45TN240) in Olympia, WA, USA.
by
Jennifer L. Hurst
The Qwu?gwes archaeological site was once a prehistoric village to the ancestors of the
Squaxin Island Tribe nearly 500 years ago [based upon the 470BP 14C dating of an
associated wooden fishtrap stake (D. Croes pers. comm., 2003)], in Olympia, WA, USA.
The four years of seasonal excavation at the archaeological site has produced thousands
of organic and inorganic artifacts preserved primarily in waterlogged conditions,
including wooden fibers, basketry, cordage, bones, lithics, and over 70,000 individual
marine shells. The absolute abundance of the preserved shellfish indicates the
importance of the natural resource to the past inhabitants of the site. However, whether
these natural resources were purely exploited on an as-need basis or rather, were
strategically harvested in the attempts to preserve the molluscan populations for future
resource, remains to be investigated.
The primary aim of this study is to highlight the potential evidence for shellfish
management strategies implemented at the Qwu?gwes archaeological site by the analysis
and investigation of the preserved shellfish remains, via the analysis of the shell growth
attained before harvest and the external annuli, to determine the age at which the clams
were harvested. It is hoped suggestion can then be offered to the likely probability of the
implementation of direct management strategies by the past inhabitants of Qwu?gwes.
The results of the analyses suggest 87% of the clam shells had attained lengths within the
range of 60-95mm implying that only those shells which had acquired adequate growth
were selected for harvest. Further analysis of the growth rings from the Qwu?gwes
assemblages through age at harvest studies support this suggestion, as 71.23% of the
population had developed between 7-9 growth rings before harvest. Similar length
measurements have been observed at Kiket Island, WA (Houghton 1973), and were
determined to require 8 years of growth in order to establish the measured length,
suggesting similar temporal allotments were required at Mud Bay. Overall, the collective
analyses support the suggestion that the shells were systematically harvested at Mud Bay
perhaps on a rotational schedule, only shellfishing on the beaches every 8 years; or only
selecting those clams that were at least 8 years old and re-depositing the younger, smaller
clams to promote further growth.
.
3
Table of Contents
List of Figures ............................................................................................................................................... ii
List of Tables................................................................................................................................................ iii
List of Tables................................................................................................................................................ iii
Chapter 1. Introduction .............................................................................................................................. 1
Chapter 2. Site location............................................................................................................................... 3
Cultural significance and environmental background................................................................................ 3
The climate of the southern Puget Sound .................................................................................................. 9
Chapter 3. The biology and physiology of the butter clam ..................................................................... 10
Chapter 4. Analysis of shell growth ......................................................................................................... 13
The ancient shellfish assemblage............................................................................................................. 15
The modern shellfish assemblage ............................................................................................................ 19
Chapter 5. Age at harvest (growth-line analysis).................................................................................... 24
Chapter 6. Results ..................................................................................................................................... 28
Analysis of shell growth .......................................................................................................................... 28
Age at harvest results............................................................................................................................... 34
Chapter 7. Discussion................................................................................................................................ 36
Chapter 8. Conclusions ............................................................................................................................. 42
Bibliography................................................................................................................................................ 43
Appendix ..................................................................................................................................................... 46
i
List of Figures
Figure 1: Site Location of Qwu?gwes archaeological site (45TN240), in Olympia
Washington, USA. .................................................................................................................. 3
Figure 2: Location of excavated units mentioned in the text, in relation to the layout of the
site........................................................................................................................................... 5
Figure 3: Relative frequency of the primary shellfish species collected from the Qwu?gwes
archaeological site................................................................................................................... 6
Figure 4: Mud Bay has been extensively exploited for its natural resources for thousands of
years. This picture was taken in the 1940's depicting the exploitation of the Olympia
oyster from the waters of Mud Bay ........................................................................................ 8
Figure 5: The butter clam, with bivalve terminology commonly used throughout study. ............ 10
Figure 6: Alignment of measurements taken to determine the shell length and height of butter
clams from the modern and ancient assemblages. ................................................................ 16
Figure 7: Scatter plot displaying the shell length and height measurements; highlighting the
abundance of shells ranging from 60-95mm in length. ........................................................ 18
Figure 8: Overall distribution patterning of the butter clam assemblages, in regards to
excavated depth..................................................................................................................... 19
Figure 9: Location of Qwu?gwes and the modern sampled sites in the southern Puget Sound
referenced throughout this study........................................................................................... 22
Figure 10: The growth lines of the ancient butter clams were isolated in the attempts to
further support the growth analysis. Annulus, such as the one the arrow is pointing to,
were identified and counted to determine the shells approximate age before harvest.......... 26
Figure 11: Frequencies of butter clam length measurements of the modern and ancient
assemblages………………………………………………………………..……………29
Figure 12: Standard deviation of shell length measurements from the modern and ancient
clam assemblages, expressing the extreme largest, smallest and average measurements. ... 30
Figure 13: Overall growth line frequencies from the Qwu?gwes butter clam assemblages.
Shells attaining 7-9 annuli before death represent 71.23% of the entire sampled
population. ............................................................................................................................ 35
Figure 14: Ranges of water temperature recorded by the Washington State Department of
Ecology in 1996 and 1997 from the adjacent Budd Inlet. The most successful
temperature for butter clam reproduction, 15°C, is highlighted ........................................... 40
ii
List of Tables
Table 1: Reported shell lengths and the duration of shell accumulation from various locations
along the Northwest Coast. ................................................................................................... 32
iii
Acknowledgements
I would particularly like to thank Dale Croes of the South Puget Sound Community
College who initially suggested I study the Qwu?gwes shellfish and has provided
continuous guidance and support throughout all of my research. Are Strom of the
Washington Department of Fish and Wildlife, Point Whitney, graciously provided the
modern shell measurements collected from several sites within the Puget Sound. Finally,
I would like to thank my advisor, Alan Outram of the University of Exeter, who offered
much discussion and suggestion in the support of this project.
Many of my friends and family greatly offered moral and financial support leading up to
and during the completion of my graduate work. Of special importance is the
encouragement and support of my parents and grandparents who kept me driven and
focused throughout all of my academic endeavors. Moreover, I could not forget to
declare my gratitude to my good friend, Jennifer Godsill, who has maintained my sanity
and balance.
iv
Dedication
This report is dedicated to my husband, Scott Chambers, for his years of constant support
and selflessness.
Thank you
v
Chapter 1. Introduction
At many coastal archaeological sites, the discovery of marine mollusc remains preserved
within the archaeological record is a common occurrence. For thousands of years,
shellfish have been utilized for sustenance, bait, decoration and tools by people in
antiquity. Coupled with the well preservation and plentiful abundance of shells
remaining from the past, suggestion is offered to the extensive exploitation and
importance of shellfish resources at numerous geographical locations worldwide.
In general, archaeological shell assemblages have been considered an accurate
representative of palaeoenvironments and, thus, may potentially offer suggestion to
possible changes the local environment endured over time (Peacock 2000, 3). The
remains of shells have often received great attention by archaeologists in the attempts to
reconstruct; palaeoenvironmental conditions (e.g. Claassen 1998), nutritional and caloric
potential (e.g. Russo 1991, 205; Buchanan 1988; Collier and Hobson 1987; Wessen
1983), depositional patterning (e.g. Koike 1979), the season in which the shellfish
assemblages were harvested (e.g. Milner 2002b), as well as, potential management
regimes of the local shellfish resources; all of which are instigated to offer suggestion to
the social and economic conditions of a past community.
The primary aim of this study is to highlight the potential evidence for shellfish
management strategies implemented at the Qwu?gwes archaeological site by the analysis
and investigation of the preserved shellfish remains. Examination of the growth
patterning of the butter clam (Saxidomus giganteus Deshayes), via measurement of the
established shell growth acquired before death and the counting of the external annuli, is
employed to offer suggestion to a conscientious attempt by the inhabitants of Qwu?gwes
at managing the local shellfish resources. Results from the analysis of the archaeological
assemblage are, subsequently, compared to three modern butter clam assemblages
collected from the southern Puget Sound, to provide a controlled study of analysis.
1
It is hoped the results of this report will significantly contribute to the current knowledge
of the social, cultural and economic relationships between shellfish and past civilizations;
as well as, reinforce the value of this preserved resource to the archaeological field in the
reconstruction of the past. By highlighting the past management of the natural
environment, suggestion to the conscious and continual exploitation of the local resources
at the site can be offered. Further, the results have the potential to extend beyond the
reconstruction of the past, by further developing the present understanding of modern
butter clam development on the local and regional level – ultimately, contributing to the
management of shellfish resources in commercial and private industries today. Firstly,
the description of the location and environmental background of the Qwu?gwes
archaeological site is detailed, followed by the biology and ecology of the butter clam
which details the physical and environmental tolerances of the species, as well as, the
description of the clam’s physical characteristics. The following chapters on shell growth
analysis and the age at harvest study entails the detailed sampling procedures and
methodologies applied, in the attempts to determine the possibility of management
practices at Qwu?gwes. Finally, the results and conclusions of the overall study will be
discussed and analyzed in detail, in the subsequent chapters.
2
Chapter 2. Site location
The Qwu?gwes archaeological site (45TN240) is located at the southernmost extent of
the Puget Sound; on Mud Bay, in Eld Inlet, on the Northwest Coast of Washington State,
USA (Figure 1). In the summer of 1999, excavation at Qwu?gwes was initiated because
of the imposing endangerment of coastal erosion to the raised shoreline that had begun to
expose the preserved remains of its cultural past. In a joint effort between the South
Puget Sound Community College (SPSCC) and the Squaxin Island Tribe, efforts were
imposed to recover the cultural remains threatened by the destruction of the erosion.
Ironically, the same natural environment that had initiated the excavation and subsequent
analysis of Qwu?gwes, has also been the primary contributor to the excellent waterlogged
preservation of the archaeological site.
Figure 1: Site Location of Qwu?gwes archaeological site (45TN240), in Olympia Washington, USA.
Cultural significance and environmental background
At least, 500 years ago, Qwu?gwes was the site of an ancient village to the ancestors of
the Squaxin Island Tribe [based upon the 470BP 14C dating of an associated wooden
fishtrap stake (Croes and Foster 2003, 1; Foster and Croes 2003, 33)]. The four years of
3
seasonal excavation at the archaeological site has produced thousands of organic and
inorganic artifacts, including; wooden fibers, basketry, cordage, netting, bones, lithics,
and marine and terrestrial molluscs. The excellent preservation of the site has been
greatly influenced by the waterlogged conditions of the twice daily tidal inundations,
coupled with freshwater runoff from the nearby underwater aquifer spring. Largely, the
artifacts and features discovered at the site have led to the suggestion the area was
extensively exploited for the local natural resources of fish, marine shellfish, animals and
plants - however, many questions regarding the exploitation of the environment remains
underdeveloped including:
1.
2.
3.
4.
5.
6.
The duration of exploitation – seasonal or yearly?
The extent to which the environment was exploited.
How the natural resources were exploited.
Which resources were primarily exploited and their role within the economy.
Were the resources exploited locally or imported to Qwu?gwes?
Were the resources collected only for the nuclear tribal families of Eld Inlet or
was Qwu?gwes a trading hub, exporting the resources regionally?
Tentatively, there are three very distinctive areas of the Qwu?gwes archaeological site
that have each been individually investigated for the answers to these aforementioned
questions; the shellfish midden, living area, and processing area. Although each of these
areas are within close proximity of each other (approximately 10 meters), each vary
greatly in their cultural and sedimentary deposits. By examining the abundance of shell
deposition, the spatial distribution of the shells, the preservational qualities, and the
sedimentary layers exposed in the stratigraphy, it may be possible to offer suggestion to
the past environmental conditions that would have significantly influenced the habitats in
which the butter clams once occupied. Any dramatic changes seen in the cultural or
stratigraphic layers may potentially also be observed within the shell development of the
butter clam. In should be noted, the following sections of geoarchaeological analysis was
conducted by Jerred Erickson in 2001 and has primarily been referenced from his paper,
4
“Qwu?gwes Geoarchaeological Research: Stratigraphy and Seismic Influences on
Geomorphology and Habitation (45TN240).
Figure 2: Location of excavated units mentioned in the text, in relation to the layout of the site.
At the westernmost extent of the site, lies an approximate 91 meter (300 feet) long
shellfish midden (Figure 2). The midden extends 15 meters (50 feet) west from the
shoreline and has been estimated to contain at least 1,600 cubic meters of undisturbed
archaeological shellfish remains, suggested through the analysis of manual and power
auger testing conducted in 1999 and 2000 (Foster and Croes 2002, 2). As the shell
midden is primarily waterlogged from the exposure of the twice daily marine tidal
inundations, it is this area that has preserved the majority of the cultural remains
preserved at Qwu?gwes, and thus, is believed to offer a more holistic perspective of the
past society that once inhabited the area.
5
In so far, tens of thousand shellfish remains have been collected from the midden alone,
representing many of the local species to Eld Inlet including; Olympia oysters (Ostrea
lurida), Butter clams (Saxidomus giganteus), Bay mussels (Mytilus edulis), Native
littlenecks (Protothaca staminea), Horse clams (Tresus capax), Soft-shelled clams (Mya
arenaria), Bent-nosed clams (Macoma nasuta), Basket cockles (Clinocardium nuttalli),
Moon snails, whelks and barnacles (Figure 3). Additionally, the shell midden has also
allowed for the recovery of numerous discrete cultural remains, including a large cedar
bark gill net, several pieces of woven basketry, a pendent made of a possible imported
shellfish species (suggested to be either black oyster or abalone), numerous beads, a
carved harpoon shaft, twisted fiber cordage and bindings, and a plethora of shaved wood
chips. As the shellfish midden was probably the primary source of discarded ‘garbage’
produced by the past inhabitants of Qwu?gwes, many of these items are found to be
damaged upon excavation.
Relative Frequency of Primary
Shellfish Species at Qwu?gwes
Olympia
Oysters
66%
N=74,466
Bay Mussels
3%
Horse Clams
1%
Butter Clams
28%
Littlenecks
2%
Figure 3: Relative frequency of the primary shellfish species collected from the Qwu?gwes
archaeological site.
The stratigraphy of the shell midden primarily consists of layers of undifferentiated shell
layers in varying sizes from fine to whole shell fragments. Sediments within the
stratified shell layers are minimal in presence, suggesting the shell deposits were laid
6
down regularly and frequently, which consequently limited the deposition of sediments
during tidal inundation. Below the layers of shell, a 2-3cm layer of silt, clay and some
charcoal is found continuously across the entire midden, which may reflect an isolated
storm event (Erickson 2003, 2). Below this, further stratified shell continues until two
layers of vegetal mat, comprised of mostly floral and faunal remains are exposed,
truncated only by further layers of shell. It is within the vegetal layers that the majority
of the organic cultural remains described above are preserved, including the basketry,
wood chips and netting artifacts. Following the organic deposits, further shell is laid
down atop two layers of sterile lacustral sediments; the uppermost, a thin layer of siltloam forest or terrestrial soil, possibly present as a result from past local seismic activity
in the area (Erickson 2003, 2).
To the east and northeast of the shell midden, are the tentatively called; processing and
living areas, respectively (Figure 2). These areas, unlike the shell midden, have been
preserved in a dry, arid environment, as the tides rarely extend beyond the shoreline
except during extreme storms in the winter seasons. As a result of the variation in
preservational conditions, the processing area and the living area have produced a
relatively lesser quantity of cultural remains than found in the midden area; nonetheless
significant. These areas have exposed an entirely different array of cultural materials and
stratigraphy. The deposits from the living and processing areas primarily consist of
varying lenses of silty sediments, charcoal and organic remains. Perhaps most
characterizing of this area is the distinctive, relatively thin, layer of shell, fire modified
rock and faunal remains, which offers the most compelling evidence of its habitational
use in antiquity. Compounding this suggestion, is the presence of several round and
rectangular postholes found at the sterile layer of the living area; believed to be the
remains of the past structural supports to the living accommodation/shelter area(s).
Furthermore there is evidence of at least one circular fire pit that has scarred the
stratigraphy with charred sedimentary remains located within the vicinity of the
7
postholes. In contrast to the midden area, the drysite areas do not show any evidence of
seismic activity or flooding episodes (Erickson 2003, 3).
The historical past of Mud Bay is also evident from within the current landscape, but at
this time, has not been extensively explored. At low tide, several wooden timber post
remains from a pre-existing dock can be seen emerging from the mudflats. It has been
suggested this dock was once used in the transportation of fallen timbers collected from
the local forests by the lumber industry. Further south of Qwu?gwes, a historical
homestead established in 1853 is currently undergoing excavation by SPSCC and the
Squaxin Island Tribe (Croes and Foster 2003, 2). Furthermore, shellfishing for oysters
and clams in the waters of Eld Inlet has been widely explored for many years, as evident
in the historical photograph of Figure 4.
Figure 4: Mud Bay has been extensively exploited for its natural resources for thousands of years.
This picture was taken in the 1940's depicting the exploitation of the Olympia oyster from the waters
of Mud Bay (Photo courtesy of Bob and Ira Spring, as documented in
Cheney and Mumford 1986, 10)
8
The climate of the southern Puget Sound
The climate of the Puget Sound region is important to stress as the water temperatures
have been positively linked to the successful reproduction of butter clams, as will be
discussed further, below. Climatic conditions in the southern Puget Sound are generally
described as relatively cold and wet during the winter season (October through April),
with a gradual transition in the summer (May through September) to warm, dry climatic
conditions [Figure 4 (Newton et.al 1998, 15)]. In the summer months, water
temperatures in the adjacent Bud Inlet reach an average of 14.7°C (58.46°F), declining to
9.0°C (48.2°F) in the winter [based upon water temperature studies in 1996-1997 from
station BUD005 (Newton et al. 1998)]. The relatively shallow water levels of southern
Puget Sound bays compacted with the freshwater runoff from nearby underwater aquifer
spring promotes warmer water temperatures in the summer and colder water temperatures
in the winter than its local oceanic counterparts (Newton et al. 1998, 23).
9
Chapter 3. The biology and physiology of the butter clam
The ecology of the butter clam is important to discuss in some detail, as temperature,
food availability, and reproduction, among many other environmental conditions, have an
effect on the overall development of the shell (Harbo 1997; Kozloff and Price 1996;
Cheney and Mumford 1986; Ham 1982; Morris 1980; Kozloff 1973; Quayle and Bourne
1972; Rice 1971). Changes in the environment, ultimately, are the deciphering elements
to the biological changes molluscs incur throughout their lifecycle and, thus, the
environment influences the degree of shell development, dependent upon the current
conditions. Unfortunately, much of our understanding of the ecological and biological
preferences of the clam are relatively underdeveloped, when compared to other marine
species such as the oyster and littleneck; possibly as a reflection of the butter clams
current lack of commercial importance and its only regional historical importance within
Washington State and British Columbia (Goong 1999, 1; Quayle and Bourne 1972).
Figure 5: The butter clam, with bivalve terminology commonly used throughout study.
The butter clam has a thick, hearty shell with a robust hinge, appearing in varying shades
of white to gray. The shell bears several raised concentric growth lines and grooves
along the external margin that are often found consistently patterned from the anterior to
the posterior margin. Relatively large in comparison, butter clams may reach lengths of
over 100mm (Goong 1999, 2). Butter clams are found exclusively on the Pacific Coast,
10
ranging from Humboldt Bay, CA to Alaska (Morris 1980, 27; Harbo 1997), with the
densest populations focused within Washington State in the Strait of Juan de Fuca and
central Puget Sound (Cheney and Mumford 1986, 134).
Butter clams typically inhabit the intertidal zone and less frequently the subtidal zone [330 ft MLLW (Cheney and Mumford 1986, 134; Harbo 1997, 164)], where it spends most
of its 10-15 years of life primarily sedentary, with possible suggestion it may survive up
to 20 years in the Puget Sound (Harbo 1997, 164). Occasionally the animal will move
vertically, and to a much lesser extent, horizontally after initial settlement within the
sediments (Quayle and Bourne 1972, 27). Butter clams commonly prefer substrates of
mixed porous sediments of sands and gravels with broken shell (Cheney and Mumford
1986, 134; Quayle and Bourne 1972), but have also been singularly referenced to
preferring muddy sand or muddy gravel (Hunn 1993, 25). They have been found in
waters of up to 54 meters in depth (Cheney and Mumford 1986, 134)], only restricted by
the current length of the siphon through which it feeds (Quayle and Bourne 1972, 27).
Typically, as the animal ages, the siphon elongates, allowing the animal to burrow
deeper, thus, older individuals are often found at the deeper levels than are the young.
Mature clams (38mm) are often found buried at least 30cm deep (Cheney and Mumford
1986, 134, Quayle and Bourne 1972, 27).
The reproduction of butter clams has been successfully associated with the current
environmental conditions and size of growth of the individual. Increased water
temperature is suggested to be the primary instigator of sexual reproduction in butter
clams once the animal has attained adequate growth. In the Puget Sound, Butter clams
are recorded to naturally spawn in the late spring to late summer, with the most
successful reproduction occurring when the water temperature exceeds 15°C [59°F
(Cheney and Mumford 1986, 135; Quayle and Bourne 1972, 28; Bourne 1971, 1)].
Similar observations have been made in Oregon and British Columbia, where
reproduction commences during the early months of February through July, following the
11
release of spat that will have little growth until the following spring (McCrae 2003;
Quayle and Bourne 1972, 27). As the temperatures regulate the growth of the shell, the
decline in water temperatures during the winter seasons cause the growth of the shell to
slow, often completing ceasing growth until temperatures rise the following spring
(Goong 1999, 14). Sexual maturity, determinate upon the size of the shell [commonly
38mm in length (Cheney and Mumford 1986, 135)] is reached between 4-9 years in
British Columbia and reported as often early as one year in the warmer waters of the
Puget Sound [Cheney and Mumford 1986 (Table 1)]. Following maturity, the growth of
the senile clam considerably slows exponentially, resulting in only minor shell
development until death.
12
Chapter 4. Analysis of shell growth
Butter clams were chosen for analysis in this study, because of their relative excellent
preservation and large sample size [28% of the entire sampled population (see figure 3)];
combined with a moderate amount of local research available on the biological and
ecological components of the species. The following methods and techniques employed
to determine the potential for applied management strategies of the Qwu?gwes butter
clam populations, via the analysis of shell growth, are primarily modeled after a synthesis
of Claassen’s description of accurately determining shell size and demographic analysis
(1998, 107, 146-149).
The analysis of demography relies upon the assessment of the various size frequencies
within a mollusc population. As the seasonal spawning periods of an adult mollusc
population results in the addition of a juvenile population to the collective group, there
are arbitrary variations of clam size within the given population, at any given time. If the
established adult population is capable of reproduction, thus older and in principle, larger,
the newly added juvenile population would be comparatively smaller to the preestablished adult population. More simply, this implies that large (mature) and small
(juvenile) individuals are present at any given time within a natural shellfish population;
with regards to a higher abundance of either larger or smaller clams immediately before
or after reproduction, respectively. By assigning the mean or modal population size to
the various size classes, the periods of the year in which the species were harvested may
be determined (Claassen 1998, 146-149).
Unfortunately, the various class sizes of butter clams from Eld Inlet have not been
researched for this study, as the collection period necessary to establish the vast range
size classes was beyond the temporal allotments of the research. After a review of the
published literature and inquiries to various agencies concerned with modern shellfish
populations, it appears little investigation into the size classes of butter clams within a
controlled period of time has been previously established. The length measurements of
13
modern butter clams were sampled from Kiket Island, WA over a period of six months in
a study determining age at harvest (Houghton 1973, 21); however the association
between the length measurements to the month the individuals were sampled was not
referenced. Similarly, the clam populations sampled by the Washington Department of
Fish and Wildlife from numerous locations in the Puget Sound had not recorded the
associated day the measurements of modern clam populations were conducted (see
Appendix). Moreover, it may be suggested that attaining growth averages for the size
classes of butter clams may not be widely applicable, in regards to demography, as the
long lifespan of the clams (up to 20 years) may result in an impossible amount of size
classes to determine any significant results.
However, in spite of the discovery butter clam age classes are grossly undeveloped,
unpublished, or unfeasible; what can be inferred by the overall principles of the
demographic methodology is whether or not the variances in shell size (classes) are
represented within the butter clam assemblages investigated. Ultimately the application
of the growth analysis to the ancient assemblages is expected to suggest either:
(a) only certain sizes of butter clams were being selected for harvest
- resulting in the presence of few size classes, or
(b) size preference was of little concern when selecting shellfish for harvest
- resulting in the presence of a wide range of size classes.
To determine whether the size classes of the butter clams collected from Qwu?gwes were
representative of the size classes present in natural butter clam populations, length
measurements of the ancient assemblage were attained for suggestion to the overall size
frequencies, for comparison to the length frequencies of modern clam populations. It is
expected that if any given shellfish population has been harvested, or has undergone
some sort of size selective process (i.e. preditation, disease) the growth measurements
would reflect these anomalies. With this stated, the length frequencies of the modern
populations should reflect the natural size distribution of larger and smaller individuals,
14
while if the Qwu?gwes butter clam assemblages were managed it could be expected to
see fewer ranges of length class sizes.
The ancient shellfish assemblage
The sampling procedures employed to attain the ancient shellfish assemblages preserved
at Qwu?gwes, were conducted concurrently with the overall excavation of the site during
the recovery of cultural material, during the South Puget Sound Community College field
school seasons. Excavations of 1x1 meter units were uncovered in 5 cm intervals, with
each removed 5 gallon bucket of excavated material subsequently filtered through a
series of three interlocking mesh screens (½ inch, ¼ inch, to ⅛ inch diameter,
respectively) to separate the archaeological material from the debris. All whole shells and
shell fragments with an attached umbo (Figure 6) were collected and properly labeled
according to their respected unit and level. Shells removed from the wetsite units
underwent excavation and screening via hydraulically pressured water, while shells
removed from the drysite areas were dry screened and excavated with a trowel.
Once the shells were excavated, they were placed into several plastic zip-loc bags that
were labeled with the proper provenience information, and then transported to the SPSCC
archaeology lab for processing and storage. Over the years, the lab procedures regarding
the shellfish have been slightly modified to account for the developing knowledge of
conservation methods, and the effects of these changes may be reflected in the growth
analysis results. In 1999 and 2000, holes were inserted in the plastic storage bags in the
attempt to remove the remaining traces of water, as well as, the accumulating
condensation slowly released from the shells. After later inspection of these samples, this
procedure was eliminated as the air-flow was not deemed adequate for proper drying of
the packaged shells. Subsequent shellfish assemblages are to-date, left to dry for at least
a 24-hour period atop open trays before they are package into the plastic zip-loc storage
bags. In so far, this method has proved successful in properly drying the shellfish
15
assemblages, as the shells do not show the degree of physical deterioration as the
previous assemblages endured.
With the entire shellfish assemblages air dried, each individual shell with an attached
umbo was sorted according to species and counted to attain the total representation of
each species in regards to the excavated unit and level (see Figure 3). MNI (minimum
number of individuals) estimates were initially applied in the attempts to avoid the
erroneous counting of a single bivalved individual. However, this was later forfeited as
the MNI results represented exactly half of the total shell counts; suggesting there was
not any differentiated deposition of a particular shell side orientation (right or left valve)
present throughout the distribution of the site.
Figure 6: Alignment of measurements taken to determine the shell length and height of butter clams
from the modern and ancient assemblages. Demography measurements for height were taken from
A-C, while length was measured from B-D.
To determine the average growth size achieved before death of the Qwu?gwes butter
clam assemblages, length and height measurements of each butter clam shell were
calculated using a set of plastic Vernier calipers to the 1/100th of a millimeter, with
regards to a ±0.05mm degree of possible error. Length was attained by measuring
between the anterior to posterior margins, while height was inferred by the measurement
16
from the umbo to the ventral margin (Figure 6). Shells were only incorporated into the
growth analysis study if measurements of length were possible, to allow comparison to
the modern assemblage; while shell height was recorded only when feasible for possible
comparison to related shellfish data from other locations. Growth measurements were
conducted on all butter clam shells that adequately represented accumulated length,
irrespective of side orientation.
There were over 20,000 butter clams initially collected from the Qwu?gwes site;
however, after selecting only those individuals with the remaining shell intact between
the anterior to posterior margin (Figure 6), the sample was reduced to 477 individuals, or
2.4% of the total butter clam assemblage. Although the sample is small in comparison to
the total clam counts, the measured length samples are considered representative of the
collective shellfish assemblage, as at least one shell from each of the excavated levels
from every unit, was incorporated into the study (Claassen 1998, 173); except for the
uppermost levels (0-15cm) where the poorer preservational qualities (i.e. daily exposure
to tidal action, weather, compaction, and human pressures) have limited the preservation
of complete shells. Overall, the all-inclusive shell length samples attained from the site is
expected to allow for the recognition of possible irregularities and inconsistencies in shell
growth size over a spatial resolution; and perhaps more importantly, decrease the
possibility of these potential irregularities biasing the final results. Thus, it is considered
the quantity of ancient shells incorporated into the growth analysis study is relatively
unbiased and adequately representative of the total preserved shellfish population, albeit
a smaller quantitative resolution.
To determine the mean shell length and height measurements, calculations were made by
figuring the total length/height sum of the population, divisible by the total number of
individuals included in the sampled populations. This resulted in the average length of
the clams equaling 75.98mm and an average shell height of 59.06mm (Figure 7).
Recalling from chapter 3, butter clams are reported to attain an average length of 38mm
17
in 4-9 years in the northern regions of British Columbia, while 38mm is reported to be
reached in the southern Puget Sound region within one year. Correlating these figures to
the averages attained by the shell length analysis of the ancient assemblage, it may be
suggested the clams collected from Qwu?gwes were at least one year of age before
harvest, but not older than nine years of age. However, this assumption must be taken
lightly, as the growth of an individual greatly depends on the environmental conditions of
the geographical location it occupies, and thus, growth rates are expected to vary
considerably.
Size Frequencies of the Butter Clam Assemblages From
Qwu?gwes (45TN240)
shell height (mm)
100
80
60
40
20
0
0
20
40
60
80
100
120
shell length (mm)
75.98mm mean average length, 59.06mm mean average height
Figure 7: Scatter plot displaying the shell length and height measurements; highlighting the
abundance of shells ranging from 60-95mm in length.
The vertical distribution of the shells, in regards to length, was also examined to
determine if there was any variance in the vertical depositional patterning of the ancient
shells (Figure 8). If the collective stratigraphic layers of the site are thought to represent
periodic dumping episodes, with the lowermost levels being relatively older than the
uppermost levels, the shell midden may represent a ‘snapshot’ of the past environmental
conditions in which the butter clams once survived. As shell growth is intensively
dependent upon the current environmental conditions, any dramatic changes in the
18
average shell lengths in relation to the spatial parameters of the midden, may be
suggestive of palaeoenvironmental changes over time. However, upon the visual
inspection of the vertical distribution of shell lengths (Figure 8), there did not appear to
be any dramatic differences in the deposition of the shells, vertically within the
stratigraphy or in relation to the cultural areas of the site, and thus the attempt to derive
any further conclusions were ceased.
excavated depth (cm)
Overall Distribution of Butter Clam Assemblages by
Excavated Levels
0-5
5-10
10-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
50-55
55-60
60-65
65-70
70-75
75-80
80-85
85-90
0
10
20
30
40
50
60
70
80
90
100
110
120
shell length (mm)
Figure 8: Overall distribution patterning of the butter clam assemblages, in regards to
excavated depth.
The modern shellfish assemblage
As the environment is a significant aspect to the potential shell growth of the butter clam,
as in all molluscs, it is important to attain controlled growth standards of the particular
species, preferably from the same geographical location, in which to compare the overall
growth of the ancient assemblage to. Recalling from above, butter clam populations
inhabit environments with specific environmental conditions, and thus, experience
varying growth rates. A controlled local modern collection promotes the verification and
reliability of the final analytical results.
19
Controlled samples of at least 1000 individuals, collected every month over the duration
of two years, have been suggested for accurate representation of growth standards, to
avoid the inconsistencies caused by discrepancies in the local environmental conditions
from skewing the data (Claassen 1998, 154). Further, as the growth of the butter clam is
not linear, but declines exponentially with age, a large control sample should accurately
represent the overall growth attained within a population over a period of time. The
comparison between modern and ancient populations, however, greatly relies upon the
assumption that the environment and the molluscan species have not changed over time.
However, as there have been no major climatic changes occurring in this area within the
last 1,500 years (Ham 1982, 196), it may be assumed both the modern and ancient shells
have been subjected to relatively similar environmental variation.
The modern butter clam assemblages were collected by the Washington Department of
Fish and Wildlife (WDFW) between 1997 and 2002, in the attempts to obtain records of
the natural molluscan species present in the shellfish beds of the Puget Sound region.
Concurrently, further analysis was implemented by the WDFW to determine the
respective size variations of the collected species, via measuring the shell length and
weight of the population during the particular period of sampling. Sampling
methodology consisted of the shovel excavation of a series of .3048 meter2 (1 foot2)
quadrants, along a transect extending from the shoreline to the tidal zones; ensuring
samples were collected from each of the various tidal heights (high and low). All large
shellfish species were then removed for collection by hand while the remaining substrates
were screened for any smaller individuals. The collected shellfish were then
subsequently, air dried, sorted, speciated, labeled and occasionally photographed.
Three of the sampled locations in the southern Puget Sound by the WDFW were utilized
in the establishment of the controlled modern butter clam assemblages; Cutts Island (Lat:
47.3215; Long: -122.6857), Penrose Point State Park (Lat: 47.2618; Long: -122.7438)
20
and Hope Island State Park (Lat: 47.1879; Long: -122.9236), each considered within
suitable proximity (less than 60 miles away by land) to the Qwu?gwes archaeological site
in providing comparative analysis between the modern shellfish assemblages and the
ancient shellfish assemblage (Figure 9). The sampled shells from the aforementioned
Puget Sound locations collectively resulted in the acquisition of 139 individual modern
shell measurements used in the accumulated shell length analysis; 80 individuals from
Hope Island State Park, 37 from Penrose Point State Park, and Cutts Island resulted in the
attainment of 22 sampled butter clams. The results of the analysis of growth from the
modern butter clam collections will be discussed further in Chapter 6.
21
Figure 9: Location of Qwu?gwes and the modern sampled sites in the southern Puget Sound
referenced throughout this study (Image courtesy of the USGS, Terraserver-usa.com).
Measurements of the sampled live modern butter clams were calculated similarly to the
ancient butter clams collected from Qwu?gwes; between the anterior and posterior
margin to establish shell length accumulated before death (Figure 6). Mean length
averages were calculated by summing the length frequencies of each individual, divided
by the total individuals included in the study. Additionally, the individual wet weight of
the live shellfish was also determined by the WDFW, which combined with the length
measurements, recorded the current variations in size classes of butter clams for
comparison between the numerous Puget Sound beaches. However for this study, weight
22
measurements were not suitable for comparison, as the weight calculations by the
WDFW were applied to live clams.
It should be noted, as a result of the sampling methodology imposed by the WDFW, it
may be possible the modern butter clam collection is more representative of the smaller
size classes within the respected sampled beaches, as the methodology was not
specifically targeted to the isolation of butter clam assemblages, but was rather, into
researching the abundance of shellfish in general. Their methodology was, thus, aimed at
acquiring entire shellfish populations within the given location. This may have adverse
effects upon the comparison between the modern collection and the ancient, as recalling
that with age, butter clams are found to burrow deeper within the sediments, only
restricted by the length of its siphon. This promotes the mature, larger individuals the
allowance to burrow to depths of at least 30cm, where they are often discovered. As the
WDFW was only sampling to depths of 30.48cm (1 foot) deep, this may have greatly
eliminated the larger population of individuals who were buried below the 30.48 range.
23
Chapter 5. Age at harvest (growth-line analysis)
To more aptly provide support to the results of the shell growth analysis, further
investigation of the ancient butter clam assemblages were employed, via the analysis of
the external growth lines, or annuli; to establish the approximate age of the shellfish
when harvested, or more specifically, died. As the length of the clam is dependent upon
the age of the clam (Claassen 1998, 108); the assessment of the growth lines accumulated
before the death (harvest) of the shell, should support the average length measurements
determined in the growth analysis. This is expected to not only offer further suggestion
to the isolation of specific butter clams for harvest by the past inhabitant of Qwu?gwes,
but also provide insight to the approximate amount time it took for the clams to reach the
average growth. By determining an age range that infers how old the clams may have
been when they were harvested, further suggestion may be implied as to the possible
temporal management strategies applied to the butter clam populations at Qwu?gwes.
The development of growth in most mollusc shells relies upon the deposition of new
layers of calcium carbonate (CaCO3) and conchiolin, which progressively contributes to
the currently existing shell. When the shell of the animal is open to feed, the
development of new shell is added along the inner surface of the older shell. Once the
shell is closed, the calcium carbonate is dissolved by the animal’s body fluids causing
‘increments of shell’ that appear internally and, in somewhat irregular form, externally
throughout the shell in alternated banding (Claassen 1993, 56; Gordon and Carriker 1978,
519). It is these ‘ridges and grooves’ formed during the build-up and subsequent dissolve
of the shell layers that characterize the recognizable concentric growth patterning seen on
the external margin of the butter clam shell. These periods of shell growth and decline are
greatly influenced by environmental conditions, including water temperature, salinity,
sediment type, currents, spawning and availability of food (Claassen 1998, 25). When
the current conditions are favorable to the particular species, shell growth is encouraged
and if conditions are unfavorable, growth declines. Depending upon the available
24
nutrients, tidal pressures, and air and water temperatures, the maximum size of the animal
is greatly determined by its particular local environment.
For decades, investigations into the external and internal annuli of shellfish have been
examined for the biological evidence into the environmental conditions in which the
animal once lived (Milner 2001; Goong 1999; Nelson 1981; Drover 1974; Houghton
1973; House and Farrow 1968). The growth lines of shellfish assemblages have been the
primary focus of archaeologists and marine biologists in the determination of the age,
growth rates, and the palaeoenvironmental conditions the shellfish once experienced.
Acetate peels (House and Farrow 1968), amino acid dating (Kvenvolden and Blunt
1980), thin-sectioning (Hurst 2003 unpublished; Milner 2002a; Milner 2001; Ham 1982;
Clark 1980), cross-sectioning (Goong 1999), and the identification of external growth
lines (Houghton 1973), have all been employed; in the attempts to most accurately and
effectively identify the annuli for growth line analysis, each achieving varying results and
conclusions.
Age at harvest studies, via the analysis of the external growth lines, has been somewhat
controversial as the study relies heavily upon the understanding of the environmental
tolerances of the animal, the past environmental conditions, and the reader’s ability to
accurately recognize the annual growth checks – all of which dramatically increases the
difficulty in analysis and possible degree of error. Furthermore, as the growth of the shell
exponentially slows with age, the growth lines are consequentially not represented on the
external margin to the same extent, significantly decreasing the possible degree of
accuracy. As so, the analysis of external growth lines has been suggested to be adequate
only of shells with recently deposited annuli, thus only younger individuals (Goong 1999,
64). In a study on native littlenecks (Protothaca staminea) in Kiket Island, WA, it was
determined the external annuli were easily read on the clams believed to be no older than
6-7 years of age, as the growth lines of the older individuals were found to be too difficult
to distinguish (Houghton 1973, 22). This conjures several difficulties in assigning age at
25
harvest studies to archaeological assemblages, as the age of the individuals, or even the
range of the possible ages of the individuals, is often unknown beforehand.
Figure 10: The growth lines of the ancient butter clams were isolated in the attempts to further
support the growth analysis. Annulus, such as the one the arrow is pointing to, were identified and
counted to determine the shells approximate age before harvest.
As the methodology for the analysis of the annuli required different sampling parameters
than required for the measurement of shell length, the sample of butter clams included in
this study varied slightly from the individuals utilized in the shell growth analysis. Of the
20,000 butter clams collected from the excavation of Qwu?gwes, only those shells with
the remaining margin from the umbo to the ventral edge were selected (Figure 5). As
mentioned in the sampling procedures of the growth analysis, the ventral edge of the
shells was often discovered broken, and thus the sample included in the age at harvest
study was relatively small in comparison to the sample utilized in the growth analysis,
and indeed, the entire collected assemblage. Ultimately, 146 individuals were
incorporated into the analysis of the annuli, representing only 0.73% of the total counted
butter clam population.
Annuli were primarily identified utilizing the direct assistance of a magnifying glass,
with 2x enlargement capabilities. On occasion, few of the more senile shells expressed
growth lines nearest the ventral margin, that were too closely spaced together and
26
inspection using the magnifying glass was most appreciated. Determination of the
growth lines was somewhat simple to perform and the distinctions were made with
moderate confidence. A complete annulus was considered the distance between the end
of the last growth of the previous annulus to the end of the following annulus; beginning
from the umbo to the remaining amount of shell at the ventral margin. Each annulus
present on an individual shell was individually counted and regarded as representative of
one full year of growth; reflective of the repetitive development of the annulus in the
winter seasons as influenced by the poorer environmental conditions, until the following
winter check (Goong 1999, 14).
27
Chapter 6. Results
Analysis of shell growth
The length measurements attained in the shell growth analysis have provided substantial
evidence to the most common range in which butter clams were harvested at the
Qwu?gwes site. The smallest individual recovered was 16.40mm in length, while the
largest shell was recorded at 102.70mm in length, with the average mean of the total
population represented by 75.98mm. In isolation, these figures appear to infer
preferential size selection was not occurring during the harvesting of the clams in
antiquity; however, when the length measurements are examined collectively, it is
apparent the majority of the shells (87%) are between 60mm and 95mm in length, which
implies that indeed, the butter clams which had attained adequate growth were
preferentially selected for harvest by the past inhabitants of Qwu?gwes (Figure 11).
Inspection of the length measurements derived from the sampled modern assemblages,
has provided the degree to which natural butter clams beds may vary in size at any given
time. At Cutts Island the mean average length measurements were 67.16mm, with the
smallest individual measuring at 7.70mm and the largest, 121.70mm. The mean average
length of the butter clam at Penrose Point State Park was calculated at 56.99mm, with the
smallest clam measuring 8.79mm and the largest, 106.53mm. Finally, the sampled clams
from Hope Island State Park had a mean average of 83.08mm in length; the smallest
individual was 14.10mm and the largest, 109.90mm. Comparatively, these figures are
similar to those measured from the Qwu?gwes assemblage, but when the measurements
are examined in the scatter plots expressing each of the individual measurements
collectively within their respective populations, the extreme variation found in the
modern butter clam populations are evident (Figure 11).
28
Size frequency of Butter Clams at Penrose Point State Park
1997 - 2002
140
140
120
120
100
100
length (mm)
length (mm)
Size Frequency of Butter Clams at Hope Island State Park
1997 - 2002
80
60
40
80
60
40
20
20
0
0
83.08 average length (mm)
56.99 average length (mm)
n=80
Size Frequency of Butter Clams at Qwu?gwes
(45TN240)
140
140
120
120
100
100
length (mm)
length (mm)
29
Size Frequency of Butter Clams at Cutts Island
1997-2002
80
60
40
80
60
40
20
20
0
0
67.16 average length (mm)
n=37
n=22
75.98 average length (mm)
Figure 11: Frequencies of butter clam length measurements of the modern and ancient assemblages.
n=487
Standard Deviation of Shell Length
Measurements
shell length (mm)
140
120
100
80
60
40
20
0
Qw u?gw es
Cutts Island
Penrose Point
State Park
Hope Island
State Park
Figure 12: Standard deviation of shell length measurements from the modern and ancient clam
assemblages, expressing the extreme largest, smallest and average measurements.
The extent of the length size ranges presented from the modern collections represents a
much more inclusive standard size range when compared to that of the ancient collection,
prominent from within each of the sampled modern locations; Cutts Island, Penrose Point
State Park and Hope Island State Park (Figure 11). Recalling from above, 87% of the
length measurements of the butter clams from Qwu?gwes are primarily concentrated
within the range of 60-94mm. However, comparatively it is much more difficult to
distinguish a concentrated range of growth from the modern assemblages by examination
of the scatter plots, as the variations in size are more extreme; especially noted from the
assemblages of Cutts Island and Penrose Point State Park.
The natural variability of the modern assemblages essentially reflects the natural lifecycle
of the clam, caused by the mature clams producing offspring that are subsequently
introduced into pre-established populations, effectively altering the mean average growth
of the entire population from the reflection of the older, larger individuals and the
younger, smaller individuals (Figure 12). The occurrence of this cycle of reproduction
and recruitment, repeated every year to some degree, and the vast size variations
30
observed in the length measurements of the modern assemblages may reflect the recent
incoming of juveniles to the adult population. The lack of concentrated growth
measurements is what was expected to be displayed within the natural clam beds, and
ultimately provides the much needed support to display the dramatic differences between
an ancient, human-influenced shellfish midden and the natural variation in a given clam
population.
The comparison of the ancient average growth measurements from Qwu?gwes, to other
regional studies on butter clam populations, sampled from within the Northwest Coast,
may provide possible suggestion to the required amount of time required to attain the
average growth observed in the ancient assemblages (Table 1). Several publications have
documented the average attained growth of modern butter clams within a controlled
period of time, in the attempts to acquire research to determine appropriate management
strategies in various clam beds today (Goong 1999; Nelson 1981; Quayle and Bourne
1972). Although the rate of clam growth depends largely on the geographical location of
the clam populations (Quayle and Bourne 1972, 6), and thus, the growth of one location
is not necessarily applicable to another, the observation of the determined growth rates
from the listed locations, from the more northern sampled areas to the southernmost,
offers suggestion to larger clam growth the more southern the location (Table 1).
The length measurements from Kiket Island, WA, were selected as a representative
modern comparison because of its relative closeness to Qwu?gwes and large sampling
size. Sampled butter clams were also studied at other locations nearer the archaeological
site, however, as the applied sampling procedures limited the analysis of the younger
clams (Goong 1999), they were not considered representative of the overall potential
growth in a given natural population. Applying the average growth range represented by
the Qwu?gwes butter clam assemblages, of 75.98mm, to that of the growth estimates of
Kiket Island (64mm within 8 years), suggestion could be made that the overall ancient
31
Northern British Columbia Coast
Strait of Georgia
Southern British Columbia Coast
Rate of
Growth
64mm/8-9 years
64mm/5-6 years
64mm/4-5 years
Birch Bay State Park, WA
10.31mm/year
Excluded clams
age 2.5 years and
younger.
Goong, S.A. 1999.
Brant Point, Bellingham Bay, WA
64mm/avg. 13
years
Low salinity
stresses suggested
possible reason
for slower growth
and smaller shell
sizes.
Nelson, J.M. 1981.
Kiket Island, WA
64mm/8 years
Double Bluffs State Park, WA
11.52mm/year
Potlatch State Park, WA
8.86mm/year
Sampled Locations
(northernmost to southernmost)
Puget Sound, WA
38mm/year
Oregon State
38mm/3-4 years
Notes
References
Quayle and Bourne
1972; Harbo 1997.
Houghton, J.P.
1973.
Excluded clams
age 2.5 years and
younger.
Goong, S.A. 1999.
Cheney, D.P. and
Mumford, T.F.
1986.
McCrae, J. 1995.
Table 1: Reported shell lengths and the duration of shell accumulation from various locations along
the Northwest Coast.
population was at least 8 years old, as the Qwu?gwes shells are, on average, larger than
the 64mm found at the modern location. This coupled with the suggestion that the water
temperatures of Mud Bay would be much warmer than found in British Columbia, as a
result of the more southern location, more shallow waters, and protection from the
shorelines of the inlet; it may be suggested the butter clams could, potentially, grow
comparatively quicker and were, thus, aged younger than this estimate.
Ultimately, the comparison between the Qwu?gwes butter clam assemblages and the
modern assemblages from Kiket Island, only provides insight to the possibility of the
growth of the butter clams accumulating within a defined period of time, however, the
suggestions must be held lightly, as they are solely based on the comparison of growth
32
estimates and not necessarily representative of the ancient population. However, the
comparison of the Qwu?gwes growth size, when fitted into the regional growth data,
appears to be consistent and within a normal range.
33
Age at harvest results
Age at harvest studies, via the analysis of the external growth lines, are often regarded as
a somewhat controversial method (Claassen 1998, 155; Houghton 1973). Often the
external annuli have been proven to inaccurately represent the total actual years a clam
lived, when compared to the annuli presented internally. In a study on the growth lines of
two year old Mytilus edulis individuals, the external annuli suggested the shell was of 3 to
6 years of age (Lutz 1976, cited Claassen 1998, 155); resulting an error of 1-4 years
between the internal and external growth lines of Mytilus. The age a harvest studies on
the butter clam assemblages were initially regarded with the same discretion and the final
results were considered to hold lightly to the overall significance to the study. However,
when the results of the age at harvest reflected similar patterns of clam selectivity as
inferred by the growth analysis study, the age at harvest results were reconsidered as
possibly being more accurate than previously thought.
Of the 146 individual clams assessed for age at harvest, an overwhelming 71.23% of the
sample was representative of the development of 7-9 growth lines within the lifetime of
the clams. This age range was predominate throughout the entire sampled population, as
the other clams displaying more or less annuli were dramatically less prevalent than the
clams in the 7-9 range (Figure 13). The age range of clams displaying 10 annuli was also
quite prevalent within the collection, but in comparison, was not considered as
representative of the majority. As the study concluded that the ancient butter clam
collection was dominated with shells possessing 7-9 growth lines, it may be suggested the
clams were at least 7-9 years of age before harvest, as the annuli are believed to be
representative of one full year of growth.
34
amount of shells
Age at Harvest of Qwu?gwes Butter Clam
Assemblages
40
35
30
25
20
15
10
5
0
4
5
6
7
8
9
10
11
amount of growth lines
12
13
14
n= 146
Figure 13: Overall growth line frequencies from the Qwu?gwes butter clam assemblages. Shells
attaining 7-9 annuli before death represent 71.23% of the entire sampled population.
Unfortunately the results of the age at harvest study on the ancient butter clam population
could not be compared to the modern collection utilized in the shell growth size analysis,
as determination of the isolated growth lines was not included in the investigations by the
WDFW. Had the comparison been possible, it would have either validated or invalidated
the age ranges suggested by the analysis of the annuli by imposing a standard age in
relation to the amount of annuli deposited within the given period of time, in which to
compare to the ancient assemblages. However, the following synthesis of the modern
and ancient shell growth sizes, combined with the dominate age ranges suggested by the
age at harvest study, supports the analysis of age at harvest and the validation of the
results are put forward.
35
Chapter 7. Discussion
This study has offered substantial suggestion to the potential implementation of
management practices on the butter clam populations at the Qwu?gwes site, via the
analysis of achieved shell growth before harvest and growth line analysis. The shell
lengths of the sampled ancient assemblage have determined that only those individual
butter clams which had attained adequate size, between 60-95mm, were selected for
harvest by the ancient inhabitants of Qwu?gwes. Through the investigation of the external
annuli, this suggestion is reinforced with the evidence of the majority of clams preserved
within the midden, displaying similar average age ranges, from 7-9 years of age. The
lack of variation in the size and age of the ancient butter clam assemblages implies there
was a conscious effort imposed in the preferential selection of clams that had grown to at
least a particular size before they were selected for harvest.
As the Qwu?gwes assemblages do not represent the standard deviation expressed within
the growth sizes of the modern butter clam collections, it is assumed that size preference
was a major influence during shellfish harvest of the ancient clams. This, coupled with
the evidence that the majority of the ancient shells are represented by 7-9 growth lines,
supports the suggestion the site was managed, or at the least, invalidates the suggestion
the clams were ‘unsystematically’ collected. The overwhelming abundance of larger
shells in the ancient assemblage may, essentially, reflect the greater ease in finding and
collecting the larger individuals while harvesting the shellfish beds (Drover 1974, 227).
Further, it is probable the largest butter clams were selected during harvest, in the
attempts to attain the most meat yields rather than their smaller counterparts. As it is
presumably man’s nature to select the largest, most plentiful individuals, and to exert the
least amount of energy in food collecting, (as well as to impress others!), it seems
plausible the shells sampled in both, the shell growth analysis and age at harvest studies,
are representative of the overall preserved shellfish population. However, this thought
may be biased as it assumes the same thought processes of today are applicable to the
past.
36
Although it seems likely that all of the clams presented in the process of harvesting the
shellfish beds would have been retained as to not wastefully expend the energy and time
required to sort through those individuals not deemed large enough, it may also be
probable the ancient collectors had a general assumption of what area was going to be
most productive of the larger clams, by the recognition of the clam’s siphon. As the
mudflats are exposed twice daily during low tide, it seems inconceivable and quite
belittling to suggest the siphons were not noticed by the ancient harvesters. Shellfish
harvesters today often use the siphons of shellfish as indicators of specific species, and
there have been several books published on what each species’ siphon looks like when
protruding from the beach surface (e.g. Harbo 1997). Once the association of the siphon
to the particular clam was established by the past inhabitants of Qwu?gwes, it is possible
the size of the buried clams could soon be estimated by the size of the exposed siphon,
with experience.
These suggestions, however, unintentionally imply that only those clams that were within
the targeted shell size range (60-95mm) were the only clams necessarily removed from
the shellfish beds for further processing. Little suggestion is given to the possibility of the
midden not representing the total butter clam harvests, as a whole; via the results of the
applied studies. It is probable the smaller and larger butter clams were utilized for
alternative purposes, such as bowls or decoration; leading to their permanent removal
from the site or, plainly, were not deposited in the ‘garbage dump’. Further, the
preservational properties of the last 500 years may have not been suitable for the
extended existence of the smaller, more fragile individuals, in comparison to the larger,
more robust shells. This would have resulted in the average length sizes and annuli
counts from the ancient clam collection represented by only the larger shells, and not
representative of the originally harvested population. Further investigation of the
preservational qualities of the shellfish should be tested to determine the degree of
accurate representation in preserved waterlogged shellfish middens. However, as there
37
isn’t any current evidence supporting or invalidating this suggestion within the preserved
midden, the implications of the growth analysis and age at harvest are believed to
accurately infer the growth averages of the clams that were deposited within the middens
and subsequently, preserved over time.
Although the analyses conducted in this study provide insight to the size and age ranges
of the predominant available butter clams from the shellfish beds of Qwu?gwes, many
unanswered questions remain as to the specifics of the butter clam harvest. Little can be
suggested from the aforementioned measurements to the details of a possible
management regime implemented for the successful harvest of the ancient butter clams. It
remains unknown whether only the larger shells were selected for harvest, sorting them
from the smaller individuals; or if the clam beds were exploited on a rotational temporal
regime, only harvesting those beds which had been left alone to mature, increasing the
success of harvesting larger individuals once considered suitable for harvest. However,
as the excavation of the archaeological site has resulted in the acquisition of over 20,000
individual butter clams, it may be suggested the overall collection represents several
episodic harvesting seasons, rather than just one plentiful harvest. It may be possible a
variety of harvesting regimes were implemented over the duration of occupation at
Qwu?gwes. Ultimately, the grand abundance of the preserved shellfish, coupled with the
predominance of the butter clam shells within similar size and age ranges, suggests that
some variety of social or cultural code was implemented in the controlling and regulation
of the local butter clam stock.
Further, whether the shellfish beds were harvested seasonally or yearly remains to be
suggested by the results of growth analysis or age at harvest, alone. However, suggestion
from the several environmental conditions that would have greatly influenced the
abundance and productivity of butter clam harvest at Qwu?gwes, may provide further
insight to possible harvesting schedules at Mud Bay. On the southern coast of California,
winter was determined the most productive season for the harvest of the Chione clam, as
38
the other resources commonly exploited during the spring, summer, and fall, were since
deprived (Drover 1974, 230). The focused exploitation of the Chione clam in winter was
found to have resulted from the increase in the coliform bacteria that causes ‘red tides’
during the months of June through September, most notably in July and August (Drover
1974, 230). This greatly limited the available seasons in which the clam was considered
appropriate for harvest. Were similar environmental conditions present at the beaches of
Qwu?gwes, this would lead to the suggestion the butter clam was not harvested yearround, but rather were exploited when possible disease of the clam was less prone.
Similar arguments have also been forwarded regarding the seasonal harvest of oysters.
On the southeast coast of the USA, it was determined the harvest of the oyster
(Crassostrea virginica), was halted during the summer seasons when spawning greatly
reduced the available yield of nutrients, and increased the probability of containing
disease (Russo 1991, 206). If similar reproductive parameters were influential to the
seasons in which butter clams were harvested at Qwu?gwes, it could be suggested several
months of the year butter clam harvest was also avoided. The possible months this may
have occurred can be implied by the association of the current yearly water temperatures
and the temperature requirements to instigate butter clam reproduction. Recalling that
butter clams most successfully reproduce when the water temperatures exceed 15°C,
suggestion can be inferred to the lack of butter clam harvests between the months of June
through October, when water temperatures are commonly within the required range
(Figure 14). If the same regards to butter clams were applied as they were on the southern
coast to oysters, this may imply butter clams were not harvested during these months as
the nutritional properties of the clams were negatively affected by the spawning processes
of the clam. This assumption, however, relies greatly upon the similarity between human
preference along the coastlines, as well as the assumption the butter clam or the water
temperatures have not changed over time.
39
20
18
16
14
12
10
8
6
4
2
0
O
-9
N 5
-9
D 5
-9
J- 5
9
F- 6
96
M
-9
A- 6
9
M 6
-9
6
J9
J- 6
9
A- 6
96
S9
O 6
-9
N 6
-9
D 6
-9
J- 6
9
F- 7
9
M 7
-9
A- 7
9
M 7
-9
7
J9
J- 7
9
A- 7
97
S9
O 7
-9
7
temperature (degree C)
Bud0005 Water Temperature 1995-1997
months sampled
Figure 14: Ranges of water temperature recorded by the Washington State Department of Ecology in
1996 and 1997 from the adjacent Budd Inlet (Newton et al. 1998). The most successful temperature
for butter clam reproduction, 15°C, is highlighted by the red line
Several possible errors in both the shell growth analysis and the age at harvest analysis
may have contributed to overall faulty observations made throughout the study,
ultimately leading to possible incorrect results. The disadvantages of not obtaining a
modern sample from within Mud Bay may have contributed to an inappropriate
comparison between the typical growth range averages present within a given natural
population and the ancient assemblage. Further, the relatively small sample size of the
modern assemblages, coupled with the limited sampling procedures, may be
unrepresentative of the average natural population at the respected sampled locations. If
the modern population sampled from Cutts Island, Penrose State Park or Hope Island
State Park do not accurately represent the natural shell size distributions that would have
been present within the substrates of Mud Bay in antiquity, it is possible the inferred
conclusion that the concentrated size classes are atypical of natural populations, may be
invalid. This, however, suggests that the entire ancient butter clam population was the
same size at any given time, which is extremely unlikely, as it infers the clam population
did not reproduce. Nonetheless, until the growth averages of the ancient clams are
40
successfully compared with modern growth averages from clams derived from Mud Bay,
the results remain somewhat incomplete.
Further observational errors may have also occurred during the analysis and identification
of the annuli. Difficulties arose when attempting to assign the individual growth lines on
several of the clams used in the age at harvest analysis, the annuli appeared to have been
‘erased’ from the shells, which may possibly be a result of the manner in which the
ancient butter clam assemblages were processed for storage. It is also possible the
isolation of a yearly annulus was misidentified by confusing a growth line irregularly
deposited during spawning or trauma (Claassen 1998, 155). Further, the external annuli
may have not been representative of the actual amount of years it had survived, as has
been seen in previous studies (e.g. Claassen 1993).
Ultimately, it is believed the possibility of drawing faulty conclusions based on the
shortcomings of the applied studies, is significantly overcome as the results of the overall
study appear to compliment each other.
41
Chapter 8. Conclusions
The importance of shellfish to the ancient inhabitants of Qwu?gwes is evident in the vast
abundance of shellfish preserved throughout the site. However, little is known of the
manners in which these shellfish were collected for harvest in antiquity. The analysis of
the butter clam shells preserved at Qwu?gwes, via the investigation of the shell growth
attained before harvest and the analysis of the external annuli, determined the majority of
the harvested clams were within 60-95mm in length and aged from 7-9 years. This likely
suggests that direct management strategies were implemented on the butter clam beds, by
the past inhabitants of Qwu?gwes; however, the details of this regime remain unknown,
and only speculative, until further analysis and investigation can be considered.
Ultimately, the collective analyses support the suggestion that the shells were
systematically harvested at Mud Bay, attaining the largest and most plentiful collection.
Thus, this implies a likely statute within the social or cultural aspects of the past society
was involved and enforced in the regulating and standardizing of butter clam harvests, by
the ancient people of Qwu?gwes.
42
Bibliography
Bourne, N. F. 1971: The Effects of Temperature, Salinity and Food on the Development
of the Larvae of Butter Clams (Saxidomus giganteus, Deshayes) [abst.]. National
Shellfisheries Association, Proceedings 61: 1.
Buchanan, W.F. 1988: Shellfish in the Prehistoric Diet. Elands Bay, S.W. Cape Coast,
South Africa, Oxford, England. BAR International Series 455.
Cheney, D.P. and Mumford, T.F. Jr. 1986: Shellfish and Seaweed Harvests of Puget
Sound. Seattle.
Claassen, C. 1998: Shells. Cambridge.
Claassen, C. 1993: Problems and Choices in Shell Seasonality Studies and Their
Impact on Results, Archaeozoologia 5, 55-76.
Clark, G.R. 1980: The Study of Shell Structure and Growth Lines Using Thin Sections,
Skeletal Growth in Aquatic Organisms, 607-612.
Collier, S. and Hobson, K.A. 1987: The Importance of Marine Protein in the Diet of
Coastal Australian Aborigines, Current Anthropology 28, 559-564.
Croes, D. and Foster, R. 2003: Perishable Artifact from Northwest Coast Wet Sites – A
Critical Need for Native American Expertise. WARP 10th International
Conference, Wetsite Connections, April 1-5, 2003, Conference Pre-Prints.
Olympia, WA. 1-9.
Drover, C. 1974: Seasonal Exploitation of Chione Clams on the Southern California
Coast, Journal of California Anthropology 1, 224-231.
Erickson, J. 2001: Qwu?gwes Geoarchaeological Research: Stratigraphy and Seismic
Influences on Geomorphology and Habitation (45TN240), in R. Foster and D.
Croes, Qwu?gwes Archaeological Project Final Preliminary Report for 2002.
Erlandson, J.M. and Moss, M.L. 2001: Shellfish Feeders, Carrion Eaters, and the
Archaeology of Aquatic Adaptations, American Antiquity 66, 413-432.
Foster, R. and Croes, D. 2003: Qwu?gwes Archaeological Project Final Preliminary
Report for 2002. Squaxin Island Tribe/South Puget Sound Community College
Investigations, unpublished.
43
Foster, R. and Croes, D.R. 2002: Tribal – Archaeological Cooperative Agreement: A
Holistic Cultural Resource Management Approach, Journal of Wetland
Archaeology 2, 25-38.
Goong, S.A. 1999: Growth and Age Determination of Butter Clams (Saxidomus
giganteus Deshayes) on Selected Beaches in the State of Washington, with
Comments on Recruitment. MA Thesis, University of Washington, Seattle, 1-70.
Gordon, J. and Carriker, M.R. 1978: Growth Lines in a Bivalve Mollusk: Subdaily
Patterns and Dissolution of the Shell, Science 203, 519-521.
Ham, L. 1982: Seasonality, Shell Midden Layers and Coast Salish Subsistence Activities
at the Cresent Beach Site, DgRr1. Unpublished Ph.D. Dissertation, Department
of Anthropology and Sociology. University of British Columbia, Vancouver.
Harbo, R.M. 1997: Shells and Shellfish of the Pacific Northwest. Madeira Park.
Houghton, J.P. 1973: The Intertidal Ecology of Kiket Island, Washington, with
Emphasis on Age and Growth of Protothaca staminea and Saxidomus giganteus.
Ph.D. Thesis, University of Washington, Seattle, WA., 1-179.
House, M.R. and Farrow, G.E. 1968: Daily Growth Banding in the Shell of the Cockle,
Cardium edule, Nature 219, 1384-1386.
Hunn, E.S. 1993: Squaxin Island Indian Shellfish Use: A report.
Hurst, J. 2003: Determining an Applicable Method to Infer Seasonality of the Shellfish
from the Qwu?gwes site (45TN240). Unpublished assignment for the University
of Exeter, UK.
Koike, H. 1979: Seasonal Dating and the Valve-pairing Technique in Shell-midden
Analysis, Journal of Archaeological Science 6, 63-74.
Kozloff, E.N. 1973: Seashore Life of Puget Sound, the Strait of Georgia and the San
Juan Archipelago. Seattle and London.
Kozloff, E.N., and L.H. Price. 1996: Marine Invertebrates of the Pacific Northwest.
Seattle.
Kvenvolden, K.A. and Blunt, D.J. 1980: Amino Acid Dating of Saxidomus giganteus at
Willapa Bay, Washington, by Recemization of Glutamic Acid. In P.E. Hare,
T.C. Hoering and K. King, Jr. (eds.), Biogeochemistry of Amino Acids.
44
McCrae, J. 1995 Oregon Developmental Species Oregon Department of Fish and
Wildlife
(http://hmsc.oregonstate.edu/odfw/devfish/sp/bay_clam.html)
Milner, N. 2001: At the Cutting Edge: Using Thin Sectioning to Determine Season of
Death of the European Oyster, Ostrea edulis, Journal of Archaeological Science.
28, 861-873. (http://archaeology.ncl.ac.uk)
Milner, N. 2002a: Incremental Growth of the European Oyster Ostrea edulis:
Seasonality Information from Danish Kitchen Middens. BAR International
Series 1057.
Milner, N. 2002b: Oysters, Cockles and Kitchenmiddens: Changing Practices at the
Mesolithic/Neolithic Transition, in P. Miracle and N. Milner (eds.), Consuming
Passions and Patters of Consumption, 89-96.
Morris, P.A. 1980: Pacific Coast Shells. Boston.
Nelson, J.M. 1981: Age Classes, Growth and Population Density of the Butter Clam
Saxidomus giganteus Deshayes at Brant Point, Bellingham Bay, Washington,
MS. Thesis, Western Washington University.
Newton, J.A., Albertson, S.L., Nakata, K. and Clishe, C. 1998: Washington State
Marine Water Quality in 1996 and 1997. Washington State Department of
Ecology, Environmental Assessment Program, Olympia, WA. Waterbody No.
WA-01-0010, Publication 98-338.
Peacock, E. 2000: Assessing Bias in Archaeological Shell Assemblages, Journal of
Field Archaeology 27, 183-196.
Quayle, D.B. and Bourne, N. 1972: The Clam Fisheries of British Columbia. Fisheries
Research Board of Canada, Biological Station, Nanaimo, B.C., Bulletin 179.
Rice, T. 1971: Marine Shells of the Pacific Northwest. Ellison Industries, Inc.
Edmonds, WA.
Russo, M. 1991: A Method for the Measurement of Season and Duration of Oyster
Collection: Two Case Studies from the Prehistoric South-east U.S. Coast,
Journal of Archaeological Science 18, 205-221.
Wessen, G.C. 1983: Subsistence Patterns as Reflected by Invertebrate Remains
Recovered at the Ozette Site. Laboratory of Anthropology, Washington State
University, Pullman, WA.
45
Appendix
The following is a supplemental list of the length measurements recorded from the
modern and ancient butter clams utilized in this study. I have also included the weight
measurements graciously provided from the WDFW and the height measurements from
the Qwu?gwes shellfish assemblages. Collectively, the data has been attached to this
report in the attempts to hopefully assist in further biological and archaeological shellfish
studies on the Northwest Coast. Publication of raw data collections such as these are
currently rare, but with continual research and accessibility they could greatly contribute
to a ‘master list’ in which records of shell measurements may be available for research
from a multitude of beach locations statewide.
*Empty cells for shell height from the Qwu?gwes site infers the individual shell was not capable of
measurement between the umbo to the ventral margin exclusively due to the shell being severely damaged
along these distances
Unit
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
15/20
2000
70.30
15/20
2000
82.80
65.50
20-25
2000
84.40
67.00
30-35
2000
61.70
46.30
30-35
2000
70.00
30-35
2000
73.10
57.80
30-35
2000
58.80
44.70
30-35
2000
59.70
47.90
30-35
2000
68.70
30-35
2000
73.30
57.90
35-40
2000
79.10
57.00
35-40
2000
62.40
49.70
35-40
2000
79.80
57.90
35-40
2000
79.50
57.90
40-45
2000
85.20
68.70
40-45
2000
69.70
54.50
45-50
2000
25.50
18.90
45-50
2000
28.30
22.10
45-50
2000
66.10
45-50
2000
73.30
55.90
45-50
2000
86.70
45-50
2000
80.90
61.60
45-50
2000
81.20
62.70
46
Unit
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
14/16
15/16
15/16
15/16
15/16
15/16
15/16
15/16
15/16
15/16
15/16
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
45-50
2000
74.10
57.10
45-50
2000
73.00
56.20
50-55
2000
85.40
50-55
2000
71.90
55.30
50-55
2000
53.70
42.20
50-55
2000
64.10
50-55
2000
80.00
64.10
50-55
2000
78.80
61.30
50-55
2000
83.20
69.50
50-55
2000
72.30
55.50
55-60
2000
16.40
12.50
55-60
2000
16.80
12.00
55-60
2000
32.60
24.30
55-60
2000
65.10
48.30
55-60
2000
51.10
40-45
2000
90.10
71.10
70-75
2001
69.00
50.40
70-75
2001
79.90
62.50
70-75
2001
70.40
58.10
70-75
2001
90.80
67.60
70-75
2001
85.50
63.50
70-75
2001
54.90
42.40
75-80
2001
69.60
53.70
75-80
2001
75.50
57.10
75-80
2001
86.60
64.20
15-20
2000
97.60
81.00
15-20
2000
97.50
76.90
15-20
2000
81.80
63.50
20-25
2000
73.10
59.40
20-25
2000
73.40
55.80
25-30
2000
94.80
30-35
2000
64.30
53.20
30-35
2000
58.30
45.00
30-35
2000
80.50
6.90
35-40
2000
82.40
63.20
35-40
2000
68.30
52.20
35-40
2000
78.30
62.80
35-40
2000
66.70
50.60
35-40
2000
76.80
35-40
2000
62.60
35-40
2000
70.20
71.90
35-40
2000
71.00
55.50
47
Unit
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
35-40
2000
65.40
47.00
35-40
2000
74.50
57.10
35-40
2000
78.50
59.90
40-45
2000
80.50
65.50
40-45
2000
69.40
40-45
2000
69.10
45-50
2000
75.50
58.90
45-50
2000
70.20
45-50
2000
59.90
48.70
45-50
2000
73.20
50-55
2000
71.70
51.40
50-55
2000
81.90
60.90
50-55
2000
78.60
57.30
50-55
2000
79.70
61.80
50-55
2000
71.90
56.70
50-55
2000
73.90
56.50
50-55
2000
69.60
52.40
50-55
2000
75.10
57.30
50-55
2000
79.00
50-55
2000
77.80
60.40
50-55
2000
86.40
65.70
50-55
2000
67.50
50-55
2000
72.00
50-55
2000
77.20
60.20
55-60
2000
54.50
42.40
55-60
2000
77.40
57.00
55-60
2000
67.50
50.20
55-60
2000
76.50
60-65
2000
78.20
61.50
60-65
2000
37.80
30.30
60-65
2000
58.30
44.80
60-65
2000
39.90
31.30
60-65
2000
63.30
47.80
60-65
2000
76.80
62.80
60-65
2000
79.60
62.40
60-65
2000
79.30
65.30
60-65
2000
81.50
62.80
60-65
2000
95.40
79.10
60-65
2000
65.80
49.10
60-65
2000
85.30
65.80
60-65
2000
86.40
63.90
60-65
2000
81.00
61.30
48
Unit
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
15/17
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
60-65
2000
80.90
59.10
60-65
2000
96.20
75.80
60-65
2000
69.60
51.30
60-65
2000
45.80
36.40
60-65
2000
53.60
41.50
60-65
2000
77.50
60.40
65-70
2000
98.10
68.70
65-70
2000
84.00
63.90
65-70
2000
101.20
75-80
2001
59.30
46.90
75-80
2001
81.50
63.40
75-80
2001
86.50
75-80
2001
72.60
53.40
75-80
2001
90.10
69.60
75-80
2001
93.70
71.70
20-25
2000
81.40
25-30
2000
74.00
57.40
30-35
2000
25.70
19.40
30-35
2000
71.10
55.90
30-35
2000
78.20
63.90
30-35
2000
71.10
55.90
35-40
2000
71.90
59.30
35-40
2000
63.90
65.70
35-40
2000
66.00
40-45
2001
68.70
54.70
40-45
2001
88.90
67.40
40-45
2001
70.70
50-55
2001
58.10
45.50
50-55
2001
74.80
56.30
50-55
2001
69.70
50-55
2001
79.80
60.70
50-55
2001
98.10
50-55
2001
83.20
62.90
50-55
2001
100.30
80.30
50-55
2001
80.10
63.90
50-55
2001
80.80
64.90
50-55
2001
93.00
70.10
50-55
2001
90.40
71.80
50-55
2001
93.70
69.30
50-55
2001
85.50
62.90
50-55
2001
72.40
55.00
50-55
2001
89.50
67.30
49
Unit
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
16/16
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
50-55
2001
86.20
62.10
50-55
2001
81.90
65.60
50-55
2001
89.40
71.80
50-55
2001
72.90
54.80
50-55
2001
79.60
60.00
50-55
2001
78.20
60.50
55-60
2001
76.20
44.30
55-60
2001
75.30
55.00
55-60
2001
81.10
60.00
55-60
2001
89.30
66.80
55-60
2001
89.40
66.20
55-60
2001
76.40
57.80
55-60
2001
76.10
56.90
55-60
2001
89.00
66.80
55-60
2001
75.10
55-60
2001
75.70
55.40
55-60
2001
73.60
59.00
55-60
2001
77.10
55-60
2001
77.40
60.80
55-60
2001
83.00
63.80
55-60
2001
72.80
58.90
55-60
2001
86.80
65.00
60-65
2001
80.40
62.30
60-65
2001
67.60
60-65
2001
71.90
57.90
60-65
2001
87.10
67.40
60-65
2001
76.40
58.40
60-65
2001
70.00
54.30
60-65
2001
69.70
48.50
60-65
2001
71.70
53.70
60-65
2001
81.40
61.50
60-65
2001
58.20
60-65
2001
89.30
68.90
65-70
2001
89.70
69.10
65-70
2001
94.20
73.60
65-70
2001
77.90
65-70
2001
73.40
57.10
65-70
2001
80.30
61.00
65-70
2001
81.90
62.00
65-70
2001
78.60
59.60
65-70
2001
79.30
59.50
65-70
2001
82.30
63.00
50
Unit
16/16
16/16
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
70-75
2001
60.90
70-75
2001
81.40
50-55
2000
62.10
47.10
50-55
2000
98.50
76.10
55-60
2000
63.30
55-60
2000
66.40
55-60
2000
91.20
72.00
55-60
2000
79.80
55-60
2000
87.90
69.90
60-65
2000
100.20
78.30
60-65
2000
102.30
60-65
2000
86.60
67.50
60-65
2000
72.50
55.20
60-65
2000
88.40
68.40
60-65
2000
75.60
60-65
2000
87.30
68.40
65-70
2000
72.40
59.10
65-70
2000
92.80
70.30
65-70
2000
72.80
61.30
65-70
2000
89.80
73.70
65-70
2000
64.60
48.00
65-70
2000
78.60
62.60
65-70
2000
83.90
66.40
65-70
2000
86.10
67.20
65-70
2000
91.40
69.80
65-70
2000
91.50
65-70
2000
96.90
76.40
65-70
2000
80.60
60.70
65-70
2000
99.60
78.50
70-75
2000
82.80
70-75
2000
46.70
37.50
70-75
2000
81.40
67.30
70-75
2000
72.60
56.30
70-75
2000
76.60
57.20
70-75
2000
70.10
52.90
70-75
2000
78.50
62.70
70-75
2000
79.10
63.10
70-75
2000
98.20
76.30
70-75
2000
88.70
67.30
70-75
2000
86.70
62.60
70-75
2000
97.80
78.20
70-75
2000
77.10
60.20
51
Unit
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/14
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
75-80
2000
33.00
28.50
75-80
2000
59.60
37.90
75-80
2000
67.30
52.90
75-80
2000
88.40
68.70
75-80
2000
82.00
64.30
75-80
2000
90.00
71.80
75-80
2000
82.30
63.40
75-80
2000
66.10
53.40
75-80
2000
76.50
55.80
75-80
2000
92.20
75-80
2000
90.20
70.50
75-80
2000
78.70
62.90
75-80
2000
66.30
49.00
75-80
2000
72.50
75-80
2000
72.90
54.10
80-85
2000
84.70
68.80
80-85
2000
76.60
55.00
80-85
2000
81.70
60.20
80-85
2000
81.90
62.70
85-90
2000
77.30
85-90
2000
102.70
85-90
2000
69.40
55.40
85-90
2000
73.10
85-90
2000
66.50
85-90
2000
89.50
69.00
15-20
2001
86.80
65.10
15-20
2001
75.40
15-20
2001
74.90
56.70
20-25
2001
85.40
61.20
20-25
2001
93.50
20-25
2001
82.90
20-25
2001
72.10
20-25
2001
92.10
73.80
20-25
2001
87.40
25-30
2001
84.60
25-30
2001
95.00
79.30
25-30
2001
82.20
67.10
25-30
2001
77.40
56.30
25-30
2001
74.00
57.90
30-35
2001
96.40
30-35
2001
18.30
62.00
30-35
2001
76.00
54.30
52
Unit
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
30-35
2001
71.10
56.70
30-35
2001
68.40
30-35
2001
91.80
67.90
30-35
2001
87.10
72.70
30-35
2001
91.40
66.70
30-35
2001
90.00
70.70
30-35
2001
94.70
73.40
30-35
2001
80.90
63.30
30-35
2001
91.80
66.40
30-35
2001
78.20
60.00
30-35
2001
82.40
62.80
30-35
2001
88.60
70.40
30-35
2001
73.90
60.50
30-35
2001
87.50
67.30
30-35
2001
78.90
30-35
2001
71.70
30-35
2001
83.50
62.20
30-35
2001
80.30
62.60
30-35
2001
62.80
48.90
30-35
2001
78.40
63.20
30-35
2001
81.10
61.30
30-35
2001
78.10
30-35
2001
76.60
35-40
2001
79.80
35-40
2001
86.60
62.30
35-40
2001
77.10
61.20
35-40
2001
82.10
35-40
2001
75.80
57.50
35-40
2001
73.70
35-40
2001
85.70
62.60
35-40
2001
86.40
63.00
35-40
2001
80.40
35-40
2001
86.20
67.20
35-40
2001
68.20
35-40
2001
73.70
35-40
2001
90.50
72.80
35-40
2001
73.70
58.80
35-40
2001
70.70
55.00
35-40
2001
77.50
59.80
35-40
2001
77.80
58.60
35-40
2001
92.40
67.20
35-40
2001
79.70
69.70
53
Unit
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
18/15
19/14
19/14
19/14
19/14
19/14
19/14
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
35-40
2001
62.40
45-50
2001
71.80
45-50
2001
87.20
79.10
45-50
2001
64.30
84.20
45-50
2001
77.00
58.80
50-55
2001
76.50
55-60
2001
70.00
48.80
55-60
2001
59.10
45.50
55-60
2001
63.70
55-60
2001
74.10
57.80
55-60
2001
72.10
56.00
55-60
2001
82.50
55-60
2001
51.70
38.90
55-60
2001
58.90
55.80
55-60
2001
56.70
54.60
55-60
2001
70.90
54.20
55-60
2001
81.40
62.10
55-60
2001
77.00
60.40
55-60
2001
63.40
45.50
55-60
2001
66.00
52.60
55-60
2001
73.40
55-60
2001
84.10
66.50
55-60
2001
91.40
92.80
55-60
2001
71.30
55.00
55-60
2001
70.00
59.60
55-60
2001
68.40
55-60
2001
63.40
46.40
55-60
2001
83.20
65-70
2001
77.20
64.30
65-70
2001
85.90
71.90
65-70
2001
64.40
51.00
65-70
2001
70.60
58.10
65-70
2001
89.20
67.10
65-70
2001
76.10
62.20
65-70
2001
88.30
70.80
65-70
2001
66.20
10-15
2001
79.60
63.90
15-20
2001
76.50
15-20
2001
82.00
63.90
20-25
2001
84.50
63.50
20-25
2001
85.90
25-30
2001
72.00
54
Unit
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
25-30
2001
87.90
67.60
25-30
2001
89.50
67.70
25-30
2001
79.60
58.70
25-30
2001
82.50
61.40
30-35
2001
79.40
58.90
30-35
2001
68.40
53.90
30-35
2001
78.70
30-35
2001
84.30
65.20
30-35
2001
91.50
73.70
30-35
2001
82.60
30-35
2001
78.20
59.90
30-35
2001
90.50
68.70
30-35
2001
73.70
78.20
30-35
2001
70.40
53.70
30-35
2001
75.50
60.10
30-35
2001
73.30
30-35
2001
91.10
67.00
30-35
2001
78.40
66.00
30-35
2001
73.60
60.20
30-35
2001
89.80
68.90
30-35
2001
89.40
74.90
35-40
2001
71.80
35-40
2001
81.10
60.80
35-40
2001
76.40
35-40
2001
91.50
35-40
2001
76.80
58.60
35-40
2001
85.20
67.70
35-40
2001
91.80
71.10
40-45
2001
74.60
58.00
40-45
2001
73.90
57.90
40-45
2001
81.40
60.70
45-50
2001
66.30
45-50
2001
69.00
53.70
45-50
2001
78.70
63.80
45-50
2001
32.90
24.70
50-55
2001
85.50
62.70
50-55
2001
72.70
57.80
50-55
2001
52.20
42.20
50-55
2001
78.90
63.60
50-55
2001
70.40
56.90
50-55
2001
82.20
50-55
2001
97.10
79.00
55
Unit
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
19/14
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
28/26
30/26
30/26
30/26
30/26
30/26
30/26
30/26
51/25
51/25
51/25
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
50-55
2001
60.50
45.80
50-55
2001
69.50
55.00
50-55
2001
68.60
54.00
50-55
2001
78.40
61.50
50-55
2001
95.20
73.40
50-55
2001
70.90
55.00
50-55
2001
76.80
57.00
50-55
2001
71.40
53.50
55-60
2001
75.40
55-60
2001
62.60
55-60
2001
66.60
50.60
55-60
2001
58.70
45.60
10-15
2001
39.40
29.80
10-15
2001
79.00
57.20
15-20
2001
85.60
65.60
15-20
2001
81.80
63.40
20-25
2001
73.70
20-25
2001
83.40
64.80
20-25
2001
63.50
48.10
20-25
2001
75.70
59.00
20-25
2001
63.40
48.50
20-25
2001
82.80
68.10
25-30
2001
70.80
53.40
25-30
2001
76.90
56.40
25-30
2001
63.40
50.90
25-30
2001
62.50
25-30
2001
77.20
57.80
25-30
2001
70.90
56.30
30-35
2001
51.70
40.50
30-35
2001
65.90
51.00
30-35
2001
83.00
59.90
30-35
2001
59.90
46.40
0-5
2001
66.90
58.80
20-25
2001
53.70
40.90
20-25
2001
54.40
43.70
25-30
2001
64.90
48.20
25-30
2001
76.60
60.60
25-30
2001
62.80
47.10
25-30
2001
77.10
5-10
2000
99.80
78.40
10-15
2000
66.90
10-15
2000
77.20
61.60
56
Unit
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
51/25
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
52/26
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Level
Excavated
(mm)
(mm)
10-15
2000
73.00
56.00
10-15
2000
74.60
59.50
10-15
2000
76.80
60.10
10-15
2000
78.80
60.10
10-15
2000
83.90
64.30
10-15
2000
70.10
55.40
10-15
2000
73.40
54.00
10-15
2000
78.50
58.90
10-15
2000
66.30
48.00
10-15
2000
67.10
48.60
10-15
2000
73.70
55.40
10-15
2000
79.70
59.90
10-15
2000
73.60
57.40
10-15
2000
78.20
62.30
25-30
2000
91.80
72.40
25-30
2000
73.50
52.90
30-35
2000
62.10
30-35
2000
63.10
35-40
2000
73.20
54.00
45-50
2000
74.60
53.70
10-15
2000
76.50
63.70
10-15
2000
81.90
62.80
10-15
2000
70.30
10-15
2000
77.30
10-15
2000
80.30
61.80
10-15
2000
65.70
50.70
10-15
2000
76.50
10-15
2000
74.60
57.40
10-15
2000
77.10
60.20
15-20
2000
60.20
47.30
15-20
2000
76.00
59.50
15-20
2000
67.00
54.00
15-20
2000
79.10
60.80
15-20
2000
81.80
62.20
15-20
2000
78.20
60.90
15-20
2000
74.30
59.90
15-20
2000
78.50
60.30
15-20
2000
86.30
62.50
20-25
2000
74.90
58.50
20-25
2000
77.30
59.70
25-30
2000
83.90
65.20
25-30
2000
72.40
56.80
57
Qwu?gwes Archaeological Site, Olympia, WA.
(45TN240)
Year
Shell Length
Shell Height
Unit
Level
Excavated
(mm)
(mm)
52/26
40-45
2000
78.20
52/26
55-60
2000
61.00
46.20
58
Year
Sampled
1997
1997
1997
1997
1997
1997
1997
1997
1997
1997
1997
1997
1998
1998
1998
1998
1998
1998
1998
2002
2002
2002
Cutts Island
(WDFW Bidn: 280580)
Shell Length
Shell Weight (g)
(mm)
48.90
28.877
63.40
67.588
66.90
78.924
73.10
136.274
73.90
100.982
83.60
141.564
85.30
161.870
24.40
2.902
37.70
12.501
12.60
0.492
7.70
0.121
101.35
255.712
97.64
322.000
85.57
190.910
54.03
39.330
109.66
414.000
17.18
1.110
20.83
1.800
121.70
526.000
95.46
248.300
86.66
307.900
109.86
406.000
Penrose Point State Park
(WDFW Bidn: 280680)
Year
Shell Length
Shell Weight (g)
Sampled
(mm)
1997
29.80
5.428
1997
38.40
11.109
1997
46.40
24.477
1997
47.70
25.296
1997
16.70
1.103
1997
105.70
301.000
1997
18.90
1.277
1998
26.00
4.070
1998
69.05
78.870
1998
97.58
277.920
1998
94.62
219.030
1998
77.71
154.490
1998
63.04
74.220
1998
9.91
0.270
1999
59.44
36.660
1999
27.69
3.910
1999
19.98
1.580
1999
8.79
0.130
1999
8.80
0.160
1999
9.69
0.210
1999
10.29
0.210
1999
10.99
0.300
1999
90.91
305.210
1999
94.38
309.340
1999
16.91
0.950
1999
42.54
15.280
1999
36.04
9.890
1999
84.52
88.490
2002
99.61
311.900
2002
103.79
380.300
2002
106.53
431.700
2002
98.59
300.300
2002
106.28
388.000
2002
84.88
168.300
2002
80.15
186.200
2002
75.63
108.800
2002
90.85
148.300
59
Hope Island State Park
(WDFW Bidn: 280975)
Shell Length
Shell Weight
Year Sampled
(mm)
(g)
1997
14.10
0.623
1997
80.20
130.042
1997
101.40
340.000
1997
88.60
259.102
1997
25.00
3.075
1997
79.60
147.531
1997
83.20
169.190
1997
83.60
184.131
1997
86.40
184.801
1997
87.60
238.536
1997
88.70
184.161
1997
89.90
242.069
1997
96.00
317.000
1997
19.20
1.518
1997
23.00
2.324
1997
87.90
226.392
1997
94.90
267.264
1997
87.60
165.452
1997
97.10
261.665
1997
98.90
294.813
1997
90.50
261.206
1997
107.80
323.000
1997
39.00
13.088
1997
98.10
267.153
1997
89.60
252.000
1997
103.50
331.000
1997
104.60
299.000
1998
46.95
21.920
1998
97.99
263.270
1998
74.06
99.980
1998
85.63
173.760
1998
90.93
239.530
1998
91.10
249.590
1998
94.44
266.760
1998
88.18
201.800
1998
90.96
216.060
1998
91.50
233.370
1998
91.86
195.970
1998
92.13
223.780
1998
95.44
268.740
1998
107.56
343.000
1998
97.66
286.750
Hope Island State Park (continued)
Year Sampled
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
2002
60
Shell Length
(mm)
84.60
88.60
99.00
105.00
95.30
102.00
86.20
73.90
105.70
108.40
81.20
109.90
83.20
98.90
102.90
101.20
32.70
21.40
89.10
97.90
99.40
86.70
58.12
85.45
100.81
55.75
103.40
41.45
32.78
97.16
97.38
93.41
40.27
97.03
95.60
63.45
90.11
58.55
Shell Weight
(g)
207.820
218.370
277.170
336.000
272.140
311.000
167.460
110.460
323.000
358.000
136.140
386.000
168.040
237.670
308.210
289.100
5.340
2.110
256.730
280.180
259.950
202.880
44.300
281.900
328.200
44.900
383.600
16.300
8.800
285.500
264.500
297.300
15.300
298.500
242.800
78.100
241.900
49.600
61