/
!- 3r/
t
FEASIBILITY OF
OF ARTIFICIAL
ARTIFICIALCLAM
CLAl~ BEDS
BEDS
[4
C.
Dale Snow
Snow
C. Dale
Management and
Management
andResearch
Research Division
Division
Fish Commission
Commission of Oregon
Oregon
1
April
19, 1972
1972
April 19,
INTRODUCTION
For
yearsyears
the U. the
S. Army
of Engineers
or
Formany
many
U. Corps
S. Army
Corpshasofconducted
Engineers
contracted channel
channel deepening
deepening and
and maintenance
maintenance dredging
dredgingproj
projects.
ects. One
One of
the
major problems
the major
problemsofofthese
theseprojects
projectshas
hasbeen
beenthe
thedisposal
disposal of
of "spoils."
Frequently,
the easiest
easiest and
and least
least expensive
expensive disposal
Frequently,inin the
the past,
past, the
disposal sites
sites
were mud
were
mudflats
flats or
or shallow
shallowestuarine
estuarine areas
areas adjacent
adjacentto
to the
the project. This
type
disposal resulted
resulted in
in destruction
destructionof
ofclam
clam beds
beds and
and estuarine habitype of disposal
tat.
tat.
With the
development of
With
the recent development
of public
public awareness
awarenessof
of estuarine
estuarine values
and
seems desirable
desirab Ie to
to pursue
pursue
and demands
demandsforforprotection
protectionofofthese
theseareas,
areas, it
it seems
studies to
to determine
determine how
how these
can be disposed
disposed of and
and possibly
possibly
these spoils can
enhance
enhancethe
the estuarine
estuarine resources.
This
discusses two
two clam
clam beds
beds
This report discusses
that were
were inadvertently established by
by dredge
dredge spoils and
and suggests
suggests the
type
type and
and magnitude
magnitudeofofstudy
studyI Ithink
thinkisis needed
neededtoto determine
determinethe
thefeasibility
feasibility
of creating
creatingnew
new clam
clam beds
dredge spoi1s.
spoils.
beds with
with dredge
DISCUSSION
That
an established
That clam
clambeds
bedscan
canbebebuilt
builtisis an
established fact.
and
Johnson and
ofWashington,
Washington,
Gunstone,
commercial clam
Gunstone, aa commercial
clam farming
farming company
companyininthe
thestate
state of
have
clam beds
beds by
on mud
mud flats
and thus
thus
have created several clam
by placing gravel on
flats and
creating
littleneck (Venerupis
(Vene1'Upis staminea)
creating aa suitable
suitable habitat
habitat for native littleneck
clams.
clans.
In one
one instance,
instance, they
they rehabilitated
rehabilitatedaaclam
clam bed
bed in
in this
thismanner
manner
that had
had been
been destroyed
destroyed by
by flooding. The
Commission of
ofOregon
Oregon
that
The Fish
Fish Connission
has created
created aafew
few small
small experimental
experimental clam
clam beds
beds by
by using this
this method.
method.
Army Corps
known to
The
The U.
U. S.
S. Army
CorpsofofEngineers
Engineersisis known
to have
have inadvertently
inadvertently
created
leasttwo
two clam
clam beds.
beds.
created at least
A
was formed
formed in
inYaquina
Yaquina Bay
Bay
A mud
mudflat
flat was
has conduc
2.
during
during September-October
September-October1948,
1948,bybyfill
fill from
from dredging
dredgingoperationsY
operations!'
(Figure
(Figure 1). On
1950, it
itwas
was discovered
dis covered that
thatthe
thenewly
newly formed
formed
OnApril
April 7,
7, 1950,
mud flat
contained thousands
thousands of 1-year-old
l-year-old gaper
gaper clams
clams (Treaus
(TresU8 eapax,
capa:r,
mud
flat contained
also known
known asashorse,
horse, blue,
blue, blueneck,
blueneck, or
or Empire
Empire clams).
clams). Biologists
followed
set of
ofclams
clams for
forseveral
severalyears
yearstotodetermine
determinegrowth
growth and
and
followed this
this set
survival
survival rates.
rates.
By
By 1955,
1955, this
this clam
clam bed
bed contained
contained aa viable
viable population
population of
gaper clams.
clams. Population
Population estimates
this bed
bed
adult gaper
estimatesfor
forthis
this species
species in
in this
have
have been
been as
as high
high as
as 0.4 clams
clams per square
square foot
foot which
which is
is considered
considered
excellent.
Adjacent to
mud flat
the
Adjacent
to and
anddirectly
directlyrelated
related to
to the
the mud
flat is
is the
breakwater that
protects the
theNewport
Newport boat
comprised of
breakwater
that protects
boat basin. Spoils comprised
shell,
sand, and
and rock
rock were
were deposited
deposited along
along the
shell, sand,
the south
south and
and north
north sides
sides of
this breakwater
breakwater and
and at
an unknown
unknown time
setsetout
at an
timeclams
clams
outininthis
this area.
area now
contains aa good
population of gapers
now contains
good population
gapers (T.
(T.
(Sa:JJidomus giganteus,
(Saxidonius
giganteus,
This
capac),, butter
aapaz)
butter clams
clams
calledConey
Coney Island,
Island, beefsteak,
beefsteak,Washington,
Washington,
also called
giant Oregon
Oregon clam
clamororQuahog),
Quahog),and
andthe
thenative
nativeIi
littleneck
ttleneck clam
clam (V.
(V. staminea).
Until
the early
early1960's
1960' sonly
onlya alimited
limited
numberof
ofpeople
peopledug
dug clams
clams from
from
Until the
number
these beds; however,
however, as
people learned
learned of the
the beds
beds digging
digging pressure
pressure
these
as people
steadily increased.&'
increased.g;
The other
known clam
The
other known
clambed
bedaccidentally
accidentallycreated
createdby
by aa Corps
Corpsproject
project is
in Coos
Coos Bay.
Bay. This
This bed
area
bed was
wasprobably
probablycreated
createdinin 1950
1950and
andlies
lies in
in the
the area
in
near
Pigeon Point
(figUreS 2 and
and 3).
near Pigeon
Point (Figures
The
were
The area
area where
where these
these spoils were
deposited did not
not contain
containclams
clams in
inl949P11
1949EJ; and
was
deposited
andwas
wasthe
the reason
reason it
it was
selected
that time.
time.
selected as
as aa disposal
disposalsite
site at that
These'Spoiis"
createdaa small
These'Spoils" created
small
and in 1969
1969 it
was brought
brought to
attention that
thatpeople
peoplewere
were
island and
it was
to our attention
digging clams
clams there.
Investigation revealed
revealed evidence
evidence of
ofheavy
heavy digging&'
diggin~
digging
there. Investigation
Y1/
Y2/
She
l:Lfish Laboratory--Progress
Labo:rotol'Jj--P:1:'ogre8s Report
Report No.
No. 20,
20. Newport,
Newport. Oregon,
Oregon. July
JUl.y 1950.
1950.
Shellfish
Data collected
aol:Leated during
duzoing 1971
1971 and
and now
now being analyzed
anal.yzed Ulil:L
reveal. the
the number
nwnber
will reveal
of
peopl.e digging
digging on
on this
this bed
and the
the clam
al.am hcwvest
harvest by
by species.
species.
of people
bed and
£!
Notes on
on proposed
proposed channel
ahannel. dredging
dredging in
in Coos
Coos Bay,
Bay, Shellfish
Shel:Lfish Laboratory,
Labo:rotol'Jj.
3/ Notes
Special
Special. Report #12,
#12. October
Oatober 26,
26. 1949.
1949.
o
I
Xaquirra Bay
Figure
Red denotes clarn bed.
1
o
4.
I
I
(,
(,sq* ,/
I
Red denotes clam bed.
,l
l,-9
:)=
I
,ir
'.i
1l
I
l l
\,..
,'t I i
| \,
,ti
l:1
,lrl ;
l,1rir
5' ,rii
,)n nr
r--11 .
lt/i
la\([]
6.
all around
around the
the perimeter
perimeterof
of this
this island.
The
deposited conconThe materials
materials deposited
of shells,
shells,sand,
sand,and
andnibble
rubble rock
rock and
and proved
proved to
sisted of
to be
be ideal
ideal habitat
for
two of the three
three species
species that
thatbecame
became established
established there.
there. The
The clam
clam
for two
population
bed consists
consists of
ofa afew
few gaper
gaper clams
clams and
and an
an excellent
population in
in this bed
population of
littleneck and
and butter
butterclams.
clams.
population
of native
native littleneck
The
The accidental
accidental establishment
estab lishment of these
these two
two clam
clam beds
beds has caused
caused Fish
Commission
personnel
to to
speculate
onon
thethe
possibility
Commission
personnel
speculate
possibilityof
of deliberately
deliberately
clam beds.
beds. In
several of
our estuaries
there are
are areas
areas that
In several
of our
estuaries there
creating clan
never
and remain
never expose
exposeatat low
low tide
tide and
remaincovered
coveredwith
with1 1toto44feet
feet of water.
It
be carefully
carefully filled
filled with
It is
isbelieved
believed that
thatsome
some of these
these areas
areas could
could be
with
spoils so
so that
thatthey
theywould
would expose
expose at
l/2-foot minus
minus tide.
at a 1/2-foot
tide.
If
the habihabiIf the
tat
tat was
was carefully
carefullydeveloped,
developed, clams
clams could
could be
be established in one
one of
of three
ways:
(1)
(2) transplant
transplant adult
adult clams
clams into the area;
area; or
or (3)
(3)
(1) natural
natural set; (2)
plant juveniles
juveniles reared
reared in aa hatchery.!"
hatchery.1I
Fishery
in complete
Fishery biologists
biologists are not in
completeagreement
agreementononthe
thedesirability
desirability
of
such aa project.
of such
project.
From the
of of
shellfish
From
theViewpoint
viewpoint
shellfishbiologists,
biologists, this
this is
justifiableprocedure.
procedure. However,
such
However,biologists
biologists working
workingwith
withfinfish
finfish such
a justifiable
and striped bass
bass are
are convinced
convinced that these
these areas
areas are
aremore
more valuable
valuable
as shad and
as feeding
feeding grounds
grounds for
The proponents
as
for these
these species. The
proponentsofoffilling
filling feel
that
fillingto
toa aminus
minus tide level
level of
of -0.5
-0.5 to
to -1.0
-1.0foot
footcould
could create
create
that filling
additional clam
clam grounds
groWlds and
and still
still maintain
maintain feeding
feedinggrounds
groWlds for
formarine
marine
finfish.
finfish.
These
few
These feeding
feeding areas
areas would
wouldbebereduced
reducedinincapability
capability for aa few
years
years until
until eel
eelgrass
grassand
andother
otherplants
plantsbecome
become established.
STUDY PROPOSAL
PROPOSAL
STUDY
Any study
out totodeliberately
deliberatelychange
change something
something has
Any
studythat
that starts
starts out
has to
be
evaluated prior
to initiation
initiationtoto
provideadequate
adequatesafeguards
safeguards
be carefully evaluated
prior to
provide
11I
This is
is feasible
feasibZe btith
with at least
Zeast three
three species
speaies of
ofbay
bay cicvns
aZams if
if the
the
habitat is
is satisfactory.
satisfaatOZ'y.
7.
7.
destruction.
against permanent destruction
If we
are going to
to alter
alter subtidal
subtidal lands
lands
If
we are
to the
the point
point that
that they become
become intertidal
intertidal lands,
lands, we
we must
must be
be assured that
that
lands will
the newly
newly created lands
will be
be as
as valuable
valuable or more
more so
so than
than they
they were
were
as
as subtidal lands and that better
better than
than reasonable chance
chance exists
exists for
for the
success of the project.
The following
following are
are suggested requirements
requirements for
for such
such
study.
a study.
a
area selected has to have the capability of producing clams and
and
The area
should be near an area
area whore
where clams
cl3JllS occur
occur naturally.
naturally.
The study area should
be small enough that
that if
if the
the experiment
experiment is unsuccessful major
major loss
loss of
of sub-
lands will not
not have
have occurred.
occurred.
tidal estuarine lands
The clam
clam producing
producing capability
capability
The
of the bay and
and species that
that will
will grow
grow there
there must
must be
be considered.
considered.
It would
would
mandatory to
to determine
determine the
the annual
annual salinity
salinity pattern and
and what species
be mandatory
were already
already present.
present.
Soil types should be determined where clams already
spoils origin should be
occur and samples from the spoils
be analyzed to determine
their suitability for clam
clam habitat.
Studies should also be initiated to
determine if
if eel
eel grass
grass (Zosterci
(ZOstel'a sp.)
and the
the feasifeasidetermine
sp.) can
can be
be transplanted and
bili ty of
of "brush"
''brush'' fences
fences investigated
investigated as
as larvae
larvae traps.
traps.
bility
Mathematical
Mathematical
models should be developed to determine the overall effect of the fill
models
on flushing
flushing and
and salinity
salinity patterns.
patterns.
on
SCUBA divers should be employed to
determine what plants and animals exist in the area proposed for filling
prior to the actual work.
A
conA study of this nature should cover a span of about 10 years conof: 2 years of
of predredging study,
sisting of:
study, 1 year of study on the stabilization of the
zation
the fill
fill in the year that
that dredging occurs,
occurs, and the
the following
7 years
and follow
follow the
the establishnent
establishment of
ofplant
animal
years to establish and
plant and animal
in the newly created
created habitat.
habitat.
conununities
communities in
The estimated cost
cost of
of such
such
a project
project would
would be about $50,000 per year.
Two tall-time
full-time biologists
8.
8.
would be required
required to
to conduct the study, aa boat and
and motor and an allall·
terrain vehicle
Vehicle would
would nave
have to be
be purchased,
purchased, and considerable
considerable supplies
supplies
provided
to do
do the
the job.
job.
provided to
Distribution
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