Document ID: EPA-HQ-OW-2002-0049-0148
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2003-03-19T05:00Z

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(
DRAFT)
­
Taxonomy
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
TAXONOMY
NAME
­
crab,
dungeness
OTHER
COMMON
NAMES
­
Pacific
edible
crab,
edible
crab,
market
crab
and
commercial
crab
ELEMENT
CODE
­

CATEGORY
­
Aquatic
Crustaceans
PHYLUM
AND
SUBPHYLUM
­
Arthropoda,
Crustacea
CLASS
AND
SUBCLASS
­
Malacostraca,
Eumalacostraca
ORDER
AND
SUBORDER
­
Decapoda,
Dendrobranchiata
FAMILY
AND
SUBFAMILY
­
Cancridae,

GENUS
AND
SUBGENUS
­
Cancer,

SPECIES
AND
SSP
­
magister,

SCIENTIFIC
NAME
­
Cancer
magister
AUTHORITY
­
Dana,
1852
TAXONOMY
REFERENCES
­
197,
86,
260
and
231
COMMENTS
ON
TAXONOMY
­
Other
common
names
include
Pacific
edible
crab,
edible
crab,
market
crab,
commercial
crab
*
86*.

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Taxonomy
­
1
(
DRAFT)
­
Status
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
STATUS
Coded
Status
Commercial/
consumption
Sport
Fish
See
Comments
REFERENCES
FOR
STATUS
­
11323,
86
and
260
COMMENTS
ON
STATUS
­
The
Dungeness
crab
supports
a
valuable
commercial
and
sport
fishery
along
the
west
coast
of
the
US.
It
occupies
ecological
niches
in
both
marine
and
estuarine
waters
and
is
important
as
both
predator
and
prey
at
all
life
stages.
Recent
studies
on
the
environmental
consequences
of
dredging
in
estuaries
have
established
a
strong
probability
that
the
Dungeness
crab
population
is
likely
to
be
seriously
reduced
by
habitat
alteration
from
dredging
unless
proper
precautions
are
taken
to
reduce
losses
*
11323.
The
loss
of
vital
estuarine
habitat
could
significantly
reduce
recruitment
to
the
offshore
fishery
*
86*.
An
important
predator
(
on
crangon
shrimp
and
bivalves)
and
prey
(
includes
all
age
classes)
in
nearshore
and
estuarine
habitats.
Estuaries
are
important
in
early
life
stages.*
255*

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Status
­
1
(
DRAFT)
­
Distribution
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
DISTRIBUTION
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Distribution
­
1
HABITAT
ASSOCIATIONS
NATIONAL
WETLAND
INVENTORY
CODES
NWI
NWICLS
NWIMOD
NWISPEC
Marine,
intertidal
FL2
L
5
Marine,
intertidal
FL2
L
5
Marine,
intertidal
FL2
L
5
Estuarine
AB2
L
5
Marine,
intertidal
FL3
L
5
Estuarine
AB.
Marine,
subtidal
UB2
L
Marine,
subtidal
UB3
L
REFERENCES
FOR
NWI
­
86
COMMENTS
ON
HABITAT
ASSOCIATIONS
­
Eggs
occur
on
pleopods
of
female
crabs
in
euhaline
(
30­
40
ppt)
waters.
Females
with
eggs
can
be
found
intertidally
and
out
to
deeper
nearshore
waters.
Larvae
initially
occur
in
nearshore
euhaline
waters
(
5­
16
kn
from
shore),
with
offshore
movement
and
distribution
influenced
by
depth,
latitude,
temperature,
salinity,
and
currents.
Larvae
are
found
near
the
surface
at
night
and
15­
25
meters
deep
during
daylight.
Megalopae
are
in
the
upper
15
meters
both
day
and
night,
but
they
also
have
diel
migrations
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and
are
found
primarily
in
shallow
water
nearshore
areas.
Juveniles
occur
primarily
in
shallow
coastal
waters
and
estuaries.
Adults
are
found
primarily
intertidally
to
90
meters
in
marine
(
euhaline)
waters,
but
sizable
numbers
occur
in
the
lower
reaches
of
estuaries.*
255*

Habitat
Associations
­
1
(
DRAFT)
­
Food
Habits
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
FOOD
HABITS
TROPHIC
LEVEL
­
CARNIVORE
REFERENCES
FOR
TROPHIC
LEVEL
­
86
and
260
LIFESTAGE
FOOD
FOOD
PART
Larva
Zooplankton
Not
Applicable
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Juvenile
Crustaceans
Not
Specified
Juvenile
Molluscs
Not
Specified
Juvenile
Fish
Not
Specified
Adult
Malacostraca
Not
Specified
Adult
Fish
Not
Specified
Adult
Molluscs
Not
Specified
REFERENCES
FOR
ADULT
FOOD
­
86
and
260
REFERENCES
FOR
JUVENILE
FOOD
­
86
and
260
REFERENCES
FOR
LARVAE
FOOD
­
86
and
260
COMMENTS
ON
FOOD
­
Larvae
eat
both
zooplankton
and
phytoplankton,
but
zooplankton
is
most
important.
The
larvae
capture
food
items
with
the
natatory
hairs
of
their
maxillipeds,
and
size
of
food
is
a
selection
factor.
The
diet
of
juvenile
crabs
consists
largely
of
fish,
mollusks,
and
crustaceans.
Crabs
progress
from
eating
bivalves
their
first
year,
to
eating
shrimp
(
Crangon
spp.)
their
second
year,
and
finally
to
eating
juvenile
teleost
fish
in
their
third
year.
Cannibalism
is
common
among
adults
*
86*.

Food
Habits
­
1
(
DRAFT)
­
Environment
Associations
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
ENVIRONMENTAL
ASSOCIATIONS
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G
=
General
A
=
Adult
LIM
=
Limiting
RA
=
Resting
Adult
J
=
Juvenile
FA
=
Feeding
Adult
RJ
=
Resting
Juvenile
BA
=
Breeding
Adult
FJ
=
Feeding
Juvenile
P
=
Pupae
L
=
Larvae
E
=
Egg
RL
=
Resting
Larvae
FL
=
Feeding
Larvae
LIFESTAGE
ENVIRONMENTAL
ASSOCIATIONS
G
Water
Temperature:
Specified
in
Comments
G
Turbidity:
Specified
in
Comments
G
Nutrient
[
Phosphorus
and
Nitrogen]:
Specified
in
comments
G
Substrate:
Specified
in
Comments
G
Relation
to
Substrate:
Unattached
­
normally
free
living
G
Estuarine
habitat
zone:
offshore
J
Water
Temperature:
Between
21­
27
degrees
C
J
Water
Temperature:
Between
15­
21
degrees
C
J
Water
Temperature:
Specified
in
Comments
A
Water
Temperature:
Between
15­
21
degrees
C
A
Water
Temperature:
Below
15
degrees
C
A
Water
Temperature:
Specified
in
Comments
BA
Water
Temperature:
Below
15
degrees
C
BA
Water
Temperature:
Specified
in
Comments
L
Water
Temperature:
Below
15
degrees
C
L
Water
Temperature:
Specified
in
Comments
E
E
E
E
L
L
G
Bottom
Type
[
Aquatic]:
Sand
REFERENCES
FOR
ENVIRONMENTAL
ASSOC_
­
86
and
260
REFERENCES
FOR
LIMITING
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
ADULT
ENVIRONMENTAL
ASSOC_
­
260
REFERENCES
FOR
FEEDING
ADULT
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
RESTING
ADULT
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
BREEDING
ADULT
ENVIRONMENTAL
ASSOC_
­
86
and
260
REFERENCES
FOR
JUVENILE
ENVIRONMENTAL
ASSOC_
­
260
REFERENCES
FOR
FEEDING
JUVENILE
ENVIRONMENTAL
ASSOC_
­
86
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Environment
Associations
­
1
(
DRAFT)
­
Environment
Associations
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
REFERENCES
FOR
RESTING
JUVENILE
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
LARVAE
ENVIRONMENTAL
ASSOC_
­
260
REFERENCES
FOR
FEEDING
LARVAE
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
RESTING
LARVAE
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
PUPAE
ENVIRONMENTAL
ASSOC_
­
86
REFERENCES
FOR
EGG
ENVIRONMENTAL
ASSOC_
­
86
COMMENTS
ON
ENVIRONMENTAL
ASSOCIATIONS
­
The
temperature
preferences
of
adult
crabs
are
different
among
seasons.
They
are
somewhat
tolerant
of
abrupt
temperature
and
salinity
fluctuations,
and
water
temperatures
from
3
to
19
degrees
C
were
listed
as
normal
for
the
Dungeness
crab.
Dungeness
crabs
have
different
optimal
water
temperatures
at
different
stages.
In
the
laboratory,
it
has
been
reported
that
optimal
water
temperatures
for
mating
ranged
from
12
to
16
degrees
C
during
long
photoperiods.
An
apparent
trend
toward
crabs
mating
later
in
colder
water
was
noted
in
the
laboratory.
In
Washington
coastal
waters,
where
Dungeness
crabs
usually
mate
in
early
spring,
the
bottom
temperatures
are
between
8
and
10
degrees
C.
The
egg
brooding
periods
varied
inversely
with
seawater
temperatures
of
9
to
17
degrees
C.
Prolonged
egg
brooding
periods
in
colder
water
are
consistant
with
prolonged
occurrences
of
ovigerous
crabs
and
cooler
ocean
temperatures
with
progressively
northward
movement
along
the
Pacific
coast.
Hatching
success,
considered
as
the
number
of
larvae
that
hatch
from
an
egg
mass,
decreased
as
the
temperature
increased
from
10
to
17
degrees
C.
A
similar
correlation
was
found
between
egg
mortality
and
temperature
with
20%
mortality
at
10
degrees
C
and
100%
mortality
at
20
degrees
C.
Optimal
temperatures
for
larvae
are
10
to
14
degrees
C.
Juvenile
crabs,
80
mm
wide
and
acclimated
to
10
degrees
C,
have
been
exposed
to
water
temperatures
up
to
25
degrees
C
for
7
days
with
little
or
no
mortality;
however,
an
increase
of
2.5
degrees
C
above
25
degrees
C
was
fatal
to
all
crabs
tested.
In
the
laboratory,
adult
crabs
had
a
maximum
tolerable
temperature
of
25
degrees
C
during
long
photoperiods,
which
decreased
to
20
degrees
C
when
exposed
to
short
photoperiods.
With
adults
crabs
held
for
8
months,
mortality
increased
with
temperature
from
17%
at
10
degrees
C
to
58%
at
13
degrees
C
and
to
80%
at
17
degrees
C,
although
laboratory
stress
probably
exacerbated
the
effect
of
high
temperatures.
Tolerance
to
salinity
varies
among
the
life
stages
of
the
Dungeness
crab.
In
general,
salinity
is
not
as
important
as
temperature
to
egg
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development
and
hatching,
but
the
larvae
are
highly
sensitive
to
changes
in
salinity.
The
percentage
of
eggs
hatching
was
optimal
at
15
ppt,
but
hatching
occurred
to
some
degree
over
a
wide
range
of
salinities
between
10
ppt
and
32
ppt.
When
salinity
was
increased
from
15
ppt
to
32
ppt,
the
average
prezoeal
period
was
reduced
from
about
60
min
to
less
than
11
min.
At
a
salinity
of
10
ppt,
no
prezoeae
molted
to
zoeaea,
but
100%
molted
at
30
ppt.
The
highest
survival
for
larvae
was
between
salinities
from
25
ppt
to
30
ppt.
Survival
decreased
with
salinity
and
was
poorest
at
salinities
of
15
ppt.
No
juvenile
or
adult
tolerance
levels
are
available
in
the
Environment
Associations
­
2
(
DRAFT)
­
Environment
Associations
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
literature
at
this
time.
Salinity
and
temperature
are
both
related
to
larval
survival.
Significant
interaction
exists
between
these
two
factors
with
salinity
buffering
temperature.
At
favorable
temperatures,
unfavorable
salinities
resulted
in
complete
mortality,
but
favorable
salinities
at
unfavorable
temperatures
allowed
some
survival.
Adult
crabs
are
found
living
over
several
substrate
types,
but
they
prefer
sandy­
mud
bottoms.
This
preference
may
stem
from
an
abundance
of
food
organisms
on
such
substrates
or
perhaps
the
crabs
find
shelter
from
predation
there.
Older
crabs
seem
less
dependent
on
epibenthic
cover
and
can
be
found
over
more
exposed
substrates.
Most
crabs
remain
in
the
subtidal
environment,
but
may
venture
into
littoral
areas
at
high
tide.
This
behavior
is
enhanced
by
the
presence
of
preferred
food
items
and
decreased
during
low
salinities
following
heavy
rains.

COMMENTS
ON
RESTING
ADULT
ENVIRONMENTAL
ASSOC_
­
Dungeness
crabs
have
different
optimal
water
temperatures
at
different
stages.
In
the
laboratory,
it
has
been
reported
that
optimal
water
temperatures
for
mating
ranged
from
12
to
16
degrees
C
during
long
photoperiods.
An
apparent
trend
toward
crabs
mating
later
in
colder
water
was
noted
in
the
laboratory.
In
Washington
coastal
waters,
where
Dungeness
crabs
usually
mate
in
early
spring,
the
bottom
temperatures
are
between
8
and
10
degrees
C.
The
egg
brooding
periods
varied
inversely
with
seawater
temperatures
of
9
to
17
degrees
C.
Prolonged
egg
brooding
periods
in
colder
water
are
consistant
with
prolonged
occurrences
of
ovigerous
crabs
and
cooler
ocean
temperatures
as
you
move
progressively
northward
along
the
Pacific
coast.

COMMENTS
ON
FEEDING
ADULT
ENVIRONTAL
ASSOC_
­
Adult
crabs
are
found
living
over
several
substrate
types,
but
they
prefer
sandy­
mud
bottoms.
This
preference
may
stem
from
an
abundance
of
food
organisms
on
such
substrates
or
perhaps
the
crabs
find
shelter
from
predation
there.
Older
crabs
seem
less
dependent
on
epibenthic
cover
and
can
be
found
over
more
exposed
substrates.
Most
crabs
remain
in
the
subtidal
environment,
but
may
venture
into
littoral
areas
at
high
tide.

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This
behavior
is
enhanced
by
the
presence
of
preferred
food
items
and
decreased
during
low
salinities
following
heavy
rains.

Environment
Associations
­
3
(
DRAFT)
­
Environment
Associations
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
COMMENTS
ON
BREEDING
ADULT
ENVIRONMENTAL
ASSOC_
­
Dungeness
crabs
have
different
optimal
water
temperatures
at
different
stages.
In
the
laboratory,
it
has
been
reported
that
optimal
water
temperatures
for
mating
ranged
from
12
to
16
degrees
C
during
long
photoperiods.
An
apparent
trend
toward
crabs
mating
later
in
colder
water
was
noted
in
the
laboratory.
In
Washington
coastal
waters,
where
Dungeness
crabs
usually
mate
in
early
spring,
the
bottom
temperatures
are
between
8
and
10
degrees
C.
The
egg
brooding
periods
varied
inversely
with
seawater
temperatures
of
9
to
17
degrees
C.
Prolonged
egg
brooding
periods
in
colder
water
are
consistant
with
prolonged
occurrences
of
ovigerous
crabs
and
cooler
ocean
temperatures
as
you
move
progressively
northward
along
the
Pacific
coast.
Hatching
success,
considered
as
the
number
of
larvae
that
hatch
from
an
egg
mass,
decreased
as
the
temperature
increased
from
10
to
17
degrees
C.
A
similar
correlation
was
found
between
egg
mortality
and
temperature
with
20%
mortality
at
10
degrees
C
and
100%
mortality
at
20
degrees
C.

COMMENTS
ON
RESTING
JUVENILE
ENVIRONMENTAL
ASSOC_
­
Juvenile
crabs,
80
mm
wide
and
acclimated
to
10.0
degrees
C,
have
been
exposed
to
water
temperatures
up
to
25.0
degrees
C
for
7
days
with
little
or
no
mortality;
however,
an
increase
of
2.5
degrees
C
above
25
degrees
C
was
fatal
to
all
crabs
tested.

COMMENTS
ON
FEEDING
JUVENILE
ENVIRONMENTAL
ASSOC_
­
Juvenile
crabs,
80
mm
wide
and
acclimated
to
10.0
degrees
C,
have
been
exposed
to
water
temperatures
up
to
25.0
degrees
C
for
7
days
with
little
or
no
mortality;
however,
an
increase
of
2.5
degrees
C
above
25
degrees
C
was
fatal
to
all
crabs
tested.

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COMMENTS
ON
RESTING
LARVAE
ENVIRONMENTAL
ASSOC_
­
Optimal
temperatures
for
larvae
are
10
to
14
degrees
C.

COMMENTS
ON
FEEDING
LARVAE
ENVIRONMENTAL
ASSOC_
­
Dungeness
crabs
have
different
optimal
water
temperatures
at
different
stages.
In
the
laboratory,
it
has
been
reported
that
optimal
water
temperatures
for
mating
ranged
from
12
to
16
degrees
C
during
long
photoperiods.
An
apparent
trend
toward
crabs
mating
later
in
colder
water
was
noted
in
the
laboratory.
In
Washington
coastal
waters,
where
Dungeness
crabs
usually
mate
in
early
spring,
the
bottom
temperatures
are
between
8
and
10
degrees
C.
The
egg
brooding
periods
varied
inversely
with
seawater
temperatures
of
9
to
17
degrees
C.
Prolonged
egg
brooding
periods
in
colder
water
are
consistant
with
prolonged
occurrences
of
ovigerous
crabs
and
cooler
ocean
temperatures
as
you
move
progressively
northward
along
the
COMMENTS
ON
EGG
ENVIRONMENTAL
ASSOC_
­
Dungeness
crabs
have
different
optimal
water
temperatures
at
different
stages.
In
the
laboratory,
it
has
been
reported
that
optimal
water
temperatures
for
mating
ranged
from
12
to
16
degrees
C
during
long
photoperiods.
An
apparent
trend
toward
crabs
mating
later
in
colder
water
was
noted
in
the
laboratory.
In
Washington
coastal
waters,
where
Dungeness
crabs
usually
mate
in
early
spring,
the
bottom
temperatures
are
between
8
and
10
degrees
C.
The
egg
brooding
periods
varied
inversely
with
seawater
temperatures
of
9
to
17
degrees
C.
Prolonged
egg
brooding
periods
in
Environment
Associations
­
4
(
DRAFT)
­
Environment
Associations
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
colder
water
are
consistant
with
prolonged
occurrences
of
ovigerous
crabs
and
cooler
ocean
temperatures
as
you
move
progressively
northward
along
the
Hatching
success,
considered
as
the
number
of
larvae
that
hatch
from
an
egg
mass,
decreased
as
the
temperature
increased
from
10
to
17
degrees
C.
A
similar
correlation
was
found
between
egg
mortality
and
temperature
with
20%
mortality
at
10
degrees
C
and
100%
mortality
at
20
degrees
C.

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Environment
Associations
­
5
(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
LIFE
HISTORY
Morphology
and
Identification
Aids
Color:
Beige
to
light
brown
with
blue
trim
and
hue,
darkest
anteriorly,
often
light
orange
below,
sometimes
light
gray­
purple
below;
inner
sides
of
anterior
feet
and
claws
crimson,
tips
not
dark.
Short
eyestalks
with
small
orbits.
Frontal
area:
narrow
with
five
unequal
teeth,
not
markedly
produced
beyond
the
outer
orbital
angles;
middle
tooth
largest,
more
advanced
than
outer
pair;
outer
pair
form
inner
angles
of
orbit.
Teeth:
(
antero­
lateral)
ten,
counting
orbital
tooth;
widest
at
10th
tooth,
which
is
large
and
projecting;
all
teeth
pointed,
with
anterior
separations.
Postero­
lateral
margins:
unbroken,
entire,
without
teeth,
meets
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antero­
lateral
margin
with
distinct
angle.
Abdomen:
narrow
in
male,
broad
in
female.
Juveniles:
antero­
lateral
and
postero­
lateral
margins
meet
at
a
distinct
angle;
carapace
widest
at
10th
tooth;
posterio­
lateral
margin
entire;
carpus
of
cheliped
with
single
spine
above,
fingers
light
colored,
carapace
not
as
broad
as
the
adult.

Mating
Dungeness
crabs
mate
from
April
to
September
in
British
Columbia,
mostly
in
March
and
April,
but
sometimes
in
May
and
June
in
Washington,
and
March
to
July
in
California.
Mating
usually
occurs
in
offshore
locations.
Premolt
females
are
located
by
adult
males
for
mating,
possibly
through
a
pheromonal
homing
system
similar
to
those
used
by
other
crab
species.
The
female
is
held
by
the
male
in
a
premating
embrace
up
to
7
days
prior
to
her
molting.
Approximately
1h
after
molting
of
the
female
is
completed,
mating
between
the
hardshell
male
and
softshell
female
occurs.
Mating
involves
the
insertion
of
the
male
gonopods
into
the
spermathecae
of
the
female
and
the
deposition
of
spermatophores.
Following
copulation,
the
female
may
be
embraced
again
by
the
male
for
a
period
of
up
to
2
days.
Both
pre­
and
postmating
embraces
may
serve
to
protect
the
female
from
predation,
while
insuring
the
maing
success
of
the
male
by
guarding
the
female
against
other
males.
The
spermatorphores
deposited
by
the
male
in
the
spermathecae
contain
sperm
that
are
viable
for
many
months
and
which
remain
viable
through
molting
until
a
second
egg
extrusion.
Eggs
are
not
fertilized
until
extrusion,
at
which
time
they
are
attached
to
the
female
pleopod
setae
and
are
carried
beneath
the
abdominal
flap.
Eggs
hatch
in
60
to
120
days.*
86*

Eggs
and
Fecundity
Eggs
are
extruded
from
September
to
February
in
British
Columbia,
October
to
December
in
Washington,
October
to
March
in
Oregon,
and
September
to
November
in
California.
An
egg
mass
may
contain
from
one
to
two
million
eggs
and
a
female
may
produce
up
to
five
million
eggs
in
three
or
four
broods
during
her
lifetime.
Eggs
are
pale
white
to
orange
at
extrusion,
becoming
progressively
darker
in
color
as
they
develop.
Water
temperatures
and
changes
in
water
temperatures
have
considerable
influence
on
the
rate
of
egg
development
and
mortality
after
fertilization
and
spawning.
When
temperatures
rise,
the
rate
of
egg
development
also
rises,
but
so
does
the
rate
of
mortality.
Eggs
mature
in
about
2­
3
weeks.
The
hatching
season
commonly
shortens
from
north
to
south
along
the
Pacific
coast.
Eggs
hatch
in
coastal
waters
from
December
to
June
in
Life
History
­
1
(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
British
Columbia,
January
to
April
in
Washington,
December
to
April
in
Oregon,
January
to
early
March
in
northern
California
and
late
December
to
early
February
in
central
California.

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Larvae
Larvae
emerge
as
prezoeae
and
molt
to
zoeae
within
1h.
The
duration
of
the
prezoeal
period
and
the
transformation
to
zoeae
vary
with
salinity.
The
larvae
progress
through
five
zoeal
stages
before
molting
into
megalopae.
Zoeae
first
appear
within
a
distance
of
5­
16
km
from
shore.
Offshore
movement
and
distribution
of
larvae
probably
is
regulated
by
a
variety
of
factors
including
depth,
latitude,
temperature,
salinity,
and
ocean
currents.
Distribution
is
dependent
upon
the
larval
stage
and
the
larvae
shore
a
diel
pattern
of
vertical
distribution;
they
are
near
the
surface
at
night.
There
is
considerable
offshore
movement
of
larvae
that
occurs
during
the
zoeal
stages;
the
larvae
appear
to
be
transported
seaward
from
the
onset
of
hatching.
The
trend
of
abundance
of
megalops
proceeds
from
south
to
north.
Megalope
are
often
abundant
on
the
hydrozoan
Velella
velella,
when
they
are
scarce
or
absent
elsewhere
in
the
water
column.
It
is
thought
the
Velella
act
as
a
transport
mechanism
or
possibly
a
food
source
or
protection
from
predation.

Juveniles
Most
megalope
molt
into
juveniles
in
August
off
the
coast
of
British
Columbia
and
in
April­
May
off
the
coasts
of
both
Oregon
and
Washington.
After
molting,
the
juveniles
are
found
in
shallow
coastal
waters
and
estuaries,
and
large
numbers
live
among
eelgrass
or
other
aquatic
vegetation
that
provides
protection
and
substrate,
and
harbors
food
organisms
for
early
instars.
Recently,
shells
of
bivalves
such
as
Mya
arenaria
and
Crassostrea
gigas
have
been
documented
as
very
important
habitat
for
young
crabs.
In
cental
California,
there
is
evidence
that
movement
of
postlarval
Dungeness
crabs
into
the
estuaries
takes
place
in
May
and
June
via
bottom
currents,
where
they
stay
for
11­
15
months.
Juveniles
are
common
in
estuaries,
while
subadults
and
adults
are
common
offshore.
Juveniles
most
11
or
12
times
prior
to
sexual
maturity.
Carpace
width
at
the
first
instar
varies
from
about
5
mm
to
greater
than
8.5
mm.
After
1
year
of
growth
beyond
hatching,
most
crabs
(
in
California)
are
in
their
8th,
9th,
or
10th
instar.
By
comparison,
crabs
in
Washington
attain
only
the
sixth
or
seventh
instar
by
the
end
of
their
first
year
of
life.
Crabs
mature
after
about
2
years
at
carpace
widths
of
about
116
mm
for
males
and
100
mm
for
females.

Adults
At
about
4
years
old,
most
adult
Dungeness
males
in
the
coastal
waters
of
Washington
are
of
marketable
size
(>
159
mm).
Marketable
crabs
usually
only
most
once
a
year.
The
maximum
lifespan
of
Dungeness
crabs
is
8
to
10
years.
The
maximum
size
attained
is
about
218
mm
CW
in
males
and
160
mm
CW
in
females
at
the
16th
instar.
Along
the
coast
of
northern
California,
legal­
sized
male
crabs
probably
move
offshore
(
often
to
the
south
or
north)
in
late
summer,
sometimes
through
early
winter;
sometime
in
winter
the
direction
of
movement
is
probably
reversed
and
the
crabs
return
inshore.
Crabs
display
a
definite
diel
activity;
they
are
more
abundant
by
day
in
the
subtidal
area
and
more
abundant
at
night
in
the
intertidal
area;
the
response
is
positively
correlated
with
food
availability.
Life
History
­
2
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(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
Cannibalism
is
common
among
adults,
but
no
correlations
have
been
made
between
the
rate
of
cannibalism
and
abundance.
Growth
In
Dungeness
crabs,
like
other
crustaceans,
growth
proceeds
in
steps
through
a
series
of
molts.
The
number
of
molts
that
a
crab
undergoes
before
becoming
mature
depends
upon
the
increment
at
each
most
and
the
frequency
of
molting,
both
of
which
vary
among
crabs
at
different
locations.
Dungeness
crabs
grow
in
carapace
size
at
molt
and
gain
weight
between
molts.
Populations
of
0+
crabs
that
settle
directly
offshore,
as
well
as
1+
nearshore
crabs,
grow
significantly
slower
than
those
in
the
estuary.
Dungeness
crab
growth
is
quite
variable
along
the
Pacific
coast.
However,
in
general,
it
is
somewhat
slower
in
the
northern
part
of
the
range
(
Washington
and
British
Columbia)
when
compared
to
the
southern
part
of
the
range.*
86*

The
red
rock
crab,
Cancer
productus,
also
has
10
antero­
lateral
teeth;
frontal
teeth
are
unequal.
However,
this
species
differs
from
C.
magister
in
that
the
frontal
area
is
markedly
pronounced
beyond
outer
orbital
angles,
cheliped
fingers
are
black,
and
the
carapace
is
widest
at
eighth
antero­
lateral
tooth.
It
attains
a
width
of
7
inches.*
260*
The
rock
crab,
Cancer
antennarius,
like
C.
productus,
is
dark
red
with
black­
tipped
chelae,
is
widest
at
the
eighth
tooth,
but
red­
spotted
on
its
ventral
surface.
It
attains
a
width
of
about
13
cm.
Cancer
oregonensis
(
Oregon
Cancer
crab)
is
a
small,
oval
crab
with
12
antero­
lateral
teeth.
Both
the
slender
crab
(
Cancer
gracilis)
and
Cancer
jordani,
two
rather
uncommon
species,
have
nine
antero­
lateral
teeth;
C.
gracilis
rarely
exceeds
a
width
of
8
cm.
The
yellow
crab,
Cancer
anthonyi,
which
is
found
south
of
Humboldt
Bay,
have
large
smooth
claws
with
black
tips,
is
yellowish­
brown
with
a
wash
of
purple
anteriorly,
has
9
antero­
lateral
spines
and
attains
a
width
of
15
cm.*
260*

REPRODUCTION:
Dungeness
crabs
mate
from
April
to
September
in
British
Columbia,
mostly
in
March
and
April
but
sometimes
in
May
and
June
in
Washington;
and
March
to
July
in
California.
Mating
occurs
in
nearshore
coastal
locations
in
the
west
coastal
region
of
the
Pacific
Northwest.
Premolt
female
crabs
are
located
by
adult
males
for
mating,
possibly
through
a
pheromonal
homing
system
similar
to
those
used
by
other
crab
species.
The
female
is
held
by
the
male
in
a
premating
embrace
up
to
7
days
prior
to
her
molting.
Approximately
1
h
after
molting
of
the
female
is
completed,
the
hardshell
male
and
softshell
female
mate.
The
male
gonopods
are
inserted
into
the
spermathecae
of
the
female
and
spermatophores
are
deposted.
Following
copulation,
the
female
may
be
embraced
again
by
the
male
for
a
period
of
up
to
2
days.
Both
premating
and
postmating
embraces
may
serve
to
protect
the
female
from
predation,
while
insuring
the
mating
success
of
the
male
by
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guarding
the
female
against
other
males.
The
male
spermatophores
in
the
spermathecae
contain
sperm
that
may
be
viable
for
many
months,
often
through
molting
until
a
second
egg
extrusion.*
260*
Eggs
and
Fecundity.
Actively
molting
female
crabs
are
more
fecund
than
non­
molting
crabs,
even
though
they
may
be
the
same
size.
Eggs
are
not
fertilized
until
extrusion,
at
which
time
they
are
attached
to
the
female
pleopod
setae
and
are
carried
beneath
the
abdominal
flap;
they
hatch
in
60
to
120
days.
Eggs
are
extruded
from
September
to
February
in
British
Life
History
­
3
(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
Columbia,
from
October
to
December
in
Washington,
from
October
to
March
in
Oregon,
and
from
September
to
November
in
California.
An
egg
mass
may
contain
from
one
to
two
million
eggs,
and
a
female
may
produce
up
to
five
million
eggs
in
three
or
four
broods
during
her
lifetime.
Eggs
are
orange
at
extrusion,
becoming
progressively
darker
in
color
as
they
develop.
Water
temperatures
and
changes
in
water
temperatures
have
considerable
influence
on
the
rate
of
egg
development
and
mortality
after
fertilization
and
spawning.
When
temperatures
rise,
the
rate
of
egg
development
also
rises,
but
so
does
the
rate
of
mortality.
In
laboratory
tests
eggs
held
at
9.4
degrees
C
hatched
in
123
days
and
at
16.7
degrees
C
they
hatched
in
64
days.
At
10
degrees
C,
685,000
larvae
were
produced
per
egg
mass,
whereas
at
16.7
degrees
C,
14,000
larvae
were
produced
per
egg
mass.
Egg
mortality
for
eggs
from
Similk
Bay,
Washington,
was
20%
after
20
min
exposure
at
10
degrees
C,
30%
after
4
min
and
90%
after
20
min
at
15
degrees
C,
and
100%
after
4
min
at
20
degress
C.*
260*
Epibiotic
fouling
of
Dungeness
crab
eggs
has
been
linked
to
increased
egg
mortality
because
of
mechanical
interference
with
hatching
and
oxygen
consumption.
Waters
with
high
and
rising
nutrient
levels
are
suspected
to
cause
increased
fouling.
Egg
predation
by
a
nemertean
worm,
Carcinonemertes
errans,
is
thought
to
increase
the
fouling
of
eggs
through
the
liberation
of
yolk
during
its
feeding
and
defecation.
In
coastal
waters
near
San
Francisco,
the
estimated
average
annual
mortality
caused
by
predation
of
the
worm
on
Dungeness
crab
eggs
was
over
55%
in
1974­
1979
when
worm
densities
were
about
14
per
1,000
eggs.*
260*
Eggs
hatch
in
2
to
3
months.
The
hatching
season
commonly
shortens
from
north
to
south
along
the
Pacific
coast.
Eggs
hatch
in
coastal
waters
from
December
to
June
in
British
Columbia,
but
considerably
later
in
Queen
Charlotte
Islands,
from
January
to
April
in
Washington,
from
December
to
April
in
Oregon,
from
January
to
early
March
in
northern
California,
and
commonly
from
late
December
to
early
February
in
central
California.*
260*

LIMITING
FACTORS:
Predation.
The
larvae
are
preyed
upon
by
numerous
fishes.
Adults
and
juveniles
are
preyed
upon
by
sea
otters,
fishes,
and
octopuses.
Cannibalism
is
common
and
probably
exercises
some
control
over
abundance.*
260*
Temperatures.
Hatching
success,
considered
as
the
number
of
larvae
that
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hatch
from
an
egg
mass,
decreased
as
the
temperature
increased
from
10
to
17
degrees
C.
Researchers
found
a
similar
correlation
between
egg
mortality
and
temperature
with
20%
mortality
after
20
min
at
10
degrees
C
and
100%
mortality
after
4
min
at
20
degrees
C.*
260*
Temperature­
Salinity
Interactions.
At
favorable
temperatures,
unfavorable
salinities
resulted
in
complete
mortality
of
adults,
but
favorable
salinities
at
unfavorable
temperatures
allowed
some
survival.
The
effects
of
temperature
or
salinity
alone
on
C.
magister
zoeae
do
not
appear
to
cause
large
fluctuations
in
zoeal
survival
in
the
ocean.*
260*

POPULATION
ATTRIBUTES:
Growth
Characteristics.
In
Dungeness
crabs,
like
other
crustaceans,
growth
proceeds
in
steps
through
a
series
of
molts.
The
number
of
molts
that
a
crab
undergoes
before
becoming
mature
depends
upon
the
growth
increment
at
each
molt
and
the
frequency
of
molting,
both
of
which
vary
among
crabs
at
different
locations.
Dungeness
crabs
grow
in
carapace
size
at
each
molt
and
gain
biomass
between
molts.
In
older
crabs
the
growth,
as
measured
by
the
Life
History
­
4
(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
percent
change
in
carapace
width,
declines
as
the
frequency
of
molting
slows
down,
but
the
rate
of
weight
gain
increases
over
time.
The
probability
of
annual
molting
in
female
Dungeness
crabs
declines
from
about
1.0
for
crabs
of
130­
135
mm
CW
to
0.0
for
crabs
of
155
mm
CW
and
larger.
Among
possible
attributes
of
estuarine
residence
suggested
by
researchers
is
an
enhanced
growth
rate
compared
to
that
of
siblings
of
a
year
class
that
settle
offshore.
Size
attained
by
juvenile
crabs
within
certain
periods
after
metamorphosis
seems
to
be
somewhat
dependent
on
latitude
and
on
time
of
settlement.
Upper
estimates
of
age
at
sexual
maturity
range
from
4­
5
years
in
British
Columbia
to
1
year
in
San
Francisco
Bay,
where
the
crabs
reach
by
this
time
a
carapace
width
(
100
mm)
usually
associated
with
sexual
maturity.
More
generally,
crabs
are
predicted
to
reach
maturity
at
the
end
of
their
second
year
after
metamorphosis
or
in
their
third
growing
season
over
much
of
the
coast.
While
age
and
size
at
sexual
maturity
may
not
differ
substantially
along
the
coast,
estimates
of
growth
rates
of
newly
settled
age
0+
crabs
do.
Several
studies
of
juveniles
indicate
that
growth
rate
is
accelerated
in
estuaries
or
within
nearshore
coastal
embayments
where
water
temperatures
are
relatively
high.
This
difference
in
growth
raye
may
be
due
to
a
temperature
difference
which
is
approximately
6
degrees
C
higher
in
the
estuary
than
the
ocean.
Growth
of
young­
of­
the­
year
crabs
is
substantially
slower
offshore
from
San
Francisco
Bay,
in
the
Gulf
of
the
Farallons,
than
in
estuaries,
where
the
offshore
crabs
are
about
28­
30
mm
and
those
in
the
estuary
are
about
60
mm
in
width.
Gulf­
reared
crabs
require
about
2
years
after
metamorphosis
to
reach
the
first
postlarval
instar
width
of
100
mm,
while
the
average
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bay­
reared
crab
reaches
this
size
one
year
after
metamorphosis.
Growth
of
California
Dungeness
crabs
is
somewhat
faster
in
males
than
females,
but
varies
from
year
to
year
and
among
geographic
regions.
In
northern
California,
age
and
growth
are
similar
to
that
observed
in
Washington,
where
crabs
become
fully
recruited
into
the
fishery
at
4
years
of
age,
having
reached
a
carapace
width
of
about
159
mm.
Dungeness
crab
growth
is
variable
along
the
Pacific
coast.
However,
in
general,
it
is
somewhat
slower
in
the
northern
part
of
the
range
when
compared
to
the
southern
part
of
the
range
(
California).*
260*

Commercial
Fishery.
Commercial
landings
of
Dungeness
crab
on
the
Pacific
coast
have
fluctuated
widely,
almost
cyclically,
over
the
past
30
years.
Several
hypotheses
have
been
proposed
to
explain
the
cyclic
nature
of
Dungeness
crab
population
size.
According
to
researchers,
commercial
landings
were
highest
1.5
years
after
a
period
of
strong
upwelling
in
California
and
Oregon,
and
6
months
following
a
strong
upwelling
in
Washington,
although
the
biological
sense
of
such
a
relation
is
much
in
doubt.
Researchers
challenged
this
conclusion
by
using
auto­
correlation
to
show
that
commercial
landings
are
cyclic
but
that
strong
upwelling
is
not.
Another
hyposthesis
to
explain
catch
fluctuations
suggests
that
periods
of
high
levels
of
cannibalism
and
interspecific
competition
may
cause
a
decline
in
the
fishery
3
or
4
years
later.
In
a
model
predicting
recruitment,
researchers
discounted
cannibalism
as
a
factor
and
contended
that
changes
in
egg
and
larval
survival
regulate
population
success.
Larval
survival
may
be
seriously
reduced
by
a
combination
of
environmental
factors
that
can
cause
increased
mortality
if
unfavorable
for
even
short
periods
of
time.
Researchers
indicated
that
diseases
caused
by
various
organisms
(
bacteria,
Life
History
­
5
(
DRAFT)
­
Life
History
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
Protozoa,
or
fungi)
may
be
reponsible
for
mass
mortalities
of
adult
crabs.
Predation
may
have
a
profound
impact
on
the
Dungeness
crab
commercial
fishery
in
certain
geographic
areas.
Researchers
hypothesized
that
extensive
predation
by
hatchery­
released
coho
salmon
from
the
Columbia
River
continually
suppressed
the
Dungeness
crab
fishery.
There
is
an
apparent
cyclic
covariance
between
abundances
of
salmon
and
Dungeness
crabs.
Only
male
crabs
6­
1/
4
inches
wide
or
wider
may
be
taken
commercially
in
California.
Not
more
than
1%
of
any
catch
may
be
smaller
than
this
size
and
no
crabs
less
than
5­
3/
4
inches
may
be
retained.
Most
crabs
taken
in
the
California
commercial
fishery
are
4­
year­
olds,
although
some
3­
and
5­
year­
old
crabs
are
taken.*
260*

REFERENCES
FOR
LIFE
HISTORY­
86
and
260
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Life
History
­
6
(
DRAFT)
­
Management
Practices
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
MANAGEMENT
PRACTICES
RESULT
MANAGEMENT
PRACTICE
Existing
Other
management
practices
[
specified
in
comments]
Beneficial
Controlling
pollution
[
thermal,
chemical,
physical]
Existing
Regulating
harvest
of
species
being
described
Existing
Regulating
harvest
­
setting
size
limits
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REFERENCES
FOR
BENEFICIAL
MANAGEMENT
PRACTICES
­
255
REFERENCES
FOR
EXISTING
MANAGEMENT
PRACTICES
­
86
and
260
COMMENTS
ON
MANAGEMENT
PRACTICES
­
The
State
of
Oregon
has
sought
to
limit
the
conflict
between
sport
and
commercial
crabbers
by
restricting
commercial
crabbing
to
the
middle
of
the
week
and
to
the
use
of
sport
gear.*
86*
Another
theory
to
explain
catch
fluctuations
suggests
that
periods
of
high
levels
of
cannibalism
and/
or
interspecific
competition
may
cause
a
decline
in
the
fishery
3
or
4
years
later.
Larval
survival
may
be
seriously
altered
by
a
combination
of
environmental
factors
that
can
cause
increased
mortality
if
unfavorable
for
even
short
periods
of
time.
Disease
may
also
be
caused
by
various
organisms
(
bacteria,
protozoa,
or
fungi)
that
may
in
turn
cause
mass
mortalitites
of
adult
crabs.
Predation
may
have
a
profound
impact
on
the
Dungeness
crab
commercial
fishery
in
certain
geographic
area.
It
is
theorized
that
hatchery
released
coho
salmon
from
the
Columbia
River
continue
to
suppress
the
Dungeness
crab
fishery
through
extensive
predation.*
86*
The
effect
of
urban
pollution­
chlorine
residuals,
heavy
metals,
chlorinated
pesticides,
PCB's
and
hydrocarbons­
on
Dungeness
crabs
is
not
clear,
but
sublethal
effects
are
indicated
for
some
pollutants
at
concentrations
presently
occurring
in
San
Francisco
Bay.
Crabs
are
intolerant
of
low
dissolved
oxygen
(
optimal
>
5
ppm).
Ammonia
is
toxic
at
low
concentrations.
The
insecticide
Sevin
(
carbaryl)
is
sometimes
used
to
control
ghost
shrimp
in
Pacific
oyster
beds
but
is
also
very
toxic
to
Dungeness
crabs.
Zoea
of
C.
magister
are
the
most
sensitive
life
stages
to
insecticides
and
fungicides.*
255*
Recent
studies
on
the
environmental
consequences
of
dredging
in
estuaries
have
established
a
strong
probability
that
the
Dungeness
crab
population
will
be
seriously
reduced
by
habitat
alteration
from
dredging
unless
proper
precautions
are
taken
to
reduce
losses.
The
loss
of
vital
estuarine
habitat
could
significantly
reduce
recruitment
to
the
offshore
fishery.*
260*
Only
male
crabs
6­
1/
4
inches
wide
or
wider
may
be
taken
commercially
in
California.
Not
more
than
1%
of
any
catch
may
be
smaller
than
this
size
and
no
crabs
less
than
5­
3/
4
inches
may
be
retained.
Most
crabs
taken
in
the
California
commercial
fishery
are
4­
year­
olds,
although
some
3­
and
5­
year­
old
crabs
are
taken.*
260*
In
California
sport
fishery
the
daily
catch
limit
is
10
crabs.
Concern
over
the
excessive
take
of
sublegal
sized
Dungeness
crabs
in
the
sport
fishery
prompted
the
California
Fish
and
Game
Commission
in
1978
to
close
the
fishery
in
San
Francisco
and
San
Pablo
Bays
inside
Golden
Gate.
Sport
fishing
for
Dungeness
crabs
is
most
active
in
the
Crescent
City
area.
Management
Practices
­
1
(
DRAFT)
­
Management
Practices
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
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Nearly
4
times
more
red
crabs
(
C.
productus)
than
Dungeness
crabs
are
taken
in
the
sport
fishery.
Rock
crabs,
slender
crabs,
and
yellow
crabs
are
also
taken
in
the
sport
fishery
in
limited
numbers.*
260*

Management
Practices
­
2
(
DRAFT)
­
References
Species
crab,
dungeness
Species
Id
M070001
Date
26
AUG
96
file:///
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2372b.
htm
References
86*
Pauley,
G.
B.,
D.
A.
Armstrong,
T.
W.
Heun.
1986.
Species
profiles:
life
histories
and
environmental
requirements
of
coastal
fishes
and
invertebrates
(
Pacific
Northwest)­­
Dungeness
Crab.
U.
S.
Fish
and
Wildl.
Serv.
Biol.
Rep.
82(
11.63).
U.
S.
Army
Corps
of
Engineers,
TR
EL­
82­
4:
20.

11323*
Armstrong,
D.
A.,
B.
G.
Stevens,
J.
C.
Hoeman.
1982.
Distribution
and
abundance
of
Dungeness
crab
and
Crangon
shrimp,
and
dredging­
related
mortality
of
invertebrates
and
fish
in
Grays
Harbor,
Washington,
U.
S.
Army
Corps
of
Engineers,
Seattle.
Tech.
Rep.
Contract
No.
N­
NACW67­
80­
C0086:
349.

255
*
Monaco,
M.
E.,
R.
L.
Emmett.
1988.
National
Estuarine
Inventory:
Estuarine
Living
Marine
Resources
Project
Washington
State
Component.
Living
Marine
Resources
Program
(
ed.).
National
Oceanic
and
Atmospheric
Administration
Rockville,
MD:
82.

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OCKETS/
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2372b.
htm
References
­
1
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