Library

National Wetlands Research Center

QL

155

.S63

no. 82

11.46

Biological Report 82(11.46)

April 1986

Ll. S. F.sh 3. ~spyyl~p

700 Cajundome Boulevard

Lafayette, La. 70506 TR EL-82-4

Species Profiles: Life Histories and

Environmental Requirements of Coastal Fishes

and Invertebrates (Pacific Southwest)

COMMON LITTLENECK CLAM

Fish and Wildlife Service

U.S. Department of the Interior

Coastal Ecology Group

Waterways Experiment Station

U.S. Army Corps of Engineers

Biological Report 82t11.46)

TR EL-82-4

April 1986

Species Profiles: Life Histories and Environmental Requirements

of Coastal Fishes and Invertebrates (Pacific Southwest)

COMMON LITTLENECK CLAM

William N. Shaw

Humboldt State University

Fred Telonicher Marine Laboratory

Trinidad, CA 95570

Project Manager

Carroll Cordes

Project Officer

John Parsons

National Coastal Ecosystems Team

U.S. Fish and Wildlife Service

1010 Gause Boulevard

Slidell, LA 70458

Performed for

Coastal Ecology Group

Waterways Experiment Station

U.S. Army Corps of Engineers

Vicksburg, MS 39180

and

National Coastal Ecosystems Team

Division of Biological Services

Research and Development

Fish and Wildlife Service

U.S. Department of the Interior

Washington, DC 20240
This series should be referenced as follows:

U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life histories

and environmental requirements of coast3 fishes and invertebrates. U.S. Fish

Wildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL-82-4.

This profile should be cited as follows:

Shaw, W.N. 1986. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Southwest)--common

littleneck clam. U.S. Fish Wildl. Serv. Biol. Rep. 82(11.46). U.S. Army Corps

of Engineers, TR EL-82-4. 11 pp.
PREFACE

This species profile is one of a series on coastal aquatic organisms,

principally fish, of sport, commercial, or ecological importance. The profiles

are designed to provide coastal managers, engineers, and biologists with a brief

comprehensive sketch of the biological characteristics and environmental

requirements of the species and to describe how populations of the species may be

expected to react to environmental changes caused by coastal development. Each

profile has sections on taxonomy, life history, ecological role, environmental

requirements, and economic importance, if applicable. A three-ring binder is

used for this series so that new profiles can be added as they are prepared.

This project is jointly planned and financed by the U.S. Army Corps of Engineers

and the U.S. Fish and Wildlife Service.

Suggestions or questions regarding this report should be directed to one of

the following addresses.

Information Transfer Specialist

National Coastal Ecosystems Team

U.S. Fish and Wildlife Service

NASA-Slide11 Computer Complex

1010 Gause Boulevard

Slidell, LA 70458

or

U.S. Army Engineer Waterways Experiment Station

Attention: WESER-C

Post Office Box 631

Vicksburg, MS 39180

iii
Multiply EY To Obtain

millimeters (mn)

centimeters (an)

meters (m)

kilometers (km)

square meters (m')

square kilometers (km2)

hectares (ha)

0.03937 inches

0.3937 inches

3.281 feet

0.6214 miles

10.76 square feet

0.3861 square miles

2.471 acres

liters (1)

cubic meters (m3)

cubic meters

0.2642 gallons

35.31 cubic feet

0.0008110 acre-feet

milligrams (mg) 0.00003527

grams (9) 0.03527

kilograms (k )

9

2.205

metric tons t) 2205.0

metric tons 1.102

kilocalories (kcal) 3.968

ounces

ounces

pounds

pounds

short tons

British thermal units

Celsius degrees 1.8(V) + 32 Fahrenheit degrees

inches 25.40 millimeters

inches 2.54 centimeters

feet (ft) 0.3048 meters

fathoms 1.829 meters

miles (mi) 1.609 kilometers

nautical miles (rmi) 1.852 kilometers

square feet (ft2)

acres

square miles (mi2)

0.0929 square meters

0.4047 hectares

2.590 square kilometers

gallons (gal) 3.785

cubic feet (ft3) 0.02831

acre-feet 1233.0

liters

cubic meters

cubic meters

ounces (02)

pounds (lb)

short tons (ton)

28.35

0.4536

0.9072

British thermal units (Btu) 0.2520

Fahrenheit degrees 0.5556("F - 32)

grams

kilograms

metric tons

kilocalories

Celsius degrees

CONVERSION TABLE

Metric to U.S. Customary

U.S. Customary to Metric

iv
CONTENTS

Page

PREFACE . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lll

CONVERSION TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

NOMENCLATURE/TAXONOMY/RANGE .................................................... 1

MORPHOLOGY/IDENTIFICATION AIDS ................................................. 1

REASON FOR INCLUSION IN SERIES ............................................... 3

LIFE HISTORY ................................................................. 3

Spawning ..................................................................... 3

Eggs and Larval Stages ....................................................... 4

Postlarvae and Recruitment ................................................... 4

Maturity and Life-Span ....................................................... 4

GROWTH CHARACTERISTICS .......................................................

COMMERCIAL AND SPORT FISHERIES ............................................... :

AQUACULTURE .................................................................. 6

ECOLOGICAL ROLE .............................................................. 7

ENVIRONMENTAL REQUIREMENTS ...................................................

Temperature and Salinity ..................................................... :

Substrate .................................................................... 8

Depth ........................................................................ a

Other Environmental Factors .................................................. a

LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

V
ACKNOWLEDGMENTS

Much appreciated are the reviews by Kenneth K. Chew, University of Washington, and Howard M. Feder, University of Alaska. Thomas Hassler, California Cooperative Fishery Research Unit, kindly acted as the liaison with the National

Coastal Ecosystems Team and greatly facilitated the completion of this report;

Carol Wardrip of the Fred Telonicher Marine Laboratory also gave valuable assistance. David Moran served as Assistant Project Officer.

vi
Figure 1. Common littleneck clam.

COMMON LITTLENECK CLAM

NOMENCLATURE/TAXONOMY/RANGE

Scientific name . . . . . . . . . . ..Protothaca

staminea (Conrad)

Preferred common name . . . . . . . . ..Common

littleneck clam (Figure 1)

Other common names . . . . . . . . . . ..Native

littleneck clam, rock bay

cockle, hardshell clam, Tomales Bay

cockle, rock clam, ribbed carpet

shell, steamer

Class . . . . . . . . . . . . . . . . . . . ..Pelecypoda

Order . . . . . . . . . . . . . . . . . . . . ..Veneroida

Family . . . . . . . . . . . . . . . . . . . . . Veneridae

Geographic range: Aleutian Islands,

Alaska, south to Cape San Lucas,

Baja California, Mexico; commercially abundant only north of

Oregon. In California, the

coastal waters near San Onofre,

San Diego County (Figure 21,

probably are the most productive

area for clams in California

(Frey 1971). Other concentrations

are near Malibu Point and San

Mateo Point south of San Clemente, California, and Bodega and

Tomales Bays north of San Francisco. The clam is relatively

scarce in northern California.

MORPHOLOGY/IDENTIFICATION AIDS

The following descriptions are

extracted from Fitch (1953). The

shell is oval and has inflated valves

ornamented by well-defined, radiating

ribs and less prominent, concentric

ridges. Lunule (heart-shaped impression anterior to umbo) often is only

faintly defined. The ventral margin

is slightly crenulated. The pallial

sinus (U-shaped indentation) extends

1
BODEQA BAY

TOYALES BAY

SAN FRANCISCO BA

MONTEREY“

BAY

i

I

I

:

I

*\

\

\

I

\

*

‘Y\

\

\

‘\

,

‘\\

‘1 \

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‘,

‘\

CALIFORNIA

MALIBU PT.’ LOS ANGELES

Coastal diatrlbution

Q

\

\

\

‘\

DIEGO

,

Figure 2. Distribution of the littleneck clam along the California coast.

Greatest recorded abundance is at San Onofre, San Diego County (Frey 1971).

2
slightly more than half way to

anterior adductor muscle. Color is

highly variable: yellowish grey or

grey if in sloughs and bays; often

whitish with geometric patterns of

wavy brown lines or blotches on sides

of specimens along the open coast.

The clam attains a length of 6.4 cm.

It differs from chione clams (Chione

spp.) and Japanese littleneck-

(Tapes japonica) in having a pallial

sinus extending more than half way to

the anterior adductor muscle, and from

the rough-sided clam (Protothaca

laciniata) and thin-shelled littleneck

clam (1. tenerrima) in having

radiating ribs more prominent than

concentric ridges.

REASON FOR INCLUSION IN SER IES

The littleneck clam,

common in bays and estuar

cobble patches along the

California, supports an

sport shell fishery.

relatively

ies and in

coast of

important

Because the littleneck clam

lives in shallow bays with mud and

sand bottoms, the habitat of this

species in California is especially

vulnerable to degradation because of

harbor development, dredging, and

pollution. For example, the waters of

San Francisco Bay are so polluted in

some areas that depuration is

necessary before these and other clams

can be eaten (Ritchie 1977).

The Japanese littleneck clam,

apparently introduced with shipments

of Pacific oyster seed, is rapidly

replacing the common littleneck clam

in San Francisco and Tomales Bays

(Smith and Kato 1979; J.T. Carlston,

William College, Mass., pers. comm.).

A habitat suitability index model of

the littleneck clam also has been

prepared by the U.S. Fish and Wildlife

Service (Rodnick and Li 1983).

LIFE HISTORY

Soawning

The sexes of the common

littleneck clam are separate (Quayle

1943). The time of spawning varies

throughout its range, depending

largely on water temperature. Early

studies in British Columbia report

spawning in January (Fraser 1929) and

in February and March (Fraser and

Smith 1928). On Wood Island, British

Columbia, the tubules of the ovary are

filled with follicular cells in

December and January (Quayle 1943).

The growth of gametes reaches a peak

in March and spawning begins in April.

Few spawn later than September. The

male spawning cycle parallels that of

the female, but for unknown reasons

lags behind that of the female by

about 1 month. In British Columbia,

most clams spawn in late spring but

some may spawn off and on throughout

the summer (Quayle and Bourne 1972).

In Alaska, spawning starts in

mid-July when the water temperature is

about 8' C (Glude 1978). In Prince

William Sound, Alaska, spawning begins

in late May to mid-June and continues

into September (Nickerson 1977). In

summer, water temperature fluctuations

are unusually strong, so there may be

two periods of high temperature and

two corresponding spawning peaks. In

a warmer than normal year, only one

temperature and spawning peak may be

expected.

In Mugu Lagoon, California,

Peterson (1982) reported that June

marks the beginning of the season of

gamete release. He also observed that

Protothaca's gonad weight declined

SharDlv between June and December.

indicating spawning between June and

December. From studies conducted by

Peterson and Quammen (lg82), it

appears that initial setting may occur

as early as mid-April.

During spawning, the eggs and

sperm are discharged through the

3
c ’

siphon (Quayle and Bourne 1972) and

mass fertilization takes place in the

open water.

Eqgs and Larval Stages

The embryos develop into a

trochophore larval stage (60-80 pm)

about 12 h after fertilization (Quayle

and Bourne 1972). The veliger

(straight-hinge stage) develops in the

next 24 h. A ciliated velum develops

and helps the larva swim and maintain

itself in the upper part of the water

column. Larvae feed on phytoplankton

and are about 0.15 mm long after 1

week. The veligers develop an umbo

(prodissoconch) and may reach a length

of 0.26 to 0.28 mm in 2 weeks. Fraser

(1929) found larvae up to 0.5 mm long

in British Columbia. Prior to

metamorphosis, the veligers develop a

foot and an eye spot, move to the

bottom, and search for a suitable

surface on which to settle. Once a

suitable surface is found, the larvae

undergo metamorphosis and attach to

the surface by secreting byssal

threads. Depending on food supply and

temperature, the planktonic larval

stage generally lasts about 3 weeks

(Quayle and Bourne 1972).

The larval stage is a critical

one and breeding success or failure is

frequently determined at this time

(Quayle and Bourne 1972). Larvae are

at the mercy of currents and may be

carried away from settling areas and

perish.

Postlarvae and Recruitment

Postlarvae are epifaunal and

mortality may be high (Paul and Feder

1973). After settlement, mortality is

highest during or at the end of the

first year (Schmidt and Warme 1969).

Highest mortality is in the winter.

In Mugu Lagoon, California,

clams that had set in mid-April in

sand were 7.6 mn long by mid-June

whereas those in mud were 8.3 mn long

by mid-June (Peterson 1982). Unlike

the Washington clams, Saxidomus, which

remain permanently at site of

settlement, young littleneck clams can

crawl, using their foot, to other

areas.

The extent of annual recruitment

of littleneck clams varies greatly

between areas. Peterson (1975) found

that Protot- had the highest

variance in numbers of all species

collected in 10 sampling periods over

a 3-year period, suggesting a high

variability in recruitment. In sand,

experimentally increased adult

densities had no significant effect on

recruitment, whereas in mud, high

adult densities reduced recruitment up

to 60%. In Prince William Sound,

Alaska, the clam's northern limit,

recruitment was erratic and there was

little recruitment from 1967 to 1971,

probably due to poor spawning

conditions (Paul and Feder 1973; Paul

et al. 1976a).

mitv and life-Span

The only data on maturity are

from north Pacific populations. At

Woods Island, Ladysmith Harbor,

British Columbia, sexual differentiation was apparent when clams were 15

to 35 mm long or during their second

or third year of life (Quayle 1943).

Mature clams were usually 22 to 35 ~ma

long. At Prince William Sound,

Alaska, the youngest sexual mature

clam was 3 years old and 13 mn long

(Nickerson 1977). . .

Columbia, Fraser and St?th ";~~~~!

found some mature 2-year-old clams;

about one-half of the clams spawned

for the first time at the end of the

second year of life (25 mn long).

The life span of the littleneck

clam varies among different locations.

Their life span in years, their

lengths, their location, and the

authors are as follows: 13 years

(62 rmn), Porpoise Island, Alaska (Paul

et al. 1976b); 10 years (54 to 63 nm),

British Columbia, Canada (Frager and

Smith 1928; Quayle and Bourne 1972);

i

ui

I

4
16 years (42 to 50 ma), Olson Bay,

Prince William Sound, Alaska (Paul et

al. 1976a); 15 years, Galena Bay,

Prince William Sound, Alaska (Paul and

Feder 1973; Nickerson 1977); and 7

years, Mugu Lagoon, California

(Schmidt and Warme 1969).

GROWTH CHARACTERISTICS

Some scientists believe that

littleneck clams can be accurately

aged by counting the rings on the

shell (see Figure 1). The rings are

much closer together when growth slows

in the winter because of low

metabolism. Hughes and Clausen

(19801, however, expressed caution

about aging littleneck clams by shell

rings. They observed excessive

variation in ring patterns among

specimens in the same population from

Newport Bay, Oregon. Fraser and Smith

(1928) also reported that

disturbance that interrupts growth t!%

cause ring formation. Rings can be

evaluated as an aging tool by marking

the shell and then recovering the

clams for examination at a later date

(Paul and Feder 1973).

The growth of littleneck clams

varies throughout its range. Growth

curves are available for clam populations from Alaska, British Columbia,

and California (Figure 3) and for an

experimental plot in Oregon (Figure

4).

Alaska,

In Prince William Sound,

clams reach the marketable

length of 30 mm in 8 years (Feder and

Paul 1973; Paul and Feder 1973), but

at Porpoise Island, southeast Alaska,

clams reach this length in 4 to 5

years (Paul et al. 1976b). In waters

near Sidney, British Columbia, the

range of length of the clams for each

year of life was as follows: 1st

year, 11-17 mm; 2nd year, 22-33 mm;

3rd year, 36-51 mm; 4th year, 37-51

; 5th year 43-55 mm; 6th year,

Z-57 mm; 7tA year 47-60 mm; 8th

year, 49-61 mm; gth'year, 51-62 mm;

and 10th year, 54-63 mm (Fraser and

Smith 1928). The authors reported

60

50

40

z

230

s

2

+zo

IO

0

I 2 3 4 5 6 7 8 9 IO I I 12 I3

Age (ye*rd

Figure 3. Ages and corresponding

shell lengths (mm) of the common

littleneck clam from (A) Porpoise

Island, southeast Alaska; (B) Galena

Bay, Prince William Sound, Alaska;

(C) Victoria, British Columbia, Canada

(Paul et al. 1976b); (D) Strait of

Georgia, British Columbia, Canada

(Quayle and Bourne 1972); and (E) Mugu

Lagoon, California (Schmidt and Warme

1969).

-2

E40 -

c

c”

030

=

:

*20 -

2

I

IO -

6 I2 I8 24 36 36 42

Time (month81

Figure 4. Growth curve of littleneck

clams planted in an artificial substrate plot, Yaquina Bay, Oregon

(Lukas l(9S7yt over a period of 38

months

1973).

e . 30, 1970-April 12,

5
wide differences in growth rates among

the years.

In Mugu Lagoon, California, the

growth rate of littleneck clams was

consistently depressed at experimentally induced high intraspecific

densities. In mud the clam's linear

growth declined more than in sand as

intraspecific density increased

(Peterson 1982). In Alaska, clams at

the higher tide levels had the best

growth (Nickerson 1977). At Kiket

Island, Washington, however, the best

growth was near mean lower low water

and less rapid at higher and lower

tide levels. Growth was better on the

north side of the island because of

more stable water temperatures and

salinities (Houghton 1977).

In British Columbia littleneck

clams are 37 mn long in 3.5 to 4 years

and 63 mn long in 10 years (Glude

1978). In the State of Washington, it

takes 4 to 6 years for clams to reach

commercial length (1.5 inches). In

Oregon, clams planted on artificial

substrate (Figure 4) were 37 mm long

in 42 months (Lukas 1973). In

California, clams reach legal size

(1.5 inches) in 2 years (Frey 1971),

although in Mugu Lagoon (Figure 3) it

appears to take up to 7 years to reach

legal size.

COMMERCIAL AND SPORT FISHERIES

Littleneck clams are of

commercial importance only in British

Columbia and Washington (Amos 1966).

The U.S. catch on the west coast in

1963 produced 214,400 lb of meat worth

$107,194. In British Columbia, the

annual commercial landings ranged from

21,300 to 521,900 lb in 1951-1969

(Quayle and Bourne 1972). Clams are

either dug with long-tined rakes or

with a hydraulic clam dredge. As many

as 2,500 clams per hour can be

collected by a clam dredge in areas of

high density (Nickerson 1977). The

clams are marketed fresh for steaming

as far south as San Francisco.

In California there was

commercial digging prior to World War

II, but now most of the beds have been

overexploited and only sport clamming

is permitted. San Francisco Bay is

the only large area in California nith

sufficient clam abundance to support a

commercial fishery (Ritchie 1977), but

because of pollution, all clams from

San Francisco Bay would have to be

depurated before sale. Because of

daily catch limit of 50 clams, a commercial fishery is unlikely to develop. Littleneck clams are not harvested

in Prince William Sound or elsewhere

in Alaska as a consequence of paralytic shellfish poison of PSP (Anonymous

1974). Eating shellfish that have

consumed large amounts of the poisonproducing microscopic dinoflagellate

Gonyaulax catenella can cause serious

illness (Nishitani and Chew 1983).

Sport clamming in California is

done by hand with a rake or shovel

(Frey 1971). Clam digging tends to be

concentrated in the intertidal areas

primarily during low tide. Fifty

clams yield about 1.5 lb of edible

meat.

The major problem of the sport

clam fishery in California is the

discharge of sewage and animal wastes

into estuaries and nearshore marine

waters (Ritchie 1977). Although there

is a coastwide warning of the dangers

of paralytic shellfish poison from May

1 to October 31, the poison is not a

problem.

AQUACULTURE

Littleneck clams are not

cultured on the west coast. Ritchie

(1977) concluded that clam farming

should be permitted in California only

in those areas where no other endemic

species of clams are present. Culture

under these restrictions would involve

some form of beach rehabilitation

and/or the planting of hatcheryproduced seed. In many areas,

residents might object to using public

b

6
lands for private benefit (Ritchie

1977). As a result of stringent State

laws (e.g., 50 clam limit/day) and

economic considerations, the potential

for littleneck clam culture in

California is low.

ECOLOGICAL ROLE

The littleneck clam is a

suspension feeder, collecting

everything in the plankton small

enough to be ingested (Schmidt and

Warme 1969). The size of particle

ingested is controlled by the size of

the mouth opening or the life stage.

Clam

P

ostlarvae

partic es

can feed only on

under 10 pm in diameter,

primarily benthic diatoms and perhaps

sediment bacteria (Peterson 1982).

Because most littleneck clams live in

the intertidal zone, most feeding is

at high tide.

Unlike many species of clams,

littlenecks can move by using their

foot (Peterson 19821 and reburrow

(Quayle and Bourne 1972). Clams in

heavily populated areas may move to

less densely populated areas, and

clams exposed by dredging can reburrow

after dredging is completed. Over 88%

of the clams less than legal size

reburrowed in both "soft" and "hard"

bottoms after exposure (Quayle and

Bourne 1972). Feder and Paul (19731

demonstrated the littleneck's ability

to reburrow through a mark and

recapture study.

Epizoic growth on littleneck

clams is rare; and Peterson (1982)

stated that fouling organisms are

either scraped off in reburrowing or

are smothered. No epidemic disease

has been found in littleneck clams

(Quayle and Bourne 1972). Two species

of tetraphyllidian cestodes were found

in littleneck clams in Humboldt Bay,

California, and littleneck clams often

contained large numbers of larval

tapeworms (Sparks and Chew 1966;

Warner and Katkansky 19691. These

parasites are killed by cooking and

cannot infect humans even when alive.

The littleneck clam has many

predators. In Mugu Lagoon,

California, Peterson (1982) observed

fatalities caused by the snail

Polinices reclusianus and the crab

Cancer anthonyi. Littleneck clams

make up -ofthe diet of the octopus

~;;~~us dofleini (Hartwick et al.

The clams eaten were 15 to

70 mm'long, but most were 40 to 50 mm

long. The intensity of predation was

related to distance between the den of

the octopus and the gravel beaches

where the clams lived.

Two carnivorous gastropods,

Forreria belcheri and Shaskyus

festivus, prey on littleneck clams

(Schmidt and Warme 1969). Sea stars

(Pycnopodia helianthoides) prey on

littleneck clams in Prince William

Sound, Alaska (Paul and Feder 1975).

The sea otter (Enhvdra lutris) also is

a major predator of clams (Feder and

Paul, University of Alaska; pers.

comm.1. Other predators are

polychaetes, fishes, and ducks (Quayle

and Bourne 19721. Small fishes have

been found to nip on the siphons of

littleneck clams, reducing clam

growth (Peterson and Quammen 1982).

In transplant experiments in

Mugu Lagoon, California, the deepdwelling bivalve Sanauinolaria

nuttallii has no discernible influence

on the shallow-dwelling littleneck

clam (Peterson and Andre 19801.

ENVIRONMENTAL REQUIREMENTS

Temperature and Salinity

Larval littleneck clams

live in a relatively narrow

temperature and salinity.

normally

range of

Near

Newport, Oregon, the optimum water

temperature range is 10 to 15 OC and

the optimum salinity range is 27 to

32 ppt (Phibbs 1971). Adult

littleneck clams can withstand water

7
temperatures from near freezing to

25 OC, and the salinity tolerance for

adults ranges from about 20 ppt or

less, to 30 ppt in Prince William

Sound, Alaska (Glude 1978).

Substrate

Littleneck clams live in the

coarse, sand to mud sediments of bays,

sloughs and estuaries in California

(Fitch 1953). On the open coast, they

live in nearly any area where there

are rocky points or reefs made up of

small cobbles over coarse sand. In

southeastern and south-central Alaska,

littleneck clams are common on sandy

gravel beaches. In some coastal

waters of California, there are wide

fluctuatJ;;;f:n clam abundance because

heavy from creeks causes

extensive sanding-in of cobble beaches

which decimates clam habitat (Frey

1971). Littleneck clam populations in

those areas that have undergone

sanding-in may require as many as 5

years to recover (Frey 1971).

Littleneck clams live often on

small beaches that exist in pockets on

rocky shorelines, or in small patches

of larger beaches (Fraser and Smith

1928). The best beaches for littleneck clams are those with coarse sand

or fine ravel mixed with mud, stones,

or she1 s. 9 Apparently littleneck

clams do poorly in fine sand.

Depth

Littleneck clams are most

abundant in the lower part of the

intertidal zone and subtidally to a

depth of 3 m (Glude 1978).

burrowing depth is about Yzrn

Quayle and Bourne (1972) observ2

littleneck clams from the lower three

quarters of the intertidal zone down

to a depth of 13 m. They stated that

clams burrow down to a maximum depth

of 16 cm. In Alaska, clams live in

the 1.5 to 1.0 m tidal range (Paul et

al. 1976a; Nickerson 1977).

Other Environmental Factors

Heavy metals have been

concentrated in littleneck clams

because long-lived sedentary animals

commonly concentrate such

contaminants. Littleneck clams are

highly sensitive to copper which is

used in antifouling boat paints

(Roesijadi 1980a, 1980b). A 15%

mortality of clams was reported at

copper concentrations of 7 and 18 pg/l

after 30 days of exposure. At 39 and

82 pg/l, mortality was 86% and 97%.

respectively, after 30 days of

exposure. Copper concentrates in the

gills and disrupts regulation of

cellular sodium and potassium.

The uptake of heavy metals in

littleneck clams has been monitored in

Elkhorn Slough, California (Graham

1972). Shell concentrations (ppm dry

weight) were as follows: Ag, 5.8; Cd,

2.9; Cr, (5.7; Cu, 11.5; Mn, 16.8; Pb,

<9.0; and Zn, 9.2. The quantities

(ppm) in the clam meat were as

follows: Ag, <l.O; Cd, 5.7; Cr, (1.5;

Cu, 7.5; Mn, 11.5; Pb, 5.2; and Zn,

67.7. The quantities of heavy metals

in the littleneck clam generally were

lower than those in other shellfish in

California. Crabs consumed more clams

from oiled than from unoiled sand

because clams do not burrow as deep in

oiled sand (Pearson et al. 1981).

Slow reburrowing in oiled sand also

led to increased predation. Small

clams are far more vulnerable to crab

predation than large ones.
LITERATURE CITED

Amos, M.H. 1966. Commercial clams of

the North American Pacific coast.

U.S. Fish Wildl. Serv. Circ. 237.

I8 PP.

Anonymous. 1974. Paralytic shellfish

poisoning and the law. Alaska Seas

Coasts 2(1):5.

Bureau of Marine Fisheries. 1949. The

commercial fish catch of California

for the year 1947 with an historical

review 1916-1947. Calif. Dep. Fish

Game Fish. Bull. 74. 267 pp.

Feder, H.M., 3.C. Hendee, P. Holmes,

G.J. Mueller, and A.J. Paul. 1979.

Examination of a reproductive cycle

of Protothaca staminea using histological, wet weight-dry weight

ratios, and condition indices.

Veliger 22(2):182-187.

Feder, H.M., and A.J. Paul. 1973.

Abundance estimations and growthrate comparisons for the clam

Protothaca staminea from three

beaches in Prince William Sound,

Alaska, with additional comments on

size-weight relationships, harvesting and marketing. Alaska Sea

Grant Program Rep. 73-2. 34 pp.

Fitch, J.E. 1953. Common marine

bivalves of California. Calif. Dep.

Fish Game Fish. Bull. 90. 102 pp.

Fraser, C.M. 1929. The spawning and

free swimming larval periods of

Saxidomus and

Sot. Can. Ser. 3,

Fraser, C.M., and GM. Smith. 1928.

Notes on the ecology of the little

neck clam, Paphia staminea Conrad.

Trans. R. Sot. Can. Ser. 3, 22:249-

269.

Frey, H.W. 1971. California's living

marine resources and their

utilization. Calif. Fish and Game,

The Resources Agency. 148 pp.

Glude, J.B. 1978. The clams genera

Mercenaria, Saxidomus, Protothaca,

Tapes, Ma Panooe, and Soisula a

literature review and analvsis of ~-“--

the use of thermal effluent in the

culture of clams. Aquaculture Consultant Rep. 74 pp.

Graham, D.L. 1972. Trace metal

levels in intertidal mollusks of

California. Veliger 14(4):365-372.

Hartwick, B., L. Tulloch, and S.

MacDonald. 1981. Feedina and

growth of Qctoous dofleini (Wujker).

Veliger 19(2):163-166.

Houghton, J.P. 1977. Age and growth

of Protothaca staminea (Conrad) and

Saxidomus qiqanteus (Deshayes) at

Kiket Island, Washington. Proc.

Natl. Shellfish. Assoc. 67:119.

(Abstr.)

Hughes, W.W., and C.D. Clausen. 1980.

Variability in the formation and

detection of growth increments in

bivalve shells. Paleobiology 614):

503-511.

Lukas, 6. 1973. Clam-abalone

spawning and rearing. Fish Commission of Oregon Completion Report for

;gh$3period July 1970-June 1973, July

. PL 89-304, Proj. 1-60-R. 24

PP.

9
Nickerson. R.B. 1977. A study of the

littleneck clam (Protothaca staminea

Conrad) and the butter clam=

domus qiqanteus Deshayes) in ahabitat permitting coexistence, Prince

William Sound, Alaska. Proc. Natl.

Shelfish. Assoc. 67:85-102.

Nishitani, L., and K.K. Chew. 1983.

Gathering safe shellfish in Washington. Wash. Sea Grant Program

Advis. Rep. 6 pp.

Paul, A.J., and H.M. Feder. 1973.

Growth, recruitment, and distribution of the littleneck clam,

Protothaca staminea, in Galena Sayi

Prince Willl'amd. Alaska. U.S.

Natl. Mar. Fish Serv. Fish. Bull.

71(3):665-677.

Paul, A.J., and H.M. Frder. 1975.

The food of the sea star P cno odia

w-11

helianthoides (Brandt) *

1;:1z2.

bound, Alaska. Ophelia

Paul, A.J., J.M. Paul, and H.M. Feder.

1976a. Recruitment and growth in

the bivalve Protothaca staminea, at

Olsen Bay, Prince William Sound, ten

years after the 1964 earthquake.

Veliger 18(4):385-392.

Paul, A.J., J.M. Paul, and H.M. Feder.

1976b. Growth of the littleneck

clam, Protothaca staminea, on

Porpoise Island, southeast Alaska.

Veliger 19(2):163-166.

Pearson, W.H., D.L. Woodruff, P.C.

Sugarman, and B.L. Olla. 1981.

Effects of oiled sediments on predation on littleneck clam, Protothaca staminea, by the dungeness

crab, Cancer maqister. Estuarine

Coastal Shelf Sci. 13(4):445-454.

Peterson, C.H. 1975. Stability of

species and community for the benthos of two lagoons. Ecology

56:958-965.

Peterson, C.H. 1982. The importance

of predation and intra- and interspecific competition in the population biology of two infaunal

suspension-feeding bivalves, Protothacg staminea and Chione &I&&-

u. Ecol. Monogr. 52(4):437-475.

Peterson, C.H., and S.V. Andre. 1980.

An experimental analysis of interspecific competition among marine

filter feeders in a soft-sediment

environment. Ecology 61(1):129-139.

Peterson, C.H., and M.L. Quammen.

1982. Siphon nipping: its importance to small fishes and its impact

on growth of the bivalve Protothaca

staminea (Conrad). J. Exp. Mar.

Biol. Ecol. 63:249-268.

Phibbs, F.D. 1971. Temperature,

salinity and clam larvae. Proc.

Natl. Shellfish. Assoc. 61:13.

(Abstr.)

Quayle, D.B. 1943. Sex, gonad development and seasonal gonad changes in

Paphia staminea Conrad. J. Fish.

Res. Board Can. 6(2):140-151.

Quayle, D.B., and N. Bourne. 1972.

The clam fishery of British Columbia. Fish. Res. Board Can. Bull.

179. 70 PP.

Ritchie, T.P. 1977. A comprehensive

review of the commercial clam industries in the United States. U.S.

Natl. Mar. Fish. Serv. 106 pp.

Rodnick, K., and H.W. Li. 1983.

Habitat suitability index model:

littleneck clam. U.S. Fish

Wildl. Serv. FWS/OBS-82/10.59. 15

PP.

Roesijadi, G. 19BOa. Influence of

copper on the gills of the littleneck clam Protothaca staminea.

Proc. Natl. Sh llfish.

70(1):129. (Abstr.e)

Assoc.

Roesijadi, G. 1980b. Influence of

copper on the clam Protothaca

staminea: effects on gl I Is and

occurrence o f copper-binding

10
proteins. Biol. Bull. (Woods Hole) Sparks, A.K., and K.K. Chew. 1966.

158:233-247. Gross infestation of the littleneck

clam (Venerupsis staminea) with the

Schmidt, R.R., and 3.E. Warme. 1969. larval cestode (Echeneibothrium

Population characteristics of Pro- sp.). J. Invertebr. Pathol. 8:413-

tothaca staminea (Conrad) from Mugu 416.

Lagoon, California. Veliger 12(2):

193-199.

Smith, S.E., and 5. Kato. 1979. The Warner, R.W., and S.C. Katkansky.

fisheries of San Francisco Bay: 1969. The infestation of the clam

past, present and future. Pages Protothaca staminea by two species

445-467 in T.J. Conomus, ed. San of Tetraphyllidian cestodes

Francisco- Bay, the unurbanized (Echeneibothrium SPP.). J.

estuary. Invertebr. Pathol. 13(1):129-133.

11
10771~101

,

REPORT DOCUMENTATION 1. “VCJRT NO.

; Biological Report 82(11.46)* I”

3. ~*ClDW@t’, ICC.,.,e” No

PAGE I 4. TPh ati Subtoth 9. Rwwl Date

Species Profiles: Life Histories and Environmental Requirements April 1986

of Coastal Fishes and Invertebrates (Pacific Southwest)--Common L

Fred Telonicher Marine Laboratory

12 sDontin( OfWnlutlm Nom. and Addnsl -(Cl

National Coastal Ecosystems Team U.S. Army Corps of Engineers It. TY# d nwon 4 l wiM _r?d

Fish and Wildlife Service Waterways Experiment Station

U.S. Department of the Interior P.O. Box 631

Washington, DC 20240 Vicksburg, MS 39180 14.

*U.S. Army Corps of Engineers Report No. TR EL-82-4

1L *kmcc (Umttz 200 words)

Species profiles are literature summaries of the taxonomy, morphology, distribution, life

history, and environmental requirements of coastal aquatic species. They are prepared to

assist in environmental impact assessment. Common littleneck clam (Protothaca staminea)

supports an important sport fishery in the Pacific Southwest Region, but has no commercial

importance. The species is distributed from Alaska to Baja, California. The egg develops

into the trochophore stage 12 h after fertilization , and the planktonic larval stage lasts

about 3 weeks. Adults usually mature in the second or third year of life. Mortality is

greatest early in life. Intraspecific competition among adults is more evident in mud

than in sand. Most littleneck clams live in the lower intertidal zone. Littleneck clams

concentrate heavy metals and are highly sensitive to copper.

17. *pac.um* hani

Life cycles

. . O*rcriptoon

Fisheries

Feeding habits

Growth

Sediments

Clams

Competition

Contaminants

Aquaculture

b. ldwtM~n/Open.Ended Terms

Ecological role

Common littleneck clam

Protothaca staminea

Environmental requirements

. . nl imited release

(Se* ANSlY9.19)

U.S.G.P.O. 1986/661-638

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