Library National Wetlands Research Center U. S. Fish and Wildlife Service 700 Cajundome Boulevard Lafayette. La. 70506

FWS/O BS-82/11.13 October 1983 TR EL-82-4 Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic) SURF

.6''

6 , *~ ~~'"

'I \' '~*

I '6'.

''I 0

* *7I) I' * II QL Ill ~ 0 155 0. .S63 no.82- 11.13

0 / 0 ~ 0 Coastal Ecology Fish and Wildlife Group Service Waterways Experiment Station U.S. Department of the Interior U.S. Army Corps of Engineers of the Interior U.S. Army Corps of Engineers

U c-- C_ et v-s-__JL FWS/OBS-82/11.13 TR EL-82-4 October 1983

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic)

SURF CLAM

by

Clemon W. Fay, Richard J. Neves, and Garland B. Pardue Department of Fisheries and Wildlife Sciences Virginia Polytechnic Institute and State University Blacksburg, VA 24061

Project Manager Larry Shanks Project Officer Norman Benson National Coastal Ecosystems Team U.S. Fish and Wildlife Service 1010 Gause Boulevard Slidell, LA 70458

This study was conducted in cooperation with Coastal Ecology Group U.S. Army Corps of Engineers Waterways Experiment Station

Performed for National Coastal Ecosystems Team Division of Biological Services Fish and Wildlife Service U.S. Department of the Interior Washington, DC 20240 CONVERSION FACTORS

Metric to U.S. Customary

Multiply To Obtain millimeters (mm) 0.03937 inches centimeters (cm) 0.3937 inches meters (m) 3.281 feet kilometers (km) 0.6214 miles square meters (M2 ) 10.76 square feet square kilometers (km2) 0.3861 square miles hectares (ha) 2.471 acres liters (1) 0.2642 gallons cubic meters (m3) 35.31 cubic feet cubic meters 0.0008110 acre-feet milligrams (mg) 0.00003527 ounces grams (gm) 0.03527 ounces kilograms (kg) 2.205 pounds metric tons (mt) 2205.0 pounds metric tons (mt) 1.102 short tons kilocalories (kcal) 3.968 BTU

Celsius degrees 1.8(C°) + 32 Fahrenheit degrees

U.S. Customary to Metric inches 25.40 millimeters inches 2.54 centimeters feet (ft) 0.3048 meters fathoms 1.829 meters miles (mi) 1.609 kilometers nautical miles (nmi) 1.852 kilometers square feet (ft 2 ) 0.0929 square meters acres 0.4047 hectares square miles (mi 2 ) 2.590 square kilometers gallons (gal) 3 3.785 liters cubic feet (ft) 0.02831 cubic meters acre-feet 1233.0 cubic meters ounces (oz) 28.35 grams pounds (ib) 0.4536 kilograms short tons (ton) 0.9072 metric tons BTU 0.2520 kilocalories

Fahrenheit degrees 0.5556(F° - 32) Celsius degrees CONTENTS

Pac

CONVERSION TABLE ,.ii...... PREFACE ...... iv ACKNOWLEDGMENTS ...... v

NOMENCLATURE//RANGE ."...... I MORPHOLOGY/IDENTIFICATION AIDS...... 3 REASON FOR INCLUSION IN SERIES ...... 3 LIFE HISTORY...... 3 Reproductive Physiology/Strategy ...... 3 Spawning ...... 3 ...... 3 Larvae ...... 4 Juveniles ...... 4 Adults ...... 5 GROWTH CHARACTERISTICS ...... 6 Growth Rates ...... 6 Length-Weight Relatio is ...... 6 Age-Length/Age-Weight Relationships ...... 7 THE FISHERY ...... 77...... Commercial FI heries.7 Population Dynamics ...... 10 ECOLOGICAL ROLE•...... 11 Food Habits ...... ,...... 11 Feeding Behavior . . 13 Predators ...... 13 Competitors...... 14 ENVIRONMENTAL REQUIREMENTS ...... 14 Temperature ...... 14 Salinity ...... 14 Dissolved Oxygen...... 14 Other Environmental Factors ...... 15 Pollutants ...... 16

LITERATURE CITED ...... 18

iii 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 require- ments 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:

Information Transfer Specialist National Coastal Ecosystems Team U.S. Fish and Wildlife Service NASA-Slidell Computer Complex 1010 Gause Boulevard Slidell, LA 70458

or

U.S. Army Engineer Waterways Experiment Station Attention: WESER Post Office Box 631 Vicksburg, MS 39180

This series should be referenced as follows:

U.S. Fish and Wildlife Service. 1983. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates. U.S. Fish and Wildlife Service, Division of Biological Services, FWS/OBS-82/11. U.S. Army Corps of Engineers, TR EL-82-4.

This profile should be cited as follows:

Fay, C.W., R.J. Neves, and G.B. Pardue. 1983. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid- Atlantic) -- surf clam. U.S. Fish and Wildlife Service, Division of Biological Services, FWS/OBS-82/11.13. U.S. Army Corps of Engineers, TR EL-82-4. 23 pp.

iv ACKNOWLEDGMENTS

We are grateful for the review by Steve Murawski, National Marine Fisheries Service, Woods Hole, Massachusetts.

V Figure 1. Surf clam.

SURF CLAM

NOME NC LATU RE/TAXONOMY/RANGE region). A much broader latitudinal range, from the south- ern Gulf of St. Lawrence to the Scientific name ..... Spisula solidissima northern Gulf of Mexico, was Preferred common name...... Surf given in Merrill and Ropes clam (Figure 1) (1969), Ropes et al. (1969), and Other common names .... Bar clam Ropes (1980). Evidence that the (Canada), hen clam (Maine), sea populations south of Cape Hat- clam (Massachusetts), beach clam, teras are actually a distinct sub- skimmer clam (Ropes 1980) species of S. solidissima, S. s. C lass ...... B ivalvia ravaenelli, is presented in Merrill Order ...... Veneroida and Webster (1964) and Jacobsen Family ...... and Old (1966). Surf are predominantly oceanic, most com- Geographic range: Gulf of Maine south mon in turbulent waters just to Cape Hatteras, North Carolina beyond the breaker zone (Ropes (Wigley and Emery 1968) (see 1980). Encroachment into estua- Figure 2 for the distribution of rine zones is probably limited by the surf clam in the mid-Atlantic salinity requirements.

I N.Y.

&

6- r. -

Z. /

ynr .00 N.J. / / / / I I I PHILADELPHIA I I / /

4

D

I I I I I

I' VA. MILES 0 50 100

0 5o 100

I KILOMETERS

Areas of highest abundance

N'Areas of high abundance

Areas of moderate abundance

I Approximate 75-m (246-ft) contour

HA TTERAS

Figure 2. Mid-Atlantic distribution of the surf clam,,with areas of relative abun- dance indicated.

2 MORPHOLOGY/IDENTIFICATION AIDS and some spawning activity may occur in 1-year-old clams (Ropes 1979). Smallest reported shell length at Shells oval to trigonal, concentri- maturity was 45 mm (1.8 inches) cally striated or ridged, otherwise (Ropes 1980). No observations on with no external sculpture; gape fecundity of surf clams are available. slight when shell closed; ligament spi- suloid; complete complement of lateral Spawning teeth; pallial sinus shallow and not larger than adductor muscle scar Surf clam populations from New (Chamberlin 1954). Detailed family Jersey coastal waters exhibited two and generic morphological characteris- annual spawnings in 1962, 1963, and tics and anatomical drawings are given 1964 (Ropes 1968b). These occurred in Ropes (1980). from mid-July to early August and from mid-October to early November. In 1965, a single spawning period REASON FOR INCLUSION IN SERIES from mid-September to mid-October was observed. The spawning season is probably earlier south of New Jer- The surf clam commercial fishery sey, since juvenile clams have been has grown from a small bait fishery found in North Carolina waters in during the years prior to World War II April, May, and June (Williams and (Ropes et al. 1969) to one contribut- Porter 1971). Little is known con- ing 71.8% of all clam meats used in the cerning the spawning season of surf United States between 1970 and 1974 clam populations north of New York. (Ropes 1982). Per capita consumption of surf clam meat doubled between Within a bed of clams, spawning 1947 and 1974 (Ropes 1982). Within is probably a synchronous, annual the mid-Atlantic region, the surf clam event (Ropes 1968b). Water tempera- is a particularly important commercial ture is an important factor influencing clam species because of its wide dis- initiation and time of spawning (Ropes tribution and abundance in the 1980), and may also influence rate of region, and because most vessels in. gonadal ripening and number of major the fishery are located in New York, spawning periods per year (Ropes New Jersey, Delaware, Maryland, and 1968b). After eggs and sperm are Virginia (Ropes 1982). broadcast, fertilization occurs in the water column above the spawning bed of clams (Murawski and Serchuk 1981; LIFE HISTORY Ropes 1980).

Reproductive Physiology/Strategy

Surf clams are heterosexual Surf clam eggs are spherical and (Ropes 1980), though hermaphroditism average 1.42 mm (0.06 inch) in diame- has been reported (Ropes 1968a). ter across the vitelline membrane; the Male and female surf clams are identi- inner germinal vesicle averages 0.79 cal in external appearance, and histo- mm (0.03 inch) in diameter (Allen logical sectioning and examination of 1953). Several layers lie between the gonads is the only sure way to deter- invisible, outer, jellylike layer and mine surf clam gender (Ropes et al. the germinal vesicle (Ropes 1980). 1969). Male and female surf clams Longo (1973) reviewed the literature reach full sexual' maturity during their on embryogenesis of fertilized ..eurf second year, even though ripe gonads clam eggs.

3 Little is known concerning the Larvae reared at the lower tempera- effects of water temperatures on ture were significantly smaller than development rate of surf clam eggs. larvae reared at 220C (72'F) (Loosa- Fertilized eggs held at an average noff and Davis 1963). water temperature of 21.7°C (71'F) (range 18.30 to 24.9'C or 650 to Detailed descriptions of the ana- I 77'F) in the laboratory completed first tomical development of surf clam lar- cleavage by 70 min after fertilization vae from the trochophore larval stage (Costello et al. 1957). Trochophore through the juvenile stage are pro- larvae began appearing 9 hr after vided by Ropes (1980). A key for fertilization (Costello et al. 1957; identifying larvae of 23 clam species Ropes 1980). Fertilized eggs reached inhabiting the Middle Atlantic Bight the veliger larvae stage in 72 hr. at and suggestions for general taxonomic 140C (57°F), and in 28 hr at 220C separation are given in Chanley and (72'F) (Loosanoff and Davis 1963). Andrews (1971). Additional informa- tion on species separation is available Larvae in Loosanoff and Davis (1963) and Loosanoff et al. (1966). Pyramid-shaped, planktonic trocho- phore larvae began developing from Water currents in areas where swimming gastrulae 9 hr after fertili- planktonic surf clam larvae live are zation at a water temperature of important in determining eventual pat- 21.70C (71'F) (Costello et al. 1957; terns of distribution and settlement Ropes 1980). Veliger larvae (first for developing juveniles (Ropes et al. appearance of bivalved shell) formed 1969; Ropes 1980). Dispersal and by 19 to 20 hr after fertilization, and redistribution of surf clams to other a ciliated velum also appeared at this areas, through swimming and crawling time (Ropes 1980). The velum is used activities and water currents, occur for propulsion of the larvae until the primarily during the larval stages. juvenile or "settlement" phase is Specific information, however, on the reached. One day after fertilization, interaction of water currents and lar- 1 veliger larvae averaged 89 microns (1p) val settlement patterns is unavailable long and 71 I high (Ropes 1980). (Ropes 1980). Other reported values for the size of veliger larvae at 1 day were (length Juveniles by height) 95 p by 80 pA (Sullivan 1948) and 80 p by 65 p (Loosanoff et Juvenile surf clams, with a well- al. 1966). developed foot for burrowing and fully absorbed velum, were present 18 days Pediveliger larvae, a transitional, after fertilization at 21.70C (71*F). "swimming-crawling" larval stage with By 21 days, all clam larvae had meta- development of a foot for burrowing morphosed into juveniles; average size (Carriker 1951), were first observed was 303 p long by 267 p high (Ropes 18 days after fertilization at 21.7°C 1980). Other reported values were (71 0 F); by 21 days, nearly all veliger (length by height) 270 p by 245 p larvae had developed through the (Sullivan 1948) and 263 p by 245 p brief pediveliger stage and metamor- (Loosanoff et al. 1966). The juvenile phosed into juvenile clams (complete stage lasts from first settlement in the absorption of velum, settlement to the substrate until sexual maturity, which substrate, and beginning of sedentary may occur during the second (age 1.) life stage) (Ropes 1980). At 140C or third (age 2÷) summer of life. (57"F) and 220C (72*F), metamorpho- sis to juveniles was first observed The extent of juvenile surf clam after 35 and 19 days, respectively. movement by a locomotion called 4

4 "leaping" (a push with the foot Bight are located from the beach zone against the substrate) was investi- to a depth of 43.9 m (144 ft) off Long gated by Ropes and Merrill (1973). A Island, out to 59.7 m (196 ft) off New young surf clam, disturbed from its Jersey, from 10.1 m to 65.5 m (33 ft burrow by the investigators or a to 215 ft) off the Delmarva Peninsula, predator, usually reburrowed in the and from 8.2 m to 58.8 m (27 ft to same spot. Leaping was infrequent, 193 ft) off Virginia and North Carolina and was usually caused by repeated (Ropes 1979). Inshore distribution of disturbance of the clam in its burrow. surf clams, particularly in estuarine Stimuli reported for leaping in a zones, is probably limited by salinity closely related mactrid, coral- requirements (Ropes 1980) (see lina, were (1) proximity to a preda- ENVIRONMENTAL REQUIREMENTS - - tor, (2) inability to ý burrow in the Salinity section). substrate of settlement, and (3) expo- sure to air (Ansell 1969). Ropes and Adult surf clams rarely voluntar- Merrill (1973) concluded that surf clam ily vacate their burrows, and under leaping was exceptional and infre- natural stimuli alone, may live their quent, and probably insignificant in entire lives in a single burrow. determining their overall settlement Studies by Armstrong (1965), Ropes and distribution patterns. Voluntary and -Merrill (1970), and Ropes and leaping (i.e., with no disturbance) Merrill (1973) reported little or no was never observed. voluntary movement of marked clams under natural conditions. Oceanic Adults storms and water currents generated over the floor may displace surf I Adult surf clams spend most of clams a considerable distance (Yancey their lives burrowed in medium to and Welch 1968), but survivors of the coarse sand and gravel substrates. displacement not washed onto the Since siphons are about as long as the beach probably burrow at or near the adult clam, burial depth may be wel'l site where they settle after a storm below the substrate surface (Ropes (Ropes and Merrill 1973). 1980). Papillae fringing the siphonal openings (Morse 1919) may aid in pre- Determinations of surf clam lon- venting sand grains from being drawn gevity have been made from individual into the during respiration and specimens. Three records of the old- feeding (Ropes and Merrill 1973). est surf clams are 17-year-old speci- Abundance of adults in suitable sub- mens averaging 163 mm (6.41 inches) strates ranges from loose, fairly long (Westman and Bidwell 1946), evenly distributed aggregations (Olsen 20-year-old specimens averaging 147 1970) to localized or patchy, dense mm (5.79 inches) (Loesch and Ropes beds, occasionally with individuals 1977), and 25-year-old specimens close enough in the substrate for averaging 164 mm (6.46 inches) (Jones shells to touch (Wilbur 1964; Flowers et al. 1978). The greatest shell 1973; Ropes 1980). length ever reported for surf clams was a 226-mm (8.9-inch) specimen col- Surf clams were a dominant spe- lected offshore of Point Pleasant, New cies collected in surveys of inshore Jersey, at a depth of 21.3 m (70 ft). benthic fauna from southwestern Long This individual was in a commercial Island, New York (Steimle and Stone sample of 10, averaging 193 mm (7.6 1973), and Little Harbor, New inches) and 'ranging from 178 to 226 Jersey (Garlo and Hondo 1973). Most mm (7.0 to 8.9 inches) in length surf clam beds of the Middle Atlantic (Ropes and Ward 1977).

5 GROWTH CHARACTERISTICS the marks were better defined than the external ridges. Since develop- ment of this technique, 'studies by Growth Rates Chang et al. (1976) and Jones et al. (1978) reported age-size relationships In laboratory experiments con- using cut and polished shells (Table ducted at 21.7'C (711F), length-by- 1). These data indicate that surf height measurements of veliger larvae clams sampled from the Ocean City shells at daily ages were I day, 89 V area grew faster and lived longer than by 71 p; 2 days, 89 v by 76 1; 7 those collected from Barnegat Bay and days, 94 p by 79 v; 17 days, 213 11 Point Pleasant areas. But Ropes by 194 p; and 18 days (beginning of (1980) noted that these differences pediveliger stage), 245 -p by 230 p may be a function of depth of the (Ropes 1980). clam bed and its location with respect to shore (i.e., inshore vs. offshore). A unique situation for studying Both Chang et al. (1976) and Jones et surf clam growth occurred in a dis- al. (1978) found that surf clams sam- crete, newly settled clam bed discov- pled from relatively deepwater, off- ered in Chincoteague Inlet, Virginia, shore areas (18.3 to 28.0 m or 60 ft on 1 October 1964 (Ropes et al. to 92 ft deep) grew faster and lived 1969). Age 0÷ clams from this bed longer than those sampled from rela- averaged 21.1 mm (0.8 inch) in shell tively shallow - water, inshore sites length on 28 October 1964. Subse- (11.6 m to 15.0 m or 38 ft to 49 ft). quent samples indicated average shell The influence, however, of exploita- lengths of 42.4 mm (1.7 inches) on 7 tion differences among these popula- July 1965 (age 1+), 68.6 mm (2.7 tions was not considered. inches) on 18 July 1966 (age 2+), and 90.5 mm (3.6 inches) on 7 August The most recently developed 1967 (age 3÷). During the winter of technique for aging surf clams is 1967-68, heavy losses to and thin-sectioning of the chondrophore storm-related mortality reduced this (located in the hinge of the clam) population below levels necessary for (Ropes and O'Brien 1979). Marks on sampling. Projection of the data col- the sectioned chondrophore correspond lected, however, indicated an average to those on the cut and polished shell length of 110 mm (4.3 inches) at shell. This method was apparently age 4+. simpler to use and data on growth easier to collect compared to the Prior to 1975, most determinations valve-cutting technique (Ropes and of age and growth of adult surf clams O'Brien 1979). were made by counting and measuring radii of concentric "rings" or "ridges" Length-Weight Relationships commonly observed on the external surface of shells (e.g., Belding 1910; Shell length (L in mm) to Kerswill 1944; Westman and Bidwell drained-meat weight (W in g) relation- 1946). Growth data from these and ships for surf clam populations of the other studies using the external aging Middle Atlantic Bight were determined method were summarized by Ropes by Murawski and Serchuk (1981), and (1980). Age and growth techniques are presented below for the following were refined by National Marine Fish- areas: (1) southern New England, erie's Service investigators beginning (2) New Jersey, (3) Delmarva Penin- in 1975. Shells cut along a line from sula, (4) North Carolina, and (5) all the umbo to the ventral edge and pol- areas combined. ished revealed distinctive marks related to the external ridges (Ropes (1) In(W) = -7.973 + 2.578 ln(L) 1980). Greater accuracy in measuring (2) In(W) = -9.206 + 2.825 ln(L) age and growth was achieved because (3) ln(W) = -9.106 + 2.767 In(L)

6 Table 1. Surf clam shell length (mm) at age (yr) for three mid-Atlantic locations, determined by the cut-and-polished-shell technique.

Shell length (mm) Age Point Pleasant, Barnegat Bay, Ocean City, (yr) New Jerseya New ,Jerseyb MarylandD

1 38 34 39. 2 62 56 57 3 79 73 94 4 88 88 113 5 94 102 126 6 97 109 136 7 102 --- 143 8 106 --- 148 9 108 --- 152 10 109 --- 156 11 110 --- 159 12 ------161 13 ...... 163

aJones et al. 1978. bChang et al. 1976.

(4) In(W) = -7.058 + 2.303 In(L) where values in parentheses with itexp"t represent the exponent of e, (5) In(W) = -9.194 + 2.805 In(L) the base of natural . Similar relationships for shell length to shell height, shell width, shell weight, total clam weight, and chon- drophore length were given in Chang THE FISHERY et al. (1976).

Age-Length/Age-Weight Relationships Commercial Fisheries

Von-Bertalanffy growth equations Compared to information available for (1) age (t in yr) to shell length on life history and environmental (L in mm), (2) age to total live requirements of surf clams, informa- weight (W in g), and (3) age to tion on fishery operations, stock drained-meat weight (W in g) were assessment, and trend prediction is determined for Middle Atlantic Bight extensive and detailed. Summaries of surf clams (Chang et al. 1976) as fol- fishery operations for 1972 (Ropes et lows: al. 1975a), 1973 (Ropes et al. 1975b), and the period 1965 to 1974 (Ropes (1) L = 174.8(1-e(exp -0.19(t÷0.81))) 1982) are available. Summaries of the (2) W = 762.7(1-e(exp -0.11(t-3.13))) geographical distribution of landings, (3) W = 263.2(1-e(exp -0.14(t-2.05))) relative abundance of exploitable and

7 recruiting stocks, fishery operations 0.122 kg (0.268 Ib) in 1947 to 0.267 through 1982, and predicted trends in kg (0.589 Ib) in 1974. the fishery are available in Ropes (1979) and Murawski and Serchuk Ropes (1982) summarized monthly (1979, 1981, 1982). The reader is landings and trends of the surf clam 4 referred to these seven studies for fishery for five States in the Middle detailed information on surf clam fish- Atlantic Bight, from 1965 to 1974. eries and population dynamics. For Over this 9-year period, landings at the scope and purpose of this profile, New York, Maryland, and Delaware only major aspects and trends of the ports remained relatively stable and fishery are included. low compared to those at New Jersey and Virginia ports. Landings at New Jersey ports declined gradually from Earliest methods of harvesting 1965 to 1970, then more rapidly from. surf clams were by hand-operated 1970 to 1974. Despite the decline, rakes or simply by gathering clams New Jersey ports remained the most from beaches after storms (Parker important for total clam landings 1971). During the 1920's, scraper- through 1972. Landings at Virginia type dredges towed behind power- ports began to increase sharply in boats were used, but were relatively 1970 as fishermen shifted their efforts inefficient and broke many clams.. In southward. By 1974, Virginia land- the mid-1940's, the water-jet dredge ings had surpassed New Jersey land- was ' developed. This innovation ings, and these two States accounted increased fishing efficiency, decreased for more than 80% of all surf clam clam breakage, and was instrumental landings (Ropes 1982). in developing the modern-day surf clam fishery (Ropes 1980). Clam stocks and harvests from New Jersey waters continued to The present surf 'clam fishery decline after 1974, but some signs of uses a "knife-scraper" dredge with a at least temporary rebuilding of fisha- water-jet system mounted ahead of the ble stocks were evident in 1981 trawl scraper. These dredges are larger surveys (Murawski and Serchuk and heavier than those used in the 1981). In contrast to the New Jersey 1940's. The knife may be as wide as fishery, fisheries off Virginia (includ- 3 m (10 ft), and the water-jet hose as ing the Delmarva Peninsula) have large as 20 cm (7.8 inches) in diame- increased in importance to the overall ter. Special vessel construction is fishery. Commercial fisheries appar- now necessary to tow these dredges ently continue to shift the concentra- effectively. The addition of stern tion of effort southward, since north- ramps and conveyor systems to clam ern stocks remain at relatively low fishing boats constructed or converted levels (Murawski and Serchuk 1981). after 1970 has further increased fish- ing efficiency (Ropes 1980). Table 2 summarizes total U. S. landings of surf clams'between 1965 and 1981. Percentage of the total The commercial fishery for surf catch outside State territorial waters clams has developed from one during (greater than 4.8 km or 3 mi off- World War II, when surf clams sup- shore) is also given in Table 2 (data plied 3.2% of the U. S. landings of from Murawski and Serchuk 1982, and clam meats, to an extensive fishery by National Marine Fisheries Service the late 1950's. Between 1970 and 1978-1982). Total U. S. landings in 1974, surf clams provided 71.8' of all 1974 and 1975 were 96.1 million lb clam meats used in the United States. (43.6 thousand metric tons (mt)) and Per capita consumption of surf clams 87.0 million lb (39.5 thousand mt) of in the United States has doubled from shucked meats, respectively. In

8 Table 2. Total U.S. commercial landings of surf clams (in thousands of lb of meats), U.S. commercial landings from the Fishery Conservation Zone (4.8 to 321.9 km or 3 to 200 mi offshore), and the percentage of the total landings taken in the Fishery Con- servation Zone.

/ Total Landings outside Percent of landingsa Year landings 3 mi offshore outside 3 mi (thousands of lb) (thousands of lb) 1965 44,088 33,000 74.9 1966 45,113 32,400 71.8 1967 45,054 24,700 54.8 1968 40,552 20,000 49.3 1969 49,575 15,900 32.1 1970 67,318 14,100 20.9 1971 52,535 50,053 95.3 1972 63,371 55,272 87.1 1973 82,370 72,579 88.1 1974 96,110 74,430 77.4 1975 86,956 44,270 50.9 1976 49,133 42,558 86.6 1977 51,036 42,968 84.2 1978 39,237 31,393 80.0 1979 34,912 29,070 83.3 1980 37,737 34,718 92.0 1981 46,100 37,340 81.0 1982 2 7 , 6 3 5b aproration for 1972-81 based on data presented in Fisheries of the.United States (National Marine Fisheries Service 1978-1982). Earlier data from Murawski and bSerchuk (1982). Only preliminary data available for 1982.

1976, total landings dropped to 49.1 lb (17.1 thousand mt) and 46.1 million million lb (22.3 thousand mt). The lb (20.9 thousand mt), respectively. major reason for the large decline between 1975 and 1976 was the col- For landings in 1981, 58% came lapse of the New Jersey fishery, due from Delmarva Peninsula fishing areas, to large areas of ocean-bottom water while 41% came from northern New with low levels (<2.0 ppm) of dis- Jersey areas. Only 1% of the catch solved oxygen during the spring and was taken from southern New Jersey, summer of 1976 (see ENVIRONMENTAL which in the 1960's and early 1970's REQUIREMENTS -- Dissolved Oxygen had been one of the more important section). Total landings dropped even clam fishing grounds (Murawski and further by 1979, to 34.9 million lb Serchuk 1981). Part of the apparent (15.9 thousand mt), but increased rebound of the sunf clam fishery in again in 1980 and 1981 to 37.7 million 1980 and 1981 was due to improved

9 resource conditions in the northern the 1976 cohort still remains below New Jersey areas. exploitable size (14 cm or 5.5 inches), but is predicted to enter the fishery Except for 1975, greater than 75o in substantial numbers by mid-1983. of all surf clam landings between 1971 Harvestable biomass in southern New and 1981 came from areas greater than Jersey waters has also increased from 4.8 km (3 mi) offshore (Table 2). In low levels in the late 1970's, but is 1980 and 1981, 92% and 81%, respec- still well below that which was availa- tively, of the total landings came from ble to fishermen in the late 1960's the U. S. Fishery Conservation Zone (Murawski and Serchuk 1981). The (4.8 to 321.9 km or 3 to 200 mi off- Delmarva Peninsula has maintained shore). These offshore areas are fairly stable levels of harvestable bio- apparently increasing in importance, mass since it became an important as easier-to-fish but overexploited fishing ground in the mid-1970's. inshore populations remain depleted However, most of the 1981 landings (Murawski and Serchuk 1981). prior to July 1981 (adoption of the size limit) came from the relatively After passage of the Fishery strong 1977 year class in the Delmarva Conservation and Management Act of area, and adoption of the minimum 1976, a Fishery Management Plan size limit curtailed full exploitation of (FMP) was developed for surf clam this year class until at least 1984 stocks in the U. S. Fishery Conser- (Murawski and Serchuk 1981). vation Zone. At the time this FMP was developed, surf clam stocks were Population Dynamics at a relatively low level compared to historical stocks. Intensive fishing Sex ratios. A 4-year study of the during the 1960's and early 1970's and reproductive cycle of surf clams off the oxygen depletion dieoff in New the New Jersey coast, between 1962 Jersey waters in 1976 reduced exploit- and 1965, indicated that sex ratios in able surf clam stocks. To achieve the clam beds did not deviate significantly catch goals in the FMP, various regu- from a 1:1 ratio (Ropes 1968b). Data latory mechanisms have been imple- from National Marine Fisheries Service mented, including annual and quar- (NMFS) surveys during 1965 and mis- terly landings quotas, weekly effort cellaneous sources also indicated no restrictions, a moratorium on new significant deviation from a 1:1 sex vessel construction, closure of specific ratio in the populations sampled areas to protect young clams (future (Ropes 1980). recruitment), and most recently (26 July 1981) a minimum clam size of 14 Age composition. According to all cm (5.5 inches) (Murawski and Ser- of the clam age data from Ropes chuk 1981). Since its adoption, the (1980), the age classes (determined minimum size limit has resulted in the by both external and shell-sectioning further decline of catch per unit aging techniques) present in samples effort, thus indicating the importance from various mid-Atlantic areas were of 10- to 13-cm (3.9- to 5.1-inch) as follows: offshore Virginia, 1 to 19 clams to the fishery prior to size reg- (Loesch and Ropes 1977); inshore ulation (Murawski and Serchuk 1981). Chincoteague Inlet, Virginia, 1 to 3 (Ropes et al. 1969); offshore Ocean The most recent assessments of City, Maryland, 1 to 13 (Chang et al. the abundances of fishable and 1976); inshore Barnegat Bay, New recruiting surf clam stocks indicate Jersey, 1 to 6 (Chang et al. 1976); that the relatively strong 1976 year inshore Point Pleasant, New Jersey, 1 class has helped restore northern New to 11 (Jones et al. 1978); offshore Jersey fishing grounds. The bulk of Point Pleasant, New Jersey, 1 to 25

I

10 (Jones et al. 1978); offshore central models, natural mortality rate (M) was New Jersey, 1 to 12 (Ropes 1980); assumed equal to 0.2 (estimated with and offshore Long Island, New York, catch curves from diving expeditions), 1 to 17 (Westman and Bidwell 1946). and recruitment was assumed constant These age class data support the at 500,000 age 1 clams per year to an hypothesis that individuals from off- initial population size of 2.8 million shore, deepwater clam beds live clams. Values for variables in the longer than those from inshore, shal- three yield models were (1) age at low water beds. Differences in age first capture 5 years (approximately class structure among populations, 8.0 cm or 3.1 inches) and F=0.5, however, may be because of varying (2) age at first capture 3 years degrees of exploitation in inshore and (approximately 4.0 cm or.1 6 inches) and offshore beds. F=0.5, and (3) age at first capture 3 years and F=0.25 (Caddy and Billard Recruitment and production. Rel- 1976). ative abundance (mean number per tow) of recruiting surf clams (less For, all three models, catch rates than 14.0 cm or 5.5 inches) in declined steadily from the first year National Marine Fisheries Service bot- of fishing through the eighth year. tom trawl surveys from 1965 to 1978 is Long-term yield per recruit was 40% summarized in Table 3 (data from higher for model (1) compared to Murawski and Serchuk 1982). Excep- model (2). Model (1) approximated an tionally high abundances in surveys optimum sustained yield per recruit. beginning in December 1978 off north- Initial catch under model (2) was half ern New Jersey and Delmarva Penin- that of the other models, but long- sula indicated relatively strong year term catch under model (2) was inter- classes in 1976 and 1977 in those mediate to models (1) and (3). areas. Young clams from the 1976 and Although model (1) appeared to be 1977 year classes were predicted to near optimum for long-term sustained enter the fishery by 1982 (prior to yield, model (3) was predicted to have establishment of a minimum size limit) the highest catch per unit effort (kg (Murawski and Serchuk 1979). How- per diver hour); and model (1) would ever, with the adoption of the 14-cm require twice the fishing effort of (5.5-inch) minimum size limit in July model (3) to achieve the long-term 1981, these year classes will probably predicted y ield (Caddy and Billard not be recruited to the fishery until 1976). Caddy and Billard (1976) also 1983 or 1984' (Murawski and Serchuk noted that fishing mortality rates 1981). higher than 0.5 or age of first cap- ture greater than 5 years significantly In three unexploited surf clam decreased yield per recruit compared beds in the Gulf of St. Lawrence, off to the three models tested (this was Buctouche, New Brunswick, density of apparently determined in preliminary surf clams averaged 1.06/mi model testing). (0.10/ft 2 ) and ranged from 0.68 to 1.25/M2 (0.06 to 0.12/ft 2 ). Total estimated standing crop in these three ECOLOGICAL ROLE beds, which collectively covered 2.6 km 2 (1.0 mi 2), was 2.8 million clams (Caddy and Billard 1976). Three Food Habits models for predicting yield based on varying fishing mortality rate (F) 'and In laboratory- reared surf clam age of first capture were tested by larvae, yolk material was fully using data from these unexploited absorbed and algal cells began beds. To develop and test these appearing in some stomachs at 1 day

11, Table 3. Relative abundance (mean number per standardized 5-min tow) of recruit- ing (less than 14.0 cm or 5.5 inches) surf clams from National Marine Fisheries Service surveys, 1965-82, in the Fishery Conservation Zone offshore of northern New Jersey, southern New Jersey, Delmarva Peninsula, and Virginia-North Carolina (data from Murawski and Serchuk 1982).

Northern Southern Delmarva Virginia- Cruise period New Jersey New Jersey Peninsula N. Carolina

May 1965 15.4 78.1 15.8 2.9 Oct 1965 6.2 33.3 10.8 11.8a Aug 1966 5.4 14.6 10.7 16 . 3a Jun 1969 3.9 5.5 8.0 78.7 Aug 1970 4.8 2.7 4.7 0. 7 a Jun 1974 2.7 2.2 6.7 12.7 Apr 1976 2.4 0.6 7.3 1.1 Jan 1977 1.4 1.2 2.7 Jan 1978 1.5 3.9 4.9 1.1 Dec 1978 43.9 4.5 616.4 86.1a Jan 1980 27.5 2.5 58.1 Aug 1980 .50.7 2.9 39.4 31.1 0.6 156.9 18.0a Aug 1981 1.2a Aug 1982 101.5 3.6 102.5

aOnly a small portion of the total Virginia-North Carolina offshore area was surveyed.

of age (veliger larvae) (Ropes 1980). Tintinnus spp. were identified from Larval surf clams fed on algal cells the contents (Leidy 1878). Difficul- throughout the remainder of the stage ties in identification were caused by (Ropes 1980). Loosanoff and Davis change in diatom structure after entry (1950, 1963) successfully reared larval into the surf clam's digestive tract. surf clams on mixed plankton cultures and discussed conditions necessary for Stephens and Schinske (1961) raising larval surf clams in relation to observed that the amino acids glycine, food. Laster and Strittmater (1968) glutamic acid, tyrosine, methionine, noted that maltase activity in develop- phenylalinine, and arginine were suc- ing larval surf clams increased tenfold cessfully removed from food items in the early veliger stage, coincidental ingested by surf clams, and appeared with development of the esophagus, to be of nutritional value. Food con- stomach, intestine, and digestive sumed and assimilated by surf clams gland. probably depends on geographic loca- tion and depth of the bed, seasonal Stomachs of adult surf clams from variation in availability of food items New Jersey coastal waters contained a and feeding activity, and annual or variety of diatom genera and species, long-term fluctuations in diversity and but only Amphipora constricta and abundance of food organisms. I

12 Feeding Behavior waters is available (e.g., Hunt 1925; Birkett and Wood 1959; Thorson 1966; Muus 1966, 1973; Christensen 1970; Like many bivalves, surf clams Masse 1975), but its relevance and are plan ktivorous, siphon feeders. applicability to Atlantic coast surf Feeding activity, of surf clams is inti- clam populations are unknown. mately associated with the overall pro- cess of siphoning water for respiration The most important predators on and excretion (Ropes 1980). Feeding adult surf clams are two moon surf clams burrow deep enough in the species, Lunatia heros and Polinices substrate so that the end of the duplicatus. A characteristic counter- incurrent siphon barely protrudes sunk hole drilled by the snail's above the bottom (Ropes and Merrill is usually located near the hinge or 1976). Some sand grains and other umbo of the shell. Low temperatures unwanted material may be ingested and salinities apparently reduce pre- under these circumstances, but the dation rates of these (Hanks action of papillae fringing the siphon 1952). In laboratory experiments P. may reduce such occurrences (Morse duplicatus ceased feeding at 5 -C 1919; Jacobsen 1972). Surf clams in (41'F) or lower and 6 ppt salinity, while L. heros the breaker zones of coastal oceanic reduced feeding at 20 C habitats close their siphons when (35.6"P) or lower and ceased feeding breaking waves with suspended sand below 10 ppt salinity. Lunatia heros pass by, reopening the siphon quickly may be a size-selective predator on after the wave passes (Jacobsen surf clams, since Franz (1977) found 1972). Food particles trapped on the that most surf clams selected by snails mucus-coated inner siphonal surfaces off Long Island were less than 80 mm move unidirectionally with the mucus (3.1 inches) in shell length. This toward the gut of the clam (Kellog selection, however, may also be 1915). Morphology and responses of related to seasonal or geographic the incurrent siphonal valve and availability of clam size classes to adductor muscles of surf clams, used predators. to clean debris from the siphonal cav- ity, were described by Prior (1974). Another invertebrate predator of The crystalline style in the digestive the surf clam is the boring snail, tract stirs the stomach contents and Urosalpinx cinerea. In laboratory aids in producing and . excreting experiments this snail was unable to enzymes for digestion (Ropes 1980). bore successfully in running seawater, Studies have been conducted on the but was much more effective at boring enzymes and enzymatic processes in surf clam shells in standing seawater the surf clam gut (Lavine 1946; Patton (Pratt 1974). and Quinn 1973; Shallenberger et al. 1974, 1975; Lindley and Shallenberger Predatory fish reported to con- 1976, 1977) and on the neurophysio- sume surf clams are haddock (Melano- logical mechanisms of qut movements grammus aeglefinus) (Clapp 1912; (Nystrom 1976; Smucker and Nystrom Clarke 1954) and cod (Gadus morhua) 1970, 1972). (Bigelow and Schroeder 1953; Clarke 1954). Much of this apparent preda- Predators tion may result from scavenging on the soft bodies of fractured surf clam Little is known concerning the shells which result from major oceanic predators of planktonic surf clam lar- storms. Recreational cod and haddock vae or newly settled juveniles. Some fishermen believe that surf clam soft information on predators of other bodies are one of the best baits for young mactrid clams in European several days after a major oceanic

13 storm, but are only fair baits at other temperatures of 300C (86"F) or higher times. (Loosanoff and Davis 1963). Adult surf clams were unable to establish Competitors pedal anchorage at water temperatures greater than 30'C (86°F) (Savage I Little is known concerning com- 1976). Lethally low water tempera- petitive interactions between surf tures for adult surf clams are proba- clams and other benthic organisms. If bly never reached in their oceanic competition occurs, it probably habitat, but low air temperatures (less involves availability of, space at the than 00C or 32 0 F) may freeze exposed appropriate depth in the substrate gill tissue- in live clams temporarily and, availability of usable food organ- washed up onto the beach during isms in the water column just above storms (Ropes 1980). the seabed (Ropes 1980). In laboratory experiments, the Some evidence exists for intra- burrowing rate of surf clams increased specific competition in dense, inshore as water temperature increased to surf clam beds, including roughened 20'C (68°F), but decreased above this shell surfaces and edges, older shell temperature (Savage 1976). Some deposits raised one on top of another clams failed to begin digging activities like shingles, and blunted posterior at water temperatures below 20C ends of shells (Ropes 1980). These (36'F), and others began digging but features are generally unique to dense could not accomplish complete burial at populations and, may indicate disrup- that temperature. Temperature tion in growth patterns through some shocks induced by a 140C (25OF) competition among clams 'for space or increase in water temperature, with a food (Ropes 1980).. In laboratory starting temperature of 4'C (39'F), experiments, localized, physical stimu- did not significantly affect burrowing. lation of the edge of some mol- A temperature increase of 220C (40"F) lusks produced large areas of shell produced gaping, lethargy, and even- regeneration, indicating that proximity tually death (Ropes 1980). Water 4 of individual clams in dense beds may temperature is also important for initi- account for the irregularities in shell ation and rate of gonadal development growth observed in such beds (Wilbur (Loosanoff and Davis 1963), and for 1964). initiation and timing of spawning (Ropes 1968b).

ENVIRONMENTAL REQUIREMENTS Salinity

Minimum salinities for larval and Temperature adult surf clam survival were 16 ppt and 12.5 ppt, respectively (Castagna Surf clam larvae tolerated a water and Chanley 1973). Adult surf clams temperature range from 14 0 C to 30'C tolerated salinities from 14 ppt to 52 (57'F to 86'F) (Loosanoff and Davis ppt (concentrated seawater) (Theede 1963). Optimum temperature for lar- 1965). Encroachment of surf clams val development was 22*C (72*F) into estuarine areas is probably lim- (Loosanoff and Davis 1963). Juvenile ited by salinity (Ropes 1980). surf clams survived higher tempera- tures than adults, but became inactive Dissolved Oxygen at 4'C (39'F) or lower (Saila and Pratt 1973). Survival of spawning Several instances of severe adults and their fertilized eggs was depletion of dissolved oxygen in the significantly affected at water bottom waters of the ocean (equivalent I

14 to the hypolimnion in freshwater), sealing off organically rich, oxygen- along the, New Jersey and Long Island demanding (vater (from dead and coasts, have produced surf clam mor- dying dinoflagellates) early in the talities. A major event of this type spring; (3) additional organic loading occurred in the spring and summer of from human waste dump sites off New 1976. Anoxic water developed over Jersey and Long Island; (4) limited clam beds between Cape May, New water mass movement for an extended Jersey, and Long Island's south period (4-6 weeks), due to a persist- shore, out to a depth of 75 m (246 ent southerly flow of air; and ft), because of the combined effects (5) abnormally low cyclonic storm activ- of meteorological and hydrographic ity over the same 4- to 6-week period. conditions, organic loading from Any one of these events probably human waste dump sites, and an would not have caused oxygen deple- unusually large bloom and die-off of tion to the extent observed, but the dinoflagellate Ceratium tripos together they devastated New Jersey (Steimle and Sindermann 1978). The and Long Island surf clam populations kill area was estimated at 6,750 km2 (Steimle and Sindermann 1978). (2,605 mi 2 ), and the loss of meat weights was estimated at 147 thousand Little specific information is mt (162 thousand tons), representing available concerning the long-term or 62% of the New Jersey surf clam short-term dissolved oxygen require- resource (Steimle and Sindermann ments of surf clams. However, since 1978; Ropes 1980). Dissolved oxygen part of the estimated kill zone in 1976 isopleths measured during the kill was between the 1.0-ppm and 2.0-ppm period indicated an area of approxi- dissolved oxygen isopleths, a lower mately 278 km 2 (107 mi 2 ) (approxi- lethal limit of 2.0 ppm can be assumed mately 12.8 km or 8 mi southeast of until more detailed information on Barnegat Inlet, New Jersey) where oxygen requirements is collected. hypolimnetic waters contained no Prior to 1976, other less extensive measurable dissolved oxygen. A total oxygen depletion events and associ- area of approximately 9,722 km 2 ated surf clam mortalities had been (3,752 mi 2 ) contained 1.0 ppm dis- observed (Ogren 1969; Ogren and solved oxygen or less in the hypolim- Chess 1969; Young 1973). In addition nion. Nearly the entire area along to causing mortality, low dissolved the New Jersey coast, from the shore- oxygen concentrations (values not ward limit of the hypolimnion to a given) were reported to depress bur- depth of 75 m (246 ft), contained 2.0 rowing activities of surf clams (Savage ppm or less dissolved oxygen (Steimle 1976) and may be a stimulus for surf and Sindermann 1978). Other impor- clams to vacate their burrows (Ropes tant commercial , such as 1980). ocean quahogs (Artica islandica) and sea () Other Environmental Factors were also affected, as well as some finfish populations. Though specific studies are lack- ing, water currents are thought to be All available evidence indicated important in influencing distribution of that the specific events that caused planktonic, larval stages of the surf development of anoxic bottom waters clam, and in the development of new in 1976 were (1) an unusually warm surf clam beds (Ropes 1980). Major winter, with highest river runoff in water current patterns over weeks or February rather than April, thus months may also influence availability allowing early development of dense of dissolved oxygen in the oceanic dinoflagellate populations; (2) earlier hypolimnion, and in combination with than normal thermal stratification, other abiotic and biotic events, may

15 influence surf clam mortality rates conditions in and around shellfish (see ENVIRONMENTAL REQUIREMENTS beds. Positive fecal coliform counts -- Dissolved Oxygen section). were reported in 70% of surf clam samples taken offshore of Delaware• Hydraulic water-jet dredges used Bay in 1966 and 1967 (Buelow 1968). by commercial fishermen to harvest Areas in the New York Bight contami- clams apparently do not stimulate nated with human fecal coliforms were uncaptured individuals to actively contiguous with sewage and sludge leave the area, since these fishermen disposal sites, and extended north- may repeatedly dredge the same areas eastward 11 km (6.8 mi) and south- for weeks or months (hotspots), and ward 37 km (23.0 mi) from Hudson continually take clams in commercially River Estuary dumping sites (Babin- usable numbers (Ropes and Merrill chak et al. 1977). Pearce (1972) con- 1973). These same water-jet dredges, cluded that "normal benthic communi- however, may affect survival of ties" in the New York Bight had been uncaptured clams by increasing expo- significantly altered by solid waste sure to snail predators. Also, uncap- disposal in the bight. In most areas tured surf clams are prone to injury of solid waste dumping, surf clams from the water-jets because their were a dominant bivalve in an other- shells gape slightly at the siphon end. wise low-diversity, high-dominance The water-jets force the shells open, assemblage (Pearce 1972). This gen- expose the soft bodies to predation, eral degradation of community diver- and disrupt normal respiration, feed- sity was also noted by O'Connor ing, and excretion (Ropes 1980). (1976). Commercial size surf clams Surf clams in general are less hardy were rare in a 1,550-km2 (598-mi2 ) than hard clams (Mercenaria merce- area surrounding dump sites off New naria), which can close their shells Jersey, even though surf clams were tightly (Ropes 1980). MacKenzie common outside the immediate areas of (1982) concluded that hydraulic dumping. dredges used in commercial fisheries for ocean quahogs (a closely related The continual leaching of contam- mactrid) off New Jersey did not sig- inants from oceanic dump sites intol nificantly affect abundance of inverte- the water and sediments and the brates in areas of dredging. uptake by sedentary oceanic fauna such as the surf clam have forced Pollutants closure of various important clam- harvesting areas of the Middle Atlantic Two major classes of pollutants Bight over the past two decades. have been documented to affect surf Most areas closed during this period clam populations or exploitation of were between Delaware Bay and the those populations: (1) human refuse, southeast end of Long Island (Verber sewage, and sludge (oceanic dump 1976; Babinchak et al. 1977; Ritchie sites), and (2) metals. 1977). An approximate total area of 1,580 km2 (610 mi 2 ) of the Middle Zoellner (1977) reviewed water Atlantic Bight was and remains closed quality problems related to molluskan because of contaminants in clam bodies shellfish and the effectiveness of cur- from dump sites (Ropes 1980). A rent discharge control laws. Although further effect of dump sites is the natural phenomena,' dredging, and contribution to biological oxygen chemical contamination were all noted demand in the oceanic bottom waters as having significant impacts on (see ENVIRONMENTAL REQUIRE- shellfish populations, he considered MENTS -- Dissolved Oxygen section), domestic waste discharge to have the thereby increasing surf clam mortali- greatest negative impact on sanitary ties due to natural periodic depletions 4

16 of oxygen in bottom waters of the near sewage' and acid waste dump ocean (Steimle and Sindermann 1978). sites offshore of Delaware Bay. Recently, the Environmental Protection Studies have delineated lethal Agency estimated that an area of concentrations of certain heavy metals 3,600 km2 (1,389 mi 2 ) off Maryland and determined sublethal concentra- and Delaware had several potentially tions contained in natural populations toxic metals in sediments and organ- of surf clams. In laboratory studies, isms. Though surf clams were not 96-hr LC5 o values for silver were analyzed, two closely related species (1)between 50 ppb and 100 ppb for juve- from the area, ocean quahogs and sea niles, and (2) greater than 100 ppb scallops, contained elevated concen- for adults (Thurberg et al. 1975). trations of vanadium in their body Sublethal effects (observed for larvae tissues (Lear and Pesch 1975). at 50 ppb and juveniles at 10 ppb) appeared as increases in metabolic oxygen requirement. and rhythmic Relatively high concentrations of valve movement, both indicators of cadmium, copper, nickel, vanadium, higher respiration and filtration rates. chromium, and zinc were found in Silver accumulated rapidly in gills and surf clams from Delaware Bay (Rey- other body tissues of test specimens, nolds 1979), though sample sizes were and silver concentrations in gill tis- too small to test statistically. Mean sues were four times as high as con- arsenic levels in Middle Atlantic Bight centrations in other body tissues surf clams ranged from 1.46 ppm to (Thurberg et al. 1975). 2.66 ppm, a range exceeding allowable levels (1.14 ppm) recommended by the Elevated concentrations of iron Australian National Health and Medical and copper (Lear et al. 1973) and Research Council (Wenzloff et al. chromium and nickel (Buelow 1968) 1979) (no levels recommended by were found in surf clams collected Environmental Protection Agency).

17 LITERATURE CITED Allen, R. D. 1953. Fertilization and estuaries. Ecol. Monogr. 21: 4 artificial activation in the egg of 19-38. the surf clam. Biol. Bull. (Woods Hole) 105: 213-239. Castagna, M., and P. Chanley. 1973. Salinity tolerance of some marine Ansell, A. D. 1969. Leaping move- bivalves from inshore and estua- ments in the . Proc. rine environments in Virginia on Malacol. Soc. Lond. 38: 387-399. the western mid-Atlantic coast. Malacologia 12: 47-96. Armstrong, L. R. 1965. Burrowing limitations in Pelecypoda. Veliger Chamberlin, J. L. 1954. Studies in 7(3): 195-200. the Mactrinae. Ph.D. Thesis. Harvard University, Cambridge, Babinchak, J. A., J. T. Graikoski, Mass. 46 pp. S. Dudley, and M. F. Nitkowski. 1977. Distribution of faecal coli- Chang, S., J. W. Ropes, and A. S. forms in bottom sediments from Merrill. 1976. An evaluation of the New York Bight. Mar. Pol- the surf clam population in the lut. Bull. 8: 150-153. Middle Atlantic Bight. U. S. Nati. Mar. Fish. Serv., North- Belding, D. L. 1910. The growth and east Fisheries Center, Sandy habits of the sea clam (Mactra Hook, N. J., Lab. Ref. No. solidissima). Rep.. Comm. Fish. 76-1. 43 pp. Game Mass., Publ. Doc. 25: 26-41. Chanley, P., and J. D. Andrews. 1971. Aids for identification of l Bigelow, H. B., and W. C. Schroe- bivalve larvae of Virginia. Mala-4 der. 1953. Fishes of the Gulf of cologia 11: 45-119. Maine. U. S. Fish Wildl. Serv. Fish. Bull. 74. 577 pp. Christensen, A. M. 1970. Feeding biology of the sea star, Astro- Birkett, L., and R. J. Wood. 1959. pecten irregularis. Ophelia 8: Shell and siphon regeneration in 1-134. . Nature 184: 1075-1076. Clapp, W. F. 1912. Collecting from haddock on the Georges Banks. Buelow, R. W. 1968. Ocean disposal of Nautilis 25: 104-106. waste material. Trans. Ocean Sci. Engin. of the Atlantic Shelf. Clarke, A. H., Jr. 1954. Shell bear- NatI. Symp., Philadelphia, Pa., ing mollusks off Cape Ann, Mas- 1978: 311-337. sachusetts. Nautilis 67: 112-120.

Caddy, J. F., and A. R. Billard. Costello, D. R., M. E. Davidson, A. 1976. A first estimate of produc- Eggers, M. H. Fox, and C. Hen- tion from an unexploited popula- ley. 1957. Methods of obtaining tion of the bar clam, Spisula soli- and handling marine eggs and dissima. Can. Fish. Mar. Serv. pp. embryos. Mar. Biol. Lab., Tech. Rep. 648. 13 Woods Hole, Mass. 247 pp.

Carriker, M. R. 1951. Ecological Flowers, J. M. 1973. Pattern of dis- observations on the distribution tribution of the surf clam in the of larvae in New Jersey Point Judith, Rhode Island 4 1

18 harbor of refuge. Proc. Nati. Board Can., Prog. Rep. AtI. Shellfish. Assoc. 63: 107-112. Coast Stn. 35: 18-20.

Franz, D. R. 1977. Size and age- Laster, L., and P. Strittmater. 1968. specific predation by Lunatia Maltase activity in developing heros on the surf clam Spisula embryos and adult tissues of the solidissima off western Long surf clam. Biol. Bull. (Woods Island, New York. Veliger 20: Hole) 134: 427-428. 144-150. Lavine, T. F. 1946. A study of the Garlo, E., and J. J. Hondo. 1973. enzymatic and other properties of Benthic invertebrates. Ichthyol. the crystalline style of clams: Assoc., Inc. Prog. Rep. January- evidence for the presence of a December 1973, Vol. 2. 527 pp. cellulase. J. Cell. Comp. Phys- iol. 28: 183-195. Hanks, J. E. 1952. The effects of changes in water temperature and Lear, D. W., and G. G. Pesch. 1975. salinity on the feeding habits of Effects of ocean disposal activi- the boring snails, Polinices heros ties on mid-Continental Shelf and Polinices duplicata. Rep. environment off Delaware and Invest. Shellfish. Mass., Com- Maryland. Environmental Protec- monwealth of Mass., Dep. Con- tion Agency Rep. EPA serv., Div. Mar. Fish. 5: 903/9-75-015. 29 pp. 33-37. Lear, D. W., S. K. Smith, and M. L. O'Malley. 1973. Environmental Hunt, 0. D. 1925. The food of bottom survey of two interim dumpsites fauna of the Plymouth fishing of the Middle Atlantic Bight. grounds. J. Mar. Biol. Assoc. Environmental Protection Agency U.K. 13: 560-599. Cruise Rep., November 1973. 141 pp. Jacobsen, M. K. 1972. Observations on the siphonal behavior of Leidy, J. 1878. Remarks on Mactra. young surf clams, Spisula soli- Proc. Acad. Nat. Sci. Phila. dissima. Nautilis 86: 25-26. 1878: 332-333.

Jacobsen, M. K., and W. E. Old, Jr. Lindley, M. G., and R. S. Shallen- 1966. On the identity of Spisula berger. 1976. Purification and similis. Am. Malacol. Union Inc. characterization of a mollusc Annu. Rep. 1966: 30-31. B-D-(1->3) - glucan hydrolase. Food Chem. 1: 149-159. Jones, D. S., I. Thompson, and W. Ambrose. 1978. Age and growth Lindley, M. G., and R. S. Shallen- rate determinations for the Atlan- berger. 1977. Enzyme hydrolysis tic surf clam, based on internal of malt glucans using a mollusc growth lines in shell cross- carbohydrase preparation. Food sections. Mar. Biol. (Berl.) 47: Chem. 2: 1-6. 63-70. Loesch, J. G., and J. W. Ropes. Kellog, J. L. 1915. Ciliary mechanism 1977. Assessment of surf clam of lamellibranchs. J. Morphol. stocks in nearshore waters along 26: 625-701. the Delmarva Peninsula and in the fishery south of Cape Henry. Kerswill, C. J. 1944. The growth rate Proc. Nati. Shellfish. Assoc. 67: of the bar clam. Fish. Res. 29-34.

19 Longo, F. J. 1973. Fertilization: a England. Proc. Boston Soc. Nat. comparative ultrastructural Hist. 35: 139-196. review. Biol. Reprod. 9: 149-215. Murawski, S. A., and F. M. Serchuk 1979. An assessment of offshore 4 Loosanoff, V. L., and H. C. Davis. surf clam populations off the 1950. Conditioning V. mercenaria Middle Atlantic coast of the for spawning and breeding, in United States. U.S. Nati. Mar. Fish. winter and rearing its larvae in Serv., Northeast Fisheries Cen- the laboratory. Biol. Bull. ter, Woods Hole, Lab. Ref. No. (Woods Hole) 98: 60-65. 79-13. 15 pp.

Loosanoff, V. L., and H. C. Davis. Murawski, S. A., and F. M. Serchuk. 1963. Rearing of bivalve mol- 1981. Assessment and current lusks. Pages 130-136 in F. S. status of offshore surf clam pop- Russel, ed. Advances in marine ulations off the Middle Atlantic biology, Vol. 1. Academic Press, coast of the United States. U.S. New York. 410 pp. Natl. Mar. Fish. Serv., Northeast Fisheries Center, Woods Hole, Loosanoff, V. L., H. C. Davis, and Lab. Ref. No. 81-33. 20 pp. P. Chanley. 1966. Dimensions and shapes of larvae of some marine Murawski, S. A., and F. M. Serchuk. bivalve mollusks. Malacologia 4: 1982. Assessment and current 351-435. status of offshore surf clam pop- ulations off the Middle Atlantic MacKenzie, C. L., Jr. 1982. Compat- coast of the United States. U.S. ability of invertebrate populations Nati. Mar. Fish. Serv., Northeast and commercial fisheries for ocean Fisheries Center, Woods Hole, quahogs. N. Am. J. Fish. Man- Lab. Ref. No. 82-43. 25 pp. age. 2: 270-275. Muus, K. 1966. A quantitative I Masse, H. 1975. Feeding biology of 3-year-survey on the meiofauna Astropecten aranciacus. Cah. of known macrofauna communities Biol. Mar. 16: 495-510. in the Oresund. Veroeff. Inst. Meersforsch Bremerhaven, Sup-, Merrill, A. S., and J. W. Ropes. plement I1: 289-292. 1969. The general distribution of the surf clam and ocean quahog. Proc. Natl. Shellfish. Assoc. 59: Muus, K. 1973. Settling, growth and 40-45. mortality of young bivalves in the Oresund. Ophelia 12: 79-116. Merrill, A. S., and J. R. Webster. 1964. Progress in surf clam bio- National Marine Fisheries Service. logical research. Pages 38-47 in 1978-1982. Fisheries of the United C. J. Sindermann, ed. The States. U. S. Dep. Comm., Bureau of Commercial Fisheries, NOAA, Current Fishery Statistics Biological Laboratory, Oxford, Nos. 7500, 7800, 8000, 8100, Maryland: programs and perspec- 8200. tives. U. S. Fish Wildl. Serv. Circ. 200 pp. Nystrom, R. A. 1976. Spontaneous activity of clam intestinal muscle. Morse, E. S. 1919. Observations on Comp. Biochem. Physiol. 21: living lamellibranchs of New 601-610. I

20 O'Connor, J. S. 1976. Contaminant Ritchie, T. P. 1977. A comprehensive effects on biota of the New York review of the commercial clam Bight. Pages 50-631 in J. B. industries in the United States. Higman, ed. Proc. 28th Annu. U. S. Dep. Comm., NOAA, NMFS Gulf Caribb. Fish. Inst. Rep. 106 pp.

Ogren, L. 1969. New Jersey fish/ Ropes, J. W. 1968a. Hermaphroditism crustacean mortality. Smithson. in the surf clam, Spisula solidis- Inst. Cent. Short-Lived Phenom- sima. Proc. Natl. Shellfish. enon. Event No. 38-69. Assoc. 58: 63-65. Ogren, L., and J. Chess. 1969. A marine kill on New Jersey Ropes, J. W. 1968b. Reproductive wrecks. Underwater Nat. 6: cycle of the surf clam, Spisula 4-12. solidissima, in offshore New Jer- sey. Biol. Bull. (Woods Hole) Olsen, S. B. 1970. Some aspects of 135: 349-365. the ecology of Spisula solidissima. M. S. Thesis. University of Ropes, J. W. 1979. Biology and dis- Rhode Island, Kingston. 77 pp. tribution of surf clams and ocean quahogs off the northeast coast Parker, P. S. 1971. History and of the United States. Pages 47-66 development of surf clam har- in Proceedings of northeast clam vesting gear. U. S. Dep. industries: management for the Comm., NOAA Tech. Rep. NMFS future. Exten. Sea Grant Prog., Circ. 364. 15 pp. Univ. Mass. and Mass. Inst. Tech. Rep. SP-112. Patton, J. S., and J. G. Quinn. 1973. Studies on the digestive Ropes. J. W. 1980. Biological and lipase of the surf clam. Mar. fisheries data on the Atlantic Biol. (Berl.) 21: 59-69. surf clam, Spisula solidissima. U.S. Dep. Comm, NOAA, NMFS, Pearce, J. B. 1972. The effects of Northeast Fisheries Center Tech. solid waste disposal on benthic Ser. Rep. No. 24. 91 pp. communities in the New York Bight. Pages 404-411 in M. Ropes, J. W. 1982. The Atlantic coast Ruivo, ed. Marine pollution and surf clam fishery, 1965-1974. sea life. Fishing News Ltd., Lon- U.S. Nati. Mar. Fish. Serv. Mar. don. Fish. Rev. 44(8): 1-14. Pratt, D. M. 1974. Attraction to prey and stimulus to attack in the Ropes, J. W., and A. S. Merrill. predatory gastropod Urosalpinx 1970. Marking surf clams. Proc. cinerea. Mar. Biol. (Berl.) 27: Natl. Shellfish. Assoc. 60: 37-45. 99-106.

Prior, D. J. 1974. Role of the incur- Ropes, J. W., and A. S. Merrill. rent siphonal valve in the surf 1973. To what extent do surf clam. 88: 115-117. clams move? Nautilus 87: 19-21.

Reynolds, B. H. 1979. Trace metals Ropes, J. W., and A. S. Merrill. monitoring at two ocean disposal 1976. Historical cruise data on sites. U. S. Environmental Pro- surf clams and ocean quahogs. tection Agency Rep. NOAA, NMFS Data Rep. ERL EPA-600/3-79-037. 64 pp. MESA-17. 108 pp.

21 Ropes, J. W., and L. O'Brien. 1979. Shallenberger, R. S., S. M. Herbert, A unique method of ageing surf and B. A. Lewis'. 1975. Nature's clams. Int. Coun. Explor. Sea., immobilized enzyme. N. Y. Food Shellfish and Crustacea Comm., Life Sci. Q. 3 pp. C. M. 1979/K:28. 4 pp. Smucker, L., and R. A. Nystrom. i Ropes, J. W., and G. E. Ward, Jr. 1970. Control of gut movements 1977. The Atlantic coast surf by an intrinsic neural plexus in clam fishery-1974. U.S. Nati. the clam, Spisula solidissima. Mar. Fish. Serv. Mar. Fish. Fed. Am. Soc. Exp. Biol. 29: Rev. 39(5): 18-23. 89.

Ropes, J. W., J. L. Chamberlin, and Smucker, L., and R. A. Nystrom. A. S. Merrill. 1969. Surf clam 1972. Control of gut motility by fishery. Pages 119-125 in F. E. an intrinsic neural plexus in the Firth, ed. Encyclopedia of marine pelecypod Spisula. Comp. Bio- resources. Van Nostrand Rein- chem. Physiol. 41(4A): 731-748. hold, Co., New York. Steimle, F. W., Jr., and C. J. Sin- Ropes, J. W., A. M. Barker, and G. dermann. 1978. Review of oxygen E. Ward, Jr. 1975a. The Atlantic depletion and associated mass coast surf clam fishery-1972. mortalities of shellfish in the U.S. Natl. Mar. Fish. Serv. Mar. Middle Atlantic Bight in 1976. Fish. Rev. 37(8): 22-27. U.S. Natl. Mar. Fish. Serv. Mar. Fish. Rev. 40(12): 17-25. Ropes, J. W., A. S. Merrill, and G. E. Ward, Jr. 1975b. The Atlantic Steimle, F. W., Jr., and R. B. coast surf clam fishery-1973. Stone. 1973. Abundance and dis- U.S. Natl. Mar. Fish. Serv. Mar. tribution of inshore benthic fauna Fish. Rev. 37(12): 31-34. off southwestern Long Island, New York. NOAA, NMFS Tech. Saila, S. B., and S. D. Pratt. 1973. Rep. SSRF-673. 50 pp. Mid-Atlantic Bight fisheries. Pages 6-1 to 6-125 in S. B. Stephens, G. C., and R. A. Saila, coord. Coastal and offshore Schinske. 1961. Uptake of amino environmental inventory, Cape acids by . Hatteras to Nantucket Shoals. Limnol. Oceanogr. 6: 175-181. Mar. Exp. Stn., Univ. Rhode Island, Kingston, Mar. Publ. Sullivan, C. M. 1948. Bivalve larvae Ser. No. 2. of Malpeque Bay, Prince Edward Island. Bull. Fish. Res. Board Savage, N. B. 1976. Burrowing activ- Can. 77. 36 pp. ity in Mercenaria mercenaria and Spisula solidissima as a function Theede, H. 1965. Comparative experi- of temperature and dissolved mental investigations of the cellu- oxygen. Mar. Behav. Physiol. 3: lar freezing resistance of marine 221-234. bivalves. Kiel. Meeresforsch. 2: 153-166. Shallenberger, R. S., C. Searles, and Thorson, G. 1966. Some factors influ- B. A. Lewis. 1974. Laminaranase encing the recruitment and activity in the crystalline style of establishment of marine benthic the surf clam. Experientia 30: communities. Neth. J. Sea Res. 597-598. 3: 267-293. I

22 Thurberg, F. P., W. D. Cable, M. A. Wigley, R.' L., and K. 0. Emery. Dawson, J. R. Macinnes, and D. 1968. Submarine photos of com- R. Wenzloff. 1975. Respiratory mercial shellfish off Northwestern response of larval, juvenile, and United States. Commer. Fish. adult surf clams to silver. Pages Rev. 30(3): 43-49. 41-52 in J. J. Cech, Jr., D. W. Bridges, and D. B. Horton, eds. Wilbur, K. M. 1964. Shell formation Respiration of marine organisms. and regeneration. Pages 243-282 Proc. First Biomed. Sci. Symp., in K. M. Wilbur and C. M. 1975, Augusta, Maine. 211 pp. Y-nge, eds. Physiology of Mol- lusca. Academic Press, Inc., New York. Verber, J. L. 1976. Safe shellfish from the sea. Am. Soc. Limnol. Williams, A. B., and H. J. Porter.. Oceanogr. Spec. Symp. 2: 1971. A ten-year study of mero- 433-441. plankton in North Carolina estu- aries: occurrence of postmetamor- phal bivalves. Chesapeake Sci. Wenzloff, D. R., R. A. Greig, A. S. 12: 26-32. Merrill, and J. W. Ropes. 1979. A survey of heavy metals in the Yancey, R. M., and W. R. Welch. surf clam, Spisula solidissima, 1968. The Atlantic coast surf and the ocean quahog, Artica clam - with a partial bibliogra- islandica, of the mid-Atlantic phy. U. S. Fish Wildl. Serv. coast of the United States. U. S. Circ. 288. 13 pp. Nati. Mar. Fish. Serv. Fish. Bull. 77: 280-285. Young, J. S. 1973. A marine kill in New Jersey coastal waters. Mar. Pollut. Bull. 4: 70. Westman, J. R., and M. H. Bidwell. 1946. The surf clam, economics Zoellner, D. R. 1977. Water quality and biology of New York marine and molluscan shellfish: an over- resources. Typewritten MS. on view of the problems and the file at U. S. Dep. Comm., nature of appropriate laws. Rep. NOAA, NMFS, Northeast Fish. U. S. Dep. Comm., NOAA, Lab., Oxford, Md. NMFS. 226 pp. (Appendices).

23 50272-101 REPORT DOCUMENTATION I.REPORT NO. 2. 3. Recipient's Accession No.. PAGE FWS/OBS-82/11.13* 4. Titleand Subtitle Species Profiles: Life Histories and Environmental S. Report Date Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic) -- October 1983 Surf Clam 6.

7. Author(s) 8. Performing Organization Rept. No. Clemon W. Fay, Richard J. Neves, and Garland B. Pardue i). Performing Organization Name and Address 10. Project/Task/Work Unit No. Department of Fisheries and Wildlife Sciences Virginia Polytechnic Institute and State University 11. Contract(C) or Grant(G) No. Blacksburg, VA 24061

(G)

12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered National Coastal Ecosystems Team U.S. Army Corps of Engineers Fish and Wildlife Service Waterways Experiment Station U.S. Department of the Interior P.O. Box 631 14 Washington, DC 20240 Vicksburg, MS 39180

15. Supplementary Notes *U.S. Army Corps of Engineers report No. TR EL-82-4.

16, Abstract (Limit: 200 words) The surf clam (Spisula solidissima) is a dominant clam species in the mid-Atlantic 'region, and contributed 71.8% of all clam meats consumed in the United States between 1970 and 1974; total landings in 1981 were 20.9 thousand metric tons (46.1 million lb). :Surf clams live in the coastal zone from the Gulf of Maine to Cape Hatteras, North Carolina; they are most common in the breaker zone, but occur to depths of 70 m (230 ft). They reach sexual maturity in 2 years and spawn in the mid-Atlantic region from mid-July through mid-October, often with two spawning peaks per year; Larval stages are planktonic; upon settlement, they metamorphose into juvenile clams. Adults live buried in sandy or gravel substrates, with siphons extended above the bottom for feeding and respiration. Surf clams may live up to 25 years and reach a size of 225 mm (8.9 inches). Larvae tolerate water temperatures of 140 to 300 C (570 to 860 F), and salinities as low as 16 ppt. Adults tolerate 0. to 280 C (320 to 820 F) and 12.5 ppt salinity or higher. Depletion of dissolved oxygen in ocean bottom waters was the major-cause for large-scale surf clam mortalities off New York and New Jersey over the last two decades. Sewage, sludge, and heavy metals often cause accumulation of toxic materials in surf clam meats and force closure of beds to fishing to prevent human consumption of these toxic materials.

17. Document Analysis a. Descriptors Coastal Zone Feeding Clams Growth Distribution

b. Identifiers/OpenEnded Terms Surf clam Depth distribution ' Spisula solidissima Temperature requirements Substrate requirements

C. COSATI Field/Group 18. Availability Statement 19. Security Class (This Report) 21. No. of Pages Unlimited E Unclassified 23 20. Security Class (This Page) 22. Price Unclassified (See ANSI-Z39.28) OPTIONAL FORM 272 (4-77) (Formerly NTIS-35) Department of Commerce 77]

* Idw~as. DWvbM o 104lo~gleal SwkwWaskintpl. DC X Eastern Enorgy .04 LOWdUse Teen. Looloelt. WV 0 NaSIkflSCoastal Ecoosose Tess. SVd.5LLA

*Western awary sVWLa" wse TeeM Ft. Conni. Co

*Loosetuwsof A -- - I OfCes0

REGION 1 REGION 2 REGION 3 Regional Director Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service Lloyd Five Hundred Building, Suite 1692 P.O. Box 1306 Federal Building, Fort Snelling 500 N.E. Multnomah Street Albuquerque, New Mexico 87103 Twin Cities, Minnesota 55 111 Portland, Oregon 97232

REGION 4 REGION 5 REGION 6 Regional Director Regional Director Regional Director U.S. Fish and Wildlife Service U.S. Fish and WildlifeService U.S. Fish and Wildlife Service Richard B. Russell Building One Gateway Center P.O. Box 25486 75 Spring Street, S.W. Newton Corner, Massachusetts 02158 Denver Federal Center Atlanta, Georgia 30303 Denver, Colorado 80225

REGION 7 Regional Director U.S. Fish and Wildlife Service 1011 E. Tudor Road Anchorage, Alaska 99503 (DEPARTMENT OF THE INTERIOR U.S. FISH AND WILDLIFE SERVICE

As the Nation's principal conservation agency, the Department of the Interior has respon- sibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the.environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department as- sesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.