PACIFIC RAZOR CLAM - USGS National Wetlands Research Center

This series should be referenced as follows:U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life historiesand environmental requirements of coasta fishes and invertebrates. U.S. FishWildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL-82-4.This profile should be cited as follows:Lassuy, D. R., and D. Simons. 1989. Species profiles: 1 ife histories andenvironmental requirements of coastal fishes and invertebrates (PacificNorthwest)-- Pacific razor clam. U.S. Fish. Wildl. Serv. Biol. Rep. 82(11.89).U.S. Army Corps of Engineers, TR-EL-82-4. 16pp.

PREFACEThis species profile is one of a series on coastal aquatic organisms,principal ly fish, of sport, commercial , or ecological importance. The profilesare designed to provide coastal managers, engineers, and biologists with a briefcomprehensive sketch of the biological characteristics and environmentalrequirements of the species and to describe how populations of the species may beexpected to react to environmental changes caused by coastal development. Eachprofile has sections on taxonomy, 1 ife history, ecological role, environmentalrequirements, and economic importance, if applicable. A three-ring binder isused 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 Engineersand the U.S. Fish and Wildlife Service.Suggestions or questions regarding this report should be directed to one ofthe foll owing addresses.Information Transfer Special istNational Wetlands Research CenterU.S. Fish and Wildlife ServiceNASA-Sl idel 1 Computer Complex1010 Gause BoulevardSlidell, LA 70458U. S. Army Engineer Waterways Experiment StationAttention: WESER-CPost Office Box 631Vicksburg, MS 39180

CONVERSION TABLEMetric to U. S. CustomaryMu1 tiplymillimeters (mm)centimeters (cm)meters (m)meters (m)ki 1 ometers (km)ki 1 ometers (km)square meters (m2)square kilometers (km2)hectares (ha)liters (1)cubic meters (m3)cubic meters (m3)milligrams (mg)grams (g)ki 1 ograms (kg)metric tons (t)metric tons (t)kilocalories (kcal )Celsius degrees (OC)inchesinchesfeet (ft)fathomsstatute miles (mi)nautical miles (nmi)square feet (ft2)square miles (mi2)acresgallons (gal)cubic feet (ft3)acre-feetounces (oz)ounces (oz)pounds (lb)pounds (lb)short tons (ton)British thermal units (Btu)Fahrenheit degrees (OF)U.S.Customary to Metric25.402.540.30481.8291.6091.852To Obtaininchesinchesfeetfathomsstatute milesnautical milessquare feetsquare milesacresgal 1 onscubic feetacre- feetouncesouncespoundspoundsshort tonsBritish thermal unitsFahrenheit degreesmillimeterscentimetersmetersmeterski 1 ometerski 1 ometerssquare meterssquare ki 1 ometershectares1 i terscubic meterscubic metersmilligramsgramski 1 ogramsmetric tonsmetric tonskilocaloriesCel si us degrees

CONTENTSPagePREFACE ................................ i i iCONVERSION TABLE ........................... i VACKNOWLEDGMENTS ............................ v iNOMENCLATURE/TAXONOMY/RANGE ...................... 1MORPHOLOGY/IDENTIFICATION AIDS .................... 1REASON FOR INCLUSION IN SERIES .................... 3LIFE HISTORY ............................. 3Spawning and Larvae ......................... 3Juveni 1 es and Adults ........................ 4AGE AND GROWTH ............................ 5THE FISHERY .............................. 7History and Regulations ....................... 7Products and Clamming Sites ..................... 9Popu 1 at i on Dynamics ......................... 9ECOLOGICALROLE ............................ 10Food ................................ 10Sources of Mortality ........................ 10ENVIRONMENTAL REQUIREMENTS ...................... 11Temperature ............................. 11Salinity .............................. 12Oxygen ............................... 12Substrate .............................. 12DISEASE AND PARASITES ......................... 13CONCEKNS. GAPS. AND SPECULATIONS ................... 13LITERATURECITED ............................ 15

ACKNOWLEDGMENTSWe wish to thank Darrell Demory (Oregon Department of Fish and Wildlife,Newport) who provided much of the significant literature on razor clams as wellas extensive information on razor clam populations in Oregon. Jerry Lukas (ODFW,Portland) provided economic and catch data for the Oregon razor clam fishery. Wealso thank Kenneth Chew (University of Washington, School of Fisheries) for hisassistance and constant encouragement, and Terrance Link (Oregon Department ofFish and Wildlife, Astoria) who reviewed the manuscript. Thanks also go to DorisSmall, Alan Rammer, and Thom Hooper for their assistance in researchingWashington data to Adrian Hunter who prepared the manuscript.

Figure 1. Pacific razor clam (from Fitch 1953).PACIFIC RAZOR CLAMScientific name ...... ..Sil iqua patula(Dixon)Common name ........ Pacific razor clam(Figure 1)Other names ........ Northern razor clamCl ass ...................... Pel ecypodaOrder ....................... VeneroidaFamily ..................... .Sol enidaeGeographic range: Razor clams arefound on open sandy beaches fromPismo Beach in southern Cal i forniato the Aleutian Islands in Alaska.The distribution in the PacificNorthwest Region is shwn in Figure9MORPHOLOGY /IDENTI FICATION A1 DSFitch (1953) described the razorclam as follows: "Elongate shells,thin, flat and smooxh; covered with aheavy, glossy, ye1 1 owish peri ostracum,a prominent rib extending from theumbo to the margin on the inside ofthe valve. Foot large and powerful,never pi gmented. Siphons rat her shortand united except at tips. Umbosnearer anterior than posterior end.Attains a length of seven inches.Differs from the rosy (Solen rosaceus)and sickle (2. sicari us)azor clamsand the jack-knife (Tagel uscaliforni anus) clam by having a heavy,raised rib extending from the umbo tothe margin of the shell on theinside."Weymout h and McMi 11 in (1931 )further distinguished the relativelynonpigmented S. atula from a similarrazor clam, 5; a h y the presenceof "chocol ate-brown" col oration on thefoot, mantle, and siphon of -- S. alta.Differences in umbo position, growthpattern, vari abi 1 i ty, and rib di rectionwere also detailed. These samecharacteristics are also used to distinguishS. patula from S. sloati- - -

eMocrocks Beach -Willapa Bay detached spitsWASHINGTONIndian, Crescent, CWandamere Beach -OREGONMILES0 50 1001 KILOMETERSi. - .--CALIFORNIA. - '-r)Figure 2. Distribution of the Pacific razor clam in the Pacific NorthwestRegion. Long Beach, Twin Harbors, Copalis Beach, and Fbcrocks Beach inWashington and Clatsop Beach in Oregon are the primary razor clam beaches. Allothers are only intermittently populated to much extent.

which is found in subtidal areas only(Hertlein 1961 ). Quayle (1962) describedrazor clam shells as thin andbrittle; olive green in youth, changingto brown with age. Weymouth etal. (1925) noted that razor clams thathad never spawned had a "translucentappearance." Once spawning hadoccurred, the she1 1 s became very darkand did not regai n trans 1 ucence.REASON FOR INCLUSION IN SERIESThe razor clam is often referredto as the finest food clam availableon Pacific beaches. It is "the basisof economical ly important comnercialand recreational fisheries throughoutmuch of its range" (Breese andRobi nson 1981 ). Comrnerci a1 fishingfor razor clams has existed sincebefore the turn of the century but isnow being largely replaced byrecreational digging. Mi 11 ions ofclams are taken annually fromWashington and Oregon beaches. Thisincreasing popularity led Browning(1980) to write that "many Washi ngtonresidents, as well as a great numberof Oregoni ans , consider razor clamdigging Number One among outdooractivities."LIFE HISTORYS~awnina and LarvaeIn the Pacific Northwest, razorclams generally spawn in late springor early summer. Spawning seasons areprogressively later at more northernlocations. On the Alaskan Peninsula,for example, spawning may peak as lateas August (Weymouth et a1 . 1925).Peak spawning time for razor clams onWashington beaches varies from mid-Maythrough July. While the spawningseason is usual ly more protracted,McMillin (1924) estimated that 98% ofthe razor-clam spawn at Copalis Beach,Washington in 1923 occurred over onlya 2- to 4-day period in late May. Hefurther suggested that the degree ofsi mu1 tanei ty may be densi ty-dependent .Variations in local spawning times mayalso depend on food availability(Breese and Robinson 1981 ) or otherenvironmental conditions (see sectionon Temperature). In some populations,a second, much smaller spawning peakmay occur in late sumner or early fa1 1(McMi 11 in 1924). Some spawni ng maytake place throughout the year.Weymout h and McMi 11 i n (1931 )suggested that "neither arti fici a1propagation nor culture are feasible."However, the State of Washi ngton hasbeen operating a razor clam hatcherysince 1980. Breese and Robinson(1981 ) successfully induced spawningof S. patula in the laboratory byraising the concentration of thei rfood source. the dinoflaael late~seudoi sochry& s aradoxa,d~~~to 2-2.55T-Tmillion cells permi i iter. Thereis interest in artificial propagation,parti cul arly in Was hi ngton, because ofrecent losses of natural populationsto disease.Individual razor clams are eithermale or female rather than hermaphroditicwith the sex ratio of the adultclams being 1 to 1 (Nickerson 1975).Eggs and sperm are broadcast into thewater column where ferti 1 i zati onoccurs. Ovary and testes are normallyrather hard for the casual observer todifferenti ate. However, in advancedstages of development just prior , tospawning, eggs are granular and spermare very mi 1 ky (Weymouth et a1 . 1925).McMi 11 in (1924) pub1 is hed i 11 ust rationsand photographs of severaldevel opmental stages. He describedfree-floati ng eggs as "pear shaped,with a white spot in the center." Inhis observations of eggs and larvae,he noted that cleavage was completeand unequal and that zygotes soonbecame rounded rather than pearshaped.Vel igers were formed within10 days at 11-15 "C; by 3 weeks, theyhad taken on a "common clam shape"i.., round in valve view, heartshapedin cross section). At 5 weeks,a distinct foot had formed but the

entire animal was still transparent.At 8 weeks, the velum was gorle, theshe1 1 had become opaque, arid the clamshad begun to elongate. Settingoccurred at about 10 weeks. Breeseand Robinson (1981) noted in laboratorystudies (at 16.5 OC) that eggdiameter averaged slightly over 90 mm.Within 48 h, larvae were straighthingedand had reached 110mm.Metamorphosis, apparently comparableto McMillin8s "common clam shape"stage, occurred 20 to 25 days afterfertilization.Weymouth et a1 . (1925)reportedthat "eggs sink quite rapidly and arenot easily raised by surf action."However, McMi 11 i n (1924) suggestedthat larvae were easily moved andsubject to redistribution of "at leastseveral miles ." Both McMi 11 an (1 924)and Weymouth et a1 . (1 925) suggestedthat larval dispersal was limitedbecause of the brevity of the swimminglarval stage and the tendency oflarvae to remain in the sand.Juveni 1 es and AdultsAfter a 5- to 16-week larval1 ife span, juvenile clams begin to set(=settle out) and dig into the sand.Weymouth et a1 . (1925) reported thatthe density of razor clams 1 to 3months after setting "is sometimesenormous on the Washington coast" withdensities approaching 1500/ft(1 6,15O/m ) . Tegel berg and Magoon(1 969) reported average setting densitiesof 1,385/ft2 (14,900/m2) onCopali s Beach and 3 ,685/ft2(39,665/m2) on Mocrocks Beach, both inWashington, during the summer of 1966.Windrows of young clams covered thebeaches in patches "several inchesdeep and several acres in extent ."Densities from zero to 100/ft2(1,076/m2) are more common. Bourneand Quayle (1970) recorded highestsetting densities in the lower one-third of the intertidal zone in fine,firm, damp sand. In this same study,Bourne and Quayle observed that youngclams moved laterally along the surfaceof the sand as far as 30 cm.Thus, there may be a 1 imited amount ofdi rected redi st ri buti on of juveni 1 esafter setting. Rickard et al. (1986)hypothesized a complex mechanismi nvol vi ng growth and the movement ofsubtidal set clams onto intertidalbeaches. Once establ ished, juvenilesover 1 inch usually remain in placein the upper few inches of sand.Adult razor cl ams are usuallyabout 1 foot beneath the surface ofthe sand (McMill in 1924) and showvirtually no 1 ateral movement (Bourne1969). A1 though 1 ateral movement is1 imited, rapid vertical mobility ischaracteristic of the razor clam --as any first-time clam digger willagree. Vertical movement rates of 9inches to 1 foot per minute have beenmeasured (McMi 11 i n 1924; Schi nk et a1 .1983), but many clam diggers wouldswear that it was more. McMill in(1 924) reported one observation of arazor clam digging to a depth of 4 ft,9 inches. This unusual ability tomove so rapidly through the sand maybe a consequence both of the liquidityof subsurface sand (see section onSubstrate) and the digging mechanismof the razor clam. Unlike the morecommon flattened foot of many clams,the burrowing foot of the razor clamburrowing foot is "el ongate and nearlycyl indrical " (Weymouth et a1 . 1925).The foot is extended down into thesand, hydraul i cal ly expanded to serveas an anchor, and the muscles thencontracted to pull the clam downward(Weymouth et a1 . 1925). McMill in(1924) associated the evolution ofsuch mobility with the instability andtransport of beach sand.Large razor clams are densest inthe 1 ower i nterti dal zone (McMi 11 in1924; Bourne 1969; Ni ckerson 1975),though subtidal popul ations may a1 sobe substanti a1 . For example, thousandsof pounds of razor clams havebeen harvested at 20-40 ft in Alaskanwaters. The status of subtidalpopulations in the Pacific Northwest

is less well known. Preliminary workby the Washington Department ofFisheries (WDF) in 1983-85 indicatedthe presence of very few subtidaladults . However, Barrel 1 Demory(Oregon Department of Fish andWild1 ife, Newport, pers. comm.)reported diver observations along theOregon coast of a band of adult razorclams to 8 ft, a few on the steeperdrop-off to deeper water, and thencommon but less densely packed clamsto depths of at least 20 ft. Schinket al. (1983) even suggested that"offshore clam populations are considered broodstock for intertidalpopulations."The presence of substantialnumbers of subtidal juveniles is morefirmly established. McMi l lan (1 924)reported having col lected many smallclams out to 550 yards offshore atdepths of about 11 ft (3.3 m). Morerecently, Rickard et al. (1986)estimated subti dal densities of 38,000clams/m2 for juveniles from 1 t o 15 mmin length.Maturation in razor clams isapparently more closely linked withsize (length) than with age. Whilematurity is commonly reached at a sizeof about 10 cm (Weymouth et a1 . 1925),the age at maturity varies withgeographic location. Since growth ismore rapid on southern beaches in therange of the razor clam (see sectionon Growth), maturity is reached at alower age. Age at maturity isgenerally 2 years in the PacificNorthwest and 3-4 years in Alaska(Weymout h 1925). Maximum ageincreases sharply from 5 years inPismo Beach, Cal ifornia (Weymouth etal. 1931) to 9-11 years in the PacificNorthwest (McMi 11 in 1924; Weymouth eta1 . 1931 ) and 18-1 9 years in Alaska(Weymouth et a1 . 1931 ; Nickerson 1975).More recently, extensive harvest andhigher natural mortality have 1 imited1 ongevi ty in the Pacific Northwest toabout 7 years. A less pronouncedtrend in maximum size from 12 cm inPismo Beach to 16 cm in Alaska wassuggested by the early work of(Weymouth et a1 . 1931 ).The seasonal maturation of razorcl ams has a1 so been studied. Gonadaldevel opment is slowest duri ng wi nter ,increases as water temperature risesin spring, and peaks just before thespawning season in late spring orearly summer (Weymouth et al. 1925;Bourne and Quayle 1970). Some gonadalregeneration may occur through thefall (McMillin 1924; Bourne and Quayle1970). Bourne and Quayle alsoreported that females matured earlierin the season than males. At theirpeak, gonads may constitute 30% of thewei ght of the animal , excl usive ofshe1 1 (McMi 11 in 1924; Weymouth et a1 .1925). Estimates of fecundity forrazor clams from the Pacific Northwestbeaches seem generally to refer backto McMillin's (1924) estimate of 6-10million eggs. Ni ckerson (1975),however, estimated that fecundity inrazor clams from Alaskan beachesranged from 300,000 for a 40 mm clamto more than 118 million for a femaleof 180 mm in length.AGE AND GROWTHA compilation of the results of anumber of growth studies across thegeographic range of the razor clam isshown in Table 1. Since no consistentdifference has been noted between ma1 eand female growth rates, data for bothsexes are combined. In general,growth rates are hi gher (especi a1 lyin early years), and maximum lengthand lifespan are shorter, in southernthan in northern populations. Thesecharacteristics of growth and the morere1 i ably hi gh setti ng densities ledWeymouth and McMi 11 in (1931 ) andTegelberg (1964) to suggest thatWashington populations of razor cl amsare particularly well suited to withstandheavy exploitation. Continuedheavy exploitation and recent heavy1 osses to disease, however, have 1 edWDF to reduce limits and seasons.Some beaches of major importance now

Tab1 e 1. Mean length (cm) of the Pacific razor clams of different ages in differentlocalities.Plsmo, Crescent Clatsop, Long Copalis, Masset, Cordova, Swikshak, Hallo BayAgea cAb City, cAb OR' Beach, wAd WA~.~.' BC~ AK~S~ A K ~ V ~ AK~14.0~6 13.03 14.02 13.40~ 12.58 11.40' 12.74: 12.3713.58b 11.13' 12.917 13.32 13.84; 13.27 12.03; 13.70~ 13.1714.03 12.51 13.90'8 13.84 14.19~ 13.58 12.57' 14.19~ 13.6513.50' 14.67'9 13.51 14.50~ 13.69 13.08' 14.63~ 14.0614.09' 15.15'10 14.61 13.60' 14.94~ 14.4414.48~14.15' 15.25~ 14.7514.85'12 14.90; 15.61a 15.0813 15.01 16.12~ 15.3814 15.96~ 15.5015 16.72~ 15.8016 15.6117 15.7418 16.3119 16.74aListed ages represent the number of annuli present on shells. Actual agesvary from 4 to 8 months less than listed agesdepending on the time of spawning and the time of annulus formation.Sources: '=weymouth, McMillin, and Rich (1931); = Hirschhorn (1962), Table 3 totals column; = Tegelberg (1964),estimated from Figure 8; = McMillin (1924);' = Weymouth, McMillin, and Holmes (1925); = Nickerson (1975), Tables17 (Cordova) and 19 (Swikshak).sel domly provide the recreationaldigger a legal limit.Critical to the interpretation ofgrowth studies is the precision of theaging technique. In most of thestudies reported in Table 1, ages weredetermined by counting the number ofgrowth rings on the shell of the clam.McMillin (1924) described a tuck thatis formed between successive layers ofshell that leaves "a definite mark."He concluded that these marks wereannual rings (annuli ). Weymouth andMcMi 11 in (1931 ) and Hi rschhorn (1962)also concluded that such rings werevalid indications of an annual patternin she1 1 growth. Each of theseauthors noted the presence of otherchecks or fa1 se annuli formed during

spawning, storm disturbance.^, or otherevents that cause a reduction innormal growth rate. Each of theseauthors, however, a1 so felt that thesechecks were distinguishable fromannuli and that the basic agingtechnique was valid. Weymouth andMcMi 11 in (1931 ), in fact, general i zedits validity to include all lamellibranchs.However, Tegel berg (1964),who, like McMillan (1924) worked atCopal i s Beach, suggested that"distinct annuli appear to depend upona pronounced winter growth slowdown,and this frequently is lacking." Atleast for the population he wasstudying , Tegel berg concl uded that"aging by the ring method is of questionablevalidity." He preferred theuse of length-f requency techniques .As Weymouth et a1 . (1 925) pointedout, the growing season in Alaska "isroughly one - half as long as inWashi ngton ." Due to these shorter,more defined seasons, annuli are morepronounced, more numerous, and moreclosely placed in Alaskan than inWashington populations of the razorclam (McMillin 1924; Weymouth et al.1925). Regard1 ess of geographiclocation, growth rate is usuallyslowest during late fall and winter(Weymouth et al. 1925; Hirschhorn1962; Tegel berg 1964). Growth ratethen accelerates as the water warms inspring. Another factor that consisentlyaffects growth rate is locationwithin the intertidal zone. Tegel berg(1964), Bourne and Quayle (1970), andQuayle and Bourne (1972) all notedhigher growth rates near the low-tideline than in areas higher in theintertidal zone. Bourne (1969),commenting on this same pattern,suggested that the difference was dueto the longer time spent under water,and therefore increased feeding ti meand growth by the clams lower in theintertidal zone. We have seen no dataon the growth rates of subtidal razorclams. A very dense set may stunt thegrowth of some year-cl asses (Weymouthet a1. 1925; Hirschhorn 1962;Tegel berg and Magoon 1969).THE FISHERYHistory and RegulationsRazor cl ams have apparently beenused for personal consumption for avery long time, as they are known fromIndian middens (ref use heaps) alongthe Pacific coast (McConnel 1 1972).The razor clam industry along thePacific Coast "was pioneered by P.F.Halfarty at Skipanon, Oregon, in 1894"(Nickerson 1975). 'The market forfresh clams was limited at that time,but canning operations soon spreadcoastwide, from Oregon to theShe1 i koff Straits in Alaska (Weymouthet al. 1925). By 1915, 8 mil 1 ionpounds of razor clams (3.2 mi 11 ion lbcanned) were harvested and processedannual ly in Washington alone (Schinket al. 1983). Although some majorclamming grounds (e. g. , W i l lapa Bayand Grays Harbor) were sti 11 "total lyunused" (McMi 11 in 1924), regulatorychanges were already afoot. Due todeclining numbers of older clams,states began to impose restrictionson commercial harvest (Weymouth andMcMillin 1931; Schink et al. 1983).Initial restrictions took the form ofclosures during the spawning seasonand size limitations.A developingrecreational use ofrazor cl ams remai ned largely unrestrictedunti 1 the late 19201s, whenbag and size limits began to beimposed . It was eventual 1 y recogni zedthat minimum si ze requi rements were oflittle use since improperly replantedrazor clams were not likely to survive(D. Demory, pers . comn. ) . Consequent -ly, bag limits now are accompanied bythe stipulation that all razor clams,regard1 ess of size or condition, mustbe kept and counted toward the dailybag. It is hoped that this stipulationwill go a long way towardeliminating the waste that has plaguedthe fishery throughout its existence.McMi 11 in (1924) estimated that theamount of razor clams wasted (dug anddiscarded due to size or injury) wasnearly equal to the amount used.Wastage in 1949 was estimated at

15%-28% (Tegel berg et al. 1971). This As late as 1940, the commercialpercentage has declined over the past catch in Oregon still composed 80% of10 years (Table 2), but wastage is the razor clams taken (Link 1980).still a significant source of After World War 11, however, themortal i ty resulting in numerous numbers of tourists and residentemergency closures in Washington. recreational di ggers of razor cl amsTable 2. Numbers, pounds, and value to fishermen (all in thousands) of razorclams harvested by recreational (incl udes wastage) and commercial diggers from1977-1 986. A1 1 weights are who1 e (unshucked) weights.-- -washingtonaOregonbRecreational ~omrnerclal~ Recreational CornrnerclalCatch Wasde Landings Value Catch Waste Landinas ValueYear (No.) (%) (Pounds) ($) (No.) (%) (NO.) (Pounds) ($)Average 6,428 6.2 82 77 683 11.6 142 26.0 35.3al 977-1984 recreational catch numbers from Washington State Sport Catch Report series; commercial catch data fromWashington Fisheries Statistical Report series; 1985 and 1986 data provided by Doug Simons.b~ecreational take numbers from Link (1986); 1977-1985 commercial catch data from Oregon Department of Fish andWildlife's "Pounds and Values" series; 1986 commercial data from Jerry Lukas (ODFW, pers. mmm.).'Number of commercially taken clams not reported for Washington. Numbers per pound may vary from 4 to 9 and aretherefore not easily convertible.d~ercent wastage for Washington computed as weighted mean of wastage values reported for Long Beach, Twin Harbor,Copalis, and Mocrocks in WDF Sport Catch Report.eCommercial razor clam fishery data limited to Willapa spits after 1978; i.e., does not include fishery on Quinault IndianReservation.'EI Nino year.gTotal closures in 1984 and 1985 due to parasitic infection of clams.h~hortened season.

increased sharply. Competition fromAt1 antic Coast canning companiesfurther led to the demise of many WestCoast clam fisheries (Nickerson 1975).'The last major public beach in Washingtonwas closed to commercialharvest in 1968. Only the W i l lapa Bayspits and the Quinault Indian Reservation now mai ntain commerci a1 fisheries.Recreational take now far exceeds commercialtake (Table 2). The QuinaultTribal Council closed its beaches tonon-Indian fishermen in 1969. Schinket a1 . (1983) provided a concisereview of the Pacific razor clamfishery, its regulation, and juri sdi c-ti onal conf 1 i cts .Products and Clamning SitesThe primary tool of both commercialand recreational diggers is anarrow-bl aded shovel call ed a cl am gun.Tubular suction devices similar tothose used for ghost shrimp are alsoused. Clams are dug individually.The appropriate place to dig is markedby a shallow depression ("show") leftin the sand when the clam retracts itssiphon. Since concent rati ons of 1 argeclams are densest in the lower intertidal, minus tides are particularlygood times for digging.Commerci a1 cl amni ng seasonscoincide with the period of peakproduct qua1 i t y and yield (Ni ckerson1975) immedi ately before the spawni ngseason. Canned, minced clams wereformerly the major product. Mostcommerci a1 l y harvested razor clams nowgo to the fresh clam market or areused as crab bait.The digging and processing ofrazor clams is 1 abor-i ntensi ve, anddemand for these clams consistentlyexceeds supply. These condi ti onscreate relatively high and stableprices. Schink et a1 . (1983) reportedthat razor clams sold for up to 95f/lbunshucked, $2.20 shucked, and retai 1 edfor as much as $6.50/1b at the primarymarkets in Portland and Seattle. Asmuch as $2.20/1b for unshucked clamswas paid to comnercial diggers inOregon in 1987. Though a stable highprice and excess market demand lendthemsel ves to "aquacul tural considerations"(Schink et a1 . 1983), nopri vate aquaculture operations yetproduce razor clams. Since 1980, theState of Washington has producedmi 11 ions of hatchery-reared razorclams for use in its experimentalseeding program. Another enhancementproject invol ved the transplantationof over 90 million small (1-15 mm)razor clams from subtidal areas to theintertidal zone (Ri ckard and IVewman1986).Razor cl ams are dug recreational -ly throughout the Pacific Northwest.However, thei r avai 1 abi 1 i ty is muchlower in California and the southernand central coast of Oregon than tothe north. Over 90% of Oregon's razorclams are dug along the 18-mi stretchof Clatsop Beach on the northernOregon coast (Link 1980). The primaryrazor clam beaches of Washington areLong Beach, Twin Harbors, Copalis, andMocrocks; Kalaloch Beach is used tolesser extent (Schink et al. 1983).Although the State of Washingtonrequires a license for both commercialand recreational harvest of razorclams, Oregon does not currentlyrequire recreational diggers to belicensed. However, the influx of nonresidentsto Oregon beaches during1984 and 1985, when disease problems(discussed later) forced the closureof Washington beaches to razor clamdigging, created pressure for theassessment of 1 i cense fees.Population DynamicsBreese and Robinson (1981 )observed that, under laboratory condit i ons , most larval deaths occurredat the time of metamorphosis. We have

seen no comparable study under naturalconditions. The determinants of thewide vari abi 1 i ty in razor clam recruitment,therefore, remain uncertain. Itis noteworthy, however, that heavysets may not be enti rely beneficial tothe species. Tegelberg and Magoon(1969) noted that high oceanic survivaland massive setting may lead toreduced growth and increased mortal i tyin the current-year class and toreduced growth rate in alreadyestablishedadults. During one suchmassive set, the Washington Departmentof Fisheries transplanted over 300million razor clams to less successfullyrecruited beaches. Thoughsurvival was not high, it was concludedthat the transfer of set clamsmade a worthwhile addition to areaswith a poor natural set (Tegelberg andMaqoon 1969).McMill in (1924) estimated a 99%mortality rate for razor clams overthe first 8 months of life. Othershave estimated post -setti ng survivalrates, but are inconsistent as to thepattern of survival at progressi vel ygreater ages. Nickerson (1975)estimated annual survivals of 9% from1 to 2 years, 30% from 2 to 3 years,and 40% thereafter. The pattern ofsurvival in a study by Link .(1980) wasinverted; survival was highest (15.5%)at age 0 and lowest (0.1%) for thoseover 3 years of age. Link suggested,however, that his results may havebeen biased by disproportionately 1 owreturn of tags from large clams.Hi rschhorn (1962) and Link (1980)arrived at similar estimates of totalinstantaneous mortality rate (Z) of2.52 and 2.34, respectively, whichcorrespond to annual mortalities (A)of 92% and 90%. Hirschhorn (1962)further separated Z into its fishing(F = 1.78) and natural (M = 0.74)mortal i ty components. Thi s breakdownis similar to that of Nickerson (1975)who attributed one-thi rd to one-ha1 fof the annual mortality rate tonatural causes. Hi rschhorn Isestimate of natural mortal i ty i ncl udedwastage.ECOLOGICAL ROLEFoodTypical of bivalve moll uscs, therazor clam filters its food from thesurrounding water. Tegel berg andMagoon (1969) i denti fi ed Chaetoceros-armatum as "the princ'ipal foodorganism available to the razor clamduring the period October to April"(1966-67) a1 ong the Washington coast.Lewin et al. (1979a) estimated that- C. armatum composed 80%-100% of thediet of the razor clam. Unfortunately,no mention was made of the specificsof thei r esti mation procedures, i .e.,sampling times and frequency, samplesize, and technique for gut contentanalysis . Several other diatoms, particularlyAsterionel la social is, arealso abundant in the surf zone alongthe Oregon and Washington coasts(Ji jina and Lewin 1983) but are oflesser importance as a food source forrazor clams. Lewin et a1 . (1979a)also cited the coincidence of highsurf diatom standing crops withproducti ve razor cl am beaches. Breeseand Robinson (1981) fed the dinof1 age1 1 ate ~seudoi sochrysi s paradoxato razor clams in laboratory aquaria.Lewi n et a1 . (1979b) concl udedthat amnoni urn excretion by dense populationsof razor clams could play asi gni fi cant rol e in overall nitrogencycles of the surf environment. Inparticular, ammonium may serve as anitrogen source for the mai ntenance ofa1 gal populations.Sources of Mortal i tyThe time during and immediatelyafter setting is a particularly susceptiblestage. Dense sets of razorclams may attract large numbers ofavian predators. McMillin (1924)estimated that more than 20,000seagull s were preying on newlyrecruited razor cl ams a1 ong Copal isBeach, Washington. He commented that

the gulls pick up "every clam thatshows on the surface of the sand andin the edge of the breakers."Interestingly, the gulls had also"learned to push their feet into thesand... shake the sand... causing theyoung clams to rise to the surface."This same observation has been made byone of the authors (DS) of the Northwesterncrow, Corvus cauri nus. Theyare also capabwdigging up smallclams by scratching the sand's surface.Other predators mentioned byMcMi 11 in were ducks and surfperches .Si mi 1 arl y , Tegel berg and Magoon(1969) observed that "throughout theperiod of dense sets, shorebirds ofthe sandpi per group (Scol opaci dae)were observed in great numbers feedingon razor clams." There was also predationon the clams by large numbersof glaucous-winged gull s (Laruslaucescens) and sea ducks, primarilyjurf scoters (Melanitta ers icilm),and white-winged sc*.f usca) . Small Dungeness crabs(Cancer magister) were also "unusuallyabundant i n shall ow inshore 1 agoonswhere they fed on set clams." Personalobservations of stomach contentsof green and white sturgeon by one ofthe authors (DS) showed that hundredsof 1-10 mm razor clams had beeningested. Hogue and Carey (1982)reported that "young-of-the-year"razor clams were among the bivalveseaten bv newlv recruited Enal i sh sole(Paro hi s vetulus). We hate seen nor& p m o n by any animal onlarval or adult razor clams.A major source of mortality,especially for young razor clams, isthe scouring effect of winter storms(McMi 11 i n 1924; Tegel berg and Magoon1969; Bourne and Quayle 1970). Bourneand Quayle suggested, in fact, thatprotection from winter storms waslargely responsi bl e for re1 ati velyhigh population numbers at MassetBeach, British Columbia. Anothersource of mortality in the past wasautomobile traffic (McMillin 1924).Auto races held on the hard-packedbeaches were eventually suspendedduri ng August to avoid crus hi ngnewly set razor clams. Other knownsources of mortal i ty are discussed1 ater.ENVIRONMENTAL REQUIREMENTSTemperatureSayce and Tufts (1971 ) determinedfrom laboratory experiments that thetemperatures at which razor clam mortali ties occurred varied with bothabsolute temperature and period ofexposure. Mortal i ties began after 4hours at 21 "C, after 3 hours at27 "C, after 2 hours at 28 "C, andafter 1 hour at 29 "C. They concludedthat the "LDs~ appears to range fromabout 22.5 "C for razor clams exposed4 hours to about 27.5 "C for razorclams exposed 1 hour to warmed seawater."Bourne and Quayle (1970)attri buted decreased density of razorclams from July to September partly tolethal temperatures on the BritishCol umbi a beaches that they i nvesti -gated. Air temperatures near thei rstudy sites reached 23-29 " C duri nglow tides.Temperature and the pattern oftemperature change have been used toexplain spawn timing. A1 1 investi -gators who reported on the relation oftemperature to spawning behavioragreed that an abrupt rise in ambienttemperature was the trigger to theinitiation of spawning. Only theactual temperature and requi rementsfor prespawni ng temperature hi storyvaried among reports. Weymouth eta1 . (1925) noted that spawning byrazor clams on Washington beaches tookplace on a sharp rise in water temperatureat the "critical temperature" of13 "C. They suggested that thistemperature was a1 so consistent withtemperatures in Alaskan waters at thetime of spawning. However, Bourne andQuayle (1970) and Nickerson (1975)have suggested that a 1 ower triggeringtemperature may be more realistic forlocations north of Washington.

Bourne and Quayle (1970) notedthat 13 O C was not often reached inwaters along British Columbia beachesand suggested that spawning might be1 inked to some factor (s) associatedwith upwelling, tidal cycle, and foodavai 1 abi 1 i ty. The experiments ofBreese and Robinson (1981 ) lendcredence to food availability as acontributing factor. Nickerson (1975)suggested a more complex set of conditionsas the cue to razor clamspawning. He be1 ieved that some typeof cumulative temperature factor(degree-days) was a necessary precursorto the actual triggering effect ofa temperature rise. He reported thatspawning began in Alaska after anabrupt rise from a mean temperature of45 OF (7.2 OC) to 47 OF (8.3 OC).Sal i n i tyWe found no data, experimental orfield-gathered, on the effects ofsalinity on razor clams. McMillin(1924), however, suggested that cl amsthat lived relatively high on thebeach may be killed by heavy rainsthat reduce sal ini ty. Tegel berg(1964) suggested that the influence ofthe Columbia River in loweringsal i ni ti es at Long Beach, Washington ,might account for the slower growthrate there than in the more northern,hi gher-sal i ni ty areas near Copal isBeach, Washington.OxygenNo data on the oxygen requirementsof razor clams were found.McMil lin (1924) mentioned oxygen as afactor in razor clam biology. Hesuggested "the one factor that wouldappear to have the greatest effect onthe vertical distribution of razorclams is the oxygen content of thewater." No estimate of actualrequirements was made, but he wrotethat razor clams will not live whereaeration of the water is limited.Subst rateDescriptions of razor clamhabitat consistently i ncl ude suchdescriptors for beaches as stab1 e,open ocean, fully exposed, surfpounded, broad, flat, uni form, hard,and sandy (McMill in 1924; Fitch 1953;Quayle 1962; Browning 1980). Severalof these terms have been discussed indetai 1 by various authors. McMi 11 i n(1924) suggested that the fi ne-grai nsand and gentle slopes of razor clambeaches aided in holding water in thesand between tides. These traits, heconcluded, gave the beach itstypi cal ly hard surface and "quicksand"subsurface texture. McMi 11 in a1 sonoted that these beaches containedlittle organic matter.Browning (1980) wrote that thepounding surf was important to themai ntenance of beaches "where currentsinduce quick and continual change ofwater over the beds." This is consistentwith the earlier mention byMcMi 11 in of the probable high oxygendemands of razor clams. The lack of arenewal of oxygen or possibly siltationproblems may a1 so he1 p explainthe conclusion of McMillin (1924) thatrazor clams "will not grow insheltered bays."Hi rschhorn (1962) describedCl atsop Beach, Oregon, more speci f i -cally as having a "flat beach-faceslope (1:70) and small sand (0.2 mm) ."He noted that other productive beacheshad even lower slopes and finer sand.Nickerson (1975), in a survey ofA1 askan razor clam beaches, observedthat grain si ze on producti ve beacheswas very uniform and averaged 0.16 to0.19 mm in diameter. However, hebelieved that a more critical characteristicof productive beaches was alow clay fraction. Densities of razorclams were highest on beaches with thelowest percentages (0.0005% to 0.85%)of particles less than 0.005 mm indi ameter. Ni ckerson a1 so fel t thatsi 1 t -1 aden sediments "may causesuffocation in early life stages of

azor clams." He estimated thatthe "critical region for lethal levelsof fine substrate particles less than0.005 mm in diameter may be approximately2.2% of the total substratecomposition."Nickerson (1975) a1 so estimatedupper habitable tide level (feet abovemean lower low water). For beacheswithin the Pacific Northwest region,his estimates were as follows: PointChehalis and Long Beach, WA, 3.4 and3.1; Warrenton and Port Orford, OR,3.1 and 2.7; and Crescent City, CA,2.6.DISEASE AND PARASITESThe occurrence of a previouslyunknown disease caused the completeclosure of the razor clam fishery inthe State of Washington in 1984 and1985. The cause of the disease wasidentified as "nuclear inclusion X"(NIX), a prokaryotic pathogen, whichcauses an "inflammatory overgrowth ofepithel ial cel Is, congestion ofrespiratory spaces in the gill s,rupture of gill epithelial cel Is,obstruction of gill epi theli a1 cell s,and the initiation of secondaryinfections" (Elston et al. 1986).Plortality appears to depend on prevalenceand intensity of infection.NIX was "virtually 100%" present inthe vicinity of Copalis and bbcrocksbeaches from June 1983 to June 1985(Elston et al. 1986). Between June1983 and January 1984, the pathogen"presunptively caused a 95% loss" ofrazor clams from beaches along thecentral coast of Washington (Elston eta1 . 1986). Prevalence and intensitydecreased both north and south of thecentral Washington beaches. The pathogenwas neither found at, nor northof, the Queen Charlotte Islands inBritish Colunbia. In Oregon, theprevalence was high--92% at AgateBeach and 100% at Clatsop Beach (Link1986)--but intensities were low enoughthat mortalities were not a signi -ficant problem.The nemertean worm Ma1 acobdell agrossa lives commensally 'in therazor clam (Oregon Fish Corrmission1963). These 1- to 2-inch wormsattach on the inside of the siphon butare of no harm to the clam or to thehuman consumer. A commensal pea crab,Pinnixa sp., is also routinely foundi n a m samples in Washington.Paralytic shellfish poisoning isof widespread concern to consumers ofbivalves. Browning (1980) reportedthat there had been no validatedrecord of this problem in the historyof razor clam fisheries. However,testing by the Washington StateDepartment of Social and HealthServices in 1984 revealed high levelsof paralytic shellfish poison in razorclams. If the clam season had beenopen, Washington would have had toimpose an emergency closure (FrankCox, Washi ngton Department of Soci a1and Health Services, Olympia; pers.comm.). Similar findings have beenmade from several Alaskan razor clampopulations between 1985 and 1987(Richard Barrett, Alaska Department ofEnvironmental Conservation, Divisionof Environmental Heal th, Juneau ; pers.comm. ).CONCERNS,GAPS, AND SPECULATIONSPrimary among our concerns isthe effect of siltation, which occursduring silt-generating activities(e.g., dredging), in the vicinity ofsignificant razor clam beaches. Adiscussion of the serious impacts ofsi 1 tation, especially during andafter the time of setting, was givenby Nickerson (1975).The effects of low sub-surfaceoxygen is another concern. McMillan(1924) felt that razor clams requirerelatively high levels of dissolved

oxygen, although data on the subjectare lacking. In an era of increasingnearshore oil exploration, in theevent of an oil spill, sub-surfaceoxygen may be affected. We are notprepared to say how that would impactrazor clams.Another gap in our understandingof razor clam biology is the realextent and importance of subtidalpopulations. Understandably, roughsurf has prevented such data frombei ng routinely gathered. At aminimum, however, it seems that theconcept of these subtidal populationsacting as brood stock for intertidalpopulations should be verified. Earlyand recent authors seem to differ onthe topic of larval drift. Is there alarge pool of far-ranging larvae inoffshore waters, or is larval driftlimited and must local stocks producerecruits for thei r own rep1 acement?Finally, a speculation: re1 ati velyfast growth; the recent successesof enhancement efforts in spawning,reari ng , and transplanting razor cl ams ;and a high, stable market price suggestto us (as it did to Schi nk et a1 .1983) that razor clam aquacul turaloperations remai n a distinct futurepossi bi 1 i ty.

LITERATURE CITEDBourne, N. 1969. Population studieson razor clams at Masset, BritishColumbia. Fish. Res. Board Can.Tech. Rep. 118. 24 pp.Bourne, N., and D.B. Quayle. 1970.Breeding and growth of razor clamsin British Columbia. Fish. Res.Board Can. Tech. Rep. 232. 39 pp.Breese, W.P., and A. Robinson. 1981.Razor clams, Siliqua patula (Dixon):gonadal devel opment , inducedspawning , and 1 arval rearing.Aquaculture 22: 27-33.Browning, R.J. 1980. Fisheries ofthe North Pacific. A1 aska NorthwestPub1 . Co., Anchorage, A1 aska.434 pp.El ston, R.A. 1986. An i ntranucl earpathogen [nuclear inclusion X (NIX)]associated with massive mortalitiesof the Pacific razor clam. SiliauaElston, R. A., A. S. Drum,M.T. W i l kinson, and J.R. Skalski .1986. Pathology of the razor clam.Wash. Dep. Fish. Service ContractNo. 1533.Fitch, J.E. 1953. Common marinebivalves of California. Calif. FishGame Fish. Bull. 90.Hertlein, L.G. 1961. A new speciesof Sili ua (Pelecypoda) from westernNorth +!IT erica. Bull. So. Calif.Acad. Sci . 60(1) :12-19.Hirschhorn, G. 1962. Growth andmortality rates of the razor clam(Si liqua patula) on Clatsop Beach,Oregon. Fish Corn. Oreg. Contrib.No. 27. 55 pp.Hogue, E.W., and A.G. Carey, Jr.1982. Feeding ecology of 0-ageflatfishes at a nursery ground onthe Oregon coast. U.S. Fish. Bull.80(3) : 555-565.Jijina, J.G., and J. Lewin. 1983.Persistent blooms of surf diatoms(Baci 11 ariophyceae) along thePacific coast, USA. 11. Patternsof distribution of diatom speciesa1 ong Oregon and Was hi ngton Beaches(1 977 and 1978). Phycol ogi a 22(2) :11 7-1 26.Lewin, J., C. Chen, and T. Hruby.1979a. Blooms of surf-zone diatomsalong the coast of the OlympicPeninsula, Washington. X. Chemicalcom~osition of the surf diatom~haetoceros armatum and its majorherbi vore. thei fi c razor clamSili ua patula. Mar. Biol.d 2 6 5 .Lewin, J., J.E. Eckman, and G.N. Ware.1979b. Blooms of surf -zone diatomsalong the coast of the OlympicPeninsula, Washington. XI.Regeneration of ammoni um in thesurf environment bv the Pacificrazor clam, Siliqua patula. Mar.Biol . 52: 1-9.Link, T. 1980. Mortality rates ofthe razor clam based upon the 1973

tagging study on Gearhart Beach.Oreg. Dep. Fish Wildl. Info. Rep.Link, T. 1986. 1985 razor clamfishery. Oreg. Dep. Fish Wildl.Shellfish Invest. Info. Rep.McConnel 1 , S. J. [1972]. Proposedstudy of the spawning and larvalrearing of the Pacific razor clam(Sil iqua patula). Unpublishedproposal to Washington Departmentof Fisheries, Olympia.McMillan, H.C. 1924. The lifehistoryand growth of the razor clam.34th Annu. Rep., Washington Departmentof Fisheries, Olympia.Nickerson, R.B. 1975. A criticalanalysis of some razor clam (Si li uaatula Dixon) populations in &k Dep. Fish and Game, Juneau.194 pp.Oregon Fish Commission. 1963. Razorclams. Oreg. Fish Comm. Educ. Bull.No. 4. 13 pp.Quayle, D.B. 1962. The Pacific razorcl am. Trade News 14(9) : 8-9.Quayle, D.B., and N. Bourne. 1972.The clam fisheries of BritishColumbia. Fish. Res. Board Can.Bull. 1979. 70 pp.Rickard, N.A., A. Ramner, andD. Simons. 1986. Aspects of theearly subtidal life history of thePacific razor clam, Sili ua fatulaDixon, off the coast Te o Washingtonstate. Abstract presented at Natl .Shel 1 fish. Assoc. Annu. Mtg.,Seattle, Washington. June, 1986.Rickard, N.A., and K.A. Newman. 1986.Development of technology for harvestingand transplanting subtidaljuveni 1 e Pacific razor clams,Sila ua patula Dixon along the coastA h , ngton state. Abstractpresented at Nat 1 . Shel 1 fi sh. Assoc.Annu. Mtg., Seattle, Washington.June, 1986.Sayce, C.S., and D.F. Tufts. 1971.The effect of high water temperatureon the razor clam, Si 1 i qua fatul:(Dixon). Proc. Natl. Shel fishSchink, T. D., K. A. McGraw, andK.C. Chew. 1983. Pacific coastclam fisheries. Uni v. Washington.HG-30.Tegelberg, H.C. 1964. Growth andring formation of Washington razorclams. Wash. Dep. Fish. Fish. Res.Pap. 2(3) :69-103.Tegelberg, H.C., and C.D. Magoon.1969. Growth, survival, and someeffects of a dense razor clam set inWashington. Proc. Natl . Shel lfish.ASSOC. 59: 126-135.Tegel berg, H.C., C.D. Magoon,M. Leboski, and J. Westby. 1971.The 1969 and 1970 razor clamfisheries and sampling program.Wash. Dep. Fish., Prog. Rep. 109 pp.Weymouth, F.W., and H.C. McMillin.1931. Relative growth and mortalityof the Pacific razor clam (Siliquapatula, Dixon) and their bearing onthe commerci a1 fishery. U.S. BureauFish. Bull . 46:542-567.Weymouth, F.W., H.C. McMill in, andH.B. Holmes. 1925. Growth and ageat maturitv of the Pacific razorclam, SilWiqua patula (Dixon).U.S. Dep. Commerce, Bureau Fish.Doc. No. 984: 201-236.Weymouth, F.W., H.C. McMillin, andW. H. Rich. 1931. Latitude andrelative growth in the razor clam,J. Exp. Biol.

SO272 -101REPORT DOCUMENTATIONPAGE4. Title and SubtitleSpecies Prof i les: Life Hi stories and Environmental Requirements ofCoastal Fishes and Invertebrates (Pacific Northwest)--Pacific- razor clam7. Author(s1Dennis R. ~assuy~and Douglas ~irnons9. Performing Organiration Name and AddressaOregon Cooperative Fishery Research UnitOregon State University104 Nash HallCorvallis. OR 97331-3803 Montesano. WA 9856312. Swnsorlng Organization Name and Address1. FEFQRT.No.Biological Rport 82(11.89)*2.3. Rec~poent's Access~on NO.5. Rewrc DateJanuary 19896.National Wetlands Research Center U.S. Army Corps of EngineersU.S. Department of Interior Waterways Experiment StationFish and Wildlife Service P.O. Box 631Washington, DC 20240 Vicksburg, MS 3918013. TYPO of Rewe L Perlod CoveredI--15. Supplementary NotesII *U.S. Army Corps of Engineers TR EL-82-416. Abstract (Limit: 200 words)Species profiles are literature summaries of the taxonomy, morphology, distribution,1 ife history, ecological role, fishery (when appropriate), and environmentalrequirements of coastal aquatic species. They are prepared to assist coastalmanagers, engineers, and biologists in the gathering of information pertinent tocoastal development activities. The Pacific razor clam has a long history of humanconsumption on the west coast. Turn-of-the-century commercial canning operationshave given way to today's extensive recreational fishery. Razor clams spawn inlate spring and early summer in the Pacific Northwest and recruit to flat, sandybeaches in late summer. Greatest densities of large clams occur in the lowerintertidal zone. Razor clams grow and mature faster but attain a lower maximumsize and age in the southern part of their range. They are noted for their unusualability to dig very rapidly through the subsurface sand. Silt-generating activitiesshould be avoided in the vicinity of razor clam beaches, as juveniles are susceptibleto suffocation.17. Document Analysis a. DescriptorsPExposed beaches Movement Recreational diggers Si 1 tationIntertidal zone Growth Wastage Cl amsSetlrecrui tment Feeding habits Temperature AquacultureFisheries Predators Sedimentsb. IdentlReo/Open-Ended TermsPacific razor clamSiliqua patulaLife historyEnvironmental requirementsc. COSATI FieldlGroup18. Availability StatementUnl id ted(See A NSI-Z~~.~~)I19. Secur~ty Class (Th~s RcwrOUnclassified20. security Class (This pale)UnclassifiedI21. No. of Pages16P. PriceOPTIONAL FORM 272 (4-7n(Fornwrly NTlS35)Department of CornmercaI

TAKE PRIDEin AmerzcdDEPARTMENT OF THE IWTERIORU.S. FISH AND WllDLlA SERVICEAs the Nation's principal conservation agency. the Department of the Interior has responsibilityfor most of our .nationally owned public lands and natural resources. This includesfostering the wisest use of our land and water resourcm, protecting our fish and wildlife,preserving thsenvironmental and cultural values of our national parks and historical places,and providing for the enjoyment of life through outdoor recreation. The Department assessesour energy and mineral resources and works to assure that their development is inthe best interests of all our people. The Department also has a major responsibility forAmerican Indian reservation communities and for paople who live in island territories underU.S. administration.