Fish and Wildlife Service

U.S. Department of the Interior

Coastal Ecology GroupWaterways Experiment Station

U.S. Army Corps of Engineers

T~s I ~$Dull \JA'-E \~

FWS/OBS-82/11.10TR EL-82-4Ocotber 1993

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

ATLANTIC SILVERSIDE

by

Clemon W. Fay, Richard J. Neves,Department of Fisheries and

Virginia Polytechnic InstituteBlacksburg, VA

and Garland B. PardueWildlife Sciencesand State University24061

Project ManagerLarry Shanks

Project OfficerNorman Benson

National Coastal Ecosystems TeamU.S. Fish and Wildlife Service

1010 Gause BoulevardSlidell, LA 70458

This study was conductedin cooperation withCoastal Ecology Group

U.S. Army Corps of EngineersWaterways Experiment Station

Performed forNational Coastal Ecosystems TeamDivision of Biological Services

Fish and Wildlife ServiceU.S. Department of the Interior

Washington, DC 20240

CONVERSION FACTORS

Metric to U.S. Customary

Multiply To Obtain,

millimeters (mm)centimeters (cm)meters (i)kilometers (km)

0.039370.39373.2810.6214

10.760.38612.471

inchesinchesfeetmiles

square meters (mL)square kilometers (kin2)hectares (ha)

liters (1)cubic meters (m3 )cubic meters

milligrams (mg)grams (gm)kilograms (kg)metric tons (mt)metric tons (mt)kilocalories (kcal)

Celsius degrees

square feetsquare milesacres

0.264235.310.0008110

0.000035270.035272.205

2205.01.1023.968

1.8(C6) + 32

gallonscubic feetacre-feet

ouncesouncespoundspoundsshort tonsBTU

Fahrenheit degrees

U.S. Customary to Metric

inchesinchesfeet (ft)fathomsmiles (mi)nautical miles (nmi)

square feet (ft')acressquare miles (mi 2 )

gallons (gal)cubic feet (ftacre-feet

ounces (oz)pounds (lb)short tons (ton)BTU

Fahrenheit degrees

25.402.540.30481.8291.6091.852

0.09290.40472.590

3.7850.02831

1233.0

mril I imeterscentimetersmetersmeterski 1 ometerskilometers

square metershectaressquare kilometers

literscubic meters.cubic meters

gramskilogramsmetric tonskilocalories

Celsius degrees

28.350.45360. 90720. 2520

0.5556(F° - 32)

CONTENTS

Page

CONVERSION TABLE ............................ ................. iPREFACE. . ..................................................... ivACKNOWLEDGMENTS . .. ................... ............... ......... v

NOMENCLATURE/TAXONOMY/RANGE ..................... ............... 1MORPHOLOGY/IDENTIFICATION AIDS . .............. ..................... IREASON FOR INCLUSION IN SERIES ..................... ............. 3LIFE HISTORY ................. ..... ......................... 3

Reproductive Physiology/Strategy ............. .................... 3Spawning-General ...... ........... ...................... 4Spawning Periodicity .................................. 4Spawning Behavior ................................................. 5Dissolved Oxygen Depletion (Spawning) ...... . ..... ............ 5Eggs 5Egs....................................... 5Yolk-Sac Larvae. 6.............................6Larvae.................................................. 6Juveniles/Adults . ... ..... . ... .......... ................ 7

GROWTH CHARACTERISTICS... . . . . . . . . . . . . . ....... .......... 8THE FISHERY .................... 9

Commercial and Recreational Fisheries. . ....... ............... 9Population Dynamics .... ................... ....................... 9

ECOLOGICAL ROLE ..................... .................. ........ 9Food Habits/Feeding Behavior ........ . .......... ......... I ..... 9Predators ........................................ .......... 10Competitors .......................... ................ ..... 10Role as Estuarine Biomass Exporter ........... .... ............... 10

ENVIRONMENTAL REQUIREMENTS ............... ........................ 10Temperature ..................... .............................. 10Salinity ................ ................................ . I.11

LITERATURE CITED .................. ............................. 12

iii

PREFACE

This species profile is one of a series on coastal aquatic organisms,principally 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 environmental require-ments 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, life 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:

Information Transfer SpecialistNational Coastal Ecosystems TeamU.S. Fish and Wildlife ServiceNASA-Slidell Computer Complex1010 Gause BoulevardSlidell, LA 70458

or

U.S. Army Engineer Waterways Experiment StationAttention: WESERPost Office Box 631Vicksburg, MS 39180

This series should be referenced as follows:

U.S. Fish and Wildlife Service. 1983. Species profiles: life histories andenvironmental requirements of coastal fishes and invertebrates. U.S. Fishand 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 historiesand environmental requirements of coastal fishes and invertebrates (Mid-Atlantic) -- Atlantic silverside. U.S. Fish and Wildlife Service,Division of Biological Services, FWS/OBS-82/11.10. U.S. Army Corps ofEngineers, TR EL-82-4. 15 pp.

iv

ACKNOWLEDGMENTS

We are grateful for the review by Dr. David Conover, State University of New Yorkat Stony Brook, Long Island.

V

Figure 1. Atlantic silverside.

ATLANTIC SILVERSIDE

NOMENCLATURE/TAXONOMY/RANGE

Scientific name . ... Menidia menidiaPreferred comrion name . Atlantic sil-

verside (Figure 1).Other common names.. Spearing, sper-

Iing, green smelt, sand smelt, whitebait, capelin, shiner (Bigelow andSchroeder 1953).

Class ................ .OsteichthyesOrder . ...... . .Atheriniformes

Family .... .......... .. Atherinidae

Geographical range: Atlantic coast ofNorth America, from just north of47 degrees north latitude, in New

Brunswick, Nova Scotia, and theMagdalen Islands (Gosline 1948),south to Volusia County, Florida(Leim and Scott 1966). Wide-spread and abundant in coastalwaters and tributaries of theentire area (Massmann 1954; Rob-bins 1969) (see Figure 2 for amap of the mid-Atlantic distribu-tion of Atlantic silverside).

MORPHOLOGY/IDENTIFICATION AIDS

The following information wastaken from summaries in Martin andDrewry (1978), where a detailedmorphological description is available.

I

N.Y.

-

I,

N.J.i

PHILADELPHIA ATLANTIC OCEAN

MILES

0 50 100

0 50 100

KILOMETERS

CHESAPEAKEBA Y * Offshore distribution 0

W Area of high abundancein winter

S Area of high abundancein spring, summer,and fall

IARLE,SoUND

/L. ' O'kCAPE HA TTERAS

Figure 2. Mid-Atlantic distribution of the Atlantic silverside. The offshoredistribution boundary is representative of the majority of Atlantic silversidepopulations; however, National Marine Fisheries Service (NMFS) trawl surveyshave reported Atlantic silversides offshore to 180 km (112 mi) in spring/sum-mer and to 150 km (93 mi) in winter (Conover and Murawski 1982).

2

Dorsal spines 3-7 (mean 4.6),dorsal rays 7-11 (mean 8.6), analspines 1 , anal rays 19-29 (mean23.6). Lateral line scales betweenpectoral insertion and caudal fin 34-47(mean 40.7).

Body elongate, slender, roundedto dorsally depressed. Head triangu-lar, dorsally flattened; mouth terminaland slightly superior, maxillary notextending to front of eye. Scalescycloid with entire margins, wellimbricated.

.. Color: Dorsally translucent greento greenish-yellow; laterally silver,with well defined, longitudinal, metal-lically lustered, silver-colored stripe,edged above by dark line; ventrallywhite. Dorsal and caudal fin rays uni-formly spotted, and caudal fin usuallytinged with yellow.

REASON FOR INCLUSION IN SERIES

The Atlantic silverside is animportant forage fish (Merriman 1941;Bayliff 1950; Bigelow and Schroeder1953), reaching high abundance in theshore-zone of salt marshes, estuariesand tidal creeks. This species is oftenthe most ab.undant fish encountered inthese areas (Mulkana 1966; Richardsand Castagna 1970; Briggs 1975;Anderjson et al. 1977; Hillman et al.1977).'

The importance of Atlantic silver-*sides as forage for such piscivores asstriped bass (Morone saxatilis),Atlantic mackerel (Scomber scombrus),and bluefish (Pomatomus saltatrix) hasbeen well documented (Bayliff 1950.;Bigelow and Schroeder 1953; Schaefer1970). Presumably then, the Atlanticsilverside should be a key member ofthe estuarine food web, but untilrecently, little study . has beendevoted to its life history,

particularly -environmental require-ments (Conover and Ross 1982).

LIFE HISTORY

Reproductive Physiology/Strategy

Atlantic silversides are hetero-

sexual; however, an. unusual mecha-

nism of sex determination in thisspecies has been identified. Adultgender is apparently controlled byinteraction of female parent genotype

with water temperature regime duringa specific and critical period of larvaldevelopment (see LIFE HISTORY--Lar-vae section) (Conover and Kynard1981). Reproductive mode varies frompolygamy (Middaugh et al. 1981) toextensive promiscuity (Conover 1982).

Both sexes of the Atlantic silver-side mature by age 1. Although2-year-old specimens have beenreported (Bayliff 1950; Conover andR6ss 1982), apparently most adults dieafter completion of their first spawn-ing (perhaps because of physiologicalexhaustion) (Conover and Ross 1982),or are lost to other causes of mortal-

ity before they reach age 2. InEssex Bay, Massachusetts,. 2-year-old fish constituted 0.2% and 1.0%,respectively, of the 1977 and 1978spawning populations. Both males andfemales were represented by2-year-old individuals (Conover andRoss 1982). Females are larger andheavier than males of the same age(Conover 1982), a fact that may berelated to the unusual mechanism ofsex determination discussed in theLIFE HISTORY -Larvae section.

Little is known concerning fre-quency of spawning within a seasonfor an individual silverside. A fre-quency of four or five times perfemale per season was reported inConover (1979). In laboratory studiesof spawning activities of female Atlan-tic silversides in 85-1 aquaria,

3

individual females spawned up to 20separate times in a season (Conover1982). The applicability of thisspawning frequency to field environ-ments is -unknown, since (1) ripefemales were placed in test tanksindividually, rather than in largeschools as in natural environments;(2) spawning periodicity of an indi-vidual female was every 1 to 3 days,not coinciding with normal lunarcycles or observed natural spawningperiodicity; and (3) no "tide-like"influences were applied in the labora-tory tests.

Fecundity of Atlantic silversidesranged from 4,725 to 13,525 totaleggs. The average number of eggsactually spawned in a season was4,500 to 5,000 per female. It wasnoted that these eggs were probablyreleased in four or five separatespawning events per female per year(Conover 1979). A much lower fe-cundity estimate, from earlier studies,was an average of 500 eggs (Hilde-brand 1922) and a range up to 1,400eggs (Kendall 1902).

Spawning-General

Atlantic silversides spawn in theintertidal zone of nearly all majorestuaries and tributaries within, theirgeographic range (Hildebrand 1922;Wang 1974). Spawning areas are sea-ward of locations used by Menidiaberyllina (inland silverside), a closelyrelated species (Smith 19.71). Themajor spawning season of Atlantic sil-versides in the mid-Atlantic regionextends from late March through June(Nichols 1908; Hildebrand 1922; Mid-daugh 1981). Ripe females have beencollected through July in Massachu-setts (Kuntz and Radcliffe 1917; Wil-liams and Shaw 1971) and in Chesa-peake Bay (Bayliff 1950; Rasin 1976),at water temperatures between 130 and30*C (550 and 860F) (Middaugh andLempesis 1976). Spawning began attemperatures between .160 and 200 C(610 and 680 F) in South Carolina,

over a 3-year-period (Middaugh 1981).Initiation of spawning is probablydetermined by water temperature,photoperiod, or, both (Middaugh andLempesis 1976), in conjunction withhigh tide and appropriate lunar phaseduring the spring months (Middaugh1981; Conover 1982).

Spawninq Periodicitv

Menidia menidia is one of over 50fish species known to have lunar-related spawning cycles (.Johannes 1978;Conover 1982). Spawning occursstrictly during daylight hours in largeschools, and coincides with high tide(Middaugh 1981). The first spawningactivity usually occurs at a new orfull moon in early spring, and is fol-lowed by spawning peaks at approxi-mately 14- (Conover 1982) or 15-day(Middaugh 1981) intervals. Somespawning activity was observed ondays other than those of new or fullmoon (Middaugh 1981), but up to 90tof the spawning within each 14- to15-day stratum occurred over 1-(Conover 1982) to 3-day (Middaugh1981) periods. Some differences inspawning periodicity between SouthCarolina and Massachusetts populationsof, Atlantic silverside have beenreported. Conover (1982) concludedthat spawning periodicity in Massa-chusetts was highly correlated to thelunar phase, and that spawning inten-sity was dependent on relative heightof a given high tide. In contrast,Middaugh (1981) found that the great-est correlation in South Carolina pop-ulations was between spawning perio-dicity and the coincidental occurrenceof sunrise and high tide, approxi-mately every 15 days. Days of hightide at sunrise also coincided fairlyclosely with new and full lunar phasesduring spring months. Regardless,the periodicity-lunar phase correlationwas not as high as the periodicity-sunrise and high tide correlation inthe South Carolina population. Addi-tionally, relative height of the hightide was not correlated with spawning

4

intensity (Middaugh 1981). Duringspring high tides, the greatestspawning intensity was observed atthe slack (Middaugh 1981) or ebbing(Conover 1982) stages. It is apparentfrom studies of Atlantic silversidespawning periodicity that specific.mechanisms and adaptive significanceof lunar-related spawning cycles arepoorly understood (Conover 1982).

Spawning Behavior

Middaugh et al. (1981) described.spawning behavior of Atlantic silver-sides in South Carolina. One-half to 1hour prior to a spawn, a single largeschool or several smaller schools ofadults appeared 10 to 30 m (33 to 98ft) offshore, adjacent to the eventualspawning site. Schools swam parallelto shore, gradually moving shorewardwith the flood stage until the leadingedge of the school was 2 to 3 m (6 to10 ft) from shore. Positions in relationto shore and swimming speed of theschool were maintained until justbefore peak high tide, when severalindividuals moved suddenly intoflooded shoreline vegetation, followedby the remainder of the spawningschool. Eggs were released as afemale crossed the axis of a potentialattachment substrate such as a cord-grass plant. One to several males fol-lowed closely and deposited milt. Sev-eral variations on this generalbehavioral pattern were described inMiddaugh et al. (1981) and Conover(1982), including spawning in aban-doned fiddler crab (Uca pugilator)burrows.

Dissolved Oxygen Depletion (Spawning)

Middaugh (1981) and Middaugh etal. (1981) found that extremely highspawning densities, commonlyobserved during peak Atlantic silver-side spawning episodes, temporarilydepleted dissolved oxygen concentra-tions in the immediate area of the mostintense spawning activity. Dissolvedoxygen isopleths coincided closely with

density gradients of spawning fishwithin a school. In an unusuallyintense spawning event on 30 April1976, dissolved oxygen dropped from6 mg/I to 0.7 mg/I in the center ofthe spawning mass.

An interesting consequence ofthis dissolved oxygen depletion wasreported (Middaugh 1981). Predatorssuch as small bluefish and spottedseatrout (Cynoscion nebulosus), sur-rounding spawning schools of Atlanticsilversides, were unable to penetratepast the 4.0 mg/I and 2.5 mg/I dis-solved oxygen isopleths, respectively.This apparently limited or preventedpredation on the heaviest concentra-tions of Atlantic silversides during thetime of peak spawning (Middaugh1981). The oxygen depletion in combi-nation with the energy drain, associ-ated with spawning appeared to affectthe spent silversides (Middaugh 1981).Spent fish from intense spawningevents were observed offshore fromspawning beds in tight but nonschool-ing aggregations, and appeared to bestuporous and in a state of physiolog-ical recovery. These stuporous aggre-gations could be approached by man,and presumably by predators, withrelative ease.

Eggs

Eggs of the Atlantic silversidegenerally range from 0.9 to 1.2 mm 1 indiameter (Wang 1974; Middaugh 1981),though diameters up to 1.5 mm havebeen reported (Tracy 1910; Leim andScott 1966). Eggs are transparent,yellow to green, and have 5 to 12large oil globules and numerous smallglobules (Kuntz - and Radcliffe 1917;Hildebrand 1922). Eggs are demersal,adhesive, and found in shallow watersof estuarine intertidal zones (Kuntzand Radcliffe 1917; Hildebrand 1922;Middaugh 1981).

Substrates for egg attachment aresubmerged vegetation (Bayliff 1950),particularly eelgrass (Middaugh 1981),

'25.4 mm = 1 inch.

5

cordgrass (Middaugh et al. 1981), andfilamentous algae (Conover 1982).Sand (Wang 1974) and beach trash.(Nichols 1908) may also harborattached" eggs. Studies in Salem Har-bor, Massachusetts, indicated that eggattachment substrates there were morespecific than those described for othersilverside populations. Only algal matsof the filamentous brown algae Pilay-ella littoralis and Entermorpha spp.were used, even though these algaewere growing among various aquaticvascular plants such as Spartinaalterniflora (Conover 1982).

Egg attachment is reinforced byseveral filaments (Hildebrand 1922;Middaugh 1981; Conover 1982) origi-nating from a specific area of thechorion (Kuntz and Radcliffe 1917;Wang 1974), which uncoil upon ovipo-sition (Ryder 1883; Hildebrand 1922).Filaments are usually from five (Mid-daugh 1981) to eight (Ryder 1883)times the egg diameter in length.Eggs may also adhere to each other inclusters (Hildebrand 1922; Leim andScott 1966).

Incubation time for Atlantic sil-verside eggs was 3 days at 30*C (860F), 5 days at 25*C (77*F), 10 days at200C (68°F), 15 days at 18'C (64°F),and 27 days at 15'C (59"F) (Costelloet al. .1957; Austin et al. 1975). Anequation for predicting incubation timefrom water temperature, calculatedfrom data in Austin et al. (1975) byMartin and Drewry.(1978), is:

log(t) = 2.2672 - 0.0623(T)

where t = time in days and T = incu-bation temperature in degrees C.

Middaugh (1981) found that maxi-mum egg abundance in South Carolinawaters occurred at depths of 1.6 to2.2 m (5.3 to 7.2 ft) below the meanlow water (low tide) line. Embryoviability was also highest in thisdepth range, though a statisticallysignificant correlation between embryo

viability and depth of embryo locationwas not indicated.

Yolk-Sac Larvae

Atlantic silverside yolk-sac larvaerange from 3.8 to 5.0 mm total length(TL) at hatching (Wang 1974). Theproportion of the original yolk-sacremaining at hatching depends onincubation temperature; a definedyolk-sac is absent when eggs areincubated at 250 C (770 F) or less(Bayliff 1950; Austin et al. 1975).Remaining yolk is absorbed 2 (Mid-daugh and Lempesis 1976) to 5 (Rubi-noff 1958) days after hatching. Yolk-sac larvae are transparent withpigmented eyes at hatching (Hildebrand1922; Middaugh and Lempesis 1976).Middaugh (1981) found that larvalhatching occurred primarily at nightduring high tides, and suggested thatdecreased predation may be a benefitof nocturnal emergence.

Larvae

Atlantic silverside larvae rangefrom 5.5 to 15.0 mm TL (Wang 1974).Both yolk-sac larvae, and larvae havea notably forward anus, rarely far-ther behind the snout than one-fourthof the total larval length (Martin andDrewry 1978). Size at transformationto the juvenile stage is not estab-lished, but transformation occursbefore 20 mm TL (Wang 1974) and iscomplete when the anus has migratedback along the ventral surface of thebody to the approximate midpoint(Hildebrand 1922).

An unusual method of sex deter-mination during the larval stage ofAtlantic silversides was demonstratedin a series of laboratory experimentsby Conover and Kynard (1981). Lar-vae subjected to a "cold fluctuating"temperature regime similar to tempera-tures experienced by larvae in May,between 110 and 191C (52' and 66*F),produced more females than males. . Incontrast, a "warm fluctuating"

6

temperature regime similar to tempera-tures experienced by larvae in July,between 170 and 250C (630 and 77 0 F),produced significantly more males thanfemales. Further, it was determinedthat the mechanism of sex determina-tion was not by selective egg or larvalmortality, but rather the temperatureregime experienced by larvae during acritical period, which was between 32and 46 days after hatching. The watertemperature regime experienced bylarvae at that stage of developmentdetermined whether mostly males orfemales developed (Conover andKynard 1981). These laboratory find-ings were corroborated by examinationof sex ratios in natural populations(Essex Bay, Massachusetts) over time(Conover 1982).

Dovel (1971) reported that Atlan-tic silverside larvae were presentthroughout low salinity areas of upperChesapeake Bay, from April throughDecember. Larvae were most abundantin surface waters (< 3 m, < 10 ft) andat salinities of 8 or 9 ppt. Some lar-vae were found in waters where salin-ities ranged from 1 to 14 ppt andwater temperatures from 12' to 300C(540 to 86%F). In the Mystic RiverEstuary, Connecticut, Atlantic silver-side larvae were found primarily inupper estuarine zones and marshes,where the salinity profile ranged from2 ppt at the surface to 14 ppt at 2 m(6 ft) depth. All larvae were collectedin May and June and ranged from 5.2to 7.5 mm TL (Pearcy and Richards.1962).

Juveniles/Adults

Juvenile Atlantic silversidesrange in size from about 20 mm TL(Wang 1974) *to approximately 91 mmTL (males) or-98 mm TL (females)(Leim and Scott 1966; Conover andRoss 1982). The juvenile stage lastsfrom the completion of anal ventmigration along the ventral midline(Martin and Drewry 1978) to cessationof growth in late fall (Conover 1982).

Smaller juveniles select habitats overvegetated substrates more often thanthe sand and gravel substratesselected by larger juveniles and adults(Briggs and O'Conner 1971).

Juvenile and adult Atlantic sil-versides inhabit intertidal creeks,marshes, and shore zones of bays andestuaries in spring, summer, and fall(Hildebrand and Schroeder 1928;Bigelow and Schroeder 1953). Tempo-ral variation in local abundance,probably due in part to fish move-ments in relation to tidal patterns,has been reported (Merriman 1947;Shenker and Dean 1979; Conover1982; Conover and Ross 1982). Dur-ing spring, summer, and fall, Atlanticsilversides have often been reported,as the most abundant species in marshand estuarine habitats (Pearcy andRichards 1962; Mulkana 1966; Richardsand Castagna 1970; Briggs 1975;Anderson et al. 1977), yet they maybe entirely absent from the same areasduring winter (Bayliff 1950; Hoff andIbara 1977; Conover 1982; Conoverand Ross 1982).

Geographic variability exists .with

the winter ecology and habitat ofadult Atlantic silversides (Conoverand. Murawski 1982). In populationsfrom Chesapeake Bay northward,Atlantic silversides are rare or absentfrom shore zones or shallow waters inmidwinter (Bayliff 1950; Hoff andIbara 1977; Conover and Ross 1982).Richards and Castagna - (1970)reported that adult Atlantic silversideswere captured in midwinter with bot-tom trawls in deepwater areas ofChesapeake Bay and estuarine chan-nels along eastern Virginia. Wintercatches of adults out to 15 km (913mi) (Clark et al. 1969; Fahay 1975)and 170 km (105.6 mi) (Conover andMurawski 1982) offshore have beenreported. In South Carolina tidalcreeks, however, adults were presentin high abundance throughout winter(Cain and Dean 1976; Shenker andDean 1979).

7

National Marine Fisheries Service(NMFS) survey data, collected withbottom trawls from Cape Cod, Massa-chusetts, to Cape Hatteras, NorthCarolina, was summarized by Conoverand Murawski (1982). From 1972 to1979 (data pooled), percent frequencyof occurrence (number of stationscaptured divided by number of sta-tions surveyed) of Atlantic silversidesin depth strata, between 5 and 27 m(16 and 89 ft), peaked in January(34.3%). Atlantic silversides alsooccurred in March (21.4%), April(9.6'o), and November (4.9%). Depthstrata from 5 to 27 m were not sam-pled in February. At depth stratabetween 27 and 366 m (89 and 1,200ft) (1963 to 1979, data pooled), per-cent frequency of occurrence peakedin F'ebruary (11.2%), and dropped offin March (4.3%) and April (1.5%). Themajority (86%) of all Atlantic silver-sides captured in the' NMFS surveyswere at depths less than 50 m (164 ft)and water temperatures between 2'and 60 C (360 and 430F) (Conover andMurawski 1982).

Comparison of winter catch ratesduring different times of the dayindicated that overwintering Atlanticsilversides may migrate vertically inthe water column during twilight peri-ods. Consistently higher numbers ofsilversides were captured during theday with bottom trawls than at nightin the same overwintering areas (Con-over and Murawski 1982).

Biochemical characteristics(through electrophoresis) of Atlanticsilverside stocks (Morgan and Ulanow-icz 1976) and the genus Menidia(Johnson 1975) have been described.The applicability of such informationfor separation of stocks and apparentsubspecies of Menidia menidia (M. m.menidia, southern subspecies, and M.m. notata, northern subspecies) isdiscussed in Morgan and Ulanowicz(1976).

GROWTH CHARACTERISTICS

Growth of young-of-the-yearAtlantic silversides from hatching tomid-autumn was 10-15 mm/month inLong Island Sound (Austin et al.1973), 7-14 mm/month in a RhodeIsland estuary (Mulkana 1966), and 20mm/month in Essex Bay, Massachu-setts (Conover and Ross 1982).Young-of-the-year males attained 91.5mm and 3.9 g by November in EssexBay,, and females attained 98.0 mmand 4.8 g (Conover and Ross 1982).Growth of Atlantic silversides virtuallyceases between November and March,at least in areas where winter offshoremigrations occur (Bayliff 1950;Bigelow and Schroeder 1953; Conover1982; Conover and Ross 1982).

Condition factor of young-of-the-year Atlantic silversides in EssexBay, Massachusetts, dropped signifi-cantly. between September and Novem-ber for the large 1976 year class,but not for the less abundant. 1977year class (Conover and Ross 1982).For both year classes, the conditionfactor r-mained stable through winter,increasing in April and May of thefollowing spring. Conover and Ross(1982) suggested that the 1976 yearclass may haVe exceeded the carryingcapacity of the Essex Bay nurseryarea, resulting in the observedreduction in condition during latestages of the growing season (Octoberand November).

G rowth rates of age 11 maleAtlantic silversides in Essex Bayaveraged 5.8 mm/month and 1.1g/month over the period 6 May to 5November. Females grew 5.5 mm/monthand 1.4 g/month over the sameperiod. By 5 November, mean lengthsand weights of female Atlantic silver-sides exceeded values for males by 10mm and 2.9 g (Conover and Ross1982).

8

THE FISHERY

Commercial and. Recreational Fisheries

Commercial or recreational fisher-ies *for Atlantic, silversides are notdocumented. The authors haveobserved a small and scattered com-mercial bait fishery for Atlantic sil-versides using minnow traps or smallseines. Such localized bait fisheriesprobably have little if any impact onAtlantic silverside populations.Population Dynamics

In general, the Atlantic silversideis a short-lived species. Two-year-oldfish have been reported (Bayliff 1950;Conover and Ross 1982), but themajority of estuarine populations ofAtlantic silversides in spring, sum-mer, and fall are juveniles (age 0+)and age 1 adults (Conover andMurawski 1982).

Abundance of the 1977 year classof silverside juveniles in Essex Bay,Massachusetts, in late October andearly November (data pooled) was.ý (95 - fi-estimated at 1.88 1.16/m (95 conf-dence limits). Mean biomass of juve-niles peaked in late October and earlyNovember at 7.8 ± 2.8 9/m 2 Adultdensities on spawning grounds thenext spring (1978) were estimated at0.009 ± 0:002/m2 , indicating a totaloverwintering mortality rate of 99%(Conover and Ross 1982). Conoverand Ross (1982) examined Atlantic sil-*verside mortality estimates from othercoastal areas of Massachusetts andfound that overwintering mortalityaveraged 97%0 north of Cape Cod and88% south and west of Cape Cod. Sim-ilarly high overwintering mortality wasreported by Warfel and Merriman(1944) in Connecticut, Bayliff (1950)in Chesapeake Bay, and Austin et al.(1973) in New York.

Conover and Ross (1982) alsofound that overwintering mortality ofAtlantic silversides was selective

against larger fish, and total mortalitywas negatively related to mean sizeand condition of the juvenile yearclass prior to winter migration. Theysuggested that, since densities ofadults returning the following springwere similar regardless of the fallpopulation size, a density compensa-tory mechanism of overwintering mor-tality may occur in Atlantic silversidepopulations.

Conover (1982) demonstrated thatsex ratios of Atlantic silversides inEssex Bay, Massachusetts, fluctuatedseasonally, partly because of theunusual mechanism of sex determina-tion described for this species (Con-over and Kynard 1981) (see LIFE,HISTORY-- Larvae section). Sex rat-ios in July and August consistentlyfavored females, while sex ratios inSeptember (year-class recruitmentcomplete), October, and Novemberfavored males. Sex. ratios on thespawning grounds the following springeither favored, females (1978) or werenot significantly different from 1:1(1976, 1977).

ECOLOGICAL ROLE

Food Habits/Feeding Behavior

Information about larval foodhabits, feeding behavior, and dailyration is not available. Juvenile andadult Atlantic silversides are oppor-tunistic omnivores. Food items con-sumed include copepods, mysids,amphipods, cladocerans, fish eggs,squid, worms, molluscan larvae,insects, algae, diatoms, and detritus(Bigelow and Schroeder 1953; Leimand Scott 1966; Thomson et al. 1971).

Atlantic silversides feed. in largeschools, often following the tidal ebband flow along feeding areas. Commonfeeding areas include gravel and sand

9

bars, open beaches, tidal creeks,river mouths and flooded zones ofmarsh vegetation (Bayliff 1950; Bige-low and Schroeder 1953). Informationabout feeding periodicity is not avail-able.

In laboratory tests, unfed larvaeand larvae fed for the first time onday 4 all died by day 6. Survival oflarvae fed at the end of day 2 variedwith salinity. At 20 ppt, all larvaewere dead by day 8, while at 30 ppt,40' survived through day 14 (Mid-duagh and Lempesis 1976).

Predators

Atlantic silversides are importantforage for such gamefish as stripedbass, Atlantic mackerel, and bluefish.(Bayliff 1950; Bigelow and Schroeder1953; Schaefer 1970). Other fishspecies, egrets, terns, gulls, cormo-rants, and blue crabs (Callinectessapidus) also prey on spawningschools of Atlantic silversides (Mid-daugh 1981).. Blue crabs, ruddy turn-stones (Arenaria interpres morinella),semipalmated sandpipers (Ereunetespusillus), and in particular, mummi-chogs (Fundulus heteroclitus), mayprey on eggs and larvae of Atlanticsilversides (Middaugh 1981; Conover1982).

Competitors

Definitive studies of competitiveinteractions between Atlantic silver-sides and other species are lacking.Some competition with the closelyrelated inland silverside (Menidiaberyllina) may occur, although thesetwo atherinids appear to be spatiallyseparated in many areas. The Atlanticsilverside generally selects habitatsmore seaward than those of the inlandsilverside (Robbins 1969).

Role as Estuarine Biomass Exporter

silversides migrate to offshore watersduring late fall. Numbers of age Iadults returning the following springindicated very high overwinteringmortality (99%). Few if any age I fishmake it to age 2; most age 1 fish dieafter spawning or during their secondwinter of life. This essentially annuallife cycle, with high mortality off-shore, suggests that Atlantic silver-sides are important exporters of sec-ondary production and biomass frommarsh and estuarine systems to off-shore areas (Conover and Murawski1982).

ENVIRONMENTAL REQUIREMENTS

Temperature

Eggs of Atlantic silverside toler-ated water temperatures as low as 15'C (590 F), but larvae that hatcheddied within 24 hr unless warmer waterwas located (Austin et al. 1975).Temperatures as high as 30'C (860F)were also tolerated by eggs. Visibleyolk was present upon hatching in 20%of the larvae reared at 30'C, but wasabsent in larvae hatched at 25'C (770F) or less (Austin et al. 1975).Optimum temperatures for hatching of

* eggs have not been determined.

Thermal shock of an 8'C (14'F)increase produced no mortality ofAtlantic silverside larvae reared at 170and 20'C (63' and 68°F), 19' mortal-ity at 25'C (77'F), and 11% mortalityat 30'C (86'F) Thermal shock of a14' C (25' F) increase produced . 3%mortality of larvae reared at 17'C (630F), 0% at 20-C (680F), and 1009% at256and 300 C (770 and 86' F) (Austin etal. 1975). Austin et al. (1975) con-cluded that, since Atlantic silversidelarvae would be present in LongIsland Sound at seasonal temperaturesbetween 15' and 20'C (59' and 68'F),the larval population would experienceminimal stress from nuclear power-plant development on Long Island.

Conover and Murawski (1982)demonstrated that age 0* Atlantic

10

Juvenile Atlantic silversides tol-erated water temperatures between 3Tand 31'C (370 and880F),and preferreda temperature range of 18' "to 250C (640 to 77°F) in upper ChesapeakeBay, during summer and fall (Dovel1971). Juveniles and adults accli-mated to 6VC (43'F) and 8'C (46'F),however, preferred water tempera-tures of 150C (59' F) (Meldrim andGift 1971). In general, avoidancebehavior of juveniles and adults wasobserved when test temperatures were110 to 14°C (200 to 25'F) higher thanthe acclimation temperature' (Meldrimand Gift 1971). Pearce (1969) reportedan upper lethal temperature of 32.00C(900 F) for Atlantic silversides col-lected from the Cape Cod Canal, Mas-sachusetts. Critical thermal maxima(defined as the temperature at whichopercular movements ceased for 30seconds) for Atlantic silversides col-lected from the Patuxent River,Maryland, were 30.5'C (87 0 F) and33.80C (93'F) for acclimation tempera-tures of 50C (41'F) and 15'C (599F),respectively (Hall et al. 1982).Atlantic silversides exposed to threedifferent fluctuating temperatureregimes, between 5 'C and 15 0 C,exhibited critical thermal maximaintermediate to the above values (Hallet al. 1982). Lower and upper 48-hrmedian tolerance limits (TLM, thetemperature at which 50%0 of test fish

died by 48 hr) were determined byHoff and Westman (1966) for a rangeof acclimation temperatures. Thelower TLM values for acclimationtemperatures of 70, 14", 21', and 280C (450, 570, 700, and 82°F)were 1.5'20, 50, and 9.5'C (35', 36", 41',

-aod 49'F), respectively. Upper TLMvalues for the same four acclimationtemperatures were 220, 260, 300, and320C (720, 790, 860, and 90'F),respectively (Hoff and Westman 1966).

Salinity

In laborat6ry tests, hatching wasdelayed 18 hr at 20 ppt salinity and42 hr at 10 ppt, compared to hatchingtime at 30 ppt (incubation temperaturewas 21.1 0C or 70 0 F). Percentagehatch was also reduced at salinitiesbelow 30 ppt, and optimum salinity forhatching was 30 ppt. Survival of lar-vae through 14 days was approxi-mately 77%0 at 30 ppt compared to only23% at 20 ppt. Growth rate of larvaethrough day 14 was lower at 20 pptcompared to 30 ppt (Middaugh andLempesis 1976). Juvenile and adultAtlantic silversides tolerated salinitiesfrom freshwater (Tagatz and Dudley1961; Tagatz 1967) to 37.8 ppt(Tagatz and Dudley 1961). Juvenileswere captured from upper ChesapeakeBay in salinities from 1 to 14 ppt, butpreferred 7 to 8 ppt (Dovel 1971).

11

LITERATURE CITED

Anderson, W. D., J. K. Dias, D. M.Cupka, and N. A. Chamerlain.1977. The macrofauna of thesurf zone off Folly Beach, SouthCarolina. NOAA Tech. Rep.NMFS SSRF-704. 23 pp.

Austin, H. M., J. Dickinson, and C.R. Hickey. 1973. An ecologicalstudy of the ichthyofauna at theNorthport Power Station, LongIsland, New York. Publ. LongIsland Lighting Co., Hicksville,N. Y. 248 pp.

Austin, H. M., A. D. Sosnow, and C.R. Hickey. 1975. The effects oftemperature on the developmentand survival of the eggs and lar-vae of the Atlantic silverside.Trans. Am. Fish. Soc. 104:762-765.

Bayliff, W. H. 1950. The life historyof the silverside, Menidia meni-dia. Chesapeake Biol. Lab. Publ.90. 27 pp.

Bigelow, H. B., and W. C. Schroe-der. 1953. Fishes of the Gulf ofMaine. U. S. Fish Wildl. Serv.Fish. Bull. 53. 577 pp.

Briggs, P. T. 1975. Shore-zone fishesof the vicinity of Fire IslandInlet, Great South Bay, NewYork. N. Y. Fish Game J. 22:1-7.

Briggs, P. T., and J. S. O'Conner.1971. Comparison of shore-zonefishes over naturally vegetatedand sand-filled bottoms in GreatSouth Bay. N. Y. Fish Game J.18: 15-41.

Cain, R. L., and J. M. Dean. 1976.Annual occurrence, abundanceand diversity of fish in a SouthCarolina intertidal creek. Mar.Biol. 36: 370-379.

Clark, J., W. G. Smith, A. W.Kendall, Jr., and M. P. Fahay.1969. Studies of estuarinedependence of Atlantic coastalfishes. U. S. Bur. Sport Fish.Wildl. Tech. Pap. 28. 132 pp.

Conover, D. 0. 1979. Density,growth, production, and fecun-dity of the Atlantic silverside,Menidia menidia, in a central NewEngland estuary. M.S. Thesis.University of Massachusetts,Amherst. 59 pp.

Conover, D. 0. 1982. Seasonal migra-tion, reproductive strategy, andenvironmental sex determination,and its adaptive significance inthe Atlantic silverside. Ph.D.Thesis. University of Massachu-setts, Amherst. 109 pp.

Conover, D. 0., and B. E. Kynard.1981. Environmental sex determi-nation: interaction of tempera-ture and genotype in a fish. Sci-ence 213: 577-579.

Conover, D. 0., and S. A. Murawski.1982. Offshore winter migrationof the Atlantic silverside. U.S.NatI. Mar. Fish. Serv. Fish. Bull.80: 145-150.

Conover, D. 0., and M. R. Ross.1982. Patterns in seasonal abun-dance, growth, and biomass ofthe Atlantic silverside in a NewEngland estuary. Estuaries 5:275-286.

Costello, D. P., M. E. Davidson, andA. Eggers. 1957. Methods forobtaining and handling marineeggs and embryos. Mar. Biol.Lab., Woods Hole, Mass. 247 pp.

Dovel, W. L. 1971. Fish eggs and lar-vae of the upper ChesapeakeBay. Univ. Md. Nat. Resour.

12

Inst. Spec. Rep. 4. 71 pp.

Fahay, M. P. 1975. An annotated listof larval and juvenile fishes cap-tured with surface-towed meternets in the South Atlantic Bightduring four RV Dolphin cruisesbetween May, 1967 and February,1973. NOAA Tech. Rep. NMFSSSRF-685. 39 pp.

Gosline, W. A. 1948. Speciation in thefishes of the genus Menidia. Evo-lution 2: 306-313.

Hall, L. W., Jr., D. T. Burton, andP. R. Abell. 1982. Thermalresponse of Atlantic silversides(Menidia menidia) acclimated toconstant and asymmetric fluctuat-ing temperatures. Arch. Hydro-biol. 94: 318-325.

Hildebrand, S. F. 1922. Notes onhabits and development of eggsand larvae of the silversides,Menidia menidia and M. beryllina.U. S. Bur. Fish. Bull. 38:113-1 20.

Hildebrand, S. F., and W. C.Schroeder. 1928. Fishes of Ches-apeake Bay. U. S. Bur. Fish.Bull. 43. 388 pp.

Hillman, R. E., N. W. Davis, and J.Wennemer. 1977. Abundance,diversity, and stability inshore-zone fish communities in anarea of Long Island Soundaffected by the thermal dischargeof a nuclear power station.Estuarine Coastal Mar. Sci. 5:355-381.

Hoff, J. G., and R. M. Ibara. 1977.Factors affecting the seasonalabundance, composition and di-versity of fishes in a southeasternNew England estuary. EstuarineCoastal Mar. Sci. 5: 665-678.

Hoff, J. G., and J. R. Westman.1966. The temperature tolerances

of three species of marine fishes.J. Mar. Res. 24(2): 131-139.

Johannes, R. E. 1978. Reproductivestrategies of coastal marine fishesin the tropics. Environ. Biol.Fishes 3: 65-84.

Johnson, M. S. 1975. Biochemical sys-tematics of the Atherinid genusMenidia. Copeia 1975: 662-691.

Kendall, W. C. 1902. Notes on thesilversides of the genus Menidiaof the east coast of the UnitedStates, with descriptions of twonew subspecies. Rep. U. S.Fish. Comm. (1901): 241-267.

Kuntz, A., and L. Radcliffe. 1917.Notes on the embryology and lar-val development of twelve teleos-tean fishes. U. S. Bur. Fish.Bull. 34: 407-429.

Leim, A. H., and W. B. Scott. 1966.Fishes of the Atlantic coast ofCanada. Fish. Res. Board Can.Bull. 155: 1-485.

Martin, F. D., and G. E. Drewry.1978. Development of fishes ofthe mid-Atlantic Bight, VolumeVI. U. S. Fish Wildl. Serv. Biol.Serv. Program FWS/OBS-78/12.416 pp.

Massmann, W. H. 1954. Marine fishesin fresh and brackish waters ofVirginia rivers. Ecology 35:75-78.

Meldrim, J. W., and J. J' Gift. 1971.Temperature preference, avoid-ance and shock experiments withestuarine fishes. Ichthyol. Assoc.Bull. 7. 75 pp.

Merriman, D. 1941. Studies on stripedbass of the Atlantic coast. U. S.Fish Wildl. Serv. Fish. Bull. 50:1-77.

13

Merriman, D. 1947. Notes on themidsummer ichthyofauna of aConnecticut beach at differenttide levels. Copeia 1947: 281-286.

Middaugh, D. P. 1981. Reproductiveecology and spawning periodicityof the Atlantic silverside. Copeia1981: 766-776.

Middaugh, D. P., and P. W. Lempe-sis. 1976. Laboratory spawningand rearing of a marine fish, thesilverside Menidia menidia meni-dia. Mar. Biol. 35: 295-300.

Middaugh, D. P., G. I. Scott, and J.M. Dean. 1981. Reproductivebehavior of the Atlantic silver-side. Environ. Biol. Fishes 6:269-276.

Morgan, R. P., II, and N. I. Ulanow-icz. 1976. The frequency of mus-cle protein polymorphism in Meni-dia menidia along the Atlanticcoast. Copeia 1976: 356-360.

Mulkana, M. S. 1966. The growth andfeeding habits of juvenile fishesin two Rhode Island estuaries.Gulf Res. Rep. 2: 97-168.

Nichols, J. T. 1908. A note on thesilverside. Am. Nat. 42: 731.

Pearce, J. B. 1969. Thermal additionand the benthos, Cape CodCanal. Chesapeake Sci. 10:227-233.

Pearcy, W. G., and S. W. Richards.1962. Distribution and ecology offishes of the Mystic River Estu-ary, Connecticut. Ecology 43:248-259.

Rasin, V. J. 1976. Spawning and lar-val fish in the Potomac Estuary.Pages 95-99 in The Potomac Estu-ary, trends and options. Proc.Symp. Md. Dep. Nat. Resour.,1975, Alexandria, Va.

Richards, C. E., and M. Castagna.1970. Marine fishes of Virginia'seastern shore (inlet and marsh,seaside waters). Chesapeake Sci.11: 235-248.

Robbins, T. W. 1969. A systematicstudy of the silversides. Ph.D.Thesis. Cornell University,Ithaca, N. Y. 281 pp.

Rubinoff, I. 1958. Raising the Atheri-nid fish, Menidia menidia, in thelaboratory. Copeia 1958: 146-147.

Ryder, J. A. 1883. On the threadbearing eggs of the silversides.U. S. Fish. Comm. Bull. 3:193-196.

Schaefer, R. H. 1970. Feeding habitsof striped bass from the surfwaters of Long Island. N. Y.Fish Game J. 17: 1-17.

Shenker, J. M., and J. M. Dean.1979. The utilization of an inter-tidal salt marsh creek by larvaland juvenile fishes: abundance,diversity and temporal variation.Estuaries 2(3): 154-163.

Smith, B. A. 1971. An ecologicalstudy of the Delaware River inthe vicinity of Artificial Island.Part V of The fish of four low-salinity tidal tributaries of theDelaware River Estuary.Ichthyol. Assoc. Rep. Publ.Serv. Electric and Gas Co.,Ithaca, N. Y. 291 pp.

Tagatz, M. E. 1967. Fishes of the St.Johns River, Florida. J. Fla.Acad. Sci. 30(1): 25-50.

Tagatz, M. E., and D. L. Dudley.1961. Seasonal occurrence ofmarine fishes in four shore habi-tats near Beaufort, North Caro-lina, 1957-1960. U. S. Fish Wildl.Serv. Spec. Sci. Rep. Fish. 390.19 pp.

14

Thomson, K. S., W. H. Weed III,and A. G. Taruski. 1971. Salt-water fishes of Connecticut.Conn. State Geol. Hist. Surv.Bull. 105. 165 pp.

Tracy, H. C. 1910. Annotated list ofthe fishes known to inhabit thewaters of Rhode Island. Annu.Rep. R. I. Comm. Inland Fish.40: 35-176.

Wang, J. C. S. 1974. Atherinidae---silversides. Pages 143-151 in A.J. Lippson and R. L. Moran,eds. Manual for identification of

early developmental stages offishes of the Potomac River Estu-ary. Md. Dep. Nat. Resour.Power' Plant Siting Program.PPSP-MP-13. 282 pp.

Warfel, H. E., and D. Merriman.1944. Studies on the marineresources of south New England.Bull. Bingham Oceanogr. Collect.Yale Univ. 9: 1-91.

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15

50272-101

REPORT DOCUMENTATION _. REPORT NO. 2.

PAGE FWS/OBS-82/1 .10* _

4. Title and Subtitle

Species Profiles: Life Histories and Environmental Requirementsof Coastal Fishes and Invertebrates (Mid-Atlantic) -- AtlanticSilverside

7. Author(s)

Clemon W. Fay, Richard J. Neves, Garland B. Pardue9. Performing Organization Name and Address

Department of Fisheries and Wildlife SciencesVirginia Polytechnic Institute and State UniversityBlacksburg, VA 24061

3. Recpient's Accession No.

5. Reort ite 986ao,•tober 1983

6.

S. Pedor--ing Organizationi Riept. N10.

10. Project/T..si/Work Unit No.

11. Contract(C) or Grant(G) No.

(C)

(G)

1Z. Sponsoring Organization Name and Address 13. Type of Report & Period Covered

National Coastal Ecosystems Team U.S. Army Corps of EngineersFish and Wildlife Service Waterways Experiment StationU.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 -ords)Species profiles are literature summaries of the taxonomy, morphology, range, life history,and environmental requirements of coastal aquatic species. They are prepared to assist inenvironmental impact assessment. The Atlantic silverside (Menidia menidia) is an importantlink in estuarine food webs as an opportunistic omnivore and as forage for large piscivoressuch as striped bass (Morone saxatilis) and bluefish (Pomatomus saltatrix). Many times theAtlantic silverside is the most abundant fish species encountered in estuaries and tribu-taries. They mature at age I and spawn in the intertidal zone of estuaries from March toJune in the mid-Atlantic region. Few 2-year-old fish are ever encountered, so the Atlanticsilverside is basically a short-lived species. Most spawning occurs at high tide duringnew or full moon phases. Eggs are adhesive and are found attached to submerged vegetation.Larvae, juveniles, and adults generally inhabit similar areas. Sex is determined in larvaldevelopment 32 to 46 days after hatching, and is a function of parental genotype and watertemperature regime during the critical period. Fisheries for this species are not documen-ted. Eggs can tolerate water temperatures between 15' and 30'C, and larvae need temperatureabove 150 C for survival. Larvae tolerate relatively acute temperature increases. Upperlethal temperatures for juveniles and adults range from 30.50 to 33.8 0 C, depending onacclimation temperature. Salinities of 20 ppt or lower significantly delay hatching andaffect larval survival. Juveniles and adults tolerate the full range of naturallyoccurring salinities (i.e., freshwater to at least 37.8 ppt).

17. Document Analysis a. Descriptors

EstuariesFishesGrowthFeeding

b. Identifiers/Open.Ended Terms

Atlantic silversideMenidia menidiaSalinity requirementsTemperature requirements

Life historySpawning

c. COSATI Field/Group

18. Availability Statement

Unl imited

19. Security Class (This Report) 21. No. of Pages

Unclassified 1520. Security Class (This Page) 22. Price

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