REFERENCECOP' 

Do Not Remove from the J-;bvrv 

U. - S. Fish and Wildlife "er.;: -2 m I 

FWSIOBS-82111.3 National ~IUS r>csr[ :I L: 1 CL;-C~-T 

February 1983 700 Cajun Dome Boule*far,3 

TR EL-82-4 

~afa~ette, Loui siona 70506 

Species Profiles: Life Histories and 

Environmental Requirements (Gulf of Mexico) 

ATLANTIC CROAKER 

Waterways Experiment Station 

Fish and Wildlife Service Coastal ~n~ineerin~ Research Center 

U.S. Department of the Interior U.S. Army Corps of Engineers 
FWS/OBS-82/11.3 

TR EL-82-4 

February 1983 

Species Profiles: Life Histories and 

Environmental Requi remen ts (Gul f of Mexico) 

ATLANTIC CROAKER 

Dennis R. Lassuy 

U.S. Fish and Wildlife Service 

National Coastal Ecosystems Team 

1010 Gause Boulevard 

Slidell, LA 70458 

Project Manager 

Larry Shanks 

Project Officer 

Norman Benson 

National Coastal Ecosystems Team 

U.S. Fish and Wildlife Service 

1010 Gause Boulevard 

Slidell, LA 70458 

This study was conducted 

in cooperation with 

U. S. Army Corps of Engineers 

Waterways Experiment Station and 

Coastal Engi neeri ng Research Center 

Performed for 

National Coastal Ecosystems 1-earn 

Division of Biological Services 

Fish and Wildlife Service 

U.S. Department of the Interior 

Washi ngton , DC 20240 
PREFACE 

T+i s series OF profi Ics about coastal aquatic species of commercial, 

sport, arld/or ecol~gicdl signi ficance i s being jointly developed and funded by 

the I1.S. Army Corps of Engineers and the 1J.S. Fish and Mildlife Service. It 

i s designed to provide coastal managers, engineers, and field hi 01 ogi sts wi th 

an introduction to the subiect species and a synopsis of the inforrnation 

necessary to relate expected changes (associated with coastal development) i n 

the ~hysicoche~nical characteri stics of estuaries to changes in these selected 

bi ologicdl populations. Each profi le includes brief sections on taxonomy and 

identification fol lo~led by a narrative of li fe hi story, environmental roqcrirernents, ecologicals role, and (where applicable) the fishery of the subject 

species. A three-rin3 binder is used for t+is series to facili tato additions 

as new profiles are prepared. 

Suggestions or questions regarding this report should be directed to: 

Information Transfer Special i st 

National Coastal Ecosys terns Team 

1J.S. Fish and Wildlife Service 

NASA-Sl idel 1 Computer Cornpl ex 

1010 Gause Boul evard 

Sl idell , LA 70458 

U.S. Army Engineer Waterways Experiment Station 

Attention: WESES 

Post Office Box 631, 

Vicksbu rg, F!S 39190 

11 .S. Army Coastal Engineering Research Center 

Kingman Building 

Fort Belvoir, VA 22060 

Thi s series should be referenced as fol lows : 

U.S. Fish and Wildlife Service. 1983. 5pecies profiles: life histories and 

environmental requirements. I1.S. Fish and Wi ldli fe Service, Di vi si on of 

Biological Services, FWS/OBS-82/11. U.S. Army Corps of Engineers, TR 

EL-82-4. 

Thi s profi le should be ci ted as fol lows : 

Lassuy, D.R. 1933. Species profiles: 1i fe hi stories and environmental 

requirements (Gulf of Flexico) -- Atlantic croaker. 1J.S. Fish and Wild1i fe Service, 3ivi sion of Biological Services. FivIS/ORS-82/11.3. U.S. 

Armny Corps of Engineers, T9 EL-82-4. 12 pp. 
Fig~re i. Atlantic croaker. 

ATLANTIC CROAKER 

Scientific name ... i . -- Micropogonias 

undulatus (Li nnaeus) 

PrTferred comrnon name .... Atlantic 

croaker (Figure 1) 

Other comc~on names ...... Croaker, 

crocus, hardhead, King Bi 1 ly, la 

corbi na 

Class .......... Osteichthyes 

Order ........... Perci fornies 

Farni ly .......... Sciaenidae 

64-72; Gr. 7 + 28-25; A.11, 7-8; Sc. 

depth 2.3-3.65. Body elonsate, compressed; back moderately elevated; head 

rather long; snout conical, projecting 

beyond the mouth in the adult and proportionately r~uch longer than in the 

very young, 2.85 to 3.75 ir, head; eye 

3.35 to 4.8; interorbital 3.35 to 3.8; 

mouth moderate, horizontal, inferior; 

maxillary reaching a little past front 

Geographic range: Coastal haters from 

Cape Cod, Classachusetts to the Bay 

of Campeche, Kexico, unconcon 

north of New Jersey. Conlniorl along 

the entire Gulf of Mexico coast 

but cost abundant off Louisiana 

and blississippi (Figure 2). 

'changed from Micropogon (preoccupied 

by ~~licropogon Boie 1826 in Aves) by 

White and Chi ttenden (1977). 

L~argely extracted from Hildebrand and , 

Schroeder (lSZC), Pearson (1S2'1), and 

Hoese and Moore (1977). See these 

references for explanations of abbreviations and measurements. 
i GEORGIA 

MILES 

50 100 

0 50 100 150 200 

KILOMETERS 

UNA MADRE Coastal distribution 

GULF OF MEXICO 

Figure 2. Distribution of Atlantic croaker along the Gulf of Mexico coast. 
of eye to below middle of eye, 2.3 to 

2.85 in head; teeth in the jaws all 

small, in broad villiform bands; chin 

with several pores and a row of short, 

slender barbels on each side; preopercle with stroncj, short spines on 

margin; gill rakers short; scales rnoderate, reduced anteriorly above lateral 

1 ine, strongly ctenoid, extending on 

the caudal but not on the other fins; 

dorsal fins contiguous, or more or less 

continuous in young, the first co~posed 

of slender spines, somewhat elevated, 

the third and fourth spines longest, 

higher than any of the rays in the soft 

part; caudal fin slightly double concave in adult, with the upper and middle rays longest, sharply pointed in 

very young; anal fin small, with two 

strong spines, the first very short, 

the second about two-thirds the length 

of the soft rays; ventral fins moderate, inserted under and slightly behind 

base of pectorals; pectorals rather 

long in adult, reaching well beyond 

tips of ventrals, scarcely reaching 

tips of ventrals in young, 1.15 to 1.5 

in head. 

Color in life: greenish or grayish silvery to brassy yellowish and 

highly irridescent above, silvery white 

below; back and sides with many brassy 

or brownish short, irregular, oblique 

bars formed by spots on scales. Bars 

may become less distinct in larger 

adults. Young usually paler, silvery. 

Larval and postlarval forms are described by Pearson (1929). 

REASON FOR INCLUSION IN SERIES 

The Atlantic croaker is one of 

several sciaenid fishes in coastal Gulf 

of Mexico waters that are subject to 

significant commercial and sport fisheries. It is the target species of an 

industrial groundfish fishery and is 

often dominant in inshore and offshore 

sport catches. The species is considered estuarine dependent as all stages 

from larvae to adults are known to 

occur in abundance in estuarine waters. 

Post larvae and juveni les grow rapidly 

in estuarine nursery grounds and are 

subject to predation by several other 

species. A1 though quantitative information is lacking, it is likely that 

croakers play a significant role in 

estuarine trophic dynamics. 

LIFE HISTORY 

Spawni -. nq 

Spawning by the Atlantic croaker 

has never been observed. The site and 

tirne of spawning are therefore inferred 

from the capture of ripe adults or 

early developmental stages. Host published works agree with the early work 

of Pearson (1929), who suggested that 

spawning occurs in the open gulf "near 

the mouths of the various passes that 

lead into the shallo~ bays and 

lagoons. " Bearden (1964), however, 

maintained that croakers along the 

South Carolina coast spawn entirely in 

the ocean as he found ripe females as 

far as 48 km (3G mi) offshore. Hildebrand and Cable (1930) also reported 

taking very young croakers 24 km (15 

mi) offshore. Spawning is reported to 

occur within a depth range of 7.8 to 

81 m or 26 to 266 ft (Fruge and 

Truesdale 1978). 

The Atlantic croaker, as with 

other sciaenids, has a protracted 

spawning season. Within its entire 

range, larval and postlarval stages 

have been collected in passes and bays 

from as early as August in Chesapeake 

Bay (Hildebrand and Schroeder 1928) to 

as late as June in Louisiana (Suttkus 

1955). The normal range for the Gulf 

of Mexico, however, appears to be from 

October to March with a peak in Noverr~- 

ber (Pearson 1929; Gunter 1938; Parker 

1971). A1 though Pearson (1929) reported 

"deluges of larvae . . . ," little 

information was found on the very 

important life history trait and modeling parameter of fecundity, and those 
few 1 i terature reports vary widely. 

For a female of 395 mm total length 

(TL): Hildebrand and Cable (1930) 

reported 180,000 uniform size eggs, but 

Hansen (1970) reported only 41,200 

eggs. No explanation for this disparity has been found. Eggs are pelagic 

and hatch in less than 1 week (Hildebrand and Cable 1930; Gutherz 1976). 

Larval Stage 

After hatching, larvae and postlarvae may spend some time in the 

plankton (Hi ldebrand and Cable 1930), 

but apparently soon become demersal 

(Hildebrand and Cable 1930; Fruge and 

Truesdale 1978). A demersal habit 

would concur with Pearson's (1929) 

observation that larvae were caught 

primarily in the deeper waters of the 

passes. It is unclear whether the 

movement of larvae into the estuaries 

is passive or active or a function of 

both. Perkins (1974) stated that "the 

reaction current may carry the newly 

hatched fish over 100 miles upstream to 

the upper limits of the saltwater intrusion . . . this first movement is 

passive. " However, Pearson's (1929) 

observations of pos tlarval croakers 

suggest that the movement is, at least 

in part, an active process. He stated, 

"A determined attempt. . . to gain the 

shelter of the bays was observed on 

many occassions. Few fish could breast 

the strong current of the ebb tide, but 

the young croakers, passed in schools, 

were seen attempting to enter the 

passes by hugging the sides of channels 

and to take advantage of the slower 

currents. " This schooling behavior is 

maintained throughout life. 

-- Postlarvae and Juveniles 

Once in the estuaries, the postlarvae and very young spread throughout 

with heaviest concentrations at the 

headwaters (Pearson 1029; Gunter 1938; 

Parker 1971). Specific areas of abundance for Lake Eorgne, Louisiana, and 

Galveston Bay, Texas, were identified 

by Parker (1S71), but he stated more 

generally that areas of concentration 

were "always in shallow water less 

than 1.2 m deep and in close proximity 

to a source of freshwater or brackish 

water which generally flowed through 

marshes or tidal flats." The Gulf of 

Mexico Fishery Management Counci 1 

(GMFMC 1981) reported abundant juveniles in the cordgrass (Spartina 

alterniflora) marshes of Louisiana in - 

both open and vegetated areas of 1 rn or 

less and stated that "brackish marsh is 

thought to be very important to juvenile development" (but see Substrate 

section). 

Young croakers remain in estuarine 

nursery areas at least through spring 

and early summer (growth and diet during this period are discussed later) 

before migrating to the gulf waters. 

Parker (1971) suggested that emigration 

may begin as early as April (Texas) or 

June (Louisiana) with the attainment of 

60 to 85 mm TL. The significance of 

these lengths, however, was not discussed, and later in this same report 

he stated that peak gulfward migration 

in Louisiana occurs from Septeniber to 

November. October to Nov~~ber is the 

most commonly cited peak rigration 

period from the Gulf of Mexico (Gunter 

1938; GMFMC 1981) and also (at least 

for Louisiana) the period of greatest 

average drop in surface water temperature between successive months 

(Barrett 1971). Nearly a1 1 reports 

suggest that this seaward migration is 

tied closely to decreasing temperatures 

in the estuaries (Pearson 1929; Gunter 

1938; Wallace 1940; Parker 1971; GMFMC 

1981). However, Etzold and Christnas 

(1979) stated that "migration general ly 

starts in surmer and peaks with decreasing temperatures in the early 

fall." If this and the earlier dates 

suggested by Parker (1971) are correct, 

temperature decrease may not actually 

"trigger" the migration, but instead 

sufficiently accelerate those processes 

"5.4 mm = 1 inch. 
that provide a common association of 

"peak" migration with periods of rapid 

temperature change. 

Seaward migrating young-of-thcyear arc subject to depletion by both 

shrimp and groundfi sh fisheries (Pearson 1929; GMFMC 1981) operating in 

the open gulf waters. A single, very 

tentatively suggested estimate of 

instantaneous fishing mortality (F) is 

given by GMFMC (1981) as 1.0, or an 

annual expectation of death due to 

fishing of 63%. However, no comparison 

of F with instantaneous natural maturity (M) was found in the literature. 

blaturi ty and Life-Span 

Most authors maintain that croakers mature at the end of their second 

year (Pearson 1929; Gunter 1945; Johnson 1978), but others report that some 

may mature and spawn before their 

second year is completed (Avaul t et al. 

1969; Hansen 1970; Etzold and Christmas 1979). Wall ace (1940) reported 

that males mature at 2 years and females at 3 years of age. Surviving 

spawners and juveniles (by then the 1t 

yr-class) overwinter in the gulf and 

return to the estuaries the following 

spring. The cycle may repeat several 

times during the lifetime of a single 

fish, as at least some members of the 

species 1 ive to 4 to 5 years of age but 

rarely greater (Parker 1971; Etzold and 

Christmas 1979). 

No one has suggested that this 

species dies after spawning, and there 

have been no reported observations of 

massive numbers of spent Atlantic 

croaker carcasses (e.g., in trawls, 

along shore) as is common for salmonid 

and osmerid species of more temperate 

waters. However, from earl iest authors 

there has been the hint of high postspawning mortal i ty. Pearson (1029) 

reported that after spawning in the 

fall of their second year, croakers 

"return in small numbers" and that it 

"may be that most croakers die after 

spawning. " This observation is echbed 

by Gunter (l938), Parker (1S71), and 

others. It is possible that this 

observation may simply be a false 

impression resulting froin a normally 

high natural mortality or high overwinter fishing mortality or both. As 

mentioned above, however, almost no 

infomation exists on mortality or on 

the percentage of returning spawners. 

GROWTH CHARACTERISTICS 

Parker (1971) reviewed the 1 i terature on the growth of croakers. He 

reported averages from these studies to 

be 12.1 mm/lno TL (145 mmlyr) in the 

first year, 5.3 mm/mo (64 vm/yr) in the 

second year and 3.6 mmlno (43 mrn/yr) in 

the third year. In his own study, the 

slope of the length-weight reqression 

curve was significantly preater than 

three (according to the "cube law" of 

isometric growth). Parker attri huted 

this to increasing condition with increasing size rather than to allonetric 

growth. His length-weight regression 

equation for croakers from Gal veston 

Bay, Texas, was: 

log W = -5.21 + 3.10 log L 

where: h' = preserved wet wt (g) 

(no conversion equation for live wt/ 

preserved wt was 

given) 

L = total length (~m) 

Parker's finding of a relatively 

low mean condition factor for croakers 

in summer appears to support the ohservation of Hildebrand and Cable (1930) 

that growth rate in the croaker is 

highest in spring and fall. Parker 

a1 so discussed year-to-year and geographic variation in growth rate. While 

year-to-year variation was apparent, he 
presented no convincing evidence of 

geographic variation. The only two 

growth . studies conducted in the same 

year (one in Florida, one in Texas) 

showed similar results. 

COPIMERCIAL AND SPORT FISHERIES 

The Atlantic croaker is the primary target species of a multispecies 

groundfish fishery in the Gulf of 

rlexico (GMFMC 1981). Commercial fishing is centered in a "primary area" 

(Point AuFer, Louisiana, to Perdido 

Ray, Florida). Most of the commercial 

catch used for human consumption is 

landed in Alabama (see Table 1). The 

Gulf of Mexico Fishery Management Council (1981) estimated that groundfish in 

this primary area are being exploited 

at or near the estimated naximum sustainable yield (MSY) of 486,000 mt, 

but "the greatest proportion (approximately 300,OOC mt) is the incidental, 

unwanted catch and discard of the 

shrimp fishery." Total annual landings 

by the directed groundfish fisheries 

are about 56,000 mt, approximately 69% 

of which is Atlantic croaker. Groundfish MSY for the entire gulf (within 

the U.S. 2C0-mi Exclusive Economic 

Zone) was estinated (for 1981) at 

1,C70,000 mt, optimum sustainable 

yield (OSY) at 819,160 mt and expected 

annual domestic harvest at 599,680 mt. 

The canned petfood industry is the primary user of the groundfish catch. 

Other uses of commercial ~roundfi sh 

i ncl ude f i shmeal and the devel oping 

Suritri industry which produces domestic 

and foreign (Japanese) Kanaboko (sausage). None of the fishes which form 

the bulk of the groundfish stock has an 

assigned legal status and the fishery 

remains unregulated. Recent (1Q74-80) 

declines in total landings and catch 

per unit effort (CPUE) of the industrial fleet were reviewed by the CFIFPC 

who have presented a management plan 

suggesting remedial actions. The plan 

has not yet been adopted. 

The croaker also supports a substantial sport fishery a1 though. it is 

usually considered a 1 ess preferred 

species than several other sciaenids 

(e.g., spotted seatrout, black drum, 

and red drum). In 1P70, the narine 

sport catch of croaker for the Culf 

of Mexico was estimated at 28,483 mt, 

Table 1. The weight and value of the commercial catch (for human consumption) 

of Atlantic croaker from the Gulf States and other areas in 1976 (National 

Marine Fisheries Services, U.S. Fishery Statistics for 1976). 

Location Weight (mt)a 3b Value (dollars x 10 ) 

Florida west coast 

A1 abama 

Mississippi 

Louisiana 

Texas 

Gulf of Mexico (total) 

United States (total ) 

a Weight = round (1 ive) weight, rnt = metric tons (2204.6 Ib). 

b~alhe =gross dollars to the fishermen (exvessel prices). 
nearly nine times the 1976 commercial 

landings for human consumption in the 

same area (the most recent years that 

data were available). Both commercial 

and sport catches are best from early 

summer to late fall (Gunter 1938; Kobylinski and Sheridan 1979; GMFMC 1981). 

The commercial catch is largely composed of 0+ and 1+ age groups (Etzold 

and Christmas 1979; GMFMC 1981). 

Croakers over 2 years old are largely 

limited to the sport fishery. Croakers 

are caught in estuaries and bays by 

small boat fishermen, but many are also 

taken near offshore oil platforms 

(Gu therz 1976). 

Etzold and Christmas (1979) concluded that croakers in the Gulf of 

Mexico represent a single stock. However, the mechanism for maintenance of 

stock integrity seems unclear as they 

further suggested that there are consi stent size differences (not mentioned 

by Parker 1971) between fish caught on 

either side of the Mississippi River 

and that there is little longshore 

migration. It seems necessary for proper management in the future to clarify 

the issue of a single versus multiple 

stocks, especially in light of the 

disparate level s of fishing pressure 

(GMFMC 1981) received by the croaker 

and other groundfish species in various 

areas of the Gulf of Mexico. 

Both GMFMC (1981) and Etzold and 

Christmas (1979) reported a wide yearto-year fluctuation in apparent croaker 

abundance. GMFMC (1981) further suggested that such fluctuations "imply 

environmental :ondi tions have had and 

will continue to have a strong impact 

on the stock. . . . " A1 though environmental conditions historical ly may have 

played the major role in determining 

stock abundance, GHFMC (1981) a1 so 

suggested that the exceptionally high 

groundfi sh harvests (primarily as 

shrimp by-catch) in 1975-76 "may have 

had a detrimental influence on the 

production of potential recruits in 

1977. " They additional ly warned that 

although this cannot be determined 

based on the available information, 

"lack of information should not cause 

the warning signal to be ignored." 

ECOLOGICAL ROLE 

The Atlantic croaker as a species 

cannot be assigned to a single trophic 

level, as dietary shifts occur during 

their 1 ifetime (Darnel 1 1958, 1961). 

Darnel1 (1958) described four active 

feeding stages, but 1 ater (Darnel 1 

1961) presented only three '(see Table 

2). While feeding habits between these 

stages may be fairly distinct, feeding 

within stages is apparently rather nonselective (Parker 1971). 

No information was found on the 

duration of the yolk sac stage or 

whether or not active feeding begins 

during or only after this stage. Larval 

and post1 arval croakers are 1 argel y 

zoopl anktivorous and may be considered 

secondary consumers. Several authors 

have reported detritus to be a major 

component of the juvenile diet (Darnel1 

1961; Parker 1971; Etzold and Christmas 

1979). Etzold and Christmas (1979), in 

addition to the items 1 isted in Table 2 

(footnote b), a1 so mentioned miscell aneous plants. It is possible then that 

croakers may play a minor role as primary consumers, but it is not clear 

that ingested plant material (whether 

discrete. or detrital) is assimilated. 

Other than the initial zoopl anktivorous 

stage, all sizes of croakers are reported to ingest benthic microinvertebrates. This is consistent with the 

1 aboratory observations of Roe1 ofs 

(1954), who found that croakers "dived 

deeply into the bottom with sove force, 

digging as they fed, and were thus able 

to obtain subsurface material. " Adults 

appear to feed similarly to juveniles, 

but are also capable of taking larger 

invertebrates and fishes. As juvenile 

and adult, therefore, the croaker nay 

operate as a secondary, tertiary, or 

higher 1 eve1 consumer. The importance 
Table 2. Food habits of three size classes of Atlantic 

croaker, Micropogonias undulatus (by percent of diet). a 

Size class (nmTL) 

Food category 10-49 50-124 125-325 

Zooplankton 

Detritus 

Microinvertebrates b 

~i shesC 

Macroinvertebrates d 

a~abular data from Darnel1 (1961). No mention was made of the method for 

estimation of percent diet. 

b~ncludes isopods, amphipods, chironomid larvae, small clams, mussels, 

small crabs (others have included polychaetes, harpacticoid copepods, 

foraminifera, os tracods, minute snai 1 s , and col eopteras) . 

C~ncludes ophichthid eels, pipefish, sheepshead minnows (others have 

included small croakers, gobies) . 

dlncludes Rangia clams, mud crabs, blue crabs, grass-mud-river shrimps 

(others have included the commercial penaeid shrimps). 

of each of the various feeding stages 

of croakers as consumers depends upon 

their number and rate of ingestion. No 

quantitative study of the role of 

croakers in estuarine trophic dynamics 

was found in the literature. 

At a community interaction level, 

croakers have been recorded as prey for 

larger fishes including larger adults 

of their own species (Pearson 1929; 

Gowenlach 1933), but again the quantitative importance of the croaker as a 

prey item is not known. Parker (1971) 

concluded from diet and distributional 

overlap data that "spot and croaker 

were found to be in direct competition." There is, however, no experimental evidence to support such a conclusion, and the use of overlap data 

to infer competition is clearly insufficient and open to misinterpretation 

(Colwell and Futuyuma 1971). Gulf of 

Mexico Fishery Management Council 

(1981) discussed the shrimp-associated 

communities of Gulf of Mexico groundfishes. Their definition of the groundfish "stock" as a group of species with 

"similar life histories . . .and common 

habitat requirements" is similar to the 

concept as defined by Root qyiLd7). They further suggested that 

"unchanged relative abundance [of 

species comprising the groundfish 

stock] . . . suggests stability in the 

groundfi sh ecosystem. " 

ENVIRONMENTAL REQUIREMENTS 

Temperature 

The role of temperature as a key 

to the fall emigration of croakers from 
estuaries has a1 ready been discussed. 

Rising temperatures (16°C [61 OF] or 

more) may also induce immigration inshore during spring (Johnson 1978). 

Fie1 d and laboratory data both indicate 

that juveniles are more tolerant of 

1 ower temperatures than adul ts. Parker 

(1971) reported that juveniles have 

been taken in waters from 0.4" to 

35.5"C (33" to 96°F) as compared to 5" 

to 35.5"C (41" to 96°F) for adults. 

Laboratory tests establ ished lower and 

upper lethal temperatures of 0.6' and 

38°C (33' and 100°F) for juveniles, and 

3.3" and 36°C (38" and 97°F) for 

adul ts, respectively (Schwartz 1964). 

Sudden and prolonged cold snaps which 

occur while the croakers still inhabit 

the shallower estuarine areas can cause 

mass mortal i ties (Hi1 debrand and Cable 

1930; Gunter and Hi1 debrand 1951). 

Parker (1971) found the highest abundances of croakers in waters from 21" 

to 25°C (70" to 77"F), but stated that 

"most months, croakers appeared to be 

rather evenly distributed over the 

range of available temperatures" except 

that older fish (over 1 year old) were 

largely absent in waters below 10°C 

(50°F). Postlarvae were taken in 

waters from 6" to 20°C (43" to 68"F), 

but a wider tolerance range was suspected. Parker (1971) a1 so suggested 

that croaker can grow well at temperatures from 12.8" to 28.4"C (55' to 

83°F) and possibly from 6" to 32°C (43" 

to 90°F). 

Salinity 

Croakers have been collected in 

waters from very dilute (0.2 ppt) to 

hypersal ine (75 ppt) (Simmons 1957; 

Parker 1971). The survivorship of 

croakers at the upper end of this range 

is unknown and occurrence in such 

waters is uncommon. Parker (1971) 

stated that "the nature of the life 

history of the Atlantic croaker requires that postlarvae and juveniles 

be adaptive, not only to a comparatively broad salinity range, but also 

to re1 atively rapid sal ini ty changes. " 

No information was found on the latter, but larvae and juveniles have 

been taken in salinities ranging from 

near 0 to 36 ppt. Etzold and Christmas 

(1979) reported that croakers were 

taken from all ranges of salinity in 

Missi ssppi waters with biggest catches 

in waters from 15 to 19 ppt. Parker 

(1971) cautioned that many observed 

tendencies to lower salinity water may 

be easily interpreted as habitat preference for features other than salinity. This may be the case with the 

observation of Kobyl inski and Sheridan 

(1979) that croakers were "noticeably 

absent from the higher salinit (avg. 

19.2 ppt) grass bed stations" hut see 

Substrate section). No reports of significant penetration into freshwater 

were found in the 1 iterature. 

Depth 

Immediate post-settlement and nursery depths have been discussed in the 

Life History section s have suspected 

spawning depths. Gul I of Mexico Fishery Management Council (1981) reported 

that groundfish stocks in the Gulf of 

Mexico occur at highest densities in 

waters of less than 91 m (300 ft). 

During the warmer months most are in 

waters less than 18 m (60 ft). Winter 

stock concentrations are greatest in 18 

to 55 m (60 to 180 ft). In Louisiana 

waters west of the Mississippi River, 

croakers dominated to 46 m (150 ft). 

Near the mouth of the river they dominated to a depth of 91 m (300 ft), 

migrating in winter to depths of 64 to 

110 m (210 to 360 ft). The effects of 

this winter migration on the species 

composition of white and brown shrimpassociated communities are a1 so discussed by GMFMC (1981). Deep navigational channels may be used heavily by 

immigrating 1 arvae and postlarvae in 

winter months (Wallace 1940), but 

Parker (1971) reported that he generally found the fewest juvenile croakers 

in such channels and concluded that 

they did not serve as nursery areas. 

No reference to sexual differences in 
depth selection among croakers was 

found. 

Substrate 

No experimental studies of substrate preference by croakers were 

found in the 1 i terature. Information 

presented here is inferred from fie1 d 

observations and should thus be considered a statement of association and not 

necessarily preference. Beyond the 

planktonic stage, virtually all sizes 

of croakers are most often associated 

with soft bottoms (Pearson 1929; Gunter 

1938; and others), particularly those 

containing large quantities of detritus 

(Parker 1971). Juveniles have been 

reported (GMFMC 1981) to occur abundantly in both open and vegetated 

shallow (about 1.2 m [4 ft] or less) 

marsh areas. Kobyl inski and Sheridan 

(1979), however, found few croakers in 

areas of dense benthic macrophytes. It 

is unclear whether this discrepancy between the two reports is real or due to 

differences in sampling technique. 

Adults are associated with similar mud 

or mud-sand substrates in somewhat 

deeper waters and often, unlike juveni les, inhabit navigational channels. 

Adul ts have a1 so been c o l l e c t e d over 

oyster, coral, or sponge reefs (Johnson 

1978) and near bridges, piers or similar structures (Gunter 1938; Gutherz 

1976; GMFMC 1981). 

Other Environmental Factors 

No published information on the 

dissolved oxygen requirements of croakers was found. Other than the previously quoted observations of Pearson 

(1929) and Perkins (1974) in reference 

to larval immigration, no information 

specifically addressing water velocity 

was found. Perkins (1974) further 

noted that postlarvae, upon reaching 

their furthest point upstream, "gather 

and move downstream [seaward] as they 

grow . . . the movement downstream is 

an active pt i\cess. " No mention is made 

of orientaT~on during such movements or 

whether they are genetically determined 

or related to particular environmental 

cues. Kobyl inski and Sheridan (1979) 

in their study of spot and croaker commented that the reproductive pattern of 

croakers might have evolved such that 

occurrence of planktivorous stages (up 

to 15 mm) coincides with peak river 

flow and "may depend on annual floc iing." Should this be the case, alterdtion of normal seasonal runoff pattern (e. g., by flood control measures, dams) 

m~ght be expected to affect croaker 

production. 

A1 though no study specifically 

addressing larval croakers was found, 

Stern and Stickle (1978), in a review 

of the effects of turbidity and suspended material in aquatic envi ronments, concluded that within a given 

species, the early developmental stages 

generally were more sensitive to concentrations of suspended solids than 

were adults. Kobylinski and Sheridan 

(1979) found croakers to be particularly abundant in areas "influenced 

by a highly turbid runoff." Parker 

(1971) also noted a tendency toward 

higher croaker densities in turbid 

areas. He attributed this observation 

to increased food availability and the 

possi bi 1 i ty of predator protection 

afforded by decreased visi bi 1 i ty. 

To date, over 90 parasites and/or 

diseases have been identified from the 

croaker (Etzold and Christmas 1979). 

Several of the larval nematodes "would 

present a human health problem" only if 

eaten raw (Etzold and Christmas 1979). 

The effects of these parasites and 

diseases on the survival and growth of 

croakers are not yet known. 
LITERATURE CITED 

Avault, J.W., Jr., C.L. Birdsong, and 

W.G. Perry. 1969. Growth, survival, food habits and sexual 

development of croaker, Micropogon 

undulatu~, in brackish water 

ponds. Proc. Southeastern Assoc. 

Game Fish Comm. 23:251-255. 

Barrett, B.B. 1971. Cooperative Gulf 

of Mexico estuarine inventory and 

study, Louisiana: Phase I I, Hydrology and Phase 111, Sedimentology. 

Louisiana Wildlife and Fisheries 

Commission, New Orleans. 191 pp. 

Bearden, C.K. 1964. Distribution and 

abundance of At1 antic croaker, 

Flicropogon undulatus, in south 

Carolina. Contrib. Bears Bluff 

Labs 40: 1-23. 

Colwell, R.K., and C.J. Futuyuma. 1971. 

On the measurement of niche 

breadth and niche overlap. Ecology 

52(3) ~567-576. 

Darnell, R. 1958. Food habits of 

fishes and large invertebrates of 

Lake Pontchartrain, Louisiana, an 

estuarine community. Publ. Inst. 

Mar. Sci. Univ. Texas. 5:353-416. 

Darnell, R. 1561. Trophic spectrum of 

an estuarine community, based on 

studies of Lake Pontchartrain, 

Louisiana. Ecology 42(3) :553-568. 

Etzold, D.J., and J.Y. Christmas. 1979. 

A Mississippi marine finfish management plan. MS-AL Sea Grant Consort ium MASCP-78-046. 

Fruge, D.J., and F.M. Truesdale. 1978. 

Comparative larval development of 

E.licropocjonn jndulatus and Leiostomus xanthurus (Pisces: Sciaenidaq -- --- 

from the northern Gulf of Mexico. 

Copeia 1378(4) : 643-648. 

Gowenlach, J.N. 1933. Fishes and fishing in Louisiana. La. Dep. Conserv. Eull. 23. 

Gulf of Mexico Fishery Flanagement Council (GNFMC). 1981. Draft fishery 

management plan envi ronmenta 1 

impact statement and regulatory 

analysis for groundfish in the 

Gulf of Mexico. GMFMC, Tampa, Fla. 

Gunter, 6. 1938. Seasonal variations 

in abundance of certain estuarine 

and marine fishes in Louisiana, 

with particular reference to life 

histories. Ecol. Monogr. 8(3): 

315-346. 

Gunter, G. 1945. Studies on marine 

fishes of Texas. PuL1. Inst. Mar. 

Sci. Univ. Texas. 1:l-190. 

Gunter, G., and H.H. Hi ldebrand. 1951. 

Destruction of fishes and other 

organisms on the south Texas coast 

by the cold wave of January 28- 

February 3, 1951. Ecology 32(4): 

731-736. 

Gutherz, E.J. 1976. Northern Gulf of 

biexico groundfish fishery, including a brief life history of the 

croaker (Kicropogon undul atus). 

Gulf Caribb. Fish. Inst. 29:87- 

101. 

Hansen, D.J. 1970. Food, growth, 

migration, reproduction, and 

abundance of pinfish, Lagodon 
rhomboides, and Atlantic croaker, 

Micropogon undulatus, near Pensacola, Florida, 1963-65. Fish. 

Bull., U.S. 68(1): 135-140. 

Hildebrand, H.H., and L.E. Cable. 1930. 

Developr:,ent and life history of 

fourteen teleos tean fishes at 

Beaufort, North Carolina. Eull. 

U.S. Bur. Fish. 46:383-488. 

Hildebrand, ti.H., and U.C. Schroeder. 

1928. The fishes of Chesapeake 

Bay. Eull. U.S. Eur. Fish. 43 

(Part I ) : 1-366. 

Hoese, H.D., and R.H. Noore. 1S77. 

Fishes of the Gulf of Mexico: 

Texas, Louisiana, and adjacent 

waters. Texas A&!{ University 

Press, College Station. 

Johnson, C.D. 1978. Developoent of 

fishes of the !.lid-Atlantic bight: 

an atlas of egg, larval and juvenile stages. Vol. 4. Carangidae 

through Ephippidac. U.S. Departrient of the Interior, Fish and 

hi ldl ife Service. FI;S/OBS-78/12. 

314 pp. 

Kohyl inski, C. J., and P. F. Sheridan. 

1979. Distribution, abundance, 

feeding and long-term fluctuations 

of spot, Cciostomus xanthurus, and 

croaker, Micropoqonias undula tus , in ~~alachicola Bay, Florida. " - 

1972-1'977. Contrib. Nar. ~ci : 

22: 149-161. 

Parker, J.C. 1971. The biology of 

spot, Leios torus xanthurus Lacepede, and Atlantic croaker, Micropogon undulatus (Linnaeus), in two 

Gulf of Mexico nursery areas. Sea 

Grant Publ. No. TAMU-SG-71-210. 

Texas A&M Univ., College Station. 

Pearson, J. C. 1925. Natural history 

and conservation of the redfish 

and other comniercial sciaenids of 

the Texas coast. Eull. U.S. Eur. 

Fish. 44: 12s-214. 

Perkins, E.J. 1?74. The biolosy of 

estuaries and coastal waters. 

Aciideriic Press, Kew York. 

Roelofs, E.L. 1954. Food studies of 

young sciaenid fishes, Piicropoaon 

and Leiostocus, from North Caro- - - -- - - -. 

lina. Copeia 1954(2):151-153. 

Root, R.B. 1SE7. The niche exploitation pattern of the blue-gray 

anatcatcher. Ecol. Monogr. 37: 

317-350. 

Schwartz, F.J. 1SG4. Effects of winter 

water conditions on fifteen species of captive rarine fishes. 

An:. iRidl. Flat. 71(2):434-444. 

Simmons, E.G. 1957. An ecological 

survey of the Upper Laguna Madre 

of Texas. Publ. Inst. Var. Sci. 

Univ. Texas. 41 (2) : 156-200. 

Stern, E.M., and W.R. Stickle. 197C. 

Effects of turbidity and suspended material in aquatic environrients: 1 i terature review. U.S. 

Army Eng. Waterways Exp. Stn., 

DKRP Tech. Rep. D-78-21. 

Suttkus, R.D. 1955. Seasonal r~ovements 

and growth of the Atlantic croaker 

(Clicropoqon undulatus-) along the 

east Louisiana coast. Proc. Gulf 

Caribb. Fish. Inst. 7: 151-158. 

Wallace, D. H. 194C. Sexual development of the croaker, Kicropoqon 

undulatus, and distribut7rn of the --- 

early stages in Chesapeake Bay. 

Trans. An. Fish. Soc. 7C:475-482. 

White, K.L., and M.E. Chittenden, Jr. 

1977. Ase determination, reproduction and population dynanics of 

the Atlantic croaker, RicropoqoZ 

nias undulatus. Fish. Bull., U.S. -- 

75: 109-123. 
~-.---.__-I_^_^_-_ -- 

4. Tltle and Subtttle 

Species Profiles: Life Histories and Environmental Requirements 

(Gulf of Mexico) -- Atlantic Croaker I 

50272 -101 

--- .- - 

7. Author(~) 

Dennis R. Lassuy -. .- ~~- 

9. Performing Organization Name and Address 

U.S. Fish and Wildlife Service 

R ivision of Biological Services 

ational Coastal Ecosystems Team 

1010 Gause Boulevard 

REPORT DOCUMENTATION '>REPORT NO 2 

l~lidell, LA 70458 -- - 

12. Sponsoring Organization Name and Address 

3. Rec~poent's Accerrton No 

National Coastal Ecosystems Team U.S. Army Corps of Engineers 

Fish and Wild1 ife Service Waterways Experiment Station 

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

Washington, DC 20240 Vicksburg, MS - 39180 

15. Supplementary Notes 

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

PAGE Fws/oBs-82/11.3* I 1 - -- 

5 Repan Date 

- February 1983 --- 

-- 

6 

-- --- 

I -- - 

8. Perform~ng Organlratton Rept. No 1 11. ContractfC) or Grant(G) No. 

IC) I +- -. - - - - - 

1 13. Type of Re~orf 8. Perlod Covered-I 

16. Abstract (Llmlt: 200 words) 

Species profiles are literature summaries on the taxonomy, morphology, range, life history, 

and environmental requirements of coastal aquatic species. They are desiqned to assist in 

17. Document Analysts a. Descriptors 

environmental impact 'assessment. The ~tlantic croaker, ~icro~o~onias undulatus, is one of 

the most abundant Gulf of Mexico species and is caught by commercial and sport fishermen. 

It is the main species of an industrial groundfish fishery and is estuarine dependent. 

Spawning occurs from October to March in the nearshore Gulf of Mexico and larvae move into 

and use shallow estuarine areas, usually near marshes, for nurseries. Postlarvae and 

juveniles remain in estuaries until fall when they migrate to the Gulf of Mexico. Adults 

inhabit estuaries, inshore, and offshore waters. Croakers have high mortality rates and few 

live beyond 5 years. Adults are primarily benthic carnivores. Adults have been collected i 

a temperature range of 5" to 35.5"C and a salinity range of 0.2 to 75 ppt. Early life stages 

tolerate lower temperatures and salinities better than the adults. 

Estuaries 

Fishes 

Growth 

Feeding 

I 

b. Identifters/Dpen.Ended Terms 

At1 antic croaker 

Micropogonias undulatus 

Habitat 

Sal ini ty requirements 

~em~erature .requi rements c. COSATI FieldlGroup 

- -- - -- 

spawning 

18. Availability Statement 

Unlimited 

(See ANSI-239.18) OPTIONAL FORM 272 (4-771 

(Formerly NTIS-35) 

Department of Commerce 

19. Security Class (This Report) 

- 

Unclassified 

20. Securlty Class (This Pape) 

Unclassified 

21. No. of Pages 

12 

22. Price 
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