Historical changes in age and growth of Atlantic croaker, Micropogonias undulatus (Perciformes: Sciaenidae)

Journul

ofArchoeologica1

Science

1992,

19,13-99

Historical Changes in Age and Growth of Atlantic Croaker, Micropogonias undulatus (Perciformes: Sciaenidae) L. Stanton Hales Jr” and Elizabeth J. Reitzh (Received 20 December 1990, revised manuscript accepted 14 March 1991) Archaeological excavations near St Augustine, Florida, U.S.A. recovered 415 otoliths from Atlantic croaker, Micropogonias undularus (Perciformes: Sciaenidae), which were caught by Native American and Hispanic peoples living in the area. Age determination using growth increments of otoliths and correlated size information were used to construct size distributions, age distributions, growth rates and season of capture. During a 3000 year time span, coastal Indians captured Atlantic croaker I-10 years old ranging from about 13-39 cm total length. Marginal increments of otoliths revealed that most fish were caught from January to May, during or shortly after the period of annulus formation. Numbers and size ranges of otohths in each archaeological sample were quite small, suggesting that Indian fishing was probably done by individuals or small groups. Gears and methods used by Indians were selective for small, young croaker or were inefficient in areas where large fish occurred. The absence of large, old croaker and nearshore coastal species in Prehispanic collections suggest that Indians fished predominantly in the estuary. Spanish interaction with coastal Indian tribes resulted in changes in the size and age composition of the Atlantic croaker catch. Postcontact, older (up to 15 years) and larger (up to 46 cm, tip of the jaw to the end of the caudal fin-TL) croaker formed a large portion (> 30%) of the catch, suggesting that fishing effort was more extensive throughout estuaries and nearshore coastal waters and may have employed other gears and methods. Marginal increments of otoliths suggest that fishing occurred primarily in winter and spring but may have extended year-round. Comparing information from these collections with modern studies indicates that age and growth of Atlantic croaker have changed dramatically, perhaps in response to exploitation or habitat alteration. In earlier centuries, Atlantic croaker grew more slowly, perhaps an indication of density-dependent growth, and lived much longer (15 years versus 7 years). Differences in age and size class composition of Prehispanic, First Spanish Period, and modern catches are consistent with those of a species whose rates of exploitation have increased. Future research of environmental conditions and the biology of Atlantic croaker and other fishes during these early periods may provide explanations for the dramatic changes in the biology of Atlantic croaker observed in this study. Keywords: SOUTH-EASTERN U.S.A., PREHISTORIC AND HISTORIC AMERICAN INDIAN, PREHISPANIC AND HISPANIC PERIODS, ESTUARINE FISHES, SUBSISTENCE FISHING STRATEGIES, FISHERY BIOLOGY, AGE AND GROWTH, OTOLITH ANNULI, SCIAENIDAE, ST AUGUSTINE. FLORIDA.

“Department of Zoology and Institute of Ecology, University GA 30602, U.S.A. hMuseum ofNatural History, University of Georgia. Athens,

of Georgia, GA 30602,

Athens, U.S.A.

73 03054403/92/010073

+27

$03.00/O

0 I992 Academic

Press Limited

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Introduction

Fishes constitute a diverse, dominant component of zooarchaeological material from prehistoric and historic coastal sites (Wheeler & Jones, 1989). Although information is available about fish catches by diverse cultures on several continents (e.g. Leach & Anderson, 1979; Akazawa, 1980; Balme, 1983; Heinrich, 1986; Hongo, 1989) archaeological and ethnohistorical information about subsistence fisheries of American Indian cultures in the south-eastern U.S.A. is limited (Rostlund, 1952; Hultkranz, 1984; Reitz, 1985; Reitz & Quitmyer, 1988). More importantly, nothing is known about any aspect of the fish populations that native cultures exploited in the south-eastern U.S.A., and little is known elsewhere (Casteel, 1976; Wheeler&Jones, 1989). Efforts have been made to use estimated fish size, age information and growth patterns to understand fishing techniques and schedules of other human cultures. Balme (1983) reported that differences in numbers of parts (hundreds versus a few) recovered at archaeological sites reflected different fishing methods (nets versus traps) in New South Wales, Australia. Colley (I 983) suggested fishing practices in the Orkney Islands changed due to interaction (trade?) with outside cultures. Similarly, Heinrich (1986) suggested changes in species composition of fishes at Viking villages in Denmark, including the occurrence of fish remains for species not locally available, reflected the dietary preferences of early Christians. Incremental patterns (Morey, 1983; Noe-Nygaard, 1983; Brewer, 1987) and linear dimensions of selected skeletal structures (Akazawa, 1980; Balme, 1983; Colley, 1983; Wheeler & Locker, 1985; Hongo, 1989) found in archaeological deposits have been used to estimate fish size and seasonality of fishing. Although incremental patterns have been studied for invertebrates (Claassen, 1983; Deith, 1983; Quitmyer et al., 1985) such techniques have not been applied to fish material recovered in the coastal south-eastern U.S.A. Identification of large quantities of taxonomically diverse fishes in the south-eastern U.S.A. suggests that fishing was a significant subsistence activity by Native Americans and Europeans alike (Reitz, 1988; Reitz & Quitmyer, 1988). Native Americans appear to have used smaller fishes than did Europeans, suggesting that their fishing gears and locations differed. Fish biology has been less frequently examined using zooarchaeological materials despite the wealth of data they provide. Such information is based on temporal changes in fish growth recorded as contrasting increments, analogous to tree rings, in these structures, especially otoliths (e.g. Summerfelt & Hall, 1987). Combined with the allometric relationship between fish size and other skeletal dimensions (Wheeler & Jones, 1989) analysis of these marks provides information about the size, age and season of capture of fish. Casteel (1976) reported differences in growth rates of humpback sucker (Xyrauchen texanus) over the past 1000 years, but based his conclusions on only five specimens, four of which were modern. Casteel also reported that Soviet scientists found greater maximum sizes and ages in archaeological specimens than is found in the same four sturgeon species today. According to Casteel (1976: 132), these biologists reported lower growth rates and ages to maturity in individuals from 100 BC to AD 300 than in modern individuals and associated many changes with exploitation. Similar shifts might occur wherever fishing strategies changed from subsistence to commercial fisheries. However, demonstration of these changes requires ample biological information or material from both time periods and the same region. This paper provides descriptive and comparative information about the catch of Atlantic croaker, Micropogonius undzdatus (Perciformes: Sciaenidae), near St Augustine, Florida across several time periods. Information is based on otolith collections recovered from archaeological excavations at two sites with long occupational time spans (c. 1450 BC to AD 1765) by different cultures. The Atlantic croaker is well-represented in archaeological collections from these sites, is today among the most abundant and widely

HISTORICAL

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IN ATLANTIC

Anastasia

CROAKER

75

Island

Figure 1. Location of Fountain of Youth Park and Ft Mose near St Augustine, Florida in the south-eastern U.S.A. Distance scale on the inset applies to the large figure only.

distributed seasonal residents of estuarine and coastal waters of south-eastern and middle Atlantic states (Herke, 1971; Weinstein, 1979) and is highly sought today by commercial and recreational fishermen (Joseph, 1972; Gutherz, 1977). Thus, in addition to describing the seasonality, size and age composition of the catch, and likely fishing strategies, comparisons of archaeological and modern information provide a glimpse of changes in the biology of this species. Site History Otoliths and other vertebrate and invertebrate materials were excavated near St Augustine at two sites which have been occupied by several different cultures during the past 3200 years (Figure 1). The first site, Fountain of Youth Park (FOY), a tourist site with no demonstrable association with Ponce de Leon’s fabled search for eternal youth, is

16

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located approximately 1 km north of the Castillo de San Marcos; the second site is Gracia Real Santa Teresa de Mose (Ft Mose or FtM), situated 2 km north of FOY. Spanish and several Indian cultures have occupied the Fountain ofYouth Park site over different time periods. Earliest occupation at Fountain ofYouth Park dates to the Orange Period (Chaney, 1987), which began around 2000 BC (Milanich & Fairbanks, 1980: 152). The Orange Period (OP) is identified by fibre-tempered ceramics, production of which ended by 500 BC (Milanich & Fairbanks, 1980: 152). Details of ceramics identified from FOY suggest occupation of the site began in the Orange 3 Period (1450 and 1250 BC) and continued into the Orange Transitional Period (1200 or 1000 to 500 BC (Milanich & Fairbanks, 1980; Chaney, 1987). St Johns II (Chaney, 1987) the next period represented at FOY, is associated with Timucuan tribes (Milanich & Fairbanks, 1980) and had several subdivisions, some of which are represented at the site. The bulk of the St Johns IT (SJIT) material at FOY appear to be St Johns TIC (AD 1513-1565) a period of Spanish exploration of Florida without permanent European settlements. Interactions between Timucuans and Spanish explorers were limited and intermittent until the first permanent Spanish colony, which began the First Spanish Period (FSP). The Hispanic colony, founded in 1565 by Pedro Menendez de Aviles, occupied a coastal Timucuan village until hostilities forced the Spanish settlers to move, eventually establishing St Augustine at its present location in 1567 (Lyon, 1976). The origin of materials from the Contact Period is probably Hispanic subsistence during their occupation at FOY (Chaney, 1987). The last time period for which materials are available is the Mission Period from the late 16th through the early 18th century, when FOY was occupied by Timucuan, Guale and other Indian tribes associated with the Franciscan Nombre de Dios mission (Deagan, 1983). Otoliths from FOY therefore represent fishing techniques and fish populations exploited by Native Americans living at the site during Prehispanic periods (Orange and St Johns II) as well as during the First Spanish Period (Mission and possibly Contact). Gracia Real Santa Teresa de Mose was originally excavated by the Florida Museum of Natural History (Deagan & Landers, 1990) to research the early 18th century settlement of former slaves who had been granted sanctuary for conversion to Catholicism. During excavation otoliths were uncovered from an earlier Indian midden which could be assigned to the late Orange Period based on ceramic details (Marron, 1987). Fishery and Ecology of Atlantic Croaker The Atlantic croaker is among the most abundant and widely distributed sciaenid species, occurring from Cape Cod, Massachusetts, U.S.A., through Campeche Bay, Mexico; reports of its occurrence in the Greater Antilles southward down to Argentina are believed inaccurate (Chao, 1978). It is highly sought by recreational and commercial fishermen in many areas throughout its range, with total landings fluctuating around 10,000 tons annually (Fischer, 1978). Atlantic croaker occupy a variety of habitats during their life (Herke, 1971; Weinstein, 1979). Along the south-eastern U.S.A., Atlantic croaker generally spawn from late fall through winter well offshore (SO-100 km) (Johnson, 1978). Larvae enter estuaries in winter and early spring at about lo-20 mm standard length (Johnson, 1978). Juveniles use different estuarine habitats on a size-specific basis (Herke, 1971; Weinstein, 1979) remaining in estuaries and other estuarine habitats for their first year of life. Adults remain in high salinity coastal waters from one to several years before maturation. After reaching maturity, they annually migrate offshore to spawn in the autumn and return to estuaries in late winter and spring (Johnson, 1978). Differences in Atlantic croaker biology have been reported for populations north and south of Cape Hatteras (Johnson, 1978; Ross, 1988) with the population in the Gulf of Mexico similar to the south-eastern population (White & Chittenden, 1977). Populations in northern latitudes consist of a greater percentage of large (> 36 cm total length), old

HISTORICAL

CHANGES

IN ATLANTIC

CROAKER

II

(age class III or older) individuals. Mortality rates for the northern population of Atlantic croaker are reportedly lower than for more southern populations (Chittenden, 1977; Ross, 1988). Micropcjgonias un~ulutus also mature at different sizes (15-l 8 cm TL versus 20cm TL) and ages (I versus II) north and south of Cape Hatteras (Johnson, 1978). Distinct changes in the biology of many fishes distributed on both sides of Cape Hatteras have been previously recognized (Gunter, 19.50; White & Chittenden, 1977; Geoghegan & Chittenden, 1982; Ross, 1988), but explanations for these differences have been largely speculative. These authors noted the tendency for cool waters to produce larger, older, later-maturing individuals than do warm waters. The lack of identifiable genetic differences between populations distributed on both sides of Cape Hatteras (Sullivan, 1986; Ross & Sullivan, 1987) supports the hypothesis that environmental factors are responsible for observed size and age differences. Methods and Materials Material from FOY was recovered during two excavations in 1976 and 1985-7 under the direction of K. A. Deagan (Merritt, 1983; Chaney, 1987). Otoliths from Ft Mose were also excavated in 1985 under Deagan’s direction (Marron, 1987). Fauna1 materials were recovered with a l/4-in (6.35-mm) mesh screen during the 1976 excavation; all other otoliths were recovered using a l/4-in mesh screen held over a l/16-in (approximately I+8-mm) mesh screen. Fauna1 material in the larger fraction was collected in the field; fauna1 material in the smaller fraction was sorted in the Archaeology Laboratory at the Florida Museum of Natural History. Fauna1 identifications of all samples were made at the Zooarchaeology Laboratory of the University of Georgia Museum of Natural History and are reported elsewhere (Reitz, 1985, 1991). Details of samples containing otoliths of M. undulutus are given in Table 1. Those samples designated Unknown Prehispanic were clearly deposited prior to 1565, but the exact Prehispanic Period could not be determined from the ceramic evidence. The table indicates that otoliths were recovered from two major periods, the Prehispanic Period (comprised of Orange, St Johns and Unknown Prehispanic Periods) and the First Spanish Period (comprised of Contact and Mission Periods). To accurately identify archaeological material discussed in this manuscript, sample refers only to an individual field sample, and all samples from one period comprise a collection. Maximum otolith length (OL) was measured as the greatest anterior to posterior length. Because whole otoliths of Atlantic croaker are thick and opaque, otoliths were sectioned for age determination following a modification of Hales (1987). Briefly, the dorsal surface of all otoliths was removed by grinding with aluminium oxide sandpaper (240 grit) until the core was visible. The ground surface of the otolith was glued to a glass microscope slide with Duro Super Glue or Duro Crystal Clear Glass Adhesive (Loctite Corp., Cleveland, OH). The ventral surface was then ground away, resulting in a thin frontal section containing the otolith core (Figure 2). After sectioning, otoliths were measured with an ocular micrometre to the nearest 0.1 mm under reflected and transmitted light at 12 x and 24 x magnification. The otolith radius (OR) was measured from the core to the most distant margin. Measurements were made from the core to the edge of each optically dense (opaque) increment, assumed to be an annulus based on Barger (1985). These opaque increments form during periods of slow growth and alternate with translucent increments which form during periods of more rapid growth. The combination of one opaque and one translucent increment constituted 1 year’s growth. Measurements were made typically along the maximum radius present in each section. All otoliths were examined twice to count and measure annuli. Spearman rank correlation (Zar, 1974) was performed to evaluate the effect of screen size on the size of collected otoliths.

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Table 1. Zooarchaeolo~icalsamples FS no. FOY 71 FOY 76 FOY 103 FOY 248 FOY 280 FOY 288 FOY 289 FOY 300 FOY 306 FOY 308 FOY 318 FOY 337 FOY 338 FOY 1053 FOY 1059 FtM 1059 FtM 1085 FtM 1089 FtM 1090 FtM 1100 FtM 1105 FtM 1113 FtM 1115 FtM 1161 FtM 1162 FtM 1164 FtM I165 FtM 1167 FtM 1169 FtM 1170 FtM I171 FtM 1173 FtM 1175 FtM 1177 FtM 1183

N 13 150 20 7 3 9 4 77 10 4

7 15 3 2

5 5 2 3 14 5 9 5 9 6 1 2

containing

otoliths

qf‘Micropogonias

x

Size range

Period

14.4 14.0 14.6 15.6 14.1 13.0 13.2 11.8 13.9 14.1 7.5 11.8 14.1 8.1 10.1 12.2 12.9 11.6 13.2 12.4 11.4 11.5 12.3 12.2 11.9 11.3 10.2 13.5 12.7 IO.8 10.6 12.4 12.6 14.1 11.8

Il.1 17.7 9619.5 11.1-17.4 13.6-17.4 13.5514.8 12.5-13.9 10.3315.7 10.2-13.9 7.0-19.2 12.7-16.4 6.2 9.8 1OG13.6 14.1 6.7-9.6 IO.1 9.9-l 6.2 9.7-16.4 11412.3 1 lG15.9 11.9913.0 lOG13~3 8Gl3.6 10.9913.5 11.7~13~4 11.5512.6 6.8-14.8 8.7-l 1.5 13.5 IO&l 5.7 8.2-12.6 9.9-l 1.9 10.5-15.3 11.3-14.4 14.1 10615.2

Mission* Mission* Mission* St Johns IIc Unk. Prehisp. St Johns 11~. Unk. Prehisn. Orange Contact Orange St Johns IIc Orange St Johns IIc Mission+ Orange Unk. Prehisp. Orange Orange Orange Orange Orange Unk. Prehisp. Orange Orange Orange Orange Orange Unk. Prehisp. Unk. Prehisp. Unk. Prehisp. Unk. Prehiso. Orange I Orange Orange

FS no. =field sample number, FtM = Ft Mose, FOY = Fountain N= number of otoliths, x = mean otolith length. * = Late 17th and 18th century. t = 16th and early 17th century. Values for otolith size range and screen size are in mm.

undulatus Screen

size

6.35 6.35 6.35 1.59 I.59 1.59 1.59 1.59 1.59 1.59 I.59 I.59 I.59 I.59 1.59 I.59 I.59 1.59 I.59 I.59 I.59 I.59 1.59 I.59 1.59 1.59 I.59 1.59 1.59 I.59 1.59 I.59 1.59 I.59 1.59 of Youth

Park,

To save otoliths needed for other studies, not all otoliths were sectioned. Size distributions of sectioned and non-sectioned otoliths were compared by the Mann-Whitney U procedure (Zar, 1974). Usually, sectioned and non-sectioned otoliths had similar size distributions (U,,, = 3780, P=O.l 1 for Mission Period; and U,, =450,5, P= 0.07 for Unknown Prehispanic Period), but sectioned and non-sectioned otoliths had different size distributions for the St Johns IIc Period (U,,,,, = 160, P = 0.02). Thus, age distributions presented for all periods include both observed ages and age estimates generated from a theoretical growth curve (described later in Methods and given in Results). Because otolith size distributions were not normally distributed and sample sizes were seldom equal, non-parametric tests were used to compare otolith size distributions (Zar, 1974). The Mann-Whitney test was utilized to compare the following otolith length distributions: Prehispanic versus First Spanish Period collections, Contact versus Mission

HISTORICAL

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79

(a)

Figure Atlantic in this lucent of one indicates

2. (a) Photograph of a frontal section through a 16.5 mm otolith of an croaker, viewed with transmitted light. Ten opaque increments are visible view. (b) Diagram of the above photograph, identifying the core, a transincrement, and an opaque increment. The annual growth pattern consists transluscent increment and one opaque increment (=annulus). The bar I mm.

collections, Orange versus Unknown Prehispanic Period collections, and St Johns IIc versus all other Prehispanic Periods combined. The Kruskal-Wallis test (Zar, 1974) was used to compare otolith size distributions of Prehispanic (Orange, St Johns IIc, and Unknown Prehispanic) and First Spanish Period (Contact and Mission) collections. Analysis of marginal increments (Bagenal & Tesch, 1978) was performed to determine the season of collection (time of fish death). The marginal increment, the distance from the

L. S. HALES

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outermost annulus to the otolith edge, was measured and computed as a percentage of otolith length. These percentages were then averaged for each collection. In addition, the percentage of otoliths having an annulus on the outermost edge (= % opaque otolith margins) was plotted for each archaeological sample to determine the season when fish were caught. To estimate Atlantic croaker size from otoliths, OL and total fish length (the distance from the tip of the jaw to the end of the caudal fin, abbreviated as TL) was measured from 96 modern Atlantic croaker (1540 cm TL) collected in Georgia (N= 15) and Virginia (N= SO). Otolith morphology, though species-specific (Chao, 1978; Harkonen, 1986), may vary among populations (Casselman et al., 198 1); therefore, F,,,,, tests (Snedecor & Cochran, 1980) and analysis of covariance (Zar, 1974) were used to evaluate differences in otolith morphology due to otolith location (left or right) and sample origin (Georgia or Virginia). Samples from Georgia and Virginia were used because of their availability. The relationship determined from these specimens was assumed to hold for archaeological material, even though some otoliths in archaeological collections were larger than those obtained from modern sources. Unfortunately, otolith measurements could not be obtained from the largest reported specimen of Atlantic croaker (Rivas & Roithmayr, 1970), because the specimen was lost in a recent hurricane (C. Roithmayr, pers. comm.). The OL-TL relationship was used to back-calculate total length at earlier ages using the proportional method (Bagenal & Tesch, 1978). Mann-Whitney and Kruskal-Wallis procedures were used to compare back-calculated sizes at age. A von Bertalanffy growth curve (Ricker, 1978) was fit to back-calculated lengths using the SYSTAT Nonlin procedure (Wilkinson, 1984). The growth equation is L, = L,[I - e-K(‘~‘o)]; where L, = total length at age t; L, = theoretical maximum length; K=growth coefficient; and t, = time when length theoretically equals zero. The assumption of normality was tested by examining the residuals about the regression (Sokal & Rohlf, 1981). The von Bertalanffy curve was then compared with other published studies (Music & Pafford, 1984; Barger, 1985; Ross, 1988). Size frequency distributions were then plotted for the estimates of TL determined from the OL-TL regression and compared with published size frequency distributions (Bearden, 1964; Music & Pafford, 1984; Ross, 1988) in which M. undzdatus were captured by different methods in various estuarine locales. These comparisons were made to ascertain possible methods and locations of capture. Results A total of 415 otoliths (6.2-19.5 mm OL) were obtained from 35 samples excavated from the two sites (Table 1). The size of the smallest otoliths collected in all samples was not significantly correlated with screen size (Spearman rank correlation, ys= -0.016, P=O.93). Otolith

size distributions

Otoliths ranged widely in length, from 6.2-l 7.4 mm and from 6.7-I 9.5 mm for Prehispanic and First Spanish Period collections respectively. Size distributions tended to be bimodal or multimodal within most periods. Otolith length distributions (Figure 3) differed between First Spanish and Prehispanic collections (Mann-Whitney test, U,,, = 29,583, P=O.OOOl). Otoliths from Prehispanic periods were generally smaller than those from Hispanic periods (mean = 12.0 and 13.9 mm respectively, standard deviation = 2.3 for both). Possible bias introduced by different screen sizes will be addressed below. Within both Prehispanic and First Spanish Periods, there was remarkable consistency in the distributions of otolith length (Figure 3). Contact and Mission Period collections of the FSP had similar distributions (Us,*= 7608.5, P= 0.86), with identical means (13.9

HISTORICAL

CHANGES

-5 30

10

IN ATLANTIC

15

CROAKER

81

20

Contact Period N = 77, x = 13.9, s.E.= 0.28

N=67,

Orange Period Y= 11.9, s.c’O.22

Unk. Prehlspanic N=61, x=12.4,

5

IO Otolith

length

Period x=0-23

I5 (mm)

20

Figure 3. Frequency distributions of otolith length for Mission, Contact, St Johns Ilc, Orange and Unknown Prehispanic Periods. N= total sample size. x=mean OL, and SE. =standard error of OL.

each) and standard deviations (2.2 and 2.4, respectively). With the exception of one small collection (FOY 1053) of small otoliths from a Mission sample (Table l), distributions of otolith lengths were similar within all First Spanish period samples (Kruskal-Wallis test, H 4,267= 5.50, P = 0.24). Distributions among Prehispanic Periods which spanned nearly 3200 years (compared to only 300 of the FSP) were also similar (H, ,49= 2.06, P= 0.36) with mean otolith length ranging from 11.3-12.4 mm. Further examinations of OL distributions within Prehispanic Periods generally suggested similarity of otolith size distributions among these periods (see Results above). OL distributions among samples within the Orange Period were similar (HI,,,,= 16.7, P= 0.40), but OL distributions

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within St Johns IIc (H,,,, = 16.6, P = 0.001) and Unknown Prehispanic (H,,h, = 16.46, P=O.O2) collections were different. The difference within the St Johns IIc samples was attributable to a single sample (FOY 318). The difference among Unknown Prehispanic samples, which have similar means and ranges but contain more specimens per sample than Orange Period samples (Table l), is believed to reflect the archaeological truism that smaller samples (= deposits) usually can be dated more precisely than larger ones. Estimution and compcu+son qfjish length The equation obtained from the regression of fish total length (TL) on otolith length (OL) from modern fish samples obtained from Georgia and Virginia was TL (in mm) = 25.3 x OL (in mm)-22.7, with a high coefficient of determination (r*=0.92). Measurements were combined because no difference existed between slopes of regressions from each state (ANCOVA; F,,q, = 0.005, P > 0.50). The difference in elevations of these regressions (ANCOVA; F,,,, = 9.75; P = 0.002) was ignored in pooling the samples for a common regression; the difference was due primarily to the small sample size from Georgia (almost one order of magnitude less than the other sample) and different sizes of specimens (means = 8.5 and 13.9 mm OL respectively) from the two states. Combining data from both states resulted in a regression with a high predictive value (r*=0.92), similar to the highest from either state individually (r*=0.94 and 0.65 for Georgia and Virginia respectively). Regressions determined from left and right otolith lengths had similar slopes (ANCOVA; F, 2x= 0.106, P> 0.50) and elevations (F,,,, = 0.069, P> 0.50), so this was unimportant in estimating total length. Both adult and juvenile croaker were taken in all archaeological time periods (Figure 4). Size distributions of all periods overlapped extensively (> 70%). Large adults (TL > 35 cm) comprised a greater percentage of individuals from the First Spanish Period while nearly 30% of Orange, St Johns IIc and Unknown Prehispanic specimens were < 25 cm TL. The multimodal size distributions indicate that (1) several age classes were caught, and (2) fishing occurred in several times and places and may have used several methods within most periods. Age determinution clnd distribution Ages were obtained from 185 of 202 otoliths (6.2-19.5 mm OL) processed; the others were destroyed during grinding. Physical changes were observed in some otoliths: most were more opaque than recent otoliths, some were noticeably softer and crumbled when processed, and outer portions of some had eroded. Few had undergone changes sufficient to render internal structure different from modern specimens. The number of assumed annuli on different otoliths ranged from 0-l 5 (mean = 5, variance = 2.9). Atlantic croaker captured in the First Spanish Period ranged in age from 1-l 5 years but only individuals less than 11 years were captured in the Prehispanic Period (Figure 5). Age distributions differed among Prehispanic and First Spanish Periods (U,,, = 6365, P
HISTORICAL

30

t

CHANGES

300

400

St Johns Ilc Period N=21, x=264, s.~.=22,3

30

83

I

200

Y

CROAKER

M~ssmn Period N = 189, x =330, SE= 4.0

:$ ‘I 100

a

IN ATLANTIC

N = 67,

500

I

Orange Period x = 278, SE.= 5.6

200

300

Unk. Prehlspmc N=6l, x=291,

400 Period SE‘5.9

:$&I 100

200

300 Total

Figure 4. Frequency Johns Ilc, Orange x = mean TL, and

length

400

500

(mm)

distributions of total length (TL) for Mission, and Unknown Prehispanic Periods. N=total SE. = standard error of TL.

Contact, St sample size,

collections having similar means (6.1 and 6.0 years, respectively) and age distributions (U,(), = 1147.5, P=O.85). Fish growth Back-calculated sizes at age for Prehispanic and First Spanish Periods (Table 2) showed good agreement with observed length at age except for the youngest (age I) and oldest (ages XIIILXV) ages. Observed size at age was generally larger than back-calculated size, apparently due to growth after mark formation.

84

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Contact

Period

5 ,x30

,

IO

St Johns

15

iic Period n=IO,

/

Unk. Prehlspmc

0

I

t

Period

IO

5

N-21

15

Age (years)

Figure 5. Frequency distributions of fish age for Contact, St Johns Ilc, Orange and unknown Prehispanic collections. Dark areas indicate observed age information (n = sample size), stipled area indicates estimated age data [N= total sample size (observed+estimated)].

Some differences within Prehispanic and First Spanish Period samples were observed. Size at the five youngest ages (I-V) differed between the 16th and 18th century FSP collections (U,,, = 1587.5, P 0.50,0.44, and > 0.50 for ages III-VII respectively).

XIII

S.V.

x (weighted)

387462

XII

3

395453

XI

154 127-202 21 l-258 180-245 248-342 248-32 1 266359 283-362 283-382 248-362 305-376 311-342 306402 321-352 337453 329-387 340416

Range

390450 352-392 367425

X

IX

VIII

VII

VI

V

IV

III

+

I I 4 14 18 30 15 9 14 I 12 6 9 4 8 3 I

I

II

N

Age

Length

420_+ 38

421&26

409 * 28 372k28 396+41

128+8 238+21 226k 18 282k21 2762 17 314+31 309 k 25 324k32 307 & 38 344_+23 326+11 352f30 335&15 378 + 38 364k31 373k27

XiS.0.

at capture

206 235 25

192 23

224

228 214 222

233 222 239 235 250 230 244 225 250 218 236 219 253 242 245

2

269 21

237

251

262 244 253

278 268 285 267 278 256 283 245 262 252 285 277 270

3

292 30

267

274

286 264 274

309 297 302 283 304 268 286 272 308 300 290

4

310 29

283

295

309 283 294

323 303 324 293 309 294 327 316 307

5

327 26

299

315

331 305 308

343 319 330 315 343 333 323

6

342 27

316

334

355 324 321

347 333 360 347 339

I

356 29

333

353

374 339 339

374 357 354

8

Annulus

367 23

351

369

390 353 355

369

9

382 26

368

385

405 366 371

10

total length (mm) at agefor Atlantic croakerfrom Prehispanic (Orange+ upper value) Periods. N = number, x = mean, SD. = standard deviation

173

181

187 183 186

154 166 190 177 190 194 202 186 200 191 203 183 197 181 210 204 209

1

Table 2. Mean back-calculated Spanish (Contact + Mission;

392 22

382

401

387

I1

407 23

395

417

12

St Johns Ilc;

408 21

408

13

415 44

415

14

lower value)

455

455

15

and First

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L. S. HALES

JR. AND

E. J. REITZ I- 192 II-229 II-261 m-288 P-310 m-328 pIIJCUL-357 IX-367 X-376 Xc-384 xrr-390 xm-395 Xix-400 xr403

0

500 0 t 0 400

-

300

-

200

-

-c E c’

TL:422

,001

[I-exp(-O.lE(age+2~36))1

I 5

0

I

I IO

I

I

I

15

Age (years)

Figure

6. Von

growth curve fit to back-calculated size at age for all from this study. Predicted TL are given to the right of the figure for ages I through XV. TL = total length (in mm) at age, x = data from the northern Gulf of Mexico (Barger, 1985); (Fl), data from Georgia (Music & Pafford, 1984); (0), data from North Carolina (Ross, 1988); and(W), mean back-calculated size at age for this study (+ I S.E.). Micropogonim

Bertalanfly undulatus

Back-calculated sizes at age differed between Prehispanic and First Spanish Periods for age classes I through V (Mann-Whitney; U= 2.90, 3.24, 2.33, 2.09, and 1.87; P=O.O04, 0.001, 0.02, 0.04, and 0.06 respectively), but were similar for age classes VI through X (P=O.21, 0.53, 0.62, 0.30, and 0.38, respectively). Similarity in the older age classes is believed to be primarily due to small sample sizes, as differences in fish size were consistent throughout all age classes. The von Bertalanffy growth model provided a good fit to observed size at age data. Predicted total lengths fell within one standard error of mean back-calculated sizes at all ages (Figure 6), providing confidence in the computed relationship. The theoretical maximum length (L,) of 422 mm TL was slightly smaller than the largest individual obtained in this study, but larger than 97% of the estimated sizes of all specimens examined in this study. However, it was well-within the largest reported size of 668 mm reported for one specimen captured in the Gulf of Mexico (Rivas & Roithmayr, 1970). Atlantic croaker reached over 50% of L, by age III. Seasonality of’sh capture Marginal increments (MI) for Prehispanic and First Spanish Period collections (Figure 7) varied considerably, indicating Atlantic croaker were captured in several seasons. Otolith margins from Contact and Mission collections indicated specimen collection during or shortly after annulus formation, primarily from January through May. Collections from different Prehispanic periods showed more variation in increment formation, yet most Atlantic croaker were captured during or shortly after annulus formation. Marginal increments for Orange Period collections were similar for both FOY (0.0295 + 0.008 I mm) and FtM (0.0287 f 0.0054 mm) collections. Variation in individual collections was substantial, with mean marginal increments ranging from CO.1 1 mm,

HISTORICAL

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CROAKER

Figure 7. Marginal increments (the distance from the outermost otolith edge computed as a percentage of otolith length for averaged for each period. Values given arc the mean k 1 SE.

87

annulus to the each individual)

suggesting that croaker may have been caught year round. The St Johns IIc Period collection at FOY had the smallest MI, indicating croaker were captured during mark formation in late winter and early spring. Periodicity of annulus formation appeared unaffected by fish size or age, and no change was evident in this relationship across time. No correlation was evident between size or age of specimens and width of marginal increment (Spearman rank correlations, r,=0.058 and 0.083, P = 0.43 and 0.26 respectively), and no correlation existed between marginal increment formation and historic time (Spearman rank correlations, r,=0.564 and P = 0.26). A significant correlation might indicate progressive changes in climate or some other feature modifying annulus formation (e.g. temporal differences in fish physiology). Percentages of otoliths with opaque margins (i.e. an annulus was forming on the outer edge of the otolith) were generally consistent with the pattern of marginal increment formation (Figure 8). From 23-63% of First Spanish period collections had opaque margins, suggesting annulus formation was ongoing in all collections. For Prehispanic Period collections, high percentages (43380%) of opaque otolith edges suggest a more restrictive fishing season, primarily in winter and spring; however, percentages of opaque otolith edges in individual samples ranged from O-l OO%, with approximately one-third of individual samples at both extremes. Orange Period collections from FOY and FtM had comparable (38 and 47% respectively) percentages of opaque margins. The one St Johns TIC collection that was sectioned was apparently caught in late winter or early spring, probably from March to May, given the high percentage (80%) of opaque margins. Modern

catches by gear and location

The size distribution of Atlantic croaker varied by gear and location (Figure 9). Small croaker sizes constituted the majority of specimens caught when trawling in estuarine

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100

O-

Figure divided

I

I

8. Percentage of opaque by the number of otoliths

I

otoliths (number in the collection)

I

of otoliths with for each period.

I

opaque

edges

waters. Gill-net and hook and line catches from a variety of shallow and deep estuarine waters consisted almost entirely of specimens < 30 cm TL, comparable to the size range caught by American Indians prior to Spanish influence. Pound net catches off North Carolina beaches captured mostly large (> 30 cm TL) and only a few small (< 25 cm TL) croaker. Discussion This study is among the first to examine archaeological specimens to describe fish populations beforemoderncommercialexploitation, fishing practices by Native American peoples and changes in fishing in response to interaction with Spanish colonists. Our conclusions depend on the validity of several assumptions. Therefore, we address the assumptions before examining the results. Our assumptions involve the interpretation of marks on annuli, estimation of fish size and the amount of bias introduced at various steps in this study. Specifically, the results and conclusions of this study are based on the following assumptions: (1) opaque marks on otoliths are annuli, (2) these annuli form in the same months of the year in modern and early periods, (3) the OL-TL relationship of M. undulutus determined for modern specimens is accurate for archaeological specimens and (4) otolith collections are representative of Atlantic croaker at the time and place of capture, that is, there is relatively little bias in the capture of croaker by fishermen and their subsequent preservation and recovery. Our results and other evidence which support these assumptions are discussed below, together with the consequences of errors in our assumptions. Interpretation of’otolith increments The assumption that opaque increments observed on Atlantic croaker otoliths are annuli (i.e. the marks formed only once per year) is based on previous studies that determined the age and growth of Atlantic croaker using marks on scales or otoliths or both (White &

HISTORICAL

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CROAKER

89

Trawl (SC) Creeks and rivers

Hook and line (GA) Creeks, sounds and beaches

Gill net (GA) Sounds and beaches

26 Haul 15

L

ij

&56,

0

10

30

sefne (NC) Estuary

20 Total

30 length

40

1

(cm)

Figure 9. Frequency distribution of fish caught by different methods in different estuarine locales. Data are taken from Bearden (1964), Music & Pafford (1984). Ross (1988). States from which the data originated are South Carolina (SC), Georgia (GA), and North Carolina (NC); other abbreviations are as in Figure 4.

Chittenden, 1977; Music & Pafford, 1984; Barger, 198.5; Ross, 1988). Barger (1985) used marks on otoliths to estimate age and growth of Atlantic croaker from the northern Gulf of Mexico. The annual nature of these otolith marks could not be established by preferred methods, such as mark-recapture experiments or rearing studies (Hales, 1989); however, the relationship between fish length and otolith length was strong and marks were visible on the edge of otoliths during only one time per year. Music & Pafford (1984) usually found only one mark per year on otoliths, although two marks were occasionally seen on scales from the same individuals collected in Georgia. Studies using scales have reported different numbers of marks per year. White & Chittenden (1977) found two marks annually on scales in the Gulf of Mexico, whereas Ross (1988) reported only one mark

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annually on specimens collected in North Carolina waters. Although the period of mark formation may vary among structures, annuli on scales and otoliths have been reported to form synchronously from March through May (Music & Pafford, 1984). Thus, our assumption that opaque increments form annually is consistent with most published studies (Music & Pafford, 1984; Barger, 1985; Ross, 1988). Although the temporal periodicity of formation of opaque increments cannot be determined by the stringent criteria preferred in modern age-growth studies (Hales, 1989), additional information supports the conclusion that these increments are annuli. First, back-calculated and observed size-at-age show good agreement (Table 2). Second, the von Bertalanffy equation (Figure 6) is comparable to those previously reported. Finally, differences among growth rates and other aspects of the biology reported here are consistent with differences observed in other comparisons of modern and archaeological populations (e.g. studies cited by Casteel, 1976) and similar to changes reported between unexploited and exploited fish populations (e.g. Harris & Grossman, 1985). The assumption that opaque increments (here assumed to be annuli) formed at the same season (late winter through early spring) during these early periods and modern times is not only critical to our assessment ofwhen fish were caught, but also an important feature of our age determination. For example, the season of annulus formation directly affects back-calculation of size-at-age. Differences among published studies suggest that annulus formation is related to water temperature. Annulus formation (either for scales or otoliths) was March to June in the western Gulf of Mexico (White & Chittenden, 1977) January to May in the northern Gulf of Mexico (Barger, 1985) March through May in Georgia (Music & Pafford, 1984) and April through July in North Carolina (Ross, 1988). FOY 306 (the 16th century Contact collection) consists of specimens dated to the 6 months (September 1565 through to April 1566) that Menendez occupied the FOY site. Not surprisingly, the margin of most otoliths (64%) from this sample was opaque. Consistent with this observation, marginal increments from this collection were relatively small (mean =0.0129 mm). Size and age distributions of croaker in this collection also support the archaeological identification of this sample as material from the Mentndez occupation: specimens are older and larger than those obtained from Prehispanic periods. Similarity of the period of mark formation between this collection and modern specimens suggests that the opaque increments form at approximately the same season across these time periods.

Sources ef bias and error

Error was introduced by our procedure of estimating fish length from the allometric relationship between fish and otolith size; however, we believe this source of error to be unbiased and relatively inconsequential. Because otoliths of M. undulutus are large compared to body size (approximately 1: 23324 in length), they are excellent structures from which to estimate fish size (Harkonen, 1986; Wheeler & Jones, 1989). Estimation of the length of Atlantic croaker from otoliths increases uncertainty about size and growth comparisons; however, the 95% confidence interval around the length estimates is + 1 cm. Thus, the procedure used to estimate length from otolith size introduced relatively little error (6.5-2.2% error for fish from 15546 cm TL) in size estimates. Because the percentage error changes little over the size range, little bias was introduced by the procedure used in this study (Sokal & Rohlf, 1981). In addition, examination of the residuals of the plot of fish length on otolith length revealed no relationship between the variance in fish length and the size of otoliths. Results and conclusions of this study are also dependent upon the examined material being a random sampling of Atlantic croaker from the local population(s) during these

HISTORICAL

CHANGES

IN ATLANTIC

CROAKER

historic periods. Three processes affect this: fish capture; subsequent processing, disposal and preservation; and archaeological excavation. For the results of this study to be valid, the material must be representative of Atlantic croaker and not consistently biased by fishing gear, method, other processing activities and acculturation. In addition, later preservation and recovery must not bias archaeological collections in any size or agespecific manner. Bias, depending upon its specific source, is most likely to compromise our biological (as opposed to archaeological) results and conclusions. However, our archaeological interpretations are dependent upon an accurate assessment of Atlantic croaker biology. Thus, bias which affects biological results and conclusions also compromises many archaeological interpretations. We will examine potential sources of bias in the order that we believe they affected our results. Alkaline soils produce little degradation of bone and other calcified structures (Wheeler & Jones, 1989). Consistent with this observation, the material recovered from the coastal sites was in remarkably good condition, exhibiting relatively little deterioration. Only a few broken otoliths were recovered from either site, and no otoliths were scored or marked in any way, indicating that such structures were not used for other purposes (medicinal, decorative, etc.). In addition, numerous other bones of Atlantic croaker were also recovered at these sites. Thus, we have no evidence that hydrogeologic processes (e.g. mineralization, leaching, etc.) and cultural habits (e.g. fish processing, trade, and disposal, etc.) introduced any significant bias with regard to fish size or seasonality, as has been observed with some fish remains at other sites (Chaplin, 1971; Colley, 1986; Prummel, 1986; Wheeler&Jones, 1989). Although recovery of otoliths with different size mesh (1.59 and 6.35 cm) did not appear to grossly bias comparisons among samples between Prehispanic and First Spanish Periods, use of two screen sizes did introduce some bias and limit some comparisons between Prehispanic and FSP collections. While small screen samples contained the full range of remains from large and small croaker, large screen samples undoubtedly contained reduced numbers of smaller otoliths, limiting some comparisons due to bias among younger age classes (e.g. differences in back-calculated size at age of youngest age classes). Although the smallest size class of otoliths did differ between screen sizes, we believe this bias contributed relatively little overall to the observed differences in our study for several reasons. Otoliths of Atlantic croaker are large: the youngest age class M. undulutus were represented in samples sieved with both large- and small-meshed screens. The size at which otoliths were most abundant showed little difference between the 1.59 and 6.35 mm screens (12 mm versus 13 mm otolith size classes respectively). The most significant differences among these samples from the different periods pertain to the abundance of large, old croaker, a finding which cannot be due to use of different screen meshes because both screen sizes retain large otoliths equally well. Although use of different sizes or large (6.35 mm) screen meshes have been major sources of bias and error elsewhere (Reitz & Quitmyer, 1988) we believe that the bias introduced during otolith recovery for this study is minor and does not affect most findings significantly. Lastly and perhaps most importantly, many details affecting the actual capture of fish may bias these results. All fishing gears and methods have some inherent bias, and the location of capture affects catch composition in many ways, particularly fish size, age and sex. Because we know very little about the details of fish capture (other than season), our results can be biased in many ways, especially: (1) by the gears and methods of capture selecting for different size classes; (2) by size-dependent habitat use by fish or fishing locations varying seasonally or annually; or (3) by changes in croaker population(s) over time, especially those which affect size structure and growth rates (e.g. population size affecting growth rates, Botsford, 1981). These factors can result in bias that significantly affects our results; however, analyses of data from the many otoliths (N= 415) recovered

92

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at these sites (FOY and FtM) are largely consistent and (except for some noted bias) suggest that such bias is minimal with regard to the reported findings. Otolith size and age distributions Bimodal and multimodal distributions of otolith sizes suggest that Atlantic croaker were caught by different gears in various places. Consistent differences in the size distributions between Prehispanic and First Spanish Period collections suggest that Spaniards had access to gears that were selective for larger fish, fished in places preferentially occupied by larger fish, or both. Most fish caught during the Prehispanic Period were I 29 cm TL and 4 years of age, whereas most fish taken during the FSP were larger and older. Although the abundance of small fish is undoubtedly underestimated due to the use of larger screen mesh to recover Contact and Mission collections, the absence of large individuals from Prehispanic collections indicates that Indians probably did not have access to or a means to catch large fish. Growth ofAtlantic croaker Growth of Atlantic croaker was remarkably similar during the Prehispanic and First Spanish Period. The only noted differences in size of young fish (age classes II-V) between time periods suggest more rapid growth rates of age classes II-V during the First Spanish Period. This difference resulted at least partially from use of two screen meshes during archaeological excavations; however, different gears, seasons, or fishing locales could also have contributed to the reported differences. Even with the known bias, the difference in size-at-age during these periods was generally less than 10%. Comparisons of different measures of fish growth provide considerable confidence in the reported growth rate. First, with the exception noted above, growth was similar across most time periods. This in itself is surprising given the possible time span (3200 years +) from which specimens were obtained. Second, similarity in observed and back-calculated size-at-age indicates no consistent bias in the fish catch. This lack of bias provides additional confidence that the reported growth rate accurately represents the growth of Atlantic croaker during these periods. Third, most values reported for the von Bertalanffy growth equation, though different, are comparable to modern values reported for this species (Music & Pafford, 1984; Barger, 1985; Ross, 1988). All of these comparisons suggest that our observations or estimations of size, age and growth of Atlantic croaker are accurate and relatively unbiased. Suhsistence,fishing strategies: seasonality and location In the absence of biological evidence, many archaeologists working with material from coastal sites have assumed their occupation was restricted to single seasons (Larson, 1980: 225-6; Crook, 1984) and that fishing made a limited contribution to the diet (Leach & Anderson, 1979). However, remains of Atlantic croaker and other species [other drums (Pogonias chromis, Leiostomus xanthurus, Menticirrhus spp., Sciuenops ocellatus, Stell@ lanceolutus and Cynoscion spp.), catfishes (Ariopsis felis and Bagre marinus), sheepshead (Archosargus probatocephalus), and mullet (Mugil spp.)] recovered at FOY and FtM suggest that fishing contributed significantly to the diet of Indians prior to European contact (Reitz, 1988). Detailed examination of otoliths from individual Prehispanic collections showed considerable variation in fish size and seasonality of capture, indicating Indians fished at different times and places in the estuary. This evidence conclusively indicates fishing was a prominent activity and provided considerable food to the diets of coastal Indian tribes occupying these sites.

HISTORICAL

CHANGES

IN ATLANTIC

CROAKER

Size and age distributions of Atlantic croaker from FOY and FtM suggest American Indians fished widely throughout the estuary. Small, young croaker (ages 0 and I, TL < 19 cm) from St Johns IIc and other collections were undoubtedly caught within estuaries, which Atlantic croaker preferentially occupy during their first year of life (Bearden, 1964; White & Chittenden, 1977). Atlantic croaker move to deeper estuarine waters during their first year (Yakupzack et al., 1977; Knudsen & Herke, 1978; Kobylinski & Sheridan, 1979), at which point their use of different habitats becomes less certain. Less information is available about the movements of adult croaker, and some geographic variation is apparent. Prior to the arrival of Spaniards, it is unlikely that fishing occurred in nearshore coastal waters outside of the Matanzas and North River estuaries. Old ( > 8 years), large (> 35 cm TL) croaker were rarely caught: such fishes move offshore to spawn in fall, when few if any croaker were caught. Distributional data from other geographic areas indicates larger croaker are frequently found outside of estuaries in coastal waters (White & Chittenden, 1977; Barger, 1985; Ross, 1988) although they often enter estuaries in spring upon their return from offshore spawning. The absence of nearshore coastal species (e.g. black sea bass, Centropristis striata; sand perch, Diplectrum formosum; and the mackerels Scomheromorus cavalla and S. maculatus) and the extensive number of estuarine species (e.g. sea catfish, Ariopsis ,felis; spot, Leiostomus xanthurus; silver perch, Bairdiella chrvsoura) recovered in these and other coastal zooarchaeological collections (Reitz, 1982, 1985, 1988, 1991) further support the conclusion that Indian fishing concentrated mostly if not entirely within the estuary. Marginal increment formation and the percentage of otoliths with opaque edges provided consistent information about the seasonality of croaker catches by American Indians. It appears that most fishing for croaker was concentrated in late winter and spring on adult croaker that had returned to estuaries after spawning offshore. Because variation in individual samples was substantial, some croaker may have been caught throughout the year. However, the high percentage of opaque otolith edges suggests a more restrictive fishing season, primarily in winter and spring. Because Atlantic croaker migrate offshore in fall to spawn in late fall and early winter, their absence from the catch may not reflect fishing effort expended by Indians during all seasons. Fishing near estuaries, especially around inlets and along beaches, is usually excellent in fall for many species (Helm, 1972) which have been recovered consistently at several archaeological sites (Reitz, 1988, 1991; Reitz & Quitmyer, 1988). Thus, interpretations that humans occupied estuarine locations seasonally should not be based entirely on the catch of croaker, which are themselves seasonal residents of estuaries. Examination of the fishes from archaeological sites may provide additional information regarding Indian use of coastal habitats and estuarine resources during other seasons. Resources in estuaries are abundant and diverse but not without their own seasonality and periodicity; thus it is not surprising that human use observed in this study and others (Akazawa, 1980; Claassen, 1983) follows a similar pattern. Use of coastal resources throughout much of the year, while taking advantage of seasonal abundances, is also consistent with information about Indian tribes of the south-eastern U.S.A. and in other countries. Using analogous techniques on mollusc shells, Claassen (1983) concluded that clams (Mercenaria sp.) were utilized by coastal Indians from late fall through late winter or spring. Other studies (Quitmyer et al. 1985; Lightfoot & Cerrato, 1989) report shellfish harvesting was year-round. Quitmyer et al. (1985) found that clam use varied among sites within a south-eastern estuarine system; during some time periods clams were harvested throughout the year while during other periods they were harvested primarily in spring or fall. Like these studies in the U.S.A., Akazawa (1980) also found occupation of coastal sites throughout much of the year 5000&8000 years ago in Japan.

94

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Influence of Spanish colonization on$shing strategies Similarity in the fauna1 remains at archaeological excavations have led to suggestions that Spanish and Indian groups used similar resources but exploited either different areas of the estuary or employed different methods to capture them (Reitz, 1985). Differences in the size and age distributions ofAtlantic croaker caught by Indians and Spaniards further substantiates this claim; however, it is difficult to distinguish if either or both occurred. Old, large croaker occur widely in coastal and estuarine waters (Barger, 1985; Ross, 1988; Snyder & Burgess, 1988). Habitat use and movements of large, old croaker are not wellknown, and geographic differences in the biology of M. undulatus do exist (White & Chittenden, 1977; Ross, 1988). The Contact Period collection, caught in a few months during 1 year by Menlndez and his colonists, indicates fishing in areas previously unexploited by Indians or use of different gears and methods. This pattern of exploitation evidently continued in the Mission Period collections, which consisted of a large percentage of old, large fish. However, young, small croaker continued to form a significant portion of the catch in the First Spanish Period; thus, fishing did not change entirely but expanded into deeper coastal waters or included a greater variety of gears. Such an expansion into a new habitat may have involved acculturation on the part of Spanish or Indian fishermen, including some sharing of methods or gears that could be used in deeper waters. Methods by which fish were caught by American Indians are not well-known, but it appears that Indians probably used several different methods, some of which were probably restricted in their application in different estuarine habitats. One of DeBry’s illustrations of fishing in Virginia (Rostlund, 1952: 100; Fundaburk, 1958: plate 54) documents Indians fishing with barrier-like devices, resembling tidal weirs in their perpendicular placement to shore, near inlets in sheltered waters behind islands. Such devices could have captured adult croaker on their offshore spawning migration in fall and their return into estuaries in spring. The abundance of small spot, mullet, and some other estuarine fishes (Reitz, 1988) suggests that Indians may have scavenged tidal creeks at low tide or diked small creeks. Both methods may have been applied in late winter and spring when juvenile croaker are abundant in shallow waters. Some information is available about fishing methods employed by Spaniards in the New World. Historical information documents that cast nets were used by Spanish fishermen in Florida waters (Garcia, 1902: 202-3) as were chinchorro and atarraya nets (AGI Contaduria 422, 1566; AGI Justicia 1001, 1569) and wiers (Garcia, 1902: 202). Given the ineffectiveness of these devices in obtaining demersal species in deep waters, it seems likely that other methods were used to catch croaker in deeper waters. One unusual difference apparent in the recovery of zooarchaeological materials is the paucity of Atlantic croaker in the St Johns IIc collection. This period was characterized by Spanish explorations throughout much of Florida, perhaps accompanied by disease. During the same period, agriculture was becoming more widespread among native Indian tribes (Newsom, 1987). Whether or not this lack of fish material from these sites can be attributed to either of these factors is not known. No comparative data are available for the St Johns TICPeriod. Changes in the biology of Atlantic croaker over Historic time The biology of Atlantic croaker appears to have changed remarkably from the Orange Period to today. Size and age structure of Atlantic croaker have changed remarkably and in a manner predicted for populations experiencing increased rates of exploitation. Nearly 40% of the population from Contact and Mission samples of the First Spanish Period are older than the oldest previously-reported age of Atlantic croaker (7 years, by Barger, 1985; Ross, 1988). This difference is more extraordinary considering that today most

HISTORICAL

CHANGES

IN ATLANTIC

CROAKER

95

Atlantic croaker in the South Atlantic Bight (Cape Hatteras, North Carolina to Cape Canaveral, Florida) do not attain 25 cm TL or reach 2 years of age (Wenner & Sedberry, 1989). Although not measured directly, this “old” age structure implies substantially lower mortality rates than those reported today for this species (Ross, 1988). Equally noteworthy are differences in the pattern of growth of M. undulutus during modern and earlier periods: growth of the youngest age classes (I-3) appears similar, but growth of the older age classes reported here is the slowest on record (Music & Pafford, 1984; Barger, 1985; Ross, 1988). Such a slow growth rate among the abundant, older age classes(which presumably share deeper habitats) may indicate its density-dependence, not usually reported in estuarine fishes. We believe the differences in the biology of Atlantic croaker reported here offer insight into several current issues. Observed differences in the biology among populations of marine and estuarine-dependent fishes in the Gulf of Mexico, South Atlantic Bight, and Mid Atlantic Bight (Gunter, 1950; White & Chittenden, 1977; Geoghegan & Chittenden, 1982; Ross, 1988) have been attributed primarily to temperature (Gunter, 1950; White & Chittenden, 1977). Although not widely examined, genetic control of observed differences (e.g. size, age, nursery recruitment etc.) has not been observed (Sullivan, 1986). If the environmental explanation is correct, it suggests one (or more) of the following changes may have occurred in the life history of Atlantic croaker: (1) the size at which croaker spawn has decreased over historic time; (2) spawning occurs in a different location, perhaps not as far offshore, with a subsequent increase in the survivorship of post-spawning adults; or (3) temperatures of coastal waters were cooler in the South Atlantic Bight than they are presently. Another potential explanation is that temperature is not the primary factor, and that some other agent(s) is responsible. If temperature is not a factor, then changes in age and size structure of Atlantic croaker population(s) may have resulted from fishing pressure and habitat alteration. Regardless of the agent that has produced that change, biologists would be well-advised to consider the implications of such changes in future studies of the biology of this and other fishes. Summary and Conclusions Differences in the size and age distributions of Atlantic croaker caught by American Indians before and after Spanish immigrations to St Augustine suggest specific differences in the location of fishing. Though not directly documented, such differences suggest changes in the methods used by the different cultures. Detailed information on increment formation suggests that Indians fished for Atlantic croaker primarily in winter and spring, although some fishing probably occurred in other seasons. Size-selective bias is evident in some biological parameters obtained from the different samples: such bias is a result ofthe archaeological method of collection and differences in the place and manner in which the fish were caught. The present study is the first to document changes in growth, longevity, size and age structure of any marine or estuarine fish over such a time period (approximately 3200 years). The biology of Atlantic croaker has changed dramatically since Spaniards discovered North America. Atlantic croaker now grow faster to attain similar maximum sizes, but live shorter lives. Although it is difficult to ascertain the causes, these changes are consistent with those observed in other fish populations that have experienced increasing rates of exploitation (e.g. Harris & Grossman, 1985). The difference in growth rate may also indicate density-dependence in this estuarine species. Acknowledgements We express our appreciation to J. Fraser and F. E. Williams III for permission to excavate at Fountain of Youth Park and Ft Mose, respectively. We thank those who graciously

L. S. HALES JR. AND E. J. REITZ provided the fauna1 remains: K. A. Deagan, E. E. Chaney, N. Lucetti, J. D. Merritt for FOY material and J. Marron for Ft Mose specimens. Otoliths were identified by G. Duncan, M. Frank, D. Varricchio and T. S. Young. We thank M. Kollock, C. Vest, J. Greenway, and T. S. Young for otolith processing and much-needed assistance, and L. Barbieri for providing croaker otoliths from additional specimens. T. Melton drew Figures 1 and 2(b) respectively. We thank G. Burgess, V. Butler, M. Chittenden, K. Deagan, C. Gilbert, G. Helfman, S. Ross and I. Quitmyer for their thoughtful criticisms of the manuscript. Special thanks are due to Rep. Bill Clark of Ft Lauderdale, whose diligent efforts convinced the Florida legislature to fund archaeological and historical research on the Ft Mose site. Research at FOY was supported by the Division of Sponsored Research, University of Florida and Grant no. 850300610 from the Florida Bureau of Historic Preservation to the Florida Museum of Natural History. LSH gratefully acknowledges support from the Georgia Sea Grant College Program (Grant no. NA84AA-D-00072) and the Department of Zoology, University of Georgia.

References

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