128 
Fishery Bulletin 96(1 ), 1998 
Figure 57 
Geographic distribution of Symphurus civitatium based on material examined (dis- 
cussion of geographic distribution appears in species account). 
Collection data for specimens 
from this study reveal an absence 
of this species from the western 
Florida shelf. Only two collections 
record this species from the Tor- 
tugas region off southern Florida. 
Topp and Hoff (1972) also noted the 
general absence of this species along 
the west Florida shelf and found 
just a single record for S. civitatium 
in the eastern Gulf of Mexico (St. 
Joseph Bay; from Ginsburg, 1951). 
Neither their efforts during the 
Hourglass cruises on the continen- 
tal shelf off west Florida nor other 
studies (Moe and Martin, 1965; 
Ogren and Brusher, 1977; Naugh- 
ton and Saloman, 1978) yielded this 
species. Furthermore, Darcy and 
Gutherz ( 1984 ) reported taking only 
a single specimen during 338 10- 
min bottom trawls in 9 to 193 m on 
the west Florida shelf. 
Symphurus civitatium occurs on 
sand or silt substrates through its 
range. The geographic and bathy- 
metric distributions of this species 
apparently coincide with the distri- 
bution of terrigenous, quartzite sandy and silty sub- 
strates on the inner continental shelf. The scarcity 
of this species on the west Florida shelf and Yucatan 
Peninsula may reflect the strikingly different sub- 
strate compositions there. Along the west Florida 
shelf, Topp and Hoff ( 1972) reported that substrates 
consist of lithified sediments of cemented lime, in- 
cluding 1) nearshore deposits of cemented shell 
beachrock, 2) limestone, ranging from soft marl to 
conglomeritic and foraminiferal limestone, 3) small 
patches of living and dead coral, and 4) calcareous 
algae, primarily in depths ranging from 55 to 92 m. 
They noted that substrates off the Yucatan Penin- 
sula are similar in composition to those of the west 
Florida shelf. In contrast, in the central and western 
Gulf of Mexico from the Mississippi Delta to Cabo 
Rojo, Veracruz, where S. civitatium is very abundant, 
substrates on the inner shelf consist largely of ter- 
rigenous quartzite sands, silts, and clays delivered 
primarily by Mississippi and Rio Grande rivers (van 
Andel, 1960). Hildebrand (1954) noted that although 
this species was very common on sand substrates in 
the western Gulf region, it was not taken on the “24- 
10 grounds” where “most of the bottom is mud, some 
of it is soft mud and a small part is shell.” 
Substrate preference may affect the distribution 
of S. civitatium in coastal seas off the southeastern 
United States. The depth of occurrence ( 1 1-40 m, see 
below) for adult S. civitatium apparently coincides 
with sand-silt substrates on the inner portions of the 
shelf, and this species is absent from live-bottom 
habitats occurring at similar depths (Struhsaker, 
1969). 
The specimen of S. civitatum reported by Lazzaro 
(1977:69) from the continental shelf off Uruguay is 
neither this species nor any other of the Symphurus 
plagusia complex (Munroe, 1991). The body shape 
evident in the photograph, meristic features, and 
great depth of occurrence (183 m) indicate that the 
specimen is probably S. ginshurgi. 
Bathymetric distribution Although S. civitatium 
has been collected over a wide depth range ( 1-73 m), 
the center of abundance of adults, based on overall 
frequency of capture and general abundance, occurs 
between 11-45 m (Table 10). Approximately 98% 
(214/218) of the adult specimens examined in the 
present study were captured at these depths. The 
deepest captures were at 73 and 62 m, where a single 
fish was taken each time. It is unusual for adult S. 
civitatium to occur in shallow, inshore regions. The 
130 fish examined in this study collected shallower 
than 10 m were juveniles (22-66 mm) from North 
Carolina and Louisiana estuaries. Other studies in 
