Munroe: Systematics of western Atlantic Symphurus 
as those in high energy surfzone areas (Modde and 
Ross, 1981), or on live-bottom areas (Topp and Hoff, 
1972; McCaffrey, 1981; Darcy and Gutherz, 1984) 
with calcareous sands. In saltmarshes, juveniles oc- 
cur where stem density of Spartina is low ( Rakocinski 
et al., 1992, Baltz et al., 1993). 
Symphurus plagiusa is the most euryhaline of 
North American tongueflshes, and has been recorded 
at salinities of 0.0-42.9%e (Gunter, 1945; Springer 
and Woodburn, 1960; Tagatz,1968; Roessler, 1970; 
Swingle, 1971; Topp and Hoff, 1972; Shealy et al., 
1974; Schwartz et al., 1981). Simmons (1957) indi- 
cated that S. plagiusa did not tolerate salinity much 
above 35 %c. Symphurus plagiusa undergoes an on- 
togenetic shift in habitats in relation to salinity, with 
smaller juveniles occupying lower salinity regions of 
the estuary and larger juveniles and adults moving 
into higher salinity areas (Gunter, 1945; Springer 
and Woodburn, 1960; Swingle, 1971; Ogren and 
Brusher, 1977). Baltz et al. (1993) indicated that an 
apparent ontogenetic shift in estuarine occurrence of 
the species may not be a primary response to a salinity 
gradient (see Rakocinski et al., 1992), but rather an 
ontogenetic shift to higher velocity microhabitats. 
From Chesapeake Bay and south through its range 
in the southern Gulf of Mexico, S. plagiusa is the 
most common tonguefish occurring on soft-bottom 
substrates and is a year-round resident in nearshore 
marine and estuarine waters. In fact, as Topp and 
Hoff (1972) noted, this species represents a signifi- 
cant proportion of the demersal fish community of 
nearly every major estuarine system through much 
of its range. In lower Chesapeake Bay and tributary 
rivers, Bonzek et al. (1993) recorded S. plagiusa as 
the sixth most abundant fish species overall in trawl 
surveys of primarily juvenile fishes. Here, tongue- 
fishes, 34-204 mm TL (mean size 127 mm), were 
taken every month of the year and were widespread 
at stations along lower segments of tributary rivers 
and in lower Chesapeake Bay. Average catch of the 
species was 6.5 fish/trawl, which was second in abun- 
dance only to the hogchoker ( Trinectes maculatus) 
among flatfishes. 
In coastal habitats along the southeast United 
States, S. plagiusa is also very abundant (Webster 
et al. 3 ). This species was present in all major estua- 
rine areas and coastal regions of South Carolina 
sampled during a 12-month period (Shealy et al., 
1974), where it ranked 13th in numerical abundance 
and 14th in biomass among the fishes collected. 
Shealy et al. (1974) considered it the most abundant 
tonguefish in South Carolina inshore waters, where 
various life history stages of S. plagiusa were present 
during every month of the year. In coastal waters of 
South Carolina, tongueflshes (primarily S. plagiusa) 
were reported as abundant in bycatch of penaeid 
shrimp fisheries from December to April and least 
abundant May through August and represented 2% 
by numbers and ranked 12th in weight of the 105 
species in the fish bycatch (Reiser, 1976). At 10 m or 
less in nearshore environments in the South Atlan- 
tic Bight from Cape Fear, North Carolina, to St. 
John’s River, Florida, Wenner and Sedberry (1989) 
recorded S. plagiusa as the 11th most numerous and 
the fifth most abundant species in biomass of all spe- 
cies taken during trawling. This species was wide- 
spread through the area, with occurrences at 78% of 
stations sampled and with fewer fish being taken in 
winter than for other seasons. Symphurus plagiusa 
is also listed as a year-round resident species in Geor- 
gia estuaries (Dahlberg and Odum, 1970; Hoese, 
1973). 
In Gulf of Mexico estuaries, S. plagiusa is also a 
common and abundant species (Springer and 
Woodburn, 1960; Swingle, 1971; Ogren and Brusher, 
1977; Naughton and Saloman, 1978). In inshore ar- 
eas of the eastern Gulf where live-bottom substrates 
predominate, it is less abundant. McCaffrey (1981) 
considered this species to be only an occasional com- 
ponent of the fish fauna on the inner continental shelf 
of the northeastern Gulf of Mexico. In contrast, S. 
plagiusa are considered very abundant in soft mud 
substrate estuarine environments in the northern 
Gulf ( Gunter, 1945 ). At offshore locations in the west- 
ern Gulf, Hildebrand (1955) noted that this species 
was particularly common in 14-16 m off Punta 
Morros, Mexico, but was less abundant on the brown 
shrimp grounds off Texas (Hildebrand, 1954). It was 
considered abundant in demersal fish communities 
of the southern Gulf of Mexico (Yanez-Arancibia and 
Sanchez-Gil, 1986), where it ranked 26th among the 
30 most abundant species occurring on the inner con- 
tinental shelf of Campeche Sound. 
Although catches of this species off the south At- 
lantic states and in the Gulf of Mexico are large 
enough to constitute a small percentage of industrial 
fisheries (Siebenhaler, 1952; Roithmayr, 1965; Ander- 
son, 1968), most fishermen regard tonguefish as a 
nuisance because these small, and relatively narrow 
flatfishes clog fishing nets and interfere with effi- 
ciency of the gear (Topp and Hoff, 1972). 
Symphurus plagiusa is a nondiscriminate, benthic 
omnivore. Throughout its life history, except for post 
larvae, which consume a variety of planktonic dia- 
toms (Strickney and Shumway, 1974), blackcheek 
tonguefish feed close to the substrate. Lists of dietary 
items include a variety of benthic prey items, algae, 
and sand grains (Linton, 1905; Hildebrand and 
Schroedei’, 1928; Reid, 1954; Springer and Woodburn, 
1960; Stickney, 1976). Food items recorded for this 
