444 
Fishery Bulletin 99(3) 
A 
B 
82°50' 82°40' 82°30' 82°20' 
81°00' 80°50' 80°40' 80°30' 80°20' 
Figure 1 
Sampling areas and locations where at least one ladyfish, Elops saurus, was collected for (A) Tampa Bay and (B) the Indian River 
Lagoon. Different symbols are used to represent collections in Tampa Bay: the bay-wide program (circles), the Little Manatee River 
program (triangles), and the Gulf Beach program (squares). Lines and letters (A-F) designate the sampling zones in each system. 
See text for further definition of zones and Tables 1-2 for details of all collections. 
the year in polyhaline and marine ( >18 ppt) waters such 
as Florida Bay, Biscayne Bay, and the Indian River La- 
goon (Low, 1973; Sogard et al., 1989a, 1989b; Tremain 
and Adams, 1995). Other studies, however, have reported 
presumptive age-0 juveniles (Harrington and Harrington, 
1961; Kristensen, 1964), older subadults (Carles, 1967), or 
both (Simmons, 1957; Roessler, 1970; Brockmann, 1974) in 
hypersaline waters ( >35 ppt). Thus, age-0 ladyfish may be 
seeking some condition other than specific salinities. 
The purpose of our study was to determine whether 
age-0 ladyfish make predictable size-specific seasonal 
movements that would identify them as an estuarine-de- 
pendent species. Because salinity is part of the definition 
of an estuary (Pritchard, 1967), a landscape approach was 
used to follow ladyfish movements with respect to salinity 
within Tampa Bay and the Indian River Lagoon. If age-0 
ladyfish select low-salinity waters, then we predicted that 
they would be found in lower than average salinity wa- 
ters for each estuary. Furthermore, if age-0 ladyfish select 
low-salinity habitats, then we predicted that they would 
be more abundant in the lower salinity areas of Tampa 
Bay because this bay has a wider salinity range to select 
than that for the Indian River Lagoon. We also examined 
length-frequency data to make preliminary assessments 
of age-class composition and growth rates of ladyfish with- 
in estuaries. Although several publications have discussed 
the ecology of ladyfish in estuaries (e.g. Springer and 
Woodburn, 1960 and citations above), to our knowledge 
the data treatment in our study is the most comprehen- 
sive for this species. 
Methods 
Study sites 
Data from Tampa Bay, on central Florida’s west coast, 
were compared with data from the Indian River Lagoon, 
on central Florida’s east coast (Fig. 1). Both water systems 
are located at similar latitudes, so they are subject to simi- 
lar temperature cycles. Both systems are positive estuar- 
ies (i.e. freshwater input exceeds evaporative processes; 
Pritchard, 1967), but they have distinctive salinity regimes 
(Fig. 2). Tampa Bay is a drowned river system with con- 
siderable freshwater input and separate satellite barrier- 
island embayments, whereas the Indian River Lagoon is 
largely a series of barrier-island embayments with few 
inlets and no major rivers (Comp and Seaman, 1985). 
Bay-wide survey— Tampa Bay We examined survey data 
for Tampa Bay fishes collected from 1989 to 1995 by staff 
of the Florida Marine Research Institute (FMRI). The sam- 
pling design incorporated both fixed sampling stations and 
locations assigned in a stratified random manner (McMi- 
chael et al., 1995). Tampa Bay was stratified into six major 
zones (Fig. 1A): the upper bay (A), the western bay (B), 
