McBride et al.: Nursery habitats for Elops sourus 
453 
o 1 - 25th percentile O 26- 50th percentile O 51 - 75th percentile O 76 - 100th percentile 
Figure 8 
Seasonal distribution plots for age-0 ladyfish, Elops saurus, collected in Tampa Bay, 1989-95. Catch-per-unit-of-effort data from all 
positive catches of age-0 ladyfish were plotted as four quartile classes to standardize the data among gear types; increasing symbol 
size indicates higher catch per unit of effort. Smaller-size, age-1 ladyfish were excluded by increasing the size range for age-0, as 
indicated in each plot, from spring to winter. 
part of Tampa Bay, and out into Gulf of Mexico waters 
during colder months. Ladyfish may be selecting these ar- 
eas for overwintering because such areas are less affected 
by atmospheric cold fronts. The critical temperatures for 
ladyfish survival have not been examined in the labora- 
tory, but the above field studies suggest that they could be 
as low as 10°C. Further work remains on the processes of 
habitat selection by ladyfish within estuaries. 
This description of ladyfish early life history satisfies 
the first two of three predictions for an estuarine-depen- 
dent species: 1) predictable use of estuarine habitats, 2) 
absence of fish in suitable alternative habitats, and 3) 
demonstration of a negative population impact caused by 
the loss of estuarine habitats. Age-0 ladyfish followed an 
ontogentic migration along a salinity gradient and lar- 
val stages of ladyfish were absent from Gulf beaches. The 
third prediction, that of a negative impact on the popula- 
tion by the absence of habitat, was not supported by find- 
ings in our study. We anticipated that salinity differences 
between Tampa Bay and the Indian River Lagoon might 
affect growth rates, either due to osmoregulatory stress 
or perhaps to other correlated factors. Metamorphosing 
larvae moved into both estuaries at about the same time 
(i.e. in spring) but age-0 fish attained similar lengths 
