152 



Fishery Bulletin 102(1) 



Birthweek 



Figure 8 



( Al Spotted seatrout {Cynoscion nebulosus) («=417) weekly 

 hatchdate distributions adjusted for mortality, including 

 moon phases (#=new moon; 0=full moon), and 3-point 

 moving average (solid line) of hatchdate distributions. (B) 

 Cumulative frequency of spotted seatrout (n=417) hatch- 

 date distributions. 



Florida Bay in this study along with early stage larval 

 collections (Powell, 2003) indicate that spotted seatrout 

 spawn between March and October (based on hatchdate 

 distributions) and that the majority of spawning occurs 

 between 27° and 35°C , with very little spawning between 

 20° and 26°C (based on early stage larval collections). 

 Spawning peaks, based on larval collections in 1994-96, 

 occurred in June, August, and September (Powell, 2003), 

 and early May, late June, and late August through early 

 September based on 1995 hatchdate distributions (this 

 study). However, Stewart (19611 reported that spotted 

 seatrout in Florida Bay spawned throughout the year and 

 that spawning peaked in spring and fall. Another larval 

 fish study in Florida Bay indicated that some spawning 

 occurs as early as February and continues into December 

 (Rutherford et al., 1989). 



Log e Body length = -1 .64 + 0.7821 (dorsal radius) 



? = 0.99 

 n = 232 



80 -i 



60 



40 



20 - 



E 



1 ' 1 ' 1 ' 1 ' ' 1 



B> 200 400 600 800 1000 1200 



Sagittal dorsal radius (microns) 



£ 80 



CO 



(7) 



200 400 600 800 1000 1200 

 Sagittal ventral radius (microns) 



Figure 9 



The relationship between sagittal otolith radius 

 and standard length (top), and sagittal ventral 

 radius and standard length (bottom) for spotted 

 seatrout (.Cynoscion nebulosus). 



Peak spawning activity of spotted seatrout is highly 

 variable (McMichael and Peters, 1989; Brown-Peterson and 

 Warren, 2001). McMichael and Peters (1989) observed two 

 spawning peaks; spring and summer. Older fish participate 

 in two peak spawning periods ( Tucker and Faulkner, 1987 ), 

 and a portion of the larger spring-spawned fish (age- 1+) en- 

 ter the spawning population during their second summer, 

 augmenting the number of summer spawning fish. 



We found that spawning activity and moon phase were 

 uncorrelated, which is not in concordance with observations 

 of McMichael and Peters (1989). They found that distinct 

 peaks in spawning (based on hatchdate distributions of lar- 

 val spotted seatrout) occurred at monthly intervals, and this 

 periodicity might coincide with moon phase. However, this 

 monthly periodicity was not observed when their data for 

 juvenile spotted seatrout were examined. Moreover, statisti- 

 cal tests were not performed on the data in their study. 



