146 



Fishery Bulletin 102(1) 



Figure 3 



Frequency distribution of spotted seatrout 

 {Cynoscion nebulosus) age classes used in deter- 

 mining minimum age at full recruitment to the 

 sampling gear, and mortality. 



32 

 30 



I 28 



CO 



ra 26 

 a> 



Q. 



E 



CO 



merited by using a generalized linear model 

 (SAS/STAT software, version 6.12, SAS Insti- 

 tute, Cary, NO to test if growth differed among 

 cohorts. A general linear test ( Neter et al., 1983 ) 

 was used to compare growth between three geo- 

 graphical subdivisions (Gulf transition, western, 

 and central). This test is a function of the error 

 sum of squares of the reduced model minus the 

 error sum of squares of the full model. Adequate 

 numbers of juveniles were not available to com- 

 pare growth in eastern and northern subdivi- 

 sions (Table 1). Circular statistics (Batschelet, 

 1981) were used to determine if spawning, as 

 determined from hatchdate distributions, was 

 uniform over the lunar month. The phase of the 

 moon for 1995 was identified by the fraction il- 

 luminated (U. S. Naval Observatory Applications 

 Department, 1997). A 3-point moving average 

 was used to test if spawning was cyclical. 



Cohorts (1995) were categorized according 

 to the following hatchdates: cohort A, 29 March-2 May 

 ("April"); cohort B, 3 May-6 June ("May"); cohort C, 7 

 June-4 July ("June"); cohort D, 5 July-1 August ("July"); 

 cohort E, 2 August-5 September ("August"); cohort F, 6 

 September— 3 October ("September"). 



Comparisons of the relative recruitment potential of 

 individual cohorts (G:M ratios) between all cohorts were 

 unresolved. Although cohort mortality estimates could 

 be generated, they were appropriate (by analyzing r 2 and 

 P-values from regression analysis) for only three cohorts 

 (cohorts B, D, and F). 



A random coefficient model was used to investigate the 

 relationship between growth rate of otoliths with age and 



24 



22 



20 - 



(I 



O 



II 



Station 



Figure 4 



Mean and ranges of temperature and salinity data by station used in 

 the otolith microstructure longitudinal analysis (relationship between 

 increment width and temperature and salinity). For station locations 

 relative to subdivisions, see Table 1 and Figure 1. 



temperature from juveniles collected in 1995. Most fish 

 were exposed to salinities in a narrow range between 28 

 and 34 ppt; only 9 fish were exposed to salinities in the 5-13 

 ppt range (Fig. 4). Consequently, there was insufficient in- 

 formation to obtain reliable inferences on the relationship 

 of growth rate to salinity or the relationship to salinity 

 and temperature for growth information obtained by using 

 either otolith measuring path. This was a disappointment 

 because growth responses to salinity were considered an 

 important objective in relation to proposed Everglades 

 water management activities. Thus, investigation was 

 restricted to the relationship of growth with temperature. 

 A separate model was fitted for the first ( 1-21 increments) 



