DeVRIES and CHITTENDEN: SPAWNING TO MORTALITY OF SILVER SKATROIT 



(about 21 mm SL) at 1 mo of age for C. regalis 

 (Welsh and Breder 1923) can be extrapolated to 

 C. nothus. Size descriptions of spawned groups 

 (Table 2) were based upon major portions of spe- 

 cific frequency distributions cited: approximate 

 modes and/or mid ranges were used to describe 

 central tendency as judged best, often ignoring 

 extreme sizes. Ages when spawned groups dis- 

 appeared (Table 3) assume hatching at the be- 

 ginning of months specified in the group iden- 

 tity. Maximum life span was approximated in 



the sense of the Beverton-Holt model parameter 

 h ((Jutland 1969) following Alverson and Car- 

 ney's (1975) definition that only about 0.5 L% of 

 the catch exceeds age //. or its corresponding 



lengths. 



RESULTS 



Spawning 



Cynoscion nothus mature at 140-170 mm SLas 



Table 2.— Growth data for spawned groups of C. nothus from the Gulf of 

 Mexico off Port Aransas and Freeport, Tex. Unadjusted growth increments 

 between indicated collection dates were converted to growth/30 d and 

 plotted in Figure 7. Blank spaces in columns for modes and growth incre- 

 ments represent instances in which we consider size data (Figs. 3, 4) too 

 unclear to warrant further analysis. 



M)/8(MR) 

 M)/8(MR) 

 30 (MR) 

 20 (MR) 

 27 (MR) 



15 

 21 

 18 



10 



13(MR)/13(L) 



7(MR)/17(L) 



25 (MR)/26 (L) 



25 (MR)/27 (L) 



30 

 5 



489 



