28 



Fishery Bulletin 100(1) 



deep pond at the Florida Fish and Wildhfe Consei-vation 

 Commission's Keys Marine Laboratory in Long Key. Fish 

 were held at ambient temperatures and were fed frozen 

 shrimp and fish until satiated at least three times a week. 

 Although several permit were injected and held for vari- 

 ous periods, only one fish survived long enough to have 

 formed an annulus after the OTC injection. The otolith 

 section from this fish was examined with a compound 

 microscope (40-lOOx) equipped with ultraviolet light so 

 that the fluorescent OTC mark could be detected. 



Reproduction 



Histological sections of gonads were prepared and assessed 

 for reproductive state. Gonad samples were prepared for 

 histological examination with a modification of the peri- 

 odic acid Schiff's (PAS) stain for glycol-methacrylate sec- 

 tions and with Weigerts iron-hematoxylin as a nuclear 

 stain and metanil yellow as a counterstain (Quintero- 

 Hunteret al., 1991). 



Developmental stages of oocytes were determined and 

 oocytes were counted from histological preparations at 

 lOOx with a compound microscope attached to a digital im- 

 age-processing system. Four oocyte stages were recognized 

 in permit ovaries: primary growth, cortical alveolar, vitel- 

 logenic, and oocvtes in the final stages of maturation (Wal- 

 lace and Selman, 1981). The final stages of oocyte matu- 

 ration (FOM) included yolk coalescence, germinal vesicle 

 migi-ation, germinal vesicle breakdown, and hydration. We 

 also counted postovulatorv follicles (POFs) and PAS-pos- 

 itive melanomacrophage centers (Ravaglia and Maggese, 

 1995; Crabtree et al., 1997), which were present in many 

 ovaries. When stained with the PAS stain, these PAS-pos- 

 itive structures are brilliant purple. Melanomacrophage 

 centers are thought to be active in degrading atretic oo- 

 cytes, postovulatory follicles, and residual cells of the sper- 

 matogenic cycle (Chan et al., 1967; Ravaglia and Maggese, 

 1995). The developmental stage of at least 300 oocytes and 

 other structures on each slide was determined and count- 

 ed in arbitrarily chosen fields, and frequencies were ex- 

 pressed as a percentage of the total count. We counted all 

 oocytes that had at least 50*^* of their area visible in a field 

 before moving to the next field. 



We examined seasonal reproductive patterns by plotting 

 monthly juvenile length frequencies and monthly mean go- 

 nadosomatic indices (GSIs). Gonadosomatic indices were 

 calculated for 129 sexually mature female permit ranging 

 in length from 476 to 916 mm and for 122 sexually mature 

 male permit ranging in length from 449 to 855 mm as 



GSI = (GW / (7W - GW )) 100, 



where GW = total gonad weight <g); and 

 TW = total fish weight (g). 



Length and age at sexual maturity 



Females were considered sexually mature if vitellogenic 

 oocytes were present or if the histological sections appeared 

 disorganized, highly vascularized, and contained wide- 



spread evidence of atresia. We followed the classification of 

 Hunter and Macewicz (1985) in recognizing atresia. Most 

 immature females had small well-oi'ganized gonads that 

 contained little evidence of atresia. We interpreted the 

 widespread occurrence of PAS-positive melanomacrophage 

 centers in inactive ovaries as evidence of past gonadal 

 development, and we considered permit with regressed (no 

 vitellogenic oocytes present) ovaries that contained many 

 of these structures to be sexually mature. Males were con- 

 sidered sexually mature if testes contained evidence of 

 ongoing spermatogenesis, residual sperm, or widespread 

 PAS-positive melanomacrophage centers associated with 

 gonadal recrudescence. We estimated the length and age 

 at which 50% of the fish in the population reached sexual 

 maturity by fitting a logistic function to the percentage 

 of fish that were sexually mature and to their respective 

 lengths and ages. Regressions were performed with sex 

 as a categorical effect. If sex was a significant effect, the 

 equations were then reduced to separate sex-specific equa- 

 tions. The inflection point of the logistic curves was used 

 as an estimate of the length or age at which 50% of the 

 population had reached sexual maturity. 



Results 



Permit that we collected from waters off the Florida Keys 

 ranged from 258 to 916 mm in length (?!=308), and the 

 permit collected from the Tampa Bay area ranged from 

 65 to 812 mm in length (?j=228). Among permit that we 

 sexed, females ranged from 266 to 916 mm in length 

 (mean=617, SD=155.7, n = 187) and males ranged from 274 

 to 855 mm (mean=601, SD=145.8, /; = 166; Fig. 1). The sex 

 ratio of our sample was 1:1.1 (niale:female) and was not 

 significantly different from 1:1 {x~ test, P>0.05). Neither 

 the slopes (P=0.464) nor the elevations (P=0.063) of the 

 length-weight equations for male and female permit were 

 significantly different. The pooled length-weight equation 

 for sexed and unsexed fish was 



logi„Wr = 2.803 log,,, FL - 4.078, {n=488, 7--=0.996) 



where WT = weight in grams; and 

 FL - fork length in mm. 



Age and growth 



When viewed with transmitted light, permit otoliths have 

 opaque (dark) annuli that alternate with translucent 

 (light) zones (Fig. 2). Proceeding from the otoliths core 

 towards the otoliths proximal margin, annuli are regu- 

 larly spaced along the sulcal ridge. In some individuals, 

 the annuli are indistinct and irregular in appearance, 

 which made age estimation difficult. We considered 51 oto- 

 liths (17.3%) from permit ranging in length from 243 to 

 916 mm to be unreadable. The length-frequency distri- 

 bution of fish whose otoliths were considered unreadable 

 was not significantly different from that offish whose oto- 

 liths were considered readable (Kolmogorov-Sniirnov two- 

 sample test, Z)=0.144, P=0.32); thus, no particular length 



