FISHERY BULLETIN: VOL. 81. NO. 3 



DISCUSSION 



The initiation of gonadogenesis in blueline tilefish 

 during March and April and the termination in 

 September- October coincide with the periods of 

 rapidly increasing and decreasing photoperiods (Fig. 

 6). This is a more conservative environmental cue 

 than temperature when considering the shelf edge 

 habitat. Temperature fluctuations are not neces- 

 sarily seasonal, but also subject to cold-water in- 

 trusions from outer continental shelf bottom waters 

 and meanderings of the axis of the Gulf Stream 

 (Stefansson and Atkinson 1967). The initiation of 

 gonadal development has also been correlated with 

 photoperiod for the cooccurring red porgy, Pagrus 

 pagrus, (Manooch 1976). The protracted spawning of 

 vermilion snapper, Rhomboplites aurorubens, was 

 correlated with both photoperiod and water tem- 

 perature (Grimes and Huntsman 1980); however, 

 its occurrence over the continental shelf increases 

 its susceptibility to seasonal temperature varia- 

 tion. 



Blueline tilefish ovaries seasonally undergo a pro- 

 gressive maturation of residual stock oocytes to 

 vitellogenic state with several modes generated and 

 no sharp distinctions between residual and maturing 

 eggs. The multimodal size distribution of oocytes ob- 

 served is characteristic of fishes that spawn several 

 times during a protracted spawning season (Clark 

 1934; Warner 1975a; Grimes and Huntsman 1980). 

 Off North Carolina it appears that most C. microps 

 spawn during May-June and September-October. 

 The capture of large females (>600 mm TL) that 

 were Ripe in July and August might indicate more 

 frequent spawning by larger fish. The generally 

 larger females captured off South Carolina might 

 spawn earlier and more frequently than those off 

 North Carolina, although data supporting this con- 

 clusion are incomplete. The continuous develop- 

 mental pattern of male testes would certainly 

 accommodate protracted spawning by females. 



If local spawning is directed toward the main- 

 tenance of regional populations (Marshall 1966), the 

 production of several batches of eggs during a pro- 

 tracted spawning season should improve chances of 

 concurrence with favorable environmental con- 

 ditions. Of particular relevance to C. microps spawn- 

 ing are the influence and extent of transport of eggs 

 and larvae by the Florida Current (Gulf Stream). The 

 ridge and trough bottom irregularity off South Car- 

 olina known as the Charleston Bump causes a 

 seasonal deflection of the Gulf Stream and resulting 

 inshore southwest setting eddy currents occurring as 

 far north as Cape Hatteras (Brooks and Bane 1978). 



These are effective around the 5 0-1 00 fathom curves 

 and could be an important means of regional reten- 

 tion of eggs and larvae produced by C. microps and 

 other shelf edge inhabitants. 



Whether ('. microps are strictly prematurationally 

 or also functionally protogynous cannot as yet be 

 confirmed. Winter (between spawning periods) 

 collections are needed to determine whether tran- 

 sitional adults occur. The skewed sex ratios with size 

 and age could indicate that sex reversal occurs over 

 an extended range of ages rather than just pre- 

 maturationally. However, skewed sex ratios with size 

 could be attributable to differential growth rates, 

 which have been noted for C. microps (Ross and 

 Huntsman 1982) as well asL. chameleonticeps (Tur- 

 ner et al. 7 ) and other tilefishes (Dooley 1978). 

 Skewed sex ratios with age could result simply by 

 <50°A of the juvenile females changing sex to males. 

 Furthermore, functional protogyny is questionable 

 since 1) all males possessed solid testes, whereas 

 secondary males generally retained remnants of the 

 hollow ovarian lumen (Smith and Young 1966; War- 

 ner 1975a) and 2) the existence of 400-500 mm males 

 would have entailed their sex reversal prior to 

 functioning as reproductive females. 



Prematurational sex reversal, evidenced by his- 

 tological examination of juvenile gonads, accounts 

 for the presence of oocytes in developing testes. The 

 development of remnant ovarian gonocytes to pre- 

 vitellogenic oocytes in a testis could result from the 

 activation of estrogens, the presence of which is im- 

 plicit had there been a juvenile female stage (Brusle 

 1969; Brusle and Brusle 1975). The males with 

 residual oocytes were captured in the spring, the 

 period of maximum hormonal induction for initiating 

 gonadogenic activity (Hoar 1969). The residual 

 oocytes were previtellogenic oocytes which 1) are 

 reported to be the most resistant oocytes to resorp- 

 tion and atresia (Brusle and Brusle 1975) and 2) were 

 observed in medial connective tissue or in collecting 

 tubules and not interspersed within active sper- 

 matogenic tissue. 



The occurrence of prematurational sex reversal in 

 C. microps should indicate protogyny elsewhere in its 

 genus or family. This is possible though not yet con- 

 firmed for several related species. Atlantic goldface 

 tilefish, C. chrysops, captured off North Carolina and 

 in the Gulf of Mexico (n = 20) include 7 females 385- 



7 Turner,S.C, C.B.Grimes, and K.W.Abie. In prep. Age, growth 

 mortality and age/size structure of the fisheries for tilefish, Lopho- 

 latilus chameleonticeps, in mid- Atlantic and southern New England 

 waters. Department of Environmental Resources, Rutgers Univer- 

 sity, P.O. Box 231, New Brunswick, NJ 08903. 



566 



