534 



Fishery Bulletin 88(3), 1990 



o 



O 200 



O MEAN 

 • MEAN 



SON 



1981 



D 1 J F M A M J 



1982 

 COLLECTION DATE 



D I J F M 

 I 1983 



Figure 1 



Mean and mean maximum o(jeyte diameters for red drum sampled 

 from both Atlantic and Gulf coasts of Florida. 



vitellogenesis occurred in August and September 1981, 

 when the study began on the Gulf and Atlantic coasts, 

 respectively (Fig. 1). Gonads were in spawning condi- 

 tion or were partially spent during September-October 

 1981. In 1982, active vitellogenesis began in August, 

 and most spawning or partially spent individuals were 

 collected in September. Mean and maximum oocyte 

 diameters declined by mid-November 1981 and by mid- 

 October 1982, indicating cessation of peak spawning 

 (Fig. 1). 



These results are consistent with the findings of 

 previous studies (Pearson 1929, Mansueti 1960, Yokel 

 1966, Jannke 1971, Sabins 1973, Peters and McMichael 

 1987). However, spawning in Tampa Bay may have 

 begun earlier than August in 1982 because larval and 

 juvenile length-frequency distributions and otolith 

 analyses of daily growth indicated that spawning had 

 begun in mid- July (Peters and McMichael 1987). Ap- 

 parently, spawning in mid-July did not occur in a large 

 enough portion of the population to be reflected in our 

 samples. Macroscopic analyses of adult gonads and 

 analyses of gonosomatic indices have suggested that 

 spawning takes place in Texas during October through 

 February (Heffernan 1977) and that spawning off Mis- 

 sissippi takes place during summer (Overstreet 1983). 



Ovarian histological features provided evidence that 

 spawning occurs in the nearshore Gulf of Mexico, in 



the vicinity of passes, and within estuaries. Ovaries of 

 females captured in all three areas displayed either 



(1) advanced oocytes with migrating nuclei or hyaline 

 oocytes released from the follicular layer, indicative of 

 an imminent spawn (DeMartini and Fountain 1981), or 



(2) atretic bodies and postovulatory follicles (POF), in- 

 dicative of a recent spawn (Yamamoto and Yoshioka 

 1964, Takita et al. 1983, Hunter and Macewicz 1985). 

 A female captured 4.8 km off the Florida Gulf coast 

 had numerous oocytes with migrating nuclei, and a 

 male from the same site had spermatozoa filling the 

 efferent duct of the testes, both of which suggest im- 

 minent offshore spawning. A large female red drum 

 captured about 7 km within the mouth of Tampa Bay 

 contained ovulated hydrated oocytes, POF, and several 

 atretic oocytes. All of these artifacts indicate that she 

 had recently spawned. Supporting the hypothesis that 

 estuaries are also used as spawning sites is the fact that 

 females {n = 4) that had POF or hyaline oocytes re- 

 leased from the follicle layer were found about 42 km 

 within Tampa Bay, 35 km south of Ponce de Leon In- 

 let in Mosquito Lagoon, and 90 km north of Sebastian 

 Inlet. 



Based on data from egg and larval collections made 

 just inside passes, most investigators have concluded 

 that red drum spawn principally in nearshore areas 

 close to channels and passes (Pearson 1929, Miles 1950, 



