McBride et al.: Spawning grounds of Hemiramphus braslllensis and H. balao 



587 



n=3 

 1542- 1547 h 



00 05 10 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 

 Oocyte diameter (mm) 



Figure 4 



Oocyte diameters for ballyhoo [Hemiramphus brasiliensis) collected at 

 different times of the day (EST). At least 300 oocytes were measured per 

 female. Sizes <0.25 mm were not measured representatively because of the 

 minimum size criteria of the image analysis software. Sunset occurred at 

 1830-1900 EST during this collection period (March-April), n = number 

 of females. 



in 25.8% of sets, over bare substrate in 9.7% of sets, and 

 above undefined hard bottom in 6.5% of sets. 



Discussion 



These detailed findings of prolonged summer-spawning sea- 

 sons, extreme iteroparity, and diel reproductive periodicity 

 are consistent with other studies of halfbeak reproductive 

 biology. Graham (1939), Ling (1958), Talwar (1962, 1967), 

 and Berkeley and Houde ( 1978) noted a protracted spawn- 

 ing season by hemiramphids during warm months. McBride 

 and Thurman (2003) examined the frequency of postovula- 

 tory follicles and reported that both species spawn daily 

 during late spring and early summer, but also that some 

 portion of the ballyhoo population spawns year-round. The 

 present study is the first to follow the diel progression of 



FOM within the family Hemiramphidae. Lunar periodicity 

 was not evident but it may have been confounded by the 

 highly iteroparous nature of both species. 



Spawning halfbeaks were distributed so widely through- 

 out the fishing grounds that no specific areas were identi- 

 fied for the protection of spawning individuals. We noted 

 interspecific differences in spawning areas, but these are 

 not necessarily related to preferences by spawning females 

 per se. Instead these differences appeared to be the result 

 of interspecific distribution patterns of adult halfbeaks in 

 general (i.e. adult ballyhoo are a more inshore species com- 

 pared to adult balao [McBride, pers. obs.] ). Because balao 

 were not found in Florida Bay, fishing in Florida Bay does 

 not affect this species. Spawning by ballyhoo was evident 

 in Florida Bay, as predicted by fishing industry partici- 

 pants, but spawning ballyhoo were also widespread along 

 south Florida's coral reef tract. Existing, albeit recent, 



