583 



Abstract— Two halfbeak species, bal- 

 lyhoo {Hemiramphus brasiliensis) and 

 balao (//. balao), are harvested as bait 

 in south Florida waters, and recent 

 changes in fishing effort and regula- 

 tions prompted this investigation of 

 the overlap of halfbeak fishing grounds 

 and spawning grounds. Halfbeaks were 

 sampled aboard commercial fishing ves- 

 sels, and during fishery-independent 

 trips, to determine spatial and tem- 

 poral spawning patterns of both spe- 

 cies. Cyclic patterns of gonadosomatic 

 indices (GSIs) indicated that both 

 species spawned during spring and 

 summer months. Histological analysis 

 demonstrated that specific stages of 

 oocyte development can be predicted 

 from GSI values; for example, female 

 ballyhoo with GSIs >6.0 had hydrated 

 oocytes that were 2.0-3.5 mm diameter 

 Diel changes in oocyte diameters and 

 histological criteria demonstrated that 

 final oocyte maturation occurred over a 

 30- to 36-hour period and that ballyhoo 

 spawned at dusk. Hydration of oocytes 

 began in the morning, and ovulation 

 occurred at sunset of that same day; 

 therefore females with hydrated oocytes 

 were ready to spawn within hours. We 

 compared maps of all locations where 

 fish were collected to maps of locations 

 where spawning females (i.e. females 

 with GSIs >6.0) were collected to deter- 

 mine the degree of overlap of halfbeak 

 fishing and spawning grounds. We also 

 used geographic information system 

 (GIS) data to describe the depth and 

 bottom type of halfbeak spawning 

 grounds. Ballyhoo spawned all along 

 the coral reef tract of the Atlantic 

 Ocean, inshore of the reef tract, and in 

 association with bank habitats within 

 Florida Bay. In the Atlantic Ocean, 

 balao spawned along the reef tract and 

 in deeper, more offshore waters than did 

 ballyhoo; balao were not found inshore 

 of the coral reef tract or in Florida 

 Bay. Both halfbeak species, considered 

 together, spawned throughout the fish- 

 ing grounds of south Florida. 



Spawning cycles and habitats for ballyhoo 

 {Hemiramphus brasiliensis) and balao (H. balao) 

 in south Florida 



Richard S. McBride 



Justin R. Styer 



Rob Hudson 



Florida Marine Research Institute 



Florida Fish and Wildlife Conservation Commission 



100 8th Avenue SE 



St. Petersburg, Flonda 33701-5095 



E-mail address (for R. S. McBride): nchardmcbnde^fwc-Statefl-US 



Manuscript approved for publication 

 30 January 2003 by Scientific Editor 



Manuscript received 4 April 2003 at 

 NMFS Scientific Publications Office. 



Fish. Bull 101:583-589 (2003). 



Combined landings of two halfbeaks 

 species, ballyhoo (Hemiramphus brasil- 

 iensis) and balao (H. balao), constitute a 

 small but valuable bait fishery in south 

 Florida (Berkeley et al., 1975; McBride 

 et al., 1996). Both species occupy coastal 

 pelagic habitat in association with 

 coral reefs (Starck, 1968; Nybakken, 

 1997). During the 1990s two changes 

 in the halfbeak fishery occurred that 

 caused concerns regarding the exploi- 

 tation levels in this fishery (McBride, 

 2001). First, geographic shifts occurred 

 when halfbeak fishing expanded from 

 the Atlantic Ocean into the nearshore 

 waters north of the Florida Keys, an 

 area known as Florida Bay. Second, 

 changes in statewide net fishing regu- 

 lations^ created concerns that the net 

 fishermen displaced from other fisheries 

 might preferentially enter the halfbeak 

 fishery, thereby increasing halfbeak 

 fishing effort. These two changes could 

 have specific consequences on halfbeak 

 reproductive output. For example, 

 because some fishermen viewed Florida 

 Bay as a spawning or nursery ground 

 for halfbeaks, it was of interest to learn 

 exactly how concentrated spawning 

 might be in Florida Bay and whether 

 spawning occurred outside Florida Bay. 

 In addition, because halfbeak landings 

 are dominated by a single species, bal- 

 lyhoo (Berkeley et al., 1975; McBride 

 et al., 1996), it could be argued that 

 these changes in the fishery could dis- 

 proportionally affect spawning by the 

 less abundant, and potentially more 

 vulnerable target species, balao. 



Both ballyhoo and balao are distrib- 

 uted widely in the western and eastern 



Atlantic Ocean (Collette, 1965), but 

 no study has defined their spawning 

 grounds. Berkeley and Houde (1978) 

 described both species to be small (<32 

 cm fork length) summer-spawners that 

 rarely live past two years, but in terms 

 of spatial coverage, they collected fish 

 principally from the Miami, Florida, 

 area. We reviewed reports on regional 

 ichthyoplankton collections (e.g. Powell 

 et al., 1989; Limouzy-Paris et al, 1994) 

 and found that the numbers of halfbeak 

 eggs and larvae were too few for char- 

 acterizing the spawning grounds. More- 

 over, Berkeley and Houde (1978) sug- 

 gested that standard ichthyoplankton 

 survey data would underestimate the 

 abundance of halfbeak eggs or larvae 

 for three reasons. First, halfbeak eggs 

 appear to attach to vegetation; therefore 

 oblique tows may not target the appro- 

 priate habitats (i.e. benthic or floating 

 vegetation) and halfbeak eggs would 

 be completely lost if pleuston was dis- 

 carded from ichthyoplankton samples. 

 Second, halfbeak eggs hatch 8-9 days 

 after fertilization and may disperse far 

 away from spawning locations. Third, 

 halfbeak larvae hatch at 5-7 mm and 

 have pigmented eyes; therefore they 

 appear capable of avoiding plankton 

 nets. Various plankton sampling strate- 



 This referendum (s. 16, Art. X of the Florida 

 Constitution, enacted July 1, 1995) prohib- 

 its entangling nets in waters inshore of 3 

 miles on the Atlantic coast and 9 miles on 

 the Gulf coast of Florida (including Florida 

 Bay). It also prohibits non-entangling nets 

 larger than 500 fl^ (such as those nets used 

 by commercial halfbeak fishermen), in 

 waters less than 1 mile of Florida's Atlan- 

 tic coast and 3 miles of the Gulf coast. 



