584 



Fishery Bulletin 101(3) 



gies could be developed to overcome these problems, but 

 we chose an alternative to plankton sampling as a way to 

 define halfbeak spawning grounds. 



B2 00' 81 30' 



&^^~ 



Atlantic 

 Ocean 



82°00*W 8r30W 8100W 80'30'W SO'OO' W 



82°0Q' 8130' 8100' 80''3Q' 80°00' 



>00 m Isobath 



Atlantic 

 Ocean 



. i">  ^ ^^ 



8200' W BV'30' W 



B2 00' 81 '30' 



00' W 80"30' W 80°00' W 

 iO'3Q' 60 00' 



Allanllc 

 Ocean 



B2 00 w erao'W eroo'W aoao'W 80"00'W 



In this study, we used collections of adult ballyhoo and 

 balao to define each species" spawning grounds in south 

 Florida. Analyses of gonad histological preparations iden- 

 tified a discrete range of gonadosomatic indices (GSI) for 

 females that were ready to spawn within hours, and the 

 locations of these fishes were plotted by using geographic 

 information system (GIS) software (Arc View, version 3.3., 

 Environmental Systems Research Institute, Inc., Redlands, 

 CA). This synthesis of GIS and GSI data was used to map 

 the spawning grounds of ballyhoo and balao. 



Materials and methods 



Sampling occurred throughout the south Florida com- 

 mercial halfbeak fishing grounds, from Palm Beach to 

 the Marquesas Keys (Fig. lA). The area immediately sur- 

 rounding Vaca Key was well sampled, but other sections 

 of the middle Florida Keys were not because commercial 

 fishermen used only six fishing ports and their day trips 

 were of limited range. Few samples were obtained from the 

 Palm Beach area because net fishing is no longer allowed in 

 much of this area (McBride, 2001). Halfbeak fishing trips 

 by commercial fishermen were monitored from November 

 1995 to April 1999 by an onboard biologist during as many 

 as four trips per month. A subsample of fish from the first 

 successful net (a lampara net) set, and occasionally from 

 later sets within a day, was obtained by filling a 5-gallon 

 bucket from the catch as it was transferred from the net 

 to holding boxes. This bucket held 100 to 200 halfbeaks, 

 and these fishes were kept on ice and brought back to the 

 laboratory for processing. 



Fishery-independent collections were made by using cast 

 nets and small hooks (sabiki rigs) in the middle Florida 

 Keys. This sampling was specifically designed to include 

 inshore areas where lampara net fishermen could not fish 

 because of regulations associated with Florida's net limita- 

 tion referendum.' The target number of these fishery-inde- 

 pendent trips from July 1997 to October 1998 was four per 

 month, and the target sample size for each trip was twelve 

 fish. Additional fishery-independent sampling occurred in 

 the springs of 1997, 1998. and 1999. 



In the laboratory, whole body weight was recorded to 

 the nearest 0.1 gram, and the gonads were removed and 

 weighed to the nearest 0.01 g. Sex was identified with the 

 aid of a dissecting binocular microscope (25-50x) when nee- 



Figure 1 



(A) Sampling area for halfbeaks {Hi'iniramphu.'! spp.) during 

 1995-99 in the Atlantic Ocean and in Florida Bay. Each symbol 

 represents an individual sample location where halfbeaks were 

 caught. Fishery-dependent samples (triangles) were taken from 

 commercial lampara net vessels. Fishery-independent samples 

 (squares) were collected in the middle Florida Keys, near Vaca Key 

 (not labeled because of the density of square symbols). Locations of 

 ripe female (B) ballyhoo (Hemiramphus brasiliensis) and (C) balao 

 (H. balao) are plotted separately. Ripe females have hydrated eggs, 

 and this condition was determined in B and C by a gonadosomatic 

 index >6.0 (see text for supporting evidence). 



