Reproduction and Mating Behavior of
Cheilopogon melanurus off North Carolina

T.L. Casazza¹, S.W. Ross^1,2, A.M. Necaise¹, K.J. Sulak²

¹ University of North Carolina Wilmington, Center for Marine Science,
5600 Marvin Moss Ln., Wilmington, NC 28409
² United States Geological Survey, Florida Integrated Science Center,
7920 NW 71st St., Gainesville, FL 32653

Presented at the 2005 Joint Meeting of Ichthyologists and Herpetologists, Tampa, FL, 6-11 July 2005.

ABSTRACT

The reproductive biology of Cheilopogon melanurus (Atlantic flyingfish) was examined off North Carolina during summers. A spawning event, the first observation of mating behavior for this species, was recorded off Cape Fear, NC, on 19 August 2003. It was considered to be a spawning event due to: 1) unusual coloration of both sexes, 2) unusual swimming behavior of both sexes, and 3) ready release of gametes by both sexes upon capture. Female gonadosomatic indices were highest in June and July, but mature females were collected in each month (June, July, and August). The overall female to male sex ratio did not vary significantly from 1:1. Number of ova increased with increasing fish size, but the relationship was not strong. Our data indicate a spawning season of at least June through August off NC due to high female gonadosomatic indices, large egg diameters, presence of egg filaments, presence of spent females in July and August, and presence of small juveniles (≤= 25 mm) in July and August. This is the first report of pair spawning for this family.

Cheilopogon melanurus

• most abundant flyingfish collected off NC
• relatively large species, maximum size of 265 mm SL, matures at about 200 mm SL
• ranging from Gulf Stream waters off MA through Gulf of Mexico to southern Brazil

INTRODUCTION

Little is known of the biology of flyingfishes off the southeastern United States, largely because they are difficult to collect and have no economic value in this region. Nevertheless, flyingfishes are abundant in offshore waters of North Carolina and are an important ecological link in the open ocean surface waters. The few flyingfish species whose spawning behavior has been observed apparently spawn in large schools at the surface and often deposit eggs on floating substrata. Like all four-winged flyingfishes, eggs of C. melanurus are negatively buoyant but have long adhesive filaments facilitating attachment to one another, flotsam, or floating vegetation, such as Sargassum. Summer spawning was suggested for this species based largely on egg sizes, and gravid females have been reported from as early as March.

Figure 1. Collection sites for adult Cheilopogon melanurus off NC.

METHODS

• Surface waters in or near the Gulf Stream off NC were sampled for flyingfishes during summers of 1991-1992 and 1999-2003
• Specimens collected by small mesh neuston net (1 x 3 m) and dip nets at night
• SL, TL, weight, and sex determined for adult fish
• Gonads excised, weighed (to nearest 0.01g), and GSI (GW/(BW-GW) x 100) determined
• Chi-square analysis used to test for significant deviations from an expected 1:1 sex ratio
• Fecundity was determined and modal ovum diameter measured
• Mature ♀s have eggs with filaments
• Spawning behavior of two individuals was videotaped off Cape Fear, NC

SPAWNING BEHAVIORS

Plate 1. Figure 8 swimming configuration.

Plate 2. Male circling female.

PAIR SPAWNING OBSERVED

• Occurred on 19 Aug 03, off Cape Fear, NC at 2100 hr EST and lasted ~ 5 min
• Unique coloration of both sexes: pectoral fins pink with white margins, white spot at axil of each pectoral fin
• ♀ with 3 white bars encircling abdomen and not actively swimming
• ♂ swam in figure 8 configuration in front of head of ♀, coming into contact with head of ♀ every 2 seconds (Plate 1)
• ♂ circled ♀, coming into contact with head of ♀ every 2 seconds (Plate 2)
• Both specimens were running ripe upon capture
• First report of pair spawning for any member of this family

REPRODUCTIVE DATA

• Adults collected from 47 stations and constituted 18% of all C. melanurus collected
• Adults ranged from 166-257 mm SL, ♀s were significantly (p < 0.001) larger than ♂s
• Smallest juvenile was 12 mm SL, sizes ≤= 25 mm SL were well represented (Fig. 2)
• Of 140 flyingfish sexed, 63 were ♀s and 77 were ♂s and overall, sex ratios did not vary                significantly from an expected 1:1 ratio (χ² = 1.21, P > 0.05)
• ♀ GSI ranged from 0.95-27.26, mature ♀s were collected in all three months
• ♂ GSI ranged from 0.23-6.75, and majority (60%) of ♂s had a GSI ≤= 1.0
• Egg diameters ranged from 0.30-2.20 mm and long filaments were present on eggs ≥= 1.50 mm
• Ovum diameter increased with increasing GSI (Fig. 3)
• Fecundity increased significantly with fish size (P = 0.003) (Fig. 4) 

CONCLUSIONS

• First recorded observations of spawning in C. melanurus
• First recorded incidence of pair spawning in flyingfishes
• Two distinct spawning behaviors of ♂ were observed that included vigorous swimming and encircling of the ♀
• C. melanurus spawns at least from June through August off NC
• Spent ♀s collected in July and August
• These data agree with previous suggestions of summer spawning in this species
• Additional data needed to determine whether pair spawning is the only method of spawning in this species
• Atlantic flyingfish spawn at the surface; it is unknown if spawning at depth also occurs
• Requirement for floating objects for egg attachment is variable among flyingfishes
       -how important this is for C. melanurus needs further study

ACKNOWLEDGEMENTS

This research was partially funded by grants from the NOAA Office of Ocean Exploration. We would like to thank T.A. Munroe and A. M. Quattrini for helpful suggestions with this paper.

University of North Carolina Wilmington