Ditty et. al: Larval development, distribution, and abundance of Coryphaena hippurus and C. equiselis 



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dolphin and pompano dolphin. Only those stations 

 where either of the two species were present were 

 included in analyses. A Kruskal-Wallis test was used 

 to detect differences among groups (a=0.05) and a 

 Tukey-type test to determine if mean differences 

 were significant (Zar, 1984; SAS Institute, 1985). 

 Dolphinfish >25 mm were excluded from analyses. 

 Temperature and salinity data were taken from 

 the sea surface only. Hydrographic data were mul- 

 tiplied by number of larvae caught (by species) at 

 each station to obtain an overall median and mean. 

 This method gives weight to distribution of larvae 

 rather than distribution of stations. We used a per- 

 cent cumulative frequency of >75% for determining 

 the relationship between distribution of dolphinfish 

 larvae and surface water temperature, salinity, and 

 station depth. Percent frequency indicates the range 

 of hydrographic conditions most often associated 

 with occurrences of larvae. Proc Univariate was 

 used to calculate median, mean, and percent cumu- 

 lative frequency statistics (SAS Institute, 1985). We 

 divided the continental shelf into approximately 

 equal geographic areas (i.e. into sq. km.) based on 

 depth and designated the inner shelf as <50 m deep, 

 outer shelf waters as those from 50 to 180 m deep, 

 and oceanic waters as those beyond the continental 

 shelf (i.e. >180 m). 



Results 



Morphology 



A continuous median finfold extended posteriorly 

 along the body of early larvae of both species from 



the posterior midbrain to the cleithral symphysis. 

 Remnants of the finfold were visible ventrally along 

 the hindgut (i.e. preanal finfold) at least through 15 

 mm. Minute epithelial spicules covered the body of 

 each species by 4 mm and were best observed on the 

 head and larval finfold. Spicules were more easily 

 observed as larvae grew. Yolk-sac larvae <3.5 mm 

 of common dolphin and pompano dolphin had 

 unpigmented eyes. Preflexion larvae (<7.0-7.5 mm) 

 of both species were elongate, with body depth usu- 

 ally <20% SL. The body became relatively deeper 

 during flexion (about 7.5-9.0 mm) and pompano 

 dolphin were deeper-bodied than were common dol- 

 phin by early postflexion (Table 1). The head was 

 moderately long (i.e. between 20 and 33% SL) in 

 both species and the snout was short and blunt. The 

 eyes were round and larger in pompano dolphin 

 than in common dolphin by early postflexion (Table 

 1). The mouth was large and oblique; upper jaw 

 length usually ranged from 42 to 45% of head length 

 in postflexion dolphinfish of both species. Pompano 

 dolphin have a larger mouth than do common dol- 

 phin by 13 mm (Table 1). The foregut was partially 

 convoluted and had a half-twist in preflexion larvae 

 of both species and a single loop in larger larvae; the 

 hindgut was straight. By 13 mm, however, preanal 

 length was generally greater in pompano dolphin 

 than in common dolphin (Table 1). Preanal length 

 usually ranged from 60 to 65% SL during preflexion, 

 but decreased thereafter to 55-60% SL in both spe- 

 cies. The pelvic fins were moderately long ( about 15- 

 18% SL; Table 1) and extend to the tips of the pec- 

 torals by 12 mm. Myomeres were obscured by heavy 



