FINUCANE ET AL.: REPRODUCTIVE BIOLOGY OF KING MACKEREL 



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NORTHWEST FLORIDA 



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LOUISIANA, 

 MISSISSIPPI 



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MIDPOINTS OF FORK LENGTH INTERVALS (mm) 



Figure 6.— Mean GSI plotted by midpoint of fork length interval for female king 



mackerel in each area. 



scombrus, are capable of spawning six batches of 

 eggs during the spawning season. Documentation 

 of spawning frequency and numbers of eggs pro- 

 duced will require that king mackerel be held in 

 captivity. 



Major spawning areas for king mackerel could not 

 be determined during this study because of the scar- 

 city of ripe fish. Gonad maturation data suggest that 

 spawning occurs throughout the sampling areas but 

 the magnitude of spawning and extent of spawning 

 areas are unknown. Ichthyoplankton surveys con- 

 ducted by Wollam (1970), Houde et al. (fn. 2), and 

 McEachran et al. (1980) have revealed general 

 spawning locations of king mackerel by the occur- 

 rence of small larvae (<3 mm SL). These studies in- 



dicate that spawning probably occurs over the con- 

 tinental shelf of the northwestern and northeastern 

 Gulf of Mexico. Most small larvae collected by 

 McEachran et al. (1980) were captured over the mid- 

 dle and outer continental shelf in water depths of 

 35-130 m off the Texas coast. 



No comparative fecundity data were available 

 from the southeastern U.S.; however, Ivo (1974) 

 determined fecundity for 39 fish from Brazilian 

 waters. He found great variation in fecundity for 

 fish with the same fork length. 



The fact that disjunct spawning appears to occur 

 off the Carolinas and in the northcentral and west- 

 ern Gulf of Mexico from spring through fall may sug- 

 gest separate stocks of king mackerel in these areas. 



847 



