FINUCANE ET AL.: REPRODUCTIVE BIOLOGY OF KING MACKEREL 



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MALES 



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NO.FISH 2 1 2 8 89 



NO FISH 3 12 10 8 20 104 



MJ J A S O 

 MONTHS 



FIGURE 5.— Seasonal maturation cycle of male and female king 

 mackerel from area IV (North and South Carolina) shown by 

 monthly gonadosomatic index (GSI) and mean egg diameters (EDs) 

 in mm. 



(Table 2). All females were mature at 850-899 mm. 

 Another maturation pattern was noted when the 

 midpoints of fork length intervals were plotted 

 against mean GSIs for each area (Fig. 6). The size 

 interval where greatest increases in GSIs occurred 

 were 650-699 mm (area I), 700-749 mm (area II), 

 450-499 mm (area III), and 650-699 (area IV). 



Fecundity ranged from 69,000 to 12,207,000 eggs 

 in 65 king mackerel from all areas. Fish ranged 

 in FL from 446 to 1,489 mm, in TW from 681 to 

 25,610 g, and in age from 1 to 13 yr (Table 3). 

 Analysis of covariance with TW as the covariate 

 showed no significant differences (a = 0.05) in 

 fecundity between years or among areas. The best 

 predictor of fecundity based on regression and cor- 



relation analysis was TW for areas II, IV, and all 

 areas combined and FL for areas I and III (Table 

 4). Log transformed linear models were better pre- 

 dictors of fecundity than nontransformed models in 

 all areas but area IV. 



DISCUSSION 



Our results on the seasonal maturation and pro- 

 tracted spawning season of king mackerel agree 

 closely with other studies. In waters off Florida, 

 Beaumariage (1973) found late-maturing (stages III 

 and IV) eggs in king mackerel from May through 

 October. In the northeastern Gulf of Mexico (area 

 III), Dwinell and Futch (1973) caught king mackerel 

 larvae during the same time interval and MacGregor 

 et al. (1981) reported early- or late-maturing ovaries 

 from August through October. In the northwestern 

 Gulf of Mexico off Texas (area I), Finucane and Col- 

 lins (1977) and McEachran et al. (1980) noted 

 catches of larvae from May through August, and 

 April through October, respectively. In the area off 

 Cape Fear, NC, to Cape Canaveral, FL, Powles 4 col- 

 lected king mackerel larvae from May through 

 September. 



Length at maturation was difficult to determine 

 because the sample size of small fish (<600 mm) was 

 limited in all areas except area III (northwest 

 Florida). Using only fish from this area, maturity 

 first occurred about 450-499 mm and 50% of the fish 

 were mature at about 550-599 mm. These estimates 

 of maturity agreed with some of the other studies. 

 Female king mackerel first reached sexual matur- 

 ity at 630 mm and 4 yr of age (Gesteira and Mes- 

 quita 1976) or at 586 mm (Alves and Tome 1967) 

 off Brazil. Another study on Brazilian fish, however, 

 noted that females were first mature at 770 mm and 

 5-6 yr of age (Ivo 1972). In Florida waters, Beau- 

 mariage (1973) estimated that females 3 yr or 

 younger were immature and probably had not 

 spawned. He believed that the first major spawn- 

 ing by females and males occurred at 880 and 770 

 mm SL, respectively. Some of his 1-yr-old females 

 contained stage IV eggs that had been aborted or 

 reabsorbed since he did not find ripe (stage V) eggs 

 until the fish were 4 yr old. His standard length for 

 king mackerel from Florida at age 1 was 610 mm 

 (651 mm FL), which was higher than our estimate 

 of length at first maturity. 



4 Powles, H. W. Abundance and distribution of king mackerel, 

 (Scomberomorus cavalla) and Spanish mackerel (S. maculatus) lar- 

 vae of the southeast United States. Unpubl. manuscr. Gouvern- 

 ement du Canada, Peches et Oceans, Division des Sciences halieu- 

 tiques, C. P. 15500, Quebec, Canada GlK 7Y7. 



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