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FORK LENGTH (CM) 



Figure 1. — Length frequency distributions by quarters of 

 the year for wahoo sampled from a taxidermy plant in 

 south Florida from September 1967 through September 

 1968. 



Wahoo are most abundant off southern Florida 

 in winter (fig. 1). LaMonte (1951) reportedthat 

 wahoo are taken off Hatteras, N.C., from June 

 to October and are rare or absent at other 

 times. Off Bermuda a minor run occurs in 

 April, and abundance is at a peak in Septem- 

 ber and October (Mowbray, 1956). In spring a 

 large number of relatively small (96 to 105 

 cm.) wahoo appear off the lower Florida 

 coast, in summer the mode representing this 

 group of fish (July-September, fig. 1) 

 progressed slightly, indicating growth of about 

 3 to 4 cm. per month. 



Little Tuna 



Little tuna are one of the most common 

 tunas caught by sport fishermen off southern 

 Florida and are most abundant in summer 

 (fig. 2). According to de Sylva and Rathjen 

 (1961) little tuna are most abundant in the catch 

 of sport fish in south Florida from April 

 through August with a peak in June. Our 

 samples show that little tuna of 66 to 75 cm, 

 fork length are dominant in the south Florida 

 sport-fish catch throughout the year. 



Skipjack Tuna 



Skipjack tuna, which have become increas- 

 ingly important to the worldwide commercial 

 tuna catch in recent years, are most abundant 

 off Florida in fall and winter. The large mode 



in October-December (fig. 3) disappeared in 

 the next quarter although the single low peak 

 at 63 to 64 cm. may represent this group of 

 fish. The peak reappeared in April-June at 

 about 65 to 68 cm., possibly representing 

 growth of about 1 cm. per month. Brock (1954) 

 and Rothschild (1967) showed growth rates for 

 skipjack tuna in the Pacific of 1.5 to 2.0 cm. 

 per month. The dominant mode in our samples 

 in January-March disappeared in April-June, 

 and a new peak appeared at 42 to 43 cm., which 

 indicated that a number of small fish had 

 moved into the south Florida area. 



King Mackerel 



The king mackerel, a migratory species, is 

 most abundant in the winter off southern 

 Florida where an important fishery for the 

 king and Spanish mackerels is carried on- -in 

 1967 more than 750 metric tons of king 

 mackerel and 1,300 metric tons of Spanish 

 mackerel were landed (Bureau of Commercial 

 Fisheries, 1968). 



The three modes present in the January- 

 March quarter (fig. 4) suggest the presence 

 of only three age groups in the sport-fish 

 catch off southern Florida. According to a 

 study of age and growth of king mackerel in 

 Brazil by Nomura and Rodrigues (1967), how- 

 ever, the size range represented in figure 4 

 (January-March) would include their age- 

 groups IV (62 cm.) through XII (120 cm.). 

 Catches off Florida are few in summer, and 

 most king mackerel caught are relatively 

 small. 



Blackfin Tuna 



Blackfin tuna, which represent a potentially 

 valuable commercial resource in the Gulf of 

 Mexico and Caribbean Sea, are abundant off 

 southern Florida throughout the fall, winter, 

 and spring, but sport-fish catches decline 

 sharply in the summer (fig. 5). The blackfin 

 is one of the more abundant tunas in the Gulf 

 and Caribbean but is fished commercially 

 only in Cuba, where there is an active live- 

 bait fishery for blackfin and skipjack tunas 

 off the southern coast. Blackfin tuna make up 

 about two-thirds of the catch (Suarez Caabro 

 and Duarte Bello, 1961), and though peak 

 abundance is from April to July, the fish are 

 present throughout the year. In our samples 

 the first mode, in October-December (fig. 5), 

 appeared to progress from about 47 to 48 cm. 

 to about 51 to 52 cm. in April-June, which 

 suggested a growth of slightly under 1 cm, 

 per month, similar to that indicated for skip- 

 jack tuna. The second mode in April-June can 

 possibly be traced back to the large peak at 

 55 to 56 cm. in October-December, indicating 

 growth of about 1.5 cm. per month. 



