FISHERY BLLLETIN: VOL. 81, NO. 4 



FORK LENGTH MM 



O 



OJ 



at 



40 



30 



20 



10 





 30 



20 



10 







if 50 



u 40 



Z 



30 

 20 



10 

 



349 749 1149 1549 



N/456 

 X ; 785 



TX. 



N=393 

 X= 1050 



LA. 



N2037 

 X725 



N.W. FL. 



J. 



20 

 10 

 



40 

 30 

 20 

 10 



13.7 29.5 45.2 61.0 13.7 29.5 45.2 61.0 



FORK LENGTH IN! 



1977 1978-79 



FIGURE 5. — Geographic variations in length- frequency distributions 

 of king mackerel, Scomberomorus cavalla, caught by recreational 

 hook and line during 1977-78 (and 1979 for south Florida). 



SIZE AT RECRUITMENT AND 



EVALUATION OF MINIMUM SIZE 



LIMITS 



Recruitment has been defined as 1) the addition of 

 new fish to the vulnerable population by growth from 

 among smaller categoreis(Ricker 1975; Royce 1972) 

 and 2) a movement of fish onto the fishing grounds 

 (Beverton and Holt 1957). For reasons discussed 



below, the latter definition appears most useful in 

 evaluating recruitment of king mackerel. 



King mackerel <400 mm (15.7 in) FL were report- 

 edly not caught in appreciable numbers in any of the 

 sampling areas in this study (Table 8). We suspect 

 that small king mackerel did not occur in our collec- 

 tions for reasons related to fish distribution, gear 

 selectivity, or both. Small king mackerel may occur 

 offshore beyond the areas where recreational and 

 commercial gill net fishermen normally fish for small 

 coastal pelagic species such as bluefish, Pomatomus 

 saltatrix, and Spanish mackerel, Scomberomorus 

 maculatus, because few king mackerel are landed by 

 these fishermen (Fable and Trent*). Whether small 

 king mackerel intermingle to a great extent with large 

 king mackerel offshore is unknown. Methods used by 

 fishermen to catch king mackerel in the offshore 

 areas (large hooks, large baits, and large mesh sizes) 

 are selective towards fish >400 mm FL. 



The size of king mackerel at recruitment into rec- 

 reational fisheries varied among areas and among 

 years within some areas (Table 8). In 1978, king mack- 

 erel were most available or susceptible to capture at 

 lengths between 600 and 899 mm FL in all areas 

 except Louisiana and northwest Florida. Most king 

 mackerel from Louisiana were between 900 and 

 1,099 mm FL, while most from northwest Florida 

 were between 500 and 599 mm FL. More king mack- 

 erel were reported at smaller sizes in Florida than in 

 other areas. 



King mackerel were fully vulnerable to the commer- 

 cial hook- and- line and gill net fishermen at lengths 

 between 700 and 799 mm FL during every year, 

 except 1969 in gill nets (Table 8). In 1969, full re- 

 cruitment to the gill net fishery occurred between 800 

 and 899 mm FL. 



The management measure of adopting minimum 

 size limits was considered by State and Federal 

 agencies responsible for managing king mackerel. 

 This measure would, however, drastically affect 

 some areas because of the nonhomogeneous distribu- 

 ion of the king mackerel stock(s). To illustrate, the 

 data in Table 8 were used to estimate the percentage 

 of king mackerel that would have been illegal to retain 

 had particular minimum size limits been in effect. For 

 example, a minimum size of 599 mm FL (23.6 in) 

 would have had a great impact upon recreational 

 fishermen in northwest Florida during 1978, because 

 about 66% of the fish caught would have been below 



"Fable, W. A., and L. Trent. 1982. The percentages of king mack- 

 erel and cero caught in the Spanish mackerel gill- net fishery. Un- 

 publ. manuscr., 13 p. Southeast Fisheries Center Panama City 

 Laboratory, National Marine Fisheries Service, NOAA, Panama 



City, FL 32407. 



718 



