FISHERY BULLETIN: VOL. 81. NO. 4 



TABLE 2. — Numbers of king mackerel by capture gear, year and month, and area (M= male, F= female, U= sex unknown). Data obtained by the 



National Marine Fisheries Service, Panama City, Fla. 



millimeters. Length data were grouped into 100 mm 

 intervals and categorized by month, location, year, 

 and gear type. 



Seasonal differences in size were analyzed in great 

 detail in an earlier version of this paper by examining 

 length- frequency distributions by month within gear 

 type, area, and year. This detailed evaluation (20 

 figures, 10 tables, and 7 appendix tables) is available 

 upon request from the Florida Department of 

 Natural Resources (footnote 3). 



Chi- square tests were used to compare homo- 

 geneity of frequency distributions in relation to 

 month and gear type and to compare observed sex 

 ratios to a hypothetical 1:1 ratio (Simpson et al. 

 1960). 



SEASONAL DIFFERENCES IN SIZE 

 AND SEX RATIO 



Within each area along the northern Gulf of Mexico, 

 changes in mean and modal lengths between months 

 of king mackerel were generally similar (Tables 3, 4; 

 Fig. 2). Mean sizes along northwest Florida were high 

 in spring and fall and low during July or August of 

 each year, except in 1969. Mean sizes were also 

 generally lowest during the warmer months in 

 Louisiana and although the data were meager, 

 seasonal changes in size in Texas appeared similar to 

 those in northwest Florida. 



In south Florida, seasonal size changes, as evidenced 

 by commercial hook-and-line data, were only weak- 

 ly discernible. During most years, mean lengths 

 tended to be highest during warmer months. When 

 monthly means from different years were averaged 

 over 3-mo periods, the lengths were as follows: April- 

 June, 808 mm; July- September, 816 mm; October- 

 December, 769 mm; and January-March, 758 

 mm. 



Seasonal size changes along the south Atlantic 

 coast above Cape Canaveral, Fla., could not be 

 defined with any certainty because of the paucity of 

 data. In North Carolina, mean lengths of rec- 

 reationally caught fish increased from May (682 mm) 

 to June (735 mm) 1977, decreased from May (809 

 mm) to June (789 mm) 1978 and increased from Sep- 

 tember (844 mm) to October (856 mm) 1978. Fish 

 caught by commercial hook and line also increased 

 from September (804 mm) to October (836 mm) 

 1978 in North Carolina. In the South Carolina- 

 Georgia area the recreationally caught fish decreased 

 from September (895 mm) to October (811 mm) 

 1978. 



Females dominated catches from all areas in most 

 months and years (Tables 3, 4, 5). In Louisiana, 

 annual estimates of percent females were 91.9 in 

 1977 and 92.9 in 1978. In other parts of the northern 

 gulf and along North Carolina, South Carolina, and 

 Georgia, the annual estimates of percent female 



712 



