736 



Fishery Bulletin 89(4), 1991 



and 0.087 (whole vs. sectioned, respectively) for fish 

 collected from Cape Canaveral, Florida, to Cape Fear, 

 North Carolina, during 1983-87 (Table 2). They con- 

 cluded, however, that whole otoliths may have provided 

 biased estimates, at least for Atlantic king mackerel. 

 Although the spatial distribution of our tagging effort 

 was similar to the geographical study area of Collins 

 et al. (1988), their collections occurred during regula- 

 tion of the king mackerel fishery. 



Comparison of our growth estimates for Gulf and 

 Atlantic king mackerel should be made with caution 

 due to our limited sample size and our reliance on 

 reported fish lengths. The Atlantic group appears to 

 exhibit a larger maximum size (L TC ) and a slower rela- 

 tive growth rate (K) than its Gulf of Mexico group 

 counterparts (Table 2). This is supported by compar- 

 ing the two regression equations of growth (Af ) vs. 

 time-at-large (At). We found that the slope for the Gulf 

 of Mexico group was significantly different (ANCOVA; 

 F 7.344, df 1, 592; P<0.01) than that observed for the 

 Atlantic king mackerel, indicating a faster growth rate 

 over the size range that were tagged and recaptured. 



Growth analyses using age-length data provide an 

 estimate of asymptotic mean length-at-age, while mark- 

 recapture data provide estimates of the maximum 

 length achieved in the population (Francis 1988). Our 

 L OT estimate for the Gulf of Mexico migratory group 

 (132.6cm) was larger than that for any individual fish 

 tagged or returned, except for one fish which was 133.0 

 cm FL; however, Trent et al. (1987) found fish as large 

 as 158.0cm FL in their work off Louisiana. These large 

 fish were females taken from what may be a year-round 

 resident population (Fable et al. 1987) which was not 

 included in our tagging efforts. Fish from the Gulf of 

 Mexico migratory group that were tagged in our study 

 would therefore be considered part of the 'small' mi- 

 gratory fish described by Fable et al. (1987). Manooch 

 et al. (1987) reported sampling fish up to 180.2cm FL 

 from the Gulf of Mexico; however, because they did not 

 provide a length distribution, the frequency of fish 

 larger than 132.6cm FL in their samples could not be 

 determined. All fish collected from both the Collins et 

 al. (1988) and our study were smaller than the calcu- 

 lated L^ values for the Atlantic migratory group. 



Annual survival rates 



Between 1976 and 1984, estimates of survival rates 

 were lower for the Gulf migratory group than those 

 observed for the Atlantic migratory group of king 

 mackerel (Table 3). Regression and maximum-likeli- 

 hood techniques yielded similar estimates of survival 

 rates for the Gulf group. Annual pooled estimates of 

 survival rates of these fish were in the range 41.6- 



46.5% (Z 0.877-0. 766/yr; Table 3). The simplest model 

 of Brownie et al. (1985; Model 3, constant survival and 

 recovery rates, independent of age) was the most ap- 

 plicable to our database for the Gulf group of king 

 mackerel, yielding a pooled estimate of 42.290 (SE 

 1.60; Z 0.794/yr). Estimates of annual survival rates 

 for the Atlantic migratory group were in the range 

 51.8-61.1% (Z 0.658-0.493/yr). 



Previous estimates of annual survival rates gen- 

 erated from age-length data compare favorably 

 with those calculated from our mark-recapture data. 

 Manooch et al. (1987) calculated instantaneous total 

 mortality estimates from age-length data for king 

 mackerel from two locations in the Gulf of Mexico that 

 overlapped with our study area (Table 3). Their 

 estimates of annual survival rates were in the range 

 48.7-60.7% (Z 0.719-0.499/yr) for king mackerel (both 

 sexes combined) in south Florida collected during 1981 

 (gillnet) and 1984 (purse seine). King mackerel collected 

 from recreational hook-and-line catches in northwest 

 Florida during 1980 yielded an annual survival rate 

 estimate of 58.3% (combining sexes; Z 0.540/yr). A 

 pooled estimate of annual survival rate for king 

 mackerel collected during 1977-79 along both the Gulf 

 and Atlantic coasts was 63.0% (Z 0.462/yr; Johnson 

 et al. 1983). 



Growth and mortality estimates generated from age- 

 length and length-increment studies must account for 

 behavioral characteristics germane to a migratory 

 species. King mackerel have been shown to have at 

 least two migratory patterns along the southeastern 

 United States; however, there is a seasonal overlap of 

 the two groups along southeast Florida that may be 

 as high as 29.4-41.8% (Sutter et al. 1991). Resident 

 populations of king mackerel may also exist in the 

 northcentral Gulf of Mexico (Fable et al. 1987) and in 

 southeast Florida waters (Sutter et al. 1991). These fac- 

 tors should be considered when designing future survey 

 strategies to describe growth and mortality rates. 



Acknowledgments 



We thank all of the FDNR personnel involved in the 

 many tagging trips and the recreational and commer- 

 cial fishermen who participated in this program. Par- 

 tial funding for this research was provided by grants 

 from the Department of Commerce, National Oceanic 

 and Atmospheric Administration, to the Florida 

 Department of Natural Resources under funding from 

 P.L. 88-309 and P.L. 99-659. We give special thanks 

 to the FMRI editorial staff. 



