598 



Fishery Bulletin 102(4) 



Mean TW at age was also examined among states for 

 red snapper 2 to 10 years in age as above (Fig. 6B). No 

 significant differences were found between Alabama and 

 Louisiana (ANCOVA test of homogeneity of slopes, F 117 = 

 0.1; P=0.75; ANCOVA test for equal intercepts, F 1; ' 17 = 

 0.26; P=0.66 for intercepts). However, a significant 

 difference between slopes was detected when compar- 

 ing Alabama and Texas red snapper (ANCOVA test of 

 homogeneity of slopes, F 1;16 =19.68; P<0.0007; ANCOVA 

 test for equal intercepts, F 1;16 =2.74; P<0.12). The same 

 was found when comparing slopes for Louisiana and 

 Texas red snapper I ANCOVA test of homogeneity of 



Figure 3 



Marginal increment analysis of red snapper {Lutjanus campecha- 

 nus) otoliths for specimens from Alabama (n = 1985l, Louisiana 

 (n = 1864), and Texas <n = 1186>. 



slopes, F l 16 =9.62; P<0.008) but not when comparing 

 intercepts' (F h 16 = 0.64; P<0.44). 



Discussion 



Demographic variations in growth rates and in size- 

 frequency distributions may indicate the existence of 

 isolated management units of red snapper in the north- 

 ern GOM. The recreational harvests of Alabama and 

 Louisiana red snapper were dominated by individuals 

 ranging from 375 to 425 mm FL, whereas the majority 

 of Texas fish (69%) were 375 mm FL or less. It 

 was within this size range (375-400 mm FL) 

 that the significant differences in red snapper 

 among states were detected. The FL distribu- 

 tion of red snapper sampled in Texas also dif- 

 fered from those for Alabama and Louisiana; 

 there were very few large fish represented in 

 the Texas sample population, partly because 

 fishing tournaments (where larger individuals 

 are targeted) were not sampled in Texas. Signifi- 

 cant differences in TW frequencies among states 

 were also detected at approximately 1 kg (the 

 approximate weight of a red snapper 375-400 

 mm FL); 86% of Texas fish weighed 1 kg or less, 

 compared to only 27% of Alabama fish and 28% 

 of Louisiana fish in this size range. 



One factor possibly contributing to the modal 

 size class difference was the type of fishing 

 vessel used to catch the fish. The majority of 

 Texas specimens I~95 fr <) were sampled from 

 headboats; whereas Louisiana and Alabama 

 fish were obtained almost exclusively from char- 

 terboats. This is not to say that charterboats 

 were purposely excluded from the Texas sur- 

 vey. On the contrary, red snapper were sampled 

 from any and all available recreational fishing 

 parties at the three individual sampling loca- 

 tions. Differences in modal size and number of 

 red snapper caught per person onboard charter- 

 boats versus headboats may be inconsequential 

 considering that both trip types used similar 

 gear and targeted similar or the same fishing 

 locations. It should be noted however that in 

 the Texas study area, charterboats routinely 

 frequented a wider array of fishing spots (rigs, 

 hardbottom. wrecks, etc.) than did headboats, 

 which typically return to the same few rigs and 

 large structures over and over again iTolan 5 ), 

 Our von Bertalanffy growth models on 

 FL at age showed that red snapper from all 

 three states exhibit a pattern of rapid, linear 

 growth to approximately 10 years, after which 

 maximum theoretical (asymptotic) FL is soon 



Tolan, J. 2003. Personal commun. Texas Parks 

 and Wildlife Department, Resource Protection, 6300 

 Ocean Dr., Corpus Christi, TX 78412. 



