362 



Abstract.— The lack of age and growth 

 estimates and population parameters 

 for the amberjack family prompted our 

 study to describe otolith structure and 

 determine size-at-age and growth rates 

 of greater amberjack iSenola dumerili ) 

 from the north-central Gulf of Mexico. 

 Greater amberjack age and growth 

 was described from a combination of 

 external ridges and internal annuli in 

 sectioned sagittal otoliths. A mark-re- 

 capture study using tetracycline was 

 consistent with a single annulus being 

 formed each year in two- and three- 

 year-old amberjack. Tag-recapture data 

 from the Gulf of Mexico and South At- 

 lantic Cooperative Gamefish Tagging 

 Program also confirmed that a single 

 annulus increment was formed each 

 year. Ages for 597 specimens ranged 

 from young-of-the-year to 15 years, and 

 all fish over 9 years were female. Sag- 

 ittal weight provided a reliable estima- 

 tion of fork length with a relationship 

 ofFL = 151 (1 _e i-oo4(SH'+i.6H). g ^gga. 



tive exponential equation in the form of 

 the von Bertalanffy equation. The fit of the 

 negative exponential in this application pro- 

 vides evidence of the disassociation be- 

 tween otolith growth and fish gi-owth as 

 fish age. The von Bertalanffy growth 

 curve equation, L, = 138.9 ( 1 -e-°-^"*° ™'), 

 compared favorably with previous pub- 

 lished values. Monthly changes in size 

 and availability indicate a Gulf-wide mi- 

 gration of this moderately long-lived pe- 

 lagic predator. 



Age distribution and growth of greater 

 amberjack, Seriola dumerili, from the 

 north-central Gulf of Mexico* 



Bruce A. Thompson 

 Marty Beasley 



Charles A. Wilson 



Coastal Fisheries Institute 



Center for Coastal, Energy, and Environmental Resources 



Louisiana State University 



Baton Rouge, Louisiana 70803-7503 



E-mail address (for B A Thompson) coethoaunixl sncclsu edu 



Manuscript accepted 12 June 1998. 

 Fish. Bull. 97:362-371 (1999). 



The greater amberjack, Seriola 

 dumerili, is a pelagic reef species 

 ranging along the American coasts 

 from Nova Scotia to Brazil and oc- 

 curring throughout the Atlantic, 

 Pacific, and Indian oceans, as well 

 as the Mediterranean Sea (Mather, 

 1958; Burch, 1979; Shipp, 1988). It 

 is the largest member of the family 

 Carangidae (Hoese and Moore, 

 1977). 



Commercial landings of amber- 

 jack (all species) have increased 

 markedly over the past twenty 

 years. Landings in the Gulf of 

 Mexico peaked in 1988 reaching 2.7 

 million pounds, with a dockside 

 value over 1.6 million dollars, but 

 have since declined to less than one 

 million pounds in 1995-96. Recre- 

 ational catch statistics are incom- 

 plete but are suspected to have 

 equalled or surpassed the commer- 

 cial catch, raising concern over the 

 status of the Atlantic stock in the 

 late 1970s (Berry and Burch, 1979). 

 Despite their popularity as a recre- 

 ational and commercial quarry, 

 little is known about the life histo- 

 ries of amberjacks (Shipp, 1988). 



Of particular concern to stock- 

 assessment scientists is the lack of 

 age and growth estimates and popu- 

 lation parameters for the ambeijack 

 family (Burch, 1979; Humphreys, 

 1986). Burch (1979), using scales, 

 aged greater amberjack from the 



western Atlantic to 10 years for fe- 

 males and to eight years for males. 

 Females were significantly longer 

 than males beyond age four Hum- 

 phreys (1986) reported von Berta- 

 lanffy growth parameters for Ha- 

 waiian greater amberjack but did 

 not elaborate on how the fish were 

 aged or how many fish were con- 

 tained in the data set. 



The purpose of this study was to 

 collect and describe greater amber- 

 jack otoliths, assess their utility in 

 age estimation, and determine the 

 size-at-age and growth rates of 

 greater amberjack from the north- 

 central Gulf of Mexico. 



Materials and methods 



Sampling 



Greater amberjack («=840) were 

 collected off the Louisiana coast 

 from April 1989 to June 1992. 

 Sources of samples included a com- 

 mercial processor plant (7) = 18), 

 charterboats (n=352), saltwater 

 fishing tournaments (n =2 15), spear- 

 fishing tournaments (7! = 159), recre- 

 ational catches (n=48), and hook- 



 Contribution LSU-CFI-94-9 of the Coastal 

 Fisheries Institute. CCEER. Louisiana 

 State University. Baton Rouge. LA 70803- 

 7.503. 



