AGE, GROWTH, AND MORTALITY OF 



KING MACKEREL, SCOMBEROMORUS CAVALLA, FROM 



THE SOUTHEASTERN UNITED STATES 1 



Allyn G. Johnson, William A. Fable, Jr., Mark L. Williams, and Lyman E. Barger 2 



ABSTRACT 



Age, growth, and mortality of king mackerel, Scomberomorus en ml In, from the southeastern United 

 States were studied. Otoliths from 1,449 fish were used to estimate age composition, growth rates, 

 and mortality rates of this species. 



Age composition varied between locations (Texas, Louisiana, Florida, South Carolina, and North 

 Carolina). The majority of older fish were found in Louisiana waters. The oldest females were 14 + 

 years old and the oldest males were 9+ years old. Compensatory growth was found in both sexes. The 

 von Bertalanffy growth equations were as follows: Males (all areas) 1, =965(1 — e' ' 17) ); females 



from Louisiana 1 , = 1 ,529 (1 — e 



'); and females (excluding Louisiana) 1 ( = 1,067 ( 1 — e 



-0 291 1 -0 97) 



where 1 = fork length (mm) and / = years. The mean annual mortality rate determined by six 

 methods of analysis ranged from 0.32 to 0.42. The length-weight relations of king mackerel were for 

 males: W = 0.8064 X lO^L 29928 ; for females: W = 0.8801 X 10" 5 L 29827 . where W = weight in grams 

 and L = fork length in millimeters. 



King mackerel, Scomberomorus cavalla, is a 

 major recreational and commercial fisheries re- 

 source in the southeastern United States (Ma- 

 nooch 1979). Age, growth, and mortality informa- 

 tion has been based on small specimens collected 

 from a limited geographical area (Beaumariage 

 1973). A need has existed to reexamine age, 

 growth, and mortality from broader geographi- 

 cally based samples. 



King mackerel of Brazil have been studied in- 

 tensively, but the great distance separating these 

 Brazilian fish from those in the United States 

 makes application of their results to king mack- 

 erel in United States waters a questionable prac- 

 tice (see Manooch et al. 1978 for annotated bib- 

 liography on this species). 



A geographically comprehensive sampling of 

 king mackerel in U.S. waters was initiated by us 

 in 1977. Recreational landings were sampled be- 

 cause the sport fishery is less localized than the 

 commercial fishery. We utilized samples from 

 Texas to North Carolina to meet our objectives of 

 determining the age composition, growth rates, 

 length-weight relationships, and mortality rates 

 of king mackerel from U.S. waters. 



•Contribution No. 82-29-PC, Southeast Fisheries Center 

 Panama City Laboratory, National Marine Fisheries Service, 

 NOAA, Panama City, Fla. 



2 Southeast Fisheries Center Panama City Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, 3500 Delwood Beach 

 Road. Panama City, FL 32407-7499. 



METHODS AND MATERIALS 



King mackerel (7,723 fish) were collected from 

 Texas, Louisiana, Florida, South Carolina, and 

 North Carolina from June 1977 through August 

 1979 (Fig. 1). They were caught by recreational 

 hook and line, except for some small individuals, 

 which were caught in shrimp trawls at Cape 

 Canaveral, Fla., in December 1978. The trawl- 

 caught fish were used in determining the rela- 

 tion between otolith radius and fish length. In 

 1979, 121 fish samples were taken only in north- 

 west Florida and were used to supplement exist- 

 ing samples for the marginal increment analysis. 



Processing the fish samples involved several 

 steps. The fish were sexed when possible, mea- 

 sured to the nearest millimeter of fork length 

 (FL), and weighed to the nearest gram. Otoliths 

 were removed from the fish, cleaned, and stored 

 either dry or in 100% glycerin. 



The otoliths were examined under reflected 

 light in a black-bottomed watch glass containing 

 100% glycerin with a binocular dissecting micro- 

 scope at 28X. The otolith radius (OR) was mea- 

 sured on the posterior surface from the focus to 

 the distal margin along the axis approximating 

 the extension of the sulcus acousticus. All mea- 

 surements were made in ocular micrometer 

 units (1 om/j. = 0.0363 mm). Marks were counted 

 and measured along the radius to their distal 

 edge. The marks were opaque (light) under re- 



Manuscript accepted June 1982. 



FISHERY BULLETIN: VOL. 81. NO. 1. 1983. 



97 



