822 



Abstract— Fecundity in striped mullet 

 (Mugil cephalus) from South Carolina 

 correlated highly with length and 

 weight, but not with age. Oocyte counts 

 ranged from 4.47 x 10'^ to 2.52 x 10^ 

 in 1998 for fish ranging in size from 

 331 mm to 600 mm total length, 2.13 x 

 105 to 3.89 X 10« in 1999 for fish ranging 

 in size from 332 mm to 588 mm total 

 length, and 3.89 x 10= to 3.01 x lO'' in 

 2000 for fish ranging in size from 325 mm 

 to 592 mm total length. The striped 

 mullet in this study had a high degree 

 of variability in the size-at-age relation- 

 ship; this variability was indicative of 

 varied growth rates and compounded 

 the errors in estimating fecundity at 

 age. The stronger relationship of fecun- 

 dity to fish size allowed a much better 

 predictive model for potential fecundity 

 in striped mullet. By comparing fecun- 

 dity with other measures of reproduc- 

 tive activity, such as the gonadosomatic 

 index, histological examination, and 

 the measurement of mean oocyte diam- 

 eters, we determined that none of these 

 methods by themselves were adequate 

 to determine the extent of reproductive 

 development. Histological examinations 

 and oocyte diameter measurements 

 revealed that fecundity counts could be 

 made once developing oocytes reached 

 0.400 nm or larger. Striped mullet 

 are isochronal spawners; therefore 

 fecundity estimates for this species are 

 easier to determine because oocytes 

 develop at approximately the same rate 

 upon reaching 400 idm. This uniform 

 development made oocytes that were 

 to be spawned easier to count. When 

 fecundity counts were used in conjunc- 

 tion with histological examination, 

 oocyte diameter measurements, and 

 gonadosomatic index, a more complete 

 measure of reproductive potential and 

 the timing of the spawning season was 

 possible. In addition, it was determined 

 that striped mullet that recruit into 

 South Carolina estuaries spawn from 

 October through April. 



Fecundity and spawning season of striped mullet 

 {Mugil cephalus L.) in South Carolina estuaries* 



Christopher J. McDonough 



William A. Roumillat 



Charles A. Wenner 



Marine Resources Research Institute 



South Carolina Department of Natural Resources 



217 Fort Johnson Road 



Charleston, South Carolina 29422-2559 



E-mail address (for C J McDonougfi): mcdonoughc@mrd.dnrstate.sc,us 



Manuscript approved for publication 

 19 June 2003 by Scientific Editor 



Manuscript received 26 June 2003 at 

 NMFS Scientific Publications Office. 



Fish Bull. 101:822-834 



The striped mullet iMugil cephalus L.) 

 is distributed circumglobally in tropi- 

 cal and semitropical waters between 

 latitudes 42°N and 42°S (Thompson, 

 1963; Rossi et al., 1998). Even though 

 considered a marine species, striped 

 mullet are euryhaline and can be found 

 year round throughout the full range of 

 estuarine salinities in the southeastern 

 United States (Jacot, 1920; Anderson, 

 1958). Striped mullet are a commer- 

 cially important fish throughout the 

 world sustaining both fisheries and 

 aquaculture industries. In the south- 

 eastern United States (North Carolina 

 and Florida) there are significant com- 

 mercial fisheries for striped mullet, 

 whereas in South Carolina and Georgia 

 landings are more limited (NMFS'). 



The primary fishery in most of these 

 states is for "roe" mullet during the 

 fall spawning migration. Throughout 

 the rest of the year mullet are fished 

 commercially for bait, if they are fished 

 at all (Anderson, 1958). Striped mullet 

 have a significant economic impact in 

 the areas where they are more heavily 

 fished by the commercial fisheries and 

 the landings of this species from 1994 

 to 1998 yielded a landings (wholesale) 

 value of 38.2 million dollars. Striped 

 mullet are also one of the most impor- 

 tant forage fishes that are found in the 

 estuaries of the southeastern United 

 States and represent a significant 

 food source for upper-level piscivores 

 (Wenner et al.^). 



The biological features of striped 

 mullet has been well documented 

 (Jacot, 1920; Anderson, 1958; Thomson, 

 1963, 1966; Chubb et al., 1981), but 



much less information is available on 

 the biological aspects of reproduction 

 in the wild (Anderson, 1958; Stenger, 

 1959; Greeley et al., 1987; Render et al, 

 1995). There is a large body of work con- 

 cerning striped mullet reproduction in 

 aquaculture but many of these studies 

 have used artificial manipulation of the 

 reproductive cycle. Although the matu- 

 ration process of oocytes may have been 

 the same as that in wild striped mullet, 

 the environment and conditions under 

 which maturation occurs were artifi- 

 cial (Shehadeh et al., 1973a; Kuo et al., 

 1974; Pien and Liao, 1975, Kelly, 1990; 

 Tamaru et al., 1994; Kuo, 1995). In ad- 

 dtion, despite the demonstrated ability 

 to initiate reproduction (both in and 

 out of season) for striped mullet, the 

 majority of aquaculture studies have 

 had to rely on wild fish for broodstock 

 (Kuo et al., 1974; Pien and Liao, 1975; 

 Kuo, 1995). 



* Contribution 522 of the Marine Resources 

 Institute, South Carolina Dept. of Natural 

 Resources, Charleston, SC 29422-2559. 



' National Marine Fisheries Service. 2001. 

 Personal commun. Statistics and Eco- 

 nomic Division, 1315 East-West Highway, 

 Silver Spring, Md. 20910. http://www. 

 St. nmfs.gov/stl/index. html. 



2 Wenner, C. A., W. A. Roumillat, J. E. Moran, 

 M. B. Maddox, L. B. Daniel, and J. W. 

 Smith. 1990. Investigations on the life 

 history and population dynamics of ma- 

 rine recreational fishes in South Carolina, 

 part 1. Completion report, project F-37, 

 p. 3-13 and project F-31, p. 6-35. South 

 Carolina Marine Resources Research 

 Institute, P.O. Box 12559, Charleston, SC 

 29422 



