474 



Fishery Bulletin 102(3) 



Peterson, 2003; Wenner et al. 4 ). As in other indetermi- 

 nate spawning fish, annual fecundity in this species is 

 determined by the number of oocytes released during 

 each spawning event (batch fecundity) and the number 

 of spawning events occurring during the course of the 

 spawning season (spawning frequency!. Early efforts to 

 estimate fecundity for spotted seatrout did not take into 

 account the repetitive nature of spawning activities in 

 this species (Pearson, 1929; Sundararaj and Suttkus, 

 1962; Overstreet, 1983) and only recently has an effort 

 been made to coordinate batch fecundities with spawn- 

 ing frequencies (Brown-Peterson et al., 1988; Brown- 

 Peterson and Warren, 2001; Nieland et al., 2002). This 

 procedure is intuitively necessary to estimate the re- 

 productive output for an entire spawning season and 

 is made even more useful for fisheries management if 

 separated by size class or age cohort within a popula- 

 tion (Prager et al.. 1987; Goodyear, 1993; Zhao and 

 Wenner 5 ). 



An important component of assessment for manage- 

 ment involves determining the spawning potential ratio 

 (SPR), a measure of the effect of fishing on the repro- 

 ductive potential of a stock (Goodyear, 1993). This value 

 is usually calculated as the ratio of spawning stock 

 biomass per recruit (SSBR) in the presence of fishing 

 mortality (F) to the SSBR when F is equal to zero (Ga- 

 briel et al., 1989; Goodyear, 1993). Spawning potential 

 ratio is currently used as a biological reference point 

 for definition of recruitment overfishing (i.e., Vaughan 

 et al., 1992). The calculation of SPR can be improved, 

 however, by introducing egg production into the model. 

 Fecundity is a much better predictor of reproductive po- 

 tential than female biomass. Moreover, SPR calculations 

 based on egg production may be more sensitive to the 

 size-age composition of the spawning stock. However, 

 accurate annual fecundity estimates for use in stock 

 assessment do not exist for this or many other species 

 in need of fisheries management. Therefore, our goal 

 was to obtain batch fecundity (BF), spawning frequency 

 (SF), and annual fecundity (AF) estimates for spotted 

 seatrout by age class. 



Materials and methods 



Data to address the main objectives of this study were 

 collected from late April through early September 1998- 



1 Wenner, C. A., W. A. Roumillat. J. E. Moran Jr., M. B. Maddox, 

 L. B. Daniel III, and J. W. Smith. 1990. Investigations 

 on the life history and population dynamics of marine rec- 

 reational lishes in South Carolina: part 1. Final Report 

 F-37, 177 p. Marine Resources Research Institute, Marine 

 Resources Division, South Carolina Department of Natural 

 Resources, 217 Ft. Johnson Rd., Charleston, SC 29412 



s Zhao, B., and C. A. Wenner. 1995. Stock assessment and 

 fishery management of the spotted seatrout, Cynoscion nebu- 

 losus, on the South Carolina coast, 90 p. Marine Resources 

 K' i arch Institute, Marine Resources Division, South Caro- 

 lina Department of Natural Resources, 217 Ft. Johnson Rd.. 

 Charleston, SC 29412. 



2000 as part of a long term monitoring effort 11991-pres- 

 ent) to assess the relative abundance of age classes of 

 recreationally important finfish in South Carolina estu- 

 aries. The study followed a monthly stratified random 

 sampling design in three estuarine systems. The Cape 

 Romain system comprised two strata; Romain Harbor 

 and northern Bulls Bay. The Charleston Harbor system 

 contained four strata: the Wando, Cooper, and Ashley 

 Rivers, and Charleston Harbor. The Ashepoo-Combahee- 

 Edisto (ACE) Basin system comprised a single stratum 

 (Fig. 1). The number of sampling sites within each stra- 

 tum ranged from 23 to 30. A subset of 12-14 sites was 

 randomly selected each month. Sampling was conducted 

 only during the daytime ebbing tide (0700-1800 h), 

 primarily over mud and oyster shell substrates adjacent 

 to the Spartina alterniflora marsh. At each site, we 

 deployed a trammel net (182.8 m long by 2.4 m deep; 

 outer walls: 17.8 cm square (35.6 cm stretch]; inner wall: 

 3.2 cm square [6.4 cm stretch]) from a rapidly moving 

 shallow water boat in an arc against the shoreline at 

 depths ranging from 0.5 to 2.0 m. We disturbed the 

 water within the site in an effort to frighten fishes into 

 the entrapment gear. We then hauled the trammel net 

 back into the boat and removed the catch, which was 

 kept alive in a 70-liter oxygenated holding tank. Spot- 

 ted seatrout were measured for total length (TL) and 

 standard length (SL) and a subsample offish from each 

 effort (5-10 individuals for each 20-mm size interval per 

 month) were sacrificed, placed on ice, and transported to 

 the laboratory for aging and reproductive data. 



Specimens were processed in the laboratory 2-12 

 hours after capture. We recorded standard life-history 

 parameters (TL, SL, fish weight, gonad weight, sex, and 

 maturity) for each specimen. The following equation was 

 used to convert lengths when necessary: 



TL = 5.689 + 1.167ISL) (r- = 0.998) 



n = 1191. 



We removed sagittal otoliths for aging and preserved 

 sections (<2% by weight) of each ovary in neutral buff- 

 ered formalin for histological processing. The latter 

 involved standard procedures for paraffin embedding 

 and sectioning, and standard hematoxylin and eosin-y 

 staining (Humason, 1972). Histological sections were 

 viewed under a Nikon Labophot compound microscope 

 equipped with a teaching head so that two readers 

 could interpret sections simultaneously. Maturity 

 estimation was modified from that of Wenner et al. 4 

 (Table 1). 



Size at first maturity was histologically derived by 

 first evidence of cortical alveoli stage oocytes. To ar- 

 rive at estimates of 50% and 100% maturity, data were 

 subjected to PROBIT analysis. 



Age determination 



The left sagittae were marked with a soft lead pencil 

 through the core and embedded in epoxide resin. A 

 transverse section (~0.5-mm thick) was taken through 

 the core by using a low-speed saw equipped with a pair 



