White et al : Reproductive seasonality, fecundity, and spawning frequency of Tautoga onitis 



425 



and 31 years in Virginia (White, 1996). Growth parameters 

 offish between northern and southern regions (Hostetter 

 and Munroe, 1993) are comparable, except that Virginia 

 tautog have exhibited almost twice the growth increments 

 in young-of-the-year and age 13+ fish. Likewise, growth 

 relationships are similar for tautog from New York (Briggs, 

 1977) and Virginia (Hostetter and Munroe, 1993). 



Within preferred habitats, juvenile and adult tautog 

 develop home sites (011a et al., 1979). Tagging studies in- 

 dicate seasonal movements between inshore and offshore 

 habitats, but minimal north-south movement (Cooper, 

 1966; Briggs, 1977; Lynch-; Bain and Lucy''). During win- 

 ter, adult tautog located offshore of Virginia are active at 

 temperatures above 6.1°C (Adams, 1993). Likewise, tautog 

 at inshore locations within Chesapeake Bay (Arendt et al., 

 2001a, 2001b) remain active at water temperatures of 5°C 

 or above. In northern parts of its range, adult tautog move 

 inshore and spawn when water temperatures increase in 

 the springtime (Chenoweth, 1963; Cooper, 1966; Stolgitis, 

 1970; 011a et al, 1974, 1979), although some portion of the 

 population remains offshore year-round (011a and Samet, 

 1977; Hostetter and Munroe, 1993). Very little is known 

 about the reproductive biology of tautog in Virginia. Tau- 

 tog begin spawning when water temperatures reach about 

 11°C (Chenoweth, 1963; 011a et al., 1974, 1980; Eklund 

 and Targett, 1990; Hostetter and Munroe, 1993); thus the 

 spawning season begins later in the spring at higher lati- 

 tudes. Spawning season extends from mid-April through 

 June in Virginia (Hostetter and Munroe, 1993), mid-May 

 through early August in Massachusetts (Stolgitis, 1970), 

 and from late May to early June in Rhode Island (Che- 

 noweth, 1963). Macroscopic gonad analyses and gonadoso- 

 matic indices have indicated that male tautog mature by 

 age 3 and females by age 3-4 throughout the species range 

 (Chenoweth, 1963; Cooper, 1967; Stolgitis, 1970; Briggs, 

 1977; Hostetter and Munroe, 1993); however, sample sizes 

 of young (age 2-3) fish were small in these studies, and 

 earlier maturation has been noted (011a and Samet, 1977; 

 Hostetter and Munroe, 1993). To date there has been no 

 histological examination of the reproductive biology of this 

 species in Virginia, or elsewhere. 



In laboratory aquaria, tautog have been observed to be 

 a multiple spawning species, spawning as discrete pairs 

 and as groups (011a and Samet, 1977; OUa et al., 1977). 

 Although hermaphroditism is common among labrids 

 (Warner and Robertson, 1978), tautog are thought to be 

 strictly gonochoristic (Olla and Samet, 1977). However, 

 two color patterns of males exist in samples from Virginia 

 waters; approximately 85% of males exhibit strong dimor- 



^ Lynch, T. R. 1996. Marine finfish investigation, sport fish 

 population survey in Rhode Island marine waters: tautog stud- 

 ies, 1987-1993. " Rhode Island Division of Fish and Wildlife 

 performance report project: F-54-R-1, study I-I. reference docu- 

 ment TT-396, 55 p. Rhode Island Division of Fish and Wildlife, 

 Marine Fisheries Section, 3 Fort Wetherill Road, Jamestown, RI 

 02835. 



^ Bain.C. M.and J. A. Lucy. 1996. Virginia Game Fish Tagging 

 Program annual report, 1995. Virginia Mar Res. Rep. 96-2, 10 p. 

 Virginia Marine Resources Commission, 2600 Washington Ave, 

 Newport News, VA 23067. 



phism and 15% of smaller males (<550 mm) show external 

 coloration similar to females (Hostetter and Monroe, 1993, 

 this study). Further, histological analysis of 379 male tau- 

 tog revealed no evidence of hermaphroditism (Munroe and 

 White, unpubl. data) 



The reproductive potential of tautog, measured as annu- 

 al fecundity, has not been addressed to date. To accurately 

 estimate potential annual fecundity for multiple spawning 

 species, batch fecundity must be multiplied by the number 

 of spawnings per year, i.e. spawning frequency multiplied 

 by spawning season length (Hunter and Macewicz, 1985). 

 Chenoweth (1963) and Stolgitis (1970) estimated batch 

 fecundity and length of spawning season but did not mea- 

 sure spawning frequency. The only estimate of number of 

 spawnings per female per year were those of Olla et al. 

 (1977), who observed tautog spawning daily for 68-96 

 consecutive days in laboratory aquaria; however, results 

 obtained in aquaria studies may not directly apply to natu- 

 ral habitats and have not been used to estimate potential 

 annual fecundity. 



Our study, the first to investigate cellular aspects of 

 the reproductive biology of tautog in natural habitats of 

 the lower Chesapeake Bay, was necessary 1) to describe 

 this species as a determinate or indeterminate spawner; 

 2) to describe annual and spawning season ovarian cycles 

 at the cellular level; 3) to assess age at maturity based on 

 histological sections of gonad tissue; 4) to estimate batch 

 fecundity for females from the southern portion of the spe- 

 cies range; 5) to estimate spawning frequency; and 6) to 

 estimate potential annual fecundity. 



Materials and methods 



A total of 960 tautog (>150 mm total length [TL]) were 

 collected opportunistically between April 1994 and Sep- 

 tember 1995 from commercial and recreational fishermen 

 (ca. 909c ) as well as from research projects (ca. 10% ) at Vir- 

 ginia Institute of Marine Science (VIMS). A minimum size 

 of 150 mm TL was selected based on maturity information 

 presented in Hostetter and Munroe ( 1993). Collection loca- 

 tions ranged from Gwynn's Island at the mouth of the Rap- 

 pahannock River to 45 km offshore of Virginia's coastline, 

 at depths of 1-35 m (Fig. 1). Approximately one quarter of 

 the fish were taken from within the Chesapeake Bay, one 

 quarter from the Chesapeake Bay Bridge Tunnel (CBBT, 

 depth=5-15 m), and one half from around the Chesapeake 

 Bay Light Tower (24 km offshore, depth= 17-20 m). 



For each fish, total length (mm) and total weight (TW. g) 

 were measured. Sex was assessed externally from sev- 

 eral dimorphic characters previously described by Cooper 

 (1967), Olla and Samet (1977), and Hostetter and Munroe 

 (1993). Males were distinguished by their pronounced 

 white chin, blunt forehead, solid black or gray coloration 

 on the upper half of the body and white underneath, and 

 a small white spot (about 15 mm diameter) mid-laterally, 

 below the middle of the dorsal fin. Female tautog have a 

 less pronounced chin, sloped forehead, and a mottled brown 

 coloration. After determination of sex (external examina- 

 tion), gonads were excised, staged macroscopically, and 



