White el al.: Reproductive seasonality, fecundity, and spawning frequency of Tautoga onttis 



439 



found that males matured at 200 mm (age 3) and females 

 at 190 mm (age 3). 



For a small number of fish sampled in northern areas, 

 Hostetter and Munroe (1993) suggested that precocious 

 development may be occurring in tautog as a response to 

 fishing pressure. The smallest females collected in spawning 

 condition have been 227 mm in Virginia (this study), 261 

 mm in Massachusetts (Stolgitis, 1970), 216 mm (Chenoweth, 

 1963) and 180 mm (Hostetter and Munroe, 1993), in Rhode 

 Island. A definitive answer on precocious development is not 

 possible at this time because data on small fish are limited 

 in all studies. Detailed histological analysis should be per- 

 formed on tautog from 100 to 250 mm TL to discern maturity 

 schedules for specimens in this size range. 



Spawning season and location 



Tautog spawn over at least a two-month period throughout 

 the species range, and the initiation of spawning activity 

 occurs later in the spring to early summer in more north- 

 ern regions (Chenoweth, 1963; Stolgitis, 1970; Briggs, 

 1977; Hostetter and Munroe, 1993). In our study, spawn- 

 ing occurred from 7 April through 15 June 1995 (70 days), 

 similar to the time interval reported by Hostetter and 

 Munroe ( 1993) for tautog in Virginia. In New York waters, 

 tautog have been recorded to spawn for four months (early 

 May through early September; Austin, 1973). In Rhode 

 Island, tautog spawn from early June through late July 

 (Chenoweth, 1963), and spawning seasons as long as 

 three months (mid-May through early August) have been 

 reported for fish in Massachusetts (Stolgitis, 1970). Abun- 

 dance of tautog eggs in plankton collections also shows that 

 the spawning season occurs progressively later in more 

 northern regions (Sogard et al., 1992). The earlier spawn- 

 ing season in Virginia has been attributed to differences in 

 water temperature (Hostetter and Munroe, 1993). Increas- 

 ing water temperature during springtime is a major cue to 

 initiate spawning, but termination of spawning activity has 

 not been related to environmental cues. However, Austin 

 (1973) suggested that the effective spawning season may 

 be shorter than the season of egg release for this species, 

 based on a decrease in larval abundance as water tempera- 

 ture exceeded 21.0°C in Long Island Sound. 



Tautog were collected in spawning condition within the 

 Chesapeake Bay and as far as 56 km offshore in this study 

 and by Hostetter and Munroe (1993). Eklund and Targett 

 (1990) sampled tautog in spawning condition 22-37 km 

 off the coast of Maryland and Virginia. Field observations 

 of daily movements showed that tautog exhibit fidelity 

 to a home site which they return to each night (011a et 

 al., 1974, 1975), suggesting that tautog remain at one 

 location throughout the spawning season. Arendt et al. 

 (2001b) found that tautog tended to move between sites 

 during the winter and early spring as the spawning sea- 

 son began and remained at a single site throughout the 

 summer. Tagging studies indicate that discrete spawning 

 groups exist at sites in Narragansett Bay (Cooper, 1966); 

 however, movements between sites were not quantified. 

 Sufficient data are not available to determine if tautog ex- 

 hibit spawning-site fidelity throughout the spawning sea- 



son, or if multiple spawning sites are used within general 

 inshore and offshore classifications. It is generally believed 

 that most tautog migrate inshore in the spring to spawn 

 (Cooper, 1966) and some portion of the population remains 

 offshore year round (Eklund and Targett, 1990; Hostetter 

 and Munroe, 1993). Although we have documented adult 

 spawning activity at both inshore and offshore locations, 

 spawning success in these areas, as well as larval drift and 

 recruitment patterns, are unknown at this time. 



Spawning pattern and type of fecundity 



Histological analysis of ovarian tissue supports the clas- 

 sification of tautog as a multiple spawning species with 

 a complex reproductive cycle. The complexity of ovarian 

 maturation (Fig. 6) in this species has not been recognized 

 in previous studies on its reproductive biology. The typical 

 cycle of female development for multiple spawning species 

 is defined by eight microscopic gonad stages (Lowerre-Bar- 

 bieri et al., 1996) which include an annual cycle (5 stages) 

 and an inner spawning cycle (3 stages). Although tautog 

 have been observed to be multiple spawners in laboratory 

 aquaria (Olla and Samet, 1977; Olla et al, 1977), we define 

 oocyte development and type of fecundity using recently 

 improved methods (Lowerre-Barbieri and Barbieri, 1993) 

 and histological techniques on fish taken from natural envi- 

 ronments; therefore, they are directly comparable to other 

 studies of reproductive biology without artifacts associated 

 with aquarium conditions. Analysis of oocyte size-frequency 

 distributions and histological sections of ovarian tissue 

 indicates that tautog have asynchronous oocyte develop- 

 ment and indeterminate annual fecundity. Therefore, 

 counting the number of oocytes in the ovary prior to the 

 spawning season is inadequate to measure potential annual 

 fecundity because new batches of eggs continuously mature 

 from primary growth oocytes through hydrated oocytes and 

 are released during spawning events (Hunter et al., 1985). 

 Chenoweth ( 1963) analyzed oocyte size-frequency distribu- 

 tions of three tautog collected over the course of the spawn- 

 ing season in Rhode Island and noted that the number of 

 mature yolked oocytes did not decline through the spawn- 

 ing season. He suggested that not all yolked oocvtes were 

 spawned and that some portion remained in the ovary and 

 were resorbed after the spawning season. This observation 

 is consistent with asjoichronous oocyte development. 



Fecundity 



This is the first study on tautog reproduction for which 

 potential annual fecundity has been estimated by multiply- 

 ing batch fecundity by spawning frequency. Batch fecundity 

 was more closely related to total length and total weight 

 than to age. This result makes sense when one considers 

 the extreme variability in length at age exhibited by tautog 

 (Cooper, 1967; Hostetter and Munroe, 1993). Batch fecun- 

 dity ranged from 2800 eggs to 181,200 eggs in 29 females 

 age 3-9 (Fig. 7). The oldest tautogs collected in this study 

 were a 31-year-old male and a 17-year-old female. After 

 reaching maturity, individual females may spawn up to 58 

 times a year for at least 14 years. 



