Sogard et al : Early life history of Tautoga onitis in the Mid-Atlantic Bight 



537 



Sogard 1991, Szedlmayer and Able In press), and we 

 caution that this may also be the case for tautog 

 otoliths. 



Settlement 



Increment coimts preceding the settlement mark aver- 

 aged 20.4, suggesting larvae spend approximately 3 

 weeks in the plankton before settling to the benthos. 

 This estimate of larval stage duration is similar to that 

 derived by Victor (1986) for a sample of five tautog 

 (x 25.4). The planktonic stage for tautog is relatively 

 short compared with other labrids; Victor (1986) esti- 

 mated average larval durations of 17-104 days for 

 other wrasse species. 



The earliest estimated date of settlement, based on 

 otolith increments, was earlier than the first collections 

 of juveniles with throw traps, suggesting that tautog 

 were not available to the collecting gear during and im- 

 mediately after settlement. The smallest juveniles for 

 which we have otolith information were 7. 6-13. 2mm 

 SL and had 11-28 increments (i 16.3) deposited after 

 the settlement mark. Victor (1983) reported that new- 

 ly settled wrasses of the species Halichoeres bivitta- 

 tus bury in sediments immediately following settlement 

 from the plankton and remain buried for an average 

 of 5 days. We do not know if a similar behavior occurs 

 in Tautoga onitis. 



Juvenile habitat utilization 



Our collection of juvenile tautog primarily in vegeta- 

 tion is in accord with prior studies, which demonstrated 

 an association with structured habitats (011a et al. 1974, 

 011a et al. 1979). Several studies comparing eelgrass 

 vs. unvegetated substrates noted significantly higher 

 densities of tautog in grassbeds, with few or no tautogs 

 collected on bare substrates (Briggs and O'Connor 

 1971, Orth and Heck 1980, Weinstein and Brooks 1983, 

 Heck et al. 1989). The importance of sea lettuce as a 

 nursery habitat has received only limited attention, 

 although Nichols and Breder (1926) mentioned its at- 

 traction to small juvenile tautog. In a separate study 

 that also quantitatively compared sea lettuce and 

 eelgrass habitats in New Jersey, using suction sam- 

 pling. Able et al. (1989) also noted higher abundances 

 of early juvenile tautog in sea lettuce patches than in 

 eelgrass, although the total catch was relatively small. 

 Larger juveniles make extensive use of rocky reef 

 habitats (011a et al. 1979). The importance of hard 

 substrates for newly settled tautog has not been 

 examined. 



All of the smaller juvenile tautog (<35mmSL) that 

 we collected were from sea lettuce patches or artificial 

 seagrass plots. These individuals were a brilliant green 



in color. As noted by Nichols and Breder (1926), this 

 color closely matches that of Ulva lactuca, but pre- 

 sumably would be conspicuous on a bare sand sub- 

 strate. In our sampling, these early juveniles were ab- 

 sent from eelgrass beds. The larger juveniles collected 

 during trawl sampling (in eelgrass and other habitats) 

 had a dark, mottled coloration similar to that of the 

 adults as depicted by Bigelow and Schroeder (1953). 



Over the course of our summer sampling, we ob- 

 served a shift in concentration of young-of-the-year 

 from the shallow areas sampled by throw traps to 

 deeper waters sampled by otter trawl (Fig. 6). This 

 shift suggests that newly-settled juveniles concentrate 

 in shallow waters, moving to deeper sections of the 

 estuary with growth. 



Although trawling was conducted year round, in- 

 dividuals of age 1 or older were common only from June 

 through September. This pattern could result from in- 

 accessibility to the gear. Some individuals may move 

 out of shallow habitats in the fall to deeper areas of 

 the estuary with more stable sheltering refuges. 

 Behavioral responses displayed by tautog in cold 

 temperatures, i.e., dormancy and remaining in close 

 contact with sheltering structure (011a et al. 1974) or 

 burying in sediments (011a et al. 1979), would also 

 reduce capture rates in winter. In addition, some in- 

 dividuals may leave the estuary to winter offshore, 

 although 011a et al. (1974) suggest that most tautogs 

 less than 4 years old remain inshore. 



Tautogs older than 1 year may be more abundant in 

 the estuary than trawl catches would indicate. Larger 

 individuals inhabit holes and crevices of eroding salt 

 marsh banks, and other physical structures such as 

 pilings and rock jetties, where they would not be 

 available to trawling gear. 



Juvenile growth 



Our estimates of sizes attained by juvenile tautog at 

 the end of the first and second summers are larger than 

 the mean lengths (TL) at ages 1 and 2 calculated for 

 Rhode Island tautog from opercular bone annuli 

 (Cooper 1967). Warmer temperatures in New Jersey 

 may support faster mean growth rates than in Rhode 

 Island. In addition, more southern estuaries in the 

 tautog's range have an extended summer season, 

 allowing both earlier spawning in the spring and con- 

 tinued rapid growth prior to declining water temper- 

 atures in the fall. 



Analysis of length progressions and otolith ages 

 resulted in two similar estimates of natural growth 

 rates for juvenile tautog (0.52 mm/day and 0.47mm/ 

 day). Individual growth rates of juvenile tautog were 

 also measured in the field in caging experiments 

 (Sogard In press). To summarize results of Sogard 



