58 



Fishery Bulletin 91(1). 1993 



Growth and sexual strategy 



The present study, and previous ones conducted in more 

 northern waters (Chenoweth 1963, Cooper 1967, 

 Stolgitis 1970, Briggs 1977), found that male tautog 

 mature by age-3 and females by age-4. Similar age-at- 

 maturation for tautog from different portions of the 

 species range for the present population of tautog liv- 

 ing in Virginia's coastal waters, and that reported 

 by Cooper 25 years ago (1967) for tautog from 

 Narragansett Bay, may reflect demographics of popu- 

 lations that have not sustained intensive exploitation. 

 It would be valuable to compare age-growth data for 

 the present-day population of tautog residing in 

 Narragansett Bay with historical data in Cooper (1967) 

 to test this hypothesis. 



It is unknown what percentage of tautog in a popu- 

 lation mature precociously, under what environmental 

 or social situations, or even if smaller fish are sexually 

 active and reproduce successfully. In May 1985, the 

 second author collected a 180mmTL, age-2 gravid fe- 

 male north of the confluence of the Taunton River and 

 Mount Hope Bay, Massachusetts. In the present study, 

 no sexually mature females smaller than 230mmTL 

 or younger than age-3 were found. We note, though, 

 that our data are limited for age-2 fish, especially for 

 fish of this age-group during their second summer and 

 fall. Olla & Samet ( 1977) also reported collecting sexu- 

 ally mature tautog "which were of a much smaller size 

 and younger age [no sizes or ages reported] than has 

 previously been reported" from coastal waters of New 

 York and northern New Jersey. It is interesting to note 

 that precocious individuals have only recently been 

 reported, and these were tautog occurring in northern 

 waters where sport and localized commercial fisheries 

 have operated historically since the 1800s (Goode 1884) 

 and have undoubtedly intensified since that time. Ear- 

 lier maturation is a common compensatory response 

 in fish populations subjected to intensive exploitation 

 (Goodyear 1980) and may explain the appearance of 

 precocious individuals in tautog populations inhabit- 

 ing northern portions of the species range where ex- 

 ploitation has occurred for a longer time. 



Sex ratios for tautog divided into 10 cm length-groups 

 were found to deviate significantly from a 1:1 ratio in 

 the larger size-classes, with larger (and older) size- 

 classes of tautog being comprised predominantly of 

 males. Based on a smaller sample size, Eklund and 

 Targett ( 1990 ) also reported a sex ratio (0.86:1) skewed 

 in favor of males. Small sample size in their study, 

 however, precluded breakdown of sex ratios over the 

 size range studied. Among other factors, skewed sex 

 ratios in larger (and older) fish may be attributed to 

 differential growth and longevity of males or slowing 

 of growth (measured as TL) with age in females, or 



possibly as a result of sex reversals. Faster growth 

 coupled with greater longevity for male tautog found 

 in Virginia's coastal waters may reflect the higher en- 

 ergetic costs of reproduction and subsequent earlier 

 senescence and differential mortality for females, as 

 suggested by Cooper (1967). Larger size may also be 

 selected for in males. Observations of courtship and 

 spawning reveal that a size-related male dominance 

 hierarchy is one reproductive mode (group spawning 

 without a dominance hierarchy is the other) occurring 

 in tautog with dominant males exhibiting strong terri- 

 toriality and performing a protracted courtship with 

 females, culminating in pair-spawning (Olla & Samet 

 1977). In reproductive strategies involving pair-spawn- 

 ing, territoriality, and dominance social hierarchies, 

 size selection for large males would be advantageous. 

 Such strong size and sexual selection is known in other 

 labrids, including bluehead wrasse Thalassoma 

 bifasciatum (Warner et al. 1975), California sheeps- 

 head Semicossyphus pulcher (Warner 1975), cunner 

 Tautogolabrus adspersus (Johansen 1925, Pottle & 

 Green 1979a,b), and others (Warner & Robertson 1978), 

 where females primarily select larger (older) males as 

 spawning partners. 



Although diandric male phases are prevalent in both 

 tropical and temperate labrids (Robertson & Choat 

 1974, Warner & Robertson 1978, Dipper & Pullin 1979), 

 diandric male tautog were not reported in earlier stud- 

 ies (Chenoweth 1963, Cooper 1967). Olla & Samet 

 (1977), following Cooper (1967), noted in their study 

 on spawning behavior that "tautog were easily identi- 

 fiable with respect to their gender by the sexually di- 

 morphic mandible, which is more pronounced in males." 

 However, in that same paper, unpublished data of Olla 

 & Bejda noted the occurrence of sexually-mature young 

 tautog of both sexes, without any sexual dimorphism. 

 Olla & Samet (1977) suggested that mandibular di- 

 morphism in tautog may develop ontogenetically, be- 

 coming apparent only in older, larger fish. In contrast, 

 we found wide overlap (up to ~50cmTL) in body size 

 between the two male forms, rendering it unlikely that 

 age alone controls development of secondary male char- 

 acteristics in tautog. 



Olla & Samet (1977) also discussed the possibility 

 that younger, mature fish may represent a different 

 sexual stage than that of older fish. They pointed out 

 that nothing was known of behavior or gonadal devel- 

 opment of these young fish, and that it was even re- 

 motely possible that tautog might be hermaphroditic. 



Since two spawning strategies have been observed 

 in male tautog (Olla et al. 1977, 1981), it is possible 

 that diandric males are those that utilize different re- 

 productive strategies. Since non-dimorphic males have 

 coloration patterns reminiscent of females, they may 

 increase spawning opportunities through sneak or in- 



