FISHERY BULLETIN: VOL. 75, NO. 3 



either the animals were not in complete reproduc- 

 tive synchrony or the confines of the aquarium 

 may have produced behavioral artifacts. 



In our studies, pair spawning, with the domi- 

 nant male tautog being the exclusive partner of 

 the female, was the prevalent mode of reproduc- 

 tive activity. However, in Study 2 when spawning 

 began, the female spawned first with the subordi- 

 nate male, then both males, and finally only with 

 the dominant. This transition period, we surmise, 

 may have been caused by either or both of the 

 following: 1) due to the small difference in size 

 (1.3 cm) between the males, dominance may not 

 have been sufficiently defined initially to inhibit 

 the subordinate, and 2) the final phase of seasonal 

 reproductive readiness of the dominant was 

 slightly behind that of the subordinate. Once the 

 dominant reached an appropriate level of sexual 

 maturation, pair spawning involving only the 

 dominant male and the female occurred exclu- 

 sively for the remainder of the study. 



Pair spawning again proved to be the mode of 

 gamete release in our laboratory facility when a 

 single male was in the presence of two gravid 

 females (Olla and Samet unpubl. data). In July 

 1976 these two females (approximately 48 and 58 

 cm) were introduced into the aquarium where the 

 dominant male from Study 2 was still residing. 

 During intermittent observations of the fish, pair 

 spawning occurred five times with the smaller 

 female, although both females were rushed and 

 exhibited a high degree of attention towards the 

 male. 



While we have never seen tautog spawning 

 under natural conditions, it is reasonable to as- 

 sume from our observations that pair spawning 

 may play a leading role in the reproductive reper- 

 toire of this species. However, we reserve judg- 

 ment as to whether this is the only pattern of 

 gamete release, especially because of the occur- 

 rence in Labridae of both paired and aggregate 

 spawnings within a single species, e.g., Thalas- 

 soma bifasciatum (Randall and Randall 1963) and 

 T. lunare (Robertson and Choat 1974), both of 

 which are protogynous hermaphrodites (Reinboth 

 1967 and Choat 1969, respectively). 



Another factor contributing to our reserve in 

 assigning only one pattern of reproduction to 

 tautog is that during recent preliminary field 

 studies, Olla and Bejda (in prep.) found sexually 

 mature young tautog, both males and females, 

 which were of a much smaller size and younger 

 age than has previously been reported 



596 



(Chenoweth 1963; Cooper 1966; Briggs in press). 

 In addition, these young fish did not show sexual 

 dimorphism of the mandible (Cooper 1967), a 

 characteristic trait which was conspicuous in the 

 subjects used in our studies. One explanation for 

 the absence of the mandibular dimorphism in 

 these young fish might be that this trait occurs in 

 older, larger fish. Although we do now know yet 

 whether the young animals participate in spawn- 

 ing, the other possibility is that these fish may 

 represent a different sexual stage than that of the 

 older fish of our study. It is even possible, as re- 

 mote as it seems, that hermaphroditism may be 

 present. The question is raised here because we 

 know nothing of the behavior or gonadal develop- 

 ment of these young fish and because hermaphro- 

 ditism, in the form of protogeny, has been found in 

 a number of labrids (e.g., 30 species according to 

 Robertson and Choat 1974). 



While it appeared that pair formation did take 

 place within the laboratory, whether or not a true 

 pair bonding between mates occurs in nature is 

 still unanswered. It is possible that in their 

 natural environment, other male tautog in the 

 vicinity of a pair could conceivably participate at 

 the moment of spawning. However, in these cir- 

 cumstances it is also quite possible that the ex- 

 treme aggression of a dominant, courting male 

 would cause other subordinate males to remain 

 sexually passive or to move away and seek a 

 female partner elsewhere. The hypothesis that 

 within a given locale a dominance hierarchy 

 among males determines which male becomes 

 sexually active is supported by a field experiment 

 on Thalassoma bifasciatum by Reinboth (1973). 

 Additionally, it is quite possible in a natural envi- 

 ronment that a female might spawn each day with 

 a different male. 



On the other hand, if true pair formation solely 

 between one male and a female is possible, the 

 selective advantage here is obvious, inasmuch as 

 1) it would not be necessary for an animal to ex- 

 pend energy finding a mate each day, and 2) to 

 sustain its dominance (and pairing with a female) 

 the male must continue to be a highly successful 

 competitor. When the motivation to spawn wanes, 

 males capable of becoming sufficiently dominant 

 over others would have priority to act as mates. 



Of all the sensory stimuli that could potentially 

 come into play during tautog courtship, visual 

 cues arising from the female appeared to be the 

 most conspicuous. First, the swollen, gravid ab- 

 domen of the female, which as Youngbluth (1968) 



