OLLA and SAMET: COURTSHIP AND SPAWNING BKHAVIOR OF TAUTOG 



rather passive role in stimulating the dominant 

 male's attention (except when she simultaneously 

 entered the shelter with him), the female of Study 

 2 was behaviorally much more conspicuous in at- 

 tracting the attention of both males, particularly 

 as they fed. On several occasions the female not 

 only ingested mussels from the same small pile on 

 which a male was feeding, but even wrested a 

 clump of mussels from a male's mouth. This be- 

 havior was readily tolerated by both males. 



In contrast to the termination of aggressive in- 

 teractions between the dominant male and the 

 female during this early prespawning period, the 

 aggression of the dominant towards the subordi- 

 nate male began to increase both in frequency and 

 in intensity. In Study 1, aggressive acts by the 

 dominant toward the subordinate rose from an 

 average of 2.4/h during the nonreproductive 

 period to 16.0/h in the week prior to the first 

 spawning. In Study 2 aggressive acts rose from an 

 average of 2.6/h during the nonreproductive 

 period to 6.3/h in the week prior to spawning. Once 

 daily spawning began in both studies, intermale 

 aggression remained consistently high and was 

 significantly greater during the entire reproduc- 

 tive period than during the nonreproductive 

 period (Ps=0.05; end count test; Tukey 1959; 

 Table 1). 



The heightened intensity of aggression was 

 reflected by the increased duration of a chase, 

 which commonly lasted as long as 60 to 90 s with 

 the two fish covering anywhere from 1 to 3 circuits 

 around the tank. In both Studies 1 and 2, the other 

 obvious factor reflecting this heightened aggres- 

 sion was that the dominant began nipping and 

 biting the subordinate during chases. As a result, 

 each subordinate male in Studies 1 and 2 bore 

 numerous wounds on all areas of its body. 



One further piece of evidence of the increased 

 aggression of the dominant male in each study was 

 that the subordinate male now spent the majority 

 of time confined to either end of the aquarium, 

 sculling in place along the wall between middepth 

 and the surface. These locations appeared to be the 

 ones which elicited least aggression by the domi- 

 nant male. 



Along with behavioral changes, external 

 changes in the appearance of the female were also 

 occurring with the onset of the reproductive 

 period. Enlargement of the gonads increased the 

 girth of the female, resulting in a more rotund 

 appearance. At the same time, we also noted 

 minor changes in the female's pigmentation. 



TABLE 1. — Comparison of aggressions by dominant male toward 

 subordinate male Tautoga onitis for 11 days during nonrepro- 

 ductive and reproductive (spawning) periods of Studies 1 and 2. 

 Data are presented as a mean of 8 h/day ( 0800-1500 EST) during 

 nonreproduction and reproduction. 



1 - = Values for aggression during nonreproduction smaller than smallest 

 reproduction value. 



2 + = Values for agression during reproduction greater than greatest non- 

 reproduction value. 



While prior to this period she was generally a solid 

 dark gray, now there was a mottled white, vertical 

 bar or stripe down the middle of each side of the 

 body, which we termed a "saddle." At this time, 

 the saddle was in an early stage of development 

 (Figure la) of what was to be a progression of 

 significant shading changes taking place prior to 

 and during each daily spawning (see below for 

 further explanation). In addition, a pale, 

 grayish-white patch developed in the inter- and 

 supraorbital areas of the female, giving the ap- 

 pearance of eyebrows. The first observations of the 

 female's saddle were made on 11 April 1975 in 

 Study 1 and 29 January 1976 in Study 2. 



Unlike the female, the dominant male's appear- 

 ance prior to and during spawning was altered 

 very little. The only discernible shading changes 

 of the dominant males of both studies were the 

 development of a light gray shading covering the 

 entire head and opercula, and the transient ap- 

 pearance of faint white rays (approximately 2-4 

 cm long) extending outwards from the orbits of the 

 eyes. Additionally, it appeared that the ventral 

 portion of the maxilla and the entire mandible 

 became a lighter, almost white, shade, with the 

 exception of the dark pores of the mandibular lat- 

 eral line canals. Otherwise the male's shading re- 



589 



