OLLA and SAMET: COURTSHIP AND SPAWNING BEHAVIOR OF TAUTOG 



mained unchanged, with the trunk being a dark 

 gray. Occasionally in Study 2, we noticed tran- 

 sient shading changes on the dominant male that 

 were most apparent during aggression or court- 

 ship. In these cases the length of the male's mid- 

 section became a much lighter gray than the 

 darker, dorsal area of its body. This was not a 

 persistent change and lasted perhaps 1 or 2 min. 



Development of Pair Formation 



On 4 April 1975 in Study 1 (approximately 2 wk 

 prior to the first spawning), it was apparent that 

 there was in progress a transition from nonsexual 

 to sexual (courtship) activities between the dom- 

 inant male and female. We interpreted this to be 

 the development of pair formation, at least within 

 the context of the social situation and the un- 

 natural laboratory condition. 



In this same 2-wk period prior to the first spawn- 

 ing, the dominant's aggression directed at the 

 subordinate male not only persisted but also 

 began to increase and apparently served to inhibit 

 (suppress) the subordinate's motivation to either 

 court the female (i.e., by rushing her) and/or par- 

 ticipate eventually in any of the spawning ac- 

 tivities as long as the dominant was present. Since 

 our observations in Study 1 began after courtship 

 was under way, we were unable to ascertain the 

 initial responses of the subordinate male toward 

 the female, e.g., whether or not this male had 

 originally shown any receptivity to the female (or 

 vice versa) or attempted to court her. 



In contrast to Study 1, the development of pair 

 formation between the dominant male and female 

 in Study 2 was slightly altered at first by the 

 participation of the subordinate male. The domi- 

 nant male had initiated rushes at the female as 

 early as 29 January 1976 (7 wk prior to the first 

 spawning), but then on 23 February 1976, the 

 subordinate began to rush her periodically. In the 

 4-wk observation period (23 February- 18 March 

 1976) immediately prior to the first spawning, the 

 rushes by the dominant continued, averaging 

 8.8/day (range of 3-22/day), and while the rushes 

 by the subordinate also occurred, they were lower 

 in frequency, averaging 1.4/day (range of 0-5/ 

 day). 



The events during the first and subsequent 

 spawnings of Study 2 offered some preliminary 

 evidence that, while gamete release was not con- 

 tingent upon an established pair formation, this 

 type of social interaction ultimately prevailed, at 



least under laboratory conditions. On the date of 

 the first spawning, 19 March 1976, the female 

 mated not with the dominant, but with the subor- 

 dinate male. Although the dominant initiated 

 some of the final courtship behavior that normally 

 led to gamete release (see results below), and up to 

 a point, had continued to attack the subordinate, 

 eventually the dominant withdrew from all ac- 

 tivities, remained inside the shelter, and did not 

 interfere as the subordinate briefly rushed and 

 then released gametes with the female (details 

 described below). This type of pattern in which the 

 dominant initiated prespawning behavior, but 

 then withdrew and "allowed" the subordinate 

 final access to the female for spawning persisted 

 for 4 days through 22 March 1976. 



On 23 March the dominant began taking a more 

 active and sustained role in the final reproductive 

 behavior. Because of this and the fact that his 

 aggression towards the subordinate had been in- 

 creasing, it appeared that the dominant might be 

 the sole mate of the female. However, just as the 

 dominant and female were about to spawn, the 

 subordinate male rapidly approached the pair and 

 simultaneously released his gametes with theirs. 

 This pattern in which the dominant initiated and 

 completed the spawning activities with the 

 female, but still had not sufficiently inhibited a 

 simultaneous spawning release by the subordi- 

 nate male persisted for 7 days through 29 March 

 1976. 



It was not until 30 March, 11 days after the first 

 gamete release, that the spawning was completed 

 exclusively by the dominant male and the female. 

 Throughout the remainder of the study, the 

 female mated exclusively with the dominant 

 male. 



Daily Reproductive Behavior 



All spawnings that were observed during both 

 Studies 1 and 2 occurred between 1330 and 1600 

 (EST) with the exception of one at 1015 (EST) in 

 Study 1. The first spawning of Study 1 was on 21 

 April with 36 subsequent spawnings observed 

 (1-3/day), and in Study 2 the first spawning oc- 

 curred on 19 March 1976 with 22 subsequent 

 spawnings (1-2/day). 



Throughout the morning of a typical day when 

 spawning was to occur, the dominant male was 

 generally active, swimming about the tank, feed- 

 ing, and intermittently rushing the female. Ag- 

 gression towards the subordinate male usually oc- 



591 



