Sex Ratio 



A significant trend in the predominance of males occurred in Area 3 throughout 

 the study. Males comprised 75 percent of the population during study period 1, 

 69 percent in 2, 65 percent in 3, and 54 percent in 4. To avoid bias generated 

 by repeated resightings of a few individuals, each tagged lobster resighted 

 during a given study period was counted just once, either as newly tagged or 

 resighted (i.e., tagged during a prior period). Untagged lobsters were 

 excluded since individuals could not be identified during successive resight- 

 ings. The less intensively collected data from Areas 1, 2, and 4 support, in 

 general, this trend in sex ratio. 



The increase in relative abundance of females indicates that as the population 

 turnover progressed throughout the study, males were selectively moving out of 

 the study area and females were moving in. If a moderate decrease in popula- 

 tion size occurred, as may be indicated, then the selective emigration of males 

 exceeded the immigration of females. It is not known whether this phenomenon 

 is a naturally occurring event or whether it was related to a relatively high 

 level of harassment by divers working from the TEKTITE habitat. Sex ratio data 

 collected during the remainder of this 1-year study will help to determine the 

 cause of this trend. 



Habitation Patterns 



The live reef and hard-bottom regions within the study areas have literally 

 thousands of interstices and crevices in which at least one lobster could with- 

 draw. Yet the initial surveys showed that the 99 lobsters present (all areas) 

 occupied only 26 dens, an average of 3.8 lobsters per den. The frequency pro- 

 file suggests that multiple habitation was as frequent as individual habitation 

 even though many more small, single-lobster crevices were available (Table 7). 

 Multiples were particularly characteristic in Area 3 (worked by the aquanauts 

 at depths greater than 8 meters) in which an observed total of 46 lobsters 

 initially occupied only 7 dens (6.6 lobsters per den), the same dens frequented 

 by lobsters during TEKTITE I, March-April 1969. 



Table 7. Frequency of habitation of lobster dens 



No. lobsters 

 per occupied 



den = 1 2 3 4 5 6 7 8 9 10 >10 MEAN 



AREA-3 (APR) 2 2 2 10 1 



(MAY) 25 11 7 4 2 



(JUN) 17 14 1 1 2 1 



(AUG) 16 8 5 



(SEPT) 66 14 4 1 



1(18) 5.3 (Initial, 3 survey days) 

 1.9 (11 survey days) 

 1.9 (7 survey days) 

 1.6 ( 6 survey days) 

 1.3 (18 survey days) 



2.3 (Initial 2 survey days) 

 1.0 ( " " " " ) 

 3.0 ( ' " ) 



The most frequented dens in Area 3, below 8 meters, are concentrated in a con- 

 tiguous area of less than 6000 m out of a total habitable area (the area where 

 lobsters were observed in dens during the course of study) of approximately 

 45,000 m^ (Figure 1). Most of these dens (e.g., 3, 5, 14, 9, 10, 7) lie proximal 



VI-47 



