virtually all lobsters eventually emigrated out of the entire study area (1, 1, 

 3, 4) with some (about 12%) reappearing up to several months later (Figure 6). 

 Since unmarked lobsters continually appeared, the population was transient on a 

 time scale of several months or less (discussed above). The fact that of 184 

 lobsters tagged in all three study areas, only two were resighted in other than 

 the original study area, which suggests that emigrants move either offshore or 

 for distances exceeding one kilometer alongshore. They do not move by small 

 increments alongshore. The consistent appearance of untagged lobsters in the 

 main dens (3, 5, 14, 9, 7), and the reappearance there of tagged animals after 

 long periods of absence, suggests that many of the lobsters coming into the area 

 (perhaps 50%) are already familiar with the region. 



No striking seasonal pattern of movement or degree of immigration/emigration is 

 apparent. There were no indications of mass movements involving a large propor- 

 tion of the resident population or any large influx of immigrants. 



Diver Impact on Habitation/Movement Patterns 



At the end of mission 2-50 it was noted that the distribution of lobsters in 

 Area 3 had changed markedly since the first week. Intensive tagging and other 

 handling was hypothesized as a possible disruptive influence. Indeed, newly 

 tagged lobsters were significantly more prone to vacate a den by the next day 

 than lobsters marked previously and merely surveyed visually; e.g., 847o of the 

 newly tagged lobsters left the original den site by the next day as compared to 

 587o of the resighted lobsters. Changes in behavior noted, but not quantitatively 

 analyzed, were (1) immediate travel to another den, even by day, by some newly 

 tagged lobsters; (2) increase in wariness by tagged lobsters and a tendency to 

 readily retreat when approached by a diver; and (3) increasing avoidance to 

 snare capture by tagged lobsters caught frequently for sonic tagging. 



The most apparent change in the Area 3 population was dispersal out of the 

 originally frequented dens (such as 3, 5, 14, 9) into atypical, previously empty 

 crevices. Figure 9 shows the steady increase in number of dens established in 

 Area 3 from the original 7 in the early part of 2-50 to a total of 70 by the 

 end of 12-50. The original dens continued to be the most frequent sites of 

 first appearance of untagged lobsters. At the same time, the frequency of 

 habitation of these dens by marked lobsters decreased. This suggests active 

 avoidance of these dens by lobsters after capture there. The dispersal appeared 

 also as an initial decrease in the number of lobsters per occupied den, from 5.3 

 to 1.9, which, after the first two weeks of mission 2-50, remained relatively 

 constant (Figure 10). While the number per occupied den remained constant or 

 decreased slightly, the number of lobsters per den, considering all dens checked, 

 decreased steadily as more new dens were established. The frequency profiles of 

 occupancy for the periods late April - early May, late May - early June, and 

 late July - early August are similar and show that multiple occupancy continued 

 to be as frequent as individual occupancy. However, there were few dens with as 

 many as five individuals, whereas originally several dens had from 6-18 

 lobsters (Table 7) . 



VI-52 



