reefs. Movement patterns reported 

 by Dawson and Idyll (1951) tend to 

 confirm that most released lobsters 

 move to the south, but many move to 

 the north as well. Smith (1958) 

 observes that lobsters tend to move 

 offshore during cooler months. 



Autumnal mass migrations of 

 spiny lobster have been noted to 

 occur in Florida waters, and have 

 been extensively studied elsewhere 

 in the Carribean (Herrnkind, 1969, 

 1975, Herrnkind et al. 1975, Kanci- 

 ruk and Herrnkind 1978). In this 

 peculiar behavior, which occurs sub- 

 sequent to the summer mating season, 

 lobsters are observed to slowly 

 congregate in a given area, possibly 

 cued to do so by changing photo- 

 period (Kanciruk and Herrnkind 1973, 

 1978). As they congregate, activity 

 levels increase and small queues 

 begin developing on a diurnal sched- 

 ule; queues refer to the lining up, 

 single file of 2 or more lobsters 

 ultimately leading to mass migration 

 of large numbers of individuals. 

 Nonmigratory lobsters may also 

 queue, but not nearly to the same 

 extent. 



Autumnal queuing behavior is 

 apparently unrelated to the repro- 

 ductive cycle of lobsters. Rather, 

 Kanciruk and Herrnkind (1978) cor- 

 relate the migratory crescendo of 

 lobsters with the first significant 

 temperature drop accompanying winter 

 frontal systems. Subsequent winter 

 storms, though they may be more 

 severe than the first, do not elicit 

 the same response. 



The function of the mass migra- 

 tion remains largely a mystery, 

 although Bill and Herrnkind (1976) 

 report that mass migration of lob- 

 sters reduces hydrodynamic drag per 

 individual. They calculate that a 

 queue of 20 lobsters experiences 

 only about half the drag that the 



same number of individuals experi- 

 ence moving on their own. It seems 

 certain that the combination of 

 movement by individuals and movement 

 by autumnal mass migrations serves 

 to keep the lobster population well 

 mixed, if nothing else. 



The long term effects of com- 

 mercial and sport harvest on the 

 spiny lobster population has long 

 been a question of considerable 

 interest. Dawson and Idyll (1951), 

 Sweat (1968), and Little (1972) 

 state that the results of tagging 

 studies suggest underharvesting of 

 the Keys stock. Frankly however, 

 there is little information in such 

 results upon which to base this 

 conclusion. Recently, Davis (1974, 

 1977), Warner et al. (1976) and 

 Lyons et al. (1981) have presented 

 interesting and definitive data on 

 the impact of harvesting on lobster 

 populations in the Florida Keys and 

 Dry Tortugas. 



In anticipation of opening a 

 portion of the Dry Tortugas National 

 Monument to sport lobstering, the 

 local lobster population was moni- 

 tored for 29 months (Davis 1977). 

 The study area was divided into 

 three areas, an outer commercial 

 harvesting area; an inner area, part 

 of which was designated to be open 

 to sport harvest; and the remainder 

 of which was to serve as an unhar- 

 vested control area. 



During the initial monitoring 

 period Davis established that there 

 was a healthy resident population of 

 spiny lobsters. This suggests that 

 Carribean import is relatively less 

 important than previously thought, 

 at least in the Dry Tortugas. Indi- 

 rect evidence for this assessment 

 comes from a comparison of size 

 class distribution differences 



between the commercially fished area 

 and the unharvested monument area. 



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