Estrella and Morrissey: Seasonal movement of Homarus americanus 
475 
Rhode Island. They concluded that the lobsters 
tended to remain in shoal waters in suitable spawn- 
ing habitat until they had shed their eggs or had 
molted, or both. Cooper and Uzmann ( 1971) referred 
to seasonal movement to and from generalized ar- 
eas: the edge of the continental shelf and the shoaler 
waters of southern New England. Campbell (1986) 
and Pezzack and Duggan ( 1986), however, provided 
evidence from Canadian waters that lobsters under- 
take regular migrations between widely spaced and 
well-defined areas. 
In contrast, the European lobster, Homarus 
gammarus, although biologically similar to H. 
americanus, displays minimal migratory behavior 
(Bannister and Addison, 1995). Tagging studies have 
shown that both juveniles and adults exhibit “strong 
site loyalty.” The distribution of the H. gammarus 
resource and fishery is primarily coastal; “offshore” 
distribution occurs only 20 km from shore. The lack 
of substantial long-distance movement may be due 
to the more moderate water temperature off the Brit- 
ish Isles (compared with the NW Atlantic) caused by 
proximity to the Gulf Stream. This may mitigate the 
biological “need” for extensive seasonal inshore-off- 
shore movement by H. gammarus , 8 
There is an apparent affinity between the migra- 
tory group of lobsters east of Cape Cod, which are 
examined in this study, and those from Georges Bank 
and southern offshore canyons. Our evidence for 
movement of these lobsters north of Cape Cod into 
the Gulf of Maine seasonally, implies that genetic 
interchange between stock units continues, despite 
high exploitation rates. In light of this, management 
of fishing mortality rates on the offshore resource 
becomes an issue of increasing importance. 
There is also increasing information on movements 
of lobster larvae, the distribution and behavior of 
newly settled and juvenile lobsters, concentrations 
of egg-bearing females, and the occurrence of long- 
distance homing behavior in American lobster both 
in the northern Gulf of Maine and southern New 
England waters. Some progress has been made in 
roughly delineating stock structure with the help of 
larval dispersion, hydrodynamic, and migration stud- 
ies (NEFSC, 1993). Interpretation of these data, how- 
ever, is tentative because migratory habits of larger 
lobsters appear extensive and may transcend the 
boundaries that some researchers attempt to draw 
solely on the basis of larval distribution. Despite 
many years of larval and postlarval lobster monitor- 
Bannister, R. C. 1997. The Centre for Environment, Fisher- 
ies and Aquaculture Science, Lowestoft Laboratory, Pakefield 
Road, Lowestoft, Suffolk, England NR33 OHT. Personal 
commun. 
ing, a definitive stock-recruitment relation has yet 
to be determined, although ecological knowledge has 
been enhanced. The relative importance of the off- 
shore lobster resource to recruitment in shoaler wa- 
ters of the Gulf of Maine or other areas must be as- 
sessed. We need to know the degree of interchange 
between the two lobster groups in order to refine 
stock assessments. 
Acknowledgments 
We greatly appreciate the help of M. P. Armstrong 
and S. X. Cadrin with initial data collation, and the 
data mapping assistance received from T. B. Hoopes 
in cooperation with MassGIS. R. A. Cooper assisted 
with 1969-71 field activities, including lobster tag- 
ging. Tagging assistance during 1984-85 was pro- 
vided by M. Borgatti, D. McKiernan, M. Syslo, and 
J. O’Gorman. 
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