Estrella and Morrissey: Seasonal movement of Homarus americanus 
473 
liberated at station 1) were grouped as southeast (off- 
shore) in direction. All other recapture points, includ- 
ing those within Cape Cod Bay, were grouped as 
northwest (inshore) in direction. Inshore versus off- 
shore travel was tested with chi-square by month of 
recapture for lobsters at large up to one year and 
which traveled more than 3.7 km. Direction of travel 
was biased significantly toward inshore during 
warmer months (Table 5). 
Discussion 
Our findings of greater directed movement toward 
the north and west during summer months is in 
agreement with the summer movement along the 
eastern shore of Cape Cod and into Cape Cod Bay as 
reported by Morrissey (1971). The Cape Cod land- 
mass is interjacent to inshore grounds to the north 
and west and offshore grounds along the edge of the 
continental shelf to the south and east. The overall 
northwest-southeast distribution of recapture points 
suggests an interchange of inshore and offshore 
stocks in the Cape Cod area. Cooper and Uzmann 
(1971) and Uzmann et al. (1977) found that lobsters 
tagged in offshore canyon areas moved into shoal 
water in late spring and early summer, returning to 
deep water in late fall and early winter. Lobsters 
migrating from that offshore area to the inshore area 
of eastern Massachusetts would pass along the east- 
ern shore of Cape Cod. The northwest-southeast pat- 
tern of recapture locations is consistent with move- 
ment to and from the Georges Bank and southern 
offshore canyon area which exhibits a similar popu- 
lation structure to the lobster group which is only 
seasonally available east of Cape Cod. 
Lawton et al. (1984) found minimal movement in 
an inshore tagging study of 4,761 sublegal lobster at 
nearby Rocky Point, Plymouth, Massachusetts dur- 
ing 1970-75. Only 19 lobsters (<1% of returns) were 
retrieved 16 or more km from their release points 
and all 19 were within state territorial waters. A 
study by Fair 6 on legal-size lobster in the same area 
several years later yielded similar results. Additional 
studies affirmed the nonmigratory nature of inshore 
lobsters (Templeman, 1935; Wilder, 1963; Cooper et 
al., 1975; Krouse, 1980; Stasko, 1980; Campbell, 
1982). Ennis ( 1984) noted small-scale seasonal depth 
movements in relation to temperature with lobsters 
moving to shallow water in warmer months and 
deeper water in colder months. More extensive sea- 
sonal migrations were demonstrated by Campbell 
(1986) and Pezzack and Duggan (1986). 
We conclude that lobsters tagged in the present 
experiment are onshore migrants from an offshore 
stock that seasonably becomes “superimposed” on the 
endemic inshore stock. Recapture depths were sig- 
nificantly greater in colder months than during sum- 
mer. The movement of lobsters off southeastern Mas- 
sachusetts is cyclical, with lobsters moving to deep 
water in late fall. Uzmann et al. (1977) found that 
lobsters returned to the continental shelf margin and 
slope in fall and winter. In our study only three lob- 
sters were recaptured during December through 
April, consequently, we did not clearly establish if 
lobsters winter specifically on the edge of the shelf 
or in deep-water areas in general. However, four of 
our lobsters were recaptured in clearly offshore ar- 
eas: at 40°07', 70° 38’, 119 m depth, on 26 September 
1970; at 40°34', 67°37’, 110 m depth, on 9 May 1970; 
at 41°35', 68°25', 55 m depth, on 23 May 1971; and at 
40°15', 70°00’, 95 m depth, on 22 December 1972. The 
occurrences of these recaptures in time, 
depth, and location suggest seasonal move- 
ment to and from the edge of the continen- 
tal shelf between fall and spring. With an 
average recovery rate of only 7.0% of lob- 
sters tagged offshore by Cooper and 
Uzmann (1971), it is probable that sub- 
stantial numbers of our inshore tagged lob- 
sters wintered on the edge of the continen- 
tal shelf. 
Cooper and Uzmann (1971) concluded 
that offshore lobsters actively orient to 
optimum temperature according to season. 
Uzmann et al. ( 1977) provided further sup- 
6 Fair, J. J., Jr. 1977. Lobster investigations in man- 
agement area 1: southern Gulf of Maine. NOAA, 
NMFS State-Federal Relationships Div., Mass. 
Lobster Rep. No. 8, 21 April 1975-20 Apr. 1977, 8 
p. Appendix, 5 p. 
Table 5 
Seasonal distribution of recapture points of lobsters at large up to one 
year and that had traveled more than 3.7 km. 
Direction of travel 
Recapture period 
Number 
inshore 
Number 
offshore 
Total 
X 2 
1st season of release 
July-August 
106 
43 
149 
PcO.0001 
September-October 
59 
15 
74 
PcO.0001 
1st winter of release 
November-May 
11 
5 
16 
P=0.134 
2nd season of release 
June-August 
8 
4 
12 
P=0.248 
Total 
184 
67 
251 
