DISCUSSION 



According to Scarratt (1964), the period of lobster hatching 

 and location of hatching areas may be determined by examin- 

 ing the temporal and spatial presence of stage I larvae. A 

 comparison of station densities in 1975 revealed that sub- 

 stantially more stage I individuals were collected at stations 

 3 and 13. In 1976, stage I larval densities were relatively high 

 at stations 1,5, and 6. Our results agreed with those obtained 

 by Marine Research, Inc.," indicating peak larval densities 

 in the environs of Rocky Point. Again in 1977, stage I larval 

 density was highest at station 1. Forty-nine percent of the 

 first stage larvae we collected that year were- captured at this 

 site. In contrast to our 1976 findings, the total catch of stage 

 I larvae was less at stations 5 and 6 in 1977. 



The relatively high percentage of fourth stage larvae ob- 

 tained in our study may be due to differential availabilty to 

 capture by molt stage (Herrick 1896; Templeman and Tibbo 

 1945; Scarratt 1973). Alternatively, high catches of fourth 

 stage larvae may represent transport by currents from other 

 hatching areas. With the existence of a net counterclockwise 

 advection in Cape Cod Bay (O'Hagen footnote 9), late stage 

 larvae may be recruited from areas north and offshore from 

 those studied. In late July 1976, prevailing south-southwest 

 winds with concomitant decline in surface water temperature 

 probably produced an offshore movement of surface water 

 with a possible transport of lobster larvae. A similar situation 

 existed in 1977 during a period of reduced larval density. 



Our limited sampling indicated there was minimal depth 

 stratification of larvae during the daylight. Templeman (1937), 

 Templeman and Tibbo (1945), Sherman and Lewis (1967), and 

 Scarratt (1973) reported that the majority of lobster larvae 

 during the daytime are collected at the surface. 



Hatching initiated in mid-June at water temperatures of 

 approximately 14°C (surface) and 8°-9°C (bottom) and ter- 

 minated by mid-August. The period of occurrence of larvae in 

 the water column ranged from 46 to 62 d. There was consider- 

 able variability between years in seasonal larval densities and 

 percent composition of molt stages. Maximum abundance of 

 lobster larvae in daytime occurred in surface waters in July. 

 Sampling at shoal water stations yielded few larvae whereas 

 the areas of Brant Rock (Stations 1 and 2), High Pine Ledge 

 (Station 3), and from the mouth of Plymouth Bay to Rocky 

 Point (Stations 5 and 6) produced greatest numbers of total 

 larvae. Higher numbers of stage IV larvae were collected than 

 were expected relative to the number of stage I larvae obtained 

 and considering the expected mortality between stages I-IV. 



Wind-generated currents may be an important transport 

 mechanism affecting dispersion of lobster larvae and ultimate 

 distribution in surface waters (Templeman 1937; Templeman 

 and Tibbo 1945; Squires 1969; Caddy' 2 ). We observed on 

 several occasions over the 4 yr that when a sampling trip was 

 preceded by several consecutive days of offshore winds, e.g., 



from the southwest, we noted that our catch was comprised of 

 atypically fewer lobster larvae, substantially less crab larvae, 

 and abnormally large numbers of terrestrial flying insects. 



ACKNOWLEDGMENTS 



We extend special thanks to the following: Boston Edison 

 Company (BECo) funded the study and provided wind data; 

 the Pilgrim Administrative-Technical Advisory Committee for 

 overseeing the investigation; Robert Anderson of BECo for 

 his continued support throughout all aspects of the study; 

 and to numerous Division staff: Shirley G. Mitchell, Lewis 

 Emerald, James Fair, and Raymond Heintz for their assistance 

 in field collections; Donald Maclsaac aided in computer pro- 

 gramming; W. Stephen Collings for his helpful sugges- 

 tions; Eleanor Bois who typed the manuscript; and W. Leigh 

 Bridges, Christine Sheehan, and Susan Faria for editorial 

 review of the text. 



LITERATURE CITED 



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1969. A new midwater trawl for sampling discrete depth horizons. J. 

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1971. The shelter related behavior of the lobster, Homants americanus. 

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U.S. Comm. Fish. 15:1-252. 

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52 



