port caused by wind driven currents and generally counter- 

 clockwise tidal currents in Buzzards Bay (Anraku 1964). The 

 presence of both stage I and stage IV larvae at Station K was 

 an indication of hatching in the vicinity of the entrance of 

 the Canal and possible recruitment of larvae from an area 

 north of the Canal. 



It appeared that onshore winds concentrated lobster larvae 

 at nearshore stations. This was substantiated by the higher 

 densities of late stage larvae found in northern Buzzards Bay 

 following southwest winds and at nearshore stations in Cape 

 Cod Bay following northeast winds. 



Effects of Cloud Cover 



A total of 65.7% of our tows was made when cloud cover 

 was 25% or less and 71% of the total larvae were collected 

 when cloud cover was minimal (25% or less). The average den- 

 sity of larvae collected under clear skies, hazy, 25% cover, 

 50% cover, and 75% cover was 7.3, 8.2, 7.1, 10.5, and 8.4 lar- 

 vae/1,000 m 3 , respectively. Under completely overcast condi- 

 tions, the average density decreased dramatically (2.8 larvae/ 

 1,000 m'). Only 6.4% of the larvae collected were obtained 

 when cloud cover was 100% . 



Water Temperature, Larval Hatching, 

 and Intermolt Periods 



Stage I larvae were collected in Buzzards Bay waters ranging 

 in temperature from 14.0° to 25.0°C. Stages II, III, and IV 

 were collected at temperatures ranging from 16.5° to 25.5°C. 

 Larvae collected in the Cape Cod Canal were found in water 

 ranging in temperature from 12.5° to 23.5°C. First stage larvae 

 were collected at 12.5°-22.0°C, second stage were collected at 

 14.5°-22.5°C, third stage at 16.5°-22.5°C, and fourth stage in 

 temperatures ranging from 17.0° to 23.5°C. Larvae were col- 

 lected in Cape Cod Bay at the following surface water temper- 

 atures: Stage I, 10.3°-21.1°C, stage II, 14.0°-20.0°C, stage III, 

 14.0°-20.0°C, and stage IV, 14.5°- 20.5 °C. The highest water 

 temperature at which larvae were collected was 25.5°C and the 

 lowest water temperature recorded when larvae were collected 

 was 10.3°C. 



Estimated average larval intermolt period was determined 

 from the number of days between initial collection of a given 

 stage and first collection of the succeeding stage. Buzzards 

 Bay larvae took an average of 23.2 d to molt from stage 1 into 

 stage IV in water temperatures ranging from 14.0° to 22.0°C. 

 Templeman (1936b) reported development times of 11-26.5 d 

 for larvae to molt into stage IV at this temperature range. 

 Cape Cod Canal larvae required an average of 25 d to reach 

 stage IV at temperatures ranging from 12.5 ° to 22.5 °C. Based 

 on Templeman's data it would take 10.5-78 d for larvae to 

 complete their third molt when held at these temperatures. 

 Cape Cod Bay larvae averaged 35 d to molt into stage IV at 

 10.3°-20°C; predicted development times under laboratory 

 conditions were 12-49 d (Templeman 1936b). 



Salinity 



Observed salinities of 23.3 to 35.5°/oo were within the toler- 

 ance range of < 20°/ oo to 42.5 /oo (Templeman 1936b; Scarratt 

 and Raine 1967; McLeese 1956). 



Discrete Depth Sampling 



Sixty-six discrete depth tows were made at nine stations in 

 1977. Four depths (surface, 3, 6, and 9 m) were sampled. A 

 two-way analysis of variance (ANOVA) (Snedecor and Coch- 

 ran 1967) was performed on data grouped into two categories: 

 Canal stations (4, 5, and 6) and open water stations (Stations 

 1 , 2, 3, F, H, and K). Results showed that at the Canal stations 

 there was no significant difference with depth at the 5% level 

 (F = 1.04; df = 3, 9); the probability of capturing larvae was 

 uniform at all depths due to mixing in the Canal (Collings et al. 

 footnote 4). However, at open water stations, significantly 

 higher surface densities were obtained (F = 6.74; df = 3, 9; P 

 < 0.05). 



Scarratt (1973) reported significatly higher catch rates for 

 stage I larvae in surface waters. Bibb et al. (1983) obtained 

 similar results in Block Island Sound in 1977 and 1978. 



Larval Deposition in Cape Cod Bay 



Tidal patterns in the study area result in transport of signifi- 

 cant numbers of larvae hatched in Buzzards Bay and the Cape 

 Cod Canal into Cape Cod Bay. It was conservatively estimated 

 that canal water flows into Cape Cod Bay for 3 h per tidal cy- 

 cle at a rate of 2,095.4 m'/s. The average Cape Cod Canal lar- 

 val density for each year was multiplied by the total volume of 

 water flowing into Cape Cod Bay during each larval season. 

 Estimates of the numbers of larvae entering Cape Cod Bay for 

 the years 1976, 1977, and 1978 were 13.5 million, 26.0 million, 

 and 9.2 million, respectively. 



Matthiessen and Scherer (1983) calculated that approxi- 

 mately 7.3 million larvae were deposited in Cape Cod Bay dur- 

 ing the period 7-20 June 1976. Our estimate for the same 

 period was 9.2 million larvae. 



ACKNOWLEDGMENTS 



Thanks are extended to David E. Pierce and Donald B. 

 Maclsaac for their preliminary computer programming; 

 Captain Shirley Mitchell and Mate Lewis Emerald for their 

 assistance and guidance in our sampling program; H. Arnold 

 Carr, Jay Wennemer, and Elizabeth Amaral for their input 

 and dedication during the early phases of the sampling pro- 

 gram; W. Leigh Bridges for his administrative support; 

 Eleanor Bois for the typing of the final manuscript, and 

 Stephen Hall for his able assistance and guidance during the 

 course of the study. Appreciation and thanks to Philip 

 Dawicki, Julie-Ann Mello, Catherine L. Cooper, Frank 

 Hogan, Thomas Cronin, Paul Duplinsky, and Frederick Reis, 

 without whom the intensive sampling during the summers of 

 1977 and 1978 would not have been possible. 



A special word of appreciation and thanks to Stanley 

 Knight, Captain of the subcontracted vessel, Laitri Ann, for 

 the interest and enthusiasm displayed over 3 yr of neuston 

 sampling in Buzzards Bay. 



A final word of thanks to the Administrative-Technical 

 Committee for their guidance and Canal Electric Company for 

 their willingness to fund and support a study of this type. 



39 



