modal peak of stage I abundance was not as evident as in 

 Buzzards Bay. The period of exact hatching in the Canal was 

 possibly masked by advection of Buzzards Bay larvae into the 

 Canal with reversal of the tidal cycle. 



Cape Cod Bay larval abundance patterns were similar to 

 those of Buzzards Bay, but occurred several weeks later. Stage 

 I abundance was greatest by the last week of June and stages 

 II, III, and IV were not collected until the second week of 

 June. Larval occurrence extended into September in Cape Cod 

 Bay and stage III and IV larvae were collected as late as 

 October. 



Percent stage composition of larval catches varied both 

 annually and geographically (Table 2). We not«d an increased 

 percentage of fourth stage larvae over the 3-yr study period. 

 Similar patterns in stage IV abundance during 1976-78 were 

 noted by Bibb et al. (1983) and Lux et al. (1983). Ctenophore 

 abundance was relatively high in 1976 and subsequently de- 

 creased over the next 2 yr. Lund and Stewart (1970) found 

 that when ctenophore densities peaked, samples were almost 

 devoid of fish or crustacean larvae. 



The number of lobster larvae collected is dependent, in part, 

 on the number of ovigerous females within the area. The mean 

 carapace lengths (CL) of ovigerous females in Buzzards Bay 

 and Cape Cod Bay were 81 mm and 97 mm, respectively, 

 (Fair 7 ) and the proportion of ovigerous females in research 

 trap catches was higher in Buzzards Bay. Ovigerous females 

 composed up to 14% of the catch in Buzzards Bay but < 1 .0% 

 in Cape Cod Bay. Higher larval densities in Buzzards Bay may 

 reflect higher spawning stock levels. Templeman (1936a) sug- 

 gested that the American lobster attains maturity at a size 



which varies inversely with temperature. Aiken and Waddy 

 (1976) stated that female lobsters matured at a smaller size in 

 the warmer Gulf of St. Lawrence than off southern Nova 

 Scotia. 



Effects of Surface Currents on Spatial Distribution 



During the months of May-September, winds in the study- 

 area were generally southwest and monthly average speeds 

 ranged from 17.7 to 24.1 km/h (11-15 mph) (U.S. Army Corps 

 of Engineers 8 )- Scarratt (1973) noted that winds in excess of 

 24.1-29.0 km/h (15-18 mph) tend to prevent efficient 

 sampling. Our sampling trips were rescheduled if strong winds 

 were forecast; exposed stations were not sampled if winds in- 

 creased appreciably during any sampling day. 



Wind records for the 24-h period prior to sampling revealed 

 that 68.0% of all tows and 76.4% of the tows containing 

 larvae in Buzzards Bay were made when winds were from the 

 southwest. A total of 85.2% of the larvae was found in sam- 

 ples collected when w inds were onshore. 



In Cape Cod Bay, 72% of all tows and 73% of all tows 

 containing larvae were made when winds were from the south- 

 west quadrant, however, only 39% of the larvae were collected 

 during offshore winds. When winds were from the northeast- 

 northwest (on or alongshore) 56.8% of the larvae collected in 

 Cape Cod Bay were obtained in 10 tows. 



Throughout 1976, the continued occurrence of stage I larvae 

 at Stations 3 and 5 suggests that these sites were primary 

 hatching areas. Large numbers of late stage larvae collected 

 at Stations 1, 2, E, and G were possibly due to larval trans- 



'James .1. Fair. Assistant Director. Massachusetts Division of Marine Fish- 

 eries, 100 Cambridge Street, Boston. MA 02202. pers. eommun. 4 September 

 1978. 



•U.S. Army Corps of Engineers Division, New England. 1973. Final environ- 

 mental statement, addition of Unit No. 2, Canal Plant. 2.1, 12 p. U.S. Army 

 Corps of Engineers, Trapello Road, Waltham, Mass. 



Table 2. — Percent stage composition of lobster larvae for three areas for 1976-78. 





Stage 1 



Stags 



: II 



Stage 



111 



Stage 1 



All 



Area 



No. 



Percent 



No. 



Percent 



No. 



Percent 



No. 



Percent 



stages 



1978 





















Buzzards Bav 



575 



J6 8 



237 



15,2 



233 



14.9 



518 



33.1 



1.563 



Cape Cod 





















Canal 



207 



4S.1 



44 



10.2 



69 



16.0 



110 



25.6 



430 



Cape Cod Bay 



60 



5:.: 



6 



5.2 



II 



9.6 



38 



33.0 



115 





842 



39.9 



287 



13.6 



313 



14.8 



666 



31.6 



2,108 



1977 





















Buzzards Ba\ 



1.161 



:- - 



888 



:: o 



1,040 



25.8 



946 



23.4 



4,035 



Cape Cod 





















Canal 



310 



4". 4 



89 



13.6 



60 



9.2 



195 



29.8 



654 



Cape Cod Bay 



544 

 2.015 



81.0 



37.6 



30 



1,007 



4.5 

 18.8 



23 

 1.123 



3.4 

 20.9 



75 

 1,216 



11.2 



22.7 



672 

 5.361 



1976 





















Buzzards Bav 



389 



56.6 



110 



16.0 



123 



17.9 



65 



9.5 



687 



Cape Cod 





















Canal 



498 



34,9 



308 



21.6 



477 



33.4 



145 



10.2 



1.428 



Cape Cod Bay 



32 



6S.I 



1 



2.1 



3 



6.4 



11 



23.4 



47 





919 



42.5 



419 



19.4 



603 



27.9 



221 



10.2 



2,162 



All years 





















Buzzards Bav 



2.125 



33.8 



1,235 



19.6 



1,3% 



22.2 



1.529 



24.3 



6.285 



Cape Cod 





















Canal 



1.015 



40.4 



441 



17.6 



606 



24.1 



450 



17.9 



2.512 



Cape Cod Bay 



636 



3.776 



76.2 



39.2 



37 

 1,713 



4.4 

 17.8 



37 

 2,039 



4.4 

 21.2 



124 

 2.103 



14.9 

 21.8 



834 

 9.631 





38 



