Boothroyd and Ennis Reproduction in Homarus amencanus transplanted northward 



665 



The other two PEIs were 108 and 127 (0.8 and 0.7 yolk 

 content, respectively). Even at 10°C, well above the 

 temperature in St. Michael's Bay beyond September, 

 it was estimated these broods would not be ready to 

 hatch until late December-early January. 



Temperature 



Bottom temperature at 7 m in St. Michael's Bay drops 

 below 0°C in late November, remains around -1°C 

 throughout the winter, and rises above 0°C in early 

 June (Fig. 4). Summer warming is rapid. Temperature 

 reaches 9°C between mid- and late- July and peaks at 

 just over 10°C in late August. By mid-September, 

 autumn cooling is underway and temperature starts to 

 drop rapidly around the end of September. At Com- 

 fort Cove, where the transplanted lobsters originated, 

 sub-zero temperatures prevail for only about 2 months 

 in late winter (Fig. 4). Summer warming begins in late 

 April-early May and reaches a slightly higher peak at 

 around 11°C in late August. Autumn cooling begins 

 somewhat later and proceeds more slowly. In St. 

 Michael's Bay, transplanted lobsters are exposed to a 

 similar range in temperature as at Comfort Cove, but 

 to a substantially lower mean temperature during most 

 of the year. 



Discussion 



The very low incidence of new-shell lobsters in the 1986 

 Goose I. sample indicates few molted in summer 1985 

 when they were transplanted. This was most likely due 

 to molt inhibition caused by handling-induced stress, 

 possibly including wide temperature fluctuations, dur- 

 ing transplant. The high incidence of new-shell lobsters 

 at Goose I. in 1988, and the substantial shift to larger 

 sizes among the Indian Arm lobsters (transplanted in 

 1982) by 1986, indicate the transplanted lobsters ac- 

 climated over time and resumed molting despite the 

 lower temperatures in St. Michael's Bay. 



All nonovigerous females examined during the study 

 had advanced ovaries developing for extrusion in the 

 summer they were sampled. All of these had full 

 seminal receptacles indicating they mated at the last 

 molt. However, only 1.8% (2 out of 24 examined in 

 1989) had advanced pleopod cement gland development 

 indicating extrusion was imminent. Some ovigerous 

 specimens with recently-laid eggs were observed each 

 year. This suggests most nonovigerous females that 

 were going to extrude each summer had done so by the 

 time our samples were collected. These amounted, 

 however, to only 23% (A'' 104) of the females (excluding 

 old-egg ovigerous) examined at Indian Arm from 1987 

 to 1990, and 22.5% (A^ 40) of those examined at Goose 

 Island in 1989 and 1990. In 1991, this percentage in- 

 creased to 66.7% {N 6) and 77% (A^ 13) in the Indian 

 Arm and Goose I. samples, respectively. Advanced 

 pleopod setal development among the ripe nonovi- 

 gerous females that were examined in 1989 and 1990 

 indicated 62% would soon molt. 



