Boothroyd and Ennis: Reproduction in Homarus amencanus transplanted northward 



667 



hatching by sometime in September, around the time 

 autumn cooling begins. The other, which had 0.3 yolk 

 remaining and a PEI of 470 at the end of June, would 

 probably have hatched by early August. This was the 

 only specimen for which hatching as much as 4 or 5 

 weeks in advance of autumn cooling was a possibility. 

 However, extensive plankton sampling (130 15-min 

 tows with aim diameter net) conducted near the sites 

 where lobsters were released in St. Michael's Bay, from 

 28 July to 22 August 1986, and from 18 July to 30 

 August 1987, failed to produce lobster larvae. 



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

 ing August ranged from around 9°Ctol0.5°C. Assum- 

 ing temperature in the surface layer was around 15°C, 

 at which lobster larvae will reach Stage IV in 25 days 

 (Templeman 1936), it is possible that larvae hatching 

 in early August would be in Stage IV at the end of 

 August and ready to settle by mid-September. Larvae 

 hatching in late August would be exposed to temper- 

 atures below 10 °C well in advance of reaching Stage 

 IV. At 10°C, it takes 2 months from hatching to Stage 

 IV; and at 5°C, larvae generally die without reaching 

 Stage IV (Templeman 1936). Caddy's (1979) considera- 

 tion of the influence of seasonal temperature regime 

 on survival of lobster larvae indicates poor chances of 

 survival if larvae have not reached Stage IV by the end 

 of August. Any larvae hatching in St. Michael's Bay 

 in late August-early September appear to have little 

 chance of reaching Stage IV and settling in the area. 

 The 1988-90 diver-collected samples involved 12 dives 

 totaling about 30 diver hours searching at the Indian 

 Arm and Goose I. sites. Not a single small lobster was 

 found, suggesting there had been very little if any 

 recruitment since lobsters were transplanted in 1982. 



The possibility that the lobsters transplanted to St. 

 Michael's Bay will become a self-sustaining population 

 is remote. While the portion of females with ripe 

 ovaries that actually extrude has increased substantial- 

 ly during this study, many of these lose all or most of 

 their clutch of eggs before the following summer. Of 

 those females that carry their eggs for at least a year, 

 very few have eggs ready for hatching sufficiently early 

 in the summer that any larvae are likely to settle in 

 the area. Any local recruitment that might occur would 

 be too little and too irregular to support a fishery for 

 lobsters in St. Michael's Bay. 



Citations 



Aiken. D.E. 



1973 Proecdysis, setal development, and molt prediction in the 

 American lobster (Homarus amencanus). J. Fish. Res. Board 

 Can. 30:1337-1344. 

 Aiken. D.E., and S.L. Waddy 



1976 Controlling growth and reproduction inthe American 

 lobster. In Avaulk, J.W. Jr. (ed.), Proc, 7th Annu. meet, 

 world maricult. soc, p. 415-430. Louisiana St. Univ. Press, 

 Baton Rouge. 



1980a Reproductive biology. In Cobb, J.S., and B.F. Phillips 

 (eds.), The biology and management of lobsters, vol. 1, Phys- 

 iology and behavior, p. 215-276. Academic Press, NY. 



1980b Maturity and reproduction in the American lobster. In 

 Anthony, V.C, and J.F. Caddy (eds.), Proc, Canada-U.S. 

 workshop on status of assessment science for N.W. Atlantic 

 lobster (Homariis americanus) stocks, p. 59-71. Can. Tech. 

 Rep. Fish. Aquat. Sci. 932. 



1982 Cement gland development, ovary maturation, and re- 

 productive cycles in the American lobster, Homarus ameri- 

 canus. J. Crustacean Biol. 2:315-327. 



1986 Environmental influence on recruitment of the American 

 lobster. Homariis americamis : A perspective. Can. J. Fish. 

 Aquat. Sci. 43:2258-2270. 



1989 Interaction of temperature and photoperiod in the regula- 

 tion of spawning by American lobsters. Homarus americanus. 

 Can. J. Fish. Aquat. Sci. 46:145-148. 

 Caddy, J.F. 



1979 The influence of variations in the seasonal temperature 

 regime on survival of larval stages of the American lobster 

 {Homarus americanus) in the southern Gulf of St. 

 Lawrence. Rapp. P.-V. Reun. Cons. Int. Explor. Mer 175: 

 204-216. 



Conan, G.Y. 



1986 Summary of session 5: Recruitment enhancement. Can. 

 J. Fish. Aquat. Sci. 43:2384-2388. 

 Cooper, R.A., and J.R. Uzmann 



1980 Ecology of juvenile and adult //oma7-(is. /reCobb, J.S., 

 and B.F. Phillips (eds.). The biology and management of 

 lobsters, vol. II, p. 97-142. Academic Press, NY. 



Ennis, G.P. 



1981 Fecundity of the American lobster, Homarus americanus, 

 in Newfoundland waters. Fish. Bull., U.S. 79:796-800. 



1984a Incidence of molting and spawning in the same season 

 in female lobsters, Homarus americanus. Fish. Bull, U.S. 

 82:529-530. 



1984b Comparison of physiological and functional size-maturity 

 relationships in two Newfoundland populations of lobsters 

 Homarus americamis. Fish. Bull., U.S. 82:244-249. 

 Perkins, H.C. 



1972 Development rates at various temperatures of embryos 

 of the northern lobster {Homarus americanus Milne- 

 Edwards). Fish. Bull., U.S. 70:95-99. 

 Templeman, W. 



1936 The influence of temperature, salinity, light and food con- 

 ditions on the survival and growth of the larvae of the lobster 

 {Homarus americanus). J. Biol. Board Can. 2:485-497. 



1940 The life history of the lobster. Newfoundland Dep. Nat. 

 Resour., Serv. Bull. (Fish.) 15, 42 p. 



