dieted that molting would not occur that year), had 

 molted when recaptured prior to the molting period 

 the following year. For these animals premolt 

 development must have occurred very rapidly during 

 the 1 98 1 molting period. This indicates that periodic 

 sampling throughout the molting period along with a 

 validation study are required in order to use these 

 molt prediction techniques as a basis for estimating 

 annual proportions molting in a lobster population. 

 The overall success rate with predicting egg extru- 

 sion was much greater than with molt prediction 

 (94% cf. 78%). The small number of incorrect predic- 

 tions may have resulted from loss of eggs rather than 

 failure of the animals to extrude. One of 6 ovigerous 

 females with newly laid eggs that were tagged during 

 the 24 June-1 7 July sampling period had molted and 

 was nonovigerous when recaptured. While egg extru- 

 sion prediction based upon the cement gland staging 

 technique provides a reliable basis for estimating 

 annual proportions laying eggs in a lobster popula- 

 tion, it is clear that such estimates should be ad- 

 justed, using the kind of information that can be 

 obtained from a validation study before being used in 

 an assessment of reproductive potential in a 

 population. 



Ennis, G. P. 



1984. Comparison of physiological and functional size- 

 maturity relationships in two Newfoundland populations 

 of lobsters Homarus americanus. Fish. Bull, U.S. 82: 

 244-249. 



Robinson, D. G. 



1979. Consideration of the lobster (Homarus americanus) 

 recruitment overfishing hypothesis; with special 

 reference to the Canso Causeway. In F. D. McCracken 

 (editor), Canso marine environment workshop, Part 3 of 4 

 Parts, Fishery impacts, p. 77-99. Fish. Mar. Serv. Tech. 

 Rep. 834. 



SCARRATT, D. J., AND P. F. ELSON. 



1965. Preliminary trials of a tag for salmon and lobsters. J. 

 Fish. Res. Board Can. 22:421-423. 

 Waddy, S. L., andD. E. Aiken. 



1980. Determining size at maturity and predicting egg extru- 

 sion from cement gland development in Homarus 

 americanus. CAFSAC (Can. Atl. Fish. Sci. Advis. 

 Comm.) Res. Doc. 80/43, 9 p. 



G. P. ENNIS 



Department of Fisheries and Oceans 



Fisheries Research Branch 



P.O. Box 5667 



St. John's. Newfoundland, Canada A 1C 5X1 



Acknowledgments 



I am grateful to S. L. Waddy for her courtesy and 

 cooperation in teaching P. W. Collins the pleopod 

 and cement gland staging techniques. I am indebted 

 to Collins who, in addition to examining all the 

 pleopods in this study, participated in the field work 

 involved in obtaining samples, tagging, and recovery 

 of tagged animals and provided the data summaries. 

 Assistance with field work was provided by G. Dawe 

 and D. G. Badcock to whom I am also very 

 grateful. 



Literature Cited 



AlKEN, D. E. 



1973. Proecdysis, setal development, and molt prediction in 

 the American lobster (Homarus americanus). J. Fish. 

 Res. Board Can. 30:1337-1344. 

 1980. Molting and growth. In J. S. Cobb and B. F. Phillips 

 (editors), The biology and management of lobsters. Vol. I, 

 Physiology and behavior, p. 91-163. Acad. Press, N.Y. 

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



1982. Cement gland development, ovary maturation, and 

 reproductive cycles in the American lobster Homarus 

 americanus. J. Crust. Biol. 2:315-327. 



Campbell, A., and D. G. Robinson. 



1983. Reproductive potential of three American lobster 

 (Homarus americanus) stocks in the Canadian Mari- 

 times. Can. J. Fish. Aquat. Sci. 40:1958-1967. 



COMPARISON OF PHYSIOLOGICAL AND 



FUNCTIONAL SIZE-MATURITY 



RELATIONSHIPS IN TWO 



NEWFOUNDLAND 



POPULATIONS OF LOBSTERS 



HOMARUS AMERICANUS 



Lobster (genus Homarus) fisheries are characterized 

 by excessive exploitation rates and small, minimum 

 legal sizes in relation to sizes at maturity 

 (Anonymous 1977, 1979). Under such conditions, 

 widespread recruitment overfishing is a distinct 

 possibility and in eastern Canada appears to be the 

 cause of stock collapses in certain areas (Robinson 

 1979). Stock-recruitment relationships as such are 

 poorly known for the genus Homarus; however, since 

 current levels of landings are well below historical 

 levels in most fisheries, it is reasonable to assume 

 that, within the limits of habitat carrying capacity, 

 increased egg production will result in increased re- 

 cruitment. It is clear that increasing the minimum 

 legal size and/or reducing exploitation rates will 

 result in increased egg production within a lobster 

 stock; however, detailed knowledge of size-fecundity 

 and size-maturity relationships is required to pro- 

 perly assess the impact of changes in fishery 

 regulatory measures on annual egg production within 

 a given stock. 



244 



FISHERY Bl'LLKTIN: VOL. 82. NO. 1. 1984. 



