above procedure was followed for those sizes be- 

 tween the largest with 100% functionally immature 

 and the smallest with 100% functionally mature 

 (from the data) and the numbers added. The result- 

 ing estimates were 25% at Arnold's Cove and 20% at 

 Comfort Cove. 



Discussion 



This study has demonstrated that, failure on the 

 part of physiologically mature female lobsters to 

 "express" their maturity by extruding eggs is quite 

 common in the wild. Resorption of the mature ovary 

 near the expected time of extrusion appears to be the 

 main reason. Resorption occurs when the molting 

 and reproductive cycles conflict (Aiken and Waddy 

 1976, 1980a, b). These cycles are normally syn- 

 chronized by temperature and photoperiod regimes 

 so that conflict between them is minimized. 

 However, final ovary maturation is disrupted, if it 

 coincides with middle to late premolt, and the ovary 

 is resorbed prior to the impending molt. Not only 

 would this ensure the conservation of energy, but it 

 might also serve to resynchronize the molt and re- 

 productive cycles (Aiken and Waddy 1980b). 



Nonfertilization may also be a cause of resorption. 

 In Jasus lalandii, for example, oviposition will not 

 occur in unfertilized females (Heydorn 1969). While 

 oviposition will occur in H. americanus even if the 

 female has not successfully mated (Aiken and Waddy 

 1980a), it is not clear if this is the rule or the excep- 

 tion. Physiologically mature H. americanus females 

 which are unfertilized (i.e., empty seminal recep- 

 tacles) occur in the wild (Krouse 1973; Ennis 1980). 

 In sampling from January to June 1973 at St. Chads, 

 Bonavista Bay, on the northeast coast of Newfound- 

 land, Ennis (1980) found 6 (11.5%) of 52 

 physiologically mature females to be unfertilized. At 

 Arnold's Cove in August and September 1981, 98 of 

 100 females >79 mm CL were fertilized as deter- 

 mined by the presence of spermatophores in seminal 

 receptacles. While nonfertilization may be a con- 

 tributing factor in some areas, it does not appear to 

 be a major cause of ovary resorption in wild H. 

 americanus. 



A validation study (Ennis 1983) has demonstrated 

 that the cement gland staging technique enables a 

 reliable prediction of whether a female lobster will 

 extrude eggs during the upcoming spawning season. 

 However, caution has to be exercised in applying a 

 functional size-maturity relationship based on these 

 predictions because there is substantial loss of eggs 

 subsequent to spawning. For example, 2 of 15 

 females with well-developed (stages 3 and 4) cement 



glands, indicating extrusion to be imminent, and 1 of 

 6 females with newly laid eggs (all tagged during the 

 24 June to 17 July 1981 sampling period at Arnold's 

 Cove) had molted and were nonovigerous when 

 recaptured prior to the 1982 molting/spawning 

 period. 



There is also substantial loss of eggs other than 

 through molting. Some of this loss may be the result 

 of eggs not being fertilized. Unfertilized eggs do not 

 attach securely and may be lost soon after oviposi- 

 tion, but in some cases a fair number will remain 

 attached for several months (Aiken and Waddy 

 1980a, b). However, it is common for fertizlied eggs 

 to be lost as well (Aiken and Waddy 1980a , b). Nor- 

 mal attrition of properly attached (fertilized) eggs 

 over the 9-12 mo incubation period has been 

 estimated at around 36% (Perkins 1971); however, 

 some females lose up to 100% of their eggs. The six 

 ovigerous females referred to above (i.e., tagged dur- 

 ing 24 June to 17 July 1981 at Arnold's Cove) had 

 apparently normal clutches of eggs when tagged, but, 

 of the five that had eggs when recaptured, four had 

 normal clutches and one had < 200 eggs remaining. A 

 normal clutch for this particular animal, which was 79 

 mm CL, would have been about 10,000 eggs (Ennis 

 1981). Similar observations were made on animals 

 tagged between 1 and 14 August 1981 at Arnold's 

 Cove. Of six females with newly laid, normal-sized 

 clutches of eggs, one had just a few hundred eggs 

 remaining when recaptured. Another female, which 

 had well-developed (stage 4) cement glands, had no 

 eggs but had pleopods covered with cement when 

 recaptured, indicating that eggs had been extruded 

 and subsequently lost (Templeman 1940). 



These observations demonstrate that there is sub- 

 stantial loss of eggs subsequent to extrusion over and 

 above that attributed to normal attrition. This loss of 

 eggs should be taken into account in any assessment 

 of the impact of changes in fishery regulatory 

 measures on reproductive potential (i.e., annual egg 

 production) in a population. 



Acknowledgments 



I am grateful to P.W. Collins who was responsible 

 for collecting the samples and examining the 

 pleopods for molt stage and cement gland develop- 

 ment and to G. Dawe and D. G. Badcock who assisted 

 in the collection of the samples. 



Literature Cited 



Aiken, D. E. 



1973. Proecdysis, setal development, and molt prediction in 



248 



