provide a basis for validating the molt or egg extru- 

 sion predictions. 



TABLE 1. — Summary of molt predictions and subsequent valida- 

 tions for American lobsters sampled and tagged at Arnold's Cove, 

 Newfoundland, 24 June-17 July, 1981. 



Results 



Molt Predictions 



Four of the 11 males (36.4%) and 11 of the 27 

 females (40.7%) with pleopod stages 0-2.0 molted 

 instead of not molting as was predicted (Table 1). 

 Even some with pleopod stage molted. Of the 16 

 females which did not molt, 1 4 extruded eggs, and the 

 2 females which did not extrude eggs had stage 1 

 cement glands, indicating that egg extrusion would 

 not occur. Six out of 21 males (28.6%) with pleopod 

 stages 2.5 and 3.0 did not molt, whereas all with 

 pleopod stages >3.5 and all females with pleopod 

 stages >2.5 did molt (Table 1). Overall, 78.4% of the 

 predictions which could be validated were correct. 

 There was greater success with predicting that molt- 

 ing would occur (89.8% correct predictions) than 

 with predicting it would not (60.5% correct predic- 

 tions). There was no pleopod stage at and below 

 which none molted; however, at stage 3.5 and higher 

 all molted. 



Validations of molt prediction are available for 

 males ranging in size from 73 to 104 mm CL. Except 

 for one animal at 99 mm, it was only for animals 

 smaller than 8 1 mm that any of the predictions were 

 incorrect. The size range for which validations are 

 available for females is limited (75-82 mm CL). 



Egg Extrusion Predictions 



All of 17 females with either stage or stage 1 

 cement glands did not extrude eggs, and all of 7 with 

 stage 3 cement glands did extrude eggs as predicted. 

 However, 2 out of 9 with stage 2 cement glands, which 

 were predicted would lay eggs, did not do so (Table 

 2). Overall, 93.9% of the predictions which could be 

 validated were correct. The 2 females which failed to 

 extrude eggs as predicted, molted, despite having 

 molt stage pleopods. 



Discussion 



There have long been problems associated with 

 growth rate and functional maturity determinations 

 in American lobsters. Reliable data on annual pro- 

 portions molting (or molt frequency) and proportions 

 laying eggs in relation to size are difficult to obtain. 

 Both these parameters are essential in assessing the 

 impact of size limit and/or exploitation rate changes 



'This table does not include 69 females which were ovigerous with old eggs at the 

 time of sampling/tagging, all of which subsequently molted 



Table 2. — Summary of egg extrusion predic- 

 tions and subsequent validations for female 

 American lobsters sampled and tagged at 

 Arnold's Cove, Newfoundland, 24 June- 1 7 July, 

 1981. Sixty-nine (69) females which were 

 ovigerous with old eggs at the time of sampling/ 

 tagging, all of which subsequently molted, are 

 not included in the table. 



in a lobster fishery on yield per recruit and reproduc- 

 tive potential. Such assessments are important to 

 proper lobster fishery management. 



The techniques used here to predict molting and 

 egg extrusion provide new approaches to the study of 

 lobster growth and maturity that have only recently 

 been used in studies of lobster populations. Results 

 of this validation study, however, clearly indicate that 

 caution has to be used in their application. 



In the case of molt prediction it appears that the 

 time of sampling in relation to the molting period is 

 critical. The ideal situation would be a very short 

 annual molting period with sampling just prior to the 

 start of molting when all animals going to molt would 

 have well-developed (stage 3 or higher) pleopods. 

 American lobsters reach the northern limit of their 

 range in Newfoundland waters, and it is probably 

 here that their annual molting period is the shortest. 

 In the Arnold's Cove area, molting starts early in July 

 and is virtually completed by early September. In the 

 present study, 5 out of 1 4 lobsters (all females, Table 

 1), sampled and tagged between 24 June and 17 July 

 1981 and had stage pleopods (for which it was pre- 



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