NOTE Sainte-Mane and Carnere: Fertilization of Chionoecetes opilio 



763 



Although our laboratory findings suggest that 

 sperm stored at the first mating is effective for fer- 

 tilizing the second clutch in C. opilio, these findings 

 cannot be indiscriminately extrapolated to the field, 

 for at least two reasons. First, the importance of 

 sperm stores in wild Chionoecetes females might fluc- 

 tuate interannually (Beninger et al., 1988; Paul and 

 Paul, 1992). In the northwest Gulf of Saint Lawrence, 

 the intensity of recruitment to the first benthic in- 

 star of C. opilio varies among years in an apparently 

 recurrent pattern: five consecutive, moderate-to- 

 strong year classes alternate with three consecutive, 

 weak year classes (Sainte-Marie et al., in press, and 

 unpubl. data). Given that adult snow crab are 

 anecdysic and that there exist marked differences 

 between the sexes in size and age at adulthood, re- 

 cruitment pulses cause adult sex ratios and charac- 

 teristics of breeding males to change considerably 

 over time (Ennis et al., 1990; Comeau et al., 1991; 

 Sainte-Marie et al., in press). Thus, in some years, 

 the number or quality, or both, of males available for 

 mating with pubescent females might be limiting and 

 this could conceivably result in a decrease in the pro- 

 portion of primiparous females having received 

 enough sperm to fertilize a second clutch. Second, 

 our laboratory experiments pertain only to a one-year 

 reproductive cycle. However, under some natural 

 conditions female C. opilio incubate their eggs for 

 24-27 months (Kanno, 1987; Mallet et al. 2 , 1993; 

 Sainte-Marie, 1993), instead of the =12-month dura- 

 tion observed in our laboratory and inferred for many 

 wild populations (e.g. Ito, 1967; Watson, 1969; Kon, 

 1980). Mallet et al. 2 suggested that this difference is 

 due to temperature: in the Gulf of Saint Lawrence, 

 egg development would take two years for females 

 in their usual deep-water habitat (-1° to 1°C year- 

 round), but only one year for females that stayed for 

 some time in warmer shallow waters. In the former 

 case, effective fertilization of the second clutch in 

 which stored sperm was used would thus depend on 

 sperm surviving in sufficiently high numbers over a 

 2-year period. Clearly, a better understanding of the 

 interrelations between population and reproductive 

 dynamics, sperm delivery, sperm longevity (viabil- 

 ity), and the duration of sperm storage is necessary 

 before any general statement can be made about the 

 importance of stored sperm to reproductive output 

 in C. opilio. 



2 Mallet, P., G. Y. Conan, and M. Moriyasu. 1993. Periodicity 

 of spawning and duration of incubation time for Chionoecetes 

 opilio in the Gulf of St. Lawrence. Int. Counc. Sea CM. [coun- 

 cil meeting] 1993/K:26, 19. 



Acknowledgments 



We thank Y. Gauthier and M. Belanger for help in 

 the laboratory, and G. A. Lovrich, J.-M. Sevigny, B. 

 D. Smith, and anonymous reviewers for comments 

 on the manuscript. This work was funded by the 

 Quebec Federal Fisheries Development Program. 



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