LABORATORY BEHAVIOR OF ADOLESCENT AND ADULT MALES OF THE SNOW CRAB (CHIONOECETES-OPILIO) (BRACHYURA, MAJIDAE) MATED NONCOMPETITIVELY AND COMPETITIVELY WITH PRIMIPAROUS FEMALES

In the laboratory, virgin females of snow crab (Chionoecetes opilio) w ere placed singly with one or two males to investigate mating behavior . Physiologically mature males, both adolescent (i.e., chelae undiffer entiated) and adult (i.e., chelae differentiated), mated with females. Typically, matings comprised a precopulatory period, one or more copu lations, and a postcopulatory period during which the female extruded eggs. Some females copulated after oviposition. In noncompetitive mati ng, adult males of 40-60 mm carapace width had repeated but brief copu lations, while adult males of 120-140 mm carapace width had one long c opulation. In pairs of competing adult males, large body size was an a dvantage both in taking over a female from a rival and in preventing f emale takeover by a rival. However, in competitions between an adult m ale and a larger adolescent male, the adult was more likely to disposs ess his rival or prevent takeover. The variance in mass of ejaculate s tored by females was explained (98%) by total copulatory time and numb er of copulations. Females with two mates obtained more copulations an d larger ejaculate stores than females with one mate, suggesting that interannual variability in ejaculate stores reported for wild females is related to the level of male sexual competition.