Large males matter: Low sperm reserves in female snow crab (Chionoecetes opilio) off Newfoundland, Canada

Abstract

Large, male snow crab (Chionoecetes opilio) off Newfoundland and Labrador were heavily exploited throughout their range from 2015 to 2018 leading to biological concerns about the possibility of sperm limitation within portions of the stock. To address this, primiparous females were sampled from six sites off the island of Newfoundland to gather data on their overall reproductive health (e.g., seminal receptacle load, SL, and clutch weight) at the end of this heavily exploited period. Snow crab females had low SLs in comparison to long-term monitoring at nearby sites in the Northern Gulf of St. Lawrence but were similar to historic observations from the Eastern Bering Sea. Seminal receptacle loads were significantly influenced by the female’s carapace width, time since mating (represented by sampling month), as well as site-specific characteristics of the male population (ratio of most competitive males in the population and male time since terminal molt). Clutch weight was significantly influenced by the female’s carapace width, as well as the average size of sexually mature males and the average time since terminal molt of adult males. Our findings show the potential for sperm limitation to occur in populations depleted of large-male snow crab and by extension for excessive fishing of males to diminish reproductive capacity of the stock. These findings highlight the importance of maintaining conservative exploitation rates for snow crab that protect a substantial proportion of large adult males in order to preserve reproductive capacity.