Aspects of multiparous snow crab (Chionoecetes opilio) fecundity in insular Newfoundland waters

Taylor, David M. (David Michael) (1996) Aspects of multiparous snow crab (Chionoecetes opilio) fecundity in insular Newfoundland waters. Masters thesis, Memorial University of Newfoundland.

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Abstract

The fecundity of multiparous snow crab (Chionoecetes opilio) females from eight Newfoundland snow crab management areas is reported. Specimens were obtained between 1983 and 1985 when exploitation of the snow crab resource was at a very high level. Three study areas were virgin, while five were heavily fished. Basic biological data such as size (carapace width) age (shell condition) and mating status (presence of new ejaculate in the spermathecae) of each individual were collected at the time of sampling. Gravid female size ranged from 44 to 85mm carapace width (mean 65.8 mm). Fecundity was positively correlated with size ranging from 8,589 to 103,112 eggs (mean 44,658). Females from virgin areas had a higher size-specific fecundity than did those from exploited areas. Also, females utilizing new spermatophores had a higher size-specific fecundity than did those using old or a mixture of old+new spermatophores. Physical factors such as depth or latitude did not appear to affect fecundity. -- The accuracy of utilizing external grasping marks as indicators of recent mating was investigated. The grasping mark status of females from three sources: nearshore time-series trapping surveys, offshore trapping and offshore trawling surveys was determined and correlated with spermathecal condition as determined by dissection. Grasping marks were found to be relatively reliable indicators of mating frequency/recency, correctly predicting spermathecal condition -70-80% of the time. The proportion of new-shelled multiparous females that had recently mated was 1.5 times that of old-shelled multiparous females. -- Fishery exploitation generally had little effect on the proportion of multiparous females bearing eggs but did have a highly significant negative impact on size-specific fecundity. Part of this effect is likely due to reduced mating frequency in exploited populations which leads to a greater reliance on stored sperm for egg fertilization.

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