Size at Physiological Maturity and Minimum Size at Functional Maturity for Male Dungeness Crabs in Alaska Waters

Size at Physiological Maturity and Minimum Size at Functional Maturity for Male Dungeness Crabs in Alaska Waters

C.L. Worton, D. Urban, K.M. Swiney, Z. Grauvogel, and S. Byersdorfer

Size at Physiological Maturity and Minimum Size at Functional Maturity for Male Dungeness Crabs in Alaska WatersThis is part of Biology and Management of Exploited Crab Populations under Climate Change
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Description

Alaska Department of Fish and Game harvest regulations for Dungeness crab (Cancer magister) set size limits to ensure that males have an opportunity to mate at least once before recruiting to the fishery. In Alaska, the Dungeness crab size limit is based upon studies conducted in British Columbia in the 1960s and it is unknown whether the current commercial size limit of 165 mm carapace width (CW) is appropriate for stocks in Alaska. We determined the size at male physiological maturity and minimum size at functional maturity via field collections and noncompetitive laboratory mating studies using crabs collected from Kodiak Island, Alaska. Physiological maturity was determined by examining males for the presence of spermatophores in the vas deferens. Onset of physiological maturity was observed at 62 mm CW, 50% physiological maturity at 64.6 mm CW, and 100% maturity at 71 mm CW. Laboratory mating studies were conducted to examine male functional maturity, defined as the ability of a male and female to mate, resulting in extrusion of fertilized eggs. A polymerase chain reaction analysis was used to confirm that the putative father contributed to the fertilization of the eggs. Males were functionally mature at a minimum of 112 mm CW, smaller than previously reported. Until functional maturity can be defined in a competitive setting, a full functional maturity schedule is determined, and the importance of small males in the mating of larger females is examined, changing the size limit is not recommended.

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