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1 May 2008 Egg Extrusion, Embryo Development, Timing and Duration of Eclosion, and Incubation Period of Primiparous and Multiparous Tanner Crabs (Chionoecetes bairdi)
Katherine M. Swiney
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This study compares timing of egg extrusion, embryo development, timing and duration of eclosion, and incubation periods of Kodiak, Alaska, primiparous and multiparous Tanner crabs (Chionoecetes bairdi) reared in identical conditions to determine if and how these variables differ between reproductive states. Female reproductive state (primiparous or multiparous) and dates of egg extrusion were recorded, eggs were sampled monthly to determine egg stage and area, and larvae were collected daily during eclosion to determine timing and duration of eclosion. Primiparous Tanner crabs extruded eggs on average 103 days earlier than multiparous females and embryos developed similarly between groups. Both groups exhibited an embryonic developmental diapause at the gastrula stage, but the length of diapause was approximately 6 months for the primiparous group and 3 months for the multiparous group. This diapause appears to synchronize eclosion. The eggs of primiparous Tanner crabs were significantly smaller than the eggs of multiparous females for a few months after extrusion, but the differences may not be biologically significant. Eclosion was relatively synchronous between the two groups, however the mean eclosion date was 10 days earlier for primiparous females and on average, eclosion took 7 days for primiparous females and 12 days for multiparous females. Primiparous Tanner crabs have an average incubation period of 489 days which is 92 days longer than the average multiparous female incubation period of 397 days. Results of this study clearly illustrate that reproductive cycles differ between primiparous and multiparous Tanner crabs which may result in different reproductive potentials. Differences between primiparous and multiparous Tanner crabs must be understood and included in models for effective stock assessment, fishery management plans, and rebuilding plans.

Katherine M. Swiney "Egg Extrusion, Embryo Development, Timing and Duration of Eclosion, and Incubation Period of Primiparous and Multiparous Tanner Crabs (Chionoecetes bairdi)," Journal of Crustacean Biology 28(2), 334-341, (1 May 2008).[0334:EEEDTA]2.0.CO;2
Received: 27 March 2006; Accepted: 22 August 2007; Published: 1 May 2008

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Chionoecetes bairdi
egg extrusion
embryo development
incubation period
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