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Management of the fishery for California sea cucumbers Parastichopus californicus in the Pacific Northwest is limited by a lack of natural growth rate estimates. Growth rates of caged juvenile California sea cucumbers (from Departure Bay, British Columbia) consuming a natural diet for 12 months (September 2008–September 2009) were examined. Growth was low between September and March but significantly increased thereafter, appearing to follow seasonal physiological processes, temperature, and natural sedimentation rates. Over the 12‐month period, whole wet weight in air (WWA) increased by an average of 164%, immersed whole weight (IWW) increased by 251%, and the size index (SI) increased by 85%. Average standard growth rates were 0.267%/d for WWA, 0.346%/d for IWW, and 0.169%/d for SI. Measurement accuracy, effects of body content, and relationships between size and weight metrics are discussed. These findings are an important addition to the knowledge of California sea cucumber biology and are valuable for the stock assessment, fisheries management, and aquaculture of this species. Received January 1, 2011; accepted November 10, 2011

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The molecular mechanisms underlying oocyte maturation in the annelid polychaetes Arenicola marina and Arenicola defodiens were investigated. In both species, a hitherto unidentified hormone triggers synchronous and rapid transition from prophase to metaphase, a maturation process which can be easily reproduced in vitro . Activation of a roscovitine-and olomoucine-sensitive M-phase-specific histone, H1 kinase, occurs during oocyte maturation. Using affinity chromatography on immobilized p9CKShs1 , we purified CDK1 and cyclin B from oocyte extracts prepared from both phases and both species. In prophase, CDK1 is present both as an inactive, but Thr161-phosphorylated monomer, and as an inactive (Tyr15-phosphorylated) heterodimer with cyclin B. Prophase to metaphase transition is associated with complete tyrosine dephosphorylation of the cyclin B-associated CDK1, with phosphorylation of cyclin B, and with dramatic activation of the kinase activity of the CDK1/cyclin B complex. We propose that Arenicola oocytes may provide an ideal model system to investigate the acquisition of the ability of oocytes to be fertilized that occurs as oocyte shift from prophase to metaphase, an important physiological event, probably regulated by active CDK1/cyclin B.

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