Gametogenic development and spawning of the razor clam, Zenatia acinaces in northeastern New Zealand

RSNZ Publishing
Publication Type:
Journal Article
New Zealand Journal of Marine and Freshwater Research, 2005, 39 (6), pp. 1287 - 1296
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The potential exists for New Zealand to exploit already established markets for razor clams through development of fisheries or aquaculture industries for the nNew Zealand razor clam, Zenatia acinaces. However, fishery or aquaculture development for Z. acinaces requires an understanding of the reproductive cycle including the timing of gametogenic development and spawning. The reproductive cycle of Z. acinaces was studied over an 11-month period from May 2000 to March 2001 at Kennedy Bay, Coromandel Peninsula using qualitative syanrad histological analysis and quantitative measures of oocytes. Histological abalysis indictaed that Z. acinaces is dioecious between the sexes. Gametogenesis began in June with gametes maturing quickly and by August/September (late winter/early spring) most razor clams were ripe. Spawining began as early as September (spring) although spawning mainly occurred during October. By December (summer) nearly all clams were completely spent. From January 2001 most clams could not be sexed as all residual gametes qwew reabsorbed. Rqazor clams remained in this stage during March 2001. Spawning began when the water temperature was around its lowest c. 15degrees celcius. Monthly mean number of eggs/follicle was sensitive to changes in reproductive development, closely following patterns observed in the qualitative stagings. Patterns of monthly mean oocyte diameters did not adequately describe the spawning events observed in qualitative analyses. Sex ratios were equal over the size range (69-99 mm shell length) of clams that could be sexed. The data presented in this study provides valuable information on the timing of spawning events for Z. acinaces, necessary for developing sustainable management strategies and selecting broodstock for aqauculture.
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