Improving techniques for broodstock conditioning of Pacific Geoduck Clams
This research is aimed at finding which factors promote maximum fecundity in broodstock Pacific Geoduck Clams (Panopea generosa) reared in a hatchery setting. The effects of various temperature, salinity, and nutritional regimes on gonad development were investigated. The ranges of temperature and salinity were selected to reflect those typical of an estuarine environment in British Columbia (7 to 19°C and 17 to 29‰ respectively).
A temperature of 11°C was optimal with >90% of the clams maintaining ripe gonads with high numbers of oocytes and frequent spawns. Gonads remained ripe at 7°C, but spawning was inhibited. Temperatures above 15°C resulted in gonad degeneration. Salinities of 20‰ or lower were lethal to broodstock while gonad and gamete development were inhibited at a salinity of 24‰ compared to 29‰. The feed type (various combinations of Isochrysis sp., Chaetoceros muelleri, and Dunaliella tertiolecta) did not have significant impacts on gonad development, but overfeeding (>5 billion cells of Isochrysis sp. equivalent per day) had negative impacts on gamete production. The results of this study will be important in improving gamete production (and ultimately, larval production) in commercial-scale Pacific Geoduck Clam hatcheries.
Improving techniques for broodstock conditioning of Pacific Geoduck ClamsThis research is aimed at finding which factors promote maximum fecundity in broodstock Pacific Geoduck Clams (Panopea generosa) reared in a hatchery setting. The effects of various temperature, salinity, and nutritional regimes on gonad development were investigated. The ranges of temperature and salinity were selected to reflect those typical of an estuarine environment in British Columbia (7 to 19°C and 17 to 29‰ respectively).A temperature of 11°C was optimal with >90% of the clams maintaining ripe gonads with high numbers of oocytes and frequent spawns. Gonads remained ripe at 7°C, but spawning was inhibited. Temperatures above 15°C resulted in gonad degeneration. Salinities of 20‰ or lower were lethal to broodstock while gonad and gamete development were inhibited at a salinity of 24‰ compared to 29‰. The feed type (various combinations of Isochrysis sp., Chaetoceros muelleri, and Dunaliella tertiolecta) did not have significant impacts on gonad development, but overfeeding (>5 billion cells of Isochrysis sp. equivalent per day) had negative impacts on gamete production. The results of this study will be important in improving gamete production (and ultimately, larval production) in commercial-scale Pacific Geoduck Clam hatcheries.
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