tions. Although deterioration of male gonads was 

 less evident, we noted that the sperm concentra- 

 tion decreased after about 8 wk, presumably as a 

 result of resorption. The mortality rate for oysters 

 repeatedly used for gamete extractions and 

 maintained without food or biological filters in 

 113.6-liter (30-gallon) tanks containing recirculat- 

 ing seawater (25"/o()) at 16.0° ± 1.0°C was about 

 10% during the 8-wk period. 



Because high concentrations and large numbers 

 of gametes can repeatedly be extracted from the 

 gonads of individual oysters without apparent 

 detriment and because gamete extraction ob- 

 viates artificial spawning and its inherent prob- 

 lems, we suggest our method of gamete pro- 

 curement can be useful in many investigations 

 and hatchery situations. Our method also permits 

 repeated use of the gametes of selected oysters, 

 and this together with the possible use of 

 cryopreserved sperm (Staeger 1974) reduces var- 

 iability and increases control and management of 

 hatchery production or biological investigations. 



Acknowledgments 



Thanks are due James Lannan, Raymond Mil- 

 lemann, and James Rybock for their assistance. 

 This work is a result of research sponsored by the 

 Oregon State University Sea Grant College Pro- 



gram, supported by NOAA Oflfice of Sea Grant, 

 U.S. Department of Commerce, under Grant 

 number 04-3-158-4 



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701 



