October 1966 



COMMEECIAL FISHERIES REVIEW 



25 



Table 2 - Dragging Schedule, Condition Indices, and Dry Weights of Oyster Meats for Cultivation Experiment 1. 1 



Sample 

 Number 



Sample 

 Date 



Lane 



Dry Meat 

 Weight Gramsi 



Condition 

 Index 



Number 

 of Drags 



Drag 

 Date 



Sample 

 Number 



Sample 

 Date 



Lane 



Dr>- Meat 

 Weight Gramsi^ 



Condition 

 Index 



Number 

 of Drags 



Drag 

 Date 



1 



1964 

 July 8 



C 



1 

 2 

 3 



4.4 

 4.2 

 4.4 

 4.5 



8.0 

 7.7 

 7.8 

 7.2 





 

 

 



- 



10 



Sept. 18 



C 

 1 

 2 

 3 



3.0 

 2.6 

 3.1 

 3.0 



4.8 

 4.7 

 5.2 

 5.1 





 1 

 9 

 2 



July 23 



Sept. 17 

 Auq. 20 



11 



Sept. 24 



C 

 1 

 2 

 3 



3.0 

 3.1 

 3.0 

 3.1 



5.2 

 4.9 

 4.6 

 4.9 







1 



10 



3 



J.iily 23 

 Sept. 24 

 Sept. 24 



2 



July 23 



C 



1 



2 

 3 



5.2 

 5.5 



4.1 

 4.9 



9.3 

 8.5 



7.4 

 9.5 







1 

 1 

 1 



July 23 

 July 23 

 luly 23 



12 



Oct. 4 



C 



1 

 2 



3 



3.0 

 3.6 

 3.1 

 3.1 



5.2 

 5.9 

 4.9 

 5.0 



- 



- 



3 



July 28 



C 

 1 



2 

 3 



5.4 

 5.2 

 4.4 

 5.3 



8.3 

 8.4 

 6.5 

 8.9 





 1 

 2 

 1 



July 23 

 July 30 

 [uly 23 



13 



Nov. 9 



C 

 1 

 2 

 3 



3.2 

 3.2 

 3.3 

 3.2 



5.4 

 5.4 

 5.5 

 4.8 



- 



- 



4 



Aug. 6 



C 

 1 

 2 

 3 



6.3 

 4.4 

 3.9 

 4.5 



9.4 

 7.6 

 6.6 

 7.1 





 1 



3 



1 



July 23 

 Aug. 6 

 luly 23 



14 



Dec. 7 



C 

 1 



\ 



3.1 



2.9 

 2.8 

 3.3 



4.5 

 5.6 

 5.5 

 4.2 



- 



- 



5 



Aug. 11 



C 

 1 

 2 

 3 



2.5 

 2.8 

 2.9 

 2,7 



3.8 

 5.2 

 4.8 

 4.6 





 1 

 4 

 1 



July 23 

 Aug. 13 

 July 23 



15 



1965 

 Jan. 5 



C 

 1 

 2 

 3 



3.2 

 3.2 

 3.2 

 2.6 



5.8 

 5.3 

 6.4 

 4.6 



- 



- 



6 



Aug. 20 



C 



1 

 2 



3 



3.2 

 2.2 

 2.8 

 3.3 



5.5 

 4.0 

 5.0 

 4.8 





 1 

 5 

 2 



July 23 

 Aug. 20 

 Auq. 20 



7 



Aug. 26 



C 

 1 

 2 

 3 



2.6 

 2.7 

 2.7 

 2.6 



4.1 

 4.4 

 3.3 

 4.0 







1 

 6 

 2 



July 23 

 Aug. 27 

 Auq. 20 



16 



Feb. 2 



C 

 1 

 2 

 3 



3.0 



3.2 

 2.5 

 3.2 



5.1 

 5.2 

 4.7 

 5.2 



- 



- 



8 



Sept. 4 



C 



1 

 2 

 3 



2.9 

 2.9 

 2.7 

 3.0 



4.7 

 4.8 

 4.6 

 5.0 





 1 



7 

 2 



July 23 

 Sept. 3 

 Auq. 20 



17 



March 1 



C 



1 

 2 

 3 



2.3 

 3.3 

 2.9 

 3.1 



3.9 

 5.1 

 5.1 

 5.1 



- 



- 



9 



Sept. 8 



C 



1 

 2 

 3 



2.7 

 2.6 

 3.0 

 2.8 



5.5 

 5.1 



4.8 

 5.0 







1 

 8 

 2 



July 23 

 Sept. 10 

 Aug. 20 



Mean per oyster 



C 

 1 

 2 

 3 



3.5^ 

 3.4 

 3.2 

 3.4 



5.8 

 5.8 

 5.4 

 5.6 



- 



- 



1/Dry meat weight is given as an average per oyster calculated from samples of 20 oysters. 



2/The mean dry weights per oyster for all samples, July 1964 through March 1965 are calculated for: 339 Oysters - C; 339 Oysters - 1, 

 335 Oysters - 2; 338 Oysters - 3. 



In lane 2 (dragged 10 times) the physical 

 disturbance of oysters produced mass spawn- 

 ing. The condition index declined steadily 

 from the beginning high of 7.8 to a low of 3.3 

 on August 26, but recovered to the highest 

 level of condition shown (6.4) on January 5, 

 1965. Lanes 1 and 3 showed effects of partial 

 spawning and then of more spawning after in- 

 itial dragging; recovery of oysters appeared 

 to be less erratic in these lanes than in the 

 control lane. At the end of the experiment, 

 condition indices of oysters were higher in 

 all dragged lanes than in the undragged con- 

 trol lane; dragging of oysters 10 times, how- 

 ever, was not more beneficial to their condi- 

 tion than less frequent dragging (fig. 8). Drag- 

 ging did not materially increase nnortality. 



In seven surveys, taken during the period 

 from July 23, 1964, to March 13, 1965, 58 

 dead oysters were recorded in two categories, 

 broken shell and other. In the control lane 7 

 (12 percent) were dead, one of which had a 

 broken shell; in lane 2, dragged 10 times, 19 



Fig. 9 - Counts of Pacific oyster spat per shell from the 1964 spat- 

 fail in all lanes of Cultivation Experiment 1. 



