286 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



ROBINHOOD COVE 



—1 1- 



FALLS COVE 



Figure 5. — Growth curves for groups of clams planted in Robinhood Cove and in Falls Cove, smoothed by moving 

 averages of three. Oiigin of clams was as follows: 1, Western Beach; 2, Meetinghouse Cove; 3, Sagadahoc Bay; 

 4, Bedroom Cove. 



significantly different growth rates when trans- 

 planted to areas of different growth conditions. 



The importance of environment as opposed to 

 heredity in affecting the growth rate of clams is 

 emphasized by these results. If heredity were 

 the cause of the differences in growth rates in 

 various areas, we should expect clams that grew 

 fast in their native beds to continue to grow fast 

 when transplanted. Likewise, slow-growing clams 

 would be expected to continue their slow rate of 

 growth after transplanting. Instead, the growth 

 rates of clams in this experiment varied with new 

 environments. For example, Bedroom Cove 

 clams, which grew only 3.55 mm. in their native 

 environment, grew 18.36 mm. in Sagadahoc Bay. 

 At the same time, Sagadahoc Bay clams, which 

 grew 14.48 mm. in their native area, grew only 

 2.42 mm. when transplanted to Bedroom Cove. 



EFFECT OF ORIGINS ON GROWTH RATES 



Analysis of variance tests by areas (see appendix 

 B, table B-2) also show that there are significant 

 differences in the mean growth of groups of clams 

 within each test area. This result might be 

 expected because of the spread in the growth 

 curves (figs. 4 and 5). The growth curves for 

 clams from Meetinghouse Cove were higher than 

 for other groups in each of the four test areas 

 where these clams were planted. The analysis 

 of variance summarized in appendix B, table B-3, 

 shows that the F value was reduced from 13.0 to 

 6.0 by omitting clams from Meetinghouse Cove. 

 It is also apparent that Sagadahoc Bay clams 

 contributed greatly to the differences within each 

 test area because their grow^th rate was consistently 

 lower than that of the other groups. 



Since clams from Meetinghouse Cove appeared 



