the bullraked plot was taken December 15, 19U9» Group "B" was not 

 indicated by the sampling (solid line, Fig, 10)- Catch measurements of 

 clams bullraked from each of the four quarters during 1950 also indicated 

 the absence of Group "B" which substantiated the results of the 19U9 

 clamshell bucket census. The 1950 clamshell bucket census taken Septem- 

 ber 6-13 also showed no peak for Group "B" (Fig- 11). 



One explanation for the disappearance of Group "B" in both bullraked 

 and control areas is illegal fishing. Catch measurements from quarter 

 U-B had shown that group was present as late as September 3O5 19U9, in 

 the bullraked area. Clamshell bucket sampling in the control area showed 

 Group "B" was present on November 1, 19U9. Clamshell bucket samples Decem- 

 ber 15 in bullraked area shovred Group "B" was absent. If illegal fishing 

 occurred it must have been between November 1 and December 15, 19U9» 



Reports by shore residents confirm the theory that illegal fishing 

 occurred in the Highbanks area during autumn 19U9'. 



The dotted line in Figure 10 Virould then indicate a lower original 

 population than actually existed. This line would be low by the amount 

 of clams illegally fished from the sampled area. 



CONCLUSIONS 



1, The objective of the present experiment was to determine the relative 

 biological effects of power-dredging as compared with hand-digging on 

 a population of hard-shell clams. The use of the terra "biological 

 effects" should be emphasized since v;e made no attempt to investigate 

 the economic, sociological, or legal phases of this problem. There- 

 fore, the information presented in this report must not be considered 

 as the final ansvrer to the power vs, hand-dig!:er controversy, but 

 rather as information on the biological phase alone. 



Because of the time, effort and expense involved, it was possible 

 to conduct this experiment in only one location. Care must be taken 

 therefore, in applying the results to all areas. Likewise > the fish- 

 ing methods used follov/ed a set pattern necessitated by the size of 

 the test area. Deviation from these fishing methods might also 

 modify the results . 



2, Fishing operations during the summers of 19U9 and 1950 demonstrated 

 the differences in size composition of the catch. Dredges removed 

 principally those clams above 60 mm. in length, whereas bullrakes 

 caught most of those above h^ mm. The effect of this difference on 

 the population over a long period of time is not known. 



3, Underwater photographs failed to show any difference in the surface 

 condition of the tvio fished sections of the plot. Both parts appeared 

 similar to the control area. The unsatisfactory nature of many of the 

 pictures prevented their use as a positive criterion for comparing the 

 two fishing methods. 



2U 



