was 21 ol^ at one station where the bottom was mud with rocks and shells, 

 although at two other stations having bottoms in the same category no 

 breakage was observed (Pratt, 19^0) o 



Breakage of Undersized Clams 



We examined broken shells in bottom samples to determine the break- 

 age of clams below the legal size of U7-U8 mm. length. We found no 

 evidence that this breakage vfas important in either test area, nor was 

 there evidence of extensive breakage of clams below 60 mm, which had been 

 left in the dredge area. 



Smothering 



Fishermen thought that one or both types of fishing might stir up 

 the bottom to such an extent that some clams would be buried beyond the 

 depth at which they could survive. Observations during the bottom sam- 

 pling revealed very few recently dead clams in either plot, thus, in this 

 experiment neither type of fishing caused significant smothering mortality 

 to those clams left on the beds. 



Effect of Fishing Upon Setting and Set Survival 



Each experimental plot vras divided into quarters which were fished 

 successively during the summer to detect the effect of fishing at differ- 

 ent times in relation to setting. Unfortunately, practically no setting 

 of clams occurred in the test plot during 19U9 or 19^0, and therefore no 

 results were obtained. Bottom sampling in 19U9 obtained a total of seven 

 spat in the control area, five in the bullrake area, and six in the 

 dredge area. No spat vrere found in 1950, 



Effect of Fishing Upon the Physical Characteristics of the Bottom 



We examined bottom samples each year for evidence of silting, scour- 

 ing and mixing o Surface conditions were practically identical in the 

 test areas and in the control one to three months after fishing. This 

 was substantiated by the underwater photographs . The top one to two 

 inches of soil was uniformly yellow mud or silt throughout the test plot. 

 Below this was a 5-6 inch layer of black sandy mud in which the clams 

 live, and below that clay which supported no life. The general appear- 

 ance of these layers was similar in all three areas in 19U9 but in the 

 two test areas the clay and sandy-mud layers were mixed more than in the 

 control. No difference in extent of mixing was observed in clamshell 

 bucket samples from the dredged and from the raked areas , In 1950 the 

 control area showed more mixing of the clay and sandy-mud layers than it 

 had in 19U9j although mixing in the fished areas was still more proncinced 

 than in the control. 



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