Vickers. — Oysters. 205 



Discussion. 



Mr. William C. Adams, Boston, Mass.: I should like to ask Mr. 

 Vickers a question, with respect to this oil pollution. Oil coming in on 

 the surface of the water and precipitated on the clam flats and adjoining 

 areas by reason of the rise and fall of the tide can very easily pollute 

 those areas ; if it remains on the surface of the water it is, of course, very 

 deadly in its effect upon wild fowl. But the point I would like to be in^ 

 formed upon is the extent to which this oil or waste will precipitate and 

 lodge on oyster beds, perhaps a number of feet below the surface of the 

 water. To what extent has your investigation shown that that is the 

 fact? 



Mr. Vickers : This oil pollution destroys the oyster spat, which starts 

 on the surface of the water and goes down gradually. It has tlie same 

 opportunity to destroy any other animal life in the water. It has been 

 noticed down on the beds, on the oyster ground. 



Mr. John N. Cobb, College of Fisheries, Seattle: The oysters were 

 practically all destroyed in San Francisco Bay as a result of the dumping 

 of sludge from the oil tankers. The vessels bring the oil in and take 

 it up to the head of the bay, where they discharge it at the great refineries, 

 and then come down the bay — or used to, at least — and dump the sludge. 

 The sludge works around the beds at low tide, killing the spats that are 

 floating, and affecting the oysters on the bottom. We have had the same 

 trouble in Puget Sound. There we have a tide varying from fifteen feet 

 up to twenty feet, which quite freely exposes many of the beds. Some of 

 them are protected by the artificial dykes, but any oil deposited in the 

 neighborhood of those that are not so protected usually spreads around, 

 gathers on the shells and kills the oysters. 



