EFFECT OF CRUDE OIL POLLUTION ON OYSTERS 
145 
tion in 1933, having a total average daily output of 6,961 barrels. In this parish 
most of the wells are not located on land, but are situated in the open waters of Lake 
Barre, Lake Pelto, and vicinity, which constitute one of the most important oyster- 
producing regions of the State. Pollution of the water has occurred as the result of 
oil-well operations, and coincident with this condition there has been a high mortality 
of oysters particularly during the winter of 1932-33 and to a lesser degree during the 
previous winter. The aggregate losses of the oyster planters, alleged to have been 
caused by oil-well operations, have been estimated at several hundred thousand 
dollars. 
In January 1933 the Louisiana Department of Conservation received reports of 
an extensive and serious mortality of oysters in the Lake Barre and Lake Pelto 
region, which were corroborated by immediate field surveys of its Bureau of Research 
and the State Department of Health. The chemical studies of pollution and subse- 
quent field and laboratory experiments conducted by these departments are reported 
briefly by Gowanloch (1934). Similar chemical and biological field investigations 
were also made by chemists of the Texas Co. and by Dr. C. E. Coates, Dr. A. R. 
Cboppin, and Dr. W. H. Gates of the chemistry and zoology departments of Louisiana 
State University. In May 1933 the cooperation of the U. S. Bureau of Fisheries 
was requested by the Louisiana Department of Conservation, following which, field 
studies were made by Dr. H. F. Prytherch in May, June, and September of the 
oyster mortality in Terrebonne Parish in relation to oil-well operations in this region. 
At the Bureau’s laboratories in Washington, D. C., and Beaufort, N. C., a series of 
experiments have been conducted by the authors to determine the effect of different 
grades of crude petroleum and accompanying brine waters on the survival, feeding, 
and food of the oyster. 
There is no doubt that unavoidable pollution of water by oil and bleed water 
incidental to drilling operations constitutes a serious danger to local oyster, shrimp, 
and fishing industries from the point of view of a fisherman, it being immaterial 
whether pollution has actually destroyed the stock of fish and shellfish or rendered 
them unmarketable on account of oily taste and emaciated condition of the flesh. 
In both cases the industry sustains economic losses. Of course, in case of oyster or 
other mollusks there is a possibility of transplanting the stock to other areas unaffected 
by pollution. So far as the Louisiana coastal section is concerned, this appears to 
be only a palliative, for it is but a question of time until the development of oil 
fields will spread all along the coast and most of the oystermen in the State sooner or 
later will face the problem which at present confronts the industry in Timbalier and 
Terrebonne Bays and Lake Pelto, the sites of the present extensive drilling operations. 
The questions to which the oyster industry desires to receive a competent 
answer can be formulated as follows: Whether the unusual mortality which occurred 
in Louisiana in 1932-33 is attributable to the discharge of oil and bleed water, and 
how further development of the oil resources of the coastal section may affect the cultiva- 
tion of oysters. The marine biologist called to provide an answer finds himself in a 
difficult situation. As often happens in the case of an unusual mortality among fish 
or oysters, he is requested to investigate the cause or causes of it several weeks or 
months after death has occurred, and when the conditions responsible for the mor- 
tality have already changed or disappeared. There is a general and well understand- 
able tendency on the part of a layman to attribute his troubles to unusual activities or 
events that occurred in the affected area. The concurrence of the two phenomena, 
however, does not constitute in itself a proof that one is the cause of the other. 
