EFFECT OF OIL POLLUTION ON MARINE AND WILD LIFE 173 



from gas wastes with a concentration of 1 part in 400,000 killed 

 yellow perch in 12 days.^ It may be pointed out that the chemical 

 nature of this tarry matter probably differs from the waste oil from 

 oil-burning steamers. 



There is considerable difference of opinion among investigators 

 regarding the toxic effect of oily discharges. One states* that the 

 amounts of petroleum and certain other oils that are sufficient to 

 cause any deleterious effects upon oysters, other than oyster larvae, 

 are surprisingly large. On the other hand, Dr. Thurlow C. Nelson, 

 an authority on the culture of oysters, maintains that oil, gallon 

 for gallon as thrown out, is the most destructive to aquatic life 

 of all foreign substances now entering our coastal waters.^ 



EFFECTS OF OIL ON FISH, SHELLFISH, AND FOWL 



Fish, shellfish, and fowl are affected quite differently by oil. So 

 far as the fish are concerned, pollution by oil not only imparts an 

 obnoxious taste, unfitting them for the market, but the gear used 

 in the' fishing industry is befouled and injured. One investigator 

 doubts that there is any real proof that oil directly destroys adult 

 fish. He states that the effect of oil on fish may be twofold* — (1) 

 the direct effect on the fish themselves and (2) the indirect effect 

 as shown by changes in- environment, food, and migratory habits. 

 He suggests that with regard to migi'atory fish the presence of 

 oil may deflect them from the coastal waters, and thus affect both 

 the spawning and the fishing industry. As just pointed out, the 

 indirect effect is believed to be brought about largely through the 

 changes that take place in their environment affecting spawning 

 grounds, food, and migratory habits. Unsuitable environment, such 

 as would result from oil waste, may be the direct cause of driving 

 these fish to other waters; or the same effect may be produced 

 indirectly because the smaller fish and the aquatic organisms that 

 serve as their food supply have either been destroyed or driven 

 away. 



In connection with the direct effect on fish, the authors desire to 

 state that at least in one instance fish were found struggling in 

 an inclosed body of water badly polluted with oil, apparently suf- 

 focating and unable to right themselves and swim away. The 

 harbor master at Bridgeport, Conn., has seen bluefish and mackerel 

 dead in large numbers on the inner side of the inner breakwater, 

 and he can account for this only by the fish coming in contact with 

 the polluted river waters. He stated that boats coming into Bridge- 

 port with large numbers of live cod on board now close the tank 

 holes before entering the harbor. Ordinarily the holes would be left 

 open to insure a free circulation of water for the fish. It was 

 found, however, that when Bridgeport harbor was entered with these 

 holes open over two-thirds of the cod died. It is probable, how- 

 ever, that other industrial wastes besides oil are responsible for 

 much of the damage done. 



» Marsh, United States Geological Survey, Water Supply Papers 186-192, 1907, p. 337. 

 * Personal communication to the authors. 



" Personal communication to the authors. Doctor Nelson's more complete statement is 

 given later In this paper. 



