334 



Pacific herring spawn during the spring and their eggs attach to material in 

 the intertidal zone where they would be exposed to both floating oil and oil 

 dispersions obtained by mechanical or chemical means. Kuhnhold (l!t70, p. 8- 

 10) working with the Atlantic herring and other fishes and several types of 

 crude oil found that toxic components are dissolved from oil films injuring larve 

 and younger stages of floating eggs. He noted that even if the concentration of 

 dissolved compounds are sublethal to eggs, the embryos might he injured and the 

 hatched larve were even less resistant. The study emphasized the variability in 

 results between tests.using the various crude oils and the difference in toxicity 

 to various stages of the life cycle of herring, as well as between similar life 

 stages of different species of flsh. For example, herring larve were less resistant 

 and plaice larve were more resistant tlian cod larve of the same age. 



Kuhnhold (1970, p. 10) also observed that herring larve were unable to avoid 

 oil contamiaiated water, especially mixtures of oil and chemical disi)ersant. He 

 concluded that the chemo-receptors seem to be blocked very quickly at the first 

 contact with oil components, and thereafter the larvae entered and crossed 

 well defined milky clouds of even highly concentrated oil disi)ersions with re- 

 sultant high mortality. Other studies (FAO, 1070; Tarzwell, 1970, itp. 260-267; 

 U.S. Senate, 1971, pp. 207-208) aLso reveal that oil dispersant and crude oil 

 mixtures are much more toxic than the oil alone and even more toxic than the 

 oil dispersants alone. 



Recent experiments with Prudhoe Bay crude oil and Pacific herring (Per- 

 sonal communication by S. D. Rice to D. R. Evans, 1971) demonstrated that mi- 

 nute amounts of the water soluble fractions were taxic to newly hatched larvae. 

 Eggs incubated in dilutions of the water-oil mixture which had been filtered to 

 remove all but the microscopic suspended immiscible water-oil droplets resulted 

 in a higher percentage of unsuccessful hatches than among the controls. 



Several studies (James, 1926; Kuhnhold, 1969, 1970; Chipman and Galtsoff, 

 1949; Mironov, 1967, 1968, 1969a, b, c) have demonstrated that various oils in- 

 cluding crude oil are toxic to several species of marine fish eggs and larvae. The 

 toxic concentrations ranged from 1 ppm to 2x10* ppm. There have not been suf- 

 ficient studies, however, to describe the long-term effects of sublethal levels of 

 oil pollution. 



One possibly serious effect of oil disjiersed over wide ocenn areas could arise 

 from the fact that chlorinated hydrocarbons such as DDT and dieldrin are 

 highly soluble in oil films. Measurements of the effects of a natural slick in 

 Biseayne Bay, Florida, showed that the concentration of a single chlorinated 

 hydrocarbon (dieldrin) in the top one millimeter of water containing the slick 

 was more than 10 thousand times higher than in the underlying water (M.I.T., 

 1970, p. 142). Parker (1971, p. 51) commenting on the worldwide distribution of 

 pesticides noted that the poor solubility of many of these substances in water 

 suggests that they may concentrate in surface slicks on the ocean, where they 

 may .spread rapidly over great distances. He concluded that such a mechanism 

 of transport would increase in efficiency in the presence of oil slicks, which have 

 been increasing steadily world-wide since the advent of tankers. 



Winds and ocean currents bring abcmt a convergence and retention of surface 

 concentrations of hydrt>carbons in the subarctic and eciuatorial convergence zone.s, 

 such as the Sargasso Sea. Blumer (1969, p. 6) reported that nets sampling the sea 

 surface layer were fouled with oil and collected a larger volume of tar-like 

 material than of Sargassum weed. 



Campbell and Martin (Personal communication to D. R. Evans from W. J. 

 Campbell and S. Martin, 1971) report the presence of an anti-cyclonic gyre as a 

 feature of the oceanic and ice circulation of the Beaufort Sea. They suggest a 

 strong case can be made for the high probability that once an oil spill enters 

 the ice pack it will become part of the sy.stem, circulate around the gyre and 

 diffuse into and around the gyre. 



A somewhat .similar convergence situation may have been re.sponsible for a 

 1970 oil pollution in Gulf of Alaska waters. The report (I'.S. Dei)artment of the 

 Interior, 1970) concerning this Kodiak oil pollution incident noted that the oil 

 could have been legally discharged on the higli seas beyond the ."O-niile limit 

 .specified by the International Convention for Prevention of Pollution of the Sea 

 by Oil. Amendments to the Convention now being ratified will limit the rate of 

 discharge to a total of 1/15,000 of a ship's loading capacity i)er balla'^^t voyage. 

 As in the past, compliance with such regulations will be voluntary: the Swedish 

 Coast Guard, for example, has declared itself incai)able of ascertaining tlmt no 

 more than (>0 liters per mile have been released during passage of a ship (Boos, 

 1970). 



