EFFECTS OF BENZENE (A TOXIC COMPONENT OF PETROLEUM) 

 ON SPAWNING PACIFIC HERRING, CLUPEA HARENGUS PALLASI 



Jeannette W. Struhsaker 1 



ABSTRACT 



When female Pacific herring were exposed to low (parts per billion) levels of benzene for 48 h just prior 

 to their spawning, a significant reduction occurred in survival of ovarian eggs and resultant embryos 

 and larvae through yolk absorption. The reduction in survival of ovarian eggs was approximately 

 10-25%, for embryos from fertilization to hatching, 26%, and for embryos and larvae through yolk 

 absorption, 43%. Exposure to benzene also induced premature spawning and resulted in aberrant 

 swimming behavior and disequilibrium in adults of both sexes. 



The maximum accumulation of 14 C-labeled benzene and/or metabolites in ovarian eggs (14 times 

 initial concentration in water in 24-48 h; 1.4 /il/g from 0.1 /id/liter) was greater than in later egg and 

 larval stages as measured in other experiments. 



Conservatively estimating the total reduction in survival in these experiments to be approximately 

 50% through yolk absorption, I surmise that the effect of exposing spawning herring to only one toxic 

 component of petroleum could have a significant effect on the population. The fish in these experiments 

 were exposed to relatively high parts per billion levels, but they were exposed for a relatively short 

 period (48 h); it is probable that in the estuary, if chronically exposed over a longer period of time to low 

 parts per billion levels of aromatic components, the populations could be seriously affected. 



When the spawning female herring is compared with other life history stages, we find that the 

 spawning stage is clearly the most sensitive of those tested. If fishes prove generally to be most 

 sensitive to petroleum components during their spawning seasons, fishery management decisions 

 should take this factor into consideration in protecting the resources. 



In studies of pollutant effects on marine or- 

 ganisms, emphasis should be placed on critical or 

 sensitive life history stages. With this in view, 

 research on petroleum effects on fish has been 

 directed more recently toward egg, embryo, and 

 larval stages (Kiihnhold 1969, 1972; Evans and 

 Rice 1974; Struhsaker et al. 1974). Results in 

 many studies revealed that fish egg and larval 

 stages were surprisingly resistant to crude oil and 

 water-soluble and aromatic fractions of crude oil. 

 Some of this resistance in fish is probably at- 

 tributable to the presence of enzymes for 

 metabolic detoxification of components with 

 ensuing rapid depuration and physiological 

 homeostasis (Lee et al. 1972; Neff 1975; Korn, 

 Hirsch, and Struhsaker 1976, footnote 2). 



I have observed, as expected, that the effects of 

 exposure of monoaromatics such as benzene are 

 more severe at all life history stages if fishes are 



'Southwest Fisheries Center Tiburon Laboratory, National 

 Marine Fisheries Service, NOAA, 3 150 Paradise Drive, Tiburon, 

 CA 94920. 



2 Korn, S., N. Hirsch, and J. W. Struhsaker. 1976. The uptake, 

 distribution, and depuration of 14 C-benzene and 14 C-toluene in 

 Pacific herring (Clupea pallasi). Unpubl. manuscr. 



otherwise stressed by environmental extremes or 

 are in poor "condition" from inadequate nutrition. 

 On this basis it is suggested that the female at 

 time of spawning may be the most sensitive stage 

 to toxic oil components. In herring, for example, 

 the fish often feed poorly for some time prior to 

 spawning and have low fat and energy reserves 

 associated with the production of eggs (Blaxter 

 and Holliday 1963). Anadromous fishes or fishes 

 such as herring which migrate into estuaries for 

 spawning may also be exposed to environmental 

 extremes, particularly to changes in salinity, 

 which produce additional stress. Further, since 

 aromatics are highly lipid-soluble, it might be 

 expected that benzene would accumulate to high 

 levels in ovarian eggs. These factors could lead to 

 significant reductions in fecundity and serious 

 consequences for populations over long chronic 

 exposures. 



The purpose of this experiment was to examine 

 the effect of benzene on female Pacific herring, 

 Clupea harengus pallasi Valenciennes, just prior 

 to spawning. We have also studied benzene effects 

 on other life history stages of the herring 

 (Struhsaker et al. 1974; Korn et al. see footnote 2; 



Manuscript accepted September 1976. 

 FISHERY BULLETIN: VOL. 75, NO. 1, 1977. 



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