FISHERY BULLETIN: VOL. 75, NO. 1 



Eldridge et al. 3 ). So far as we know, there is no 

 similar study, exposing fish just prior to spawning, 

 for any oil component. 



Benzene was selected for most of our studies on 

 herring because of its relatively high proportion in 

 the water-soluble fraction of crude oil and refined 

 products (Anderson et al. 1974), high solubility in 

 water and relative toxicity (Benville and Korn 

 1974, footnote 4; Korn, Struhsaker, and Benville 

 1976). Monoaromatics were tested individually 

 rather than exposing fishes to the total oil or total 

 water-soluble fraction in order to more specifically 

 delineate physiological responses to a known toxic 

 component. 



Initial research on Pacific herring adults, eggs, 

 and larvae was conducted with high (ppm level) 

 concentrations of benzene (Struhsaker et al. 1974; 

 Korn, Struhsaker, and Benville 1976). Because of 

 the high volatility of benzene, such concentrations 

 would probably occur only briefly after cata- 

 strophic incidents, such as tanker accidents and 

 well blowouts. Subsequently, we tested levels in 

 the low ppb (parts per billion) range as being more 

 representative of chronic exposures and poten- 

 tially more damaging over a long period to marine 

 populations. 



In this study, ripe male and female herring were 

 exposed just prior to spawning to 100 nl/liter (ppb) 

 and 800 nl/liter (ppb) benzene for 48 h. The re- 

 labeled benzene and its metabolites were mea- 

 sured in the ovaries to determine uptake, ac- 

 cumulation, and depuration. Exposure effects on 

 behavior, the mortality of eggs in the gonads of 

 females, and rate of delayed mortality in embryos 

 at hatching and larvae through yolk absorption 

 were also recorded. 



METHODS 



Pacific herring were captured 4 December 1974 

 during the spawning season in San Francisco Bay 

 by a local bait dealer. The fish were captured with 

 a lampara net and wet-brailed from the net into 

 the vessel bait wells. The fish were transported 

 immediately in the bait vessel to the Tiburon 

 Laboratory dock and then transferred to 1,900- 

 liter tanks in the laboratory. Fish were "running 

 ripe" when captured. Because the purpose of these 



3 Eldridge, M. B., T. Echeverria, and J. W. Struhsaker. 

 Manuscr. in prep. The effect of benzene on the energetics of 

 Pacific herring (Clupea harengus pallasi) embryos and larvae. 



4 Benville, P., Jr., and S. Korn. Manuscr. in prep. The acute 

 toxicity of six mono-cyclic aroma tics to striped bass (Morone 

 saxatilis) and bay shrimp (Crago sp.). 



experiments was to expose fish prior to spawning, 

 an acclimation period of only 24 h was allowed. 

 Previous experience with ripe herring has shown 

 that they usually spawn shortly after capture. 



Fish were initially placed in circular tanks with 

 double sand-filtered, open flow seawater at 

 ambient conditions in the bay at the time. Initial 

 handling mortality was negligible. During the 

 experiment, conditions were as follows: salinity, 

 23.0-24.0%o; temperature, 10.0°-11.5°C; oxygen, 

 6.0-10.5 ppm. An ambient benzene concentration 

 was undetectable at the ppb level. Since herring 

 generally feed poorly when spawning, neither 

 exposed nor control fish were fed during the ex- 

 periment. The exposure treatments were as 

 follows: 



Control: nl/liter (ppb) benzene; open flow 

 system, no benzene exposure; approximately 

 100 fish (50 males, 50 females). 



Exposed: 800 nl/liter (ppb) benzene, open flow 

 system, constant exposure for 48 h; ap- 

 proximately 100 fish (50 males, 50 females). 



Exposed: 100 nl/liter (ppb) 14 C-labeled benzene; 

 static system, declining exposure, 48 h; 25 

 females only; linear decrease in benzene 

 concentration to approximately 10% of initial 

 concentration remaining at end of 48 h. 



All benzene exposures were terminated and 

 open flow reestablished in the 100 ppb static 

 exposure tank at the end of 48 h. The static ex- 

 posure of 14 C-labeled benzene was to determine 

 the uptake, accumulation, and depuration of 

 benzene in the gonads of females. The open flow 

 constant exposure and control were primarily to 

 establish morphological and mortality effects on 

 the ovarian eggs and delayed effects on sub- 

 sequent larval development and mortality. 



The behavior of fish was observed before 

 sampling. Subsamples of females were taken daily 

 for 6 days — 2 days during exposure and 4 days 

 after. Fish were removed randomly until 10 

 females were obtained from the control and 800 

 ppb exposure conditions. Five females were 

 removed daily from the static 100 ppb exposure. 

 Concentrations of benzene in the water of all tanks 

 were also measured daily. 



Each female sampled was measured (standard 

 length), weighed (wet weight), and the ovaries 

 dissected out. The ovaries were also measured 

 (total length) and weighed (wet weight); the left 

 ovaries were examined microscopically, the right 



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