mates of lengths of gestation and lactation also 

 trend downward, but the year-to-year differences 

 are not statistically significant. As discussed 

 above, the balance of evidence favors the (rela- 

 tively nonvarying) estimates based on Method 2. 



Although adequate data for estimating sex 

 ratio and proportion of total females which were 

 reproductive in 1971 and 1972, using the methods 

 employed here, or for estimating pregnancy rate 

 using Method 2, are not available because of 

 selection of adult females for dissection, the 

 estimates of pregnancy rate (using Method 1) for 

 those two years are included in Table 5. The 

 sample for 1971 is too small to allow direct statis- 

 tical comparison with the estimates for later 

 years, but the 1972 estimate is not significantly 

 different from the estimates for 1973, reinforcing 

 the suggestion that a major shift in population 

 structure or (more likely) in degree of representa- 

 tiveness of the kill or the sample occurred in 1974. 



In summary, the balance of evidence indicates 

 that, in management of the dolphin/tuna situa- 

 tion, changes in the structure of the dolphin kill, 

 per se, should not be taken to necessarily mean 

 that parallel changes in reproductive rates have 

 occurred. The changes more likely represent 

 sampling artifacts caused by changes in the fish- 

 ing and dolphin rescue operations. 



Literature Cited 



Bailey, N. T. J. 



1959. Statistical methods in biology. English Univ. 

 Press, Ltd., Lond., 200 p. 

 PERRIN, W. F., J. M. COE, AND J. R. ZWEIFEL. 



1976. Growth and reproduction of the spotted porpoise, 

 Stenella attenuata, in the offshore eastern tropical Pacific. 

 Fish. Bull., U.S. 74:229-269. 



WILLIAM F. PERRIN 

 RUTH B. MILLER 



priscilla A. Sloan 



Southwest Fisheries Center 



National Marine Fisheries Service, NO A A 



La Jolla, CA 92038 



THE UPTAKE, DISTRIBUTION, AND 



DEPURATION OF 14 C BENZENE AND 



,4 C TOLUENE IN PACIFIC HERRING, 



CLUPEA HARENGUS PALLAS I 



This note is a sequel to Korn et al. (1976), where 

 uptake, distribution, and depuration of 14 C ben- 

 zene were examined in striped bass, Morone 

 saxatilis, and northern anchovy, Engraulis mor- 

 dax. Like benzene, toluene is a prevalent, water- 

 soluble, and toxic monoaromatic component of 

 petroleum and associated products. According to 

 Anderson et al. ( 1974a), toluene is second only to 

 benzene as the most abundant aromatic oil com- 

 ponent in the water-soluble extracts of southern 

 Louisiana and Kuwait crude oils (6.75-3.36 \s\l 

 liter benzine; 4.13-3.62 /u,l/liter toluene, respec- 

 tively). 



Although levels of the volatile aromatics are 

 thought to be low in areas subject to chronic oil 

 exposure, few actual measurements have been 

 made. Further, if fish can accumulate benzene and 

 if energy is required to metabolize, detoxify, and 

 depurate these aromatics, long-term physiological 

 and population effects are possible. 



In this study, a comparison of the uptake, dis- 

 tribution, and depuration of 14 C benzene and 14 C 

 toluene, at a low sublethal concentration [100 

 parts per billion (ppb)], was undertaken to deter- 

 mine which of these prevalent aromatics may pose 

 the greatest problem. It was hypothesized that, 

 although toluene is less soluble in seawater (An- 

 derson et al. 1974a), it may be more toxic and 

 exhibit greater accumulation levels and persis- 

 tence. Our previous work with striped bass and 

 northern anchovy indicated other tissues that 

 should be examined, such as kidney, pyloric caeca, 

 gonad, and intestine, and in the present compari- 

 son, residues in the additional tissues were mea- 

 sured. Pacific herring, Clupea harengus pallasi, 

 were selected as test animals because of their im- 

 portance as estuarine and nearshore forage fish for 

 many important recreational and commercial 

 species, including striped bass and chinook salm- 

 on. 



Methods 



Pacific herring were obtained from a San Fran- 

 cisco Bay bait dealer and were transported di- 

 rectly to the Tiburon Laboratory dock. The fish 

 were acclimated under test conditions for at least 2 



633 



