FISHERY BULLETIN: VOL. 71, NO. 4 



of the cells appeared to show diffusion of 

 nuclear material into the cytoplasm. 



Naumov (1959) reported that the blood of 

 sexually mature Murmansk (Atlantic) herring, 

 Clupea harengus harengus, contained — in 

 decreasing order of relative abundance — lympho- 

 cytes, monocytes, polymorphonuclear leukocytes, 

 and eosinophils. Naumov, like many other 

 authors, did not include thrombocytes in his dif- 

 ferential counts. 



In contrast to Naumov's report, neither Boyar 

 (1962) nor I found monocytes in the Atlantic 

 herring we examined. Jakowska (1956) dis- 

 cussed the confusion regarding the term mono- 

 cyte, and because of the difficulty of recognizing 

 monocytes with certainty, advised caution in in- 

 cluding them as a separate category of teleost 

 blood cell types. Catton (1951), Gardner and 

 Yevich (1969), Hesser (1960), Romer (1949), 

 Saunders (1966, 1968a) and Watson et al. (1963) 

 did not report monocytes in teleost fish species 

 they examined. Romer (1949) stated that mono- 

 cytes, sometimes regarded as a separate cate- 

 gory of white cells, appear to be merely large 

 lymphocytes. I believe Naumov (1959) may 

 have confused monocytes with large lymphocytes 

 or neutrophils for the following reasons: 

 Naumov reported lymphocytes in Atlantic her- 

 ring ranged from 3.5 to 5.6]U, while monocytes 

 ranged from 8.0 to 10.8;U. The lymphocytes in 

 the herring I examined ranged from small (5/j) 

 to large (lOju). Thus, perhaps Naumov's mono- 

 cytes were actually large lymphocytes; however, 

 he stated that during the process of regeneration 

 of the gonads after spawning, there is an increas- 

 ing quantity of monocytes and polymorpho- 

 nuclear leukocytes in the blood evidently acting 

 as phagocytes. Watson et al. (1963) stated that 

 the neutrophil is a possible cause for some of the 

 confusion regarding the existence of a monocyte 

 within teleost blood, especially a neutrophil 

 with a kidney-shaped nucleus. As the photo- 

 graphs in the translation of Naumov's report 

 available to me are not clear and his monocytes 

 and polymorphonuclear leukocytes have nearly 

 the same range of dimensions (8.0 to 10.8ai and 

 8.5 to 14.4jU, respectively) perhaps his phago- 

 cytic monocytes were neutrophils. 



Differential blood counts of herring fry 55-65 

 mm in total length, sampled in June and July 



1971 from Boothbay Harbor, and mature her- 

 ring 290-320 mm in total length, sampled 28 

 October 1972, northeast of Nantucket Shoals, 

 confirm the findings of this study in that throm- 

 bocytes are the most common type of leukocyte 

 in herring blood followed in decreasing order 

 by lymphocytes, neutrophils, basophils and 

 eosinophils. 



This report provides a more accurate descrip- 

 tion of characteristic blood cell differentials 

 found in Atlantic herring and provides a baseline 

 for a systematic study of leukocyte differentials 

 in physiologically stressed herring. 



ACKNOWLEDGMENT 



I wish to thanlc George J. Ridgway for many 

 helpful discussions and constructive criticism of 

 the manuscript. 



LITERATURE CITED 



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Naumov, V. M. 



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