DIFFERENTIAL BLOOD CELL COUNTS OF ATLANTIC HERRING, 



CLUPEA HARENGUS HARENGUS 



Stuart W. Sherburne' 



ABSTRACT 



In differential blood counts of 200 herring, Clupea haiengus harengiis, the percentages of 

 white cell types and immature erythrocytes in the blood were found to be different from those 

 previously reported in the literature. Herring were sampled from February 1969 through July 

 1969 from the Boothbay Harbor, Maine, and Deer Island, New Brunswick, Canada, areas. 



Immature erythrocytes in wild herring ranged from 6 to 38% with an average of 21; in cap- 

 tive herring they ranged from 2 to 22% with an average of 11. Thrombocytes were the most 

 common type of leukocyte, followed in decreasing order by lymphocytes, neutrophils, baso- 

 phils, and eosinophils in both captive and wild herring. 



The percentage of each white cell type varied greatly between individual herring, but except 

 in one instance, the mean percentage of each white cell type varied little between samples. One 

 group of wild herring was unusual in that neutrophils averaged 21% of the leukocytes in con- 

 trast with an average of 4% neutrophils for three other wild samples and an average of 6.8% 

 neutrophils for four captive samples. 



The percentage of immature red cells varied widely between individual herring, but the 

 mean percentage varied little between wild and captive herring within their respective 

 categories. 



The blood of herring has been studied at the 

 Boothbay Harbor Laboratory to find physiologi- 

 cal indicators of environmental stress that may 

 help us determine causes of fluctuations in suc- 

 cess of year classes. In previous published 

 studies Naumov (1959) reported changes in the 

 differential white cell counts of Atlantic herring, 

 Clupea harengiis hareiigus, from the Barents Sea 

 and from the Greenland Sea in relation to the 

 sexual cycle; Boyar (1962) reported no differ- 

 ences in the occurrence of blood cell types of 

 Atlantic herring, Clupea harengiis harengiis, 

 from the Gulf of Maine that related to length, or 

 that offered any promise as an aging method. 

 The differential white cell counts of herring I 

 examined were different from those previously 

 reported by Boyar and by Naumov. I shall 

 report the results of my studies and discuss pos- 

 sible reasons for those differences. 



' Northeast Fisheries Center, National Marine Fisheries 

 Service, NOAA, West Boothbay Harbor, ME 04575; 

 present address: Maine Department of Marine Resources, 

 West Boothbay Harbor, ME 04575. 



Manuscript accepted April 197.1. 



FISHERY BULLETIN: VOL. 71, NO. 4, 1973. 



MATERIALS AND METHODS 



My analysis is based upon blood samples 

 collected from wild herring obtained from com- 

 mercial fishermen's catches and captive herring 

 held in a tank at the Boothbay Harbor Labora- 

 tory. These data are shown in Tables 1 and 2. 



All herring sampled from Boothbay Harbor 

 were immature. Those from Deer Island were 

 nonspawning mature fish and those from East- 

 port were 95% nonspawning mature fish and 5% 

 immature fish. Captive herring were held in 

 circular tanks having a capacity of 1,325 gallons. 

 These tanks were supplied with unheated sea- 

 water which was pumped directly from the 

 ocean. The water temperature was recorded at 

 the site of capture in each instance. 



Captive herring were fed a diet of canned cat 

 food and commercial fish pellets. This diet was 

 supplemented with natural food which entered 

 the tanks through the water system. This natural 

 food supply varied with the season; barnacle 

 larvae were available in spring, and mollusk 

 larvae were available in summer. 



Slides were made from blood obtained by 



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