FISHERY BULLETIN: VOL. 71. NO. 1 



in this report: 1) long-term captive herring 

 held 6 months before sampling began in Feb- 

 ruary and terminated in June when the supply 

 of test fish was exhausted, 2) short-term captives 

 which consisted of herring held 2 weeks before 

 being bled, and 3) wild herring that were taken 

 when available. The captive herring were held 

 in seawater which was pumped from the ocean 

 through the tanks and which approximated the 

 temperature of natural seawater. The water 

 temperature was recorded at the site of capture 

 in each instance. 



A blood sample was taken from the heart of 

 each herring and preserved in a modified Alsev- 

 er's solution for serological studies; a microhe- 

 matocrit was determined and a morphology slide 

 made for each herring. The herring were mea- 

 sured for total length, weighed, sexed, marked, 

 and frozen for reference. All herring were ex- 

 amined for gross parasitism. 



The hematocrits and morphology slides were 

 made of blood taken by direct heart puncture 

 with a heparinized 75 mm x 1.3-1.5 mm outside 

 diameter capillary tube. A small drop of blood 

 from the tube was placed on a microscope slide, 

 the tube sealed with plastic clay, and the smear 

 made. The tubes were centrifuged in a micro- 

 hematocrit centrifuge for 31/2 min at 11,000 rpm 

 and read in a microcapillary reader. Slides were 



air-dried and stained by either the Wright's or 

 Wright-Giemsa staining method. Distilled wa- 

 ter was used as a diluent for the Wright's and 

 Giemsa stains. Cells were examined under oil 

 immersion and photographed at 800 and 1250 

 powers. Hematocrits were measured as the vol- 

 ume percent of packed red cells to the total blood 

 column. (The term "hematocrit" is used in this 

 paper, although Widmark (1970) has suggested 

 the term be replaced with "packed cell volume") . 

 I classify herring erjrthrocytes according to 

 the stage of development in the peripheral blood 

 as erj^hroblasts, early polychromatics, middle 

 polychromatics, late polychromatics or mature 

 cells, depending upon their size and the amount 

 of polychromasia present. These stages are de- 

 scribed in Table 1. Reticulocytes cannot be iden- 

 tified readily without vital staining so are not 

 included in Table 1. There are variations in 

 individual herring in the size and shape between 

 and within cell stages and the amount of poly- 

 chromasia present is the best indicator as to the 

 series to which the cell belongs. 



RESULTS 



The sample source, date of sampling, inci- 

 dence of inclusion bodies, mean length, standard 

 deviation and range in lengths, mean weight, 



Table 1. — The developmental stages and the average size of erythrocytes in the peripheral 



blood of wild herring. 



Stage 



Description 



Cell measurements! 

 (microns) 



Cytosome 



Erythroblast 



Early polychromatic 



Middle polychromatic 



Late polychromatic 



Mature erythrocyte 



Nucleus 



Round, slightly forger cell than the early polychromatic. Has 7.8 X 7.3 5.9 X 6.2 



a dork blue staining cytoplastn with lightly stained spaces. 

 The round purple-red staining nucleus takes up most of the 

 cell. Erythroblosts ore scarce in normal samples. 



The smallest immature red cell that is normally seen in any 7.8X7.1 4.6X3.3 



quantity. Has a light blue to gray staining cytoplasm and 

 appears round. The nucleus takes up most of the cell. 



Round to slightly oval cell with a gray to light gray-orange 9.5 X 7.0 4.8 X 3.0 



staining cytoplasm. Cell is larger than the early polychro- 

 matic. 



Slightly ovol, has a larger cytoplasm and a smaller nucleus 10.0 X 7.7 4.6 X 2.9 



than the middle polychromatic. The cytoplasm appears light 



orange-yellow. 



Oval, has a slig'htly larger cytoplasm and a slightly smaller 10.3 X 7.7 4.2 X 2.8 



nucleus than the late fjolychromotic. The cytoplosm appears 

 orange-yellow to reddish. Late polychromatic and mature 

 cells have essentially the some appearance with Wright's stain. 



! Measurements based on 25 cells in each stage from a normal wild herring in March. 



'♦'I 



126 



