BLOOD PROPERTIES OF PRESPAWNING AND POSTSPAWNING 

 ANADROMOUS ALEWIVES (ALOSA PSEUDOHARENGUS) 



Carl J. Sindermann and Donald F. Mairs, Fishery Research Biologists 

 Bureau of Commercial Fisheries 



Dramatic changes in certain of the blood 

 characteristics of humans and other higher vei-- 

 tebrates often occur under sucli pliysiological 

 stresses as pregnancy or acute disease. It might 

 be anticipated that lower vertebrates, with less 

 precise control of their internal environment, 

 would exhibit equally profound blood changes as 

 the external medium or physiological conditions 

 vary. As an adjunct to serological studies of 

 fishes being carried on at the Bureau of Com- 

 mercial Fisheries Biological Laboratory, Booth- 

 bay Harbor, Maine, it was considered important 

 to assess the extent of environmental and physio- 

 logical influences on blood proiDerties, particularly 

 those which might be related to serological 

 reactions. 



Erythrocyte antigens, which promise to be of 

 great value in fish population and migration 

 studies, have been examined most extensively in 

 higher vertebrate gi-oups (summarized by Dujar- 

 ric de la Riviere and Eyquem, 1953; Mourant, 

 1054), where they have been found to be genet- 

 ically determined and unmodified by environ- 

 mental variations. Some evidence for genetic 

 determination of fish erythrocyte antigens has 

 lieen otfered by Hildemann (19.50). Seinim com- 

 ponents, which may also provide information of 

 value to population studies, are in some cases 

 subject to modification by other than genetic 

 factors. For example, antibody production in 

 fishes has Ijeen sliown to vary with external tem- 

 perature (Bisset, 1948) and protein fractions of 

 fisli serum to vary in amount in disease (Sinder- 

 mann and Maii-s, 1958). Because of possible in- 

 Huence of nongenetic factors on serological 

 properties, a stud\' of environmental and physio- 

 logical effects on blood characteristics seemed 

 advisable. 



Note. — Approved for publication, Maj- 12. 1960. Fishery Bul- 

 letin 183. 



As part of such a study, this paper is concerned 

 with the manner in which tlie combined stresses 

 of migration from the sea to fresh water and of 

 spawning are reflected in several blood character- 

 istics of the alewife (Alosa pseud oharengus) . 

 The nature and extent of serum changes in pre- 

 spawning and postspawning fish have received 

 particular attention in this investigation, although 

 observations on cellular blood components have 

 been included. 



MATERIALS AND METHODS 

 COLLECTION OF BLOOD SAMPLES 



Prespawning and postspawning alewives were 

 sampled in 1958 and 1959 from two separate ]\Laine 

 spawning runs — Damariscotta Mills and "West 

 Boothbay Harbor. Fish were first sampled in 

 May, as they were about to enter fresh water, and 

 again in late June and July, as they were about 

 to re-enter the sea. In addition to the field 

 .samples, pi-espawning alewives taken from both 

 runs were held without food in live cars and sea- 

 water tanks for 2 months before blood samples 

 were taken, to determine the eifect of starvation 

 on electrophoretic characteristics of the serum. 



The fish were bled by cardiac puncture, using 

 a glass-needle technique developed in this labora- 

 toiy (Perkins, 1957). Blood was collected in 

 screw-top vials as individual samples. Half the 

 samples were collected in vials containing 0.2 

 milliliter of 6-percent sodium citrate solution, and 

 half were collected in vials without citrate. De- 

 teraiinations of hemoglobin content, sedimenta- 

 tion rate, and erythrocyte fragility were made 

 immediately with the citrated samples. Sera 

 from uncitnited blood samples were decanted after 

 expressing from the clots overnight at 4° C. In- 

 dividual serum samples were kept frozen at —20° 

 C. until determinations of chloride content, total 



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