ABSTRACT 



As part of a general investigation of the potential value of fish blood 

 characteristics to the solution of population and migration problems, a study 

 of modifications induced by environmental and physiological variables has been 

 made. Six blood properties of prespawning and postspawning anadromous 

 alewives (Alosa pscudoharengus) were compared. Changes that could be 

 attributed to fresh-water migration and reproduction were found in only two 

 of these properties ; viz., significant reductions in average serum proteins and 

 chlorides of postspawners. No important differences in average sedimentation 

 rate, erythrocyte fragility, hemoglobin content, or serum electrophoretic pattern 

 were found when fish entering fresh water in May were compared with seaward 

 migrants 1 to 2 months later. Serum electrophoretic patterns were generally 

 similar to those of other elupeoids, with fractious having mobilities comparable 

 with human albumin and human alpha- and beta-globulins, but with little 

 representation in the area of gamma-globulins. Great individual variations in 

 hemoglobin content, total serum proteins, serum chloride, and sedimentation 

 rate were found in alewives both before and after spawning. 



