A Comparative Study of Blood Chemistry and Respiration in Marine and Freshwater Eels

Abstract

THE EURYHALINE NATURE OF THE EEL has made it the su,bject of numerous s.u.dies designed to explain the various physiological mechanisms which allow the eel to inhabit marine, estuar- ine, and freshwater environments. This is par- ticularly true for the common eel of Europe (Anguilla anguilla) and Jpan (Anguilla jap- onica). The American eel (Anguilla rostrata) has not received as much attention, particularly with regard to basic physiologic measurements. We report here a comparative study of the res- piration and the levels of several blood constit- uents of American eels taken from the three maj,o,r environments this spedes inhabits. MATERIALS AND METHODS The eels utilized in this study were taken from a number of freshwater streams and estu- aries in Connecticut and from Long Island Sound by means of eel pots. All were in the yellow stage (mean length 45 centimeters). Fish used for the determination of the various