I 



ORIENTATION OF MIGRATING ANADROMOXJS FISHES 



395 



free CO2 content when the free CO, difference 

 exceeded ().:'> ]>. j). ni. (0.1 mm. of Hjr in terms 

 of CO2 tension). The differences in free CO2 ex- 

 amined ranged from 0.2 p. p. m. CO2 to greater 

 than 4.0 p. p. m. The amount of free CO. in the 

 ■water during these experiments varied from 0.8 

 p. p. m. to 7.1 p. p. m. 



4. The sex of the fish appeared to have no in- 

 fluence on its response to differences in COj con- 

 tent or in temperature. 



T). Explorator_y experiments indicated that vis- 

 ual factors and such factors as velocity and 

 t arbulence can influence orientation. 



G. The fi.'^h did not respond to a difference of 

 1.1 p. m. m. O2 created during experiments. The 

 amount of O2 in the water during the experiments 

 ranged from 10.5 p. p. m. to 10.7 p. p. m. and 

 water temperatures ranged from 15.4° to 19.1° C. 



7. The fish were indifferent to pH differences 

 as large as 0.8 pH unit when associated differences 

 in free CO2 were less than the threshold 0.3 p. p. m. 

 The pH of the water varied from 6.5 to 7.3 during 

 these experiments. 



8. The relative orientative influence of CO2 

 and temperature, when the two factors were in 

 opposition, was shown to depend upon their rela- 

 tive differences of magnitude. A difference in 

 temperature of approximately 2° C. dominated 

 an opposing difference in free CO2 of 2.0 p. p. m. 

 A difference of CO2 slightly in excess of 2.4 p. p. m. 

 balanced the opposite effect of a 2° C. tempera- 

 ture difference. A difference of >7.0 p. p. m. CO2 

 dominated over a temperature difference of 0.6° C. 



S). The behavior of the fish during the experi- 

 ments indicated that the orientation was accom- 

 plished by a nictliod of "trial" involving both 

 movement of the fish and a comparison of in- 

 tensities of stimulations which were successive 

 in time. 



LITER.\TURE CITED 



American Association kor the Advancement of Science. 

 1939. The migration and conservation of salmon. 

 Publ. No. 8, 106 pp. Science Press, Lancaster. Pa. 

 AMERICAN Public Health Association. 



1946. Standard methods for the examination of water 

 aiul sewnge. Ed. '.). 2!1(j pp., illus. New Y<irk. 



P.ULL, Herbert O. 



1930. Studies on conditioned responses in fislies. Part 

 VII. Temperature perception in teleosts. .Tour. Ma- 

 rine Biol. Assoc. United Kingdom (n. s.) 21 (1) : 1-27, 

 illus. 



Chamberlain, F[eedebic] M. 



1907. Some observations on salmon and trout in 

 Alaska. Report of the Commissioner of Fisheries 

 for the Fiscal Year of lOOC with special papers, L'. S. 

 Bureau of Fisheries Doc. No. G27, 112 pp., illus. 

 Chevey, [P.J, [L.] Roui.E. and [M.] Verrieb. 



1927. Sur I'interruption de la montue des Saumon par 

 la diminution de la teneur du cours il'eau en oxygene 

 dis.sous. Coniptes Uendus, I,".\i:nl. Scieiues l.s.'i (2o) : 

 1527-1528. Paris. 

 CiiinESTER, F|loyd] E. 



1!I24. A critical exaniiiiatinii of the cviileiice fur jih.vsi- 

 cal and chemical influences on fish migration. F.ritish 

 Jour. Exper. Biol. 2 : 79-118. 

 i;i.us, II. M.. B. A. Westfall, and Marion D. Ellis. 

 1948. Determination of water quality. U. S. Fish and 

 Wildlife Service, Re.se.-irch Report 9, 117 pp. 



FOEBSTER. R[U.sSELl E. 



1929. Notes on the relation of temperature, hydrogen- 

 ion concentration, and oxygen to the migration of 

 adult sockeye salmon. Canadian Field-Nat. 43 (1) : 

 1-4. 



Fraenkel, GoTTi'WED, aiul Donald L. Gunn. 



1940. The orientation of animals. 352 pp. Clarenden 

 Press, Oxford. 



Jennings, H[erbekt] S. 



1906. Behavior of the lower organisms. 36G pp. 

 Columbia University Press, New York. 

 .Moore, Edward W. 



1939. Graphic determination (if carbon dioxide and 

 the three forms of alkalinity. Juui'. Amer. Water 

 Works A.«sn., vol. ."51, pt. 1. p. -"il. 

 I'oWERS, Edwin B. 



1930. The relation between pH and aquatic animals. 

 Amer. Nat. 64 (693) : 342-366, illus. 



1939. Chemical factors affecting the migratory move- 

 ments of the I'acilic salmon. I'ubl. Amer. Association 

 for the Advancement of Science No. 8, pp. 72-S5. 

 Powers, Edwin B., and R. T. Clark. 



1943. Further evidence on chemical factors affecting 

 the migratory movements of lishes especially the 

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 I'OWERS, Edwin B., ami T. A. Hickman. 

 1928. The carbon dioxide tensions of the Fraser River 

 and its lower tributaries and of certain tributaries of 

 the Columbia River. Puget Sound Biol. Sta. I'ubl. 

 5 : 373-380. 



ItOLT-E, Louis. 



1914. Sur I'inlluence exercee sur la mLuration de mon- 

 t^e du Saumon {Salmo salar L.) par la proportion 

 d'oxygeue dissous dans I'eau des lleuves. Comptes 

 Rendus. L'.Xcad. Sciences 158: 13G4-]3Gt;. Paris. 



1933. Fishes. Their .iourne.vs and migrations. Trans, 

 from the French by Conrad Elpliinstoue. 270 pp.. 

 illus. W. W. Norton and Co., Inc., New York. 



