the low end of the range, cod seem to be 

 skirting a dangerous margin, for a differ- 

 ence of only a fraction of a degree can 

 mean the difference between thriving fish 

 and dead fish. And actually, probably 

 somewhat in the neighborhood of 15° is the 

 upper limit for cod of appreciable size. 



Bull (1936, 1938, 1952) established 

 by experiments that cod can perceive 

 changes in temperature of as little as 0.05° 

 and of salinity as small as 0.17°/oo. 

 Since his findings in these experiments 

 show results for cod very similar to those 

 for other teleosts, we may extrapolate from 

 another experiment in which cod were not 

 tested and assume that cod can detect dif- 

 ferences in pH on the order of 0.05. 



1933. Cod investigations. Ann. Rept . 

 Newfoundland Fish. Res. Comm. 2(2): 

 71-77. 



1935a. Cod investigations. Proc. 1931- 

 1933. N. Am. Counc . Fish. Inv. 2: 

 19-20. 



1935b. Cod investigations. Proc. 1931- 

 1933. N. Am. Counc. Fish. Inv. 2: 

 31-35. 



1953. Summary of research work by Nor- 

 way in Subarea 1 in 1952. (from 

 Fiskeridirektoratets Havorskningsin- 

 stitutt, Bergen). Int. Comm. N.W. 

 Atl. Fish. Proc. 3(3): 41-45. 



We may conclude as Jensen (1952a) 

 did, that much valuable work has been done, 

 but that much remains to be done in the 

 future. 



BIBLIOGRAPHY 



ABBOTT, C. C. 



1871. Notes on fresh-water fishes of 

 New Jersey. Am. Nat. 4: 99-117. 



BEAUGE, L. 



1937. Recherches Francaises faites dans 

 le secteur Nord-Ouest et particu- 

 lierement \ Terre-Neuve depuis l'annee 

 1934. Rapp. et Proc. -Verb. 105 (3): 

 3-4. 



BIGELOW, H. B., AND W. W. WELSH 



1925. Fishes of the Gulf of Maine. 

 Bull. U. S. Bur. Fish. 40 (1): 

 1-567. (Bur. Fish. Doc. 965) 



ALANDER, H. 



1951. Cod. Swedish Investigations. 

 Ann. Biol. 7: 115-116. 



1952. Fisheries hydrography in the 

 Baltic. Rapp. et Proc. -Verb. 131 

 (9): 61-62. 



ANCELLIN, J. 



1955. Researches, carried out onboard 

 the French oceanographic vessel 

 "President Theodore Tissier" in the 

 Newfoundland area, April-May 1954. 

 Int. Comm. N.W. Atl. Fish. Ann. Proc. 

 5(3): 39-41. 



ANONYMOUS 



1911. The spawning of the cod. Rept. 

 Sci. Invest. Northumberland Sea Fish. 

 Comm. for 1910: 24-25. 



BIGELOW, H. B. , AND W. C. SCHROEDER 

 1953. Fishes of the Gulf of Maine. 

 First revision. Fish. Bull, of the 

 Fish and Wildlife Service No. 74, 

 vol. 53: 1-577. 



BLEGVARD, H. 



1926. Dansk Fiskeritidende No. 25. 

 [From Jensen 1952a] 



BONNETT, D. D. 



1939. Mortality of the cod egg in rela- 

 tion to temperature. Biol. Bull. 

 76 (3): 428-441. 



BRICE, J. J. 



1897. A manual of fish-culture. Gov't 

 Printing Office, Washington, D. C. , 

 340 pp. Also in Rept. U. S. Fish 

 Comm. for 1897, vol. 23; 1-340. 



1932a. Cod investigations. Proc. 1921- 

 1930 N. Am. Counc. Fish Invest.. 1: 

 10-14. 



1932b. Cod. Proc. 1921-1930 N. Am. 

 Counc. Fish. Invest. 1: 53-54. 



BRITTON, S. W. 



1924. The body temperature of fishes. 

 Contr. Canadian Biol., N. S. 1 (22): 

 415-418. 



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