occurrence of cod falls between the 6° and 

 8° (at 100 meters) isotherms all over the 

 North Atlantic. Bigelow and Welsh (1925) 

 say that 1.7° to 10.0" encompasses the 

 range, although smaller fish may exceed the 

 upper limit, while Jeffers (1931) gives 5° 

 to 10° as the range. 



Maslov (1944) considers that migra- 

 tions of cod are influenced by hydrography, 

 and Rollefsen (1949) states that mature 

 cod seem to avoid low temperatures, although 

 immature fish are less sensative. 



Templeman and Fleming (1953) con- 

 cluded that a study of eighty-one years of 

 catch statistics could not demonstrate the 

 association of the abundance of cod and 

 temperature, probably because there were 

 too many other variables. But McKenzie 

 and Hachey (1939) found that for a rela- 

 tively short period there was good corre- • 

 spondence between the catch of cod and the 

 magnitude of the intermediate cold layer 

 over the Scotian Shelf. Best landings 

 occurred in years in which this layer was 

 of minimum size. 



Fishermen have fished by the thermo- 

 meter, and in one case at least (McKenzie 

 1936), a government agency has addressed 

 an open letter to fishing captains concern- 

 ing the best temperature in which to catch 

 cod. 



There seems little doubt that cod are 

 influenced by the temperature of the water 

 they frequent and by the temperatures of 

 adjoining bodies of water, but of late 

 there has been a tendency to consider the 

 temperature of the water in which feeding 

 cod are found somewhat secondary to the 

 food supply available (Ancellin 1955; 

 Graham et al. 1954; Hachey, Hermann and 

 Bailey 1954; Lee 1952; Rasmussen 1952, 

 1954a, 1954b, 1955; and Schroeder 1930). 

 Of course, as expressed or implied, the 

 presence and abundance of the food organ- 

 isms may also depend on temperature condi- 

 tions, but here the influence on the cod 

 themselves is secondary. 



McKenzie (1956), in reporting on 

 several years of tagging experiments, re- 

 lates that fish caught a day or so apart 

 in the same area but in water of different 

 temperatures showed different migration 

 patterns — the inference being that differ- 

 ent cod frequent different water. 



Rasmussen (1952) maintains that West 

 Greenland cod prefer to seek shallow water 

 when forced away from the banks by low tem- 

 peratures , but Hjort (1914) mentions a 

 long standing theory, that in warmer years 

 cod come closer inshore than usual. 



And as a fragment of evidence that 

 perhaps differential in temperature is 

 important as it may also be in spawning, 

 Templeman (1953b) found large cod numerous 

 near the border of the below-zero inter- 

 mediate cold l^er. 



To turn to observations for a specif- 

 ic area, on the Grand Bank good catches 

 have been reported from -0.5* (Thompson 

 1936) to 7° (Thompson 1935). But usually 

 the optimum is given as lying somewhere 

 between 0" and 4° in spring (McKenzie 1936; 

 Anonymous 1933, 1935b; Thompson 1935, 1936; 

 Rodriguez M. and Rojo L. 1955; Rodriguez M. 

 and Lopez C. 1954; Templeman 1954), with 

 the lower half of this range being favored 

 (McKenzie 1936, Anonymous 1935b, Thompson 

 1935). 



In summer, 3° to 5° seems most favor- 

 able (McKenzie 1936, Anonymous 1935b, 

 Rodriguez M. and Rojo L. 1955). Most 

 authors agree that smaller cod are caught 

 at higher temperatures both within and but- 

 side these ranges. 



McKenzie (1936) says that on the Nova 

 Scotia Banks in the spring -0.5° to 1.5° 

 gives the best fishing, and that 3° is the 

 upper limit. Others (Anonymous 1933, 

 Thompson 1935) subscribe to this upper 

 limit. In summer the picture is somewhat 

 different. McKenzie cites 2.5° to 5.5°as 

 the best temperature , and Ancellin's 1955 

 selection of a temperature over 1.9" agrees 

 reasonably closely. 



In the Gulf of St. Lawrence tempera- 

 tures run higher, but a limiting value of 

 12° has been given (Anonymous 1935b). 

 Thompson (1943) cites 0.5° to 6", with 2° 

 to 5° as the optimum. Huntsman (1925) 

 gives a wide range of about 0.0" to 10.0*, 

 but says that 4.4° to 7.2° is optimum. 

 Tremblay, fishing experimentally with long- 

 lines (1942) found 8° most productive. 



At West Greenland, in the pelagic 

 long-line fishery at Holsteinborg Deep, 

 2.20" to 2.33° is given by Rasmussen (1954a, 

 1954b), but 3.1° to 4.0° has also been 



