SEAWARD MIGRATION OF CffiNOOK SALMON. 



CONCLUSIONS. 



45 



RATE OF GROWTH. 



An analysis of the data from the Columbia River shows that all of the collections 

 are not strictly comparable, since the rate of growth is markedly variable in different 

 parts of the river. The environmental conditions in different regions of the watershed 

 are so variable that this is not surprising. Therefore the collections have been separated 

 into four groups, each group having been taken under approximately similar conditions. 

 These four groups are as follows: (i) From the main river above the estuary (the estuary 

 is considered as that part of the river below Tenasillihee Island, about i8 miles above 

 Astoria) ; (2) from the estuary exclusive of the collections made under the canneries ; 

 (3) from under canneries in the estuary; (4) from Clackamas hatchery and the Clacka- 

 mas River near the hatchery. In addition, there are the collections from the Little 

 White Salmon River, from the McKenzie River, and from the lake at Seufert, Oreg. ; 

 but these are not included in this grouping. 



In the following table (45) the data which have been previously presented in sep- 

 arate tables are recombined, so as to show the average lengths, during each month of 

 the year, of the fish captured in each of the four divisions of the river and in the Little 

 White Salmon and McKenzie Rivers. These same data, with the addition of those 

 for the collection from the lake at Seufert, Oreg., are presented in graph i. In the 

 graph, however, the collections from the mouth of the small creek near Point EUice 

 and from the Columbia River near the mouth of Little White Salmon River have 

 been kept separate. 



T.^ble 45. — Average Length op Specimens from the Columbia River for Each Month. 



75412°— 22- 



