RAINBOW TROUT 



Salmo gairdnerii . Gibbons 



The rainbow trout, Salmo gairdneriiy was originally distributed along our 

 western coast from southern California to southern Alaska. They have been 

 propagated in hatcheries and planted successfully in most parts of the United 

 States. Much of the rainbows' popularity has been due to the ease with which 

 they adapt themselves to intensive feeding under the crowded conditions found 

 in hatcheries. 



Originally the rainbows were anadromous fish returning to fresh water to 

 spawn. For a time taxonomists differentiated between the sea-run rainbow com- 

 monly called the "steelhead" and the fresh-water form known merely as the 

 rainbow. Now the two variations are recognized as a single species. One of the 

 chief difficulties in starting a population of rainbows in fresh water is their 

 migratory habits which are apparently greater than the brook or brown trout. It 

 has been shown that they do not spawn successfully in lakes but must have suit- 

 able tributaries to spawn in. If they do not find suitable tributaries they will 

 migrate down the inlets where they are lost to the original fishery. Fish screens 

 are hard to maintain and in general very unsatisfactory since the trout would not 

 spawn successfully in the lake anyway. 



The rainbow trout, unlike the other trout, spawn in the spring. Rainbows 

 may spawn from February to June. The rainbow is not as choosy as other trout 

 in picking its spawning tributary, consequently they do not always run spring- 

 fed streams but may follow temporary streams which dry up later resulting in a 

 complete loss of the eggs. Mature females average 1200 eggs per fish. 



The young in hatching remain in the stream for a varying time some of 

 them migrating down to the lake and some, if conditions are acceptable appar- 

 ently stay in the stream throughout their life. The food of the young is insects 

 and crustaceans shifting more to fish as adults. However, insects play an im- 

 portant part in their food throughout life. 



There has been some planting of rainbow trout in Maine but the species is at 

 present rare in the state. They have been reported in the past from Upper Rich- 

 ardson Lake, Oxford County, Kennebago Lake, Franklin County, and Garland 

 Pond, Piscataquis County. Apparently little or no natural reproduction has re- 

 sulted. 



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