136 American Fisheries Society 



and their subsequent return to the river. The liberated 

 salmon were marked by metal tags attached by wire to the 

 rear margin of the main dorsal fin. Each tag was stamped 

 with a number which referred to a record of all important 

 facts relative to each fish, so that on recovery of a marked 

 salmon it was possible to follow its history back to the day 

 of its spawning and compare its length, weight, etc., on each 

 occasion. This experiment was carried on for several sea- 

 sons, and in all over 1,200 salmon were marked. Nearly 40 

 of these were recovered with the tags on. A few of them 

 were recovered in the spring following their liberation, and 

 the condition of these fish showed that they had been linger- 

 ing in the river and had taken little or no food. The most 

 of them, however, were retaken during the May and June 

 of the second season following their liberation — that is, two 

 years after their first capture; these salmon had fully re- 

 covered from the emaciation of the spawning season, and 

 measurement showed that in each instance there had been an 

 increase in length. Several of these recaptured fish were 

 females and in the autumn gave a second litter of eggs. Tt 

 is probable that the 40 recaptured fish were only a small 

 portion of the actual survivors out of the 1,200 marked; for 

 it is altogether likely that most of the tags dropped off. In- 

 deed, it seems a wonder that any stayed on, considering the 

 long time that had elapsed and the constant motion to which 

 the tags were subjected, swinging back and forth with every 

 movement of the fish. It being thus established that Atlan- 

 tic salmon return to the river a second time for procreation, 

 being then 6 years old, it is not improbable that a few of 

 them return again, spawning the third time when 8 years old, 

 and quite possible that in rare instances the process may be 

 repeated a fourth time at the age of 10 years. 



It has until recently been supposed that the recovery of 

 a salmon from the exhaustion of the reproductive process 

 required absolutely a return to the sea and a sojourn of 

 some months in its natural element, with access to its natu- 

 ral food, ft was therefore without any expectation of a 



