THE MIGRATION AND CONSERVATION OF SALMON 



higher proportion of one-year smolts than 

 in any other Scottish river. A typical one- 

 year-old Tweed smolt scale was taken from 

 a grilse marked in Norway and recaptured 

 above the tidal waters of the Tweed. A 

 typical two-year-old Tweed parr scale was 

 taken from a fish marked at Loch Inchard 

 and killed later in the Tweed. 



Yet another method of checking roughly 

 the movement of at least the grilse in the 

 Scottish experiments is afforded by the fact 

 that the grilse of the west coast rivers are 

 slightly longer at the end of their first sea 

 year, and slightly longer and heavier at the 

 end of their feeding period, than are the 

 grilse of the east coast rivers. I have taken 

 out these figures for the grilse which were 

 marked on the northwest coast in 1936 and 

 1937: 



These figures show conclusively and con- 

 sistently that the marked fish conformed to 

 the results obtained from fish which have 

 actually returned to, and been caught in, 

 rivers of the two coasts. I should perhaps 

 explain that the considerable difference be- 

 tween the corresponding figures of the two 

 years was due to the fact that the grilse of 

 1936 were exceptionally well grown every- 

 where and were approximately one pound 

 above their average weight. 



Dr. Huntsman. We should define local 

 stocks. From Mr. Menzies' presentation 

 and from previous discussions with Dr. 

 Rich it would seem that there is no point at 

 issue. Dr. Rich stated that he referred 

 not necessarily to anything more than local 

 populations. 



Mr. Menzies. We should get a satisfac- 

 tory name for a local stock in an individual 

 river — I have called them separate biologi- 

 cal races. 



Dr. Huntsman. I believe it desirable 



to have some definite way of indicating 

 that there is no necessary implication of 

 heredity. 



Mr. Menzies. We have two different 

 things — stock in a river and spring fish, 

 summer fish or grilse. 



After discussion of the suitability of 

 "race," "stock" and "population" it was 

 generally agreed that "stock" would be 

 desirable. 



Dr. Huntsman. There will be heredi- 

 tary units. Will it be worth while finding 

 out when and where any such are shown 

 for two generations? 



Mr. Menzies. By hereditary units you 

 mean fish which would return to their 

 native river however you treated them. 



Dr. Belding. Can anyone present fur- 

 nish any evidence of hereditary factors in 

 the different river stocks? 



Mr. Menzies. No. 



Sea Habitat of Salmon 



Dr. Belding introduced this subject, 

 calling attention to the occasional observa- 

 tions of post-smolt salmon. 



Dr. Huntsman. In the Gaspe Basin 

 there have been records where post-smolts 

 have been taken by the fishermen, weighing 

 about three-quarters of a pound. Kendall 

 reports that not infrequently they are taken 

 in traps on the New England coast. 



Mr. Menzies. Is there no possibility of 

 confusing the young salmon with your 

 migratory trout? 



Dr. Belding. No. At all seasons of the 

 year in Massachusetts Bay and on the fish- 

 ing banks, such as Georges, miscellaneous 

 salmon are taken by the trawlers. The 

 records indicate that the salmon are taken 

 within a depth of 70 fathoms. In the old 

 days on Cape Cod traps have taken salmon 

 even in January. These records undoubt- 

 edly constitute a small percentage of the 

 total catch of salmon, since most captures 

 have not been reported. Dr. W. C. Kendall 

 has made a collection of these reports 

 from various sources, such as newspapers, 

 and fishing returns. Evidently scattered 

 salmon are found off the New England coast 

 at all seasons of the year. 



