488 Memoir Sears Foundation for Marine Research 



gouche Salmon clubs and of New Brunswick and Quebec fishery statistics {^^d). Phelps 

 and Belding corroborated Griswold's findings from the records of the Restigouche 

 Club, noting a periodicity of nine or ten years extending back to 1879 {114). Hunts- 

 man used for his study the fishery statistics of the Maritime Provinces of Canada, which 

 extended back to 1869 (55: 9—14). Huntsman attributed periodicity in Atlantic Salmon 

 to periodicity in rainfall {6o\ 17—28; 72: 43—53)- Griswold related it to a nine-year 

 cycle of tides, believing that coastal currents move offshore and onshore in cycles 

 of nine years. Phelps and Belding believed that an oceanic — or possibly a river — 

 condition affected the migrating smolts periodically. What connection, it any, there 

 may be between such periodicity and the nine- or ten-year periodicity in terrestrial 

 animals such as the varying hare {Lepus americanus), ruffed grouse {Bonasa umbellus), 

 and some others is not known {40: 1—34). 



Atlantic Salmon catches in Great Britain and Ireland also fluctuate and show a 

 striking similarity to those in America {88). Svardson, while noting a tendency toward 

 parallel trends in the yields of Atlantic Salmon fisheries in Great Britain, Norway, 

 Sweden, and Holland, has pointed out that they are not parallel every year {124: 226— 

 262). He believes that he found a statistically significant positive correlation between 

 the area of ice cover in the Baltic and the Atlantic Salmon catch five years later, sug- 

 gesting, in explanation, that severe winters cause the death of large numbers of the 

 common porpoise, which preys on them. Lindroth, however, questioned Svardson's 

 conclusions, arguing that the short-term fluctuation is only an artifact created by the 

 long-term fluctuation, which is dependent on climate (9^). 



Maintenance and Restoration of the Fishery. The problem of maintaining or re- 

 storing the species is largely one of assuring that conditions necessary for successful 

 spawning, hatching, survival, and growth in fresh water are maintained or restored. 

 There are no reasons for believing that the sea could not support as large populations 

 today as it did hundreds of years ago; therefore it is in the rivers that remedial action 

 is necessary. 



Salmon thrive best under the primitive conditions of northern regions. They 

 require cold water and, for reproduction, clean gravel. The changes incidental to settle- 

 ment and industrial development that destroy these conditions have already been 

 mentioned under Decline in Abundance. The problem of preserving Salmon is that of 

 halting these injurious forces and, when possible, of restoring favorable conditions. 

 The failure of experiments to reintroduce Atlantic Salmon into a stream flowing into 

 Lake Ontario where they formerly spawned illustrates the detrimental effects of man's 

 activities {g8). Apart from mill dams that formerly barred the fish from reaching the 

 spawning grounds, the changes brought about in the conditions of this stream were 

 due to lumbering, which removed the tree cover, and to farming, which exposed the 

 soil to erosion. High lethal temperatures eliminated the planted fry from some sections, 

 and over the balance of the planted part, the greatest mortality occurred soon after 

 planting when heavy predation by other species of fish occurred. The extent of preda- 

 tion was related largely to the amount of suitable shelter for the fry. This was limited 



