68 



THE MIGRATION AND CONSERVATION OF SALMON 



errors, he recognized that this difference be- 

 tween the two groups of marked and un- 

 marked adults, 1.34 and 3.2 per cent was of 

 the same order as that of 0.88 and 2.49 per 

 cent given for the 1927 class. He deferred 

 discussion of this discrepancy until other 

 data could be presented. 



In my opinion the .figures are indicative 

 of inwandering of adults from other areas 

 and can not be reconciled with the parent- 

 stream theory. The recovery of 341 marked 

 Cultus Lake sockeye from widely scattered 

 fishing areas, twice as many as reported in 

 the previous experiment, is clearly indicative 

 of the scattering of salmon bred in a 

 particular stream and in part at variance 

 with the parent-stream theory as defined 

 by Foerster (see quotation near the begin- 

 ning of this paper) . 



In 1932 Foerster and Pritchard (1934: 

 82) marked pink salmon fingerlings at Cul- 

 tus Lake. All 8,741 fish marked were liber- 

 ated in the Vedder River and in 1933, 64 

 or 0.73 per cent were taken at various points. 

 The captures showed that pink salmon 

 migrate both north and south around Van- 

 couver Island and no marked fish appeared 

 at Cultus Lake among 800 unmarked which 

 "apparently indicates failure to locate the 

 parent stream." This and other "experi- 

 ments at Masset Inlet seem to indicate that 

 the parent-stream theory may not apply 

 rigidly in the case of the pink salmon." 

 The returns at Masset Inlet indicated a sub- 

 stantial though not complete return to the 

 natal stream. But why do these authors use 

 the word "rigidly" when their figures show 

 not one specimen of marked fish of this spe- 

 cies taken at Cultus Lake, although the 

 entire run there was caught and examined 

 by trained helpers ! 



Wandering Fish 



"While the actual returns of marked fish 

 have been very small in fact, yet the em- 

 phasis has been laid by some investigators 

 on the failure to secure more than trivial 

 instances where such fish have been captured 

 at other streams. This argument appears 

 on analysis to have little weight. The area 



of the field, the number of fishermen and 

 plants involved, the variation in methods 

 of handling the fish captured, the frequent 

 occurrence of other defects in salmon 

 handled, the speed of the cannery processes, 

 and the emphasis laid by canners upon con- 

 stant care for other details make the chances 

 small that any operator will find any partic- 

 ular defect, even if adequate information 

 has been given to all workers in advance. 

 When these and many other variable and 

 unfavorable conditions are considered, the 

 discovery of any wandering marked adults 

 certainly deserves especial emphasis. Since 

 the chances are so small, these few cases 

 carry far more relative weight than the tak- 

 ing of a much larger number in the home 

 stream where everyone is alive to the exact 

 form of the experiment and interested in 

 the outcome. 



The experiments made by marking the 

 fry have been depended on to show that sal- 

 mon return to the stream in which they were 

 hatched. Data on that part of the problem 

 have already been given and discussed. 

 However one feature of the experiment has 

 received scant attention ; that is, the source 

 of the number of unmarked adults returning 

 at the same time. If mentioned at all the 

 figure is usually merely recorded without 

 comment. One exception to this is the report 

 of recent experiments at McClinton Creek, 

 British Columbia. Here Pritchard tabu- 

 lated for three successive cycles of pink sal- 

 mon the number of fry migrants and of 

 returning adults for marked and also for 

 unmarked fish. He states "In every cycle 

 the proportionate return of unmarked fish 

 to McClinton is distinctly larger than that 

 for 'marked'!" The most immediate rea- 

 son for this disparity might be an apparent 

 disadvantage of the maimed young in the 

 struggle for existence. But on the basis of 

 experiments with such marked young held 

 in fresh water for three .months, Pritchard 

 rejects the idea that they are handicapped. 

 Yet after brief discussion of the lack of evi- 

 dence for the basis of this differential mor- 

 tality, he stated that the data available here 

 are inconclusive. 



