~ 
MIGRATION OF ADULT SOCKEYE SALMON. 31 
that, in the case of fish which have been recaptured comparatively 
close to the point at which they were liberated, the rate of progress 
is slower than that of fish taken a greater distance from the marking 
station. Also, as may be seen from Table 16, in cases where a retro- 
grade migration has taken place the rate of progress has usually been 
slow. These occurrences may possibly be due to some slight injury, 
or other unfavorable result, due to the handling attendant upon 
tagging. It may also be due to inaccurate data. In either case it 
would seem justifiable, when estimating the normal rate of progress 
through the Sound, to consider only those cases of forward migration 
in which the fish have traveled a reasonably long distance from the 
station at which they were marked, say not less than 20 miles. 
In the case of the Canadian records it will be noted that the corre- 
lation between the distance traveled and the time en route is very 
low. The average time required to pass from station E, at Point 
Roberts, into the Fraser River is 6.7 days. This would indicate a 
much slower rate of migration here than in other parts of the Sound. 
In order to throw additional ight upon this point, the difference 
between the time required for fish marked at stations A, B, C, and D 
to reach the vicinity of Point Roberts (region 9) and that which 
elapsed before the fish from these same stations were taken in Cana- 
dian waters has been calculated as follows: 
Days. 
Vicia ater eg Sas ie a ee Sad ee Ta ol a ae. Nl el aa Med a ae ae 3.3 
SUCH vaya) Byki es | es Se ee a A eS ee ag 
Stalout G2) eee 55 bers Seen eet a eras Heme) Senet ros 3.9 
S Gert OR Sos ie 5 on eee ee ce Ee eg oe 2m bee te 
‘Averaze (simple Mesmmbistt 3-2 ---22)- eso sees ce - 3.47 
This indicates a rate of progress between Point Roberts and the 
Fraser River almost twice as rapid as that indicated solely by the 
results of the marking at Point Roberts, and one agreeing much 
better with the results obtained from the American records. 
The previous tables have shown the rate of travel as the number 
of days required to pass from the marking station to the various 
regions of the Sound. In order to make these figures comparable, 
the rate in miles per day has been calculated for each instance. 
This has been done by simply dividing the distance traveled by the 
time required to make the journey. Table 20 gives the distances 
from each marking station to each of the established regions of the 
Sound. These distances were measured, by means of an ordinary 
map measure, from the marking station to approximately the center 
of the region in question. The most direct route possible was chosen. 
