55
SUMMARY OF KEY RESULTS TO DATE
Chinook
DFO summer trawl catches were declining and below
the long-term survey average from 2010 to 2014 (Figure 3
top). Since 2016 the CPUE (catch per unit effort) has been
average. In the fall (September/October) surveys have
been variable since 2013 with below average CPUE except
for 2014 and 2018 (Figure 3 bottom).
The CPUE indicates that there are often similar numbers
of juvenile Chinook in the Strait of Georgia in the early
summer and fall. However, DNA analysis indicates that the
Chinook populations present change significantly over the
season. The stock mixture sampled in June is still present in
September, but because South Thompson Chinook enter
the Strait later (primarily July), they are the dominant group
of Chinook (50-70%) captured in September. The reduc-
tion in number of the early ocean entry Chinook stocks
between summer and fall is a combination of mortality
and migration out of the region. However, results from
acoustic tagging studies and the low number of these
stocks captured outside of the Strait of Georgia in late
summer and fall suggests that mortality during the early
marine period in the Strait of Georgia is the primary factor.
In July, the distribution of Chinook Salmon has been very
consistent (Figure 4 top). About 70-80% of Chinook Salmon
are captured near their natal streams.
BQR/Puntledge along ECVI
Cowichan in Gulf Islands
South Thompson in Howe Sound
In September, the distribution of Chinook remains consis-
tent with that seen in July, although there are now far more
South Thompson fish in the SOG (Figure 4 bottom).
Figure 4. Chinook distribution in July (top) and September (bottom).
Figure 3. CPUE ( r) of juvenile Chinook Salmon captured in trawl
surveys 1998-2017. Top figure shows summer CPUE and bottom
figure shows fall CPUE.
Cowichan
BQR/Puntledge
South Thompson
Chilliwack
Harrison
0
20
1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018
SUMMER CPUE
(catch/hr)
40
60
80
100
No
Survey
0
20
1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018
FALL CPUE
(catch/hr)
50
75
100
W.E. Ricker, Canadian research fishery trawler
(retired March 2017)
LEGEND
CHINOOK_2015_14
CPUE/hour
1-10
11-100
101-250
251-500
501-1000
No Catches
LEGEND
CHINOOK_2014_10
CPUE/hour
1-10
11-100
101-250
No Catches
