questions about marine- derived nutrients and c&r fisheries to be answered in the discussion hal...
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QUESTIONS ABOUT MARINE-DERIVED NUTRIENTS AND C&R FISHERIES TO BE ANSWERED IN
THE DISCUSSION
Hal Michael Washington Department of Fish and Wildlife
QUESTIONS TO KEEP IN MIND
• How can sufficient amount of MDN be delivered to a stream?
• How can the differential effect of MDN on smolt age and productivity be modeled?
Effect of nutrient addition on Keogh steelhead smolt ages
0%20%40%
60%80%100%
age 4
age 3
age 2
age 1
Soos Creek Steelhead IIREMOVE LOW FLOW YEARS
SH esc-3 yr shift
0
100
200
300
400
500
600
700
0.000 0.010 0.020 0.030 0.040 0.050 0.060 0.070 0.080 0.090 0.100
Flow adjusted coho spawner biomass density
Ste
elh
ea
d s
pa
wn
ers
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
EF-1* EF-2* EF3
Location
De
ns
ity
wiig
hte
d p
erc
en
t in
cre
as
e in
len
gth
SH-0
SH-1
COHO
SALMON CREEK INCREASE IN LENGTH
SNOW CREEK INCREASE IN LENGTH
0.0
10.0
20.0
30.0
40.0
50.0
60.0
EF-1* EF-2 EF-3 EF-4 EF-5
Location
De
ns
ity
we
igh
ted
me
an
inc
rea
se
in le
ng
thSH-0
SH-1
COHO
Comparison of various carcass biomass loading rates and 1998-2002 carcass loadings for the Skagit River.
Loadings in kg/m²
Watershed % provided
Load Justification need min esc max esc reference
0.07 no growth increase 1,477,000 30.5% 159.8% Claeson (MS thesis.)
0.15 coho to coho 3,165,000 14.2% 74.6% Bilby et al. (2001)
0.63 enhance Keogh 13,300,000 3.4% 17.8% Ashley and Slaney (1997)
0.78 sockeye to insects 16,500,000 2.7% 14.3% Bilby et al. (2001)
1.9 system capacity 40,100,000 1.1% 5.9% Wipfli et al. (2003)
Coho
Sp Chin F Chin Chum TOTAL “ECOSYSTEM”
GOAL-GRAYS HARBOR 634,342 66,314 761,577 12,692,956
TOTAL AT "NO EFFECTS" LEVEL OF LOADING 296,026 30,946 88,851 177,701
AVERAGE ESCAPEMENT 2001-2006 66,777 2,834 18,106 26,670
% OF "NO EFFECTS" LOAD 22.56% 9.16% 20.38% 15.01%
MDN NUTRIENT RELATIONSHIPS WITH STEELHEAD
• Increased MDN lowers smolt age
• Lower smolt age gives higher smolt capacity for stream and productivity per female
• Nutrients must be delivered to the parts of the system where there are rearing steelhead
CATCH AND RELEASE CONCERNS
• Does a C&R fish spawn in the same location, same fecundity, same survival to emergence, and same survival to repeat spawning as an uncaught fish?
• What is the effect of being caught multiple times?
• When is a fishery “too close” to spawning time?
• Is C&R of kelts harmful?