Transcript ppt

Charmane Ashbrook, Michael Mizell, & Ken Warheit
Tomelleri
ESA listing
Sport selective fishery impacts?
More reasons
 Variable survival estimates
 Use a control to extricate effects of
handling and tagging
Plan
 Part A, estimate survival
 Part B, estimate encounter rate
Together, these estimates enable us to estimate the impact
of sport selective fisheries on wild steelhead.
Example:
 Yearly escapement --1000 wild fish return
 50% encounter rate --500 captured with sport gear
 95 % survival rate -- 475 lived following release from
sport gear
 5% mortality rate --25 killed by sport gear
Plan
 Part A, estimate immediate and post-release survival
 Part B, estimate encounter rate
Together, these estimates enable us to estimate the impact
of sport selective fisheries on wild steelhead.
Example:
 Yearly escapement --1000 wild fish return
 50% encounter rate --500 captured with sport gear
 95 % survival rate -- 475 lived following release from
sport gear
 5% mortality rate --25 killed by sport gear
Plan
 Part A, estimate immediate and post-release survival
 Part B, estimate encounter rate
Together, these estimates enable us to estimate the impact
of sport selective fisheries on wild steelhead.
Example:
 Yearly escapement --1000 wild fish return
 50% encounter rate --500 captured with sport gear
 95 % survival rate -- 475 lived following release from
sport gear
 5% mortality rate --25 killed by sport gear
Methods
 Capture 30 wild winter steelhead on hook and line
 Capture 30 control fish
 Radio tag –small population, follow movement
 Insert tags surgically, potential iteroparity
 Track fish using fixed and mobile (vehicle) receivers
 Two year study
 Tag fish regardless of wounds, bleeding
 Collect photo, length, scale, DNA, and weight data
 Use GIS to track fish
Methods II
Three parts to survival
1. Immediate : from capture until release
2. Post-release: from release until presumed spawning
3. Out-migration: from presumed spawning until outmigrate from river (kelt)
Pre-season 2009: Little water problem
Results I
Control fish (trap)
2008: 12
2009: 7
Control X fish (previously hooked)
2008: 7
2009: 1
Treatment fish (sport)
2008: 27
2009: 27
Estimating survival
Conceptual example :
Immediate + post-release = total survival
by Keeley, E.R.
Results II --survival
Group
Immediate
survival
Post-release to
presumed
spawning
Survival
Control
100%
100%
Control X
100%
100%
Treatment
100%
100%
Estimating survival--take two
Conceptual example using out-migration
as proxy for spawning:
Immediate + post-release + out-migration = total survival
Results III --survival
Group
Kelted
after
spawning
Sample
size
Survival
relative to
control %
90%
confidence
intervals
2008 Treatment
17
27
75.56
51.2-99.9
2009 Treatment
22
27
95.06
67.0-100.0
----------
----------
85.31
-------------
2008 Control X
5
7
85.71
47.4-100.0
2009 Control X
1
0
0.00
------
2008 Control
10
12
-----
---------
2009 Control
6
7
-----
---------
Average
Treatment
There is a cost to being captured with sport gear.
Results IV--age structure
Age
Number Number
for 2008 for 2009
2.1+
15
21
2.2+
7
4
3.1+
4
0
3.2+
4
0
R.1+
10
5
R.2+
6
0
Notes
One fish had one spawning check (2009)
One fish had one spawning check (2008)
One fish had 2 spawning checks (2008)
Samish steelhead can spawn multiple times but most spawn
only once and after 1 year in saltwater.
Results V --Gender
Year
Group
Lived
Died
Total
2008
Female
22
5
27
2008
Male
11
8
19
2008
Both
33
13
46
2009
Female
13
2
15
2009
Male
15
4
19
2009
Both
28
6
34
2008 more females out-migrated (kelted) than males.
Consistent with other studies and evolutionary theory.
2008 Chi square test p=0.08
2009 Chi square test p=0.56
Results VI--DNA analysis
 2009 group had 5 fish with hatchery parentage
 3 controls and 2 treatment
 3 kelted
 2 with 2.1+ age structure; 2 spawn check
 Feb 23rd to Mar 28th
 2008 group had 8 fish with hatchery parentage
 7 controls and 1 treatment
 7 kelted
 3 with 3+ age structure; 1 spawn check
 Feb 7th to Mar 6th
Comparison with other research
 Evolution of hooking mortality studies, technology
& statistical improvements
 Recent studies
 California, summers, n=126 hook location &
temperature >21C. 1995 & 1996. Fish observed for 36
hours.
 British Columbia, winters, n=226 radio tag. Tag
regurgitation, no control, bleeding fish not included?
Conclusions
 There is a biological cost to sport fishing, 15%
 Relatively high kelting rate may be typical for this kind
of stream, low gradient and near saltwater
 Fair % of “wild” fish had hatchery influence
 Despite high kelting rate, relatively few fish were >
first time spawners based on scale analysis
Further explorations
 Evaluate in higher gradient, further in-river system;
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fish that must travel further may have a lower
survival
In estuary environment survival will likely be lower
Estimate recapture survival
Kelt migration and movement patterns in saltwater
Consider if management objective to separate
hatchery and wild fish based on return timing is
successful
Summer steelhead survival may be lower because of
warmer water and longer time in freshwater
Estimate encounter rate to estimate impact to
population
Acknowledgements
 Samish Hatchery Crew
 Bob Leland & Steve Schroder
 Equipment: USGS, University of Idaho, & Pete Hahn
 Technicians: Jen Mertes, Ryan Regner, Jim Crook,
Faith Sandretzky, and Kyle Gulbranson
 Earl Steele and his fisheries class at Bellingham
Technical College; Jim Naranovich
 Fishermen: Brett Barkdull, Curt Kraemer, and local
volunteers
Hook location
Treatment (sport caught)
34 maxillary
1 behind eye
3 snout
1 top of head
1 no data
Control X (hatchery weir, previously hooked)
6 maxillary
1 no data
Fishing gear
Artificial bait
Corky
Eggs
Float
Sand shrimp
Yarn
Gender
2008
Group
Control
Treatment
Hooked
Control
Female
8
15
4
Male
4
12
3
Unknown
0
0
0
Both
12
27
7
2009
Group
Control
Treatment
Hooked
Control
Female
4
13
0
Male
3
13
1
Unknown
0
1
0
Both
7
27
1