Biomass Apportionment Workshop April 29-30, 2009
Introductions Goals of Workshop
Not a decision-making meeting Workshop offers means to evaluate policy, not provide short-term forecasting Outline criteria and basis for evaluation Identify candidate methods and simulate their use Score methods relative to evaluation criteria and if possible identify preferred alternative
April 29-30, 2009 IPHC Biomass Apportionment Workshop 1
Agenda and Process
Background on policy performance evaluation Interactive staff presentations and open discussions. Day 1 Staff presentations
Widget evaluation tool – Juan Valero Performance evaluation and candidate methods – Steven Hare, Ray Webster, and Bruce Leaman Evaluation process – Bruce Leaman
Interactive simulation of dynamics and harvest
Baseline zero harvest scenarios Target harvest rate (i.e. survey apportionment) Historical catch shares Other
Iteration and refinement
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Agenda and Process
Day 2 Review of Day 1 Discussion of alternate scenarios and additional simulations Building the report card Evaluation of alternatives
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Characteristics of Candidate Apportionment Methods
Should address coastwide and area stock management Should have apportionment ‘Sum to 1’, i.e., be consistent across all regulatory areas of the coast Should achieve target harvest rate and provide protection for area-specific spawning contributions Should be sensitive to stock changes, i.e., provide feedback for ongoing apportionment Should be precautionary and robust to uncertainty about stock structure and stock status Note: we have looked at several modifications of the apportionment methods at request of harvesters, although we are not necessarily recommending any of the modifications
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Workshop Output
Reporting of workshop: summary will be drafted and presented to Commission, pertinent results incorporated in fall recommendations. Proceedings, presentations, and output will be posted on IPHC website: www.iphc.washington.edu Proceedings and presentation will be made available on DVD. Reminder that comments on 2010 staff Recommended Catch Limits can be made with Catch Limit Recommendations form by December 31, 2009 via IPHC website. Catch limit recommendations normally posted in first week of December.
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Present state of stock
Recent trajectories of stock condition indices
Generally downward, irrespective of anything to do with apportionment Decreases began about 1999-2000 Decreases, in large part, natural and exacerbated in some areas by previous view of historical biomass distribution Not a result of increases in bycatch mortality
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Recent changes in CPUE
Area 4B
350 300 . . CPUE (lbs/skate) CPUE (lbs/skate) 250 200 150 Commercial 100 50 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 Survey 900 800 700 600 500 400 300 200 100 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 Commercial Survey .
Area 4D
Area 4A
600 500 400 300 200 100 Commercial Survey
Area 3B
700 600 CPUE (lb/skate) 500 400 300 Commercial 200 100 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 Survey CPUE (lb/skate)
Area 3A
600 500 400 300 200 Commercial 100 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 Survey . 450 400 350 CPUE (lbs/skate) 300 250 200 150 100 50 0 1984 1987 1990
CPUE (lbs/skate)
Area 2C
Commercial Survey
1993
1996 YEAR
1999
2002
2005
2008
Area 2B
300 250 200 CPUE (lbs/skate) (lbs/skat. 150 100 50 0 1984 1987 1990 1993 1996 YEAR 1999 2002 2005 2008 Commercial Survey CPUE (lbs/skate) . .
400 350 300 250 200 150 100 50 0 1984 1987 1990
Area 2A
450 Commercial Survey 400 . 350 CPUE (lbs/skate) 300 250 200 150 100 50 0 1993 1996 YEAR 1999 2002 2005 2008 1984 1987
Coastwide
Commercial Survey
1990
1993
1996 YEAR
1999
2002
2005
2008
Bycatch Mortality 1962 - 2008
Bycatch Mortality (Mlbs)
25 20 15 10 5 0 1962 1966 1970 1974 1978 1982 1986 1990 1994 1998 2002 2006
Area 4 Area 3 Area 2
Year
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The age of captured halibut
Survey
Average age in comm. catch
Average age in survey catch
18 17 16 15 14 13 12 11 10 9 4D 4B 4A 3B 3A 2C 2B 2A ALL
Commercial
18 17 16 15 14 13 12 11 10 9 4D 4B 4A 3B 3A 2C 2B 2A ALL
2003 2004 2005 2006 2007
2003 2004 2005 2006 2007
ALL 2A 2B 2C 3A 3B 4A 4B 4D 0% 5% 10% 15%
2003 2004 2005 2006 2007
ALL 2A 2B 2C 3A 3B 4A 4B 4D
2003 2004 2005 2006 2007
20%
0%
5%
10%
15%
20%
25%
Percent older than 20 in survey catch
Percent older than 20 in comm. catch
Percent of Removals 2008
(not including sub-legal bycatch and wastage)
Percent of 2009 Spawning Biomass
3% 5% 15%
7%
2%
13% 13%
2A 2B 2C 3A 3B 4A 4B 4CDE
8% 2% 7%
1%
9% 7%
23% 43%
42%
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4a. Criteria for consideration
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Criteria for consideration
Level of exploitable biomass and spawning biomass Age composition – average age, proportion of older fish, sex ratio Impact of exploitation rate on reproductive value of recruiting fish Proportional contribution of regulatory areas to spawning biomass and removals
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5b. Historic Catch Shares: characteristics and assumptions
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Historic Catch Shares
Simple and straightforward, no modelling involved As an apportionment method catch shares function the same as any other fixed-value approach Unresponsive to stock changes – no penalties (in short term) for errors and no benefits for change in stock status Historic shares contain any embedded errors of contemporary assessments
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Historical total removals
50 45 40
Millions of pounds
2A 2B 2C 3A 3B 4 (all) 4A 4B 4CDE 1950 1970 1990 2010
35 30 25 20 15 10 5 0 1930
Note: Total removals = commercial catch + legal-sized bycatch mortality + sport catch + personal use + wastage
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1 year shares
50% 40% 30% 20% 10% 0% 1990
50% 40% 30% 20% 10% 0% 1990 1995 2000 2005 2010 2A 2B 2C 3A 3B 4A 4B 4CDE
0% 1990 20% 10%
60%
3 year average
2A 2B 2C 3A 3B 4A 4B 4CDE
50% 40% 30% 20% 10% 0% 1990 1995 2000 2005 2010
2A 2B 2C 3A 3B 4A 4B 4CDE
1995
2000
2005
2010
50% 40% 30%
10 year average
15 year average
2A 2B 2C 3A 3B 4A 4B 4CDE 1995 2000 2005 2010
6b. Evaluation process
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Evaluation of Methods
Simulation of impacts using widget Compiling metrics of performance Populating the report card for each method
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Report Card I
State of Nature
RECRUITMENT METHOD A. Survey CA Estimates (1996-2005) Area ALL 4A 3B 3A 2C 2B 2A SB/SB0 HR Survey (1998-2004) SB/SB0 HR Juvenile movement SB/SB0 HR
Control function
B. Alternative
Area ALL 4A 3B 3A 2C 2B 2A
SB/SB0
HR
Yield*
SB/SB0
HR
Yield*
SB/SB0
HR
Yield*
* % change in Yield from Method A
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Report Card II
State of Nature
RECRUITMENT METHOD A. Survey CA Estimates (1996-2005) Area 4A 3B 3A 2C 2B 2A % >20 Avg age Survey (1998-2004) % >20 Avg age Juvenile movement % >20 Avg age
Control function
B. Alternative
Area 4A 3B 3A 2C 2B 2A
% >20 Avg age
% >20 Avg age
% >20 Avg age
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