B. Witch Flounder Summary of
Summary of B. Witch Flounder SAW/SARC 62 Data Meeting September 13-16, 2016 Model Meeting October 4-7, 2016 Working Group Members Liz Brooks Doug Butterworth Jamie Cournane Mike Palmer Mark Terceiro, Chair Harvey Walsh Susan Wigley, Lead
Summary of B. Witch Flounder SAW/SARC 62 SARC Review November 29 to December 2, 2016 Patrick J. Sullivan (Chair) Vivian Haist Neil Klaer Anders Nielsen
SARC 62 Summary • Status: Unknown and Unknown • Age structured models should not be use due to the major retro. • Empirical area swept method suggests the biomass has declined over time. • Age truncation is evident in both the landings and surveys. • Empirical area swept method provides a 2017 OFL of 728 mt based on a relative exploitation rate of 0.05 (avg rate 2008-2015, range 0.03-0.07).
Slow growing, long-lived, late maturing, exhibiting sexual dimorphism NEFSC survey: 73 cm max length (24 yrs); 30 yrs max age (64 cm) Commercial landings: 70 cm max length (14 yrs); 33 yrs max age ( 61 cm)
Figure B13 7000 6000
USA Landings
Metric tons
5000 4000 3000 2000 1000
Discards
0 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Year Figure B13. USA witch flounder landings (mt), excluding USA landings from the Grand Banks in the mid-1980's. The thin line represents provisional landings data taken from Lange and Lux (1978). Discards are from the Gulf of Maine shrimp trawl, scallop dredge, gillnet, haddock separator trawl, small-mesh (5.5 inch) otter trawl fisheries.
Figure B14
Percentage of landings by statistical areas 100%
90%
80%
522 6 54
70%
53 60%
521
524
562
523
561
526 525 50%
515 40%
522 521 515 514 513
30%
514
0%
511 465 464
20%
10%
512
513
Percentage of landings by market category
Large
Medium
Small PeeWee
Smalls: 33 – ~48 cm Mediums: ~43 – ~53 cm Larges: ~48 – ~58 cm
ages 4 -10 ages 8 -11+ ages 9 -11+
Figure B17
1982-2015 Qtr 1
1982-2015 Qtr 2
1982-2015 Qtr 3
1982-2015 Qtr 4
provided by C Tholke
Figure B21
Bigelow used from 2009 onward
provided by A Miller
Landings At Age
Figure B28
Commercial Landings at Age 1982
• Commercial port samples taken by market category and quarter;
1984 1986 1988 1990
• LF and age samples summarized in Table B15;
• Ages 6 to 9 majority (CVs generally < 15%) • Truncated age structure
1994 1996
Year
• Annual sampling ranged from 11 to 113 mt per 100 lengths, exceeding the informal sampling threshold of 200 mt per 100 lengths.
1992
1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
4
5
Age
6
7
8
9
10
11 +
Total Discards At Age
Figure B30
1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
4
5
Age
6
7
8
9
10
11+
Total Catch At Age
Figure B31
1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
WG accepted the catch at age as derived
4
5
6
Age
7
8
9
10
11+
Figures B34, B35 NEFSC strata 22-30, 36-40
NEFSC SPRING
Figure B41
NEFSC FALL
Figure B42
Recent values are below time series means. 4.0
3.0
2.0
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
1975
1972
1969
2014
6
2014
5.0
2011
Fall Biomass (kg/tow)
2011
2008
2005
2002
0.0
1999
0
1996
1.0
1993
2
1990
4
1987
6.0
1984
7.0
1981
8 7
1978
10 8
1975
Fall Abundance (numbers/tow) 1966
4
1963
2014
2011
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
6
1972
0
1975
8
1969
0
1972
10
1966
1
1969
Spring Abundance (numbers/tow)
1963
2014
2011
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
12
1975
2
1966
12
1972
1963
14
1969
1966
1963
NEFSC Survey (strata set 22-30, 36-40) Figure B44
Spring Biomass (kg/tow)
6
5
4
3
2
NEFSC
Spring Survey: Stratified mean number per tow at age
1980 1982 1984 1986 1988 1990 1992
Year
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 0
1
2013 year class
2
3
4
5
6
7 8 Age
9
10
11
12
13
14 +
Figure B48
NEFSC
Autumn Survey: Stratified mean number per tow at age
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 0
1
2
3
4
5
6
7
Age
2013 year class
8
9
10
11
12
13
14 +
Figure B48
ASMFC Shrimp Summer Survey WG: Although this survey has limited spatial coverage, much of the juvenile range is covered. This survey appears to provide useful information on relative to trends in abundance, distribution and recruitment of witch flounder in the Gulf of Maine and could be considered as tuning indices. Strata set used: 1, 3, 6, and 8
Figure B61
Stratified mean weight (Kg) per tow
ASMFC Shrimp Survey
11
Figure B64
10 9 8 7 6 5 4 3 2 1 0 1984
1988
1992
1996
2000
2004
2008
2012
2016
2004
2008
2012
2016
Year Stratified mean number per tow
160 140 120 100 80 60 40
#/tow
20 0 1984
1988
1992
1996
2000
Year
ASFMC Shrimp Survey
Figure B66
1980 1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002
Age structures not collected on this survey;
2004 2006 2008
Applied NEFSC spring and fall (combined) ALK
2010 2012 2014
2013 year class
0
1
2
3
4
5
6
7 8 Age
9
10
11 + 12
13
14
ME-NH Inshore Survey WG: Although this survey has limited spatial coverage, much of the juvenile range is covered. This survey appears to provide useful information on relative to trends in abundance, distribution and recruitment of witch flounder in the Gulf of Maine and could be considered as tuning indices.
Figure B69
Figure B76
ME-NH Survey
2013 yc
Figure B79
MENH survey with NEFSC spring and fall ALKs applied
2013 year class
Figure B94
Note: NEFSC survey includes young fish than Dealer landings data so peaks and valleys do not always align.
Empirical Estimates of Maximum Catchability of Witch Flounder on the Northeast Fisheries Science Center Fall Bottom Trawl Survey Northeast Fisheries Science Center
Jon Hare, John Hoey, John Manderson, Michael Martin, Phil Politis, David Richardson, and Chris Roebuck
01/13/2017
Rock-hopper
Chain sweep
Empirical Area Swept Approach Steps: • • • • • • • • •
Start with NEFSC surveys catch per tow (kg/tow) Convert Bigelow to Albatross Calculate minimum swept area biomass Estimate population B assuming BIG catchability = 1 Estimate population B assuming chain sweep q = 1 Average Fall and Spring surveys to get population B Convert survey population B to exploitable B Apply exploitation rate to create OFL Apply scientific uncertainty to create ABC
Figure B113
Combine Fall and Spring Fall (year t) and Spring (year t+1)
• Allows use of most recent survey information • Estimates start of year biomass
86% decline in Pop B (5 yr avg 1967-1971 to 5 yr avg 2011-2015)
Figure B116
Historical Exploitation Rates • Actual catch (year t) divided by avg B (years t-1 Fall and t Spring) • Shows exploitation rate of 0.23 (F40% = 0.28) higher than all but one historic exploitation rates for this scenario • One way to “ground truth” choice of exploitation rate • Magnitude, but not trend, will change as choices for q, area, conversions, etc. change
0.25
0.05
Avg B to Catch Advice
Figure B117
Table B55 clip 0.9
…
catch advice year 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
avg mt 93899 109188 155567 102164 124414 154057 101332 77301 84458 51734 106117 84370 98487 108636 72481 63770 67464 90821 52512 30998
0.05
0.75
exploitable biomass (mt) Est. OFL (mt) . ABC (mt) 84509 4225 3169 98269 4913 3685 140011 7001 5250 91948 4597 3448 111973 5599 4199 138651 6933 5199 91199 4560 3420 69571 3479 2609 76012 3801 2850 46560 2328 1746 95505 4775 3581 75933 3797 2848 88638 4432 3324 97772 4889 3666 65232 3262 2446 57393 2870 2152 60717 3036 2277 81739 4087 3065 47261 2363 1772 27898 1395 1046
• Avg B (Fall year t, Spring year t+1) provides catch advice for year t+2 • Exploitable B multiplier of 0.9 based on comparing fishery and survey catch at age • Exploitation rate of 0.05 based on mean of most recent nine years given trends in survey and estimated catches. • ABC = 0.75 * OFL based on common practice
Uncertainties • • • • • • • • •
BIG:ALB calibration Area of survey Tow footprint (wing and door spread) Chainsweep:rockhopper calibration Survey avg B:exploitable B conversion Exploitation rate to apply for catch advice Reference points Cannot project, ignores age information To smooth or not to smooth
Within the empirical approach Survey trends do not change, only magnitude changes.
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“The witch flounder age-structured assessment model, while scientifically well thought out, had major retrospective patterns in the estimates. Those model results are not recommended for management purposes. The status of the witch flounder stock is currently unknown relative to biological reference points. The panel believes that the previously accepted VPA model is not an acceptable alternative to the rejected ASAP application because it exhibits a similar major retrospective pattern.”
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“An empirical swept area approach may be useful for setting catch advice, although the Panel did not have time to fully review it in the context of the ToR of the meeting. As an FMSY proxy, the Panel supports using a relative exploitation rate derived from the average exploitation (recent catch divided by recent swept area exploitable biomass estimates) in the near term, where other alternatives are unavailable.”
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“The spring and autumn NEFSC surveys are regarded as providing the best available fishery independent indices for this species and they show broadly similar patterns of a decline from the early 1960s to record low levels in the late 1980s and early 1990s, an increase to early 2000s followed by a declining trend. The empirical area swept method does not provide a biomass threshold, but does indicate that the stock is at low historical levels.”
Questions?
From 2016 Scallop Habcam
Summary of B. Witch Flounder SAW/SARC 62 SARC Review November 29 to December 2, 2016 Patrick J. Sullivan (Chair) Vivian Haist Neil Klaer Anders Nielsen
SARC 62 Summary • Status: Unknown and Unknown • Age structured models should not be use due to the major retro. • Empirical area swept method suggests the biomass has declined over time. • Age truncation is evident in both the landings and surveys. • Empirical area swept method provides a 2017 OFL of 728 mt based on a relative exploitation rate of 0.05 (avg rate 2008-2015, range 0.03-0.07).
Slow growing, long-lived, late maturing, exhibiting sexual dimorphism NEFSC survey: 73 cm max length (24 yrs); 30 yrs max age (64 cm) Commercial landings: 70 cm max length (14 yrs); 33 yrs max age ( 61 cm)
Figure B13 7000 6000
USA Landings
Metric tons
5000 4000 3000 2000 1000
Discards
0 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Year Figure B13. USA witch flounder landings (mt), excluding USA landings from the Grand Banks in the mid-1980's. The thin line represents provisional landings data taken from Lange and Lux (1978). Discards are from the Gulf of Maine shrimp trawl, scallop dredge, gillnet, haddock separator trawl, small-mesh (5.5 inch) otter trawl fisheries.
Figure B14
Percentage of landings by statistical areas 100%
90%
80%
522 6 54
70%
53 60%
521
524
562
523
561
526 525 50%
515 40%
522 521 515 514 513
30%
514
0%
511 465 464
20%
10%
512
513
Percentage of landings by market category
Large
Medium
Small PeeWee
Smalls: 33 – ~48 cm Mediums: ~43 – ~53 cm Larges: ~48 – ~58 cm
ages 4 -10 ages 8 -11+ ages 9 -11+
Figure B17
1982-2015 Qtr 1
1982-2015 Qtr 2
1982-2015 Qtr 3
1982-2015 Qtr 4
provided by C Tholke
Figure B21
Bigelow used from 2009 onward
provided by A Miller
Landings At Age
Figure B28
Commercial Landings at Age 1982
• Commercial port samples taken by market category and quarter;
1984 1986 1988 1990
• LF and age samples summarized in Table B15;
• Ages 6 to 9 majority (CVs generally < 15%) • Truncated age structure
1994 1996
Year
• Annual sampling ranged from 11 to 113 mt per 100 lengths, exceeding the informal sampling threshold of 200 mt per 100 lengths.
1992
1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
4
5
Age
6
7
8
9
10
11 +
Total Discards At Age
Figure B30
1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
4
5
Age
6
7
8
9
10
11+
Total Catch At Age
Figure B31
1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
0
1
2
3
WG accepted the catch at age as derived
4
5
6
Age
7
8
9
10
11+
Figures B34, B35 NEFSC strata 22-30, 36-40
NEFSC SPRING
Figure B41
NEFSC FALL
Figure B42
Recent values are below time series means. 4.0
3.0
2.0
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
1975
1972
1969
2014
6
2014
5.0
2011
Fall Biomass (kg/tow)
2011
2008
2005
2002
0.0
1999
0
1996
1.0
1993
2
1990
4
1987
6.0
1984
7.0
1981
8 7
1978
10 8
1975
Fall Abundance (numbers/tow) 1966
4
1963
2014
2011
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
6
1972
0
1975
8
1969
0
1972
10
1966
1
1969
Spring Abundance (numbers/tow)
1963
2014
2011
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
12
1975
2
1966
12
1972
1963
14
1969
1966
1963
NEFSC Survey (strata set 22-30, 36-40) Figure B44
Spring Biomass (kg/tow)
6
5
4
3
2
NEFSC
Spring Survey: Stratified mean number per tow at age
1980 1982 1984 1986 1988 1990 1992
Year
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 0
1
2013 year class
2
3
4
5
6
7 8 Age
9
10
11
12
13
14 +
Figure B48
NEFSC
Autumn Survey: Stratified mean number per tow at age
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 0
1
2
3
4
5
6
7
Age
2013 year class
8
9
10
11
12
13
14 +
Figure B48
ASMFC Shrimp Summer Survey WG: Although this survey has limited spatial coverage, much of the juvenile range is covered. This survey appears to provide useful information on relative to trends in abundance, distribution and recruitment of witch flounder in the Gulf of Maine and could be considered as tuning indices. Strata set used: 1, 3, 6, and 8
Figure B61
Stratified mean weight (Kg) per tow
ASMFC Shrimp Survey
11
Figure B64
10 9 8 7 6 5 4 3 2 1 0 1984
1988
1992
1996
2000
2004
2008
2012
2016
2004
2008
2012
2016
Year Stratified mean number per tow
160 140 120 100 80 60 40
#/tow
20 0 1984
1988
1992
1996
2000
Year
ASFMC Shrimp Survey
Figure B66
1980 1982 1984 1986 1988 1990 1992 1994
Year
1996 1998 2000 2002
Age structures not collected on this survey;
2004 2006 2008
Applied NEFSC spring and fall (combined) ALK
2010 2012 2014
2013 year class
0
1
2
3
4
5
6
7 8 Age
9
10
11 + 12
13
14
ME-NH Inshore Survey WG: Although this survey has limited spatial coverage, much of the juvenile range is covered. This survey appears to provide useful information on relative to trends in abundance, distribution and recruitment of witch flounder in the Gulf of Maine and could be considered as tuning indices.
Figure B69
Figure B76
ME-NH Survey
2013 yc
Figure B79
MENH survey with NEFSC spring and fall ALKs applied
2013 year class
Figure B94
Note: NEFSC survey includes young fish than Dealer landings data so peaks and valleys do not always align.
Empirical Estimates of Maximum Catchability of Witch Flounder on the Northeast Fisheries Science Center Fall Bottom Trawl Survey Northeast Fisheries Science Center
Jon Hare, John Hoey, John Manderson, Michael Martin, Phil Politis, David Richardson, and Chris Roebuck
01/13/2017
Rock-hopper
Chain sweep
Empirical Area Swept Approach Steps: • • • • • • • • •
Start with NEFSC surveys catch per tow (kg/tow) Convert Bigelow to Albatross Calculate minimum swept area biomass Estimate population B assuming BIG catchability = 1 Estimate population B assuming chain sweep q = 1 Average Fall and Spring surveys to get population B Convert survey population B to exploitable B Apply exploitation rate to create OFL Apply scientific uncertainty to create ABC
Figure B113
Combine Fall and Spring Fall (year t) and Spring (year t+1)
• Allows use of most recent survey information • Estimates start of year biomass
86% decline in Pop B (5 yr avg 1967-1971 to 5 yr avg 2011-2015)
Figure B116
Historical Exploitation Rates • Actual catch (year t) divided by avg B (years t-1 Fall and t Spring) • Shows exploitation rate of 0.23 (F40% = 0.28) higher than all but one historic exploitation rates for this scenario • One way to “ground truth” choice of exploitation rate • Magnitude, but not trend, will change as choices for q, area, conversions, etc. change
0.25
0.05
Avg B to Catch Advice
Figure B117
Table B55 clip 0.9
…
catch advice year 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
avg mt 93899 109188 155567 102164 124414 154057 101332 77301 84458 51734 106117 84370 98487 108636 72481 63770 67464 90821 52512 30998
0.05
0.75
exploitable biomass (mt) Est. OFL (mt) . ABC (mt) 84509 4225 3169 98269 4913 3685 140011 7001 5250 91948 4597 3448 111973 5599 4199 138651 6933 5199 91199 4560 3420 69571 3479 2609 76012 3801 2850 46560 2328 1746 95505 4775 3581 75933 3797 2848 88638 4432 3324 97772 4889 3666 65232 3262 2446 57393 2870 2152 60717 3036 2277 81739 4087 3065 47261 2363 1772 27898 1395 1046
• Avg B (Fall year t, Spring year t+1) provides catch advice for year t+2 • Exploitable B multiplier of 0.9 based on comparing fishery and survey catch at age • Exploitation rate of 0.05 based on mean of most recent nine years given trends in survey and estimated catches. • ABC = 0.75 * OFL based on common practice
Uncertainties • • • • • • • • •
BIG:ALB calibration Area of survey Tow footprint (wing and door spread) Chainsweep:rockhopper calibration Survey avg B:exploitable B conversion Exploitation rate to apply for catch advice Reference points Cannot project, ignores age information To smooth or not to smooth
Within the empirical approach Survey trends do not change, only magnitude changes.
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“The witch flounder age-structured assessment model, while scientifically well thought out, had major retrospective patterns in the estimates. Those model results are not recommended for management purposes. The status of the witch flounder stock is currently unknown relative to biological reference points. The panel believes that the previously accepted VPA model is not an acceptable alternative to the rejected ASAP application because it exhibits a similar major retrospective pattern.”
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“An empirical swept area approach may be useful for setting catch advice, although the Panel did not have time to fully review it in the context of the ToR of the meeting. As an FMSY proxy, the Panel supports using a relative exploitation rate derived from the average exploitation (recent catch divided by recent swept area exploitable biomass estimates) in the near term, where other alternatives are unavailable.”
SARC 62 Meeting Outcome (page 2 of assessment summary report)
“The spring and autumn NEFSC surveys are regarded as providing the best available fishery independent indices for this species and they show broadly similar patterns of a decline from the early 1960s to record low levels in the late 1980s and early 1990s, an increase to early 2000s followed by a declining trend. The empirical area swept method does not provide a biomass threshold, but does indicate that the stock is at low historical levels.”
Questions?
From 2016 Scallop Habcam
