Post on 17-Dec-2015
Black Sea Bass – Northern Stock
Coastal-Pelagic/ASMFC Working Group Review
June 15, 2010
Update of assessment approach adopted by the Data Poor Stocks Working Group ( Dec 2008) and the 2009 assessment (June 2009).
Approach:
Length-based model of population parameters
- require time series of catch, survey indices
Compare results to biological reference points to determine stock status
Produce projections based on model results
Life History –
Distributed Maine through Gulf of Mexico
Managed as single stock north of Cape Hatteras
Protogynous hermaphrodite: Transition to male at age 2-5
Seasonal migrations inshore/offshore
Maximum age 15 (?)
50% mature 21 cm
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Length (cm)
Pro
port
ion
Mat
ure
Black sea bass size at maturity from NEFSC spring surveys
Black Sea Bass size limits
8
9
10
11
12
13
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007Year
Min
imu
m s
ize
(in
ches
)
Commercial
Recreational
Commerical Landings
0
2
4
6
8
10
1219
39
1942
1945
1948
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
Year
MT
(000
s)
28.8%
17.2%37.6%
8.3%
0.2%
8.0%
29.8%
21.5%
31.9%
7.8%0.3%
8.7%
large
jumbo
medium
small
ex small
unclassified
2008 and 2009 commercial black sea bass landings
Values in blue - estimates from commercial ratio
Recreational Landings
0
1
2
3
4
5
6
Year
MT
(000
s)
Recreational Discard weight
Discard weight estimated using landing mean weight
Recreational Discards
0
100
200
300
400
500
600
700
800
900
Year
MT
(00s
)
OT from observer 1989-2008
Pot and handline from VTR 1994-2008
2009 estimate from series average
Commercial Discards
0
50
100
150
200
250
300
350
400
450
500
Year
MT
Black sea bass catch estimates
Rec discard mortality = 25% Com discard mortality = 25-50%
0
1
2
3
4
5
6
7
8
9
Year
MT
(000
s)
com disc
rec disc
rec landed
com landed
43%
39%
14%
4%
Commercial landings
recreational landing
rec discard losses
com discard losses
2005-2009 average sea bass catch components
1990
0
100
200
300
400
500
600
700
800
900
1000
Length (cm)
Fre
quen
cy (
000s
)1985
0
100
200
300
400
500
600
700
800
9001 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
qu
ency
(00
0s)
1995
0
100
200
300
400
500
600
700
800
900
1000
Length (cm)
Freq
uenc
y (0
00s)
2000
0
100
200
300
400
500
600
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
quen
cy (0
00s)
Combined Recreational/Commercial landings length frequency
1985
1990
1995
2000
2001
0
100
200
300
400
500
600
700
Length (cm)
Freq
uenc
y (0
00s)
2002
0
100
200
300
400
500
600
700
800
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
quen
cy (0
00s)
2003
0
100
200
300
400
500
600
700
1 4 7 10
13
16
19
22
25
28
31
34
37
40
43
46
49
52
55
58
61
64
Length (cm)
Fre
qu
ency
(0
00
s)
2004
0
50
100
150
200
250
300
350
400
450
500
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
qu
ency
(00
0s)
Combined Recreational/Commercial landings length frequency
2001
2002
2003
2004
2005
0
50
100
150
200
250
300
350
4001 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
quen
cy (
000s
)
2006
0
50
100
150
200
250
300
350
400
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Fre
quen
cy (0
00s)
2007
0
50
100
150
200
250
300
350
400
450
500
Length (cm)
Freq
uenc
y (0
00s)
Combined Recreational/Commercial landings length frequency
2005
2006
2007
2008
0
50
100
150
200
250
300
350
400
Length (cm)
Freq
uenc
y (0
00s)
2008
2009
0
50000
100000
150000
200000
250000
300000
3500001 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Length (cm)
Freq
uenc
y
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
36.0
Year
Leng
th (c
m)
Mean and Median length of sea bass landings
median
mean
Northeast Fisheries Science Center Trawl Survey
Spring offshore strata 1968 – 2009 (Bigelow conversion coefficient = 3.416)
Winter offshore strata 1992 – 2007
Loge transform indices
NEFSC Indices of sea bass adult abundance (>22 cm)
(stratified mean #/tow)
1.0
2.0
3.0
4.0
5.0
6.0
7.0
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Mea
n #
/tow
spring offshore
winter offshore
NEFSC Spring and Winter indices of juvenile abundance (stratified mean #/tow)
0.000.100.200.300.400.500.600.700.800.901.00
Year
Mea
n #/
tow
-spr
ing
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Mea
n #/
tow
-win
ter
SCALE model
SCALE model (P. Nitschke NMFS,NEFSC)
Length based catch at age model
Inputs : NEFSC spring (1968-2009) and winter surveys (1992-2007)
adult (> 22 cm) and recruitment (< 14 cm)
Survey length frequencies (1968-2009,1992-2007)
Fishery catch series (1968-2009)
Fishery length frequencies (1984-2009)
Selectivity periods (1984-1997, 1998-2000, 2001-2009)
Mean length at age and std. deviations
Length-weight equation (from survey series)
Natural mortality estimate (0.4)
Sea Bass growth used in SCALE
Mean length + 2 stdev
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12
Age
Leng
th (c
m)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Length (cm)
Sele
ctiv
ity
1968-1997
1998-2000
2001-2008
Selectivity used in the SCALE model
Model results influenced by presence of juvenile indices, weighting factors, etc.
Which is correct model?
Adopted model averaging approach (Burnham and Anderson (2002)
Scale modeling approach:
Run Number 1 2 3 4 7 8 9 10 11 12
Total Objective Function 266.6 261.4 297.3 291.7 269.0 256.1 257.1 252.5 263.3 266.6
Weight on Catch Weight 15 15 15 15 20 20 25 25 25 25
Weight on Recruitment Index 1: spring 15 15 15 15 15 15 15 15 15 20
Winter 2007 juvenile index x x x x x x x
Weight on Recruitment Index 2: winter 15 15 15 15 15 15 15 15 10 10
Autumn juvenile index series included x x
Weight on Recruitment Index 3: fall 15 15
Weight for Adult Index 1: spring ln 15 15 15 15 15 10 10 10 15 15
Weight for Adult Index 2: winter ln 15 15 15 15 15 10 10 10 15 15
Observed and estimated average (+ 2 std dev) black sea bass catch
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Cat
ch (
mt)
NMFS Spring index – predicted vs observed (index +1)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.819
68
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Mea
n #
/tow
predicted
observed
NMFS Winter index – predicted vs observed (index +1)
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Mea
n #
/tow predicted
observed
Wt’d Average Fishing mortality + 2 std dev from SCALE model estimates
Fmsy
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Fis
hin
g M
orta
lity
Wt’d Average Recruitment + 2 std dev from SCALE model estimates
Recruitment (age 1)
0
10000
20000
30000
40000
50000
60000
70000
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Abu
nda
nce
(000
s)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
year
Bio
mas
s (m
t)Wt’d Average Total Biomass + 2 std dev from SCALE model estimates
Bmsy
Wt’d Average Total Abundance + 2 std dev from SCALE model estimates
-
20,000
40,000
60,000
80,000
100,000
120,000
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Year
Ab
un
dan
ce (
000s
)
Wt’d Average Spawning Stock Biomass + 95% CI from SCALE model estimates
-
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
year
SS
B (
mt)
SSBmsy
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
SSB (000s mt)
Fis
hing
Mor
talit
y
SSBmsy/2 = 6,269 mt
Fmsy = F40%= 0.42
SSBmsy =12,537 mt
2009
Relationship between SSB and F
Projection approach
Use predicted output as new input. Input F for projections and allow model to predict catch.
Survey data in 2009 and 2010 treated as missing.
2010 Catch assumed equal to quota plus average discard.
2010-2012 lf 5 year average
Average spring and winter indices
Average recruitment variation, starting recruitment and starting F
Ref pts
MSY 3,903
SSBmsy 12,537
Bmsy 13,977
Fmsy 0.42
Projection if F2010 = F2008
F Landings (mt) Discards (mt) SSB (mt)
F2011=Fmsy 0.42 2,772 693 13,872
F2011 = 75% Fmsy 0.32 2,166 542 14,636
F2011=F2009 0.29 1,974 493 14,677
Quota=status quo 0.23 1,633 408 15,335 (catch = 4.5 million lbs)
Retrospective patterns in typical model run
run 7 Fishing mortality
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
year
F
run 7 Recruitment
0
10
20
30
40
50
60
70
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
year
recr
uit
s (m
illi
ons)
run 7 Total Biomass
0
5
10
15
20
25
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
year
bio
mas
s (0
00s
mt)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
Year
Fish
ing
Mor
talit
y
DPWG
2009
2010
0
2000
4000
6000
8000
10000
12000
14000
Year
SSB
(m
t)
DPWG
2009
2010
Comparison to previous
assessments
NEFSC Spring offshore survey-2004
1st Quartile (Lowest) 2nd Quartile 3rd Quartile
4th Quartile (Highest) 100 Fathom Depth
35.00
36.00
37.00
38.00
39.00
40.00
41.00
42.00
43.00
Latit
ude
-76.00 -75.00 -74.00 -73.00 -72.00 -71.00 -70.00 -69.00 -68.00Longitude
Catch NumbersBLACK SEA BASS
Spring 2005
NEFSC Spring offshore survey-2005
NEFSC Spring offshore survey-2006
NEFSC Spring offshore survey-2007
NEFSC Spring offshore survey-2008
NEFSC Spring offshore survey - 2009