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GFCM-SACSubCommittee on Stock Assessment (SCSA)
Izmir, 22-26 September 2008
ANCHOVY AND SARDINE STOCK ASSESSMENT IN THE GSA 17: 1975-2007
Santojanni A. 1a , Cingolani N. 1a , Donato F. 1a , Colella S. 1a ,Berlardinelli A. 1a , Giannetti G. 1a , Leonori I. 1b ,
Sinovcic G. 2 , Marceta B. 3
1a CNR-ISMAR-SPM, Fish Population Dynamics Unit, Ancona (Italy)
1b CNR-ISMAR-SPM, Marine Acoustics Unit, Ancona (Italy)
2 Institute of Oceanography and Fisheries, Split (Croatia)
3 Fisheries Research Institute of Slovenia, Ljubljana (Slovenia)
Anchovy(Engraulis encrasicolus)
Sardine(Sardina pilchardus)
Mid-water trawlersItaly 2007: about 60 pairs
Purse seiners attracting fish by lightItaly 2007: 40-50 vessels (including “small” and “high” tonnage)
Fishery
Mid-water trawlers
Purse seiners
Data collection
since 1975
still ongoing:
- catches
- fishing effort
- length, weight of fish
- age (otolith readings)
12.00 13.00 14.00 15.00
43.00
44.00
45.00
46.00
T ries te G rado
M aranoL agunare
C aor le
C h iogg ia
G oro
R avenna
C esena tico
R im in i
C atto lica
F ano
A ncona
P.C iv itanova
P.S anG io rgio
S .B enede tto
G iulianova
6 0
1 0 0
2 0 0
4 0
G ariba ldiP orto
Hauls sampled by the observer on board of Italian fishing vesselsSantojanni et al. (2005) - Scientia Marina
Geo-referenced small pelagic catch per haul collected by means of electronic logbooks on board of fishing vessels
Virtual Population Analysis (VPA)
based on Laurec-Shepherd tuning
on abundance index derived from echo-survey.
Software:Darby C.D., Flatman S. 1994. Virtual Population Analysis: version 3.1 (Windows/Dos) user guide. Information Technology Series, MAFF Directorate of Fisheries Research, Lowestoft, 1: 85 pp.
Structure of the data used:
Split-year data were used assuming the first of June as the birth date of anchovy.
Calendar-year data were used for sardine.
Anchovy total catch
Sardine total catch
0
10000
20000
30000
40000
50000
60000
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split year
Ca
tch
(to
nn
es
)
Slovenia and CroatiaItaly
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
Ca
tch
(to
nn
es
)Slovenia and CroatiaItaly
Age frequency distribution of the total catch
25.1
40.2
21.7
9.1
3.00.9 0.1
0
5
10
15
20
25
30
35
40
45
Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6
% Average 1976-2007
4.50
23.6125.05
20.23
14.85
6.68
3.120.94 0.63 0.28 0.10 0.01 0.00
0
5
10
15
20
25
30
Age0
Age1
Age2
Age3
Age4
Age5
Age6
Age7
Age8
Age9
Age10
Age11
Age12
% Average 1975-2007
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year
Age 4
Age 3
Age 2
Age 1
Age 0
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
Age 6+
Age 5
Age 4
Age 3
Age 2
Age 1
Age 0
Abundance at sea from echo-survey
Stock biomass
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
To
nn
es
Stock biomass
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
To
nn
es
Sardine
Anchovy
Natural mortality rate M
AnchovyM = 0.6 and M = 0.8 on the basis of
- values in the literature
- the highest values of life span in our data are 4, 5, 6 years
- precautionary approach for M = 0.6
SardineM = 0.5 on the basis of
- values in the literature
- the highest values of life span in our data are 10, 11, 12 years
Anchovy: M = 0.54 and M = 0.81 were reported for the Catalan Sea by Pertierra and Lleonart (1996).
Sardine: M = 0.5 was obtained in the Adriatic Sea by Sinovcic (1986). Values of M from 0.29 to 0.62 were reported for the Catalan Sea by Pertierra and Perrotta (1993).
The criterion to select M taking into account the inverse relationship between Z and longevity was adopted for small pelagics by other authors. As reported in a recent GLOBEC report (Barange, 2001), Pacific sardine (Sardinops sagax) is usually assumed to have a relatively low annual natural mortality rate, M = 0.4, and a lifespan of about 10 years, whereas for northern anchovy (Engraulis mordax) M = 0.8 is associated to a lifespan of about 4 years.Barange M. (ed.) 2001. Report of the first meeting of the SPACC/IOC study group on the “Use of environmental indices in the management of pelagic fish populations”, 3-5 September 2001, Cape Town, South Africa. GLOBEC Special Contribution, 5, 122 pp.Pertierra J.P., Lleonart J. 1996. NW Mediterranean anchovy fisheries. Scientia Marina, 60 (Suppl. 2): 257-267.Pertierra J.P., Perrotta R.G. 1993. On the population dynamics of sardine, Sardina pilchardus Walbaum, 1792, from the Catalan Sea (northwestern Mediterranean). Scientia Marina, 57: 235-241.Sinovcic G. 1986. Estimation of growth, mortality, production and stock size of sardine, Sardina pilchardus (Walb.), from the middle Adriatic. Acta Adriatica, 27: 67-74.
Natural mortality rate M
Hoenig’s equation:
Ln Z = 1.44 – 0.982 Ln tmax
“based largely on data from unexploited stocks”,
thus with Z being very close to M.
Hoenig J.M. 1983. Empirical use of longevity data to estimate mortality rates. Fishery Bulletin, 82: 898-903.
Hewitt D.A., Hoenig J.M. 2005. Comparison of two approaches for estimating natural mortality based on longevity. Fishery Bulletin, 103: 433-437.
Natural mortality rate M tmax (year) predicted Z
1 4.22
2 2.14
3 1.43
4 1.08
5 0.87
6 0.73
7 0.62
8 0.55
9 0.49
10 0.44
11 0.40
12 0.37
13 0.34
14 0.32
15 0.30
16 0.28
17 0.26
18 0.25
19 0.23
20 0.22
Natural mortality rate M for sardine
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9Age (years)
Len
gth
(cm
)R square = 0.786
Parameter Value Standard error
Confidence interval at 95%
Lower limit Higher limit
Linf 18.783 0.226 18.339 19.226
k 0.379 0.028 0.324 0.435
t0 -2.302 0.185 -2.665 -1.939
Santojanni et al. (2008): GSA17, year 2007, EU-DCR
0
2
4
6
8
10
12
14
16
18
20
22
0 1 2 3 4 5 6 7 8 9 10 11 12Age (years)
Le
ng
th (
cm
)
Santojanni et al. (2008): Linf=18.78, k=0.38, t0=-2.30
Sinovcic (1986): Linf=20.50, k=0.46, t0=-0.50
M = 1.5 KJensen A.L. 1996. Beverton and Holt life history invariants result from optimal trade-off of reproduction and survival. Canadian Journal of Fisheries and Aquatic Science, 53: 820-822.
Jensen A.L. 2001. Comparison of theoretical derivations, simple linear regressions, multiple linear regression and principal components for analysis of fish mortality, growth and environmental temperature data. Environmetrics, 12: 591-598.
M = 0.57 with 0.38 [Santojanni et al. (2008), otoliths, fitting]
M = 0.69 with 0.46 [Sinovcic (1986), otoliths, Linf and k estimated by Gulland-Holt plot]
F/Z = 0.4 = > F = 2/3 M
Patterson K. 1992.Fisheries for small pelagic species: an empirical approach to management targets. Review of Fish Biology and Fisheries, 2: 321-338.
Anchovy: mid-year stock biomass estimated by VPA
0
100000
200000
300000
400000
500000
600000
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year
To
nn
es
Total catch
Stock biomass (M = 0.6)
Stock biomass (M = 0.8)
Anchovy: comparison between VPA and echo-survey
0
50000
100000
150000
200000
250000
300000
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year (VPA) - Year (Echo-survey)
To
nn
es
Total catch
VPA (M = 0.6)
VPA (M = 0.6): modified agedistribution in the tuning file
0
100000
200000
300000
400000
500000
600000
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year (VPA) - Year (Echo-survey)
To
nn
es
VPA (M = 0.6)
VPA (M = 0.8)
Echo-survey
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2002 2003 2004 2005 2006 2007Cohort
age4
age3
age2
age1
age0
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2002 2003 2004 2005 2006 2007
Cohort
age4
age3
age2
age1
age0
Anchovy: results from VPA with M = 0.6Total catch (t) Stock biomass (t) Ratio
Average 1976-2007 27890 122109 0.23
Average 2005-2007 42614 210452* 0.20
Fishing mortality rate F
Unweighted average of Ffor age 0-3
Average1976-2007
0.32
Average2005-2007
0.24
Weighted average of F for age 0-4
Average1976-2007
0.22
Average2005-2007
0.190.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year
FUnweighted average for age 0-3
Weighted average for age 0-4
*182955 with modified age distribution in the t.f.
0.00
0.10
0.20
0.30
0.40
0.50
Age 0 Age 1 Age 2 Age 3 Age 4+
FAverage 1976-2007
Anchovy: exploitation rate from VPA with M = 0.6
0.00
0.10
0.20
0.30
0.40
0.50
0.60
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Split-year
F/ZF/Z (F0-3 unweighted)F/Z (F0-4 weighted)
Threshold (Patterson, 1992)
Average 1976-2007 of F/Z (F0-3 unweighted): 0.34Average 2005-2007 of F/Z (F0-3 unweighted): 0.28
Average 1976-2007 of F/Z (F0-4 weighted): 0.26Average 2005-2007 of F/Z (F0-4 weighted): 0.24
07
05
9089
85
84
87 86
88
82
83
91
968197
9892
80
7779
78
94 95
9399
000102
03
04
06
0
500000
1000000
1500000
2000000
2500000
3000000
0 20000 40000 60000 80000 100000 120000 140000 160000 180000 200000
Spawning biomass in year x (tonnes)
Rec
ruits
in y
ear x
+1 (i
ndiv
idua
ls *
10-4
)
Year n+1 specified near the data points
Anchovy stock-recruitment relationship(derived from VPA with M = 0.6)
Sardine: mid-year stock biomass estimated by VPA
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
1000000
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
To
nn
es
Total catch
Stock biomass
Sardine: comparison between VPA and echo-survey
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
1000000
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
To
nn
es
Total catch
Stock biomass (VPA)
Stock biomass (Echo-survey)
Sardine: results from VPATotal catch (t) Stock biomass (t) Ratio
Average 1975-2007 44439 444309 0.10
Average 2005-2007 17489 90928 0.19
Fishing mortality rate F
Unweighted average of Ffor age 0-5
Average1975-2007
0.27
Average2005-2007
0.48
Weighted average of F for age 0-6
Average1975-2007
0.12
Average2005-2007
0.170.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
FUnweighted average for age 0-5
Weighted average for age 0-6
0.00
0.10
0.20
0.30
0.40
0.50
Age0
Age1
Age2
Age3
Age4
Age5
Age6+
FAverage 1975-2007
Sardine: exploitation rate from VPA
0.00
0.10
0.20
0.30
0.40
0.50
0.60
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07
Year
F/Z
F/Z (F0-5 unweighted)
F/Z (F0-6 weighted)
Threshold (Patterson, 1992)
Average 1975-2007 of F/Z (F0-5 unweighted): 0.32Average 2005-2007 of F/Z (F0-5 unweighted): 0.48
Average 1975-2007 of F/Z (F0-6 weighted): 0.19Average 2005-2007 of F/Z (F0-6 weighted): 0.25
Sardine stock-recruitment relationship(derived from VPA)
0705
030201
0099 98
92
9493
77 78
76
7991
97 96
80
95
90
82
8187
85
86
83
8488
89
0406
0
500000
1000000
1500000
2000000
2500000
3000000
0 100000 200000 300000 400000 500000 600000 700000 800000
Spawning biomass in year x (tonnes)
Rec
ruits
in y
ear x
+1 (i
ndiv
idua
ls *
10-4
)
Year n+1 specified near the data points
a)
0
50000
100000
150000
200000
250000
300000
76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
b)
0
50000
100000
150000
200000
250000
300000
76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
c)
0
50000
100000
150000
200000
250000
300000
76 78 80 82 84 86 88 90 92 94 96 98 00 02 04 06 08 10 12Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
Simulations of anchovy stock biomass and total catch for the period 2007-2012 from ISMAR report to Italian Ministry
Na+1, t+1 = Na, t exp( –(Fa + M) )
Ca, t = [ Fa / (Fa + M) ] [ 1 – exp( –(Fa + M) ) ] Na, t
M = 0.6
Fa : the level F is the average 1999-2006.
Three scenarios of recruitment:
“high”, “low”, “mixed”.
a)
0
200000
400000
600000
800000
1000000
1200000
75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 05 07 09 11
Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
b)
0
200000
400000
600000
800000
1000000
1200000
75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 05 07 09 11
Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
c)
0
200000
400000
600000
800000
1000000
1200000
75 77 79 81 83 85 87 89 91 93 95 97 99 01 03 05 07 09 11
Anno
To
nn
ella
te
Catture totali F F x 1,3 F x 1,5Biomassa dello stock F F x 1,3 F x 1,5
Na+1, t+1 = Na, t exp( –(Fa + M) )
Ca, t = [ Fa / (Fa + M) ] [ 1 – exp( –(Fa + M) ) ] Na, t
Simulations of sardine stock biomass and total catch for the period 2007-2012 from ISMAR report to Italian Ministry
M = 0.5
Fa : the level F is the average 1999-2006.
Three scenarios of recruitment:
“high”, “low”, “mixed”.
The stock biomass of anchovy dropped at a very low level in 1987. After this collapse, recovery took place, but fluctuations still occurred, in particular in recent years. It should be remembered that strong changes over time are commonly observed in the abundance of small pelagics, in particular anchovies (Jacobson et al., 2001). The recent exploitation rate F/Z was under the Patterson’s threshold 0.4, but on the other hand, an increase was observed in both western and eastern side catches of most recent years: the mentioned average for the period 2005-2007, 42614 tonnes, was quite over the average for the previous years from 1995 to 2004, 27353 tonnes. The stock can be considered as fully exploited.
Jacobson L.D., De Oliveira J.A.A., Barange M., Cisneros-Mata M.A., Felix-Uraga R., Hunter J.R., Kim J.Y., Matsuura Y., Niquen M., Porteiro C., Rothschild B., Sanchez R.P., Serra R., Uriarte A., Wada T. 2001. Surplus production, variability, and climate change in the great sardine and anchovy fisheries. Canadian Journal of Fisheries and Aquatic Science, 58(9): 1891-1903.
Management advice for both species
The most recent values of the exploitation rate F/Z of sardine stock, obtained using unweighted F0-5 , were higher than the Patterson’s threshold 0.4: the average for the period 2005-2007 was equal to 0.48 (0.32 for the whole period). Moreover, a strong decline of stock biomass occurred after the peak in the first half of 1980s; this declines was continuous till the end of 1990s: then, biomass was quite stable around values slightly lower than 100000 tonnes, which corresponded to the lowest abundances of the time series. The stock can be considered as overexploited.
Management advice for both species
It should be noted that Adriatic small pelagic fishery is multispecies and effort on anchovy cannot be separated from effort on sardine, so that most of the management decisions should be taken considering both species. In conclusion, it is recommended not to increase the fishing effort: such an increase would be particularly unwise for sardine.
Management advice for both species