| CRD 02-02 Table 16. Estimates of instantaneous total mortality (Z) and fishing mortality (F)1 for Gulf of Maine Atlantic cod, 1964 - 2000, derived from NEFSC offshore spring and autumn bottom trawl survey data.2 |
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|
Time
Period |
Gulf of Maine
|
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|
Spring
|
Autumn
|
Geometric Mean
|
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|
Z
|
F
|
Z
|
F
|
Z
|
F
|
|
|
1964-1967
|
-
|
-
|
0.39
|
0.19
|
0.39
|
0.19
|
|
1968-1976
|
0.36
|
0.16
|
0.44
|
0.24
|
0.40
|
0.203
|
|
1977-1982
|
0.56
|
0.36
|
0.44
|
0.37
|
0.50
|
0.304
|
|
1983-1987
|
0.93
|
0.73
|
1.12
|
0.92
|
1.02
|
0.82
|
|
1988-1992
|
1.24
|
1.04
|
0.86
|
0.66
|
1.03
|
0.835
|
|
1993-1997
|
0.73
|
0.53
|
1.05
|
0.85
|
0.88
|
0.68
|
|
1998-1999
|
0.81
|
0.61
|
N/a
|
N/a
|
0.81
|
0.61
|
1 Instantaneous natural mortality (M) assumed to be 0.20. 2 Estimates derived from:
3 Excludes autumn 1967-1968 data (3+/4+) since these gave large negative Z value. 4 Excludes autumn 1976-1977 data (3+/4+) since these gave large negative Z value. 5 Excludes spring 1991-1992 data (4+/5+) since these gave unreasonably low Z value. |
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age 4+ for
year i to j/