Witch flounder - Northeast Fisheries Science Center
G. Witch Flounder by S. Wigley and L. Col 1.0 Background Witch flounder, Glyptocephalus cynoglossus, are assessed as a unit stock from the Gulf of Maine southward. An analytical assessment was last conducted for this species in 2003 (Wigley et al. 2003) for SAW/SARC 37 (NEFSC 2003). The 2003 assessment indicated average fishing mortality (ages 8-9, unweighted) increased from 0.26 in 1982 to 0.67 in 1985, declined to 0.22 in 1992, increased to 1.13 in 1996, then declined to 0.41 in 2002. Spawning stock biomass declined from 16,897 tons in 1982 to about 3,800 tons in 1996 and then increased sharply to 18,296 mt in 2002. Since 1982, recruitment at age 3 has ranged from approximately 3 million fish (1984 year class) to 67.6 million fish (1997 year class) with a mean (1979 – 2000 year classes) of 19.6 million fish. This report updates catch through 2004, survey indices through spring 2005, and estimates 2004 fishing mortality and spawning stock biomass for stock status determination. 2.0 Assessment Data The Fishery Significant proportions of the U.S. nominal catch have been taken from both the Georges Bank and Gulf of Maine regions. Canadian landings from both areas have been minor (not more than 68 mt annually). USA landings generally increased from the early 1960s, peaked in 1984 at 6,666 mt. Subsequently, landings declined and have fluctuated about 2,300 mt. In 2004, landings were 2,917 mt (Table G.1 and Figure G.1). Sampling intensity of landings during 2003 and 2004 increased over recent years (Table G.2), however, as in previous years, it was necessary to pool some quarters for some market categories. To estimate landings at age and mean weights at age, quarter, semi-annual or annual age-length keys were applied to corresponding commercial landings length frequency data by market category. Discard estimation Discards-at-age were updated using the same estimation methods used in the 2003 assessment for the northern shrimp fishery and the large-mesh otter trawl fishery (Wigley et al 2003). Discards from the northern shrimp fishery were estimated using two methods: when no observer data were available (1982-1988, 1998-2002), a regression of age 3 fish in the autumn NEFSC survey and observed discard rates were used to estimate ratios of discard weight to days fished (d/df) ratios. When observer was available (1989-1997, 2003-2004), d/df ratios were calculated by fishing zone (a surrogate for depth). To estimate discard weight, the mean discard ratio (weighted by days fished in each fishing zone) was expanded by the days fished in the northern shrimp fishery. For 2003 and 2004, witch flounder discards in the northern shrimp fishery were estimated to be 2-185
near zero. This is attributed to the short northern shrimp season and the shift in effort to nearshore waters, inshore of the witch flounder distribution Witch flounder discarded in the northern shrimp fishery range in age from 0 to 6, with the majority at ages 1-3. The number of fish discarded in the shrimp fishery is small compare to the landings (Figure G.2). The estimation of large-mesh otter trawl discards is based upon two methods. For 1982 to 1994, a method which filters survey length frequency data through a commercial gear retention ogive and a culling ogive was used and then a semi-annual ratio estimator of survey-filtered ‘kept’ index to semi-annual numbers landed was used to expand the estimated ‘discard’ survey index to numbers of fish discarded at length. For 1989 to 2004, discard weight to kept weight ratios (d/k) were calculated from observer data on a semi-annual basis. Total discard weight was derived by multiplying the d/k ratio by the commercial landings. Given the limited sample size (number of trips) prior to 1995, discards at age were estimated from 1995 onward. Observed discard length frequencies are used to estimate discarded fish at length. Semi-annual numbers of fished discarded were apportioned to age using the corresponding seasonal NEFSC survey age/length key. Witch flounder discarded in the large mesh otter trawl fishery range in age from 0 to 6, with the majority at ages 4 to 5. The number of fish discarded in the large-mesh otter trawl fishery is small compare to the landings (Figure G.2). The total catch (landings + otter trawl discards + shrimp trawl discards) at age is presented in Table G.3 and Figure G.2. The age composition data reveal strong 1979- 1981 year classes; the 1989 and 1993 year classes also appear strong. The poor 1984 year class is also evident as well as a truncated age-structure since the early 1990’s. As observed in recent years, the mean weights-at-age in the catch continue to decline (Figure G.3). Research Vessel Survey Indices The NEFSC bottom trawl survey indices generally declined from the early 1960s to record low levels in the late 1980s and early 1990s. Since then survey indices increased but have exhibited a declining trend since 2000 (Table G.4, Figure G.4a-b). Survey age compositions (mean number per tow at age)are presented in Table G.5. The survey mean weights and mean lengths at age show a similar decline as reported in the commercial landings. Survey maturity-at-age has remained stable in recent years. 3.0 Assessment Results Since the last assessment, minor VPA software changes have occurred and additional age and length data have become available. These changes had only a minor impact on the SARC 37 assessment results (Table G.6). For the current assessment, the VPA formulation is the same as the 2003 assessment and uses catch (landings and discards) through 2004 and NEFSC spring and autumn survey indices through 2005 and 2004, respectively, to estimate stock sizes for ages 3 to 10. The VPA had a mean square residual of 0.81, the coefficients of variation (CVs) for estimated ages ranged between 27% and 65% (Table G.6), and the CVs for survey catchability coeffiecients (q) were consistent, ranging from 11% to 25%.
2-186
VPA results indicate average fishing mortality (ages 8-9, unweighted) increased from 0.26 in 1982 to 0.68 in 1985, declined to 0.22 in 1992, increased to 1.12 in 1996, then declined to 0.20 in 2004 (Tables G.7 and G.8, Figure G.5). Spawning stock biomass declined steadily from 16,897 mt in 1982 to 3,901 mt in 1996, and has increased to21,175 mt in 2004 (Tables G.7 and G.8, Figure G.6). Since 1982, recruitment at age 3 has ranged from approximately 3 million fish (1984 year class) to 45 million fish (1997 year class) with a mean of 15.5 million fish (median of 14 million; Table G.7, Figure G.6). The addition of the 2000 to 2002 year classes to the stockrecruit data continued the negative trend observed in this relationship in the previous assessment. The current age composition of the spawning stock is approaching the equilibrium age composition. However, given the recent poor year classes (2000-2002), spawning stock biomass will eventually decline as these poor classes enter the fishery (Figure G.6). The retrospective analysis indicates that average F was underestimated in the late 1990s and early 2000s (Figure G.7a) and spawning stock biomass was consistently overestimated (Figure G.7b). The retrospective analysis indicated a pattern of relatively consistent estimates of the number of age 3 recruits, with the notable exception of the 1992, 1993 and 1996 year classes, which were considerably overestimated (Figure G.7c). Bootstrap results suggest that the estimates of F and spawning stock biomass are relatively precise with CVs of 30% and 14%, respectively. The 80% confidence interval for F2004=0.20 was 0.15 and 0.28, and for SSB2004 = 21,175 mt the 80% confidence interval was 18,192 mt and 26,121 mt.
4.0 Biological Reference Points Based on yield and spawning stock biomass per recruit analyses and the arithmetic mean of the VPA age 3 recruitment (NEFSC 2003), the biological reference points are: SSBmsy = 25,248 mt Fmsy = F40% = 0.23 MSY = 4,375 mt. The 2004 spawning stock biomass (21,175 mt) was above ½ SSBmsy (12,624 mt), the overfished threshold, and 2004 fishing mortality (0.20) was below Fmsy (0.23), the overfishing threshold; therefore, witch flounder was not overfished and overfishing was not occurring in 2004. Amendment 13 Projections and current status There is no formal rebuilding program required for witch flounder, thus there is not a rebuilding biomass trajectory. Amendment 13 is designed to end overfishing of witch flounder; a spawning stock biomass trajectory at Fmsy was conducted for Amendment 13. The spawning stock biomass estimates from this assessment are below what was projected for the Amendment 13. The fishing mortality estimated for 2004 is below the Fmsy used in the Amendment 13 projections (Figure G.8).
2-187
5.0 Panel Comments The Panel discussed the adequacy of the age-length information used to estimate the commercial landings-at-age. There is now sufficient information for some of the years to develop estimates by quarter and market category, and given continued adequate sampling, this should be continued in the future. This may be important as the fishery has apparently shifted from peewees and smalls to smalls and mediums. There is some caution about simply using the number of samples as an indication about sample size. In the past, a sample normally consisted of about 100 fish. With potentially smaller catches, this criterion for sampling has been relaxed in order to get samples. Given that witch flounder is very slow growing, the pooling effect may not be as much of an issue. There was some discussion of the apparent expansion in age structure of the discards beginning in 1995. It was suggested that this may be an artifact of the change in estimation method beginning in 1995. However, another expansion of the age structure was apparent in 2002 with the same method. Observed discards of large fish may be due to the inclusion of trips from other fisheries that do not require use of a DAS, although trips targeting Loligo were excluded. The panel discussed the recent declines in mean weights. It is possible that fishing patterns have changed in relation to the distribution of the stock to areas that are less favorable for growth. The distribution of the fishery and survey should be investigated in the future. The short term decline in size at maturity in the late 1980s was discussed. This short term decline coincided with very low biomass. It was not possible to examine the decline on an annual basis due to low sampling (sparse data). The difference in current estimate of 2004 biomass compared to the estimate projected from the last assessment may be due to an increase in the estimate of realized F being higher than that used in the projections, lower recruitment than expected and a retrospective underestimate of SSB. The Panel noted that the recent increase in SSB has been mostly driven by the good recruitment of the 1996-1998 year classes. If catches remain constant, SSB will eventually decline as the following poor year classes enter the fishery. Projection Advice - The Panel recommended using an average of the mean weights from 20022004 for projections. The same years are suggested for the partial recruitment and maturity (5 year average of 2001-2005) vectors. Given the declining trend in recruitment, the panel recommended using the estimated value of the 2002 year class although it was an uncertain estimate. For 2006-2008, the panel suggested re-sampling just the 2000-2002 year classes (not the entire series). Given that witch flounder is long-lived and late maturing, the values of recruitment should not be influential in the projections. 6.0 Sources of Uncertainty &
Low frequency of samples across market category and quarter results in imprecise mean
2-188
weights at age and estimates of numbers at age. &
Lack of data to support direct estimates of discards at age requires use of various surrogate survey-based methods.
&
Retrospective patterns suggest that estimates of SSB may be overestimated (e.g. future assessments may have lower estimates of SSB).
&
The research bottom trawl survey catches very few witch flounder; in most years, the stratified mean number per tow of witch flounder is less than 5 fish. Abundance of witch flounder in the late 1980s and early 1990's may have gone below levels that provide reliable estimates of trends in abundance and biomass
7.0 Acknowledgments We thank all those who diligently collected data from the commercial fisheries (dock-side and at-sea) and the research vessel surveys. We thank J. Burnett for providing the age determinations used in the assessment. We thank all the members of the Groundfish Assessment Review Meeting for their review and helpful comments. 8.0 References Burnett, J. and S.H. Clark. 1983. Status of witch flounder in the Gulf of Maine – 1983. NMFS/NEFC, Woods Hole Laboratory Ref. Doc. No. 83-36, 31 p. Lange, A.M.T. and F.E. Lux. 1978. Review of the other flounder stocks (winter flounder, American plaice, witch flounder, and windowpane flounder) off the northeast United States. NMFS, NEFC, Woods Hole Lab. Ref. Doc. No. 78-44, 53 pp. NEFSC [Northeast Fisheries Science Center]. 2003. Report of the 37th Northeast Regional Stock Assessment Workshop (37th SAW), Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. Doc. 03-16, 597 p. Wigley, S.E., J. K.T. Brodziak, and L. Col. 2003. Assessment of the Gulf of Maine and Georges Bank witch flounder stock for 2003. Northeast Fish. Sci. Cent. Ref. Doc. 03-14, 186 p.
2-189
Table G.1. Witch flounder landings, discards and catch (metric tons, live) by country, 1937-2004 [1937-1959 provisional landings reported in Lange and Lux, 1978; 1960-1963 reported to ICNAF/NAFO (Burnett and Clark, 1983)].
LANDINGS Year
1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981
USA Subarea 4, 5 & 6
1255 1022 976 1226 1381 2140 2935 3370 2807 2542 3112 3220 2934 2523 1839 2127 1871 2469 3501 2878 3128 3442
USA Subarea 3
USA Total 5000 3600 3100 3000 2000 1800 1000 1000 1000 1500 1500 1000 3600 3000 2600 3700 4200 4000 2400 2000 1000 1000 1000 1255 1022 976 1226 1381 2140 2935 3370 2807 2542 3112 3220 2934 2523 1839 2127 1871 2469 3501 2878 3128 3442
2-190
CAN
2 1 27 37 22 68 63 56 19 35 13 10 9 13 5 11 18 17 18 7
Other
121 502 311 249 191 1310 130 2860 2568 629 292 217 6 13 6 1
Total 5000 3600 3100 3000 2000 1800 1000 1000 1000 1500 1500 1000 3600 3000 2600 3700 4200 4000 2400 2000 1000 1000 1000 1255 1024 977 1374 1418 2664 3314 3682 3054 3852 3261 6115 5515 3162 2140 2357 1882 2493 3525 2895 3147 3449
USA Discards
USA Catch
Table G.1. continued. Witch flounder landings, discards and catch (metric tons, live).
LANDINGS Year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
USA Subarea 4, 5 & 6 4906 6000 6660 6130 4610 3450 3262 2068 1465 1777 2227 2601 2665 2209 2087 1771 1848 2121 2439 3019 3188 3124 2917
USA Subarea 3
255 539 346 358 297 2
USA Total 4906 6000 6660 6385 5149 3796 3620 2365 1467 1777 2227 2601 2665 2209 2087 1771 1848 2121 2439 3019 3188 3124 2917
2-191
CAN 9 45 15 46 67 23 45 13 12 7 7 10 34 11 10 7 10 19 53 32 34 30
Other
Total 4915 6045 6675 6431 5216 3819 3665 2378 1479 1784 2234 2611 2699 2220 2097 1778 1858 2140 2492 3051 3222 3154 2917
USA Discards 48 162 100 61 25 47 60 133 184 95 171 376 422 193 254 300 286 213 115 224 279 381 233
USA Catch 4954 6162 6760 6191 4635 3497 3322 2201 1649 1872 2398 2977 3087 2402 2341 2071 2134 2334 2554 3243 3467 3505 3150
348 5 527 128
475 5 680 135
462 5 804 154
465 12 1530 319
384 6 662 123
1982 mt n len age
1983 mt n len age
1984 mt n len age
1985 mt n len age
1986 mt n len age
Year 1981 mt n len age
309 3 307 60
377 1 105 29
322 9 1112 250
250 2 232 30
1 2 194 55
Quarter 1 Small Med. 260 7 . . . . . .
356 5 515 89
613 2 229 50
1036 4 400 76
910 3 265 55
726 6 626 150
Large 517 . . .
654 5 558 106
697 5 657 106
513 7 970 186
471 5 685 131
342 1 126 30
421 4 410 97
453 4 426 77
393 1 117 25
286 1 96 16
73 2 209 55
Quarter 2 Small Med. 269 32 . 1 . 101 . .
595 5 413 129
850 7 698 153
1000 7 775 180
1037 5 520 125
886 2 216 50
Large 694 1 103 26
2-192
375 4 302 63
526 7 795 97
403 8 1045 210
298 8 1008 152
287 2 189 50
238 3 364 75
291 7 800 138
248 1 106 28
154 3 123 0
170 2 210 50
Quarter 3 Small Med. 242 13 . 1 . 89 . 25
354 4 406 100
553 6 684 113
653 2 191 53
758 8 981 159
739 6 514 150
Large 607 . . .
312 5 416 87
433 8 824 161
429 4 615 105
257 6 677 180
278 3 307 81
212 3 337 75
310 2 264 25
286 2 243 44
169 3 344 75
201 4 393 105
Quarter 4 Small Med. 230 0 1 . 105 . 25 .
238 2 233 52
408 4 349 29
586 1 91 25
613 . . .
669 2 189 50
Large 453 1 100 25
4448 49 4923 1056
5976 65 7361 1297
6331 51 6469 1336
5678 49 5611 1058
4720 37 3700 954
90
92
124
116
128
Sampling All Ratio 3324 5 498 101
Table G.2. Summary of USA commercial witch flounder landings (mt), number of length samples (n), number of fish measured (len) and number of age samples (age) by market category and quarter for all gear types, 1981 - 2004. The sampling ratio represents the amount of landings per length sample.
424 5 335 70
230 1 94 25
113 1 134 15
71 5 262 53
180 4 259 42
1988 mt n len age
1989 mt n len age
1990 mt n len age
1991 mt n len age
1992 mt n len age
86 2 241 46
56 2 224 50
125 2 199 40
174 2 201 50
304 4 407 89
Table G.2. continued. Quarter 1 Year Small Med. 1987 mt 349 211 n 1 1 len 85 145 age 25 25
82 2 185 52
58 3 401 80
107 3 199 45
148 2 222 49
271 5 465 106
Large 228 2 200 50
466 7 501 78
219 7 537 93
147 6 335 81
255 2 230 50
436 5 344 71
Small 432 4 323 77
163 1 125 25
151 2 239 45
168 3 296 70
264 2 236 46
393 5 544 110
Quarter 2 Med. 317 2 228 47
174 2 235 25
167 1 125 25
147 1 100 25
251 1 27 25
389 3 429 77
Large 387 3 316 76
2-193
205 7 477 86
192 4 212 49
100 6 349 69
98 2 150 40
184 5 396 70
Small 296 5 354 78
115 1 121 25
142 2 165 49
119 2 247 41
145 2 206 51
176 4 359 100
Quarter 3 Med. 203 5 583 113
138 1 117 25
184 3 249 52
129 2 145 50
156 1 100 25
208 3 295 75
Large 247 4 400 95
212 2 129 27
168 5 300 66
84 7 381 103
85 1 125 25
140 3 229 61
Small 298 2 204 48
97 . . .
108 4 410 97
79 2 201 48
107 2 202 47
140 4 402 95
Quarter 4 Med. 203 3 261 64
116 1 46 23
121 3 274 58
85 . . .
103 . . .
131 3 356 69
Large 202 2 178 51
2034 30 2436 454
1637 41 3398 717
1403 35 2586 587
2016 18 1793 433
3196 49 4561 993
All 3373 34 3277 749
68
40
40
112
65
69
Sampling Ratio
Small 350 7 830 55
403 . . .
336 3 208 53 313 5 504 59
313 6 557 77
372 5 339 45
386 3 282 15
Year 1993 mt n len age
1994 mt n len age
1995 mt n len age 1996 mt n len age
1997 mt n len age
1998 mt n len age
1999 mt n len age
Table G.2.
48 . . .
39 2 206 50
40 3 350 68
91 3 348 84 57 2 218 45
143 . . .
Quarter 1 Med. 112 1 100 25
19 . . .
19 1 128 19
25 3 351 70
77 3 347 89 36 3 292 78
98 . . .
Large 110 . . .
616 4 308 62
587 4 238 30
478 9 812 108
586 6 459 81 545 5 331 53
505 3 560 59
Small 442 7 741 56
79 . . .
79 1 88 .
86 4 418 73
117 3 367 75 86 2 240 50
183 5 532 104
Quarter 2 Med. 192 1 107 27
31 . . .
31 1 135 29
41 3 309 77
100 5 517 135 60 1 127 26
154 6 749 134
Large 161 1 100 26
2-194
436 17 1110 143
380 5 484 47
398 9 783 98
399 . . . 458 5 494 59
390 5 356 44
Small 263 9 728 74
67 2 201 .
40 3 186 22
55 3 308 81
61 . . . 56 4 464 86
122 5 648 113
Quarter 3 Med. 122 1 85 .
30 3 306 32
20 1 100 .
27 1 107 20
70 . . . 44 4 468 101
117 1 105 26
Large 150 5 499 73
353 11 775 91
239 . . .
265 9 505 73
304 2 217 27 363 5 343 60
383 5 342 56
Small 331 . . .
38 1 109 16
26 . . .
31 1 128 18
48 . . . 42 3 277 70
91 3 368 60
Quarter 4 Med. 96 . . .
18 . . .
14 . . .
16 1 50 23
40 1 94 25 28 3 348 69
80 4 407 82
Large 106 . . .
2121 41 3091 359
1849 23 1904 242
1775 52 4678 786
2212 26 2557 569 2088 42 4106 756
2670 37 4067 678
All 2435 32 3190 336
51
80
34
50
85
72
76
Sampling Ratio
603 4 324 57
609 5 480 73
2004 mt n len age
740 5 363 75
2002 mt n len age
2003 mt n len age
583 8 744 125
2001 mt n len age
Year 2000 mt n len age
76 13 1244 226
70 6 423 93
79 1 121 16
71 4 422 64
Quarter 1 Small Med. 477 53 31 2 2253 91 393 10
Table G.2. continued.
16 23 1813 505
17 6 162 60
18 2 107 50
17 2 134 42
Large 17 . . .
598 8 675 151
684 10 881 131
774 3 212 65
824 3 237 48
90 5 549 96
108 5 482 64
103 5 518 73
99 3 352 48
Quarter 2 Small Med. 583 93 47 . 2445 . 463 .
23 8 576 169
30 10 433 174
26 3 209 64
30 2 159 64
Large 27 . . .
2-195
758 5 541 58
865 11 943 172
849 5 389 88
699 8 594 126
113 5 356 95
125 6 531 91
114 2 150 34
98 2 209 34
Quarter 3 Small Med. 555 89 17 1 994 105 224 20
30 2 48 10
36 16 552 246
29 3 194 62
28 3 213 46
Large 28 . . .
546 19 1838 49
533 7 654 99
400 3 262 49
507 5 313 61
45 5 420 72
43 7 632 120
45 2 226 30
50 3 232 49
Quarter 4 Small Med. 451 50 5 5 308 558 67 92
13 15 83 .
10 13 525 191
9 2 115 49
13 . . .
Large 16 2 217 51
2917 113 8623 1504
3124 101 6542 1498
3186 35 2815 655
3019 43 3609 707
26
31
89
70
Sampling All Ratio 2439 21 110 6971 1320
Table G.3.
0
0.03 0.00 0.00 0.00 0.00 2.08 0.42 0.85 1.46 3.06 2.84
113.76 8.06 2.68 5.21 8.68
49.78
32.11
21.61
12.33 2.32 0.00 0.00
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
0.00
2.40
20.24
96.96
169.95
252.94
392.89
74.91
32.68
49.95
1368.48
85.80
44.35
17.90
6.29
10.69
14.66
18.92
0.53
0.34
0.33
0.02
0.06
1
7.41
11.21
17.42
66.42
119.51
194.45
294.20
102.92
50.83
655.51
496.44
129.59
159.43
23.26
95.30
50.32
130.29
79.93
3.86
3.47
0.88
4.28
1.72
2
4
6
7
25.36
50.07
40.96
69.93
103.50
160.92
331.23
135.29
121.89
628.79
41.97
417.23
399.46
441.77
343.93
447.05
600.27
22.25
22.95
123.58
146.61
337.11
190.49
2-196
325.78
391.72
744.95
343.22
286.46
526.08
556.89
1058.45
524.44
370.28
1001.80
1807.30
1255.56
405.76
634.14
436.25
139.91
181.26
377.07
1176.12
1466.31
1346.17
1064.47
1078.47
1308.71
1226.69
938.11
451.20
1095.77
1063.74
1015.95
1207.69
1041.23
2759.91
1418.95
859.20
863.74
1103.15
65.16
264.30
467.06
1516.79
2118.21
2002.70
1520.76
1207.67
1538.12
1743.54
1394.91
1088.86
1168.80
1461.98
1415.46
1293.41
1362.86
1714.50
1287.99
918.12
935.96
575.43
255.61
314.33
658.27
1280.06
2775.35
1936.24
1739.59
1575.12
1475.40
1500.94
1909.68
2141.29
1715.57
1689.67
1201.10
1611.62
1019.07
1430.48
851.35
826.85
597.19
716.98
235.77
273.86
759.35
1382.70
1574.70
1566.90
1524.90
1486.50
1590.20
665.20
USA Commercial Catch in Numbers (1000's) at Age
3
AGE 5
1146.27
1565.83
1276.60
1455.26
1009.04
765.34
371.44
593.77
263.23
268.54
196.69
585.56
201.64
244.55
471.07
882.12
1154.10
870.90
834.90
1247.90
1497.50
977.80
656.00
8
797.89
749.60
642.49
632.43
558.09
252.52
142.05
84.55
215.48
97.53
539.15
218.77
177.88
292.11
333.93
349.65
401.50
480.60
412.70
606.00
696.70
737.70
399.50
9
324.36
435.29
95.14
427.38
93.13
31.57
15.54
49.79
57.05
269.49
113.49
278.53
120.04
313.56
81.35
123.39
266.70
252.40
222.80
400.40
375.10
510.40
239.40
10
291.65
348.74
201.85
309.51
234.60
54.36
70.30
70.08
113.62
156.84
324.29
390.48
377.01
257.77
177.49
348.00
597.50
489.40
758.20
1359.20
1718.80
1675.50
1578.40
11+
Total USA commercial catch [landings + shrimp trawl discards + large-mesh otter trawl discards using survey filter and FOP] in numbers, (thousands of fish), mean weight (kg) and mean length (cm) at age of witch flounder, 1982 - 2004.
0.015
0.006
0.004
0.009
0.004
0.004
0.003
0.003
0.005
0.005
0.004
0.004
0.003
0.003
0.003
0.003
0.003
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
1982-2004 2000-2004
Mean
2004
0.004 0.003
0.017
1986
2003
0.017
1985
0.010 0.007
0.008
0.007
0.006
0.006
0.006
0.006
0.023
0.019
0.007
0.004
0.009
0.007
0.014
0.012
0.012
0.006
0.017
1984
0.002 0.009
0.000
0.030 0.034
0.053
0.039
0.032
0.023
0.024
0.024
0.024
0.033
0.031
0.024
0.019
0.027
0.026
0.035
0.029
0.034
0.017
0.033
0.026
0.023
0.040
0.038
0.038
0.091 0.086
0.098
0.070
0.110
0.089
0.066
0.068
0.070
0.070
0.060
0.051
0.070
0.122
0.103
0.062
0.062
0.122
0.045
0.081
0.089
0.128
0.151
0.149
0.152
2-197
0.198 0.196
0.232
0.157
0.219
0.176
0.196
0.217
0.163
0.189
0.149
0.158
0.202
0.202
0.230
0.199
0.186
0.170
0.203
0.191
0.206
0.237
0.229
0.202
0.242
0.295 0.265
0.277
0.243
0.279
0.256
0.272
0.291
0.260
0.274
0.265
0.328
0.280
0.318
0.379
0.344
0.257
0.321
0.311
0.298
0.299
0.305
0.328
0.270
0.329
0.406 0.357
0.342
0.320
0.395
0.362
0.368
0.400
0.359
0.376
0.422
0.435
0.430
0.432
0.459
0.420
0.438
0.425
0.434
0.433
0.408
0.429
0.421
0.409
0.421
0.526 0.450
0.440
0.420
0.474
0.464
0.453
0.514
0.487
0.495
0.554
0.561
0.534
0.535
0.614
0.578
0.586
0.574
0.538
0.561
0.533
0.565
0.539
0.518
0.550
USA Commerical Catch Mean Weight (kg) at Age
0.642 0.536
0.540
0.503
0.552
0.550
0.534
0.584
0.584
0.627
0.708
0.690
0.691
0.666
0.739
0.702
0.688
0.682
0.668
0.686
0.676
0.691
0.664
0.613
0.727
Total USA commercial catch (landings + shrimp trawl discards + LM otter trawl discards). Age 0 1 2 3 4 5 6 7 8
1983
1982
Year
Table G.3. continued.
0.787 0.619
0.612
0.565
0.652
0.645
0.624
0.627
0.869
0.868
0.856
0.910
0.832
0.882
0.822
0.836
0.849
0.818
0.819
0.828
0.853
0.842
0.817
0.795
0.886
9
0.911 0.697
0.692
0.620
0.823
0.647
0.704
0.917
0.978
1.037
0.974
0.974
0.909
1.023
0.882
0.974
1.049
0.968
0.980
0.980
0.975
0.964
0.922
0.977
0.983
10
1.203 0.875
0.871
0.809
0.940
0.840
0.915
0.872
1.206
1.293
1.232
1.243
1.266
1.335
1.243
1.420
1.454
1.358
1.326
1.303
1.321
1.326
1.339
1.357
1.406
11+
Table G.4. Stratified mean number, weight (kg), length (cm), and individual weight (kg) per tow of witch flounder in NEFSC offshore spring and autumn bottom trawl surveys in Gulf of Maine-Georges Bank region (strata 22-30,36-40), 1963-2005.
Year 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Number per tow 4.83 3.74 6.39 2.70 5.35 8.20 6.23 3.72 5.50 4.20 3.87 2.91 8.46 8.14 3.64 6.41 3.00 5.18 2.07 1.01 1.43 1.95 0.63 1.68 1.26 1.47 3.13 1.88 1.36 2.22 4.27 3.15 3.45 4.41 8.10 5.20 3.80 3.36
SPRING Weight per tow 3.35 2.53 4.49 2.04 4.01 6.21 3.62 2.75 3.70 1.96 2.56 1.71 3.89 4.05 1.87 2.74 1.66 2.75 1.35 0.65 0.85 0.74 0.24 0.57 0.48 0.36 0.53 0.47 0.28 0.43 0.77 0.48 0.52 0.75 1.62 1.30 1.08 0.89
Length per tow 42.3 45.3 44.7 46.5 45.8 44.8 39.3 43.9 42.3 37.2 41.7 38.2 36.0 38.0 37.2 36.3 39.9 40.3 44.1 43.4 42.3 35.8 35.2 31.5 34.8 30.3 27.4 30.6 30.5 31.0 29.0 28.1 27.3 29.5 31.4 34.2 35.5 34.6
Ave. wt. per tow 0.695 0.676 0.702 0.756 0.749 0.758 0.581 0.739 0.673 0.467 0.662 0.587 0.460 0.497 0.513 0.427 0.554 0.531 0.650 0.646 0.590 0.382 0.378 0.341 0.383 0.245 0.170 0.248 0.204 0.195 0.179 0.153 0.151 0.171 0.199 0.250 0.285 0.264
Number per tow 5.52 2.89 3.94 7.80 3.01 4.82 5.81 4.89 4.32 3.24 3.18 2.38 1.66 1.34 5.06 4.04 1.94 2.62 3.66 0.99 4.72 4.37 2.76 1.59 0.48 1.38 0.89 2.00 2.08 0.94 5.15 2.21 4.74 5.38 5.11 3.70 5.92 6.63 7.94 4.31 2.66 3.82
AUTUMN Weight per tow 3.46 2.00 2.27 4.56 2.02 3.49 4.40 3.71 2.95 2.42 2.05 1.58 1.03 0.94 3.38 2.94 1.62 2.04 2.19 0.83 2.12 2.34 1.59 1.09 0.37 0.57 0.38 0.40 0.54 0.24 0.54 0.42 0.62 1.02 0.77 0.47 0.88 1.11 1.71 1.06 0.79 1.03
Length per tow 39.7 44.2 40.6 41.2 43.7 44.8 43.5 45.0 42.1 43.9 43.6 41.0 39.8 41.9 42.0 42.8 45.2 43.7 40.4 44.7 36.7 39.7 41.9 43.3 43.9 35.2 31.4 24.7 29.2 29.5 17.0 24.9 25.7 29.7 24.9 24.2 26.3 27.1 32.3 33.2 35.4 33.3
Ave. wt. per tow 0.627 0.691 0.577 0.584 0.673 0.724 0.757 0.760 0.683 0.747 0.646 0.666 0.621 0.699 0.669 0.727 0.838 0.777 0.600 0.842 0.448 0.534 0.577 0.683 0.774 0.414 0.423 0.200 0.258 0.254 0.105 0.191 0.132 0.189 0.150 0.127 0.148 0.167 0.216 0.247 0.298 0.271
Note: No significant differences in catchability were found for witch flounder between BMV and polyvalent doors, no significant differences were found between research vessels, therefore no adjustment have been made (Byrne and Forrester, MS 1991). Spring surveys during 1973-1981 were accomplished with a 41 Yankee trawl; in all other years, a 36 Yankee trawl was used. No adjustments have been made.
2-198
SPRING 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
1 0.060 0.000 0.044 0.000 0.000 0.000 0.000 0.000 0.023 0.023 0.008 0.042 0.054 0.149 0.107 0.041 0.017 0.072 0.112 0.106 0.007 0.105 0.023 0.000 0.009 0.011
2 0.230 0.050 0.042 0.071 0.103 0.000 0.000 0.000 0.023 0.013 0.000 0.000 0.009 0.112 0.698 0.120 0.036 0.066 1.079 0.376 0.250 0.099 0.060 0.000 0.060 0.160
3 0.950 0.820 0.610 0.531 0.012 0.017 0.000 0.000 0.062 0.036 0.038 0.781 0.187 0.137 0.541 0.581 0.244 0.152 0.712 0.974 1.194 0.713 0.897 0.150 0.074 0.146
4 1.520 0.930 0.484 1.262 0.307 0.459 0.044 0.059 0.000 1.004 0.091 0.108 0.373 0.472 0.644 0.316 0.394 0.693 0.388 0.797 0.692 1.476 2.627 0.808 0.428 0.220
5 0.720 2.000 0.377 1.293 0.778 1.057 0.240 0.114 0.072 0.105 0.319 0.087 0.085 0.320 0.810 0.179 0.346 0.617 0.798 0.482 0.660 1.020 2.263 1.646 0.648 0.737
2-199
AGE 6 1.200 1.020 0.237 0.541 0.401 1.199 0.529 0.133 0.300 0.073 0.000 0.209 0.111 0.058 0.164 0.312 0.218 0.437 0.713 0.164 0.239 0.401 0.822 1.017 0.809 0.760 7 1.020 0.760 0.609 0.716 0.310 0.908 0.412 0.259 0.379 0.081 0.042 0.033 0.152 0.085 0.027 0.116 0.073 0.084 0.214 0.182 0.253 0.293 0.683 0.869 0.883 0.574
8 0.380 0.670 0.362 0.632 0.202 0.412 0.172 0.185 0.239 0.327 0.009 0.101 0.045 0.000 0.028 0.110 0.000 0.083 0.154 0.031 0.116 0.163 0.351 0.387 0.368 0.383
9 0.400 0.420 0.093 0.475 0.196 0.148 0.194 0.009 0.137 0.081 0.050 0.083 0.149 0.015 0.070 0.042 0.000 0.014 0.076 0.014 0.000 0.113 0.192 0.197 0.158 0.245
10 0.310 0.130 0.259 0.214 0.115 0.149 0.079 0.061 0.086 0.015 0.018 0.138 0.015 0.015 0.008 0.000 0.000 0.000 0.000 0.023 0.035 0.028 0.103 0.046 0.161 0.086
11 0.300 0.200 0.175 0.166 0.173 0.044 0.038 0.023 0.084 0.056 0.009 0.018 0.016 0.000 0.000 0.038 0.032 0.000 0.000 0.000 0.000 0.000 0.014 0.060 0.135 0.018
12 0.120 0.240 0.026 0.075 0.117 0.072 0.063 0.000 0.029 0.056 0.011 0.022 0.046 0.068 0.000 0.028 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
13 0.160 0.220 0.033 0.054 0.023 0.027 0.055 0.000 0.000 0.019 0.000 0.000 0.000 0.000 0.016 0.000 0.000 0.000 0.028 0.000 0.000 0.000 0.029 0.016 0.000 0.021
14+ 1.100 0.900 0.292 0.376 0.266 0.691 0.248 0.163 0.000 0.056 0.030 0.064 0.019 0.037 0.016 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.037 0.009 0.067 0.000
Table G.5. Stratified mean number per tow at age of witch flounder in NEFSC bottom trawl spring and autumn surveys (Strata 22-30, 36-40), 1980 - 2005.
Total 8.460 8.400 3.642 6.407 3.001 5.182 2.073 1.007 1.434 1.945 0.626 1.684 1.260 1.469 3.129 1.883 1.359 2.219 4.274 3.149 3.446 4.409 8.101 5.204 3.799 3.362
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
AUTUMN
0.040 0.030 0.020 0.000 0.000 0.000 0.009 0.000 0.000 0.174 0.481 0.224 0.097 2.541 0.432 0.512 0.232 0.892 0.639 0.323 0.943 0.000 0.000 0.018 0.276
0
0.000 0.070 0.000 0.008 0.000 0.000 0.000 0.000 0.007 0.018 0.088 0.021 0.029 0.672 0.156 0.203 0.092 0.339 0.082 0.521 0.096 0.039 0.000 0.000 0.072
1 0.020 0.030 0.000 0.011 0.000 0.009 0.000 0.023 0.000 0.018 0.137 0.177 0.109 0.154 0.287 0.764 0.261 0.979 0.520 1.178 0.719 0.210 0.275 0.038 0.014
2 0.000 0.240 0.058 0.507 0.093 0.059 0.000 0.000 0.725 0.082 0.380 0.661 0.259 0.544 0.532 1.624 0.785 0.522 1.363 1.514 1.408 0.952 0.431 0.075 0.086
3 0.200 0.440 0.013 1.596 0.943 0.076 0.051 0.011 0.055 0.301 0.507 0.329 0.224 0.777 0.165 0.858 1.988 0.871 0.465 1.044 1.746 3.156 1.475 0.307 0.453
4 0.260 0.610 0.027 0.758 0.991 0.610 0.266 0.023 0.012 0.009 0.219 0.290 0.054 0.219 0.395 0.472 1.386 0.770 0.303 0.600 0.674 1.886 0.997 0.580 0.987
5
7 0.360 0.270 0.241 0.444 0.535 0.482 0.309 0.192 0.215 0.017 0.023 0.067 0.000 0.022 0.106 0.000 0.066 0.329 0.110 0.275 0.229 0.612 0.331 0.315 0.498
2-200
0.280 0.460 0.076 0.548 0.605 0.684 0.353 0.046 0.036 0.021 0.024 0.145 0.061 0.058 0.037 0.229 0.441 0.383 0.165 0.364 0.589 0.813 0.532 0.770 0.826
AGE 6 0.170 0.260 0.132 0.084 0.310 0.270 0.160 0.071 0.048 0.084 0.023 0.059 0.000 0.081 0.000 0.000 0.065 0.000 0.043 0.050 0.152 0.159 0.148 0.129 0.355
8 0.150 0.180 0.015 0.137 0.149 0.103 0.112 0.000 0.046 0.078 0.025 0.030 0.019 0.000 0.043 0.011 0.037 0.000 0.012 0.037 0.049 0.058 0.071 0.222 0.054
9 0.270 0.210 0.027 0.073 0.126 0.122 0.009 0.009 0.045 0.024 0.000 0.052 0.009 0.019 0.009 0.054 0.000 0.000 0.000 0.009 0.000 0.056 0.000 0.083 0.105
10 0.040 0.170 0.032 0.114 0.073 0.029 0.010 0.000 0.079 0.000 0.000 0.028 0.019 0.042 0.000 0.000 0.033 0.000 0.000 0.000 0.000 0.000 0.046 0.021 0.072
11 0.160 0.040 0.009 0.025 0.041 0.015 0.021 0.000 0.011 0.026 0.009 0.000 0.000 0.000 0.005 0.000 0.000 0.020 0.000 0.000 0.026 0.000 0.005 0.046 0.000
12 0.120 0.130 0.039 0.000 0.132 0.089 0.052 0.023 0.043 0.000 0.055 0.000 0.019 0.011 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.019 0.000
13 0.570 0.480 0.301 0.415 0.375 0.217 0.237 0.085 0.055 0.037 0.034 0.000 0.042 0.014 0.042 0.009 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.038 0.019
14+ 2.620 3.660 0.991 4.718 4.373 2.763 1.590 0.482 1.376 0.888 2.005 2.083 0.940 5.154 2.209 4.736 5.384 5.105 3.701 5.915 6.630 7.940 4.311 2.660 3.816
Total
Table G.5. continued. Stratified mean number per tow at age of witch flounder in NEFSC bottom trawl spring and autumn surveys (Strata 22-30, 36-40), 1980-2004.
Table G.6. Parameter estimates (with associated statistics) and estimates of terminal F from ADAPT VPA formulations for witch flounder; stock sizes in >000s. Notes:
SARC 37
Re-Run of SARC 37
Revised CAA (age and length)
GARM 2005 BASE RUN
Software
NFTv2011
NFTv222
NFTv222/231
NFT 231
CAA Est.Ages
1982-2002 3-11+ 3-10
1982-2002 3-11+ 3-10
1982-2002 3-11+ 3-10
1982-2004 3-11+ 3-10
NMFS-s
3-11+
3-11+
3-11+
3-11+
NMFS-a
3-11+
3-11+
3-11+
3-11+
.791
.791
.793
.811
M.S.R. N3 (cv)
19,759 (.64)
19,759 (.64)
19,752 (.64)
3,902 (.65)
N4 (cv)
25,441 (.45)
25,441 (.45)
25,432 (.45)
4,053 (.46)
N5 (cv)
42,739 (.37)
42,739 (.37)
42,727 (.37)
9,206 (.39)
N6 (cv)
41,657 (.33)
41,657 (.33)
41,640 (.33)
14,614 (.35)
N7 (cv)
21,203 (.31)
21,203 (.31)
21,204 (.31)
19,943 (.32)
N8 (cv)
10,370 (.32)
10,370 (.32)
10,362 (.32)
17,315 (.30)
N9 (cv)
3,903 (.33)
3,903 (.33)
3,931 (.33)
8,815 (.27)
791 (.45)
791 (.45)
792 (.45)
2,245 (.37)
N10 (cv) Age 3 in T+1 (>000s)
19,760
19,760
19,752
3,902
F1
-
-
-
-
F2
-
-
-
-
F3
0.0015
0.0015
0.0015
0.0058
F4
0.0161
0.0161
0.0160
0.0323
F5
0.0268
0.0268
0.0269
0.0661
F6
0.0595
0.0595
0.0591
0.0690
F7
0.1741
0.1741
0.1748
0.0772
F8
0.2648
0.2648
0.2622
0.1136
F9
0.5526
0.5526
0.5570
0.2838
F10
0.4087
0.4087
0.4096
0.1987
F11+
0.4087
0.4087
0.4096
0.1987
Ave F 7-9
-
-
-
-
Ave F 8-9
0.4087
0.4087
0.4096
0.1987
SSB (>000 mt)
18,296
18,369
18,370
21,175
2-201
Total
Age
Total
Age
3 4 5 6 7 8 9 10 11+
3 4 5 6 7 8 9 10 11+
Table G.7.
14268 7999 8658 3022 1651 454 1322 274 783 38431
1994
15405 12175 9563 7830 4289 2752 2102 1101 7260 62477
1982
12680 12242 5958 4908 1416 662 210 642 373 39091
1995
17701 13082 9493 7114 5375 3077 1763 1440 4728 63773
1983
18854 10332 10193 4166 2644 440 323 91 181 47224
1996
16343 14923 10014 6765 4668 3160 1746 839 3844 62302
1984
19931 16114 8407 7656 2329 964 137 81 114 55733
1997
7652 13931 11487 6769 4217 2647 1344 862 2926 51835
1985
19769 17029 12890 6296 5394 1067 286 41 185 62957
1998
5417 6471 10901 7929 4039 2224 1132 599 2040 40752
1986
2-202
32280 16708 14141 10109 4111 3156 576 116 200 81397
1999
3002 4641 5221 7980 4267 2034 1146 594 1151 30036
1987
44865 27634 13893 11157 7349 2431 2010 264 665 110268
2000
9745 2563 3827 4061 5685 2222 950 544 1218 30815
1988
41852 38520 23519 11540 8521 4765 1164 1215 880 131976
2001
6215 7831 2077 3049 2887 3616 854 448 1263 28240
1989
25021 35957 32836 19374 8925 5749 2759 422 895 131938
2002
6673 4935 6336 1727 2333 1784 2298 413 900 27399
1990
12889 21498 30258 27126 15384 5704 3769 1781 1427 119836
2003
8835 5425 3661 4434 1250 1755 1100 1669 1372 29501
1991
Estimates of beginning year stock size (thousands of fish), instantaneous fishing mortality and spawning stock biomass (mt) for witch flounder estimated from virtual population analysis, 1982-2004.
4737 11047 18141 24831 21733 11474 3465 2551 1738 99717
2004
14374 7195 4294 2354 3284 858 1284 677 2128 36448
1992
3902 4054 9207 14615 19948 17316 8815 2245 3027 83129
2005
9743 12002 5032 2902 1164 2164 552 941 1319 35819
1993
Age
Age
3 4 5 6 7 8 9 10 11+
3 4 5 6 7 8 9 10 11+
Fishing Mortality
1994 0.003 0.145 0.418 0.608 0.764 0.622 0.573 0.585 0.585
1982 0.013 0.099 0.146 0.226 0.182 0.295 0.228 0.266 0.266
Table G.7. continued.
1995 0.055 0.033 0.208 0.468 1.020 0.569 0.686 0.596 0.596
1983 0.021 0.117 0.189 0.271 0.381 0.416 0.593 0.477 0.477
1996 0.007 0.056 0.136 0.431 0.859 1.013 1.234 1.100 1.100
1984 0.010 0.112 0.242 0.323 0.417 0.705 0.556 0.650 0.650
1997 0.007 0.073 0.139 0.200 0.630 1.064 1.063 1.064 1.064
1985 0.018 0.095 0.221 0.366 0.490 0.700 0.657 0.685 0.685
1998 0.018 0.036 0.093 0.276 0.386 0.466 0.754 0.520 0.520
1986 0.005 0.065 0.162 0.470 0.536 0.514 0.495 0.507 0.507
2-203
1999 0.005 0.034 0.087 0.169 0.376 0.301 0.631 0.346 0.346
1987 0.008 0.043 0.101 0.189 0.502 0.612 0.595 0.606 0.606
2000 0.002 0.011 0.036 0.120 0.283 0.587 0.353 0.474 0.474
1988 0.069 0.061 0.077 0.191 0.302 0.807 0.601 0.741 0.741
2001 0.002 0.010 0.044 0.107 0.244 0.396 0.865 0.473 0.473
1989 0.081 0.062 0.034 0.117 0.331 0.303 0.576 0.350 0.350
2002 0.002 0.023 0.041 0.081 0.298 0.272 0.288 0.277 0.277
1990 0.057 0.149 0.207 0.173 0.135 0.333 0.170 0.238 0.238
2003 0.004 0.020 0.048 0.072 0.143 0.349 0.240 0.304 0.304
1991 0.055 0.084 0.292 0.150 0.226 0.162 0.335 0.225 0.225
2004 0.006 0.032 0.066 0.069 0.077 0.114 0.284 0.199 0.199
1992 0.030 0.208 0.242 0.554 0.267 0.291 0.161 0.211 0.211
1993 0.047 0.177 0.360 0.414 0.792 0.343 0.551 0.382 0.382
1982 20 107 376 1115 1543 1634 1632 949 9521 16898
1994 26 156 637 630 585 231 864 217 876
4222
Age 3 4 5 6 7 8 9 10 11+ Total
Age 3 4 5 6 7 8 9 10 11+
Total
3946
1995 11 162 606 1205 543 353 145 510 410
1983 21 132 458 1241 1883 1544 1172 1207 5781 13439
Spawning Stock Biomass (mt)
Table G.7 continued.
3899
1996 12 113 896 1153 1053 226 197 70 181
1984 39 185 580 1243 1715 1559 1088 628 4505 11542
4209
1997 9 115 599 1845 906 464 88 62 120
1985 8 127 684 1584 1720 1388 878 666 3374 10428
2-204
5489
1998 31 247 1069 1305 1921 502 180 34 200
1986 6 91 1020 1916 1636 1218 780 487 2414 9569
6995
1999 62 300 1096 2072 1407 1499 303 95 160
1987 18 216 881 2472 1794 1072 757 479 1323 9012
8903
2000 106 464 1081 2059 2359 1048 1082 156 549
1988 69 191 746 1298 2495 1148 628 422 1392 8389
11132
2001 161 646 1782 2047 2605 1977 559 689 666
1989 71 238 360 965 1303 2010 559 367 1578 7451
14177
2002 135 681 2252 3376 2708 2468 1489 283 783
1990 18 156 587 454 999 1003 1641 358 1227 6444
18349
2003 29 412 2230 4526 4771 2358 1914 1039 1070
1991 19 104 336 887 496 1004 754 1411 1830 6842
21175
2004 21 205 1204 4003 6278 4811 1734 1490 1429
1992 62 145 464 582 1370 500 917 548 2491 7079
1993 36 230 437 695 424 1211 393 789 1612 5827
Year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Median
1645 6759 3340.087
Catch (mt) 4954 6159 6759 6192 4636 3494 3320 2199 1645 1870 2395 2973 3073 2386 2338 2065 2124 2327 2550 3241 3467 3506 3149
3901 21175 9365.6957
SSB (mt) 16897 13439 11542 10429 9568 9012 8389 7451 6443 6841 7079 5827 4222 3945 3901 4208 5489 6994 8904 11132 14175 18349 21175
2-205
0.199 1.123 0.516
Ave F 8-9 0.262 0.505 0.631 0.679 0.504 0.603 0.704 0.440 0.251 0.249 0.226 0.447 0.597 0.627 1.123 1.063 0.610 0.466 0.470 0.631 0.280 0.294 0.199
14.268
3.002 44.865 15.506 12.266
Recruits Age 3 15.405 17.701 16.343 7.652 5.417 3.002 9.745 6.215 6.673 8.835 14.374 9.743 14.268 12.680 18.854 19.931 19.769 32.280 44.865 41.852 25.021 12.889 4.737 3.902 Year Class 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Summary of witch flounder catch (mt), spawning stock biomass (mt), fully recruited fishing mortality, recruitment (age 3, thousands of fish) and the year class.
min max mean Geomean
Table G.8.
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
Year
Figure G.1. Historical 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 northern shrimp and large-mesh otter trawl fisheries.
2-206
TOTAL CATCH ('000 of fish) AT AGE 2500 2000
2000
1982
1500
1500 1000
1000
500
500
0 2000
0
1983
1500
1500 1000
1000
500
500
0 2000
1500
Numbers of fish ('000)
1000
1000
500
500
0
1500
500
500 0
0
1986
2500 2000 1500 1000
1500 1000 500
0
1987
1500
1500 1000
1000
500
500
0
1995
0
1988
1500
1500 1000
1000
500
500
0 2000
1994
500
0
2000
1993
1000
1000
2000
1992
0
1985
1500
2500 2000
1991
0
1984
1500
2000
1990
1996
0
1989
1500
1997
1500 1000
1000
500
500 0 0
1
2
3
4
5
6
7
8
9
10 11+
Age
0 0
1
2
3
4
5
6
7
8
9
10 11+
Age DISCARDS IN SHRIMP FISHERY DISCARDS IN L-M OTTER TRAWL LANDINGS
Figure G.2. Number of witch flounder (‘000 of fish) at age in the total catch, by fishery, 1982-2004. Open bar represents discards in the shrimp fishery, diagonal bar represents discards in large-mesh fishery and hatched bar represents landings.
2-207
TOTAL CATCH ('000 of fish) AT AGE 2000 1500
1998
1000 500 0 1500
1999
1000 500 0 1500
2000
Numbers of fish ('000)
1000 500 0 2000
2001
1500 1000 500 0 2000
2002
1500 1000 500 0 1500
2003
1000 500 0 1500
2004
1000 500 0
0
1
2
3
4
5
6
7
8
9 10 11+
Age
DISCARDS IN SHRIMP FISHERY DISCARDS IN L-M OTTER TRAWL FISHERY LANDINGS
Figure G.2 continued.
2-208
0.8
Mean weight (kg) at age
0.7
0.6
Age 8 0.5
Age 7 0.4
Age 6 0.3
Age 5 Age 4
0.2
0.1 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008
Year Figure G.3. Witch flounder mean weights at age in the catch, 1982 – 2004.
2-209
7
Mean weight (kg) per tow
6
A Spring
5
4
3
2
1
Autumn 0 1963
1967
1971
1975
1979
1983
1987
1991
1995
1999
2003
1991
1995
1999
2003
Year 10
B Spring
Mean number per tow
8
6
4
2
Autumn 0 1963
1967
1971
1975
1979
1983
1987
Year Figure G.4. Stratified mean weight (kg) per tow (A) and mean number per tow (B) of witch flounder in the NEFSC spring and autumn bottom trawl surveys, 1963-2005.
2-210
1.2
Catch
F
1.0
Catch (000's mt)
5 0.8 4 0.6 3 0.4
2
0.2
1 0
0.0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004
Year Figure G.5. Trends in total catch and fishing mortality for witch flounder, 1982-2004.
2-211
Average F (ages 8-9,u)
6
30
Recruits SSB
25 20
40 15 10
20
5 0
0 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005
Recruitment Year class, SSB Year Figure G.6. Trends in spawning stock biomass and recruitment (age 3) for witch flounder; 1982 – 2004.
2-212
Biomass (000's mt)
Recruits (Age 3, millions)
60
Average F (ages 8-9)
3.0
A
2.5 2.0 1.5 1.0 0.5 0.0
SSB (000's mt)
1982
24 22 20 18 16 14 12 10 8 6 4 2
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
B
1982
1984
Age 3 Recruitment (000's)
140 120
C
100 80 60 40 20 0 1982
1984
Figure G.7. Retrospective analysis results of fishing mortality(A), spawning stock biomass (B), and age 3 recruitment (C) for witch flounder.
2-213
50
Spawning Stock Biomass ('000 mt)
A 45
40 A13 projected
35
30
25
20
15 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year 0.45
B 0.40
Fishing Mortality
A13 projected 0.35
0.30
0.25
0.20
0.15 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year Figure G.8 . Comparisons of Amendment 13 projected and 2004 assessment estimates of witch flounder spawning stock biomass (A) and fishing mortality (B), 2003 - 2014. Solid lines represent the median values and dash lines represent the 25 and 75 percentiles.
2-214
near zero. This is attributed to the short northern shrimp season and the shift in effort to nearshore waters, inshore of the witch flounder distribution Witch flounder discarded in the northern shrimp fishery range in age from 0 to 6, with the majority at ages 1-3. The number of fish discarded in the shrimp fishery is small compare to the landings (Figure G.2). The estimation of large-mesh otter trawl discards is based upon two methods. For 1982 to 1994, a method which filters survey length frequency data through a commercial gear retention ogive and a culling ogive was used and then a semi-annual ratio estimator of survey-filtered ‘kept’ index to semi-annual numbers landed was used to expand the estimated ‘discard’ survey index to numbers of fish discarded at length. For 1989 to 2004, discard weight to kept weight ratios (d/k) were calculated from observer data on a semi-annual basis. Total discard weight was derived by multiplying the d/k ratio by the commercial landings. Given the limited sample size (number of trips) prior to 1995, discards at age were estimated from 1995 onward. Observed discard length frequencies are used to estimate discarded fish at length. Semi-annual numbers of fished discarded were apportioned to age using the corresponding seasonal NEFSC survey age/length key. Witch flounder discarded in the large mesh otter trawl fishery range in age from 0 to 6, with the majority at ages 4 to 5. The number of fish discarded in the large-mesh otter trawl fishery is small compare to the landings (Figure G.2). The total catch (landings + otter trawl discards + shrimp trawl discards) at age is presented in Table G.3 and Figure G.2. The age composition data reveal strong 1979- 1981 year classes; the 1989 and 1993 year classes also appear strong. The poor 1984 year class is also evident as well as a truncated age-structure since the early 1990’s. As observed in recent years, the mean weights-at-age in the catch continue to decline (Figure G.3). Research Vessel Survey Indices The NEFSC bottom trawl survey indices generally declined from the early 1960s to record low levels in the late 1980s and early 1990s. Since then survey indices increased but have exhibited a declining trend since 2000 (Table G.4, Figure G.4a-b). Survey age compositions (mean number per tow at age)are presented in Table G.5. The survey mean weights and mean lengths at age show a similar decline as reported in the commercial landings. Survey maturity-at-age has remained stable in recent years. 3.0 Assessment Results Since the last assessment, minor VPA software changes have occurred and additional age and length data have become available. These changes had only a minor impact on the SARC 37 assessment results (Table G.6). For the current assessment, the VPA formulation is the same as the 2003 assessment and uses catch (landings and discards) through 2004 and NEFSC spring and autumn survey indices through 2005 and 2004, respectively, to estimate stock sizes for ages 3 to 10. The VPA had a mean square residual of 0.81, the coefficients of variation (CVs) for estimated ages ranged between 27% and 65% (Table G.6), and the CVs for survey catchability coeffiecients (q) were consistent, ranging from 11% to 25%.
2-186
VPA results indicate average fishing mortality (ages 8-9, unweighted) increased from 0.26 in 1982 to 0.68 in 1985, declined to 0.22 in 1992, increased to 1.12 in 1996, then declined to 0.20 in 2004 (Tables G.7 and G.8, Figure G.5). Spawning stock biomass declined steadily from 16,897 mt in 1982 to 3,901 mt in 1996, and has increased to21,175 mt in 2004 (Tables G.7 and G.8, Figure G.6). Since 1982, recruitment at age 3 has ranged from approximately 3 million fish (1984 year class) to 45 million fish (1997 year class) with a mean of 15.5 million fish (median of 14 million; Table G.7, Figure G.6). The addition of the 2000 to 2002 year classes to the stockrecruit data continued the negative trend observed in this relationship in the previous assessment. The current age composition of the spawning stock is approaching the equilibrium age composition. However, given the recent poor year classes (2000-2002), spawning stock biomass will eventually decline as these poor classes enter the fishery (Figure G.6). The retrospective analysis indicates that average F was underestimated in the late 1990s and early 2000s (Figure G.7a) and spawning stock biomass was consistently overestimated (Figure G.7b). The retrospective analysis indicated a pattern of relatively consistent estimates of the number of age 3 recruits, with the notable exception of the 1992, 1993 and 1996 year classes, which were considerably overestimated (Figure G.7c). Bootstrap results suggest that the estimates of F and spawning stock biomass are relatively precise with CVs of 30% and 14%, respectively. The 80% confidence interval for F2004=0.20 was 0.15 and 0.28, and for SSB2004 = 21,175 mt the 80% confidence interval was 18,192 mt and 26,121 mt.
4.0 Biological Reference Points Based on yield and spawning stock biomass per recruit analyses and the arithmetic mean of the VPA age 3 recruitment (NEFSC 2003), the biological reference points are: SSBmsy = 25,248 mt Fmsy = F40% = 0.23 MSY = 4,375 mt. The 2004 spawning stock biomass (21,175 mt) was above ½ SSBmsy (12,624 mt), the overfished threshold, and 2004 fishing mortality (0.20) was below Fmsy (0.23), the overfishing threshold; therefore, witch flounder was not overfished and overfishing was not occurring in 2004. Amendment 13 Projections and current status There is no formal rebuilding program required for witch flounder, thus there is not a rebuilding biomass trajectory. Amendment 13 is designed to end overfishing of witch flounder; a spawning stock biomass trajectory at Fmsy was conducted for Amendment 13. The spawning stock biomass estimates from this assessment are below what was projected for the Amendment 13. The fishing mortality estimated for 2004 is below the Fmsy used in the Amendment 13 projections (Figure G.8).
2-187
5.0 Panel Comments The Panel discussed the adequacy of the age-length information used to estimate the commercial landings-at-age. There is now sufficient information for some of the years to develop estimates by quarter and market category, and given continued adequate sampling, this should be continued in the future. This may be important as the fishery has apparently shifted from peewees and smalls to smalls and mediums. There is some caution about simply using the number of samples as an indication about sample size. In the past, a sample normally consisted of about 100 fish. With potentially smaller catches, this criterion for sampling has been relaxed in order to get samples. Given that witch flounder is very slow growing, the pooling effect may not be as much of an issue. There was some discussion of the apparent expansion in age structure of the discards beginning in 1995. It was suggested that this may be an artifact of the change in estimation method beginning in 1995. However, another expansion of the age structure was apparent in 2002 with the same method. Observed discards of large fish may be due to the inclusion of trips from other fisheries that do not require use of a DAS, although trips targeting Loligo were excluded. The panel discussed the recent declines in mean weights. It is possible that fishing patterns have changed in relation to the distribution of the stock to areas that are less favorable for growth. The distribution of the fishery and survey should be investigated in the future. The short term decline in size at maturity in the late 1980s was discussed. This short term decline coincided with very low biomass. It was not possible to examine the decline on an annual basis due to low sampling (sparse data). The difference in current estimate of 2004 biomass compared to the estimate projected from the last assessment may be due to an increase in the estimate of realized F being higher than that used in the projections, lower recruitment than expected and a retrospective underestimate of SSB. The Panel noted that the recent increase in SSB has been mostly driven by the good recruitment of the 1996-1998 year classes. If catches remain constant, SSB will eventually decline as the following poor year classes enter the fishery. Projection Advice - The Panel recommended using an average of the mean weights from 20022004 for projections. The same years are suggested for the partial recruitment and maturity (5 year average of 2001-2005) vectors. Given the declining trend in recruitment, the panel recommended using the estimated value of the 2002 year class although it was an uncertain estimate. For 2006-2008, the panel suggested re-sampling just the 2000-2002 year classes (not the entire series). Given that witch flounder is long-lived and late maturing, the values of recruitment should not be influential in the projections. 6.0 Sources of Uncertainty &
Low frequency of samples across market category and quarter results in imprecise mean
2-188
weights at age and estimates of numbers at age. &
Lack of data to support direct estimates of discards at age requires use of various surrogate survey-based methods.
&
Retrospective patterns suggest that estimates of SSB may be overestimated (e.g. future assessments may have lower estimates of SSB).
&
The research bottom trawl survey catches very few witch flounder; in most years, the stratified mean number per tow of witch flounder is less than 5 fish. Abundance of witch flounder in the late 1980s and early 1990's may have gone below levels that provide reliable estimates of trends in abundance and biomass
7.0 Acknowledgments We thank all those who diligently collected data from the commercial fisheries (dock-side and at-sea) and the research vessel surveys. We thank J. Burnett for providing the age determinations used in the assessment. We thank all the members of the Groundfish Assessment Review Meeting for their review and helpful comments. 8.0 References Burnett, J. and S.H. Clark. 1983. Status of witch flounder in the Gulf of Maine – 1983. NMFS/NEFC, Woods Hole Laboratory Ref. Doc. No. 83-36, 31 p. Lange, A.M.T. and F.E. Lux. 1978. Review of the other flounder stocks (winter flounder, American plaice, witch flounder, and windowpane flounder) off the northeast United States. NMFS, NEFC, Woods Hole Lab. Ref. Doc. No. 78-44, 53 pp. NEFSC [Northeast Fisheries Science Center]. 2003. Report of the 37th Northeast Regional Stock Assessment Workshop (37th SAW), Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. Doc. 03-16, 597 p. Wigley, S.E., J. K.T. Brodziak, and L. Col. 2003. Assessment of the Gulf of Maine and Georges Bank witch flounder stock for 2003. Northeast Fish. Sci. Cent. Ref. Doc. 03-14, 186 p.
2-189
Table G.1. Witch flounder landings, discards and catch (metric tons, live) by country, 1937-2004 [1937-1959 provisional landings reported in Lange and Lux, 1978; 1960-1963 reported to ICNAF/NAFO (Burnett and Clark, 1983)].
LANDINGS Year
1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981
USA Subarea 4, 5 & 6
1255 1022 976 1226 1381 2140 2935 3370 2807 2542 3112 3220 2934 2523 1839 2127 1871 2469 3501 2878 3128 3442
USA Subarea 3
USA Total 5000 3600 3100 3000 2000 1800 1000 1000 1000 1500 1500 1000 3600 3000 2600 3700 4200 4000 2400 2000 1000 1000 1000 1255 1022 976 1226 1381 2140 2935 3370 2807 2542 3112 3220 2934 2523 1839 2127 1871 2469 3501 2878 3128 3442
2-190
CAN
2 1 27 37 22 68 63 56 19 35 13 10 9 13 5 11 18 17 18 7
Other
121 502 311 249 191 1310 130 2860 2568 629 292 217 6 13 6 1
Total 5000 3600 3100 3000 2000 1800 1000 1000 1000 1500 1500 1000 3600 3000 2600 3700 4200 4000 2400 2000 1000 1000 1000 1255 1024 977 1374 1418 2664 3314 3682 3054 3852 3261 6115 5515 3162 2140 2357 1882 2493 3525 2895 3147 3449
USA Discards
USA Catch
Table G.1. continued. Witch flounder landings, discards and catch (metric tons, live).
LANDINGS Year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
USA Subarea 4, 5 & 6 4906 6000 6660 6130 4610 3450 3262 2068 1465 1777 2227 2601 2665 2209 2087 1771 1848 2121 2439 3019 3188 3124 2917
USA Subarea 3
255 539 346 358 297 2
USA Total 4906 6000 6660 6385 5149 3796 3620 2365 1467 1777 2227 2601 2665 2209 2087 1771 1848 2121 2439 3019 3188 3124 2917
2-191
CAN 9 45 15 46 67 23 45 13 12 7 7 10 34 11 10 7 10 19 53 32 34 30
Other
Total 4915 6045 6675 6431 5216 3819 3665 2378 1479 1784 2234 2611 2699 2220 2097 1778 1858 2140 2492 3051 3222 3154 2917
USA Discards 48 162 100 61 25 47 60 133 184 95 171 376 422 193 254 300 286 213 115 224 279 381 233
USA Catch 4954 6162 6760 6191 4635 3497 3322 2201 1649 1872 2398 2977 3087 2402 2341 2071 2134 2334 2554 3243 3467 3505 3150
348 5 527 128
475 5 680 135
462 5 804 154
465 12 1530 319
384 6 662 123
1982 mt n len age
1983 mt n len age
1984 mt n len age
1985 mt n len age
1986 mt n len age
Year 1981 mt n len age
309 3 307 60
377 1 105 29
322 9 1112 250
250 2 232 30
1 2 194 55
Quarter 1 Small Med. 260 7 . . . . . .
356 5 515 89
613 2 229 50
1036 4 400 76
910 3 265 55
726 6 626 150
Large 517 . . .
654 5 558 106
697 5 657 106
513 7 970 186
471 5 685 131
342 1 126 30
421 4 410 97
453 4 426 77
393 1 117 25
286 1 96 16
73 2 209 55
Quarter 2 Small Med. 269 32 . 1 . 101 . .
595 5 413 129
850 7 698 153
1000 7 775 180
1037 5 520 125
886 2 216 50
Large 694 1 103 26
2-192
375 4 302 63
526 7 795 97
403 8 1045 210
298 8 1008 152
287 2 189 50
238 3 364 75
291 7 800 138
248 1 106 28
154 3 123 0
170 2 210 50
Quarter 3 Small Med. 242 13 . 1 . 89 . 25
354 4 406 100
553 6 684 113
653 2 191 53
758 8 981 159
739 6 514 150
Large 607 . . .
312 5 416 87
433 8 824 161
429 4 615 105
257 6 677 180
278 3 307 81
212 3 337 75
310 2 264 25
286 2 243 44
169 3 344 75
201 4 393 105
Quarter 4 Small Med. 230 0 1 . 105 . 25 .
238 2 233 52
408 4 349 29
586 1 91 25
613 . . .
669 2 189 50
Large 453 1 100 25
4448 49 4923 1056
5976 65 7361 1297
6331 51 6469 1336
5678 49 5611 1058
4720 37 3700 954
90
92
124
116
128
Sampling All Ratio 3324 5 498 101
Table G.2. Summary of USA commercial witch flounder landings (mt), number of length samples (n), number of fish measured (len) and number of age samples (age) by market category and quarter for all gear types, 1981 - 2004. The sampling ratio represents the amount of landings per length sample.
424 5 335 70
230 1 94 25
113 1 134 15
71 5 262 53
180 4 259 42
1988 mt n len age
1989 mt n len age
1990 mt n len age
1991 mt n len age
1992 mt n len age
86 2 241 46
56 2 224 50
125 2 199 40
174 2 201 50
304 4 407 89
Table G.2. continued. Quarter 1 Year Small Med. 1987 mt 349 211 n 1 1 len 85 145 age 25 25
82 2 185 52
58 3 401 80
107 3 199 45
148 2 222 49
271 5 465 106
Large 228 2 200 50
466 7 501 78
219 7 537 93
147 6 335 81
255 2 230 50
436 5 344 71
Small 432 4 323 77
163 1 125 25
151 2 239 45
168 3 296 70
264 2 236 46
393 5 544 110
Quarter 2 Med. 317 2 228 47
174 2 235 25
167 1 125 25
147 1 100 25
251 1 27 25
389 3 429 77
Large 387 3 316 76
2-193
205 7 477 86
192 4 212 49
100 6 349 69
98 2 150 40
184 5 396 70
Small 296 5 354 78
115 1 121 25
142 2 165 49
119 2 247 41
145 2 206 51
176 4 359 100
Quarter 3 Med. 203 5 583 113
138 1 117 25
184 3 249 52
129 2 145 50
156 1 100 25
208 3 295 75
Large 247 4 400 95
212 2 129 27
168 5 300 66
84 7 381 103
85 1 125 25
140 3 229 61
Small 298 2 204 48
97 . . .
108 4 410 97
79 2 201 48
107 2 202 47
140 4 402 95
Quarter 4 Med. 203 3 261 64
116 1 46 23
121 3 274 58
85 . . .
103 . . .
131 3 356 69
Large 202 2 178 51
2034 30 2436 454
1637 41 3398 717
1403 35 2586 587
2016 18 1793 433
3196 49 4561 993
All 3373 34 3277 749
68
40
40
112
65
69
Sampling Ratio
Small 350 7 830 55
403 . . .
336 3 208 53 313 5 504 59
313 6 557 77
372 5 339 45
386 3 282 15
Year 1993 mt n len age
1994 mt n len age
1995 mt n len age 1996 mt n len age
1997 mt n len age
1998 mt n len age
1999 mt n len age
Table G.2.
48 . . .
39 2 206 50
40 3 350 68
91 3 348 84 57 2 218 45
143 . . .
Quarter 1 Med. 112 1 100 25
19 . . .
19 1 128 19
25 3 351 70
77 3 347 89 36 3 292 78
98 . . .
Large 110 . . .
616 4 308 62
587 4 238 30
478 9 812 108
586 6 459 81 545 5 331 53
505 3 560 59
Small 442 7 741 56
79 . . .
79 1 88 .
86 4 418 73
117 3 367 75 86 2 240 50
183 5 532 104
Quarter 2 Med. 192 1 107 27
31 . . .
31 1 135 29
41 3 309 77
100 5 517 135 60 1 127 26
154 6 749 134
Large 161 1 100 26
2-194
436 17 1110 143
380 5 484 47
398 9 783 98
399 . . . 458 5 494 59
390 5 356 44
Small 263 9 728 74
67 2 201 .
40 3 186 22
55 3 308 81
61 . . . 56 4 464 86
122 5 648 113
Quarter 3 Med. 122 1 85 .
30 3 306 32
20 1 100 .
27 1 107 20
70 . . . 44 4 468 101
117 1 105 26
Large 150 5 499 73
353 11 775 91
239 . . .
265 9 505 73
304 2 217 27 363 5 343 60
383 5 342 56
Small 331 . . .
38 1 109 16
26 . . .
31 1 128 18
48 . . . 42 3 277 70
91 3 368 60
Quarter 4 Med. 96 . . .
18 . . .
14 . . .
16 1 50 23
40 1 94 25 28 3 348 69
80 4 407 82
Large 106 . . .
2121 41 3091 359
1849 23 1904 242
1775 52 4678 786
2212 26 2557 569 2088 42 4106 756
2670 37 4067 678
All 2435 32 3190 336
51
80
34
50
85
72
76
Sampling Ratio
603 4 324 57
609 5 480 73
2004 mt n len age
740 5 363 75
2002 mt n len age
2003 mt n len age
583 8 744 125
2001 mt n len age
Year 2000 mt n len age
76 13 1244 226
70 6 423 93
79 1 121 16
71 4 422 64
Quarter 1 Small Med. 477 53 31 2 2253 91 393 10
Table G.2. continued.
16 23 1813 505
17 6 162 60
18 2 107 50
17 2 134 42
Large 17 . . .
598 8 675 151
684 10 881 131
774 3 212 65
824 3 237 48
90 5 549 96
108 5 482 64
103 5 518 73
99 3 352 48
Quarter 2 Small Med. 583 93 47 . 2445 . 463 .
23 8 576 169
30 10 433 174
26 3 209 64
30 2 159 64
Large 27 . . .
2-195
758 5 541 58
865 11 943 172
849 5 389 88
699 8 594 126
113 5 356 95
125 6 531 91
114 2 150 34
98 2 209 34
Quarter 3 Small Med. 555 89 17 1 994 105 224 20
30 2 48 10
36 16 552 246
29 3 194 62
28 3 213 46
Large 28 . . .
546 19 1838 49
533 7 654 99
400 3 262 49
507 5 313 61
45 5 420 72
43 7 632 120
45 2 226 30
50 3 232 49
Quarter 4 Small Med. 451 50 5 5 308 558 67 92
13 15 83 .
10 13 525 191
9 2 115 49
13 . . .
Large 16 2 217 51
2917 113 8623 1504
3124 101 6542 1498
3186 35 2815 655
3019 43 3609 707
26
31
89
70
Sampling All Ratio 2439 21 110 6971 1320
Table G.3.
0
0.03 0.00 0.00 0.00 0.00 2.08 0.42 0.85 1.46 3.06 2.84
113.76 8.06 2.68 5.21 8.68
49.78
32.11
21.61
12.33 2.32 0.00 0.00
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
0.00
2.40
20.24
96.96
169.95
252.94
392.89
74.91
32.68
49.95
1368.48
85.80
44.35
17.90
6.29
10.69
14.66
18.92
0.53
0.34
0.33
0.02
0.06
1
7.41
11.21
17.42
66.42
119.51
194.45
294.20
102.92
50.83
655.51
496.44
129.59
159.43
23.26
95.30
50.32
130.29
79.93
3.86
3.47
0.88
4.28
1.72
2
4
6
7
25.36
50.07
40.96
69.93
103.50
160.92
331.23
135.29
121.89
628.79
41.97
417.23
399.46
441.77
343.93
447.05
600.27
22.25
22.95
123.58
146.61
337.11
190.49
2-196
325.78
391.72
744.95
343.22
286.46
526.08
556.89
1058.45
524.44
370.28
1001.80
1807.30
1255.56
405.76
634.14
436.25
139.91
181.26
377.07
1176.12
1466.31
1346.17
1064.47
1078.47
1308.71
1226.69
938.11
451.20
1095.77
1063.74
1015.95
1207.69
1041.23
2759.91
1418.95
859.20
863.74
1103.15
65.16
264.30
467.06
1516.79
2118.21
2002.70
1520.76
1207.67
1538.12
1743.54
1394.91
1088.86
1168.80
1461.98
1415.46
1293.41
1362.86
1714.50
1287.99
918.12
935.96
575.43
255.61
314.33
658.27
1280.06
2775.35
1936.24
1739.59
1575.12
1475.40
1500.94
1909.68
2141.29
1715.57
1689.67
1201.10
1611.62
1019.07
1430.48
851.35
826.85
597.19
716.98
235.77
273.86
759.35
1382.70
1574.70
1566.90
1524.90
1486.50
1590.20
665.20
USA Commercial Catch in Numbers (1000's) at Age
3
AGE 5
1146.27
1565.83
1276.60
1455.26
1009.04
765.34
371.44
593.77
263.23
268.54
196.69
585.56
201.64
244.55
471.07
882.12
1154.10
870.90
834.90
1247.90
1497.50
977.80
656.00
8
797.89
749.60
642.49
632.43
558.09
252.52
142.05
84.55
215.48
97.53
539.15
218.77
177.88
292.11
333.93
349.65
401.50
480.60
412.70
606.00
696.70
737.70
399.50
9
324.36
435.29
95.14
427.38
93.13
31.57
15.54
49.79
57.05
269.49
113.49
278.53
120.04
313.56
81.35
123.39
266.70
252.40
222.80
400.40
375.10
510.40
239.40
10
291.65
348.74
201.85
309.51
234.60
54.36
70.30
70.08
113.62
156.84
324.29
390.48
377.01
257.77
177.49
348.00
597.50
489.40
758.20
1359.20
1718.80
1675.50
1578.40
11+
Total USA commercial catch [landings + shrimp trawl discards + large-mesh otter trawl discards using survey filter and FOP] in numbers, (thousands of fish), mean weight (kg) and mean length (cm) at age of witch flounder, 1982 - 2004.
0.015
0.006
0.004
0.009
0.004
0.004
0.003
0.003
0.005
0.005
0.004
0.004
0.003
0.003
0.003
0.003
0.003
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
1982-2004 2000-2004
Mean
2004
0.004 0.003
0.017
1986
2003
0.017
1985
0.010 0.007
0.008
0.007
0.006
0.006
0.006
0.006
0.023
0.019
0.007
0.004
0.009
0.007
0.014
0.012
0.012
0.006
0.017
1984
0.002 0.009
0.000
0.030 0.034
0.053
0.039
0.032
0.023
0.024
0.024
0.024
0.033
0.031
0.024
0.019
0.027
0.026
0.035
0.029
0.034
0.017
0.033
0.026
0.023
0.040
0.038
0.038
0.091 0.086
0.098
0.070
0.110
0.089
0.066
0.068
0.070
0.070
0.060
0.051
0.070
0.122
0.103
0.062
0.062
0.122
0.045
0.081
0.089
0.128
0.151
0.149
0.152
2-197
0.198 0.196
0.232
0.157
0.219
0.176
0.196
0.217
0.163
0.189
0.149
0.158
0.202
0.202
0.230
0.199
0.186
0.170
0.203
0.191
0.206
0.237
0.229
0.202
0.242
0.295 0.265
0.277
0.243
0.279
0.256
0.272
0.291
0.260
0.274
0.265
0.328
0.280
0.318
0.379
0.344
0.257
0.321
0.311
0.298
0.299
0.305
0.328
0.270
0.329
0.406 0.357
0.342
0.320
0.395
0.362
0.368
0.400
0.359
0.376
0.422
0.435
0.430
0.432
0.459
0.420
0.438
0.425
0.434
0.433
0.408
0.429
0.421
0.409
0.421
0.526 0.450
0.440
0.420
0.474
0.464
0.453
0.514
0.487
0.495
0.554
0.561
0.534
0.535
0.614
0.578
0.586
0.574
0.538
0.561
0.533
0.565
0.539
0.518
0.550
USA Commerical Catch Mean Weight (kg) at Age
0.642 0.536
0.540
0.503
0.552
0.550
0.534
0.584
0.584
0.627
0.708
0.690
0.691
0.666
0.739
0.702
0.688
0.682
0.668
0.686
0.676
0.691
0.664
0.613
0.727
Total USA commercial catch (landings + shrimp trawl discards + LM otter trawl discards). Age 0 1 2 3 4 5 6 7 8
1983
1982
Year
Table G.3. continued.
0.787 0.619
0.612
0.565
0.652
0.645
0.624
0.627
0.869
0.868
0.856
0.910
0.832
0.882
0.822
0.836
0.849
0.818
0.819
0.828
0.853
0.842
0.817
0.795
0.886
9
0.911 0.697
0.692
0.620
0.823
0.647
0.704
0.917
0.978
1.037
0.974
0.974
0.909
1.023
0.882
0.974
1.049
0.968
0.980
0.980
0.975
0.964
0.922
0.977
0.983
10
1.203 0.875
0.871
0.809
0.940
0.840
0.915
0.872
1.206
1.293
1.232
1.243
1.266
1.335
1.243
1.420
1.454
1.358
1.326
1.303
1.321
1.326
1.339
1.357
1.406
11+
Table G.4. Stratified mean number, weight (kg), length (cm), and individual weight (kg) per tow of witch flounder in NEFSC offshore spring and autumn bottom trawl surveys in Gulf of Maine-Georges Bank region (strata 22-30,36-40), 1963-2005.
Year 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Number per tow 4.83 3.74 6.39 2.70 5.35 8.20 6.23 3.72 5.50 4.20 3.87 2.91 8.46 8.14 3.64 6.41 3.00 5.18 2.07 1.01 1.43 1.95 0.63 1.68 1.26 1.47 3.13 1.88 1.36 2.22 4.27 3.15 3.45 4.41 8.10 5.20 3.80 3.36
SPRING Weight per tow 3.35 2.53 4.49 2.04 4.01 6.21 3.62 2.75 3.70 1.96 2.56 1.71 3.89 4.05 1.87 2.74 1.66 2.75 1.35 0.65 0.85 0.74 0.24 0.57 0.48 0.36 0.53 0.47 0.28 0.43 0.77 0.48 0.52 0.75 1.62 1.30 1.08 0.89
Length per tow 42.3 45.3 44.7 46.5 45.8 44.8 39.3 43.9 42.3 37.2 41.7 38.2 36.0 38.0 37.2 36.3 39.9 40.3 44.1 43.4 42.3 35.8 35.2 31.5 34.8 30.3 27.4 30.6 30.5 31.0 29.0 28.1 27.3 29.5 31.4 34.2 35.5 34.6
Ave. wt. per tow 0.695 0.676 0.702 0.756 0.749 0.758 0.581 0.739 0.673 0.467 0.662 0.587 0.460 0.497 0.513 0.427 0.554 0.531 0.650 0.646 0.590 0.382 0.378 0.341 0.383 0.245 0.170 0.248 0.204 0.195 0.179 0.153 0.151 0.171 0.199 0.250 0.285 0.264
Number per tow 5.52 2.89 3.94 7.80 3.01 4.82 5.81 4.89 4.32 3.24 3.18 2.38 1.66 1.34 5.06 4.04 1.94 2.62 3.66 0.99 4.72 4.37 2.76 1.59 0.48 1.38 0.89 2.00 2.08 0.94 5.15 2.21 4.74 5.38 5.11 3.70 5.92 6.63 7.94 4.31 2.66 3.82
AUTUMN Weight per tow 3.46 2.00 2.27 4.56 2.02 3.49 4.40 3.71 2.95 2.42 2.05 1.58 1.03 0.94 3.38 2.94 1.62 2.04 2.19 0.83 2.12 2.34 1.59 1.09 0.37 0.57 0.38 0.40 0.54 0.24 0.54 0.42 0.62 1.02 0.77 0.47 0.88 1.11 1.71 1.06 0.79 1.03
Length per tow 39.7 44.2 40.6 41.2 43.7 44.8 43.5 45.0 42.1 43.9 43.6 41.0 39.8 41.9 42.0 42.8 45.2 43.7 40.4 44.7 36.7 39.7 41.9 43.3 43.9 35.2 31.4 24.7 29.2 29.5 17.0 24.9 25.7 29.7 24.9 24.2 26.3 27.1 32.3 33.2 35.4 33.3
Ave. wt. per tow 0.627 0.691 0.577 0.584 0.673 0.724 0.757 0.760 0.683 0.747 0.646 0.666 0.621 0.699 0.669 0.727 0.838 0.777 0.600 0.842 0.448 0.534 0.577 0.683 0.774 0.414 0.423 0.200 0.258 0.254 0.105 0.191 0.132 0.189 0.150 0.127 0.148 0.167 0.216 0.247 0.298 0.271
Note: No significant differences in catchability were found for witch flounder between BMV and polyvalent doors, no significant differences were found between research vessels, therefore no adjustment have been made (Byrne and Forrester, MS 1991). Spring surveys during 1973-1981 were accomplished with a 41 Yankee trawl; in all other years, a 36 Yankee trawl was used. No adjustments have been made.
2-198
SPRING 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
1 0.060 0.000 0.044 0.000 0.000 0.000 0.000 0.000 0.023 0.023 0.008 0.042 0.054 0.149 0.107 0.041 0.017 0.072 0.112 0.106 0.007 0.105 0.023 0.000 0.009 0.011
2 0.230 0.050 0.042 0.071 0.103 0.000 0.000 0.000 0.023 0.013 0.000 0.000 0.009 0.112 0.698 0.120 0.036 0.066 1.079 0.376 0.250 0.099 0.060 0.000 0.060 0.160
3 0.950 0.820 0.610 0.531 0.012 0.017 0.000 0.000 0.062 0.036 0.038 0.781 0.187 0.137 0.541 0.581 0.244 0.152 0.712 0.974 1.194 0.713 0.897 0.150 0.074 0.146
4 1.520 0.930 0.484 1.262 0.307 0.459 0.044 0.059 0.000 1.004 0.091 0.108 0.373 0.472 0.644 0.316 0.394 0.693 0.388 0.797 0.692 1.476 2.627 0.808 0.428 0.220
5 0.720 2.000 0.377 1.293 0.778 1.057 0.240 0.114 0.072 0.105 0.319 0.087 0.085 0.320 0.810 0.179 0.346 0.617 0.798 0.482 0.660 1.020 2.263 1.646 0.648 0.737
2-199
AGE 6 1.200 1.020 0.237 0.541 0.401 1.199 0.529 0.133 0.300 0.073 0.000 0.209 0.111 0.058 0.164 0.312 0.218 0.437 0.713 0.164 0.239 0.401 0.822 1.017 0.809 0.760 7 1.020 0.760 0.609 0.716 0.310 0.908 0.412 0.259 0.379 0.081 0.042 0.033 0.152 0.085 0.027 0.116 0.073 0.084 0.214 0.182 0.253 0.293 0.683 0.869 0.883 0.574
8 0.380 0.670 0.362 0.632 0.202 0.412 0.172 0.185 0.239 0.327 0.009 0.101 0.045 0.000 0.028 0.110 0.000 0.083 0.154 0.031 0.116 0.163 0.351 0.387 0.368 0.383
9 0.400 0.420 0.093 0.475 0.196 0.148 0.194 0.009 0.137 0.081 0.050 0.083 0.149 0.015 0.070 0.042 0.000 0.014 0.076 0.014 0.000 0.113 0.192 0.197 0.158 0.245
10 0.310 0.130 0.259 0.214 0.115 0.149 0.079 0.061 0.086 0.015 0.018 0.138 0.015 0.015 0.008 0.000 0.000 0.000 0.000 0.023 0.035 0.028 0.103 0.046 0.161 0.086
11 0.300 0.200 0.175 0.166 0.173 0.044 0.038 0.023 0.084 0.056 0.009 0.018 0.016 0.000 0.000 0.038 0.032 0.000 0.000 0.000 0.000 0.000 0.014 0.060 0.135 0.018
12 0.120 0.240 0.026 0.075 0.117 0.072 0.063 0.000 0.029 0.056 0.011 0.022 0.046 0.068 0.000 0.028 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
13 0.160 0.220 0.033 0.054 0.023 0.027 0.055 0.000 0.000 0.019 0.000 0.000 0.000 0.000 0.016 0.000 0.000 0.000 0.028 0.000 0.000 0.000 0.029 0.016 0.000 0.021
14+ 1.100 0.900 0.292 0.376 0.266 0.691 0.248 0.163 0.000 0.056 0.030 0.064 0.019 0.037 0.016 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.037 0.009 0.067 0.000
Table G.5. Stratified mean number per tow at age of witch flounder in NEFSC bottom trawl spring and autumn surveys (Strata 22-30, 36-40), 1980 - 2005.
Total 8.460 8.400 3.642 6.407 3.001 5.182 2.073 1.007 1.434 1.945 0.626 1.684 1.260 1.469 3.129 1.883 1.359 2.219 4.274 3.149 3.446 4.409 8.101 5.204 3.799 3.362
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
AUTUMN
0.040 0.030 0.020 0.000 0.000 0.000 0.009 0.000 0.000 0.174 0.481 0.224 0.097 2.541 0.432 0.512 0.232 0.892 0.639 0.323 0.943 0.000 0.000 0.018 0.276
0
0.000 0.070 0.000 0.008 0.000 0.000 0.000 0.000 0.007 0.018 0.088 0.021 0.029 0.672 0.156 0.203 0.092 0.339 0.082 0.521 0.096 0.039 0.000 0.000 0.072
1 0.020 0.030 0.000 0.011 0.000 0.009 0.000 0.023 0.000 0.018 0.137 0.177 0.109 0.154 0.287 0.764 0.261 0.979 0.520 1.178 0.719 0.210 0.275 0.038 0.014
2 0.000 0.240 0.058 0.507 0.093 0.059 0.000 0.000 0.725 0.082 0.380 0.661 0.259 0.544 0.532 1.624 0.785 0.522 1.363 1.514 1.408 0.952 0.431 0.075 0.086
3 0.200 0.440 0.013 1.596 0.943 0.076 0.051 0.011 0.055 0.301 0.507 0.329 0.224 0.777 0.165 0.858 1.988 0.871 0.465 1.044 1.746 3.156 1.475 0.307 0.453
4 0.260 0.610 0.027 0.758 0.991 0.610 0.266 0.023 0.012 0.009 0.219 0.290 0.054 0.219 0.395 0.472 1.386 0.770 0.303 0.600 0.674 1.886 0.997 0.580 0.987
5
7 0.360 0.270 0.241 0.444 0.535 0.482 0.309 0.192 0.215 0.017 0.023 0.067 0.000 0.022 0.106 0.000 0.066 0.329 0.110 0.275 0.229 0.612 0.331 0.315 0.498
2-200
0.280 0.460 0.076 0.548 0.605 0.684 0.353 0.046 0.036 0.021 0.024 0.145 0.061 0.058 0.037 0.229 0.441 0.383 0.165 0.364 0.589 0.813 0.532 0.770 0.826
AGE 6 0.170 0.260 0.132 0.084 0.310 0.270 0.160 0.071 0.048 0.084 0.023 0.059 0.000 0.081 0.000 0.000 0.065 0.000 0.043 0.050 0.152 0.159 0.148 0.129 0.355
8 0.150 0.180 0.015 0.137 0.149 0.103 0.112 0.000 0.046 0.078 0.025 0.030 0.019 0.000 0.043 0.011 0.037 0.000 0.012 0.037 0.049 0.058 0.071 0.222 0.054
9 0.270 0.210 0.027 0.073 0.126 0.122 0.009 0.009 0.045 0.024 0.000 0.052 0.009 0.019 0.009 0.054 0.000 0.000 0.000 0.009 0.000 0.056 0.000 0.083 0.105
10 0.040 0.170 0.032 0.114 0.073 0.029 0.010 0.000 0.079 0.000 0.000 0.028 0.019 0.042 0.000 0.000 0.033 0.000 0.000 0.000 0.000 0.000 0.046 0.021 0.072
11 0.160 0.040 0.009 0.025 0.041 0.015 0.021 0.000 0.011 0.026 0.009 0.000 0.000 0.000 0.005 0.000 0.000 0.020 0.000 0.000 0.026 0.000 0.005 0.046 0.000
12 0.120 0.130 0.039 0.000 0.132 0.089 0.052 0.023 0.043 0.000 0.055 0.000 0.019 0.011 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.019 0.000
13 0.570 0.480 0.301 0.415 0.375 0.217 0.237 0.085 0.055 0.037 0.034 0.000 0.042 0.014 0.042 0.009 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.038 0.019
14+ 2.620 3.660 0.991 4.718 4.373 2.763 1.590 0.482 1.376 0.888 2.005 2.083 0.940 5.154 2.209 4.736 5.384 5.105 3.701 5.915 6.630 7.940 4.311 2.660 3.816
Total
Table G.5. continued. Stratified mean number per tow at age of witch flounder in NEFSC bottom trawl spring and autumn surveys (Strata 22-30, 36-40), 1980-2004.
Table G.6. Parameter estimates (with associated statistics) and estimates of terminal F from ADAPT VPA formulations for witch flounder; stock sizes in >000s. Notes:
SARC 37
Re-Run of SARC 37
Revised CAA (age and length)
GARM 2005 BASE RUN
Software
NFTv2011
NFTv222
NFTv222/231
NFT 231
CAA Est.Ages
1982-2002 3-11+ 3-10
1982-2002 3-11+ 3-10
1982-2002 3-11+ 3-10
1982-2004 3-11+ 3-10
NMFS-s
3-11+
3-11+
3-11+
3-11+
NMFS-a
3-11+
3-11+
3-11+
3-11+
.791
.791
.793
.811
M.S.R. N3 (cv)
19,759 (.64)
19,759 (.64)
19,752 (.64)
3,902 (.65)
N4 (cv)
25,441 (.45)
25,441 (.45)
25,432 (.45)
4,053 (.46)
N5 (cv)
42,739 (.37)
42,739 (.37)
42,727 (.37)
9,206 (.39)
N6 (cv)
41,657 (.33)
41,657 (.33)
41,640 (.33)
14,614 (.35)
N7 (cv)
21,203 (.31)
21,203 (.31)
21,204 (.31)
19,943 (.32)
N8 (cv)
10,370 (.32)
10,370 (.32)
10,362 (.32)
17,315 (.30)
N9 (cv)
3,903 (.33)
3,903 (.33)
3,931 (.33)
8,815 (.27)
791 (.45)
791 (.45)
792 (.45)
2,245 (.37)
N10 (cv) Age 3 in T+1 (>000s)
19,760
19,760
19,752
3,902
F1
-
-
-
-
F2
-
-
-
-
F3
0.0015
0.0015
0.0015
0.0058
F4
0.0161
0.0161
0.0160
0.0323
F5
0.0268
0.0268
0.0269
0.0661
F6
0.0595
0.0595
0.0591
0.0690
F7
0.1741
0.1741
0.1748
0.0772
F8
0.2648
0.2648
0.2622
0.1136
F9
0.5526
0.5526
0.5570
0.2838
F10
0.4087
0.4087
0.4096
0.1987
F11+
0.4087
0.4087
0.4096
0.1987
Ave F 7-9
-
-
-
-
Ave F 8-9
0.4087
0.4087
0.4096
0.1987
SSB (>000 mt)
18,296
18,369
18,370
21,175
2-201
Total
Age
Total
Age
3 4 5 6 7 8 9 10 11+
3 4 5 6 7 8 9 10 11+
Table G.7.
14268 7999 8658 3022 1651 454 1322 274 783 38431
1994
15405 12175 9563 7830 4289 2752 2102 1101 7260 62477
1982
12680 12242 5958 4908 1416 662 210 642 373 39091
1995
17701 13082 9493 7114 5375 3077 1763 1440 4728 63773
1983
18854 10332 10193 4166 2644 440 323 91 181 47224
1996
16343 14923 10014 6765 4668 3160 1746 839 3844 62302
1984
19931 16114 8407 7656 2329 964 137 81 114 55733
1997
7652 13931 11487 6769 4217 2647 1344 862 2926 51835
1985
19769 17029 12890 6296 5394 1067 286 41 185 62957
1998
5417 6471 10901 7929 4039 2224 1132 599 2040 40752
1986
2-202
32280 16708 14141 10109 4111 3156 576 116 200 81397
1999
3002 4641 5221 7980 4267 2034 1146 594 1151 30036
1987
44865 27634 13893 11157 7349 2431 2010 264 665 110268
2000
9745 2563 3827 4061 5685 2222 950 544 1218 30815
1988
41852 38520 23519 11540 8521 4765 1164 1215 880 131976
2001
6215 7831 2077 3049 2887 3616 854 448 1263 28240
1989
25021 35957 32836 19374 8925 5749 2759 422 895 131938
2002
6673 4935 6336 1727 2333 1784 2298 413 900 27399
1990
12889 21498 30258 27126 15384 5704 3769 1781 1427 119836
2003
8835 5425 3661 4434 1250 1755 1100 1669 1372 29501
1991
Estimates of beginning year stock size (thousands of fish), instantaneous fishing mortality and spawning stock biomass (mt) for witch flounder estimated from virtual population analysis, 1982-2004.
4737 11047 18141 24831 21733 11474 3465 2551 1738 99717
2004
14374 7195 4294 2354 3284 858 1284 677 2128 36448
1992
3902 4054 9207 14615 19948 17316 8815 2245 3027 83129
2005
9743 12002 5032 2902 1164 2164 552 941 1319 35819
1993
Age
Age
3 4 5 6 7 8 9 10 11+
3 4 5 6 7 8 9 10 11+
Fishing Mortality
1994 0.003 0.145 0.418 0.608 0.764 0.622 0.573 0.585 0.585
1982 0.013 0.099 0.146 0.226 0.182 0.295 0.228 0.266 0.266
Table G.7. continued.
1995 0.055 0.033 0.208 0.468 1.020 0.569 0.686 0.596 0.596
1983 0.021 0.117 0.189 0.271 0.381 0.416 0.593 0.477 0.477
1996 0.007 0.056 0.136 0.431 0.859 1.013 1.234 1.100 1.100
1984 0.010 0.112 0.242 0.323 0.417 0.705 0.556 0.650 0.650
1997 0.007 0.073 0.139 0.200 0.630 1.064 1.063 1.064 1.064
1985 0.018 0.095 0.221 0.366 0.490 0.700 0.657 0.685 0.685
1998 0.018 0.036 0.093 0.276 0.386 0.466 0.754 0.520 0.520
1986 0.005 0.065 0.162 0.470 0.536 0.514 0.495 0.507 0.507
2-203
1999 0.005 0.034 0.087 0.169 0.376 0.301 0.631 0.346 0.346
1987 0.008 0.043 0.101 0.189 0.502 0.612 0.595 0.606 0.606
2000 0.002 0.011 0.036 0.120 0.283 0.587 0.353 0.474 0.474
1988 0.069 0.061 0.077 0.191 0.302 0.807 0.601 0.741 0.741
2001 0.002 0.010 0.044 0.107 0.244 0.396 0.865 0.473 0.473
1989 0.081 0.062 0.034 0.117 0.331 0.303 0.576 0.350 0.350
2002 0.002 0.023 0.041 0.081 0.298 0.272 0.288 0.277 0.277
1990 0.057 0.149 0.207 0.173 0.135 0.333 0.170 0.238 0.238
2003 0.004 0.020 0.048 0.072 0.143 0.349 0.240 0.304 0.304
1991 0.055 0.084 0.292 0.150 0.226 0.162 0.335 0.225 0.225
2004 0.006 0.032 0.066 0.069 0.077 0.114 0.284 0.199 0.199
1992 0.030 0.208 0.242 0.554 0.267 0.291 0.161 0.211 0.211
1993 0.047 0.177 0.360 0.414 0.792 0.343 0.551 0.382 0.382
1982 20 107 376 1115 1543 1634 1632 949 9521 16898
1994 26 156 637 630 585 231 864 217 876
4222
Age 3 4 5 6 7 8 9 10 11+ Total
Age 3 4 5 6 7 8 9 10 11+
Total
3946
1995 11 162 606 1205 543 353 145 510 410
1983 21 132 458 1241 1883 1544 1172 1207 5781 13439
Spawning Stock Biomass (mt)
Table G.7 continued.
3899
1996 12 113 896 1153 1053 226 197 70 181
1984 39 185 580 1243 1715 1559 1088 628 4505 11542
4209
1997 9 115 599 1845 906 464 88 62 120
1985 8 127 684 1584 1720 1388 878 666 3374 10428
2-204
5489
1998 31 247 1069 1305 1921 502 180 34 200
1986 6 91 1020 1916 1636 1218 780 487 2414 9569
6995
1999 62 300 1096 2072 1407 1499 303 95 160
1987 18 216 881 2472 1794 1072 757 479 1323 9012
8903
2000 106 464 1081 2059 2359 1048 1082 156 549
1988 69 191 746 1298 2495 1148 628 422 1392 8389
11132
2001 161 646 1782 2047 2605 1977 559 689 666
1989 71 238 360 965 1303 2010 559 367 1578 7451
14177
2002 135 681 2252 3376 2708 2468 1489 283 783
1990 18 156 587 454 999 1003 1641 358 1227 6444
18349
2003 29 412 2230 4526 4771 2358 1914 1039 1070
1991 19 104 336 887 496 1004 754 1411 1830 6842
21175
2004 21 205 1204 4003 6278 4811 1734 1490 1429
1992 62 145 464 582 1370 500 917 548 2491 7079
1993 36 230 437 695 424 1211 393 789 1612 5827
Year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Median
1645 6759 3340.087
Catch (mt) 4954 6159 6759 6192 4636 3494 3320 2199 1645 1870 2395 2973 3073 2386 2338 2065 2124 2327 2550 3241 3467 3506 3149
3901 21175 9365.6957
SSB (mt) 16897 13439 11542 10429 9568 9012 8389 7451 6443 6841 7079 5827 4222 3945 3901 4208 5489 6994 8904 11132 14175 18349 21175
2-205
0.199 1.123 0.516
Ave F 8-9 0.262 0.505 0.631 0.679 0.504 0.603 0.704 0.440 0.251 0.249 0.226 0.447 0.597 0.627 1.123 1.063 0.610 0.466 0.470 0.631 0.280 0.294 0.199
14.268
3.002 44.865 15.506 12.266
Recruits Age 3 15.405 17.701 16.343 7.652 5.417 3.002 9.745 6.215 6.673 8.835 14.374 9.743 14.268 12.680 18.854 19.931 19.769 32.280 44.865 41.852 25.021 12.889 4.737 3.902 Year Class 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Summary of witch flounder catch (mt), spawning stock biomass (mt), fully recruited fishing mortality, recruitment (age 3, thousands of fish) and the year class.
min max mean Geomean
Table G.8.
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
Year
Figure G.1. Historical 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 northern shrimp and large-mesh otter trawl fisheries.
2-206
TOTAL CATCH ('000 of fish) AT AGE 2500 2000
2000
1982
1500
1500 1000
1000
500
500
0 2000
0
1983
1500
1500 1000
1000
500
500
0 2000
1500
Numbers of fish ('000)
1000
1000
500
500
0
1500
500
500 0
0
1986
2500 2000 1500 1000
1500 1000 500
0
1987
1500
1500 1000
1000
500
500
0
1995
0
1988
1500
1500 1000
1000
500
500
0 2000
1994
500
0
2000
1993
1000
1000
2000
1992
0
1985
1500
2500 2000
1991
0
1984
1500
2000
1990
1996
0
1989
1500
1997
1500 1000
1000
500
500 0 0
1
2
3
4
5
6
7
8
9
10 11+
Age
0 0
1
2
3
4
5
6
7
8
9
10 11+
Age DISCARDS IN SHRIMP FISHERY DISCARDS IN L-M OTTER TRAWL LANDINGS
Figure G.2. Number of witch flounder (‘000 of fish) at age in the total catch, by fishery, 1982-2004. Open bar represents discards in the shrimp fishery, diagonal bar represents discards in large-mesh fishery and hatched bar represents landings.
2-207
TOTAL CATCH ('000 of fish) AT AGE 2000 1500
1998
1000 500 0 1500
1999
1000 500 0 1500
2000
Numbers of fish ('000)
1000 500 0 2000
2001
1500 1000 500 0 2000
2002
1500 1000 500 0 1500
2003
1000 500 0 1500
2004
1000 500 0
0
1
2
3
4
5
6
7
8
9 10 11+
Age
DISCARDS IN SHRIMP FISHERY DISCARDS IN L-M OTTER TRAWL FISHERY LANDINGS
Figure G.2 continued.
2-208
0.8
Mean weight (kg) at age
0.7
0.6
Age 8 0.5
Age 7 0.4
Age 6 0.3
Age 5 Age 4
0.2
0.1 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008
Year Figure G.3. Witch flounder mean weights at age in the catch, 1982 – 2004.
2-209
7
Mean weight (kg) per tow
6
A Spring
5
4
3
2
1
Autumn 0 1963
1967
1971
1975
1979
1983
1987
1991
1995
1999
2003
1991
1995
1999
2003
Year 10
B Spring
Mean number per tow
8
6
4
2
Autumn 0 1963
1967
1971
1975
1979
1983
1987
Year Figure G.4. Stratified mean weight (kg) per tow (A) and mean number per tow (B) of witch flounder in the NEFSC spring and autumn bottom trawl surveys, 1963-2005.
2-210
1.2
Catch
F
1.0
Catch (000's mt)
5 0.8 4 0.6 3 0.4
2
0.2
1 0
0.0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004
Year Figure G.5. Trends in total catch and fishing mortality for witch flounder, 1982-2004.
2-211
Average F (ages 8-9,u)
6
30
Recruits SSB
25 20
40 15 10
20
5 0
0 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005
Recruitment Year class, SSB Year Figure G.6. Trends in spawning stock biomass and recruitment (age 3) for witch flounder; 1982 – 2004.
2-212
Biomass (000's mt)
Recruits (Age 3, millions)
60
Average F (ages 8-9)
3.0
A
2.5 2.0 1.5 1.0 0.5 0.0
SSB (000's mt)
1982
24 22 20 18 16 14 12 10 8 6 4 2
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
B
1982
1984
Age 3 Recruitment (000's)
140 120
C
100 80 60 40 20 0 1982
1984
Figure G.7. Retrospective analysis results of fishing mortality(A), spawning stock biomass (B), and age 3 recruitment (C) for witch flounder.
2-213
50
Spawning Stock Biomass ('000 mt)
A 45
40 A13 projected
35
30
25
20
15 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year 0.45
B 0.40
Fishing Mortality
A13 projected 0.35
0.30
0.25
0.20
0.15 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year Figure G.8 . Comparisons of Amendment 13 projected and 2004 assessment estimates of witch flounder spawning stock biomass (A) and fishing mortality (B), 2003 - 2014. Solid lines represent the median values and dash lines represent the 25 and 75 percentiles.
2-214
