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Blue Ling - Faroes Grounds, Rockall and Celtic shelf
Marine Resource  Fact Sheet
ICES Advice 2009
Blue Ling - Faroes Grounds, Rockall and Celtic shelf
Fact Sheet Citation  
Blue ling in Subdivisions Vb, VI and VII (Faroes Rockall and Celtic shelf)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Blue ling, fr - Lingue bleue, es - Maruca azul, ru - Мольва голубая (=биркеланга)
Geographic extent of Blue Ling - Faroes Grounds, Rockall and Celtic shelf
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Reference year: 2008
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateUndefinedUncertain/Not assessed
Abundance levelUndefinedUncertain/Not assessed

Cpue information suggests that the abundance of blue ling remains at a low level (Figure 9.4.11.2.2).
Habitat and Biology
Depth zone: Slope (200 m - 1000 m).   Vertical distribution: Demersal/Benthic.  

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Assessment
 
Assessment Model
Methodology

Scientific basis

Survey data were available, but only for a short period.

Cpue based on data from spawning aggregations is not a reliable indicator of exploitable biomass. However, French cpue calculated for a range of reference areas showed consistent trends. There has been a strong decline in the mean length in French landings for blue ling in this management unit between 1985 and 1996. The mean length has remained low after 1996 (Figure 9.4.11.2.3).

The abundance index from the commercial fishery is derived from directed lpues of a French reference fleet in a reference area from trips where blue ling is more than 10% of the total landings. The reference consists of large high-sea trawlers (>45 m overall length) that were already fishing in the early 1990s. The number of vessels in the reference fleet have declined over the years and the mean age of the vessels has increased. Several factors (month, depth, rectangle, vessel, skipper) are shown to have explanatory power on cpue, but they are not included in the calculation of the cpue.

Landings by ICES Subareas and Division by country are given in Table 9.4.11.2.1 and Figure 9.4.11.2.1. Landings dataseries have been extended back in time to include data not previously presented.

Previous assessments carried out in 2004 (using stock reduction) and 2006 (using Catch Survey Analysis (CSA)) indicated that current exploitable biomass was at a very low level. The information presented this year indicates that there is no reason to change this interpretation.

Information from the fishing industry

In collaboration with the French industry, IFREMER has carried out investigations to refine cpue series for French trawlers. A new time-series based on haul-by-haul data was initiated by the French industry. This series only goes back to 2000.

It shows that 65% of the hauls dedicated to deep-sea fish catch blue ling, at depths between 500 and 1400 m. The ‘deep-sea’ hauls (35%) where no blue ling is reported are at slightly deeper depths (700–1400 m).

Information collected under the French deep-water sampling programme indicates that there are no discards of this species in the French trawl fishery. There is no information available on discards in other fleets.

Comparison with previous assessment and advice

The perception and basis for advice on blue ling in Vb, VI, and VII has not changed.
Overall Assessment Results


Table 9.4.11.2.1. Blue ling (Molva dypterygia). Working Group estimates of landings (tonnes). Landings of Blue ling in Subdivision Vb1
Year Faroes France(2) Germany(2) Norway(3) E & W(2) Scotland (1) Ireland Russia (2) Total
1966   839   430         1269
1967     1006 238         1244
1968     1838 823         2661
1969     303 798         1101
1970     348 2718         3066
1971     1367 557         1924
1972     2730 1203         3933
1973 51 80 3009 4003 4       7147
1974 43 390 1808 1554 3       3798
1975 17 2147 1528 2492 1       6185
1976 42 10475 896 1482         12895
1977 23 6977 870 858 4       8732
1978 423 3369 744 237 35       4808
1979 1072 2683 691 331         4777
1980 1187 2427 5905 304   1     9824
1981 1481 371 2867 167         4886
1982 2761 843 2538 121         6263
1983 3933 668 222 256         5079
1984 6453 515 214 105         7287
1985 4038 1193 217 140         5588
1986 4830 2578 197 94         7699
1987 3361 3246 152 81         6840
1988 3487 3036 49 94         6666
1989 2468 1802 51 228         4549
1990 946 3073 71 450         4540
1991 1573 1013 36 196 1       2819
1992 1918 407 21 390 4       2740
1993 2088 192 24 218 19       2541
1994 1065 147 3 173         1388
1995 1606 588 2 38 4       2238
1996 1100 301 3 82         1486
1997 778 1656   65 11       2510
1998 1026 1411 0 24 1       2462
1999 1730 1068 4 38 4       2844
2000 1677 575 1 163 33     1 2450
2001 1407 433 4 130 11   2   1987
2002 1003 574   274 8       1859
2003 2465 1133   12 1       3611
2004 751 1131   20       13 1915
2005 1028 781   15 1       1825
2006 1230 839   21 1     16 2107
2007* 1276 796   116 8     36 2232
*Preliminary. (1) Included in Vb2. (2) Includes Vb2 (3) includes Vb2 up to 1974


Table 9.4.11.2.1. Cont’d. Landings of Blue ling in Subdivision Vb2.
Year Faroes Norway Scotland (1) E & W Total
1966         0
1967         0
1968         0
1969         0
1970         0
1971         0
1972         0
1973         0
1974         0
1975 1       1
1976 6 37     43
1977   86     86
1978 7 83     90
1979 14 87     101
1980 36 159     195
1981 48 93     141
1982 128 66     194
1983 463 182     645
1984 757 50     807
1985 396 70     466
1986 81 41     122
1987 209 90     299
1988 2788 72     2860
1989 622 95     717
1990 68 191     259
1991 71 51 21   143
1992 1705 256 1   1962
1993 182 22 91   295
1994 239 16 1   256
1995 162 36 4   202
1996 42 62 12   116
1997 229 48 11   288
1998 64 29 29   122
1999 15 49 24   88
2000 0 37 37   74
2001 0 69 63   132
2002   21 140   161
2003   84 120   204
2004 710 6 68   784
2005 609 14 68   691
2006 632 34 16   682
2007* 647 6 102   755


Table 9.4.11.2.1. Cont’d. Landings of Blue ling in Division Via.
Year Faroes France Germany Ireland Norway Spain (2) E & W Scotland Lithuania(1) Total
1966         20         20
1967     37   35         72
1968         126         126
1969     6   112         118
1970         176         176
1971         15         15
1972   696     14         710
1973   18000     25         18025
1974 33 15000 1218   371   164     16786
1975   5000 2941   20   8     7969
1976   5462 818   10   1     6291
1977   7940 470   16   556     8982
1978   5495 2498   19   21     8033
1979   3064 993   2   279     4338
1980   2124 773   10         2907
1981   3338 335   11     1   3685
1982   3430 79   16   99     3624
1983   5233 11   118   13     5375
1984   3653 183   45   5     3886
1985 56 5670 5   75   2     5808
1986   8254 7   47   2 1   8311
1987   9389 45   51   1     9486
1988 14 6614 2   29   2 1   6662
1989 6 7382 2   143       7533
1990   4882 44   54     1   4981
1991 8 4261 18   63   1 35   4386
1992 4 5483 4   129     24   5644
1993   4311 48 3 27   13 42   4444
1994   2999 24 73 90 433 1 91   3711
1995 0 2835   11 96 392 34 738   4106
1996 0 4115 4   50 681 9 1407   6266
1997 0 3845   1 29 190 789 1021   5875
1998 0 4644 3 1 21 142 11 1416   6238
1999 0 3730   10 55 119 5 1105   5024
2000   4443 94 9 102 108 24 1300   6080
2001   2693 6 52 117 797 116 2136   5917
2002   2005   62 61 285 16 2027   4456
2003 7 2000   2 106 195 3 428   2741
2004 10 2259   1 24 24 1 482   2801
2005 17 2031   2 33 210   390 29 2712
2006 13 1804   1 49 27 3 433   2330
2007* 13 1784     31 49   130 1 2008
*Preliminary. (1) Includes VIb for all countries up to (and including) 1974, (2) Includes VIb


Table 9.4.11.2.1. Cont’d. Landings of Blue ling in Division VIb.
Year Poland Russia Faroes France Germany Norway E & W Scotland Iceland Ireland Estonia Total
1975     1     37           38
1976     13     6           19
1977     6 36   7           49
1978     3 58   8           69
1979     4 652 187 28           871
1980       3827 5526 8           9361
1981       534 3944 5           4483
1982       263 554 13   1       831
1983       243 38 50   2       333
1984     133 3281   43           3457
1985     11 7263 31 38           7343
1986     1845 2928 39 66 7 1       4886
1987     350 10 356 76 3 10       805
1988     2000 499 37 42 9 14       2601
1989     1292 61 22 217   16       1608
1990     360 703   127   2       1192
1991     111 2482 6 102 5 15       2721
1992     231 348 2 50 2 14       647
1993     51 373 109 50 66 57       706
1994     5 89 104 33 3 25       259
1995     1 305 189 12 11 38       556
1996     0 87 92 7 37 74       297
1997     138 331   6 65 562 1     1103
1998     76 469   13 190 287 122 11   1168
1999     204 690   9 168 2411 610 4 4096
2000       508   184 500 966 7   2165
2001     238 202 1 256 337 1803 4 85 2926
2002   3 79 319   273 141 497   1   1313
2003 4 2   510   102 14 113     5 750
2004 1 5 4 486   2 10 96     3 607
2005   15 1 234   1 9 80       340
2006     15 313   2 4 29       363
2007*   1 3 109   4 5 35       157
*Preliminary.


Table 9.4.11.2.1. Cont’d. Blue ling landings in Division Vb and Subareas VI and VII.
Blue ling Vb VI VII Total
1966 1269 20 22 1311
1967 1244 72 293 1609
1968 2661 126 223 3010
1969 1101 118 212 1431
1970 3066 176 406 3648
1971 1924 15 321 2260
1972 3933 710 339 4982
1973 7147 18025 230 25402
1974 3798 16786 365 20949
1975 6186 8007 383 14576
1976 12938 6310 598 19846
1977 8818 9031 352 18201
1978 4898 8102 280 13280
1979 4878 5209 691 10778
1980 10019 12268 483 22770
1981 5027 8168 114 13309
1982 6457 4455 58 10970
1983 5724 5708 59 11491
1984 8094 7343 67 15504
1985 6054 13151 51 19256
1986 7821 13197 0 21018
1987 7139 10291 0 17430
1988 9526 9263 22 18811
1989 5266 9141 293 14700
1990 4799 6173 223 11195
1991 2962 7107 212 10281
1992 4702 6291 406 11399
1993 2836 5150 321 8307
1994 1644 3970 339 5953
1995 2440 4662 230 7332
1996 1602 6563 365 8530
1997 2798 6978 383 10159
1998 2584 7406 598 10588
1999 2932 9120 352 12404
2000 2524 8245 280 11049
2001 2119 8843 691 11653
2002 2020 5769 483 8272
2003 3815 3491 114 7420
2004 2699 3408 58 6165
2005 2516 3052 59 5627
2006 2789 2693 67 5549
2007* 2987 2165 51 5203
*Provisional


Figure 9.4.11.2.1. Blue ling in Subdivisions Vb, VI, and VII. Total international landings (tonnes).


Figure 9.4.11.2.2. Blue ling. Directed lpues for French reference fleet (landings for fishing trip where blue ling >10% of total landings) in Vb and VI.


Figure 9.4.11.2.3. Blue ling. Mean length in French trawl landings in Subdivisions Vb, VI, and VII.

Reference Point
 

In common with other deep-water stocks, Ulim has previously been proposed at 0.2* virgin biomass and Upa at 0.5* virgin biomass (ICES, 1998). In the absence of abundance indices that correspond to the start of the fishery, the reference points cannot be calculated.
Scientific Advice

Single-stock exploitation boundaries

There should be no directed fisheries for blue ling in Subdivisions Vb, VI, and VII and measures should be implemented to minimize bycatches in mixed fisheries. Blue ling is susceptible to sequential depletion of spawning aggregations and closed areas to protect spawning aggregations should therefore be maintained and expanded where appropriate.
Management
 
Management Advice

Management considerations

Blue ling is now mostly taken in deep-water fisheries in Subdivisions Vb ,VI, and XIIb. Landings from Subdivision VII are small. Landings during 2005–2007 have been around 5500 t per year which is about 60% of the landings during 1995–2004.

Historically, a major part of this fishery has been on spawning aggregations. Experience in Divisions Va and Vb indicates that once blue ling is fished down in an area it does not recover even when fishing pressure has been low.

The introduction of closed areas to protect spawning aggregations should be accelerated. ICES has issued an answer to a request by NEAFC on spawning areas for blue ling in Section 9.3.2.7.

It is suggested that the blue ling management unit should be expanded to include the western part of Hatton Bank (new ICES Division XIIb).
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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