Advice June 2012

9.4.11.2 Advice June 2012 ECOREGION STOCK Widely distributed and migratory stocks Blue ling (Molva dypterygia) in Division Vb and Subareas VI and VII Advice for 2013 and 2014 Based on the ICES approach for data-limited stocks, ICES advises that catches should be no higher than 3900 t in 2013. Existing management measures should be continued. Spatial management to prevent targeted fishing on spawning aggregations should be expanded to cover spawning areas in Division VIb. This is the first year ICES is providing quantitative advice for data-limited stocks (see Quality considerations). Stock status MSY (F MSY ) Precautionary approach (F pa,f lim ) MSY (B trigger ) Precautionary approach (B pa,b lim ) Qualitative evaluation F (Fishing Mortality) 2009 2011 Below target Undefined SSB (Spawning-Stock Biomass) 2009 2011 Unknown, B trigger undefined Undefined Increasing International landings (tonnes) 40000 30000 20000 10000 0 1966 1971 1976 1981 1986 1991 1996 2001 2006 2011* VII VI Vb Harvest rate 0.0 0.1 0.2 0.3 0.4 200,000 150,000 100,000 50,000 1970 1980 1990 2000 2010 Total Biomass (tonn Fishing mortality 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 1990 1995 2000 2005 2010 Total abundance (millions 0 10 20 30 40 1990 1995 2000 2005 2010 Figure 9.4.11.2.1 Blue ling in Division Vb and Subareas VI and VII. Top left: Landings (thousand tonnes). Top right: Harvest rate and total biomass (solid line) from stock reduction analysis (SRA, FL aspm ). Bottom left: Fishing mortality from the MYCC model. The blue shaded area depicts F MSY proxies from F = 0.12 to 0.18. Bottom right: Total abundance (ages 9+) from MYCC. The stock reduction analysis (SRA) shows a large decrease in biomass between 1970 and 1990. The SRA (based on abundance indices and landings) and the multi-year catch curve (MYCC; based on age composition and landings) models both indicate decreasing fishing mortality since 2003 2004, below possible F MSY proxies and increasing biomass. This is consistent with the observed increase of the mean size in landings. ICES Advice 2012, Book 9 1

Management plans No specific management objectives are known to ICES. Biology Blue ling is a gadoid species that grows much faster than most deep-water species. It is vulnerable to exploitation because fisheries can target the spawning aggregations. The fisheries The main fisheries are those by Faroese trawlers in Division Vb and French trawlers in Subarea VI and, to a lesser extent, Division Vb. Total international landings from Subarea VII are very small, as are bycatches in other fisheries. Landings by Faroese trawlers are mostly taken in the spawning season. Historically, this was also the case for French trawlers fishing in Division Vb and Subarea VI. However, in recent years blue ling has been taken mainly as a bycatch in French trawl fisheries for roundnose grenadier and black scabbardfish. Catch distribution Total catches (2011) were 3 kt, where 99% were landings, <1% discards, 0% industrial bycatch, and 0% unaccounted removals. Effects of the fisheries on the ecosystem Deep-water bottom trawls impact the ocean floor, causing potential damage to deep-water coral communities. This is mitigated by closed areas to protect vulnerable marine ecosystems (VMEs). As this fishery is part of a mixed fisheries, any effort on blue ling also impacts other commercial and non-commercial deep-water species. Quality considerations All available information suggests that discarding in French fisheries is not significant (discards <1%). Other fisheries may be constrained by quotas that lead to some discarding, and the extent of discarding is unknown for some fleets. Age estimation was resumed in France through the EU Data Collection Framework (DCF), after a disruption from 1994. Age estimation requires accurate laboratory equipment and optics to read the thin growth increments from thin otolith slices. Age estimates are still not validated, and an age-reading workshop would be useful. The numbers of blue ling captured in the Scottish and Irish survey are small and the depth of peak abundance is not sampled. The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or the stock overfished. Scientific basis Assessment type Input data Discards and bycatch Indicators Other information Working group report Stock Reduction Analysis (SRA), a model fitted to catches and abundance indices; Multi- Catch Curves (MYCC), a model fitted to age composition and total catch in order to estimate annual total mortality (Z). International landings 1966 2011; landings per unit effort (lpue) from logbooks and French tallybooks; Faroese, Scottish, and Irish surveys; age composition of French landings (1988 1994 and 2009 2011). Not significant. Biomass indices from commercial lpues, mean length in French and Faroese landings, survey indices. None. WGDEEP 2 ICES Advice 2012, Book 9

9.4.11.2 Supporting information June 2012 ECOREGION STOCK Widely distributed and migratory stocks Blue ling (Molva dypterygia) in Division Vb and Subareas VI and VII Reference points Preliminary investigations undertaken by ICES in 2012 indicate that for an assumed natural mortality of 0.18, an appropriate proxy for F MSY lies within the range of 0.12 0.18. Outlook for 2013 and 2014 No analytical assessment is available for this stock. Therefore, detailed management options cannot be presented. ICES approach to data-limited stocks Two independent stock assessment models return similar views that the stock was overexploited, with fishing mortality showing a peak in 2000 and then decreasing. These models indicate that stock abundance has been increasing since 2003 or 2004. The history of the exploitation is longer than most time-series of data, only landings time-series could be reconstructed back to 1966, i.e. early times of the fishery. The time-series of length distribution starts from the late 1980s and landings per unit of effort (lpue) from tallybook records in 2000. However, the SRA model provides an estimate of the biomass in the late 1960s when exploitation was very low. This estimate can be regarded as a virgin biomass estimate, a reference situation not usually available for demersal fish stocks. The stock abundance has increased by a factor of 1.7 since 2002 according to SRA, and 2.8 since 2004 according to MYCC. However, the absolute level is estimated at about 25% of the unexploited level according to SRA. Fishing mortality in the period 2008 to 2011 was well below all suggested F MSY proxy values. However, current biomass in relation to B trigger is unknown and there is a possibility that the stock is below this point. It would therefore not be appropriate to allow F to increase to F MSY until the biomass relative to B trigger can be assessed. Maintaining recent catches (average of landings 2008 to 2011) would be expected to result in increasing SSB. This would imply a catch of 3.9 kt in 2013. Blue ling is susceptible to sequential depletion of spawning aggregations. High landings were caught at spawning time until the 2000s. Current spatial measures to protect spawning aggregations should therefore be maintained, and new spatial measures should be identified and implemented where appropriate, in particular in international waters in Divisions Vb and VIb. Additional considerations The EU management unit for this stock was expanded in 2011 to include EU and international waters of Division Vb. As a consequence the assessment and management areas are now consistent. The EU further introduced a in Subarea XII, so that all areas where blue ling occur are now covered by s. The western part of Hatton Bank (ICES Division XIIb) is contiguous with the eastern part of Hatton Bank (ICES Division VIb). Catches in ICES Division XIIb are likely to come from the same stock as catches in Division Vb and Subareas VI and VII. However, catch data from Division XIIb are not considered reliable and would probably add noise to the assessment. In 2009, EU protection areas were introduced for spawning aggregations of blue ling on the edge of the Scottish continental shelf and at the edge of Rosemary Bank (both in Division VIa). Entry/exit regulations apply and vessels may not retain more than 6 t of blue ling from these areas per trip. When retaining 6 t vessels must exit the area and are not allowed to re-enter such areas before landing. These vessels may not discard any quantity of blue ling. Consequently, there remains some directed fishing for blue ling. The effectiveness of these protection areas in reducing catches from directed fisheries should be examined. Some spawning grounds on the eastern and northeastern parts of Hatton Bank currently remain open to fishing. Some areas are closed to bottom fishing gears on Rockall and Hatton Bank to protect cold-water corals. It should be investigated whether the extent of protection afforded to spawning aggregations of blue ling is adequate, or whether it needs to be extended further. ICES Advice 2012, Book 9 3

1.4 Mean length in French landings Biomass index 1.2 1.0 0.8 0.6 0.4 0.2 1985 1990 1995 2000 2005 2010 mean length (cm) 75 80 85 90 95 100 105 Q1 Q2 Q3 Q4 1985 1990 1995 2000 2005 2010 Figure 9.4.11.2.2 Blue ling in Division Vb and Subareas VI and VII. Left: Annual mean standardized lpue of blue ling from French logbook data, relative index. Middle: Annual mean standardized lpue of blue ling from French tallybook data, relative index. Right: Standardized time-series of lpue from logbook data. Because of restricted opportunities for fishing in 2011, the value of the catches in 2011 may be depressed. Sources ICES. 2008. Report of the ICES Advisory Committee, 2008. ICES Advice, 2008. Book 9. 345 pp. ICES. 2012. Report of the Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP), 29 March 05 April 2012, ICES Headquarters, Copenhagen. ICES CM 2012/ACOM:17. 4 ICES Advice 2012, Book 9

Table 9.4.11.2.1 Blue ling in Division Vb and Subareas VI and VII. ICES advice, management, and landings. ICES Advice Predicted catch corresp. to advice EU Division Vb (Faroese waters) 1 EU Subareas VI and VII Faroese Subareas VI and VII Norway Divisions IIa and Vb, and Subareas IV, VI, and VII ICES landings Division Vb and Subareas VI and VII 2003 No direct fisheries 2 3.24 3.678 0.94 7.4 2004 Biennial 3.24 3.678 0.9-6.2 2005 No direct fisheries 2-3.24 3.137 0.9 0.2 5.6 2006 Biennial - 3.065 3.137 0.4 0.2 5.6 2007 No direct fisheries - 3.065 2.510 0.2 0.16 5.6 2008 Biennial - 3.065 2.009 0.2 0.15 3.9 2009 No direct fisheries - 3.065 2.009 0.15 0.15 4.1 2010 Biennial - 2.700 1.732 0.150 0.150 4.7 2011 No direct fishery and effort to limit bycatch. A reduction in catches should be considered - 0 1.717 0 0.150 2.9 2012 No new advice, same as 2011 0 1.882 0 0.150 2013 Average catch 2008 3.9 to 2011 2014 No new advice, same as 2013 3.9 Weights in thousand tonnes. 1 for ling and blue ling. Including a bycatch of roundnose grenadier and black scabbardfish. 2 Advice for blue ling in the Northeast Atlantic (not split by different assessment units). ICES Advice 2012, Book 9 5

Table 9.4.11.2.2a Blue ling in Division Vb and Subareas VI and VII. ICES estimates of landings, used for assessment (tonnes). Faroes France Germany Norway E & W Scotland Ireland Russia Lithuania Poland Iceland Estonia Spain Total 1966 839 450 1289 1967 1043 273 1316 1968 1838 949 2787 1969 309 910 1219 1970 348 2894 3242 1971 1367 652 2019 1972 696 2730 1607 5033 1973 51 18080 3009 6175 4 27319 1974 76 15390 3026 12391 167 31050 1975 19 7147 4469 9526 9 21170 1976 61 15937 1714 4867 1 22580 1977 29 14953 1340 3564 560 12500 32946 1978 433 8922 3242 2691 56 15344 1979 1090 6399 1871 732 279 10371 1980 1223 8378 12204 1165 1 22971 1981 1529 4243 7146 851 1 13770 1982 2889 4536 3171 665 99 1 11361 1983 4396 6144 271 1617 13 2 12443 1984 7343 7449 397 2771 5 17965 1985 4501 14126 253 3499 2 22381 1986 6756 13760 243 3243 9 2 24013 1987 3920 12645 553 2010 4 10 19142 1988 8289 10222 90 3238 11 15 21865 1989 4388 10242 75 1605 0 16 0 0 0 0 0 0 0 16326 1990 1374 10336 115 1038 0 3 0 0 0 0 0 0 0 12866 1991 1763 10072 60 553 7 72 0 0 0 0 0 0 0 12527 1992 3858 9277 27 722 6 45 13935 1993 2321 7901 181 887 119 222 3 11634 1994 1309 4187 131 599 16 147 75 8 6472 1995 1769 4272 191 1802 132 801 17 26 9010 1996 1142 4878 99 1552 145 1630 42 9488 1997 1145 6397 16 1171 1169 1621 19 1 11539 1998 1166 7116 9 635 708 1786 21 122 44 11607 1999 1949 5682 8 534 489 3569 64 610 118 13023 2000 1677 5815 99 1037 610 2335 155 1 130 11859 2001 1645 3685 15 1646 506 4033 1449 16 85 128 13208 2002 1082 3185 8 1740 276 2773 1031 3 28 84 10210 2003 2472 3707 2 1001 32 693 58 2 29 4 5 84 8089 2004 1475 3956 2 885 19 647 39 18 38 1 3 30 7113 2005 1655 3109 1215 12 538 24 15 1 50 6619 2006 1939 3006 937 11 478 9 16 2 62 6460 2007 1880 3334 572 19 161 4 37 1 76 6084 2008 975 2529 574 2 212 122 2 12 4428 2009 978 2557 350 346 1 2 4234 2010 1539 2466 150 360 48 4563 2011* 1125 1645 104 74 2948 *Preliminary. 6 ICES Advice 2012, Book 9

Table 9.4.11.2.2b Blue ling in Division Vb and Subareas VI and VII. Official STATLANT landings from ICES database (tonnes). Estonia Faeroe Islands France Germany Iceland Ireland Lithuania Norway Poland Russian Federation Spain UK Total 1966 0 0 0 839 0 0 0 450 0 0 0 0 1289 1967 0 0 0 1043 0 0 0 273 0 0 0 0 1316 1968 0 0 0 1838 0 0 0 949 0 0 0 0 2787 1969 0 0 0 309 0 0 0 910 0 0 0 0 1219 1970 0 0 0 348 0 0 0 2894 0 0 0 0 3242 1971 0 0 0 1367 0 0 0 572 0 0 0 0 1939 1972 0 0 0 2730 0 0 0 1217 0 0 0 0 3947 1973 0 51 0 3009 0 0 0 4028 0 0 0 4 7092 1974 0 76 0 3026 0 0 0 1925 0 0 0 167 5194 1975 0 19 0 4469 0 0 0 2549 0 0 0 9 7046 1976 0 61 15944 1714 0 0 0 1535 0 0 0 2 19256 1977 0 29 14964 1340 0 0 0 967 0 0 0 568 17868 1978 0 433 8943 3334 0 0 0 347 0 0 0 56 13113 1979 0 1090 6404 1871 0 0 0 448 0 0 0 279 10092 1980 0 1223 8380 12204 0 0 0 481 0 0 2 2 22292 1981 0 1529 4260 7146 0 0 0 277 0 0 0 1 13213 1982 0 2889 4540 3171 0 0 0 216 0 0 0 100 10916 1983 0 4396 6166 272 0 0 0 608 0 0 0 15 11457 1984 0 7343 7461 397 0 0 0 243 0 0 0 5 15449 1985 0 4501 14158 253 0 0 0 327 0 0 0 2 19241 1986 0 6725 12384 243 0 0 0 242 0 0 0 24 19618 1987 0 3071 12672 529 0 0 0 298 0 0 0 85 16655 1988 0 8289 9892 89 0 0 0 237 0 0 0 26 18533 1989 0 4388 9137 75 0 0 0 685 0 0 0 16 14301 1990 0 1374 6194 115 0 0 0 822 0 0 0 4 8509 1991 0 1763 5914 60 0 0 0 412 0 0 0 60 8209 1992 0 3858 3976 27 0 0 0 828 0 0 0 53 8742 1993 0 2321 3905 181 0 3 0 302 0 0 0 252 6964 1994 0 1309 2854 131 0 74 0 313 0 0 0 156 4837 1995 0 1769 3441 192 0 14 0 182 0 0 0 888 6486 1996 0 1142 4013 99 0 0 0 202 0 0 0 1693 7149 1997 0 1145 4690 8 1 1 0 150 0 0 0 2633 8628 1998 0 1166 5881 6 122 22 0 88 0 0 111 2247 9643 1999 0 1949 0 6 610 41 0 152 0 0 143 3903 6804 2000 0 0 5503 97 0 89 0 491 0 0 298 2908 9386 2001 85 1643 3536 13 0 818 16 578 1 0 140 4512 11342 2002 22 1082 3328 6 2 578 28 629 8 3 1023 2795 9504 2003 5 2472 3763 1 0 30 29 304 4 2 288 577 7475 2004 3 1475 3922 1 0 20 38 52 1 18 0 662 6192 2005 5 1655 3103 1 0 13 1 63 0 15 182 3745 8783 2006 1 1940 3046 0 0 5 2 106 0 16 93 487 5696 2007 0 1880 3123 0 0 2 1 253 0 37 81 285 5662 2008 0 975 3055 0 0 0 2 110 0 122 0 217 4481 2009 0 979 2604 0 0 0 0 96 0 16 188 346 4229 2010 0 1539 2475 0 0 0 0 159 0 0 1 361 4535 ICES Advice 2012, Book 9 7