FIRMS - Marine Resource fact sheets - Blue Ling - Faroes Grounds, Rockall and Celtic shelf

Blue Ling - Faroes Grounds, Rockall and Celtic shelf

Marine Resource Fact Sheet

ICES Advice 2009

Blue Ling - Faroes Grounds, Rockall and Celtic shelf

Blue ling in Subdivisions Vb, VI and VII (Faroes Rockall and Celtic shelf)

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International Council for the Exploration of the Sea (ICES) – More

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Species:

Molva dypterygia

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

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Area Details

Main Descriptors
Considered a single stock: Yes Spatial Scale: Sub-Regional Reference year: 2008

Table of Contents

Habitat and Biology - Water Area Overview - Assessment - Management - Biological State and Trend - Source of information

Biological State and Trend

State & Trend Descriptors
	Partner	FIRMS
Exploitation rate	Undefined	Uncertain/Not assessed
Abundance level	Undefined	Uncertain/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, U_lim has previously been proposed at 0.2* virgin biomass and U_pa 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.

Fisheries and Resources Monitoring System