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Black Scabbardfish - Northeast Atlantic, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Black Scabbardfish - Northeast Atlantic, 2008
Fact Sheet Citation  
Black scabbardfish (Aphanopus carbo)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Black scabbardfish, fr - Sabre noir, es - Sable negro, ru - Рыба-сабля угольная
Geographic extent of Black Scabbardfish - Northeast Atlantic
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes
 
 
Habitat and Biology
Depth zone: Slope (200 m - 1000 m).   Vertical distribution: Demersal/Benthic.  

Geographical Distribution
Jurisdictional distribution: Straddling between High Seas and EEZ

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Factors affecting the fisheries and the stock

Regulations and their effects

There is a licensing scheme and effort limitation in Division Vb and a TAC management in Subareas V, VI, VII, and XII.
Assessment
 
Assessment Model
Methodology

Scientific basis

Summaries of the total landings for all areas and by Subarea are given in Table 9.4.16.1 and Figure 9.4.16.1. Landings by Subarea and by nation are given in Tables 9.4.16.2 and 9.4.16.3.

French trawl cpue and Portuguese longline cpue data series are presented in Figures 9.4.16.2 and 9.4.16.3.

The abundance index from the commercial fishery is derived from directed lpues of a French reference fleet in a reference area from trips where black scabbardfish comprises 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.

Black scabbardfish is not known to be discarded; this implies that lpues are equivalent to cpues for this species.

Information from the fishing industry

In collaboration with the French industry, IFREMER has carried out investigations to refine the cpue series for French trawlers. A new time-series based on haul-by-haul data was initiated by the French industry, but this series only goes back to 2000. It shows that 72% of the hauls dedicated to deep-sea fisheries catch black scabbardfish at depths between 700 and 1300 m. The ‘deep-sea’ hauls (28%) where no black scabbardfish are reported are at lower (500–800 m) or deeper depths (1300–1400 m).

Information collected under the French deep-water sampling programme indicates that there are no discards of this species in the French trawl fishery.

Comparison with previous assessment and advice

There is no change in the perception of black scabbardfish. Due to the persistent decline in cpue in Areas Vb, VI, VII, and XII, ICES recommends further reduction in catches compared to the previous advice.
Overall Assessment Results


Figure 9.4.16.1. Landings of black scabbardfish by management unit (in tonnes and as proportion).


Figure 9.4.16.2. Black scabbardfish lpues for French trawlers in a reference area (28 statistical rectangles to the northwest of Scotland) in Vb and VI: directed lpue of the reference fleet (landings for fishing trips where black scabbardfish comprise >10% of total landings).


Figure 9.4.16.3. Black scabbardfish relative cpue from the Portuguese longline fishery.


Table 9.4.16.1. Landings of black scabbardfish by Subarea (tonnes).
Year II IV Va Vb VI VI+VII VII VIII IX X XII XIV Total
1988 0 0 0 0 0 0   0 2602 0 0 0 2602
1989 0 3 0 170 184 0 0 0 3473 0 0 0 3830
1990 1 70 0 427 1023 0 10 0 3274 0 0 0 4805
1991 0 107 0 135 2307 0 94 1 3978 166 2 0 6790
1992 0 219 0 105 3113 0 322 9 4389 370 7 0 8534
1993 0 34 0 286 3054 8 468 11 4513 2 1168 0 9544
1994 0 45 1 160 2433 3 662 5 3429 0 833 0 7571
1995 1 8 0 424 2634 0 641 0 4272 3 309 0 8291
1996 0 7 0 186 3019 1 658 3 3686 11 235 0 7805
1997 0 2 1 68 2533 3 461 2 3553 3 209 0 6834
1998 0 11 0 180 1708 4 388 5 3147 99 471 2 6015
1999 0 7 9 154 1820 2 354 11 2741 112 120 0 5330
2000 0 5 10 311 3101 100 527 33 2371 113 887 90 7548
2001 0 11 5 870 4162 255 723 23 2744 16 1224 0 10033
2002 0 24 13 1751 4541 1093 356 33 2692 2 909 8 11422
2003 0 4 14 1634 3043 164 241 34 2630 91 173 2 8031
2004 0 5 19 868 2967 312 262 39 2463 113 248 0 7295
2005 0 2 19 553 2727 79 175 26 2746 379 250 0 6957
2006 0 13 23 784 1873   446 52 2674 65 135 0 6065
2007 0 1 1 767 1909   419 27 3453 0 0 0 6577

Table 9.4.16.2. Table 9.4.16.3.
Reference Point
 

No reference points have been defined for this species.
Scientific Advice

Single-stock exploitation boundaries

Despite the lower landings in recent years, cpue in Areas Vb, VI, VII, and XII has declined to about 20% of its initial level. ICES recommends that catches should be constrained to 2000 t (50% of the level before the expansion of the fishery, 1993–1997). The fishery should not be allowed to expand unless it can be shown that it is sustainable.

Cpue in Subareas VIII and IX does not indicate any clear trends, but no information is available before 1996. Recent levels of catches do not appear to have had a negative impact. ICES recommends that catches in these areas should be constrained to 2800 t (average 2003–2007) and to collect information that can be used to evaluate a long-term sustainable level of exploitation.

The fishery in other areas should not be allowed to expand unless it can be shown that it is sustainable.
Management
Management unit: Yes

Management Objectives

There are no management objectives for this species.
Management Advice

Management considerations

In Subareas Vb, VI, VII, and XII, black scabbardfish is mainly taken in mixed trawl fisheries along with roundnose grenadier and sharks, although some trawl fisheries can target specific species within the mixed fishery. Due to the mixed nature of the trawl fisheries any measure taken to manage this species in these areas should take into account the advice given for other species taken in the same mixed fishery.

The relative abundance index for this stock has declined to about 20% of its initial level. As the start of the cpue series may not correspond to the start of the fishery, the true decline is likely to be greater than this. In general, biomass associated with MSY is about 40% of the unexploited biomass. The average catch during the time period of the decline in cpue must have generated a fishing mortality greater than Fmsy. Therefore, catches should be reduced by more than 50% to reduce F to Fmsy.

The period before the expansion of the fishery is taken as the years 1993–1997 (average landings 4091 t).

In the waters off mainland Portugal black scabbardfish is taken in a targeted artisanal longline fishery.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Undefined

The stock structure is uncertain. This section deals with a species distributed over a wide area which may be composed of several populations. Three management units are considered:

  • Northern (Subareas Vb, VI, VII, and XIIb);
  • Southern (Subareas VIII and IX);
  • Other areas (Subareas I, II, IIIa, IV, X, Va, and XIV).


The status of the species is unknown. In the northern area, indicators show a decline in abundance since 1990 (Figure 9.4.16.2). In the southern area indicators have been relatively stable during the past decade (Figure 9.4.16.3). In the other areas only very small catches have been taken.

Due to its low productivity, black scabbardfish can only sustain low rates of exploitation.
Source of information
 
ICES. 2009. Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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