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Deep water Redfish - Rockall Bank and Reykjanes Ridge, 2006
Marine Resource  Fact Sheet
ICES Advice 2007
Deep water Redfish - Rockall Bank and Reykjanes Ridge, 2006
Fact Sheet Citation  
Deep-sea Sebastes mentella on the continental shelf in Sub-areas V, VI and XIV
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Beaked redfish, fr - Sébaste du Nord, es - Gallineta nórdica, ru - Клювач
Geographic extent of Deep water Redfish - Rockall Bank and Reykjanes Ridge
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


Changes in fishing technology and fishing patterns


In Division Va, demersal S. mentella are takenmainly by Icelandic trawlers at depths greater than 500 m. In Division Vb, the fishery is carried out mainly by Faroese trawlers, though some bycatch is taken by other countries fishing demersal species. In Subarea XIV, the catch is mainly taken as bycatch by German freezer trawlers targeting Greenland halibut. The total annual catches almost doubled in the early 1990s, but have since then decreased to the level of the 1980s. The increase was mainly caused by an increased catch in Division Va, both in the demersal and in a temporarily developed pelagic fishery, and by an increase in Subarea XIV in 1993–1994. The increased catch of S. marinus in Va in 2002 and decreased catch of S. mentella in 2001 and 2002 is due to a joint quota for S. marinus and S. mentella on the shelf, and the fishing fleet has increased the proportion taken from S. marinus in most recent years.
Assessment
 
Assessment Model
Assessment Model Entry
Data

Scientific basis


Survey data are available from the German groundfish survey in Subarea XIV (1985–2006), and from the Icelandic groundfish survey in Va (2000–2006). Cpue data are available from Icelandic trawlers in Division Va (1986–2006) and from the Faroese fishery in Division Vb (1991–2006). Faroese bottom trawl surveys are designed for other species and are therefore not considered as reliable indicators for S. mentella.

Technological advances in fishing gear have not been accounted for when using cpue as an abundance indicator, and these advances are thought to be significant.The nature of the fishery is similar to pelagic fisheries, targeting schools of fish using advancing technology. The effect of technological advances is to increase cpue. Therefore, the general decrease in cpue from the late 1980s to the early 1990s suggests a decreasing stock, but recent increase in cpue is not considered to reflect biomass increases. Prior to 2004, advice was based solely on cpue indices from the fishery. This is likely to be the cause of the discrepancy between the survey and the cpue trend.

Uncertainties in assessment and forecast


The available data did not allow for an analytical assessment.
Overall Assessment Results

Comparison with previous assessment and advice


The assessment and advice are the same as last year.
Reference Point
 

No precautionary reference points are established.
Scientific Advice

Single-stock exploitation boundaries


Exploitation boundaries in relation to precautionary considerations


ICES reiterates the previous advice that catches should not exceed 22 000 t, which corresponds to the lowest observed catch since 1980, taken in 2001. This catch level coincides with a time when survey abundance estimates derived from the major fishing grounds did not decrease.

There should be no directed fishery for demersal S. mentella in Subarea XIV until there are clear signs of improvement in the adult stock size of S. mentella in that area.

Management considerations


Sebastes mentella is a deep-sea species with late maturation and slow growth and is hence considered to be vulnerable to overexploitation. It can therefore only sustain low exploitation and management should be based on that consideration.

The advice for 2007 catch was 22 000 t, which corresponded to the lowest observed catch in Subarea V since 1980, taken in 2001 and 2004. The advised catch in 2007 and 2008 coincides with the only substantial increase in biomass indicated by the Icelandic groundfish survey (in 2001).

As this stock is at a low level, the fishable biomass of S. mentella in Subarea XIV is low, and the area is considered to be a nursery ground, ICES advises that there should be no direct fishery for S. mentella in Subarea XIV.

The present management scheme in Division Va sets a joint TAC for S. marinus and S. mentella on the shelf. This impedes direct management of each stock, and ICES repeats its advice that the two species should be managed separately.

From the German survey on the Greenland shelf there are indications of increase in biomass from 2003 and onwards. These fish will reach fishable size in the coming years. However, it is not clear whether these fish will recruit to the pelagic stock or to the demersal stock.

The stock structure of redfish S. mentella in Subareas V, VI, XII, and XIV, and in the NAFO Convention Area has been evaluated by ICES (2005). The outcome is not conclusive and supports different hypotheses (from a one-stock to a different multi-stock hypothesis). Consequently, and solely for practical reasons, the perception of the stock structure is unchanged in this report compared to the 2003 report. Additional information on stock structure has become available recently and ICES will evaluate this information in 2008.

Analysis of logbook information from 1991–2006 shows that the pelagic fishery east of the “redfish line” occurs in the same area as the bottom trawl fisheries, the two fisheries often coinciding seasonally and occurring within the same depth range. Analysis based on the same source indicates that annual catch with pelagic gear east of the “redfish line” has been decreasing over the period. The average annual pelagic catch was around 13 thousand tonnes in the period 1991–1998 (range: 4–25 thousand tonnes), but in more recent years the average annual catch has been less than 3 thousand tonnes (range: 0–8 thousand tonnes).
Management
Management unit: Yes

Management Objectives

There are no explicit management objectives for this stock.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Undefined

In the absence of reference points the state of the stock cannot be fully evaluated. Commercial cpue indicates a general decrease in stock biomass from the late 1980s to the early 1990s; after this it has been relatively stable. All available survey biomass indices have been stable in the last 5 years.
Source of information
 

ICES. 2005. ICES Advice 2005.
ICES. 2007. Report of the North-Western Working Group, 24 April–3 May 2007. ICES CM 2007/ACFM:17.
Catch and TACsSourceWeights in '000 t.
1 Deep-sea S. mentella and S. marinus combined.
2Deep-sea S. mentella only.
3In Va only.
4 For entire Subarea V.

Graphs
Source


Figure 2.4.8.1 Landings of demersal S. mentella on the continental shelf from ICES Divisions Va, Vb, VI, and XIV.
Source


Figure 2.4.8.2 Demersal S. mentella on the continental shelf. Total biomass index derived from the Icelandic autumn survey conducted in Division Va.
Source

Figure 2.4.8.3 Demersal S. mentella (>=17 cm) on the continental shelf. Survey biomass indices for East and West Greenland, derived from the German groundfish surveys.
Source 


Figure 2.4.8.4 Demersal S. mentella on the continental shelf. Geographical location of the catch in Icelandic waters as reported in logbooks from the Icelandic bottom trawl fleet.
Source


Source

Figure 2.4.8.5 Demersal S. mentella on the continental shelf. Cpue, relative to 1986, from the Icelandic bottom trawl fishery in Division Va. Cpue based on a GLM model, based on data from logbooks and where at least 50% of the total catch in each tow was demersal S. mentella. Also shown is fishing effort (hours fished in thousands).

Source

Figure 2.4.8.6 Demersal S. mentella on the continental shelf. Cpue (kg/hour) and fishing effort (in thousands) from the Faroese OB fleet and where 70% of the total catch was deep-sea S. mentella.Landing table

Table 2.4.8.1 Nominal landings (tonnes) of demersal S. mentella on the continental shelf and slopes by ICES Division.
Source
- ICES Division -
Year Va Vb VI XII XIV Total
1978 3 902 7 767 18 0 5 403 17 090
1979 7 694 7 869 819 0 5 131 21 513
1980 10 197 5 119 1 109 0 10 406 26 831
1981 19 689 4 607 1 008 0 19 391 44 695
1982 18 492 7 631 626 0 12 140 38 889
1983 37 115 5 990 396 0 15 207 58 708
1984 24 493 7 704 609 0 9 126 41 932
1985 24 768 10 560 247 0 9 376 44 951
1986 18 898 15 176 242 0 12 138 46 454
1987 19 293 11 395 478 0 6 407 37 573
1988 14 290 10 488 590 0 6 065 31 433
1989 40 269 10 928 424 0 2 284 53 905
1990 28 429 9 330 348 0 6 097 44 204
1991 47 651 12 897 273 0 7 057 67 879
1992 43 414 12 533 134 0 7 022 63 103
1993 51 221 7 801 346 0 14 828 74 196
1994 56 720 6 899 642 0 19 305 83 566
1995 48 708 5 670 536 0 819 55 733
1996 34 741 5 337 1 048 0 730 41 856
1997 37 876 4 558 419 0 199 43 051
1998 33 125 4 089 298 3 1 376 38 890
1999 28 590 5 294 243 0 865 34 992
2000 31 393 4 841 885 0 986 38 105
2001 17 230 4 696 36 0 927 23 889
2002 19 045 2 552 20 0 1 903 23 520
2003 28 478 2 114 197 0 376 31 164
2004 17 564 3 931 6 0 389 21 890
2005 20 563 1 593 111 0 120 22 387
20061) 17 412 3 421 179 0 12 21 023

1) Provisional.
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