Habitat and Biology
Depth zone: Shelf Vertical distribution: Demersal/benthic
Geographical Distribution
Jurisdictional distribution: Shared between nations
Resource Structure
Considered a single stock: Yes
Exploitation
Factors affecting the fisheries and the stockRegulations and their effectsSince 1992, directed fishery has only been allowed by small coastal vessels fishing with longlines and gillnets. Bycatches of Greenland halibut in the trawl fisheries have been limited by rules on permissible bycatch per haul and allowable bycatch limit on-board the vessel. This regulation was changed in 2004. The regulation now refers to the catch proportions on-board a vessel, not the proportions per haul. This allows the targeting of Greenland halibut, once cod fishing has ceased during a trip.
The regulations enforced in 1992 reduced the total landings of Greenland halibut by trawlers from 20 000 t to about 6000 t. Since then and until 1998 because of the change in allowable bycatch, annual trawler landings have varied between 5000 and 8000 t without any clear trend. The increase of trawler landings in 1999 and again in 2004 is likely to be a result of less restrictive bycatch regulations. Landings of Greenland halibut from the directed longline and gillnet fisheries have also increased in recent years to well above the level of 2500 t set by the Norwegian authorities. This is attributed to the increased difficulties of regulating a fishery that only lasts for a few weeks.
Assessment
Assessment Model
Assessment Model Entry
Data
Environmental conditionsGreenland halibut occur over a wide range of depths (from 20 to 2200 m) and temperatures (from –1.5°C to 10°C). Young Greenland halibut occur mostly in the northeastern Barents Sea (Svalbard and further east to Franz Josef Land) where the presence of adult Greenland halibut or other predators appears to be minimal.
Scientific basisData and methodsAn exploratory assessment was based on commercial catch-at-age data, two survey series, and one commercial cpue series.
Uncertainties in assessment and forecastThe assessment is uncertain due to age-reading problems and lack of contrast in the data. The age-reading issue is being addressed and should be resolved in future years (2009) which could only influence the management for the 2011 onwards. Corrections to the whole time-series are required. Recruitment in 2005 and 2006 is considered uncertain as there are no recruitment surveys.
Overall Assessment Results
Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential and considering ecosystem effectsThere is no estimate of high-yield reference points.
Comparison with previous assessment and adviceThe 2006 and 2007 assessments both indicate similar trends in SSB and exploitation. The advice is unchanged.
Reference Point
No precautionary reference points have been established for this stock. Due to problems in age readings, it is not possible to estimate fishing mortality reference points in absolute terms.
Scientific Advice
Single-stock exploitation boundariesExploitation boundaries in relation to precautionary considerationsThe stock has remained at a relatively low size in the last 25 years at catch levels of 15 000–25 000 t. In order to increase the SSB, catches should be kept well below that range. Catches for 2008 should be below 13 000 t as advised since 2003; this is the level below which SSB has increased in the past.
Management considerationsThe stock has been at a low level for several years and it is a long-lived species, which can only sustain low exploitation. The recent increase in stock size, based on the tentative assessment and the fishery-independent surveys appears to have stopped. This is associated with catches increasing above 13 000 t. Given the state of the stock and the lack of information, the fishery should not be above 13 000 t until there is better information and firm evidence of a larger stock size.
Russia and Norway were each allowed catches of up to 1500 t of Greenland halibut for research and surveillance purposes in 2002. This research quota has been increased in 2006 to 4500 t for each country, as compared to the advised maximum catch of 13 000 t. ICES cannot see the scientific need for research quotas of this magnitude.
Management
Considered a management unit: Yes
Management Objectives
No explicit management objectives have been established for this stock.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Undefined
In the absence of defined reference points the status of the stock cannot be fully evaluated. The tentative assessment indicates that SSB has been low since the late 1980s, but a slight increase is indicated until 2004. After 2004 the SSB has decreased again. There are indications of a decreasing trend in fishing mortality since the 1990s. Recruitment has been stable at a low level since the 1980s. Recent recruitment estimates are very uncertain.
Source of information
ICES. 2007. Report of the Arctic Fisheries Working Group, 18–27 April 2007. ICES CM 2007/ACFM:16.
Catch and TACs
SourceWeights in ‘000 t.
1Set by Norwegian authorities.
2Set by Norwegian authorities for the non-trawl fishery; allowable bycatch in the trawl fishery is additional to this.
Graphs
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| Source |
Figure 3.4.7.1 Greenland halibut in Subareas I & II. The assessment is only indicative of trends.
Landing table
 |
| Source |
 |
| Source |
 |
| Source |
Table 3.4.7.1 Greenland halibut. Nominal catch (t) by countries (Subarea I, Divisions IIa, and IIb combined) as officially reported to ICES.
Source1 Provisional figures.
2 Working Group figures.
3 USSR prior to 1991.
Table 3.4.7.2 Greenland halibut. Nominal catch (t) by countries in Subarea I as officially reported to ICES.
Source1Provisional figures.
2 Working Group figures.
3 USSR prior to 1991.
Table 3.4.7.3 Greenland halibut. Nominal catch (t) by countries in Division IIa as officially reported to ICES.
Source1Provisional figures.
2Working Group figure.
3As reported to Norwegian authorities.
4Includes Division IIb.
5 USSR prior to 1991.
Table 3.4.7.4 Greenland halibut. Nominal catch (t) by countries in Division IIb as officially reported to ICES.
Source1Provisional figures.
2Working Group figure.
3As reported to Norwegian authorities.
4 USSR prior to 1991.
Table 3.4.7.5 Greenland halibut in Subareas I & II.
Source
|
Year
|
Landings
|
|
-
|
-
|
|
|
tonnes
|
|
1964
|
40391
|
|
1965
|
34751
|
|
1966
|
26321
|
|
1967
|
24267
|
|
1968
|
26168
|
|
1969
|
43789
|
|
1970
|
89484
|
|
1971
|
79034
|
|
1972
|
43055
|
|
1973
|
29938
|
|
1974
|
37763
|
|
1975
|
38172
|
|
1976
|
36074
|
|
1977
|
28827
|
|
1978
|
24617
|
|
1979
|
17312
|
|
1980
|
13284
|
|
1981
|
15018
|
|
1982
|
16789
|
|
1983
|
22147
|
|
1984
|
21883
|
|
1985
|
19945
|
|
1986
|
22875
|
|
1987
|
19112
|
|
1988
|
19587
|
|
1989
|
20138
|
|
1990
|
23183
|
|
1991
|
33320
|
|
1992
|
8602
|
|
1993
|
11933
|
|
1994
|
9226
|
|
1995
|
11734
|
|
1996
|
14347
|
|
1997
|
9410
|
|
1998
|
11893
|
|
1999
|
19517
|
|
2000
|
14437
|
|
2001
|
16307
|
|
2002
|
13161
|
|
2003
|
13578
|
|
2004
|
18800
|
|
2005
|
18834
|
|
2006
|
17910
|
|
Average
|
25045
|
ICES 
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