Fishery Resources Monitoring System

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Saithe - North Sea, Skaggerak, West of Scotland and Rockall, 2012
Marine Resource  Fact Sheet
ICES Advice 2012
Saithe - North Sea, Skaggerak, West of Scotland and Rockall, 2012
Fact Sheet Citation  
Saithe in Subarea IV (North Sea) Division IIIa (Skagerrak) and Subarea VI (West of Scotland and Rockall)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Monitoring periodPreviously monitored as: Saithe - West of Scotland and Rockall
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Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Saithe(=Pollock), fr - Lieu noir, es - Carbonero(=Colín), ar - قدّيّة سوداء, zh - 青鳕, ru - Сайда
Geographic extent of Saithe - North Sea, Skaggerak, West of Scotland and Rockall
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes
 
 
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Demersal/Benthic.  


The juveniles (ages 0–2 years) generally occur in shallow coastal areas where they are protected from large fisheries. The fish are long-lived (20+ years) and tend to form large aggregations to a higher extent than for instance cod. Saithe starts to mature at age 4 (15% mature) and at age 7 all fish can be regarded as being mature.

Environmental influence on the stock

A decrease in the mean weight-at-age has been observed since the mid-1980s, but this trend has now been reversed. Current information is insufficient to establish whether these reductions are linked to changes in the environment. There is no indication that the observed decline in weight-at-age is density dependent.
Geographical Distribution
Jurisdictional distribution: Shared between nations

Water Area Overview
Spatial Scale: Sub-Regional


Ecoregion: North Sea
Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

The fisheries


Saithe in the North Sea are mainly taken in a directed trawl fishery in deep water along the Northern Shelf edge and the Norwegian Trench. Analyses show a substantial shift in the Norwegian and German trawlers’ fishing pattern after 2008, both in time and spatial distribution. The importance of the fisheries on the spawning aggregations in the first quarter of the year has declined.
Catch distribution Catch 2011 = 97 kt, of which approximately 95% are taken by bottom trawl and 5% by other gears. Discards are low.



Effects of the fisheries on the ecosystem

Hiddink et al. (2006) estimates that in areas of bottom trawl activity in the North Sea, benthic biomass and production is reduced by 56% and 21%, respectively, compared with an unfished situation. North Sea saithe fisheries are known to have less impact on the seafloor than most other bottom trawl fisheries.
Assessment
 
Scientific Advice

ICES advises on the basis of the EU–Norway management plan that landings in 2013 should be no more than 100 684 tonnes for the whole assessment area.
Overall Assessment Results
Assessment Model

Quality consideration


Age distribution of Norwegian catch data has been revised substantially for 2010, which influences the biomass estimate in the whole assessment. Conflicting signals between the scientific surveys have become more apparent. All scientific surveys on adults have shortcomings in depth range (IBTS-Q3) or coverage (NORACU). Catches from older age classes in the surveys are not representative and therefore commercial cpue indices are used for tuning. Catch sampling data from the Norwegian fishing industry should be improved.
Figure 6.4.12.2 Saithe in Subareas IV and VI, and Division IIIa. Historical assessment results (final-year recruitment estimates included). The 2010 assessment is not included since this was only a forecast based on the 2009 assessment.

Scientific basis

Assessment type Age-based assessment model (XSA).
Input data Three survey indices (NORACU, IBTS-Q3, NORASS);
  three commercial indices (FRATRB_VI, GER-OTB_IV, NORTR_VI2).
Discards and bycatch Not included in the assessment.
Indicators None.
Other information Benchmarked in January 2011 (revised in October 2011).


Management
Management unit: Yes


Management plans


The EU–Norway agreed management plan as updated in December 2008 (Annex 6.4.12) was evaluated by ICES (ICES, 2008), and considered to be consistent with the precautionary approach in the short term (< 5 years).
Biological State and Trend
Exploitation rate: Below limit
Abundance level: Above trigger
Source of information
 

The above excerpts are from the first two pages of the ICES advice, the supporting information to this advice can be read in full at the following reference:
ICES. Saithe in Subarea IV (North Sea), Division IIIa (Skagerrak), and Subarea VI (West of Scotland and Rockall). Report of the ICES Advisory Committee, 2012. ICES Advice, 2012. Click to openhttp://www.ices.dk/committe/acom/comwork/report/2012/2012/sai-3a46.pdf
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