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Megrim - West of Scotland and Rockall
Marine Resource  Fact Sheet
ICES Advice 2009
Megrim - West of Scotland and Rockall
Fact Sheet Citation  
Megrim in Sub-area VI (West of Scotland and Rockall)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Megrim, fr - Cardine franche, es - Gallo del Norte
Geographic extent of Megrim - West of Scotland and Rockall
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2008
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateUnknownUncertain/Not assessed
Abundance levelUnknownUncertain/Not assessed


Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long term yield

Fishing mortality in relation to

agreed target

Comment
Unknown Unknown Unknown NA  



The state of the stock is unknown. There are major uncertainties about catch and effort data for megrim, as well as limited knowledge about population dynamics.
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Demersal/Benthic.  

Geographical Distribution
Jurisdictional distribution: National

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Factors affecting the fisheries and the stock

The effects of regulations

New mesh regulations introduced in Division VIa which have increased the mesh size from 100 to 120 mm (vessels >15 m) will result in an increase in the length of first capture. This measure, coupled with further effort restrictions associated with the long-term management plan for cod (Council Regulation (EC) No 1342/2008) is likely to result in further effort displacement away from the shelf fisheries in Division VIa, with indications of effort switching to Rockall (Division VIb). However, at this stage it is not possible to quantify this until an integrated analysis of VMS and logbook data is conducted.

Changes in fishing technology and fishing patterns

Effort restrictions and changes in fishing patterns associated with the long-term management plan for cod (Council Regulation (EC) No 1342/2008) are described in more detail in section 5.4.21. Mesh size increases implemented in 2009 are expected to benefit the megrim stock in Division VIa. The expected increased effort in Division VIb may increase exploitation on the Division VIb megrim population.

No information is available on changes in the French and Spanish fleets operating in this area.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

The information basis for megrim is being developed, with improvements to both industry-related data and surveys. There is currently only four years of survey data and that is considered not long enough for an assessment of the state of the stock.

Uncertainties in assessment and forecast

The quality of the available landings data (specifically the area misreporting), discard information, lack of effort data and cpue data for the main fleet in the fishery, severely hampers the ability of ICES to carry out an assessment for this stock. For stocks like megrim and anglerfish on the Northern Shelf, there is a general need for improved spatio-temporal resolution of commercial catch and effort data through integration of VMS and logbook data.

Comparison with previous assessment and advice

In recent years there has been no analytical assessment for this stock and the management advice has been based on average landings. This year the advice is based on effort.
Overall Assessment Results

Table 5.4.28.4 Table 5.4.28.5
Reference Point
 

No precautionary reference points have been defined for this stock.
Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of exploitation boundaries in relation to precautionary considerations that the effort in fisheries that catch megrim should not be allowed to increase.


Table 5.4.28.1 Megrim (Lepidorhombus spp) in Subarea VI. Single-stock exploitation boundaries (advice), management, and landings
Year

ICES Advice / from 2004 Single-stock exploitation boundaries

Predicted catch corresp. to advice Predicted catch corresponding to single-stock boundaries

Agreed TAC1

Official Landings2

ICES Landings3

1987 Not assessed -   4.4 3.9 -
1988 Not assessed -   4.84 4.5 -
1989 Not assessed -   4.84 2.7 -
1990 Not assessed -   4.84 2.7 3.7
1991 No advice -   4.84 3.2 3.7
1992 No advice -   4.84 3.2 4.8
1993 No long-term gain in increased F -   4.84 3 4.3
1994 No long-term gain in increased F -   4.84 3 4.3
1995 No advice -   4.84 3.3 4.6
1996 No advice -   4.84 2.9 5.3
1997 No advice -   4.84 2.8 4.6
1998 Adequate catch controls -   4.84 2.7 4.2
1999 Maintain current TAC 4.84   4.84 2.5 3.8
2000 Maintain current TAC 4.84   4.84 2.4 3.6
2001 Maintain current TAC 4.84   4.36 2.4 3.3
2002 Maintain current TAC 4.36   4.36 1.6 2.3
2003 Maintain current TAC 4.36   4.36 1.7 2.3
2004 4 Reduce TAC to recent landings   3.6 3.6 1.4 1.8
2005 4 Reduce TAC to recent landings   2.3 2.88 0.9 n/a
2006 4 Reduce TAC to recent landings   2.3 2.88 0.9 1.1
2007 Reduce TAC to recent landings   2.1 2.88 1.01 1.3
             
             
             
2008 Reduce TAC to recent landings   1.4 2.59 1.38 1.6
2009 Same advice as last year   1.4 2.79    
2010 No increase in effort   -      

Weights in ‘000 t.

1 Division Vb(EC) and Subareas VI, XII, and XIV.

2 Divisions VIa and VIb.

3 Landings in Divisions VIa and VIb and unallocated landings from Subarea IV. Landings in Vb (EC), XII, and XIV are negligible.

4 Single-stock boundaries and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits.



Table 5.4.28.2 Megrim (Lepidorhombus spp) in Subarea IV. Single-stock exploitation boundaries (advice), management, and landings.
Year ICES Advice / from 2004 Single-stock exploitation boundaries5 Predicted catch corresponding to single-stock boundaries Agreed TAC2 Official Landings3 ICES Landings4
           
2004 na1 na1 1.89 1.16 0.739
2005 na1 na1 1.74 0.99 n/a
2006 na1 na1 1.74 1.39 1.18
2007 na1 na1 1.48 1.52 1.05
2008 na1 na1 1.59 1.57 1.32
2009 na1 na1 1.59    
2010 No increase in effort -      

Weights in ‘000 t.

1 Not applicable - IV not considered by ICES.

2 Divisions IV and IIIa.

3 Division IV.

4 Landings in Division IV less misreported landings into Subarea VIa.

5 Single-stock boundaries and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits.



Table 5.4.28.3 Megrim (Lepidorhombus spp) in Subareas IV and VI. Single-stock exploitation boundaries (advice), management, and landings
Year ICES Advice / from 2004 Single-stock exploitation boundaries4 Predicted catch corresponding to single-stock boundaries Agreed TAC2 Official Landings3 ICES Landings
           
2004 na1 na1 5.49 2.56 2.59
2005 na1 na1 4.62 1.89 n/a
2006 na1 na1 4.62 2.29 2.40
2007 na1 na1 4.36 2.53 2.45
2008 na1 na1 4.18 2.95 2.96
2009 na1 na1 4.38    
2010 No increase in effort -      

Weights in ‘000 t.

1 Not applicable – combined VI and IV not considered by ICES.

2 Divisions VI, IV and IIIa.

3 Divisions IV and VI.

4 Single-stock boundaries and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits.



Management
Management unit: Yes

Management Objectives

No explicit management objectives have been set for this stock.
Management Advice

Management considerations

A recently developed fishery independent survey suggests an increasing trend in biomass in both areas VI and IV since 2005.

Since 2009, ICES also provides advice on megrim in Subarea IV (North Sea). This is because the spatial distribution of landings data and survey catches provide good evidence to suggest that megrim population is contiguous between Divisions IVa and VIa.

Recent reductions in effort in Scotland and Ireland are considered to have contributed to the decline of landings in Subarea VI. Landings in VI are well below the TAC. Uptake by France, who account for 44% of the TAC, is very low (~11%). Official landings in Subarea IV and Division IIa in recent years are close to the TAC.

Area misreporting has been prevalent as megrim catches were misreported from Subarea VI into Subarea IV, due to restrictive quotas for anglerfish (i.e. vessels targeting anglerfish misreported all landings including megrim from Subarea VI into Subarea IV). The extent of this problem is unknown and should be quantified through integrated logbook and VMS analysis.
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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