Fisheries and Resources Monitoring System

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Norway lobster - Irish Sea
Marine Resource  Fact Sheet
ICES Advice 2012
Norway lobster - Irish Sea
Fact Sheet Citation  
Nephrops in Division VII
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Norway lobster, fr - Langoustine, es - Cigala
Geographic extent of Norway lobster - Irish Sea
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2012
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateUndefinedUncertain/Not assessed
Abundance levelUndefinedUncertain/Not assessed
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Demersal/Benthic.  


Nephrops is limited to muddy habitat, and requires sediment with a silt and clay content of between 10–100% to excavate its burrows. This means that the distribution of suitable sediment defines the species distribution. Adult Nephrops only undertake very small scale movements (a few 100 m) but larval transfer may occur between separate mud patches in some areas. This makes some stocks, particularly those with lower average density, vulnerable to localized depletion. Catch rates and composition vary daily and seasonally between different areas and sexes due to different emergence patterns and underlying population densities. After the onset of maturity male Nephrops grow faster and attain a large size than female. Density limits growth and grounds with high Nephrops density (>0.7/m2) have smaller average size that those with low density.

Environmental influence on the stock

Temperature and hydrographic factors, particularly during the larval phase are critical to recruitment success in Nephrops. Some stocks in Division VII such as FU15 have well known and understood larval retention mechanisms (i.e. Western Irish Sea Gyre). Other stocks such as the Porcupine Bank have less well understood larval retention mechanisms. This results in very different population structure, productivity and vulnerability to fishing. Increasing water temperature leading to shorter larval development times is thought to improve recruitment in areas such as the Irish Sea. Increased storminess related to the NAO has also been linked to reduced recruitment and low catch rates several years later on the Porcupine Bank.

Effects of the fisheries on the ecosystem

Trawling for Nephrops results in bycatch and discards of other commercial species, including cod, haddock, whiting, hake, monkfish, and megrim. Given that 80 mm is the predominant mesh size used in Nephrops fisheries the resulting discard rates of small Nephrops and fish can be high.

The high mud content and soft nature of Nephrops grounds means that trawling readily marks the seabed, trawl marks remaining visible for some time. Despite the high intensity of fishing (some areas are impacted >7 times/year) burrowing fauna can be seen re-emerging from freshly trawled grounds, implying that there is some resilience to trawling.
Geographical Distribution
Jurisdictional distribution: Shared between nations

Water Area Overview
Spatial Scale: Sub-Regional


Ecoregion: Celtic Sea.
Geo References
Resource Structure
Considered a single stock: Yes
Assessment
 
Scientific Advice

A summary of the advice for all areas can be found in Table 5.4.34.1.

There is no information available on the trends in the stock or exploitation status for FU18 and the rectangles outside the FUs (‘other rectangles’) for which ICES provides advice. ICES advises that the catches in the FU18 and other rectangles should not increase.
Overall Assessment Results
Figure 5.4.34.1 Nephrops Functional Units in Subarea VII (around Ireland). The TAC for Subarea VII applies to the area bounded by the red line. The FUs within the TAC area are shaded.
Table 5.4.34.2 Nephrops in Subarea VII. ICES estimates of landings (tonnes) from all individual Functional Units within TAC Subarea VII.
Table 5.4.34.2 Nephrops in Subarea VII. ICES estimates of landings (tonnes) from all individual Functional Units within TAC Subarea VII.
Year FU 14 - Irish Sea East FU 15 - Irish Sea West FU 16 - Porcupine Bank FU 17 - Aran Grounds FU 18 - Ireland North West Coast FU 19 - Ireland South West and South East coast FUs 20-21+22 - Labadie & Smalls* FUs 20–21 - Labadie FU 22 -Smalls Other statistical rectangles Outside FUs Total Landings ICES Subarea VII TAC for VII
1978 961 7,296 1,744 481           249 10,730  
1979 900 8,948 2,269 452           237 12,807  
1980 730 4,578 2,925 442           205 8,880  
1981 829 7,249 3,381 414           382 12,255  
1982 869 9,315 4,289 210           234 14,917  
1983 763 9,448 3,426 131     3,667     174 17,609  
1984 602 7,760 3,571 324     3,653     187 16,097  
1985 498 6,901 3,919 207     3,599     194 15,317  
1986 671 9,978 2,591 147     2,638     113 16,138  
1987 449 9,753 2,499 62     3,409     107 16,279 24,700
1988 462 8,586 2,375 828     3,165     140 15,557 24,700
1989 401 8,128 2,115 344   899 4,005     134 16,026 26,000
1990 563 8,300 1,895 519   754 4,290     102 16,423 26,000
1991 747 9,554 1,640 410   1,077 3,295     169 16,892 26,000
1992 427 7,541 2,015 372   888 4,165     409 15,816 20,000
1993 515 8,102 1,857 372 10 905 4,358     455 16,573 20,000
1994 447 7,606 2,512 729 126 390 4,843     570 17,223 20,000
1995 584 7,796 2,936 866 26 695 5,198     397 18,498 23,000
1996 475 7,247 2,230 525 46 888 4,602     623 16,636 23,000
1997 566 9,971 2,409 841 15 756 3,991     340 18,889 23,000
1998 388 9,128 2,155 1,410 78 827 3,819     514 18,320 23,000
1999 624 10,786 2,289 1,140 16 579   1,710 1,152 322 18,618 23,000
2000 567 8,370 911 880 9 696   2,865 1,778 243 16,319 21,000
2001 532 7,441 1,222 913 2 815   2,903 1,833 368 16,029 18,900
2002 577 6,793 1,327 1,154 14 1,318   1,949 2,674 243 16,049 17,790
2003 376 7,065 907 933 16 1,239   2,050 2,953 186 15,726 17,790
2004 472 7,270 1,525 525 22 1,074   1,827 2,443 161 15,319 17,450
2005 570 6,554 2,312 778 15 711   2,426 2,469 180 16,015 19,544
2006 628 7,561 2,120 637 14 741   1,752 2,523 270 16,246 21,498
2007 959 8,491 2,186 913 3 957   2,886 2,419 206 19,020 25,153
2008 681 10,508 1,000 1,057 1 866   3,114 2,980 322 20,529 25153
2009 708 9,198 825 625 10 833   2,245 3,145 107 17,696 24650
2010 582 8,963 917 1,000 7 722   2,842 1,793 359 17,185 22432
2011 561 10,162 1,187 600 13 608   1,617 1,237 109 16,094 21759
Average 608 8,304 2,161 625 23 836 3,919 2,322 2,261 265 16,139  
Assessment Model

Scientific basis


The assessments and advice for Nephrops stocks in Functional Units 14 and 15 (Irish Sea), 17 (Aran), 19 (southeast and southwest coast of Ireland) and 22 (the Smalls) are primarily based on abundance estimates from underwater TV (UWTV) surveys together with fishery landings data and estimates of quantities of discards. Additional indicators of changes in stocks are derived from trends in length compositions and sex ratio in the catches, fishery lpue, and (for FU15) trawl survey catch rates. The assessments and advice for FU 16 (Porcupine Bank) and FU 20–21 (Celtic Sea) are based on a range of indicators of stock trends including fishery lpue, trawl survey catch-rates, size compositions and sex ratio and the data limited approach.
Management
Management unit: Yes

Management Advice


Table 5.4.34.1 Nephrops in Subarea VII. ICES advice, management and landings by Functional Unit plus other rectangles.
Year     Predicted landings corresponding to ICES advice

Agreed

TAC

ICES landings
 

Irish Sea East

(FU14)

Irish Sea West (FU15)

Porcupine Bank (FU16)

Aran

Grounds

(FU17)

Ireland SW and SE Coast

(FU19)

Celtic Sea- Labadie

(FU20–21)

Celtic Sea- Smalls

FU22

Other rec-tangles

1)

   
Division VIIa VIIb,c,j,k VIIg,h VIIg,f   VII VII
1992 8.9 3.8 ~3.8   20.0 15.8
1993 9.4 ~4.0 3.8   20.0 16.6
1994 9.4 ~4.0 3.8   20.0 17.2
1995 9.4 ~4.0 3.8   20.0 18.5
1996 9.4 4.0 3.8   23.0 16.6
1997 9.4 4.0 3.8   23.0 18.9
1998 9.4 4.0 3.8   23.0 18.3
1999 9.4 4.0 3.8   23.0 18.6
2000 9.4 4.0 3.8   21.0 16.3
2001 9.4 4.0 3.8   18.9 16.0
2002 9.55 4.44 3.8   17.79 16.0
2003 9.55 4.44 3.8   17.79 15.7
2004 9.55 3.3 4.6   17.45 15.3
2005 9.55 3.3 4.6   19.544 16.0
2006 9.55 3.3 4.6   21.498 16.2
2007 -2) -2) -3) -3) -3) -2)   25.153 19.0
2008 -2) -2) -3) -3) -3) < 5.3   25.153 20.5
2009 <1.0 < 8.5 < 1.0 < 0.9 < 0.8 < 5.3 < 0.2 24.650 17.7
2010 <1.0 < 5.5 0 < 0.5 < 0.8 < 5.3 < 0.2 22.432 17.2
2011 <0.68 <9.5 0 <0.9 -4) -4) < 0.2 21.759 16.1
2012 <0.96 <9.8 -5) <1.1 -6) -6) <2.3 4) 21.759  
2013 <0.88 <9.3 <1.1 <0.89 <0.82 <2.5 <2.6 4)    

Weights in ‘000 t.

1) Prior to 2009, landings corresponding to advice for other rectangles and FU 18 were included with adjacent FUs.

2) No increase in effort.

3) Constrain effort to recent levels.

4) ICES provided advice based on MSY and Precautionary Scenarios

5) No increase in catches.

6) Reduce catches.
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. Nephrops in Division VII. Report of the ICES Advisory Committee, 2012. ICES Advice, June 2012. Click to openhttp://www.ices.dk/committe/acom/comwork/report/2012/2012/Nep-VII.pdf
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