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Norway lobster - West European Basin (Porcupine Bank, Aran Grounds, Ireland NW coast, Ireland SW and SE coast)
Marine Resource  Fact Sheet
ICES Advice 2009
Norway lobster - West European Basin (Porcupine Bank, Aran Grounds, Ireland NW coast, Ireland SW and SE coast)
Fact Sheet Citation  
Nephrops in Divisions VIIb,c,j,k (Management Area L)
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 - West European Basin (Porcupine Bank, Aran Grounds, Ireland NW coast, Ireland SW and SE coast)
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 rateUndefinedUncertain/Not assessed
Abundance levelUndefinedUncertain/Not assessed

The state of the stock is uncertain. Effort, landings and size distribution indicate that exploitation rate has been high in the last 5 years. Fishery independent survey information indicates that recruitment has been very weak since 2004 and the stock has declined to a low level.

Landings per unit of effort (lpue) show a generally declining trend in most fleets over the time-series available. Mean size indicators in all commercial fleets and a survey indicate a large increase in mean size for both sexes in the past five years. There has been a large change in sex ratio in the survey catches and fishery landings with females Nephrops accounting for a larger proportion Landings have declined by 57% between 2007 and 2008.
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

Changes in fishing technology and fishing patterns

The Nephrops fishery on the Porcupine Bank is both seasonal and opportunistic with increased targeting during periods of high Nephrops emergence and good weather. Effort in the Irish and French fleets increased rapidly between 2003 and 2007 when increasingly Nephrops directed fisheries developed. In 2008, effort declined substantially. Although Spanish effort has not increased there has been a large increase in lpue, indicating increased targeting of Nephrops. The increase in Irish effort is mainly due to increasing enforcement of anglerfish quotas and larger vessels switching to Nephrops fisheries.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

The assessment is based on evidence from several indicators. The available data includes commercial landings compositions for males and females for the main fleets, catch rates and length distributions from the Spanish Porcupine Bank survey (2001–2008) and lpue and effort data for the main fleets.

Uncertainties in assessment and forecast

Large differences are seen in the length compositions from different countries, which could indicate different selection patterns or different high grading practices between fleets. Nevertheless all data shows a similar trend to larger size in recent years. Combined landed length distributions are used to calculate the exploitation and recruitment proxies. Several uncertainties are associated with this approach, particularly as no length frequency data for Irish landings in 2006 and 2007 and no discard data are available for any fleets.

The size distribution and catch rates in fishery-independent survey confirm the weak recent recruitment and decline in stock abundance. There was a year effect in the gear performance during the 2008 survey but this is not expected to change the overall conclusion.

The increase in the exploitation proxy is coincident with an increase in effort and landings. There are concerns about the accuracy of the catch statistics and lpue information in some fleets. Growth rates cannot be well determined. Analytical assessments or catch forecasts are not feasible at present.

Comparison with previous assessment and advice

The assessment is based on similar indicators to last year. The 2008 data shows a continued deterioration in stock status

The advice in 2008 was to reduce catches to below 1000 t. Because of the continued decline in the stock, the advice now calls for a reduction in catches to the lowest possible level.
Overall Assessment Results


Table 5.4.34.3.2. Nephrops FU 16 (Porcupine Bank).. Landings (tonnes) by country.
Year France Rep. of
Ireland
Spain UK Total
           
1965 514       514
1966 0       0
1967 441       441
1968 441       441
1969 609       609
1970 256       256
1971 500   1444   1944
1972 0   1738   1738
1973 811   2135   2946
1974 900   1894   2794
1975 0   2150   2150
1976 6   1321   1327
1977 0   1545   1545
1978 2   1742   1744
1979 14   2255   2269
1980 21   2904   2925
1981 66   3315   3381
1982 358   3931   4289
1983 615   2811   3426
1984 1067   2504   3571
1985 1181   2738   3919
1986 1060   1462 69 2591
1987 609   1677 213 2499
1988 600   1555 220 2375
1989 324 350 1417 24 2115
1990 336 169 1349 41 1895
1991 348 170 1021 101 1640
1992 665 311 822 217 2015
1993 799 206 752 100 1857
1994 1088 512 809 103 2512
1995 1234 971 579 152 2936
1996 1069 508 471 182 2230
1997 1028 653 473 255 2409
1998 879 598 405 273 2155
1999 1047 609 448 185 2290
2000 351 227 213 120 910
2001 425 369 270 158 1222
2002 369 543 276 139 1327
2003 131 306 333 108 878
2004 289 494 588 126 1497
2005 397 752 799 208 2157
2006 462 731 571 201 1964
2007 302 1059 496 146 2003
2008 26 561 234 41 861


Figure 5.4.34.3.1. Nephrops in FU16 (Porcupine Bank). Landings in mean sizes by sex and country and in mean size in the catch for the Porcupine survey.


Figure 5.4.34.3.2. Nephrops FU16 (Porcupine Bank). Trends in the percentages of the sampled male Nephrops landings <32 mm carapace length (a possible recruitment proxy) and >50 mm carapace length.


Figure 5.4.34.3.3. Nephrops FU16 (Porcupine Bank). Trends in an exploitation proxy for this stock. This is derived from the slope of the length–frequency for male Nephrops between carapace lengths of 41–56 mm which are considered fully selected in the fishery.


Figure 5.4.34.3.4. Nephrops FU16 (Porcupine Bank). Changes in biomass and number stratified indices during Porcupine Survey time-series (2001–2008). Boxes mark parametric standard error of the stratified abundance index. Lines mark bootstrap confidence intervals (a = 0.80, bootstrap iterations = 1000).


Figure 5.4.34.3.5. Nephrops FU 16 (Porcupine Bank). Effort and lpue trends for fleets.


Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of exploitation boundaries in relation to precautionary considerations that catches in 2010 should be reduced to the lowest possible level.


Table 5.4.34.3.1. Nephrops on Porcupine Bank (FU 16). Single-stock exploitation boundaries (advice), management and landings.
Year ICES advice ICES advice for Porcupine Bank (FU16)

Recommended

Landings VIIbcjk1

Official

Landings
FU16 2

1987       2.5
1988       2.4
1989       2.1
1990       1.9
1991       1.6
1992     3.8 2.0
1993     ~4.0 1.9
1994     ~4.0 2.5
1995     ~4.0 2.9
1996     4.0 2.2
1997     4.0 2.4
1998     4.0 2.2
1999     4.0 2.3
2000     4.0 0.9
2001     4.0 1.2
2002     4.44 1.3
2003     4.44 0.9
2004 Restrict landings to 2000–2002 levels   3.3 1.5
2005 Restrict landings to 2000–2002 levels   3.3 2.2
2006 Restrict landings to 2000–2002 levels   3.3 2.0
2007 Constrain effort at recent levels   -- 2.0
2008 Constrain effort at recent levels   -- 0.9
2009 No increase in effort, and average landings (2000-2003) < 1.0    
2010 Reduce catches to lowest possible level 0    

Weights in ‘000t

1 Previously ICES gave combined advice for FUs 16, 17, 18, and 19, and Other rectangles in this area.

2 This includes inshore rectangles along the southern and southeastern coast of Ireland.



Management
Management unit: Yes

Management Advice

Management considerations

ICES advises that management should be at a smaller scale than the ICES Subarea VII. Management at the Functional Unit level could provide the controls to ensure that catch opportunities and effort are at the same scale as the resource.

Nephrops on the Porcupine Bank are fished in relatively deep waters occurring over a fairly widespread area at relatively low abundance. Given the sedentary nature of Nephrops populations closed areas may be an appropriate management tool to recover the stock.

Productivity of deep-water Nephrops stocks is generally lower than those on the shelf although individual Nephrops grow to relatively large sizes and attain high market prices. Other deep-water Nephrops stocks off the Spanish and Portuguese coast have collapsed and have been subject to recovery measures for several years, e.g. FUs 25, 26, 27 and 31.
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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