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Shrimp - Skagerrak and Norwegian Deeps, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Shrimp - Skagerrak and Norwegian Deeps, 2008
Fact Sheet Citation  
Shrimps (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deeps)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Northern prawn, fr - Crevette nordique, es - Camarón norteño, ru - Креветка северная
Geographic extent of Shrimp - Skagerrak and Norwegian Deeps
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.  

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

Regulations and their effects

The main regulation tool is a TAC, which is not fully fished by all countries. High-grading (discarding of medium-sized low-value shrimp) is documented for the Swedish fishery and in most recent years discarding of small shrimp has been documented also for the Norwegian fishery. The estimated discards are included in the total catch.. Swedish high-grading is reported to be due to quota limitations. Discarding of small sized shrimp may also take place in the Danish fishery, but no data are available at present. Minimum legal mesh size is 35 mm, but an increasing number of shrimp vessels apply up to 45 mm in the cod-end.

Changes in fishing technology and fishing patterns

The number of Danish shrimp vessels has decreased from 191 in 1987 to only 11 in 2008. Mainly small trawlers have left the fishery, with the mean size of the vessels having increased from 20 to 26 m. The efficiency of the gear in the Danish shrimp fishery has increased due to twin trawl technology and increasing trawl sizes.

In the Norwegian fleet the number of small vessels (10–10.99 m) has increased, and this size class is now the most numerous, as a license to fish is not required for vessels <11 m. In contrast to previous years, quantitative information on gear changes in the Norwegian fleet has become available from interviews with ship owners.

The Swedish fishery has shown an increasing use of trawls equipped with sorting grids.

Impacts of the environment on the fish stock

The natural mortality for Pandalus borealis in Divisions IIIa and IVa East is likely to be substantially higher than the fishing mortality and is dependent on the abundance of predators.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

The assessment is based on the evaluation of both Danish (since 1987) and Norwegian (since 2000) standardized lpues, standardized effort, and indices of recruitment and biomass from Norwegian survey (since 2006).

Uncertainties in the assessment

The assessment is indicative of trends only.

The estimate of Danish lpue is based on fishing trips where the landing value of Pandalus catches was at least 50% of the landing value of all species. This threshold was selected to ensure the exclusion of trips where Pandalus landings can be considered as bycatch rather than a target species.

Comparison with previous assessment and advice

Since 2006 the assessments have been only qualitative and based on trends in standardized LPUEs and abundance indices from surveys. In 2006 and 2007 only Danish lpues were used in the assessment due to low coverage of the Norwegian logbook data. However, since 2008 assessment the Norwegian lpue data have been included in the assessment.

This year advice basis is based on the abundance indices from Norwegian survey which indicates a decrease since 2007.
Overall Assessment Results


Figure 6.4.16.1 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Landings, TAC, and catches as estimated by ICES.


Figure 6.4.16.2 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Danish and Norwegian standardised LPUEs. Error bars are standard errors. Danish 2009 data are not included due to problems with data extraction. Dotted line shows the Danish 1987-2009 mean: 1.01. The Norwegian mean for 2000-2009 is estimated to be: 0.88.


Figure 6.4.16.3 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Biomass indices estimated from Norwegian surveys.. Results are not comparable because different methodology was used.. Standard errors (error bars) estimated for 2004–2009 surveys. Survey 1: October/November 1984–2002 with Campelen-trawl; Survey 2: October/November 2003 with shrimp trawl 1420 (not shown); Survey 3: May/June 2004–2005 with Campelen trawl; Survey 4: February 2006–2009 with Campelen trawl.


Figure 6.4.16.3 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Recruitment indices from Norwegian shrimp survey The recruitment index is calculated as the abundance of age 1 shrimp (the first mode in the length–frequency distribution).


Table 6.4.16.2 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Bycatch in the shrimp fishery in 2008. Combined data from Danish and Swedish logbooks and Norwegian landings (tonnes).
Species:

Subdiv. IIIa

no grid

Subdiv. IIIa

grid

Subdiv. IVa East

no grid

  Total % of total catch Total % of total catch Total % of total catch
Pandalus 9606 86.9 634 99.3 2126 77.0
Norway lobster 52 0.5 3 0.5 76 2.8
Angler fish 52 0.5 0 0.0 74 2.7
Whiting 9 0.1 0 0.0 5 0.2
Haddock 78 0.7 0 0.0 24 0.9
Hake 45 0.4 0 0.0 41 1.5
Ling 45 0.4 0 0.0 31 1.1
Saithe 510 4.6 0 0.0 233 8.4
Witch flounder 95 0.9 0 0.0 4 0.1
Norway pout 0 0.0 0 0.0 0 0.0
Cod 399 3.6 0 0.0 101 3.7
Other market fish 164 1.5 0 0.0 46 1.7
 


Table 6.4.16.3 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Landings, discards, catches(in tonnes) as estimated by ICES and TACs.
Year Denmark Norway *) Sweden *) Total landings Est. SW high grading Est. NO discards TAC Est. catch
1970 1102 1729 2742 5573        
1971 1190 2486 2906 6582        
1972 1017 2477 2524 6018        
1973 755 2333 2130 5218        
1974 530 1809 2003 4342        
1975 817 2339 2003 5159        
1976 1204 3348 2529 7081        
1977 1120 3004 2019 6143        
1978 1459 2440 1609 5508        
1979 1062 3040 1787 5889        
1980 1678 4562 2159 8399        
1981 2593 5183 2241 10017        
1982 3766 5042 1450 10258        
1983 1567 5361 1136 8064        
1984 1800 4783 1022 7605        
1985 4498 6646 1571 12715        
1986 4866 6490 1463 12819        
1987 4488 8343 1322 14153        
1988 3240 7661 1278 12179        
1989 3242 6411 1433 11086        
1990 2479 6108 1608 10195        
1991 3583 6119 1908 11610        
1992 3725 7136 2154 13015     15000  
1993 2915 7371 2300 12586     15000  
1994 2134 6813 2601 11548     18000  
1995 2460 8095 2882 13437     16000  
1996 3868 7878 2371 14117     15000  
1997 3909 8565 2597 15071     15000  
1998 3330 9606 2469 15406     18800  
1999 2072 6739 2445 11256     18800  
2000 2371 6444 2225 11040     13000  
2001 1953 7266 2108 11327 375   14500 11702
2002 2466 7703 2301 12470 908   14500 13378
2003 3244 8178 2389 13811 868   14500 14679
2004 3905 9544 2464 15913 1797   15690 17710
2005 2952 8959 2257 14168 1483   15600 15651
2006 3061 8669 2488 14218 1186   16200 15404
2007 2380 8686 2445 13511 1124 526 16600 15161
2008 2259 8260 2479 12998 2003 1408 16300 16409
                 
*) Swedish and Norwegian landings have been corrected for loss in weight due to boiling.  

Reference Point
 

No reference points have been established for this stock.
Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of exploitation boundaries in relation to precautionary considerations that the total landings from IIIa and IVa East in 2010 should not be increased above the 2008 level of 13 000 t (corresponding to an estimated catch level of 15000-16000 t).


Table 6.4.16.1 Northern shrimp (Pandalus borealis) in Division IIIa and Division IVa East (Skagerrak and Norwegian Deep). Single stock exploitation boundaries (advice), management and catch.
Year

ICES

Advice

Predicted lndgs corresp. to advice1 Predicted lndgs corresp. to single-stock exploitation boundaries 1

Agreed TAC

Division IIIa

Agreed TAC

Div. IIa +

IIIa + IV

Discards. Landings ICES catch Disc + Landings
1987 Not assessed         0.7 14.2 14.9
1988 Catches significantly below 1985–19863         0.8 12.2 12.9
1989 No advice     3.11   1.1 11.1 12.1
1990 F as F(pre-85)3; TAC3; No increase in F4; TAC4 10.0   2.751   1.2 10.2 11.4
1991 No increase in F; TAC 12.0   8.55   0.5 11.6 12.1
1992 Within safe biological limits 152   10.50 15.0 0.5 13.0 13.6
1993 Within safe biological limits 132   10.50 15.0 0.9 12.6 13.5
1994 Within safe biological limits 192   12.60 18.0 0.2 11.5 11.7
1995 Within safe biological limits 132   11.20 16.0 0.3 13.4 14.5
1996 No advice 112   10.50 15.0 0.3 14.1 14.5
1997 No advice 132   10.50 15.0 1.0 15.1 16.1
1998 No increase in F; TAC 192   13.16 18.8 0.4 15.4 15.8
1999 Maintain F 192   13.16 18.8 0.6 11.3 11.9
2000 Maintain F <11.52   9.10 13.0 0.7 11.0 11.5
2001 Maintain F 13.4   10.15 14.5 0.746 11.3 11.7
2002 Long-term average landings 12.6   10.15 14.5 0.96 12.5 13.4
2003 Maintain F 14.7   10.15 14.5 0.96 13.8 14.7
2004 No increase in F 5   15.35 10.71 15.7 1.86 15.9 17.7
2005 No increase in catch above recent level   ~135 10.71 15.6 1.56 14.2 15.7
2006 No increase in catch above recent level   ~13.55 11.2 16.2 1.26 14.2 15.3
2007

No increase in landings above recent level

  ~14.05 11.62 16.6 1.76 13.5 15.2
2008

No increase in landings above recent level

  ~155 11.62 16.3 3.4 13.0 16.4
2009 Same advice as last year   ~155 11.62 16.6      
2010

No increase in landings above 2008 level

  ~135          

Weights in ‘000 t.

1 EU zone only. 2 Catch at status quo F.

3 Division IIIa. 4 Division IVa East.

5 Single-stock boundaries and the exploitation of this stock should be conducted in the context of mixed f6 6Discards due to Swedish high-grading and Norwegian discards of non-marketable shrimp <15 mm CL (from 2007)

isheries protecting stocks outside safe biological limits.



Management
Management unit: Yes

Management Objectives

There are no explicit management objectives for this stock.
Management Advice

Management considerations

Following the EU Commission consultation paper on TACs for 2010 (COM(2009) 224, 12 May 2009) this stock would be categorised based on the average stock biomass estimated in the last two years compared to the average of the three preceding years. The relative stock biomass index shows a decrease of 38% from 2006 to 2009. According to EU rules, this should result in a 15% decrease of TAC (14 110 t).

Sorting grids should be mandatory in this fishery in all areas to minimize by-catch. When sorting grids are not used, by-catch species may constitute up to 20% of the landed catch (Table 6.4.16.2) of which saithe and cod are the dominating species. In addition, the shrimp survey indicates that deep-sea species such as Argentines, roundnose grenadier, rabbitfish, and sharks are frequently caught in shrimp trawls in the deeper parts of Skagerrak and the Norwegian Deep. A narrow bar spacing in sorting grids would reduce by-catches of juvenile fish.

The management of this stock should address the discarding of small shrimps, which occurs mainly due to high-grading as a consequence of restrictive TACs. At present the estimated discards amount to around 20% of the total catch (Table 6.4.16.3).

All vessels, including the increasing number of small Norwegian vessels (<11 m), should be required to fill in and deliver logbooks.

Impacts of fisheries on the ecosystems

Shrimp is an important part of the diet for many predators including cod, saithe, and other species.
Biological State and Trend
Exploitation rate: Unknown
Abundance level: Unknown


Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to highest yield

Fishing mortality in relation to

agreed target

Comment
Unknown Unknown Undefined NA  



In the absence of defined reference points, the state of the stock cannot be evaluated with regard to biological reference points. The state of the stock is uncertain but abundance indices from Norwegian survey indicate a decrease since 2007. The landings per unit of effort (lpue) indices indicate that the stock has been fluctuating without any clear trends since the mid-1990s. Both Biomass and recruitment (1 year old) indices estimates from the Norwegian survey indicate a decrease since 2007.
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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