Fishery Resources Monitoring System

Français
Sandeel - North Sea, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Sandeel - North Sea, 2008
Fact Sheet Citation  
Sandeel in Sub-area IV
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Sandeels(=Sandlances) nei, fr - Lançons nca, es - Lanzones nep, ru - Песчанковые
Geographic extent of Sandeel - North Sea
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: Shared between nations

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

Regulation of the catch by the sandeel fishery has since 2004 been based on the abundance of 1-group sandeels, estimated from an exploratory fishing in the beginning of the fishing season.

The number of Danish vessels has declined from 200 vessels in 2004 to 84 in 2009, and a 43% reduction in total kilowatt days for the same period. In 2007, the Danish industrial vessels were given individual tradable quotas (ITQ) on sandeel and this caused a change towards fewer and larger vessels. The Norwegian fleet fishing for sandeel declined from 90 to 33 vessels between 2002 and 2009.

In May 2009, ICES suggested a TAC of 400 000 tonnes on the basis of the real-time monitoring in April. The resulting TAC was not fully taken, recorded landings totalled 350 000 t.

Impacts of the environment on the fish stock

There are indications that the egg production in prey copepod species Calanus finmarchicus supports the survival of sandeel larvae, and that climate-generated shifts in the Calanus species composition lead to a mismatch in timing between food availability and the early life history of lesser sandeels (van Deurs et al., 2009).

Changes in fishing technology and fishing patterns

Sandeel is taken by trawlers using small-mesh gear. The fishery is seasonal, taking place mostly in the spring and summer. There used to be a targeted 0-group fishery in autumn (3rd quarter), but this ceased in 2004. Most of the catch consists of Ammodytes marinus, but other sandeel species are caught as well. There is a low percentage bycatch of other fish species, including species for which a TAC has been set (ICES, 2003).

Sandeel are largely stationary after settlement and there is a complex of local (sub-)stocks in the North Sea. Recruitment to individual fishing banks may not only be related to the local (sub-)stock, as some interchange between (sub-)stocks may take place during the early phases of life before settlement. The Shetland sandeel stock is assessed as a separate unit.

Concurrent with the increase in the total stock size, some areas especially in the northern North Sea with recent very low abundance have been repopulated in 2006 and 2008. Evidence however suggests that abundance following fisheries in 2008 in these areas is now again at a low level, and no sandeel fishery was allowed in the Norwegian EEZ in 2009
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

The assessment of sandeel is carried out without fisheries-independent indices of abundance. At present no scientific surveys time-series are available that can be used for the assessment.

The assessment method used is Seasonal XSA (SXSA), which allows the use of semi-annual data. As in previous assessments, effort data from the commercial fishery in the northern and southern North Sea are treated as two independent tuning fleets, separated into half-years.

Uncertainties in assessment and forecast

The major elements of recent recruitment and stock development are being captured in the assessment, but details in recent years are uncertain due to:

  • the assumption that there is a single North Sea stock;
  • lack of fisheries-independent tuning data;
  • large changes in fishing pattern in recent years; and
  • possible large changes in catch efficiency in recent years.


The assessment used to provide the stock status assumes equal weight for fleets fishing in the north and south of the North Sea. However in recent years, a decreasing proportion of the effort has been located within the north due to closures in the Norwegian EEZ. The assessment estimates are sensitive to the distribution of effort and exploratory assessments have highlighted that the most recent dynamics of SSB and F are sensitive to these assumptions. The resulting range of biomass estimates in 2009 spans Blim to above Bpa. The advice is based on the assessment procedure as used in previous years. A further evaluation of the assessment approach is needed to remedy these uncertainties.

Recruitment time-series estimates from surveys are not yet available, but the time-series are being developed. A first review of some of these data by ICES concludes that the surveys have the potential to provide indices of recruitment on both local and subarea scale. Recruitment estimates are presently based exclusively on commercial catch-at-age data.

Comparison with previous assessment and advice

The historical comparison of the advice shows a tendency to overestimate SSB and underestimate F.

The advice is similar to last year’s advice.
Overall Assessment Results


Figure 6.4.22.1 Sandeel in Subarea IV. Stock summary.


Figuer 6.4.22.2 Sandeel in Subarea IV. Stock–recruitment plot and precautionary approach plot.


Figure 6.4.22.3 Sandeel in Subarea IV. Comparison of historical performance of assessments.


Figure 6.4.22.3 Sandeel in Subarea IV. Data sampling areas.


Table 6.4.22.2 Sandeel in Subarea IV. Official landings (tonnes) by country and Subdivisions reported to ICES.


Table 6.4.22.3 Sandeel in Subarea IV. Landings (‘000 t) per country as provided by Working Group members.


Table 6.4.22.4 Sandeel in Subarea IV. Monthly landings (tonnes) by Denmark, Norway, and Scotland only, from the areas defined in Figure 6.4.22.4. Data provided by Working Group members.


Table 6.4.22.5 Sandeel in Subarea IV. Assessment summary.

Year

Recruitment

Age 0

Millions

SSB

tonnes

Landings*

tonnes

Mean F

Ages 1-2

1983 878848 1236745 530641 0.471
1984 225599 754271 750040 0.340
1985 1199288 1169916 707105 0.925
1986 622401 489853 685949 0.566
1987 198475 1638389 791050 0.440
1988 716146 1495275 1007303 0.799
1989 324068 493162 826836 0.704
1990 632191 648117 584912 0.820
1991 799404 455214 898959 0.773
1992 316352 671540 820140 0.514
1993 618012 1076253 576932 0.377
1994 865131 789593 770746 0.560
1995 355327 1027068 915042 0.439
1996 1893077 1075400 776126 0.483
1997 321517 649068 1114044 0.377
1998 382990 1675811 1000376 0.630
1999 488704 843271 718667 0.617
2000 484686 463992 692499 0.950
2001 851253 314486 858619 1.016
2002 74343 327895 806921 0.785
2003 274977 402129 309724 0.710
2004 145349 173288 359362 0.790
2005 289127 152014 171790 0.732
2006 191141 155050 286751 0.563
2007 299138 313998 203392 0.426
2008 310412 389009 322738 0.547
2009   455164 336897 0.687
2010   456000**    

* landings do not include 0-group in the first half-year

** preliminary results at the end of the fishing season


Reference Point
 


  Type Value Technical basis
Precautionary approach Blim 430 000 t The lowest observed biomass in the period 19761998.
  Bpa 600 000 t Bpa =1.4 * Blim.
  Flim Not defined.  
  Fpa Not defined.  
Targets Fy Not defined.  
(unchanged since 1999)


Scientific Advice

Single-stock exploitation boundaries

Considering the options below, ICES advises on the basis of exploitation boundaries in relation to precautionary limits that fishing grounds that are known to be commercially depleted should be closed to fishing while at non-depleted fishing grounds fishing should only be allowed in 2010 if analysis of real-time monitoring indicates that the stock can be rebuilt to Bpa by 2011

Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential and considering ecosystem effects

The management of sandeel fisheries should implement measures to prevent depletion of local aggregations, particularly in areas where predators congregate.

Exploitation boundaries in relation to precautionary limits

ICES recommends that fishing grounds that are known to be commercially depleted should be closed to fishing until there is evidence from monitoring programmes that local populations have recovered. On other fishing grounds, a fishery should only be allowed in 2010 if analysis of real-time monitoring indicates that the stock can be rebuilt to Bpa by 2011.


Table 6.4.22.1 Sandeel in Subarea IV. Single stock exploitation boundaries (advice), management and catch.
Year

Single-stock exploitation boundaries / from 2004 onwards ICES

Advice

Catch corresponding to exploitation boundaries / advice TAC 3

ICES

Catch

1987 No advice1; No advice2     825
1988 No advice1; No advice2     893
1989 No advice1; No advice2     1039
1990 No advice1; No advice2     591
1991 No advice1; No advice2     843
1992 No advice1; No advice2     855
1993 No advice1; No advice2     579
1994 No advice1; No advice2     786
1995 Can sustain current F1; No advice2     918
1996 Can sustain current F     777
1997 Can sustain current F     1138
1998 Can sustain current F   1000 1004
1999 Can sustain current F   1000 735
2000 Can sustain current F   1020 699
2001 Can sustain current F   1020 862
2002 Can sustain current F   1020 811
2003 No increase in F   918 326
2004 Exploitation to be kept below level of 2003. Adjustment to be made conditional on the abundance of the 2003 year class - 826 362
2005 Exploitation to be kept below level of 2003. Adjustment to be made conditional on the abundance of the 2004 year class - 661 172
2006 The fishery should remain closed until information is available which assures that the stock can be rebuilt to Bpa by 2007. - 300 288
2007 The fishery should remain closed until information is available which assures that the stock can be rebuilt to Bpa by 2008. - 1734 206
2008

The fishery should only be allowed if monitoring information is available and shows that the stock can be rebuilt to Bpa by 2009.

- 4005 335
2009 The fishery should only be allowed if monitoring information is available and shows that the stock can be rebuilt to Bpa by 2010 - 400  
2010 The fishery should only be allowed if monitoring information is available and shows that the stock can be rebuilt to Bpa by 2011 -    

Weights in ‘000 t.
1 Southern stock component.
2 Northern stock component.

3 Set for zone IIIa, EC waters of Division IIa and Subarea IV.

4 EU and Norway, set at 30 June 2007.

5 EU and Norway, set at 23 July 2008.



Management
Management unit: Yes

Management Objectives

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

Management considerations

The high natural mortality of sandeel and the few year classes in the fishery make the stock size and catch opportunities largely dependent on the size of the incoming year classes.

If a real-time management using an escapement strategy is applied in 2010, the escapement target should be defined so that the SSB reaches at least Bpa in 2011. Fishing grounds that are known to be commercially depleted should be closed to fishing until there is evidence that local populations have recovered.

ICES recommends that future management should take account of the spatial structure of sandeels. Sandeel management in the North Sea is based on the assumption that there is a single stock when there is strong evidence of a number of spatially distinct (sub-)stocks. The full stock structure of sandeel in the North Sea, however, remains unclear. It is known that (sub-)stocks on the Viking/Bergen Banks, in the western North Sea off Scotland, and the (separately-managed) Shetland stock are all distinct. The present knowledge on defining (sub-)stocks off south-western Norway and in the southern North Sea is too limited to recommend specific management measures for 2010 which can take the full stock structure into account.

Impacts of fisheries on the ecosystems

Local depletion of sandeel aggregations at a distance less than 100 km from seabird colonies may affect some species of birds, especially black-legged kittiwake (Rissa tridactyla) and sandwich tern (Sterna sandvicensis), whereas the more mobile marine mammals and fish may be less vulnerable to local sandeel depletion. In the light of studies linking low sandeel availability to poor breeding success of kittiwake, all commercial fishing in the Firth of Forth area has been prohibited since 2000, except for a short-term fishery in May and June of each year for stock monitoring purposes.

A major function of sandeels in the North Sea ecosystem is the provision of food to predators, including fish, marine mammals, and seabirds. The management objectives should ensure that the stock remains high enough to provide food for predator species and prevent depletion of local aggregations, particularly in areas of predator concentration. The sandeel fishery in the area off the Scottish coast that was closed to sandeel fishery in 2000, should continue to be closed in 2010 in view of the current low productivity of the sandeel (sub-)stock in this area and to provide, as far as possible, a food supply to dependent predators. In other areas of the North Sea, avoidance of depletion at a local scale will help take account of the function of sandeels in the ecosystem.
Biological State and Trend
Exploitation rate: Undefined
Abundance level: Increased risk


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
Increased risk Undefined Undefined Undefined  



According to the most recent estimate of SSB (2009), ICES classifies the stock as being at risk of reduced reproductive capacity. Fishing mortality decreased between 2001 and 2007 and increased in 2008 and 2009, but the present absolute level is uncertain. In the absence of an F reference point, the state of the stock cannot be evaluated with regard to sustainable harvest
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
powered by FIGIS  © FAO, 2014
Powered by FIGIS
crawl