Habitat Bio
Depth Zone: Shelf (50 m - 200 m). Vertical Dist: Demersal/Benthic.
Distribution of plaice in the Baltic Sea extends eastwards to the Gulf of Gdansk and northwards to the Gotland area, but it is also found sporadically farther north. The distribution of this species is dependent on salinity.
Based on information on biology and fishery of plaice ICES decided that the plaice from Subdivisions 22 (the Belts) and 23 (the Sound), which were previously assumed to be part of the Baltic Sea stock, should be considered a separate stock unit together with Subdivision 21 (Kattegat) (ICES, 2012a).
There are indications that the spawning areas are likely to be located in the southern part of Subdivision 25 and 26, but the exact spawning locations are not known. Nursery areas are located in shallow waters down to 10 m depth.
Plaice spawn in February–March in the basins.
Geo Dist
Geo Dist: Shared between nations
Exploit
The fisheries
The fishery is mainly concentrated around Bornholm (Subdivisions 24 and 25) and is dominated by Denmark.
| Catch distribution | No information on total catch, 748 t landings (mainly trawl gear).. |
Bio Assess
Sci Advice
Based on the ICES approach for data-limited stocks, ICES advises that catches should be no more than 900 tonnes.
This is the first year that ICES is providing quantitative advice for data-limited stocks (see Quality considerations).
Results
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Figure 8.4.10.1 Plaice in Subdivisions 24–32 (Baltic Sea). Official landings (Subdivisions 24–32, in tonnes, left panel). Combined 1st and 4th quarters cpue (no./hr) (weighted average per depth stratum area), of fish equal to or larger than 20 cm, from the Baltic International Trawl Survey (BITS-Q1+Q4) in Subdivisions 24–28 (right panel, from ICES DATRAS database). Insert Image description or remove the attribute.  |
Assess Models
Quality consideration
Data collection, especially on the amount of discards, needs to be improved in order to get a better estimate of plaice catches in the Baltic Sea.
The advice is based on a combined abundance index from two surveys, used as an indicator of stock size. The uncertainty associated with the index values is not available.
The methods applied to derive quantitative advice for data-limited stocks are expected to evolve as they are further developed and validated. The harvest control rules are expected to stabilize stock size, but they may not be suitable if the stock size is low and/or overfished.
| Assessment type | Survey trends. |
| Input data | Commercial landings and survey data from Baltic International Trawl Survey (BITS-Q1+Q4). |
| Discards and bycatch | Discard data not used. |
| Indicators | None. |
| Other information | None. |
| Working group report | WGBFAS |
Management
Management unit: Yes
Management plans
No specific management objectives are known to ICES.
Sources
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. Plaice in Subdivisions 24-32 (Baltic Sea) Report of the ICES Advisory Committee, 2012. ICES Advice, June 2012.
http://www.ices.dk/committe/acom/comwork/report/2012/2012/ple-2432.pdf
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