Fishes of the Baltic Sea - counted once yearly

Project

Gefangene Fische werden nach Art und Größe sortiert. (c) Thuenen-Institut/ Daniel Stepputtis
Gefangene Fische werden nach Art und Größe sortiert. (© Thuenen-Institut/ Daniel Stepputtis)

DCF (Data Collection Framework): Assessing the stock development for cod, herring, flounder and sprat in the Baltic within the frame of ICES assessment working groups

What is the status of a commercially used fish stock in the Baltic Sea – and how does it develop? Given that most stocks are “shared stocks”, this question is raised annually and can only be answered in cooperation with other Baltic Sea countries. The answer is highly important for both fishing industry and anglers, and conservationist.

Background and Objective

The recruitment of fish stocks is subject to strong natural variation. An extremely strong year class allows the fisheries to prosper for years, whereas, if recruitment fails, the fisheries can be severely hit. Therefore, the status of commercially used fish stocks is usually assessed on a yearly basis. Thus, changes – both upwards and downwards – can be anticipated and taken into account by the fisheries management.

In the Baltic Sea, each spring the fisheries-dependent and fisheries-independent data are compiled. This takes place within the scope of “assessment” working groups of the International Council for the Exploration of the Sea (ICES). The ICES headquarter is in Copenhagen. There German experts participate in an international effort to calculate and estimate the stock status of the different commercially used fish stocks of the Baltic Sea.

The commercially used fish stocks in the Baltic Sea with importance for the German fisheries are cod, herring, sprat and the flatfishes flounder, plaice, dab, turbot and brill.

Important for us is the participation in the „Herring Assessment Working Group for Herring South of 62°N“ (HAWG) and „Baltic Fisheries Assessments Working Group“ (WGBFAS). These tasks are conducted within the EU-cofinanced project „Data Collection Framework“ (DCF).

Approach

The stock assessment uses fisheries-dependent and fisheries-independent data. Fisheries-dependent data are logbook information and landing slips of the commercial fisheries. These are provided by responsible control authority, the Federal Office for Agriculture and Food (BLE). These data are merged with our own samplings of the commercial fisheries. At-sea observer of the OF measure the catch and length compositions on board of German commercial fishing vessels. In addition, we purchase unsorted catch samples from fishing vessels. The samples are analysed in our laboratory using standard procedure of fishery biology. We determine important parameters such as sex, maturity and age. These biological data are then used to raise the mere landing figures from the fisheries into data that can be used in stock assessment, e.g. the number age 1, age 2, age 3 etc year old fish, discard rates etc.

Parallel to these activities, we carry out elaborate, internationally coordinated fisheries-independent monitoring programmes, such as the Baltic International Trawl Survey (BITS) tailored for demersal fishes like cod and flatfishes, or the Baltic International Acoustic Survey (BIAS) for herring and sprat. They provide a measure to collect standardized information independent from the fisheries on age and frequency distribution of fish covering the whole range of entire stocks.

The large data sets are used in stock assessment models. The data are stored in national and international data bases.

Preliminary Results

Results of the annual fisheries assessment working groups are available as freely downloadable documents (see www.ices.dk).

Thünen-Contact


Involved Thünen-Partners


Duration

Permanent task 1.2001 - 12.2018

More Information

Projekt type:
Project status: ongoing

Publikationen

hits: 19

  1. Gröhsler T, Schaber M (2014) Annex 6: Cruise reports from other acoustic surveys in the area : Annex 6a: Western Baltic acoustic survey ; Survey report for FRV "Solea" ; German Acoustic Autumn Survey (GERAS), 30 September 2013 - 19 October 2013. In: Report of the Working Group of International Pelagic Surveys (WGIPS) ; 20-24 January 2014. Copenhagen: ICES, pp 224-251
  2. Gröhsler T, Schaber M (2014) Survey Report for FRV "Solea" German Acoustic Autumn Survey (GERAS) 30 September 2013 - 19 October 2013. In: Report of the Baltic International Fish Survey Working Group (WGBIFS) : 24-28 March 2014 ; Gdynia, Poland. Copenhagen: ICES, pp 250-258
  3. Oeberst R, Gröhsler T, Schaber M, Larson N (2013) Applicability of the Separation Function (SF) in 2011 and 2012. In: Report of the Baltic International Fish Survey Working Group (WGBIFS) : 20-25 March 2013. Copenhagen: ICES, pp 399-405
  4. Oeberst R, Gröhsler T, Schaber M (2013) Applicability of the Stock Separation Function (SF) on the first period of GERAS in 1994-2004. Working Document WKPELA2. Benchmark Workshop on on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, 4 p
  5. Gröhsler T (2013) Assessment input database. In: Report of the Benchmark Workshop on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, pp 417-437
  6. Oeberst R, Gröhsler T (2013) Comparison of stock indices based on GERAS estimated with the standard procedure and by the new proposed method : Working document Baltic International Fish Survey Working Group (WGBIFS) 20-25 March 2013. Copenhagen: ICES, 9 p
  7. Gröhsler T (2013) Die Lage der Fischbestände im Skagerak/Kattegat und in der Ostsee : Stand 27.08.2013. Copenhagen: ICES, 26 p
  8. Gröhsler T, Oeberst R, Schaber M, Larson N, Kornilovs G (2013) Discrimination of western Baltic spring-spawning and central Baltic herring (Clupea harengus L.) based on growth vs. natural tag information. ICES J Mar Sci 70(6):1108-1117, doi:19.1093/icesjms/fst064
  9. Gröhsler T, Neuenfeldt S (2013) Exploration of different assessment units. In: Report of the Benchmark Workshop on Baltic Multispecies Assessments (WKBALT): 4-8 February 2013. Copenhagen: ICES, pp 249-265
  10. Gröhsler T, Neuenfeldt S (2013) Exploration of new M values derived from SMS. In: Report of the Benchmark Workshop on Baltic Multispecies Assessments (WKBALT): 4-8 February 2013. Copenhagen: ICES, pp 332-344
  11. Gröhsler T (2013) Exploration of XSA settings. In: Report of the Benchmark Workshop on Baltic Multispecies Assessments (WKBALT): 4-8 February 2013. Copenhagen: ICES, pp 314-331
  12. Gröhsler T, Oeberst R, Schaber M (2013) Implementation of the Stock Separation Function (SF) on German commercial landings. In: Report of the Benchmark Workshop on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, pp 379-386
  13. Gröhsler T, Oeberst R, Schaber M (2013) Implementation of the Stock Separation Function (SF) within GERAS in 2005-2011. Working Document WKPELA 1. Benchmark Workshop on on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, 6 p
  14. Oeberst R, Gröhsler T, Schaber M (2013) Investigations on quality of Stock Separation Function (SF). Working Document WKPELA4. Benchmark Workshop on on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, 22 p
  15. Bartolino V, Gröhsler T, Vitale F, Krischansson B, Johansson M (2013) Maturity at age in the WBSSH herring : motivation of the study and background. In: Report of the Benchmark Workshop on Pelagic Stocks (WKPELA): 4-8 February 2013. Copenhagen: ICES, pp 470-475
  16. Oeberst R, Gröhsler T (2013) Quality of age determination. Working Document WKPELA7. In Benchmark workshop on pelagic stocks (WKPELA), WBSSH 04-08 February 2013. Copenhagen: ICES, 3 p
  17. Schaber M, Gröhsler T (2013) Survey Report for FRV "Solea" 2-21 October 2012. In: Report of the Baltic International Fish Survey Working Group (WGBIFS) : Annex 8: Cruise reports of acoustic surveys BASS and BIAS in 2012. Copenhagen: ICES, pp 266-289
  18. Barz K, Gröhsler T, Zimmermann C (2013) Zustand und Entwicklung ausgewählter Fischbestände in der Ostsee: der ICES-Advice für 2014. Fischerei Fischmarkt MV 13(3):44-49
  19. Velasco A (2010) Bericht über die 629. Reise des FFS "Solea" vom 28.10. bis zum 19.11.2010. 8 p

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