Basic principle of exploitation Shared stocks in the Baltic

1. Management of shared stocks,Baltic casebyJan HorbowyBaltic Sea regional participatory meeting, ComFishGdynia, 24-26 April, 2012

2. Plan • Basic principle of exploitation • Shared stocks in the Baltic • Procedures of assessment and management • Example of ICES advice

3. Sustainable fishery Main goal of management: sustainable fishery, fishery which may be repeated year after year, stock biomass does not decline due to fishery, may vary due to environmental effects • At each biomass there is catch level, equal to yearly surplus* productionof stock, which will not result in biomass change • The maximum of such catches is MSY (maximum sustainable yield) • MSY main goal of EU fisheries, (Common Fishing Policy) *surplus production= total production – loses due to natural mortality

4. Norwegian spring-spawning herring, eg. of stock collapse • Information from fishery is not sufficient to protect stock from overfishing: • collapse of stock at end of 1960s • high catches at low stock size • rebuilding of stock after ca. 20 years red line=biomass blueline=catch

5. Main fish stocks in the Baltic Cod: western (sub. 22-24) eastern (sub. 25-32) Herring: western (sub. 22-24) central(sub. 25-29,32) Bothnian Sea (sub. 30) BothnianGulf(sub. 31) Gulf of Riga Sprat: whole Baltic (sub. 22-32) Flatfishes (several stocks) Salmon & trout All stocks are exploited by at least two (often much more) countries

6. Selected features of fish stocks in the Baltic • All stocks are exploited by at least two (often much more) countries • Fish undertake migrations, some very long known from • - tagging (herring and cod) • - parasitic infection (herring) • Usually no country has fishery and biological data extensive enough for assessment and management (some exceptions) • Thus: • The need for international cooperation in stock assessment & management • To assess the stock we need data fishery and biological data from all / most countries exploiting the stock • To manage the stock we need scientific advice • ICES (Intern. Council for the Explor. of the Sea) – main advisory body of EU and member countries

7. Data and procedures for stock assessment Fishery dependent data a. catch characteristics (structure, volume, age & size distribution) b. catch per effort (CPUE). Fishery independent data c. stock size from surveys (often relative), d. biological data: natural mortality, growth rate, maturity, stomach contents. Model matematyczny (różny stopień komplikacji, od 1 do kilkuset równań) Mathematical model: from simple equation to hundreds of complex equations

8. Procedures for stock assessment and management National Marine Institutes Collection, compilation and analysis of data ICES. Advice Drafting Groups Formulation of advice on fisheries, Advising on TAC ICES Working Groups Data compilation and analysis, stock assessment & catch projection • ICES Advice: • Several stages • Involvement of stakeholders • Quality control • Transparency • Independency ICES, ACOM Formulating final ICES advice ICES, Review Groups (with external experts) Verification of data, methods, and calculations

9. Baltic Fisheries Assessment Working Group, WGBFAS

10. Acoustic surveys in the Baltic • Two surveys: • Herring survey, October • Sprat survey, May • Internationally coordinated • Agreed methodoogy Areas surveyed by countries

11. Bottom trawl surveys in the Baltic • Two surveys focussed on cod & flatfishes: • winter survey, Feb-March • autumn survey, November • Internationally coordinated, • standard gear, TV3 small & large Randomly selected trawling positions in the Baltic

12. TAC allocation to countries: - usually basing on historical shares in the catches

13. Thank you