1. The turned through 90° ( T90) meshes cod-end construction - the best way for substantial reduction of bycatch and discards - Sea Fisheries Institute Gdynia, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak

2. Sea Fisheries Institute Gdynia, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Introduction The idea of such a codend construction was first presented in 1993 at the Annual Science Conference of the ICES in Dublin and then published. The investigations on characteristics of selective cod-ends with meshes turned 90  (T90) have been carried out by Sea Fisheries Institute, Gdynia, Poland since 1996 and then in close co-operation with vTI Institute of Baltic Sea Fisheries, Rostock, Germany (former Institute for Fishery Technology and Fish Quality, Hamburg). From year 2006, T90 codend is a legal design in the Baltic Sea cod fishery.

3. MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland COUNCIL REGULATION (EC) No 2187/2005 of 21 December 2005 for the conservation of fishery resources through technical measures in the Baltic Sea, the Belts and the Sound, amending Regulation (EC) No 1434/98 and repealing Regulation (EC) No 88/98

4. Sea Fisheries Institute Gdynia, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak The construction of the turned meshes (T90) is based on typical diamond netting but that has to be turned through 90 . Therefore, the production of netting for cod-ends with meshes turned does not require any changes in machinery or production technology in net factories. The shapes of diamond and turned through 90  meshes are presented (a - diamond, b - T90). Construction

5. T90 mesh opening calculation model where: y – mesh bar bend, l – mesh bar length, q – continuous load from hydrodynamic pressure acting on the mesh bar, the mesh bar, and and p – hydrodynamic resistance force on the mesh bar, ρ – water density, ν – water velocity, d – mesh bar thickness (diameter), c – hydrodynamic force coefficient, P – concentrated force acting on the end of the mesh bar, x – current coordinate, E – modulus of elasticity (Young’s modulus), J – moment of inertia of the mesh cross-section, f (l, q, P, x) – functions dependent on bending forces and moments set acting on the mesh bar MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 M q l P x Waldemar Moderhak Flexural rigidity Sea Fisheries Institute Gdynia, Poland

6. T90 mesh bar shape for three different twines MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland 0,000 0,005 0,010 0,015 0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,0000,0050,0100,0150,0200,025 Deviation [m] Twine "a" Twine "c" Twine "b' P PP M M M 0,055 Bend of mesh bar [m]

7. Sea Fisheries Institute Gdynia, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak where: P i – concentrated force acting on the end of the mesh bar of i-th row of meshes P 0 – initial concentrated force p i – hydrodynamic force acting on the mesh bar of i-th row of meshes Force acting on the section of netting with meshes turned 90  – T90

8. The mesh shapes of the codend, extension and belly end thickness d = 4,43 mm thickness d = 4.6 mm thickness d = 3,55 mm Waldemar Moderhak MariFish Work Package7Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland codend extension belly

9. Waldemar Moderhak Shapes of codend and extension T90 made of the same netting mesh opening 109,9 mm, twine thickness 5,0/4,35 mm MariFish Work Package7Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

10. Waldemar Moderhak mesh opening 109,9 mm, twine thickness 5,0/4,35 mm mesh opening 107,3 mm, twine thickness 3,5/3,30 mm – double twine Shapes of codend and extension T90 made of different netting: MariFish Work Package7Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

11. Selection curves for L 50 =38 cm and four different SR MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland

12. Selectivity investigation of the T90 codend 08 – 09.2006 Polish investigations MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland

13. Length distribution of cod caught with a T90 codend – 12.2006 Polish investigations MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland

14. Selectivity investigation (total) – CODENDS and COVER – German investigations MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

15. Selectivity investigation – CODENDS - German investigations MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

16. Selectivity investigation - COVER – German investigations MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

17. Selectivity curves of four different codends German study - SOLEA April 2008 MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland MO = 112,4 mmMO = 112,9 mm MO = 109,0 mm MO = 112,9 mm

18. T90 codend shape - lifting strap too short – study of the Academy of Agriculture, Szczecin, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

19. Icelandic commercial T90 codend with catch MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland Sveinn Hjalmarsson

20. T90 codend in action - German investigation, CLUPEA - MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

21. T90 codend in action - German investigation, CLUPEA - MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland

22. Advantages and disadvantages of the T90 codends MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland Advantages: - very good selective and protective properties (sharp selective curve) - retain small number of fish juveniles - small by-catch of other rounded fishes - by-catch of flatfish comparable to that retained by diamond cod-end constructions - better fish condition and thus better survive rate of fishes - better quality of fish caught - environmentally friendly fishing - “clear” fishing, less work for a crew - less fuel consumption and in consequence less air pollution - improved catch abilities - simple construction - low price of turned (T90) cod-end - stability during whole towing - better breaking strength of turned netting - easy netting availability -very difficult to manipulate to reduce selectivity Disadvantages: - not recognised yet

23. MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Sea Fisheries Institute Gdynia, Poland Conclusion It may be stated that cod-end with meshes turned 90  (T90) can introduce a new level of selectivity, fish protection and substantial reduction of by-catch and discards in commercial fisheries. General idea of the turned (T90) cod-ends can be applied for designing/constructing other T90 cod-ends, with appropriate mesh sizes for particular fish species for proper protection of these fish species.

24. Thousands of herring meshed in diamond belly netting, during cod fishing - T90 belly demand !! - MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Sea Fisheries Institute Gdynia, Poland Waldemar Moderhak

25. Sea Fisheries Institute Gdynia, Poland MariFish Work Package 7 Meeting Norwich, UK June 12 - 13, 2008 Waldemar Moderhak Thank you for your attention