The effect on juvenile haddock by-catch of changing cod-end twine thickness in EU trawl fisheries
Kynoch, R.J.; Ferro, R.S.T.; Zuur, G. (1999). The effect on juvenile haddock by-catch of changing cod-end twine thickness in EU trawl fisheries. Mar. Technol. Soc. J. 33(2): 61-72
In: Marine Technology Society Journal. Marine Technology Society (MTS): Washington, D.C.. ISSN 0025-3324; e-ISSN 1948-1209, more
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| Authors | | Top |
- Kynoch, R.J.
- Ferro, R.S.T.
- Zuur, G.
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| Abstract |
The selectivity of North Sea haddock (Melanogrammus aeglefinus) was measuredfor 100 mm mesh trawl cod-ends made of three different twines: 4 mm double twineused commercially until the introduction of thicker twines during the 1990's; 6 mmdouble twine and 8 mm single twine proposed by the European Commission asmaximum thicknesses starting in January 2000. A significant difference in selectivitywas found between the 4 mm double twine and the two thicker, stiffer twines. The50% retention length was increased by almost 4 cm when using the thinner twine.Models of the selectivity of these cod-ends have been developed, taking intoaccount small mesh size differences and using catch size as a variable and sea stateand twine size as categorical variables. The benefits of using a thinner twine cod-endare illustrated by showing the effect on the catch of juvenile and marketable fish froma typical North Sea population of haddock. The potential increases in survival of the2+ and 3+ year classes of such a haddock stock are estimated to be 17% and 12%respectively. |
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