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Comparing selectivity of a standard and turned mesh T90 codendduring towing and haul-back

Published online by Cambridge University Press:  05 September 2012

Niels Madsen ,
Bent Herrmann ,
Rikke Petri Frandsen  and
Ludvig Ahm Krag
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Abstract

In this study, we compared the size selectivity of a T90 codend (nettingturned by 90 degrees) with that of a standard codend made of similar netting. Sea trialswere conducted in a Norway lobster directed fishery in the Kattegat-Skagerrak area, wherethere is a need for improved selectivity because of a severe discard problem. The codendswere tested by fishing simultaneously with them in a twin trawl rig. Codend covers mountedwith Minisamplers were used, which made it possible to catch individuals escaping duringtowing and haul-back separately. Herein we proposed a model to assess the sequentialselection during towing and haul back. This model takes into account the parameterCtow, which can be interpreted as theproportion of fish that comes into contact with the codend meshes during towing and,thereby, has a chance of escape. Compared to the standard codend, the T90codend retained fewer Norway lobster both below and above the legal minimum landing size(40 mm, cephalothorax length), thereby causing a reduction of commercial catch. Thedifference was mainly due to a significantly higher escape rate during towing for theT90 codend. For plaice below minimum landing size (27 cm), theretention was slightly but significantly higher for the T90 codendcompared to the standard codend. A model developed for both codends showed that not allplaice are able to attempt escapement during the towing process. For cod, the resultsindicated an increased L50 (the length at which 50% of this species iscaught) for the T90 codend, but the effect was not statisticallysignificant, probably due to the limited number of cod retained during the sea trials. Theresults demonstrated that, for all three species, a significant proportion did escapeduring haul-back in both codends.

Keywords

DiscardTurned mesh codendDemersal trawlSize selectivityNorway lobsterNephrops norvegicusGadus morhuaPleuronectes platessaKattegat
Type
Research Article
Information
Aquatic Living Resources , Volume 25 , Issue 3 , July 2012 , pp. 231 - 240
Copyright
© EDP Sciences, IFREMER, IRD 2012

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References

Akaike, H., 1974, A new look at the statistical model identification. IEEE Trans. Automat. Contr. AC-19, 716–23. CrossRefGoogle Scholar
Catchpole, T.L., Revill, A.S., 2008, Gear technology in Nephrops trawl trawl ?sheries. Rev. Fish. Biol. Fish. 18, 17–31. Efron, B., 1982, The jackknife, the bootstrap and other resampling plans. SIAM Monograph No. 38, CBSM-NSF. CrossRefGoogle Scholar
Eigaard, O.R., Herrmann, B., Nielsen, R., 2012, Influence of grid orientation and time of day on grid sorting in a small-meshed trawl fishery for Norway pout (Trisopterus esmarkii). Aquat. Living Resour. 25, 15–26. CrossRefGoogle Scholar
Feekings, J., Bartolino, V., Madsen, N., Catchpole, T., 2012, Fishery discards : factors affecting their variability within a demersal trawl fishery. PLoS One 7(4), e36409. CrossRefGoogle ScholarPubMed
Fonteyne, R., Buglioni, G., Leonori, I., O’Neill, F.G., 2007, Review of mesh measurement methodologies. Fish. Res. 85, 279–284. CrossRefGoogle Scholar
Frandsen, R.P., Herrmann, B., Madsen, N., 2010a, A simulation-based attempt to quantify the morphological component of size selection of Nephrops norvegicus in trawl codends. Fish. Res. 101, 156–167. CrossRefGoogle Scholar
Frandsen, R.P., Herrmann, B., Madsen, N., Krag, L.A., 2011, Development of a codend concept to improve size selectivity of Nephrops (Nephrops norvegicus) in a multi-species fishery. Fish. Res. 111, 116–126. CrossRefGoogle Scholar
Frandsen, R.P., Madsen, N., Krag, L.A., 2010b, Selectivity and escapement behaviour of five commercial species in a square mesh and a diamond mesh codend. ICES J. Mar. Sci. 67, 1721–1731. CrossRefGoogle Scholar
Frandsen, R.P., Holst, R., Madsen, N., 2009, Evaluation of three levels of selective devices relevant to management of the Danish Kattegat-Skagerrak Nephrops fishery. Fish. Res. 97, 243–252. CrossRefGoogle Scholar
Fryer, R.J., 1991, A model of the between-haul variation in selectivity. ICES. J. Mar. Sci. 48, 281–290. CrossRefGoogle Scholar
Grimaldo, E., Larsen, R.B., Sistiaga, M., Madsen, N., Breen, M., 2009, Selectivity and escape percentages during three phases of the towing process for codends fitted with different selection systems. Fish. Res. 95, 198–205. CrossRefGoogle Scholar
Harris, R.R., Andrews, M.B., 2005a, Physiological changes in the Norway lobster Nephrops norvegicus (L.) escaping and discarded from commercial trawls on the West Coast of Scotland. 1. Body fluid volumes and haemolymph composition after capture and during recovery on the seabed. J. Exp. Mar. Biol. Ecol. 320, 179–193. CrossRefGoogle Scholar
Harris, R.R., Andrews, M.B., 2005b, Physiological changes in the Norway lobster Nephrops norvegicus (L.) escaping and discarded from commercial trawls on the West Coast of Scotland. II. Disturbances in haemolymph respiratory gases, tissue metabolites and swimming performance after capture and during recovery. J. Exp. Mar. Biol. Ecol. 320, 195–210. CrossRefGoogle Scholar
Harris, R.R., Ulmestrand, M., 2004, Discarding Norway lobster (Nephrops norvegicus L.) through low salinity layers – mortality and damage seen in simulation experiments. ICES J. Mar. Sci. 61, 127–139. CrossRefGoogle Scholar
Herrmann, B., 2005, Effect of catch size and shape on the selectivity of diamond mesh cod-ends : II Theoretical study of haddock selection. Fish. Res. 71, 15–26. CrossRefGoogle Scholar
Herrmann, B., Priour, D., Krag, L.A., 2007, Simulation based study of the combined effect on cod-end size selection for round fish of turning mesh 90° and reducing the number of meshes in the circumference. Fish. Res. 84, 222–232. CrossRefGoogle Scholar
Herrmann, B., Krag, L.A., Frandsen, R.P., Madsen, N., Lundgren, B., Stæhr, K.J., 2009, Prediction of selectivity from morphological conditions : Methodology and a case study on cod (Gadus morhua). Fish. Res. 97, 59–71. CrossRefGoogle Scholar
ICES, 2010, Report of the study group on Turned 90° codend selectivity, focusing on Baltic cod selectivity (SGTCOD). ICES CM 2010/FTC :05.
ICES, 2011, Report of the study group on Turned 90° codend selectivity, focusing on Baltic cod selectivity (SGTCOD), 4–6 May 2011, IMR, Reykjavik, Iceland. ICES CM 2011/SSGESST :08.
Krag, L.A., Frandsen, R.P., Madsen, N., 2008, Evaluation of a simple means to reduce discard in the Kattegat-Skagerrak Nephrops (Nephrops norvegicus) fishery : Commercial testing of different codends and square-mesh panels. Fish. Res. 91, 175–186. CrossRefGoogle Scholar
Lowry, N., Robertson, J.H.B., 1995, The effect of twine thickness on cod-end selectivity of trawls for haddock in the North Sea. Fish. Res. 26, 353–363. CrossRefGoogle Scholar
Madsen, N., 2007, Selectivity of fishing gears used in the Baltic Sea cod fishery. Rev. Fish. Biol. Fish. 17, 517–544. CrossRefGoogle Scholar
Madsen, N., Hansen, K.E., Moth-Poulsen, T., 2001, The kite cover : a new concept for covered codend selectivity studies. Fish. Res. 49, 219–226. CrossRefGoogle Scholar
Madsen, N., Hansen, K.E., Frandsen, R.P., Krag, L.A., 2012, Development and test of a remotely operated Minisampler for discrete trawl sampling. Fish. Res. 123-124, 16–20. CrossRefGoogle Scholar
Madsen, N., Moth-Poulsen, T., Lowry, N., 1998, Selectivity experiments with window codends fished in the Baltic Sea cod (Gadus morhua) fishery. Fish. Res. 36, 1–14. CrossRefGoogle Scholar
Madsen, N., Skeide, R., Breen, M., Krag, L.A., Huse, I., Soldal, A.V., 2008, Selectivity in a trawl codend during haul-back operation – An overlooked phenomenon. Fish. Res. 91, 168–174. CrossRefGoogle Scholar
Madsen, N., Frandsen, R.P., Holst, R., Krag, L.A., 2010, Development of new concepts for escape windows to minimise cod catches in Norway lobster fisheries. Fish. Res. 103, 25–29. CrossRefGoogle Scholar
Madsen, N., Valentinsson, D., 2010, Use of selective devices in trawls to support recovery of the Kattegat cod stock : a review of experiments and experience. ICES J. Mar. Sci. 67, 2042–2050. CrossRefGoogle Scholar
Manly B.F.J., 1997, Randomization, Bootstrap and Monte Carlo methods in biology – Texts in statistical science. Chapman & Hall.
Millar, R.B., 1993, Incorporation of between-haul variation using bootstrapping and nonparametric estimation of selection curves. Fish. Bull. 91, 564–572. Google Scholar
Sala, A., Lucchetti, A., Buglioni, G., 2007, The influence of twine thickness on the size selectivity of polyamide codends in a Mediterranean bottom trawl. Fish. Res. 83, 192–203. CrossRefGoogle Scholar
Shelton, P.M., Gaten, E., Chapman, C.J., 1985, Light and retinal damage in Nephrops norvegicus (L.) (Crustacea). Proc. R. Soc. Lond. B 226, 217–236. CrossRefGoogle Scholar
Sistiaga, M., Herrmann, B., Grimaldo, E., Larsen, R.B., 2010, Assessment of dual selection in grid based selectivity systems. Fish. Res. 105, 187–199. CrossRefGoogle Scholar
Tokac, A., Ozbilgin, H., Tosunoglu, Z., 2004, Effect of PA and PE material on codend selectivity in Turkish bottom trawl. Fish. Res. 67, 317–327. CrossRefGoogle Scholar
Valentinsson, D., Ulmestrand, M., 2008, Species-selective Norway lobster trawling : Swedish grid experiments. Fish. Res. 90, 109–117. CrossRefGoogle Scholar
Votier, S.C., Furness, R.W., Bearhop, S., Crane, J.E., Caldow, R.W.G., Catry, P., Ensor, K., Hamer, K.C., Hudson, A.W., Kalmbach, E., Klomp, N.I., Pfeiffer, S., Phillips, R.A., Prieto, I., Thompson, D.R., 2004, Changes in fisheries discard rates and seabird communities. Nature 427, 727–730. CrossRefGoogle Scholar
Wienbeck, H., Herrmann, B., Moderhak, W., Stepputtis, D., 2011, Effect of netting direction and number of meshes around on size selection in the codend for Baltic cod (Gadus morhua). Fish. Res. 109, 80–88. CrossRefGoogle Scholar
Wileman D.A., Ferro R.S.T., Fonteyne R., Millar R.B. (eds.), 1996, Manual of methods of measuring the selectivity of towed fishing gears. ICES Coop. Res. Rep. No. 215.