Testing Nordmøre grids on the target and by-catch species of the commercial bottom trawl fishery in the Gulf of Cadiz


  • Mariángeles Gamaza IEO, Instituto Español de Oceanografía
  • Ignacio Sobrino IEO, Instituto Español de Oceanografía
  • Karim Erzini Centre of Marine Sciences (CCMAR), University of Algarve




by-catch, Gulf of Cadiz, deep-water rose shrimp, Nordmøre grids, selectivity, trawl fisheries


Sorting grids have been tested worldwide in trawl fisheries. Here we report upon the first trials performed using Nordmøre sorting grids with four different bar spacings in the trawl fisheries of the Gulf of Cadiz targeting crustaceans as the main resource. A total of 288 valid hauls and 67 commercial species were caught. Escapement and escape size selectivity were evaluated for the most important target and by-catch species. A decrease in the percentage of biomass escape was recorded with increasing grid spacing for the two target species, deep-water rose shrimp (Parapenaeus longirostris) and Norway lobster (Nephrops norvegicus), from 24% to 8% for the former and from 86 to 9% for the latter, with a 15-mm and 30-mm grid respectively. In general, high escape rates were found for most finfish and cephalopods. For hake (Merluccius merluccius), as the main by-catch species, the results showed an escape rate decreasing from 96% to 71% as the bar spacing increased. Our findings suggest the 30-mm grid would be effective for the deep-water crustacean trawlers but different mitigation measures will be required for other métiers in the multispecies trawl fishery of the Gulf of Cadiz.


Download data is not yet available.


Anonymous. 2005. Estudio de los parámetros biológicos (crecimiento y reproducción) de diversas especies de interés pesquero en aguas del Golfo de Cádiz y Sur-Mediterráneo. Consejería de Agricultura y Pesca, Junta de Andalucía Inf. Cient.

Akaike H. 1974. A new look at the statistical model identification. IEEE Trans. Autom. Contr. AC-19: 716-722. http://dx.doi.org/10.1109/TAC.1974.1100705

Broadhurst M. K. 2000. Modifications to reduce by-catch in prawn trawls: A review and framework for development. Rev. Fish. Biol. Fish. 10: 27-60. http://dx.doi.org/10.1023/A:1008936820089

Campos A., Fonseca P. 2003. Selectivity of diamond and square mesh cod ends for horse mackerel (Trachurus trachurus), European hake (Merluccius merluccius) and axillary seabream (Pagellus acarne) in the shallow groundfish assemblage off the south west coast of Portugal. Sci. Mar. 67: 249-260.

Campos A., Fonseca P., Erzini K. 2003. Size selectivity of diamond and square mesh cod ends for four by-catch species in the crustacean fishery off the Portuguese south coast. Fish. Res. 60: 79-97. http://dx.doi.org/10.1016/S0165-7836(02)00061-9

Catchpole T.L, Revill A.S. 2007. Gear technology in Nephrops trawl fisheries. Rev. Fish. Biol. Fish. 18 (1): 17-31. http://dx.doi.org/10.1007/s11160-007-9061-y

Coll M., Carreras M., Cornax M.J., et al. 2014. Closer to reality: Reconstructing total removals in mixed fisheries from Southern Europe. Fish. Res. 154: 179-194. http://dx.doi.org/10.1016/j.fishres.2014.01.013

Ercoli R., Izzo A., Salvini L., et al. 2001. Experiencias de selectividad en los copos de las redes de arrastre y desarrollo de dispositivos selectivos con grillas en la pesquería argentina. El Mar Argentino y sus recursos pesqueros. INIDEP Doc. Cient. 3: 121-478.

Fonseca P., Campos A., Larsen R.B., et al. 2005. Using a modified Nordmore grid for by-catch reduction in the Portuguese crustacean trawl fishery. Fish. Res. 71: 223-239. http://dx.doi.org/10.1016/j.fishres.2004.08.018

González-Garcés A., Pereiro F.J. 1994. Present stage of knowledge of hake populations which live on the continental shelf of the Atlantic and Mediterranean parts of the European Union, with especial attention to the Iberian Peninsula. Private publication. Instituto Espa-ol de Oceanografía. pp. 327.

Isaksen B. 1990. Grid sorting system to reduce by-catch of fish in shrimp trawl. ICES Fish. Tec. 8.

Isaksen B., Valdemarsen J.W., Larsen R.B., et al. 1992. Reduction of fish by-catch in shrimp trawl using a rigid separator grid in the aft belly. Fish. Res. 13: 335-352. http://dx.doi.org/10.1016/0165-7836(92)90086-9

Jiménez M.P., Sobrino I., Ramos F. 2004. Objective methods for defining mixed-species trawl fisheries in Spanish water of the Gulf of Cádiz. Fish. Res. 67: 195-206. http://dx.doi.org/10.1016/j.fishres.2003.09.048

Ramos F., Sobrino I., Jiménez M.P. 1997. Cartografiado temática de los caladeros de la flota de arrastre en el Golfo de Cádiz. Dirección general de investigación y formación agraria. Servicio de publicaciones y divulgación. Junta de Andalucía. 84-87564-96-8.

Sardà F., Bahamón N., Molí B., et al. 2006. The use of a square mesh codend and sorting grids to reduce catches of young fish and improve sustainability in a multispecies bottom crawl fishery in the Mediterranean. Sci. Mar. 70(3): 347-353.

Sobrino I. 1998. Biología y pesca de la gamba blanca (Parapenaeus longirostris, Lucas 1846) en el Atlántico nororiental. Ph.D. thesis. Univ. Sevilla. Spain: 218 pp.

Sobrino I., García T. 2007. Reproductive aspects of the deep-water rose shrimp Parapenaeus longirostris (Lucas,1846) in the Gulf of Cadiz (southwestern Iberian Peninsula). Bol. Inst. Esp. Oceanogr. 23(1-4): 57-71.

Sobrino I., Jiménez M.P., Ramos F. 1993. Resultados preliminares sobre la distribución y abundancia de la merluza europea (Merluccius merluccius L.) en la región suratlántica espa-ola. En: González-Garcés A., Pereiro F.J. Estado actual de los conocimientos de las poblaciones de merluza que habitan la plataforma continental atlántica y mediterránea de la Unión Europea con especial atención a la Península Ibérica. Vigo : Instituto Espa-ol de Oceanografía, pp. 281-304.

Sobrino I., Jiménez M.P., Ramos F., et al. 1994. Descripción de las pesquerías demersales de la Región Suratlántica Espa-ola. Inf. Tec. Inst. Oceanog. 151.

Sobrino I., Ramos F., Jiménez M.P., et al. 1996. Study on the Spanish trawling fleet components and mapping of resources exploited by this fleet off the Gulf of Cadiz. Final Report.Cooperative Project No. IEO/EC-DG XIV/C/1/STUDY/94/029.

Tokai T. 1997. Maximum likelihood parameter estimates of a mesh selectivity logistic model through SOLVER on MS-Excel. Bull. Jpn. Soc. Fish. Oceanogr. 61 (3): 288-298.

Tokai T., Omoto S., Sato R., et al. 1996. A method of determining selectivity curve of separator grid. Fish. Res. 27: 51-60. http://dx.doi.org/10.1016/0165-7836(95)00471-8

Valdermarsen J.W., Lehmann K., Riget F., et al. 1993. Grid devices to select shrimp size in trawls. ICES Stat. Meet. Fish. capt. Comm. CM 1993/B35.

Valentinsson D., Ulmestrand M. 2005. Mandatory use of species-selective grids in the Swedish Nephrops trawl fishery on national waters—Experiences after one year with new regulations. Inst. Mar. Res. Rep. Sweden, Lysekil.

Wileman D.A., Ferro R.S.T., Fonteyne R., et al. 1996 Manual of methods of measuring the selectivity of towed fishing gear. ICES Coop. Res. Rep. 215.



How to Cite

Gamaza M, Sobrino I, Erzini K. Testing Nordmøre grids on the target and by-catch species of the commercial bottom trawl fishery in the Gulf of Cadiz. scimar [Internet]. 2015Dec.30 [cited 2021Mar.7];79(4):465-77. Available from: http://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1602




Similar Articles

You may also start an advanced similarity search for this article.

Most read articles by the same author(s)