Scientia Marina, Vol 77, No 1 (2013)

An analysis of fishing gear competition. Catalan fisheries as case studies

Jordi Lleonart
Institut de Ciències del Mar, CSIC , Spain

Francesc Maynou
Institut de Ciències del Mar, CSIC , Spain

Jordi Salat
Institut de Ciències del Mar, CSIC , Spain


An asymmetric index was developed to measure the competition relationships among fishing fleets (or gears or métiers) in a multispecies fishery. This index can be used to measure the degree of dominance of each fleet and its level of independence from competition. To illustrate the concepts, the index is applied to two case studies using two datasets, both from Catalonia, NW Mediterranean. The results show that in both case studies the dominance of bottom trawl over most other gears (especially small-scale ones) is evidenced and quantitatively measured. Bottom trawl is also highly independent of the others. Purse seine appears to be quite independent, but not dominant over the other gears. A practical use of these asymmetric indices is to assist fisheries managers in the decision-making process to optimize the allocation of fishing effort, including energy efficiency, and to reduce environmental impact.


gear competition; asymmetric index; Mediterranean fisheries

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Aldebert Y., Recasens L. 1996. Comparison of methods for stock assessment of European hake Merluccius merluccius in the Gulf of Lions (Northwestern Mediterranean). Aquat. Living Resour. 9: 13-22.

Aldebert Y., Recasens L., Lleonart J. 1993. Analysis of gear interactions in a hake fishery: the case of the gulf of Lions (NW Mediterranean). Sci. Mar. 57: 201-217.

Coppola, S.R. 2006. Inventory of artisanal fishery communities in the Western and Central Mediterranean. Studies and Reviews. General Fisheries Commission for the Mediterranean. No. 77. Rome FAO, 82 pp.

Demestre M., Sbrana M., Alvarez F., Sánchez P. 1997. Analysis of the interaction of fishing gear in Mullus barbatus fisheries of the Western Mediterranean. J. Appl. Ichthyol. 13: 49-56.

Erzini K., Gonçalves J.M.S., Bentes L., Lino P.G., Ribeiro J., Stergiou K.I. 2003. Quantifying the roles of competing static gears: comparative selectivity of longlines and monofilament gill nets in a multi-species fishery of the Algarve (southern Portugal). Sci. Mar. 67(3): 341-352

Gallopín G.C. 1972. Trophic similarity between species in a food web. Am. Midl. Nat., 87(2): 336-345.

Griffiths R.C., Robles R., Coppola S.R., Camiñas J.A. 2007. Is there a future for artisanal fisheries in the Western Mediterranean? Rome FAO, Copemed, 106 pp.

Kuparinen A., Kuikka S., Merilä J. 2009. Estimating fisheriesinduced selection: traditional gear selectivity research meets fisheries-induced evolution. Evol. Appl. 2: 234-243. PMCid:3352371

Lewejohann L. 2005. Sociogram (Version 1.0). [Computer software].

Lleonart J., Maynou F., Recasens L., Franquesa R. 2003. A bioeconomic model for Mediterranean fisheries, the hake off Catalonia (western Mediterranean) as a case study. Sci. Mar. 67(Suppl.1): 337-351.

Maynou F., Recasens L., Lombarte A. 2011. Fishing tactics dynamics of a Mediterranean small-scale coastal fishery. Aquat. Living Resour. 24: 149-159.

Misund O.A., Kolding J., Fréon P. 2002. Fish capture devices in industrial and artisanal fisheries and their influence on management. In: Hart P.J.B., Reynolds J.D. (eds), Handbook of Fish Biology and Fisheries, vol. II, Blackwell Science, London, pp. 13-36.

Mouillot D., Stubbs W., Faure M., Dumay O., Tomasini J.A. Wilson J.B., Chi T.D. 2005. Niche overlap estimates based on quantitative functional traits: a new family of non-parametric indices. Mar. Biol. 145: 345-353.

Pelletier D., Ferraris J. 2000. A multivariate approach for defining fishing tactics from commercial catch and effort data. Can. J. Fish. Aquat. Sci. 57: 51-65.

Pledger S., Geange S.W. 2009. Niche overlap: A unified definition and analysis for data of different types. Research Report 2009-05 of the School of Mathematics, Statistics and Operations Research. Victoria University of Wellington, New Zealand.

Stergiou K.I., Petrakis G., Politou C.-Y. 1996. Small-scale fisheries in the South Euboikos Gulf (Greece): species composition and gear competition. Fish. Res. 26: 325-336

Suuronen P., Chopin F., Glass C., Løkkeborg S., Matsushita Y., Queirolo D., Rihan D. 2012. Low impact and fuel efficient fishing - looking beyond the horizon. Fish. Res. 119-120: 135-146.

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