Are the fisheries in the Tagus estuary sustainable?

Abstract

The comparative sustainability of seven Tagus estuary fisheries – beam trawl, boat dredge, nets for glass eel, gill nets, eel basket, squid jig and octopus traps – is analysed using RAPFISH. This technique relies upon ordination of scored attributes, grouped in fields that cover ecological, economic, social, technological and ethical sustainability, performed using multi-dimensional scaling. Fisheries were analysed within each discipline and using all the attributes for an interdisciplinary approach. Leverage analysis is used to determine how much each attribute influences the ordination. Concerning the cross-discipline ordination, the studied fisheries lay around the mid-range of sustainability. The most sustainable fishery is octopus traps (57%) followed by squid jig (56%) that has the same results except for technological dimension. Eel basket and gill nets show the next best sustainability scores (55% and 53%, respectively). Glass eel fishery presents a poor sustainability (46%), lying close to the boat dredge and beam trawl, the fisheries with lowest sustainability (44% and 43%, respectively). The low leverage values show that ordinations are truly multivariate and that the results are not dominated by any one attribute. More studies should be conducted on the Tagus estuary fisheries in order to get more information about resources, fishers and their activity, which will contribute to improve sustainability.