Effect of illegal glass eel (Anguilla anguilla) fishery on estuarine fish stocks: a case study in the Mondego Estuary, Portugal
João Bernardo Neves
A B C D , Filipe Martinho A and Miguel Ângelo Pardal A
+ Author Affiliations
- Author Affiliations
A Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, PT-3000-456 Coimbra, Portugal.
B Marine and Environmental Sciences Centre, University of the Azores, Rua Prof. Dr Frederico Machado, 4, PT-9900-138 Horta, Açores, Portugal.
C Present address: Okeanos – R&D Centre, University of the Azores, Rua Prof. Dr Frederico Machado, 4, PT-9900-138 Horta, Açores, Portugal.
D Corresponding author. Email: jfbneves@gmail.pt
Marine and Freshwater Research 69(11) 1692-1703 https://doi.org/10.1071/MF17364
Submitted: 30 November 2017 Accepted: 13 April 2018 Published: 23 July 2018
Abstract
Illegal fishing is a critical activity that affects a wide range of species, leading to a decline in total abundance and the overexploitation of target and non-target species. In Portugal, despite fishing for eel juveniles not being allowed, a substantial amount of illegal fishing takes place during the migratory season (October–March). The aim of this study was to investigate the effects of glass eel fishing in the Mondego estuary on target and non-target species. Samples were collected between November 2011 and March 2013 during the autumn and winter (dry and regular respectively with regard to hydrological characteristics) in 2 years. No differences in glass eel catches were observed between fishing seasons; however, a higher number of non-target species was observed in 2012–13 (regular year). There was higher species diversity in the regular year, as well as the highest number of individuals. Higher catches of the most abundant species were also observed in the regular year, compared with the dry year, suggesting that the magnitude of the effect of these illegal practices is related to hydrological cycles. Despite the low replication (2 years), the present study shows that non-selective practices have considerable effects on the species captured, as well as on the functioning of the estuarine ecosystem.
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