Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula

The Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey (<i>Petromyzon marinus<...

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Main Authors: Luís Pereira, Ulisses Azeiteiro, Carlos Antunes
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Fishes
Subjects:
Online Access:https://www.mdpi.com/2410-3888/10/5/230
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author Luís Pereira
Ulisses Azeiteiro
Carlos Antunes
author_facet Luís Pereira
Ulisses Azeiteiro
Carlos Antunes
author_sort Luís Pereira
collection DOAJ
description The Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey (<i>Petromyzon marinus</i>), shads (<i>Alosa alosa</i> and <i>Alosa fallax</i>), trout (<i>Salmo trutta</i>), and European eel (<i>Anguilla anguilla</i>), during their reproductive migration and riverine periods. A total of 3242 individuals from 15 species were sampled, with native species accounting for 51.1% of the catch. Results revealed significant differences in size and weight of lampreys, with individuals from the Lima River being significantly smaller than those from regional rivers such as the Minho and Mondego. Shad populations showed a high proportion of hybrids (33.8%), suggesting extensive hybridization between <i>A. alosa</i> and <i>A. fallax</i>. Analysis of trout stomach contents revealed a diverse diet dominated by insects (66.9%), crustaceans (6.8%), and fish (6.8%), but also an alarming presence of plastic debris (1.1%), highlighting potential pollution problems. For European eels, this study marks the first record of the invasive swim bladder parasite <i>Anguillicola crassus</i> in the Lima River, with 84.8% of eels sampled showing moderate to severe swim bladder damage. These findings contribute to a deeper understanding of diadromous fish ecology and emphasize the importance of conservation efforts in estuarine systems worldwide.
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spelling doaj-art-21bf3e5ed80a48dba55ae420b2b1f83e2025-08-20T03:14:41ZengMDPI AGFishes2410-38882025-05-0110523010.3390/fishes10050230Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian PeninsulaLuís Pereira0Ulisses Azeiteiro1Carlos Antunes2CESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, 3810-193 Aveiro, PortugalCESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, 3810-193 Aveiro, PortugalInterdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, PortugalThe Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey (<i>Petromyzon marinus</i>), shads (<i>Alosa alosa</i> and <i>Alosa fallax</i>), trout (<i>Salmo trutta</i>), and European eel (<i>Anguilla anguilla</i>), during their reproductive migration and riverine periods. A total of 3242 individuals from 15 species were sampled, with native species accounting for 51.1% of the catch. Results revealed significant differences in size and weight of lampreys, with individuals from the Lima River being significantly smaller than those from regional rivers such as the Minho and Mondego. Shad populations showed a high proportion of hybrids (33.8%), suggesting extensive hybridization between <i>A. alosa</i> and <i>A. fallax</i>. Analysis of trout stomach contents revealed a diverse diet dominated by insects (66.9%), crustaceans (6.8%), and fish (6.8%), but also an alarming presence of plastic debris (1.1%), highlighting potential pollution problems. For European eels, this study marks the first record of the invasive swim bladder parasite <i>Anguillicola crassus</i> in the Lima River, with 84.8% of eels sampled showing moderate to severe swim bladder damage. These findings contribute to a deeper understanding of diadromous fish ecology and emphasize the importance of conservation efforts in estuarine systems worldwide.https://www.mdpi.com/2410-3888/10/5/230anadromous speciescatadromous speciesLima River<i>Anguillicola crassus</i>fish migrationfisheries management
spellingShingle Luís Pereira
Ulisses Azeiteiro
Carlos Antunes
Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
Fishes
anadromous species
catadromous species
Lima River
<i>Anguillicola crassus</i>
fish migration
fisheries management
title Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
title_full Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
title_fullStr Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
title_full_unstemmed Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
title_short Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula
title_sort assessing diadromous fish populations in the lima river northwest iberian peninsula
topic anadromous species
catadromous species
Lima River
<i>Anguillicola crassus</i>
fish migration
fisheries management
url https://www.mdpi.com/2410-3888/10/5/230
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AT ulissesazeiteiro assessingdiadromousfishpopulationsinthelimarivernorthwestiberianpeninsula
AT carlosantunes assessingdiadromousfishpopulationsinthelimarivernorthwestiberianpeninsula