Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)

Some relict populations of the native crayfish Austropotamobius pallipes have been located in rivers in Bizkaia, (Basque Country, Spain), and its population numbers and dynamics, and habitat conditions have been studied for three years. The first descriptive results are given in this paper....

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Main Authors: GARCÍA-ARBERAS L., RALLO A.
Format: Article
Language:English
Published: EDP Sciences 2000-01-01
Series:Knowledge and Management of Aquatic Ecosystems
Subjects:
Online Access:http://dx.doi.org/10.1051/kmae:2000002
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spelling doaj-240b8740e18c4bdb95e91bdd5d8500b12020-11-24T22:48:08ZengEDP SciencesKnowledge and Management of Aquatic Ecosystems1961-95022000-01-010356173010.1051/kmae:2000002kmae200035602Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)GARCÍA-ARBERAS L.RALLO A. Some relict populations of the native crayfish Austropotamobius pallipes have been located in rivers in Bizkaia, (Basque Country, Spain), and its population numbers and dynamics, and habitat conditions have been studied for three years. The first descriptive results are given in this paper. The native crayfish populations must be considered residual because of the disrupted area distribution and highly fluctuating demography of the species. Up to now, the species has been located in more than thirty fluvial areas of relatively high slope and shallow and good quality water. Population characteristics (sex ratio, length and weight relations and length frequency classes) are studied in nineteen cases. Maximal relative population numbers are about 100 captures per hour ; these values are correlated to variables of conductivity, hardness, and concentrations of nitrates, nitrites, magnesium, potassium and ammonium. The degree of mineralization must reach a minimum level and, within the values found in the studied rivers, its increase favours the population of crayfish. Management measures to conserve native crayfish must include the protection and improvement of their habitat, prevention of access to it and to the commencement of a genetic study to palliate the phenomenon of endemism. It would also be highly recommendable to begin experimental restocking of riverbeds now without crayfish fauna and with apparently optimum conditions for the establishment of populations of autochthonous crayfish. http://dx.doi.org/10.1051/kmae:2000002crayfishnative speciespopulationriversecologySpain
collection DOAJ
language English
format Article
sources DOAJ
author GARCÍA-ARBERAS L.
RALLO A.
spellingShingle GARCÍA-ARBERAS L.
RALLO A.
Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
Knowledge and Management of Aquatic Ecosystems
crayfish
native species
population
rivers
ecology
Spain
author_facet GARCÍA-ARBERAS L.
RALLO A.
author_sort GARCÍA-ARBERAS L.
title Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
title_short Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
title_full Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
title_fullStr Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
title_full_unstemmed Survival of natural populations of Austropotamobius pallipes in rivers in Bizkaia, Basque Country (North of Iberian Peninsula)
title_sort survival of natural populations of austropotamobius pallipes in rivers in bizkaia, basque country (north of iberian peninsula)
publisher EDP Sciences
series Knowledge and Management of Aquatic Ecosystems
issn 1961-9502
publishDate 2000-01-01
description Some relict populations of the native crayfish Austropotamobius pallipes have been located in rivers in Bizkaia, (Basque Country, Spain), and its population numbers and dynamics, and habitat conditions have been studied for three years. The first descriptive results are given in this paper. The native crayfish populations must be considered residual because of the disrupted area distribution and highly fluctuating demography of the species. Up to now, the species has been located in more than thirty fluvial areas of relatively high slope and shallow and good quality water. Population characteristics (sex ratio, length and weight relations and length frequency classes) are studied in nineteen cases. Maximal relative population numbers are about 100 captures per hour ; these values are correlated to variables of conductivity, hardness, and concentrations of nitrates, nitrites, magnesium, potassium and ammonium. The degree of mineralization must reach a minimum level and, within the values found in the studied rivers, its increase favours the population of crayfish. Management measures to conserve native crayfish must include the protection and improvement of their habitat, prevention of access to it and to the commencement of a genetic study to palliate the phenomenon of endemism. It would also be highly recommendable to begin experimental restocking of riverbeds now without crayfish fauna and with apparently optimum conditions for the establishment of populations of autochthonous crayfish.
topic crayfish
native species
population
rivers
ecology
Spain
url http://dx.doi.org/10.1051/kmae:2000002
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