First morphological, biological and genetic characteristics of shads (Alosa alosa and Alosa fallax spp) in the River Charente (France).

• Tipo: Artigo em Revista Científica Internacional
• Data: 2001

Autores

veron, v (Autor) Outra; sabatie, r (Autor) Outra; bagliniere, jl (Autor) Outra; alexandrino, p (Autor) FCUP

Revista

Título: BFPP - Bulletin Francais de la Peche et de la Protection des Milieux Aquatiques

Vol. 71

Páginas: 1037-1057

ISSN: 0767-2861

Editora: CONSEIL SUPERIEUR DE LA PECHE

Indexação

ISI Web of Knowledge - 5 Citações

Classificação Científica

FOS: Ciências agrárias > Agricultura, silvicultura e pescas

Outras Informações

ID Authenticus: P-008-KNW

DOI: 10.1051/kmae:2001035

Abstract (EN): Two species of Atlantic shads (Alosa alosa and Alosa fallax) colonize Charente but their populations have never been described contrary to those of the largest French rivers. The physical properties of the basin are presented : quality of water, habitats and obstacles to the migration. The allis shad colonize Charente till Angouleme (171 km) when the hydraulic conditions of May and April erase the 21 dams located downstream. Active spawning areas were located. Twaite shads are blocked downstream by the dam Crouin (102 km Cognac downstream) and only one active spawning area was located. The abundance of these two stocks of shads cannot be estimated because the only data available are captures made by the commercial fishing and angling. The morphological and genetic characterization of the two species was made by counting meristic, morphometric measurements and taking away (scale, muscle tissue and blood) carried out in 1997 and 1998. The average total number of branchiospines of the first left branchial arch for the allis shad is 125 against 42 for the twaite shads. The relation between length and weight was calculated for each species and according to the date of capture. Whatever the species, the females have an average size higher than males. The females of allis shad are old on average 5 years and males 4 years old, none sampled fish presented marks of previous reproduction. The females and the males of twaite shads are old on average 3 years, 12.5 % of the females already reproduced once and 3.5 % twice. In the males, 40 % already reproduced once. The temporal range of reproduction was determined by follow-up of ground and investigations. That of the allis shad is located between the first fortnight of May and the first fortnight of June. That of the twaite shads during the second fortnight of May and the first fortnight of June. The comparison of their characteristics with the one of shads coming from stocks already studied indicates that they are closed to the populations of shads coming from the Loire river. The genetic characterization of two stocks was carried out by electrophoresis of the proteins (8 loci). That of allis shad of Charente presents some allelic frequencies distributions relatively close to those of the populations characterized before but is characterized by lower rates of heterozygoty and by a greater number of heterozygous loci. All in all, the twaite shads of Charente appear much less polymorph than those of the whole of the studied Atlantic populations. The comparison of the French, Portuguese and Moroccan populations by the analysis of the genetic distances confirms the character far from polymorph of the populations of allis shad compared to those of twaite shad.

Idioma: Francês

Tipo (Avaliação Docente): Científica

Nº de páginas: 21