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Auteur Ba, K.; Thiaw, M.; Lazar, N.; Sarr, A.; Brochier, T.; Ndiaye, I.; Faye, A.; Sadio, O.; Panfili, J.; Thiaw, O.T.; Brehmer, P.
Titre Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change Type Article scientifique
Année 2016 Publication Revue Abrégée PLoS One
Volume 11 Numéro 6 Pages e0156143
Mots-Clés age; aurita; eba val; growth; length; maderensis lowe; maturity; pointe-noire region; recruitment; west-africa
Résumé The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed significantly. The above parameters of S. maderensis have hardly changed, despite high exploitation and fluctuations in environmental conditions that affect the early development phases of small pelagic fish in West Africa. This lack of plasticity of the species regarding of the biological parameters studied should be considered when planning relevant fishery management plans.
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ISSN 1932-6203 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1630
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Auteur Ndiaye, W.; Thiaw, M.; Diouf, K.; Ndiaye, P.; Thiaw, O.T.; Panfili, J.
Titre Changes in population structure of the white grouper Epinephelus aeneus as a result of long-term overexploitation in Senegalese waters Type Article scientifique
Année 2013 Publication Revue Abrégée African Journal of Marine Science
Volume 35 Numéro 4 Pages 465-472
Mots-Clés West Africa; africa; biological indicators; communities; diversity; evaluate; fishing pressure; hermaphroditism; indicators; length at maturity; management; reef fishes; serranidae; size; size spectra; spectrum
Résumé In Senegal, a significant decrease in catches indicates that many demersal fish stocks are being overexploited. The white grouper Epinephelus aeneus, locally known as the 'thiof', is exploited by both small-scale and industrial fisheries. A 28-year database of E. aeneus catches along the Senegalese coast provided by the Centre for Oceanographic Research of Dakar-Thiaroye, and size at maturity measured in Dakar (Senegal) from monthly samples in 2010, were used to analyse changes in population structure in the area over the past 37 years. Catches from the northern fishing areas were lower than those from the southern fishing areas, and decreased steadily during the period (Kolmogorov-Smirnov test, D = 0.243, p = 0.0002). The individual mean weight of catches decreased from 1974 to 2010 (linear regression, r(2) = 0.40, n = 37) and only 60% of the individuals were mature. The calculated sizes at maturity were 49 cm total length (TL) for females and 55 cm for males, and the optimal length of capture for a sustainable fishery was 96 cm, but only 0.03% of E. aeneus caught reached this length. Most of the catch consisted of juveniles; the larger reproductive individuals had disappeared. The number of individuals caught decreased significantly between 1974 and 2010 (1974-1983, r(2) = 0.98, n = 74 674; 1984-1993, r(2) = 0.95, n = 96 696; 1994-2003, r(2) = 0.93, n = 12 619; 2004-2010, r(2) = 0.91, n = 12 887), whereas the length range remained the same (10-110 cm TL). Biological indicators clearly showed that E. aeneus stocks in Senegal are overexploited and the species is now endangered. Immediate active management of fishing pressure is needed, therefore, to maintain E. aeneus populations in the area. Our results suggest a minimum size of <50 cm should be introduced and that fishing effort should be reduced.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1814-232x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 484
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