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Titre du document / Document title

Abundance of irrawaddy dolphins (Orcaella brevirostris) and ganges river dolphins (Platanista Gangetica gangetica) estimated using concurrent counts made by independent teams in waterways of the sundarbans mangrove forest in Bangladesh

Auteur(s) / Author(s)

SMITH Brian D. (1) ; BRAULIK Gill (2) ; STRINDBERG Samantha (1) ; AHMED Benazir (3) ; MANSUR Rubaiyat (4) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York 10460, ETATS-UNIS
(2) Downstream Research Group, 3950 S. Fletcher Avenue, Fernandina Beach, Florida 32034, ETATS-UNIS
(3) Department of Zoology, Chittagong University, Chittagong, BANGLADESH
(4) The Guide Tours Ltd. Darpan Complex, Plot-2, Gulshan 2, Dhaka, BANGLADESH

Résumé / Abstract

Independent observer teams made concurrent counts of Irrawaddy dolphins Orcaella brevirostris and Ganges River dolphins Platanista gangetica gangetica in mangrove channels of the Sundarbans Delta in Bangladesh. These counts were corrected for missed groups using mark-recapture models. For Irrawaddy dolphins, a stratified Lincoln-Petersen model, which incorporated group size and sighting conditions as covariates, and a Huggins conditional likelihood model, which averaged models that individually incorporated group size, sighting conditions, and channel width as covariates, generated abundance estimates of 397 individuals (CV = 10.2%) and 451 individuals (CV = 9.6%), respectively. For Ganges River dolphins, a stratified Lincoln-Petersen model, which incorporated group size as a covariate, and a Huggins conditional likelihood model, which averaged the same models described above, generated abundance estimates of 196 individuals (CV = 12.7%) and 225 individuals (CV = 12.6%), respectively. Although the estimates for both models were relatively close, the analytical advantages of the Huggins models probably outweigh those of the Lincoln-Petersen models. However, the latter should be considered appropriate when simplicity is a priority. This study found that waterways of the Sundarbans support significant numbers of Irrawaddy and Ganges River dolphins, especially compared to other areas where the species have been surveyed.

Revue / Journal Title

Marine mammal science    ISSN  0824-0469   CODEN MMSCEC 

Source / Source

2006, vol. 22, no3, pp. 527-547 [21 page(s) (article)] (2 p.3/4)

Langue / Language

Anglais

Editeur / Publisher

Wiley, Hoboken, NJ, ETATS-UNIS  (1985) (Revue)

Mots-clés anglais / English Keywords

Cetacea

;

Aquatic environment

;

Vertebrata

;

Asia

;

Bangladesh

;

Ganges River

;

Brackish water environment

;

Freshwater environment

;

Mammalia

;

Marine environment

;

Models

;

Capture recapture method

;

Bangladesh

;

Forests

;

Mangrove

;

Mots-clés français / French Keywords

Cetacea

;

Milieu aquatique

;

Vertebrata

;

Asie

;

Bangladesh

;

Rivière Gange

;

Delphinidae

;

Milieu saumâtre

;

Milieu eau douce

;

Mammalia

;

Milieu marin

;

Modèle

;

Méthode capture recapture

;

Bengla Desh

;

Forêt

;

Mangrove

;

Mots-clés espagnols / Spanish Keywords

Cetacea

;

Medio acuático

;

Vertebrata

;

Asia

;

Río Ganges

;

Medio salobre

;

Medio agua dulce

;

Mammalia

;

Medio marino

;

Modelo

;

Método marca sobremarca

;

Bangla Desh

;

Bosque

;

Manglar

;

Mots-clés d'auteur / Author Keywords

Irrawaddy dolphins

;

Orcaella brevirostris

;

Ganges River dolphins

;

Platanista gangetica

;

abundance estimation

;

Chapman's modified Lincoln-Petersen mark-recapture estimator

;

Huggins conditional likelihood model

;

correction factors

;

independent concurrent counts

;

Sundarbans

;

mangroves

;

Bangladesh

;

Localisation / Location

INIST-CNRS, Cote INIST : 21403, 35400014243290.0020

Nº notice refdoc (ud4) : 17896937



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