Avifauna associated with an otter-trawl fishery in a tropical estuary

Otter trawls are commonly used in fisheries for benthic fishes, and they provide a source of food to many marine birds. This study aimed to quantify the response of birds, by species, attracted to forage at fishing vessels in Ribeira Bay, Angra dos Reis, Rio de Janeiro, Brazil. Sampling was conducte...

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Bibliographic Details
Published inMarine ornithology Vol. 48; no. 2; p. 283
Main Authors Freret-Meurer, Natalie Villar, Andreata, José Vanderli, Alves, Maria Alice S
Format Journal Article
LanguageEnglish
Published Honolulu Pacific Seabird Group 01.10.2020
Subjects
Aquatic birds
Ardea alba
Avifauna
Benthos
Benthos collecting devices
Birds
Boats
Estuaries
Estuarine dynamics
Fish
Fisheries
Fishing
Fishing vessels
Foraging
Fregata magnificens
Mammals
Phalacrocorax brasilianus
Seabirds
Sterna hirundinacea
Trawling
Trawlnets
Tropical climate
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Summary:Otter trawls are commonly used in fisheries for benthic fishes, and they provide a source of food to many marine birds. This study aimed to quantify the response of birds, by species, attracted to forage at fishing vessels in Ribeira Bay, Angra dos Reis, Rio de Janeiro, Brazil. Sampling was conducted every two months in 2006 at five stations, for a total of 30 trawls; fish were collected for 20 minutes per trawl. Bird counts were recorded just before the trawling started, when it began, 10 minutes after trawling began, and 10 minutes after it stopped. After trawling, 10 fresh dead fish were released into the water, and we recorded the number of successful and unsuccessful attacks. Our 224 observations included eight bird species; three species-Magnificent Frigatebird Fregata magnificens, Neotropic Cormorant Phalacrocorax brasilianus, and Great Egret Ardea alba-accounted for 68.3%, 10.7%, and 5.8% of the records, respectively. Scoring highest in a Frequency of Occurrence Index were the Magnificant Frigatebird, South American Tern Sterna hirundinacea, and Brown Booby Sula leucogaster, with 75%, 30%, and 25%, respectively. When trawling started, 21% of the eventually recorded birds approached the boat, but after 10 minutes, they dispersed. After trawling stopped, 77% of the eventually recorded birds approached. Most attacks on discarded fish were performed by frigatebirds (79%), which were also the most efficient in getting fish (83%). Our results emphasize the important association of frigatebirds with trawling, in accord with its kleptoparasitic mode of foraging.
ISSN:1018-3337
2074-1235