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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 4. December 2011 
FIG. 1. Isla Escondida fishing area indicating location of Escondida Island, Punta Clara, and Punta Tombo. Argentina, 
seabird colonies. 
al. 1998a, Yorio el al. 2005). Kelp Gulls and 
other gulls worldwide can negatively affect other 
coastal birds through predation, competition for 
breeding space and kleptoparasitism. and gener¬ 
ate conflicts with human populations (Yorio et 
al. 1998a, Frere et al. 2000, Albarnaz el al. 
2007). Thus, knowledge of how seabirds use 
fishery waste provided by the Isla Escondida 
coastal fishery will contribute to ecosystein- 
based fisheries management, and provide valu¬ 
able information on the contribution of supple¬ 
mentary lood to an expanding gull population. 
The goal of our study was to analyze the 
interactions between seabirds and coaslal trawl 
vessels targeting Argentine red shrimp (Pleoticus 
muelleri) in the Isla Escondida fishing area with 
emphasis on the Kelp Gull. We identified the 
species composition of seabirds attending vessels 
during two fishing seasons, quantified their 
relative abundance in relation to the fishing 
season and stages of fishing operations, quanti¬ 
sed mortality as a result of incidental capture of 
birds attracted to the vessels to make use of 
fishery waste, and assessed the quantity and 
compos.non of discards potentially available to 
seabim.v 
METHODS 
Study Aren and Characteristics of the Fish¬ 
ery .—The study area comprised the coastal waters 
up to 22.2 km offshore under the jurisdiction of 
Chubut Province from 43" 20' S to 44 02' $ 
(‘Isla Escondida' fishing area) (Fig. 1). The 
coastal trawl fishery operating at Isla Escondida 
targets Argentine red shrimp or Argentine hake 
(Merluccius hubbsi) depending on resource avail¬ 
ability and market demands, but we only evalu¬ 
ated shrimp vessels which were responsible for 
about 80% of the effort of the fishery during the 
study years. The fishery consists of 35-40 coastal 
ice trawlers, 21 m long, which operate from 
November to March. Shrimp vessels remain I or 
2 days in the fishing area, making on average 
seven hauls per day lasting on average 1 hr each 
(Secretaria de Pesca de la Provincia de Chubut. 
unpubl. data). Shrimp are sorted on deck, and non¬ 
commercial sizes and bycatch species are dis¬ 
carded overboard either as a constant stream or in 
pulses depending on the composition of the catch. 
The study area includes three breeding sites 
(Fig. I) of seabirds which regularly interact with 
coastal fisheries in Patagonia: Punta Tombo, Punta 
