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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123. No. 4. December 2011 
FIG. 3. Spaiial distribution of hauls by coastal shrimp 
and February 2006-2007 and 2007-2008. 
trawlers in the 
Isla Escondida area, Argentina, during January 
(Fig. 3). Hauls were generally between 15 and 
20 km offshore, although in January 2007 some 
hauls were <5 km from the coast (Fig. 3). Coastal 
shnmp vessels operated at a mean distance from 
Puma Tombo of 43.9 ± 10.0 km (range = 7.1- 
73.3; n - 1.219), while mean distance to Punta 
Clara was 38.0 ± 9.5 km (range = 1.5-67.5; n = 
1,219). Mean distance between operating vessels 
and the Imperial Shag colony at Escondida 
Island was 20.4 ± 6.5 km (range = 2.8-46.6; n = 
1,219). Distances to these colonies decreased 
significantly as the breeding season progressed 
(Table 3). 
At least 100 species were discarded in the 1 21 1 
evaluated hauls, of which 48% were fish (Table 4 
only species with ^20% of frequency of occur 
rence are shown). Argentine hake was recorded h 
l 6 ‘J ot hauls. Hake was totally retained in onb 
-/ f of hauls ’ wh »lc >« was discarded (74.3%) o' 
partially retained (25.0%) in the rest of the hauls 
Several of the remaining discarded species were 
Present in the catch in relatively high frequencies 
but were categorized as rare in over 83% of hauls 
(Table 4). Thus, the Argentine hake was the main 
species discarded. The estimated amount of 
discards per haul was significantly higher in the 
2007-2008 than in the 2006-2007 fishing seasons 
(513.46 ± 576.43 kg; range = 0-8,000; n = 
1,152 vs. 305.05 ± 382.86 kg; range = 0-2.490: 
n = 469) (Mann-Whitney U = 285,847.50 P < 
0.0001). Total amount discarded by this coastal 
trawl fishery was estimated at 3.284 tonnes in 
2006-2007 and 6,590 tonnes in 2007-2008. 
DISCUSSION 
Eight seabird species attended shrimp coastal 
trawlers operating in the Isla Escondida fishing 
area, although the seabird assemblage was 
dominated by the Kelp Gull and Black-browed 
albatross. Species composition differed from that 
reported in a previous study in the same fishing 
area during the mid 1990s. when 16 seabird 
species were recorded taking advantage of 
discards (Yorio and Caille 1999k The reason for 
this difference is not clear, but five ofthe species 
not recorded during the present study (Cape Petrel 
