Marinao and Yorio • SEABIRD MORTALITY AND FISHERY DISCARDS 
713 
1200 
600 
0 
240 
160 
•3 
Kelp Gull 
(A) 
(B) 
b 
JO 
2 
n,-n,n, a n,U,-M,.an,n 
Black-browed Albatross 
n fl fin fin fl n(lr,n n n 
n II n II n II n II n n II 
n. 1 -IIiIBb.J 
m n ■ . 
n 
White-chinned Petrel 
. „ fl I ijj 
Dll „ll. 
nUflDnflfln ™ n n 
Imperial Shag 
nn n nn n ^ 
n 
Li 
L.i.i 
1 3 5 7 9 11 13 15 17 19 1 3 5 7 9 11 13 15 17 19 
Number of hauls 
FIG. 2. Numbers of the four most frequent and abundant seabird species attending coastal shrimp trawlers in the Isla 
Escondida area, Argentina, during the (A) 2006-2007 and (B) 2007-2008 fishing seasons. 
browed Albatross: 64.8 ± 73.8 vs. 18.4 ± 22.0, 
Mann-Whitney U = 88, P = 0.01). 
Incidental Seabird Mortality .—Fifteen individ¬ 
uals were caught in 3.149 hauls evaluated by the 
On-board Observer Program, of which three were 
able to escape alive. The 12 birds killed included 
11 Magellanic Penguins and one Imperial Shag, 
resulting in a mean mortality rate of 0.003 and 
0.0003 birds per haul, respectively. Extrapolating 
this value to the total number of hauls by the Isla 
Escondida fishery in the 2 years (n = 15,232 
hauls), we estimated a total of 53 penguins and 5 
shags were killed in nets. These estimates are an 
indication of the actual numbers of birds killed. 
No contacts (fatal and non-fatal) between seabirds 
and warp cables were recorded (n - 40 hauls). 
Spatial Distribution of the Fishery and Discard 
Composition.— Hauls were distributed between 
43 30' and 44" 10' S during both study years with 
most occurring between 43 65' and 43 75' S 
TABLE 2. Mean ± SD (range in parentheses) of individuals per haul during two different stages of the fishing 
operation (n - 20). for the four most frequent and abundant seabird species attending vessels in the Isla Escondida area, 
Argentina, during the 2007-2008 fishing season. 
Species Haulback Discarding Wilcoxon tesl 
Kelp Gull 131.5 ± 204.9 (0-750) 263.4 ± 384.3 (32-1,700) 
Black-browed Albatross 21.5 ± 33.3 (0-120) 32.4 ± 47.3 (0-210) 
Imperial Shag 18.8 ± 42.2 (0-160) 17.8 ± 29.5(0-100) 
White-chinned Petrel 7.1 ± 10.2 (0-35) 9.85 ± 11.7 (0-55) 
P < 0.0001 
P < 0.0001 
P = 0.99 
P = 0.10 
