Barlow and Berkson Evaluating methods for estimating rare events with zero heavy data 
349 
Table 2 
The number of computational groups of 25 fishing sets and bycatch probabilities per stratum that were included in the simulation 
model built to represent interactions of sea turtles with the U.S. Atlantic pelagic longline fishery. Bycatch probabilities differed 
between scenarios with clumping turtles and scenarios with turtles placed with a uniform probability because of the different 
turtle densities. Clumping means that turtles tend to concentrate in certain areas rather than occur equally spaced or spaced 
with uniform probability. The SEFSC estimates bycatch of sea turtles for each of 4 calendar quarters (Q1 through Q4) and for 
each of 10 geographic regions or fishing areas. The SEFSC uses the following names for these fishing areas: CAR=Caribbean, 
FEC = Florida East Coast, GOM = Gulf of Mexico, MAB = Mid-Atlantic Bight, NCA=North Central Atlantic, NEC=Northeast 
Coastal, NED=Northeast Distant, SAB = South Atlantic Bight, SAR=Sargasso Sea, and TUN=Tuna North. We simulated 32 
quarter-area strata because 8 strata were without fishing or observer coverage from 2005 to 2007. 
Simulated 
quarter-area 
stratum 
SEFSC 
quarter-area 
stratum basis 
Number of 
computational groups 
simulated 
Bycatch probability: 
turtles 
uniformly random 
Bycatch probability: 
turtles 
clumping 
1 
Ql-CAR 
3 
6. 17xl0- 3 
2.50xl0“ 4 
2 
Ql-FEC 
8 
1.15xl0- 2 
4.65xl0- 4 
3 
Ql-GOM 
39 
2.36xl0- 3 
9.55xl0- 5 
4 
Ql-MAB 
6 
5.20xl0- 3 
2.11xl0 -4 
5 
Ql-NCA 
1 
2.74x10-3 
l.llxlO- 4 
6 
Ql-SAB 
5 
8.98x10-3 
3.64xl0 -4 
7 
Ql-SAR 
4 
O 
X 
© 
CO 
1.25xl0- 4 
8 
Ql-TUN 
1 
2.74x10-3 
l.llxlO- 4 
9 
Q2-CAR 
1 
6.17x10-3 
2.50xl0- 4 
10 
Q2-FEC 
7 
2.74x10-3 
l.llxlO- 4 
11 
Q2-GOM 
40 
5.57x10-3 
2.25xl0- 4 
12 
Q2-MAB 
10 
5.20x10-3 
2.11xl0 -4 
13 
Q2-NCA 
1 
2.74x10-3 
l.llxlO- 4 
14 
Q2-NEC 
2 
1.32xl0- 2 
5.33xl0- 4 
15 
Q2-NED 
1 
2.59xl0- 2 
1.05x10-3 
16 
Q2-SAB 
19 
8.98xl0- 3 
3.64x10"“ 
17 
Q2-TUN 
2 
2.74x10-3 
l.llxlO- 4 
18 
Q3-FEC 
6 
7.11xl0- 3 
2.88xl0- 4 
19 
Q3-GOM 
38 
1.07x10-3 
4.35xl0- 5 
20 
Q3-MAB 
24 
3.14xl0- 3 
1.27xl0- 4 
21 
Q3-NEC 
12 
1.99xl0- 2 
QO 
b 
00 
X 
o 
22 
Q3-NED 
12 
2.23x10-2 
9.02x10-“ 
23 
Q3-SAB 
5 
8.98x10-3 
3.64x10-“ 
24 
Q3-TUN 
2 
2.74x10-3 
1.11x10-“ 
25 
Q4-FEC 
3 
7.11xl0- 3 
2.88x10-“ 
26 
Q4-GOM 
31 
1.02x10-2 
4.14x10-“ 
27 
Q4-MAB 
23 
7.26x10-3 
2.94x10-“ 
28 
Q4-NCA 
2 
6.17x10-3 
2.50x10-“ 
29 
Q4-NEC 
3 
2.96x10-2 
1.20x10-3 
30 
Q4-NED 
5 
8.98x10-3 
3.64x10-“ 
31 
Q4-SAB 
2 
2.35x10-2 
9.52x10-“ 
32 
Q4-SAR 
2 
2.74x10-3 
1.11x10-“ 
to 2007 and rounded to multiples of 25 to determine the 
number of computational groups of 25 sets that would 
be modeled per stratum. 
Each computational group of 25 sets was modeled as a 
grid of 100x100 cells. Sea turtles and fishing sets were 
assigned coordinates (jc, y) depending on the spatial 
scenario. The details of the procedures are described 
in the following sections. Modeled sets covered 5 cells — 
an initial cell and 4 cells either up, right, down, or 
left — because the average longline set covers about 50 
km (mean 47 km, minimum 32 km, maximum 64 km) 
(Witzell, 1999; Beerkircher et al., 2004; Gilman et ah, 
2006). Hence, modeled cells were conceptualized as 
10x10 km. 
