30 
Fishery Bulletin 115(1) 
50“N 
30°N 
10° N 
80 W 
60°W 
40°W 
20°W 
Figure 1 
The 11 geographic zones of the U.S. pelagic longline fishery that were analyzed 
for this study to determine the immediate mortality of blue sharks (Priona- 
ce glauca) and tiger sharks {Galeocerdo cuvier) for the period 1992-2008. The 
geographic zones are Caribbean (CAR), Florida east coast (FEC), Gulf of Mex- 
ico (GOM), Mid-Atlantic Bight (MAB), north central Atlantic (NCA), northeast 
coastal (NEC), northeast distant (NED), South Atlantic Bight(SAB), Sargasso 
Sea (SAR), tuna north (TUN), and tuna south (TUS). 
(Cramer and Adams, 2000; Mandelman et al., 2008; 
Fig. 1). These geographic zones were Caribbean (CAR), 
Gulf of Mexico (GOM), Florida east coast (FEC), Mid- 
Atlantic Bight (MAB), north central Atlantic (NCA), 
northeast coastal (NEC), northeast distant (NED), 
South Atlantic Bight (SAB), Sargasso Sea (SAR), tuna 
north (TUN), and tuna south (TUS). Target catch and 
operating procedures for the pelagic longline fleet vary 
among geographic zones, with each described in detail 
in Hoey and Moore^ and in the NMFS consolidated 
flshery management plan for highly migratory species 
(NMFS2). 
Within the USPL, target catch was reported as 
swordflsh, yellowfln tuna (Thunnus albacares), bigeye 
tuna {Thunnus obesus), mixed species of tunas, species 
of sharks, dolphinfish, or other. In accordance with pre- 
vious studies, yellowfln tuna, bigeye tuna, and mixed 
species of tunas were grouped into a single category 
designated as targeting tunas during the mortality 
® Hoey, J. J., and N. Moore. 1999. Captain’s report: multi- 
species catch characteristics for the U.S. Atlantic pelagic 
longline fishery. 78 p. National Fisheries Institute Inc., Ar- 
lington, VA. [Available from website, accessed September 
2015.1 
analysis (Serafy et al., 2012; Gallagher et al., 2014). 
However, a large portion of the data reported targeting 
of multiple species (e.g., swordfish and species of tunas 
in longline sets). Accordingly, for a separate analysis 
of the immediate mortality of target catch, we used a 
reduced data set that excluded longline sets in which 
multiple species were targeted. 
Statistical analysis 
We used generalized linear models with a logit link 
function for each species. This statistical family was 
chosen because the dependent variable was binary, the 
data fitted model assumptions, and Pearson’s residual 
tests confirmed that logistic models fitted the data ap- 
propriately. The response variable {immediate mortality) 
was coded with a value of 0 or 1 according to whether 
an individual shark was discarded alive or dead, respec- 
tively. The final model used for blue sharks was 
Immediate mortality = SST + Regulatory period 
+ Geographic zone + Regulatory period (1) 
X Geographic zone. 
An interaction effect was not examined during the 
