Dapp et ai.: Immediate mortality of Prionoce glauca and Galeocerdo cuvier caught by pelagic longlines 
39 
line fishery. Additionally, fin-to-carcass ratios have not 
increased retention rates for tiger sharks (the mean 
percentages retained were 16% in 1992-1993 and 14% 
in 1993-2008) because these sharks are large-bodied 
animals, boats often have limited deck space, and their 
meat has a low commercial value (Mandelman et ah, 
2008; Simpfendorfer, 2009). Similarly, regulations that 
require the use of circle hooks during commercial long- 
line operations have decreased the rate of immediate 
mortality for blue shark by 8.0%. Our study adds sup- 
port to the assumption that fisheries regulations have 
been beneficial to some species, and results from recent 
studies indicate that species of sharks caught in the 
U.S. longline fishery are stable or increasing in abun- 
dance (Carlson et ah, 2012). 
Acknowledgments 
Financial support to conduct this work was provided 
by the Australian Research Council Linkage Project 
LPl 10200572, the Holsworth Wildlife Research En- 
dowment, Fisheries Victoria, the Australian Fisher- 
ies Management Authority, Melbourne Aquarium, and 
Monash University. We thank 3 anonymous reviewers 
for providing feedback on previous iterations of our 
manuscript. 
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