148 
Fishery Bulletin 120(2) 
rates may disproportionately affect 1 species and unknow- 
ingly lead to unsustainable harvest rates. 
Conclusions 
In this study, species-specific spatial distributions were 
estimated for bigeye Pacific opah and smalleye Pacific opah 
in US. longline fisheries in the North Pacific Ocean, infor- 
mation that has filled important knowledge gaps. Future 
work incorporating genetic and fisheries data—including 
latitude, longitude, and depth of capture—for samples col- 
lected in a broader spatial range—would help reduce uncer- 
tainty regarding the spatial distributions of and overlap 
between the 2 species. In addition, it would be important to 
determine differences and similarities between the essen- 
tial habitats of each opah species, including foraging ecol- 
ogy, to better quantify the vulnerability of each species to 
different gear configurations. Better understanding of the 
species ranges and associations with different pelagic envi- 
ronments will improve efforts for management of bigeye 
and smalleye Pacific opah. 
Acknowledgments 
We recognize the data managers at the Pacific Islands 
Fisheries Science Center for providing data and insight 
on Hawaii pelagic longline fisheries, the vessel captains 
for providing the logbook data, and the U.S. and Pacific 
Islands Region Observer Programs for the observer data. 
We thank Catalina Offshore Products and the Honolulu 
Fish Auction for providing opah samples for genetic test- 
ing and L. Martin and the rest of the NOAA Southwest 
Fisheries Science Center genetics team for helping with 
collection and analysis of genetic samples. We appreci- 
ate A. Yau, K. Blincow, and E. Portner for valuable guid- 
ance and the 2 anonymous reviewers for their thorough 
feedback. 
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