Cooper et al.: Spatiotemporal catch patterns and population distributions of Lampris megalopsis and L. incognitus 141 
changing the beginning of the fisheries data time series 
to 1996. The use of these criteria resulted in a final data 
set of 330,599 deep-set gear sets and 43,326 shallow-set 
gear sets spanning from 1996 through 2018, with 89% and 
54% of data remaining from the original unfiltered data 
sets, respectively. Almost 40% of the shallow-set data were 
filtered out simply because of missing critical fields in the 
data set (hooks per float, hooks per set, soak time, or geo- 
graphic coordinates). 
The areas fished by both fleets have changed since the 
beginning of the longline fisheries. During the 1990s, the 
deep-set fishery was primarily confined to the waters 
around the main Hawaiian Islands, but effort began 
to expand eastward in the 2000s (Woodworth-Jefcoats 
et al., 2018). This expansion accelerated after 2013. From 
1996 through 2013, only 9% of the longline sets in the 
deep-set fishery occurred in waters east of 150°W, and 
that percentage increased to 26% during 2014-2018. 
1996-2013 _ 
No. of hooks set 
200,000 
150,000 
~ 100,000 
50,000 
0 
N | 
7 1000'-2000km CN) 
QO 1000 2000km | 
-120°W 
140°W 
CPUE 
2.0 
1.5 
1.0 
— 0.5 
0.0 
N 
_—= | | 
0 1000 2000km ® 
The percentage of sets in the shallow-set fishery that 
occurred east of 150°W increased from 25% to 53% over 
those same time frames. 
Consequently, 2 periods were considered for analyses: 
1996-2013 and 2014-2018. Filtered logbook data were 
binned into 5°-by-5° blocks to visualize effort (number of 
hooks set) and CPUE (number of individual opah landed 
per 1000 hooks). For confidentiality purposes, visualiza- 
tions of effort and CPUE do not display blocks containing 
less than 3 unique vessels within each figure’s specified 
period, although the data were still included in the overall 
calculations and analyses of fishery trends. Blocks contain- 
ing less than 20 total sets of deep-set longlines or less than 
10 total sets of shallow-set longlines were also removed 
from their respective analyses to ensure sufficient sample 
sizes. The shallow-set fishery had overall lower amounts of 
data and effort; therefore, a lower threshold was estab- 
lished to maximize spatial data. 
2014-2018 
N 
— a | 
01000 2000km (A) 
~140W Ss 120°W 
N 
1000 2000km ® 
0°, : 0 
160°W 140°W 120°W 
180° —160W ti«‘iW SS S«1 20° 
Figure 2 
Map of the (A and B) average annual effort, measured as number of hooks, and (C and D) aggregate nominal catch per unit 
of effort (CPUE), measured as number of individuals per 1000 hooks, for opah (Lampris spp.) caught by the U.S. shallow-set 
longline fishery during 1996-2013 and 2014—2018 in the central and eastern North Pacific Ocean. Logbook data are binned into 
5°-by-5° blocks, and blocks with data from less than 3 vessels are not shown to maintain confidentiality. 
