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Fishery Bulletin 108(3) 
<V 
Elapsed time after setting long lines 
Figure 5 
Hook-timer data for 10 species caught on longlines (n=284) in the domestic 
Reunion Island fishery between June 1998 and November 2000. Height of 
each bar represents the sum of frequencies for (A) the main commercial 
species and for (B) billfish and other bycatch species. 
of the trajectories on a finer scale would help in elu- 
cidating the foraging behavior in three dimensions. 
Thus, using acoustic tracks, Brill et al. (1993) presented 
evidence for passive, current-borne movements (which 
tended to drift in the prevailing current) for striped 
marlin around the Island of Hawaii. 
Our results revealed that swordfish were caught 
on days characterized by a weak lunar illumination. 
It is likely that increased illumination may alter the 
diving behavior of swordfish in near-surface waters. 
Ortega-Garcia et al. (2008) stated that vulnerability 
to gillnets was reduced because of better visibility 
during the full moon phase whereby swordfish could 
presumably detect and therefore avoid the net. As 
a logical extension, we could hypothesize that this 
visual avoidance could also apply to longline gear. In 
constrast, albacore exhibited higher CPUE during the 
full moon, which indicates increased foraging during 
the time of prey availability. This result supports that 
of Pusineri et al. (2008), who found that the composi- 
tion of the diet of pelagic predators in the northeast 
Atlantic differs considerably in terms of species com- 
position and prey size. 
Blue shark, the major shark found in bycatch of tuna 
and swordfish longline fisheries worldwide (Bonfil, 1994; 
Gilman et al., 2008) exhibited catch rates that corre- 
lated strongly with soak time but were not significantly 
influenced by lunar effects. To our knowledge, studies 
of the possible effect of lunar illumination on CPUE 
are rare for blue shark and virtually nonexistent for 
albacore and yellowfin tuna because these species are 
mainly caught during the day by Asian distant-water 
longline fleets. Our results agree with those of Bigelow 
et al. (1999), who showed that the effect of the moon 
phase appeared insignificant on blue shark CPUE. Blue 
shark are opportunistic feeders that are probably at- 
