Driggers et al.: Influence of bait type on catch rates of predatory fish on longiine gear 
57 
coastal shark species that are not reef obligate or con- 
strained within a bounded area (e.g., bay or estuary) 
can be up to 100 km^. For example, through acoustic 
monitoring, Heupel et al. (2006) determined the mean 
home range of the bonnethead {Sphyrna tiburo) was 
8.31 km^; however, some individuals used areas of up 
to approximately 74 km^. Larger-bodied species, such 
as the tiger shark, have been documented to have vast 
home ranges, on the order of 1000s of square kilome- 
ters (Heithaus et al., 2007). 
Conversely, most of the teleosts that we captured, 
with the exception of the red drum, are relatively sed- 
entary and have a high degree of site fidelity in off- 
shore waters to discrete structures, such as lumps and 
depressions (e.g., Able et al., 1993; Gallaway et al., 
2009). For example, Jones et al. (1989) documented 
tilefish and yellowedge grouper in the western Gulf of 
Mexico occupying discrete burrows with openings rang- 
ing from 0.25 to 8 m wide. Able et al. (1982) hypothe- 
sized that these structures serve as refuge from preda- 
tors, and Jones et al. (1989) suggested that individuals 
have long-term fidelity to specific burrows. Although it 
is unknown how far these individuals move from their 
burrows to forage, the aforementioned studies all indi- 
cate that, in contrast with coastal shark species, most 
teleost species that we examined remain in relatively 
close proximity to a specific location. Therefore, it is 
possible that the teleosts that exhibited this behavior 
in our study were attracted to bait on the basis of prox- 
imity rather than preference. 
In contrast, because shark species rely, in part, on 
chemotaxis to locate prey from a distance (e.g., Shel- 
don, 1911; Lpkkeborg et al., 2014), it is possible that 
the area of bait influence was greater for Atlantic 
mackerel than for northern shortfin squid and led to 
sharks homing in more frequently on hooks baited with 
Atlantic mackerel. Chemotaxis, however, is unlikely to 
have affected bait preference given the relatively close 
gangion spacing (~ 18 m apart), diffusion and mixing 
of scent plumes from individual baits with increasing 
distance from the gear, and the setting of gear parallel 
to the axis of a current that resulted in a single plume 
of odorants from both Atlantic mackerel and northern 
shortfin squid. Therefore, given that these 2 species 
have significantly different relative concentrations of 
low-molecular-weight metabolites that are known at- 
tractants or stimulants of feeding behavior in fish spe- 
cies (Carr et al., 1996), it is more likely that higher 
catch rates of most shark species on hooks baited with 
Atlantic mackerel was a result of preference and not 
the area of bait influence. 
A potential criticism of our study is that we used 
alternating bait types on each longiine set rather than 
making comparisons on the basis of single-bait sets. 
Although numerous bait preference studies have used 
an alternating bait design similar to the one in our 
study (e.g., Broadhurst and Hazin, 2001; Woll et al., 
2001; Yokota et al., 2009), it was suggested by Watson 
et al. (2005) and Foster et al. (2012) that the use of 
alternating bait types can bias results because of a po- 
tential interaction effect of bait types. Both Watson et 
al. (2005) and Foster et al. (2012) examined effects of 
bait and hook type on catch rates of epipelagic organ- 
isms caught on pelagic longiine gear and therefore they 
focused on highly mobile species, such as sea turtles, 
sharks, swordfish, and tunas, that occupy a single habi- 
tat (epipelagic zone). 
Conversely, we used bottom longiine gear in a highly 
dynamic area in terms of prey density, foraging behav- 
iors of target species, currents, depth, dissolved oxy- 
gen, salinity, temperature, turbidity, substrate types, 
and patchy habitats. Therefore, because many of these 
variables affect feeding behavior and the ability of fish 
species to locate baited hooks (Lpkkeborg et al., 2014), 
we believe the use of alternating bait types is justi- 
fied and best suited to answer the questions we were 
addressing. Had we used a single-bait approach, we 
would have needed to account for each of the biotic and 
abiotic variables for individual longiine sets. However, 
although we acknowledge that the use of alternating 
bait types could have introduced a potential bait inter- 
action effect, we did expose an equal number of both 
bait types to all conditions encountered, thereby limit- 
ing the number of potentially biasing factors to one. 
Additionally, several of the species we encountered 
are infrequently captured and occur in large aggrega- 
tions. For example, of the 79 little gulper sharks col- 
lected, 62% were caught on 2 sets. Further, although 
little gulper sharks are infrequently captured in shelf 
waters of the northern Gulf of Mexico, when present, 
they are found in large schools (senior author, personal 
observ.). Had single-bait sets been used and had a set 
occurred in proximity to a school of little gulper sharks, 
the resulting data would be indicative of the high den- 
sity of little gulper sharks in the area and not of a 
preference for a specific bait type. 
Ward et al. (2004) examined the theoretical effect 
of hook soak time on pelagic longiine catches in the 
Pacific Ocean and determined that catch rates can be 
affected by, among other issues, baits falling off during 
deployment of longiine sets, by deterioration that re- 
sults in baits falling off hooks, or by a time-related re- 
duction in the degree of attraction. Godin et al. (2012), 
in a metadata analysis, stated that the catch of sharks, 
in general, was reduced when Atlantic mackerel were 
used as bait. They went on to reason that squid, when 
compared to mackerel, was a more effective bait be- 
cause it remains on hooks longer, does not deteriorate 
as rapidly, and does not lose its attraction properties 
over time. 
Although we were not able to quantify the attrac- 
tant properties of the 2 bait types, our results are in 
direct opposition to those of Godin et al. (2012) in that 
we found both bait types were retained on hooks equal- 
ly and that bait damage or loss was greater for hooks 
baited with northern shortfin squid. The disparity in 
the 2 studies is likely attributable to the data sources 
of Godin et al. (2012) primarily reporting catch of blue 
sharks and to differences in hook soak times among 
studies. For example, Godin et al. (2012) included fish- 
