50 
National Marine 
Fisheries Service 
NOAA 
Abstract— Identifying effective 
methods of reducing shark bycatch 
in hook-based fisheries has received 
little attention despite reports of 
declines in some shark populations. 
Previously proposed shark bycatch 
mitigation measures include gear 
modifications, time and area clo- 
sures, avoidance of areas with high 
shark abundance, use of repellents, 
and use of specific bait types. Re- 
gardless of the method of shark by- 
catch reduction, knowledge of the 
effects of the chosen method on the 
catch rates of targeted fish species 
should be understood. To examine 
the effects of bait type on catch 
rates of sharks and teleosts on bot- 
tom longline gear, standardized gear 
was deployed with bait alternating 
between Atlantic mackerel {Scomb- 
er scombrus) and northern shortfln 
squid (Illex illecebrosus). For all 
shark species examined, except the 
scalloped hammerhead (Sphyrna 
lewini), a preference for hooks baited 
with Atlantic mackerel was observed. 
Commercially and recreationally im- 
portant teleosts had no significant 
preference for a specific bait, with 
the exception of the red drum {Sci- 
aenops ocellatus), which had a sig- 
nificant preference for hooks baited 
with northern shortfin squid. Bait 
preference decreased as total catch 
rate increased on individual longline 
sets. Our results point to the use of 
specific baits as a viable method to 
reduce shark catch rates without de- 
creasing catches of targeted teleosts. 
Manuscript submitted 10 November 2015. 
Manuscript accepted 27 October 2016, 
Fish. Bull. 115:50-59 (2017). 
Online publication date: 10 November 2016. 
doi: 10.7755/FB.115.1.5 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery BuHetin 
^ established in 1881 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Inflyence of bait type on catch rates of 
predatoi^ fish species on bottom longline 
gear in the northern Gulf of Mexico 
William B. Driggers ill (contact author)' 
Matthew D. Campbell' 
Kristin M. Hannan^ 
Eric R. Hoffmayer' 
Christian M. Jones' 
Lisa M. Jones' 
Adam G. Pollack^ 
Email address for contact author: william.driggers@noaa.gov 
' Mississippi Laboratories 
Southeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
P.O. Drawer 1207 
Pascagoula, Mississippi 39567 
2 Riverside Technology Inc. 
Mississippi Laboratories 
Southeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
P.O. Drawer 1207 
Pascagoula, Mississippi 39567 
Because of reported declines in 
some shark populations, there has 
been increasing interest in mitigat- 
ing bycatch rates of shark species in 
longline fisheries that target teleosts 
(Francis et al., 2001; Beerkircher et 
al., 2002; Gilman et al., 2008; Ward 
et al., 2008). Within the northern 
Gulf of Mexico, commercial fishing 
for sharks has occurred since the 
1920s (Rogers, 1920) and continues 
to present day. Although directed 
commercial fishing effort for sharks 
in the region has waxed and waned 
over the years, shark bycatch con- 
tinues to be an important source of 
mortality, particularly in hook-based 
fisheries, such as the snapper and 
grouper bottom longline fishery (e.g., 
Scott-Denton et a!., 2011). 
Proposed or enacted efforts to cur- 
tail shark bycatch in longline fisher- 
ies have included gear modifications 
(Ward et al., 2008), reductions in 
gear soak time (Carruthers et al., 
2011), adjustments in fishing depth 
(Rey and Mueoz-Chapuli, 1991), time 
and area closures (Watson et al., 
2009), avoidance of areas of known 
high shark abundance (Walsh et al., 
2009), use of repellents (Robbins et 
al., 2011) and use of specific bait 
types (Gilman et aL, 2007). Ultimate- 
ly, for any bycatch reduction method 
to be fully embraced within a fishery, 
it will be necessary that catch rates 
of targeted species not be negatively 
affected when a specific approach is 
applied. Ideally, a bycatch reduction 
approach would minimize bycatch 
rates and not affect catch rates of 
target species and cause the least 
amount of economic hardship and 
changes to proven fishing practices. 
Among measures proposed to miti- 
gate shark bycatch, use of bait that 
