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Fishery Bulletin 108(4) 
in postrelease mortality of fish caught on circle hooks 
compared to those caught on J hooks. In response to the 
depleted stock condition of Atlantic billfishes and the re- 
duction in undesirable hooking locations and postrelease 
mortality resulting from the use of circle hooks, NMFS 
in 2008 implemented a management measure requiring 
the use of non-offset circle hooks in natural baits for all 
Atlantic billfish tournaments. During the rule-making 
process, NMFS received several comments stating that 
blue marlin have lower rates of deep hooking with J 
hooks than white marlin or sailfish, especially when 
caught on artificial lure and natural bait combinations 
rigged with J hooks, a common terminal tackle used in 
the Atlantic recreational fishery. It was also suggested 
that blue marlin released from the recreational fishery 
have high rates of survival. 
Little is known about the effects of hook type on 
postrelease survival of blue marlin. A preliminary study 
on the use of PSATs to investigate postrelease survival 
of blue marlin inferred survival for at least eight of 
nine individuals caught on lures or skirted baits with J 
hooks trolled at relatively high speeds in the Bermuda 
recreational fishery (Graves et ah, 2002). Flowever, 
there were no data to directly compare the postrelease 
mortality of blue marlin caught on natural baits or on 
a combination of artificial lure and natural bait rigged 
with either circle hooks or J-hooks. To gain insights into 
the relative conservation benefits of circle hooks in the 
recreational fishery for Atlantic blue marlin and other 
istiophorids, we compiled data on hooking location and 
the incidence of trauma (bleeding) for 123 blue marlin, 
272 white marlin, and 132 sailfish caught on natural 
baits rigged with either J hooks or circle hooks. Fur- 
thermore, to estimate the postrelease mortality of blue 
marlin caught on natural baits with circle hooks or ar- 
tificial lure and natural bait combinations with J hooks, 
we deployed 61 PSATs to follow the fate of blue marlin 
caught on one of the two types of terminal tackle. 
Materials and methods 
Hooking location 
Information on hook type, hooking location, and trauma 
(the presence of bleeding) was collected by the authors 
for all blue marlin, white marlin, and sailfish caught 
on trolled plain (naked) ballyhoo ( Herniramphus brasil- 
iensis) baits during our PSAT tagging operations in the 
western North Atlantic from 2006 through 2009. Similar 
information was recorded by three cooperating charter 
captains (one from Oregon Inlet, NC, USA, and two 
from La Guaira, Venezuela) for billfishes caught during 
fishing operations in 2006. To accommodate captain and 
charter angler preferences, a variety of hook models and 
sizes were employed in the different fishing operations, 
but the most common J hook model was the Mustad 9175, 
size 7/0 (Mustad, Gjovik, Norway), and the most common 
circle hook model was the Eagle Claw L2004EWF, size 
8/0 (Eagle Claw, Denver, CO). As is typical for this fish- 
ery, circle hooks were left exposed, rigged to the head 
of the bait, whereas J hooks were inserted through the 
mouth of the bait fish with the tip exiting the ventral 
surface (Fig. 1, A and B). 
Baits were trolled at approximately 6 nm/hr (11.1 km/ 
hr) during daylight hours on 30-50 lb (13.6-22.7 kg) 
class fishing tackle. As billfish approached the trolled 
bait, anglers would typically decrease tension on the 
line for periods of 4-10 s, “dropping back” the ballyhoo 
bait to the feeding billfish, which provided time for the 
