212 
Fishery Bulletin 99(1 ) 
Geographic location of ten pelagic longline sets conducted off Georges Bank 
between 22 July and 2 August 1999, to examine the catches of pelagic species on 
monofilament and tarred multifilament nylon gangions. 
all commercial-size swordfish (i.e. >119 
cm LJFL) by using a metal tape mea- 
sure. No measurements were obtained 
for live or dead under-size swordfish (i.e. 
<119 cm LJFL based on visual estima- 
tion); however, their catch was recorded. 
Under-size swordfish were not brought 
aboard the vessel but were released in 
the water by cutting the gangion as close 
to the hook as possible. Other species 
were not measured because most of these 
were also released alive after capture. 
Chi-square (% 2 ) was used to determine 
if the observed frequency of catches by 
gangion type for each species differed sig- 
nificantly (a<0.05) from an expected 1:1 
ratio for individual and combined sets. 
Catches of commercial-size and under- 
size swordfish were combined for this 
analysis because the method for size de- 
termination of under-size fish was con- 
sidered too subjective for a separate anal- 
ysis by size category. Only cases where 
10 or more observations were available 
for each species were used for within-set 
comparisons. Because very few captures 
of any species occurred on gangions 
with lightsticks attached, the influence 
of lightsticks on catch rates in this experiment were as- 
sumed to be negligible, even though they are often used by 
fishermen (at much higher deployment rates) to improve 
catches of swordfish. A two-way ANOVA was used to ex- 
amine differences in the mean lengths (LJFL) of commer- 
cial-size swordfish >119 cm LJFL) by set and gangion type 
after testing for homogeneity of variances. 
Results 
The primary species captured included swordfish (Xiphias 
gladius), blue shark ( Prionace glauca), shortfin mako 
shark (Isuj-us oxyrinchus), pelagic stingray (Dasyatis vio- 
lacea), loggerhead turtle ( Caretta caretta), white marlin 
( Tetrapturus albidus), common dolphinfish (Coryphaena 
hippurus) and yellowfin tuna ( Thunnus albacares). A total 
of 1093 captures (all eight species combined) occurred from 
10 pelagic longline sets, with 66.7% of captures occurring 
on monofilament and 33.3% on multifilament gangions. 
Catches of swordfish averaged 38.8 fish per set (based 
on 334 kept plus 54 released as under-size), followed by 
blue shark (34.1/set), shortfin mako shark (9.7/set), pelagic 
stingray (9.4/set), loggerhead turtle (6.6/set), white marlin 
(6.0/set), common dolphinfish (3.7/set), and yellowfin tuna 
(1.0/set). 
Commercial-size swordfish ranged from 120 to 242 cm 
LJFL (mean=154.4 ±21.14, n= 334). Swordfish captured 
on monofilament nylon and multifilament nylon gangions 
were very similar in mean length (154.7 ±21.66 and 153.8 
±20.18 cm LJFL, respectively) and overall size composi- 
tion (Fig. 4). There was no significant difference between 
mean lengths of commercial-size swordfish by set or gan- 
gion type, nor was there evidence of an interaction be- 
tween these factors (F=0.736, P=0.690, df=333, 19), indi- 
cating that there were no size-related preferences for one 
gangion type over the other for swordfish >119 cm LJFL. 
Observed swordfish captures by gangion type differed 
significantly from an expected 1:1 ratio in all but two of 
the 10 sets, with higher catches on monofilament gangions 
compared with the multifilament (Table 1). Similarly, ob- 
served captures of blue sharks differed significantly from 
expected in 3 of 10 sets, with higher catches on the mono- 
filament gangions. For all other species, fewer than 10 sets 
were available for x 2 comparisons because less than 10 in- 
dividuals were captured for some sets. In the case of ma- 
ko shark, only 5 of 10 sets had sample sizes >10, but no 
significant difference occurred between the observed and 
expected catch frequency by gangion type, although more 
captures occurred on monofilament gangions for most sets. 
For white marlin and loggerhead turtle, only 2 of 10 sets 
had sample sizes >10 and showed no significant differ- 
ences in catch by gangion type, although most occurred 
on monofilament. However, for pelagic stingrays, 3 out of 
4 sets available for comparison showed significant differ- 
ences between observed and expected catches by gangion 
type, with higher catches on the monofilament gangions. 
The catch per set of yellowfin tuna and common dolphin- 
fish was too low for statistical comparisons. Captures of all 
species combined were significantly higher on monofila- 
ment gangions for 9 out of 10 sets (Table 1). 
For all species, 60% or more of catches from combined 
sets occurred on monofilament gangions (Table 2). When 
the catches by species for all 10 sets were pooled, the 
