Buencuerpo et a!.: Pelagic sharks associated with the swordfish fishery 
671 
swordfish in only one of nine months sampled for 
gillnet landings. 
Shortfin mako shark 
Longline catch rates are shown in Table 5; Atlantic 
catch rates were always higher than those in the 
Mediterranean. Variation in the longline catch rate 
(Table 6) was at a minimum in December and May, 
peaking in April and September. In gillnet fishing 
(Table 7), shortfin mako shark catch rates were rela- 
tively lower than swordfish catch rates. 
Table 8 gives biometrical information by sex, and 
longline and gillnet frequency distributions of dif- 
ferent lengths by sex are presented in Figures 3 and 
4. The distribution was not significantly different 
between sexes in longline (x 2 =54.4; df=39; P>0.05) 
and gillnet (% 2 =20.5; df=23; P> 0.5) landings. The dis- 
tribution by size of males varied significantly by sec- 
tor (F= 28.796; df=5, 1428; P<0.001). The distribu- 
tion by size of females also varied significantly by 
sector (F=14.985; df=5, 1429; PcO.OOl). 
The maximum size of females landed by longlines 
tended to increase from sector 1 to sector 3 (Fig. 5A). 
The maximum size of males tended to increase in 
Atlantic sectors from south to north (Fig. 5B). Small- 
est maximum sizes for both sexes occurred in the 
Mediterranean Sea, and in sector 1 for males. Gill 
nets catch bigger females and smaller males than do 
longlines in the same sector. The monthly variations 
Table 4 
Monthly longline and gillnet catch distribution for the five most important shark species and for swordfish by number of fish in) 
and percentage (%). Species codes: 10 
= Isurus oxyrinchus\ PG 
= Prionace glauca\ AV = Alopias vulpi 
nus\ AS = 
Alopias superciliosus; 
SZ = Sphyrna zygaena; TOT-SHX = Total sharks; XG = Xiph 
ias gladius; 
IO 
PG 
AV 
AS 
SZ 
TOT-SHX 
XG 
Total 
Gear and 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
month 
Longline 
Jul 91 
224 
16.85 
992 
74.64 
2 
0.15 
31 
2.33 
21 
1.58 
1270 
95.56 
59 
4.44 
1329 
Aug 91 
891 
19.96 
2865 
64.19 
1 
0.02 
3 
0.07 
147 
3.29 
3907 
87.54 
556 
12.46 
4463 
Sep 91 
422 
15.93 
2158 
81.46 
0 
0 
7 
0.26 
28 
1.06 
2615 
98.72 
34 
1.28 
2649 
Oct 91 
584 
9.57 
3338 
54.68 
0 
0 
32 
0.52 
131 
2.15 
4085 
66.91 
2020 
33.09 
6105 
Nov 91 
970 
14.10 
4333 
62.99 
4 
0.06 
25 
0.36 
252 
3.66 
5584 
81.17 
1295 
18.83 
6879 
Dec 91 
30 
12.35 
105 
43.21 
0 
0 
5 
2.06 
0 
0 
140 
57.61 
103 
42.39 
243 
Jan 92 
863 
10.02 
6117 
71.03 
4 
0.05 
110 
1.28 
30 
0.35 
7124 
82.72 
1488 
17.28 
8612 
Feb 92 
868 
9.07 
6988 
73.03 
2 
0.02 
135 
1.41 
79 
0.83 
8072 
84.36 
1497 
15.64 
9569 
Mar 92 
423 
9.04 
3208 
68.53 
1 
0.02 
54 
1.15 
1 
0.02 
3687 
78.77 
994 
21.23 
4681 
Apr 92 
109 
10.64 
913 
89.16 
0 
0 
1 
0.10 
0 
0 
1023 
99.90 
1 
0.10 
1024 
May 92 
25 
8.01 
283 
90.71 
1 
0.32 
0 
0 
0 
0 
309 
99.04 
3 
0.96 
312 
Jun 92 
114 
10.45 
783 
71.77 
1 
0.09 
8 
0.73 
2 
0.18 
908 
83.23 
183 
16.77 
1091 
Jul 92 
70 
15.28 
366 
79.91 
0 
0 
0 
0 
12 
2.62 
448 
97.82 
10 
2.18 
458 
Total 
5593 
11.80 
32449 
68.44 
16 
0.03 
411 
0.87 
703 
1.48 
39172 
82.62 
8243 
17.38 
47415 
Gear and 
IO 
PG 
AV 
AS 
SZ 
TOT-SHX 
XG 
Total 
month 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
% 
n 
Gillnet 
Jul 91 
Aug 91 
19 
7.39 
0 
0 
i 
0.39 
37 
14.40 
5 
1.95 
62 
24.12 
195 
75.88 
257 
Sep 91 
106 
22.70 
30 
6.42 
2 
0.43 
27 
5.78 
22 
4.71 
187 
40.04 
280 
59.96 
467 
Oct 91 
Nov 91 
53 
9.62 
2 
0.36 
0 
0 
3 
0.54 
12 
2.18 
70 
12.70 
481 
87.30 
551 
Dec 91 
Jan 92 
Feb 92 
Mar 92 
6 
6.25 
0 
0 
15 
15.6 
0 
0 
1 
1.04 
22 
22.92 
74 
77.08 
96 
0 
0 
1 
33.33 
0 
0 
0 
0 
0 
0 
1 
33.33 
2 
66.67 
3 
Apr 92 
54 
24.00 
83 
36.89 
15 
6.67 
7 
3.11 
2 
0.89 
161 
71.56 
64 
28.44 
225 
May 92 
76 
11.66 
90 
13.80 
1 
0.15 
0 
0 
0 
0 
167 
25.61 
485 
74.39 
652 
Jun 92 
14 
15.22 
1 
1.09 
0 
0 
6 
6.52 
4 
4.35 
25 
27.17 
67 
72.83 
92 
Jul 92 
26 
12.62 
5 
2.43 
2 
0.97 
66 
32.04 
8 
3.88 
107 
51.94 
99 
48.06 
206 
Total 
354 
13.89 
212 
8.32 
36 
1.41 
146 
5.73 
54 
2.12 
802 
^1.46 
1747 
68.54 
2549 
