Shark Depredation and Unwanted Bycatch in Pelagic Longline

Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries
Table A2.2. Fishing gear characteristics of the Chilean longline fishery (from surveys and Barria et al., 2006).
Gear Characteristic
Artisanal Mahi Mahi
Spanish System
Industrial swordfish
American System
Mainline material
Mainline length
Multifilament
4-5mm Ø
1500-2000 fathoms
(2.7–3.7 km)
Polypropylene
Multifilament
6mm Ø
45 nautical miles
(83 km)
Monofilament
3.5mm Ø
35-55 nautical miles
(64-101 km)
Mainline deployment Superficial Mid-water Mid-water
Distance between buoys 18-36 m (10-20 fm) 4.5 km varies
Distance from buoy to mainline
(float line length)
NA 10 fathoms 10 fathoms
Average branch line length 9.1 m (5 fm) 8.2 m (4.5 fm) 16.5 m (9 fm)
Branch line material Monofilament polypropylene Monofilament 20mm Ø
Wire trace or leader on branch lines Sometimes Yes or no Yes
Number of hooks between buoys 1 110 220-250
Average maximum depth of hooks when set 6-8 fathoms 70m 70m
Average maximum depth of mainline when set Superficial 50m 50m
Mainline sink rate No information No information 90 m in 16 seconds
Timing of set, soak, and haul Set: 7 AM (for 2-6 h)
Soak: surveying the line several
times a day
Haul: 4 to 5 PM (for 3-4 h)
Set: 6-8 PM (for 4 h)
Soak: 20h
Haul: 8AM (for 8 h)
Set: 6PM (for 4 h)
Soak: 8h
Haul: 8AM (for 6 h)
Lightstick use No Plastic polymer chemical or battery
Number of hooks per set 100-350 1500 1200-2000
Hook setting interval No information No information 8-16 seconds
Radio beacons No Yes Yes
Hook type J 0,1,2,3 (10 o offset) J17 Ancora (no offset)
J18 Ancora (no offset or 10 o offset)
Weight size and location NA 60 g. at connection of mainline
with float line
Clip size and type NA 350S 350S
J Mustad 9 (10 o offset)
80 g. at connection of mainline
with float line 65-75 g. swivel at
top of leader
Bait type Mackerel and sardine Squid or mackerel Squid and mackerel
Number of crew 2-3 12-15 8-10
Vessel Monitoring System No No No
Table A2.3. Catch per unit effort of sharks of the artisanal shark fleet, 2003-2005 (Barria et al., 2006).
Yield (g/hook)
2003 2004 2005
Month Mako Blue Total Mako Blue Total Mako Blue Total
Jan 194.3 22.7 217.0 245.6 8.5 254.1 314.6 9.5 324.1
Feb 265.2 22.5 287.7 401.3 9.1 410.5 301.8 8.1 309.9
Mar 382.2 47.8 430.0 236.5 17.3 253.8 269.1 55.8 325.0
Apr 281.3 58.8 340.1 290.6 38.9 329.5 232.6 69.1 301.7
May 154.2 28.1 182.3 249.4 35.0 284.4 261.8 85.9 347.7
Jun 160.3 57.1 217.5 168.7 31.7 200.4 85.4 68.8 154.2
Jul 27.5 11.7 39.3 78.9 82.6 161.4 74.2 37.0 111.3
Aug 52.9 29.6 82.4 75.6 97.5 173.1 91.1 55.8 146.9
Sep 141.5 50.6 192.1 119.0 62.2 181.2 45.8 119.1 164.9
Oct 172.7 78.1 250.8 183.9 49.5 233.5 58.9 147.6 206.5
Nov 188.6 37.5 226.2 283.5 40.8 324.3 295.5 71.9 367.5
Dec 208.9 15.5 224.3 224.0 14.1 238.1 160.4 25.6 186.0
Total 216.9 37.5 254.4 249.8 26.9 276.7 235.9 41.8 277.7
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