A) Gears and fishing techniques
Based on 54 fishing trips in Martinique on professional fisherfolk’s skiffs between August 2003 and April 2004, a description of the fishing techniques, specific composition, size and location regarding the FAD’s buoy was made. (Reynal et al. 2007)
The gears used are exclusively lines. At day time, two 100-meter lines are dragged at an average speed of 4,5 knots, equipped with a hook and a lure. The lure comes into several shapes (octopus, worm…) and colors. Fisherfolk have recently started to use more sophisticated lures such as the popper. One of the lines is lightly weighted in order to remain in the subsurface and not be cut by the propellers of other vessels working around the FAD. Its average weight is 180 g and reaches, according to calculations made with the « DCP » software, (Lebeau et al. 2004) an average depth of 4 m. The other line is weighted with a cable and lead weighing 1280 g on average and allegedly reaches an average 11 m deep. The maximum and minimum dragging speeds calculated from 236 measurements around the FADs were between 1,6 and 7,4 knots. The minimum and maximum depths reached by the surface trolling lines could range between 1,9 and 9,8 m, and between 3,6 and 25 m for the deep trolling line.
Seven to fifteen vertical drifting longlines with one hook compose a skiff’s fishing arsenal. These gears generally use small live tuna captured with trolling lines as baits. In some cases flying fish are fished with a net to serve as baits. Pieces of tuna can be cut (« Bouchon » or « Dolle ») and placed on the hooks. Sometimes they are shaped like flying fish (« volant bois-bois”). These longlines are set upstream of the FAD and left drifting. As baits often lack, fisherfolk spend most of their time hanging about to catch small tuna and they rarely put all their vertical longlines at sea at the same time. Those longlines are meant to reach different depths (between 20 and 200 m), which allows to look for the best depth in order to optimize the fishing of marlins and large yellow tuna.
At nighttime, generally between 4 and 6 AM – sometimes earlier when the moon is full, the fishing of subsurface black tuna occurs when they come back and aggregate close to the FAD and is performed with deep trolling lines with one or several hooks with a phosphorescent lure. These average 80-meter-long lines are weighted with a 2 to 2,5 mm cable and lead amounting 1800 g. The average dragging speed was evaluated to 5 knots and the fishing depth to an average 11 m with minimum and maximum values of 7 and 32 meters. No other device is used during very short fishing period.
Fishing depth of the main gears used around anchored FADs
La dorade coryphène est capturée à l’aide de lignes appâtées appelées « chasseurs » (Guillou et Lagin 1997).Cette technique de pêche consiste à maintenir le premier poisson capturé le long du bord afin d’attirer les autres individus. Très grégaire, la dorade est un poisson vivant en banc conduit par un mâle dominant. Ces bancs sont relativement réduits par rapport à ceux de thon et se placent à proximité d’épave dérivante. C’est la raison pour laquelle les pêcheurs qui veulent cibler cette espèce multiplient le nombre de DCP, comme cela se fait en Guadeloupe.
Certaines techniques de pêche observées au début du développement des DCP dans les Antilles françaises semblent avoir disparu. Il s’agit de la pêche en dérive qui consiste à laisser dériver l’embarcation avec 3 lignes de forte résistance, à différents niveaux de profondeur, appâtées de poissons volants ou de morceaux de thon frais. Certains pêcheurs amarrent leur embarcation à un filet à volants dont il se serve à la fois d’encre flottante et d’engin de capture de poisson volants dont ils se servent comme appât. Cette technique semble avoir été remplacée par la palangre verticale dérivante à un hameçon. La pêche en position fixe dite « à soutenir » ou « bout au vent » se pratique de la même façon que la précédente, mais dans ce cas le navire ne dérive pas. Il est maintenu en position fixe par un rameur et autour de la ligne sont jetés des ingrédients-d’appâts de compostions divers. Ceux-ci permettent d’attirer autour des lignes les grands pélagiques que les pêcheurs essaient de capturer jusqu’à une centaine de mètres de profondeur (Guillou et Lagin, 1997).
In the beginning of the 2010’s, jigging started to develop around anchored FADs. This technique uses a fishing cane and a leaded lure (Dromer 2011). It is practiced from a drifting vessel and exploits the water column as deep a 100 m. It is mainly used to catch intermediate size tuna such as adult black fin tuna.
Model of jig used near anchored FADs
In Haïti, in the region of Leogane, fisherfolk performing FAD fishing with dug wood set small FADs about 10 km from the shore under which they set a fish-trap made of bamboo to capture small coastal pelagic Carangidae (Decapterus tabl). Those fishes are kept alive in small basins and are used as live baits for fishing with a single-hook vertical longline. As the dug tree trunks they use as vessels do not have an engine, these fisherfolk cannot use trolling lines around the FADs.
Lifting of a fish-trap set under a FAD to capture small pelagic fishes used as baits on drifting lines
Live baits are placed in a basin whose water is regularly changed with a scoop
B) Quantification and localization of the catches around the FADs
The detailed analysis of 40 fishing trips made in Martinique in 2003 and 2004 enables the counting of catches. During those fishing trips, 545 catches were made with surface and deep lines and 508 vertical longlines were set (average of 12,7 per trip). Thanks to them, 62 fishes were fished. Live baits were used on 402 longlines and dead baits (frozen fish or fillet of fish dead after several uses while alive) for 106 of them. Live baits are mainly juveniles (92%). The number of juveniles fished per trip is 11,5 on average (79% of the catches). Those juveniles are not all landed because some of them are lost during longline fishing trips. It is worth noting that if the small tuna come back ashore in a good general condition after being used as baits, they may be landed and sold.
The captures of fish mostly occur upstream of the current regarding the FADs (68% of the catches) and very close to the FADs (82% at less than 400 m). The space exploited by the fisherfolk around FADs is of 300 ha but the catches made during the 14 professional fishing trips studied were made on 160 ha only.
Localization of the fishing gears and captures around anchored FADs