FAD: Fish Aggregating Device or Fish Attracting Device? A new analysis of yellowfin tuna movements around floating objects

Tropical tuna are known to associate with floating objects. Because fish are easier to detect and to catch when around these objects, fishermen have extensively deployed a large number of artificial floating objects in the tropical oceans. Although such objects are referred to as Fish Aggregating Devices (FADs), there is yet no strong evidence that fish do show an aggregative behaviour around them. The high probability of finding tuna around FADs may be the result of an aggregation process (high density of fish because fish stay for a long time around FADs) as well as an attraction process (high flow of fish through FADs). We analysed the movements of 14 yellowfin tuna, Thunnus albacares, in relation to FADs moored in the Indian and Pacific Oceans (corresponding to all the published tracking data) to determine whether the observed movement patterns resulted from an aggregation or an attraction process. Tuna appeared to be attracted by FADs. In general, they did not stay for long close to the FADs reached, and so did not aggregate there. Some FADs may nevertheless act as Fish Aggregating Devices. The possible reasons why tuna associate with floating objects are discussed in the light of these results.

[1]  B. Heller.  Circular Statistics in Biology, Edward Batschelet. Academic Press, London & New York (1981), 371, Price $69.50 , 1983 .

[2]  A. Klimley,et al.  School fidelity and homing synchronicity of yellowfin tuna, Thunnus albacares , 1999 .

[3]  Pierre Fréon,et al.  Tropical tuna associated with floating objects: a simulation study of the meeting point hypothesis , 1999 .

[4]  K. Holland,et al.  HORIZONTAL AND VERTICAL MOVEMENTS OF YELLOWFIN AND BIGEYE TUNA ASSOCIATED WITH FISH AGGREGATING DEVICES , 1990 .

[5]  L. M. Marsh,et al.  The form and consequences of random walk movement models , 1988 .

[6]  Pierre Fréon,et al.  Review of fish associative behaviour: Toward a generalisation of the meeting point hypothesis , 2000, Reviews in Fish Biology and Fisheries.

[7]  I. Ohta,et al.  Aggregating Behavior of Yellowfin and Bigeye Tuna Tagged With Coded Ultrasonic Transmitters Around FADs in Okinawa, Japan , 2001 .

[8]  S. Benhamou,et al.  Spatial analysis of animals' movements using a correlated random walk model* , 1988 .

[9]  L. Dagorn,et al.  Simultaneous observations of tuna movements and their prey by sonic tracking and acoustic surveys , 1998, Hydrobiologia.

[10]  Simon Benhamou,et al.  Efficiency of area-concentrated searching behaviour in a continuous patchy environment* , 1992 .

[11]  Alain Fonteneau,et al.  A worldwide review of purse seine fisheries on FADs , 2000 .

[12]  John R. Sibert.  Electronic Tagging and Tracking in Marine Fisheries , 2001 .

[13]  P. Cayre.  Behaviour of yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelarnis) around fish aggregating devices (FADs) in the Comoros Islands as determined by ultrasonic tagging , 1991 .

[14]  Pierre Auger,et al.  Predator Migration Decisions, the Ideal Free Distribution, and Predator‐Prey Dynamics , 1999, The American Naturalist.

[15]  S. Benhamou.  On the expected net displacement of animals' random movements , 2004 .

[16]  Jean-Yves Le Gall,et al.  Pêche thonière et dispositifs de concentration de poissons , 1999 .

[17]  P. Cayré,et al.  Marquage acoustique et comportement de thons tropicaux (albacore : THUNNUS ALBACARES, et listao : KATSUWONUS PELAMIS) au voisinage d'un dispositif concentrateur de poissons , 1986 .

[18]  Simon Benhamou,et al.  Distinguishing between elementary orientation mechanisms by means of path analysis , 1992, Animal Behaviour.

[19]  Barbara A. Block,et al.  Horizontal movements and depth distribution of large adult yellowfin tuna (Thunnus albacares) near the Hawaiian Islands, recorded using ultrasonic telemetry: implications for the physiological ecology of pelagic fishes , 1999 .

[20]  F. Marsac,et al.  Telemetry applied to behaviour analysis of yellowfin tuna (Thunnus albacares, Bonnaterre, 1788) movements in a network of fish aggregating devices , 1998, Hydrobiologia.

[21]  L. Dagorn,et al.  Individual differences in horizontal movements of yellowfin tuna (Thunnus albacares) in nearshore areas in French Polynesia, determined using ultrasonic telemetry , 2000 .