Great barracuda social behavior

HEAVY CONSTRUCTION ZONE!

As we have already seen, many barracuda species habitually school, in large schools that may include hundreds or even thousands of individuals. Advantages of schooling can include both defensive (predator-avoidance) and offensive (feeding) gains. Schools attacked by a predator often explode into a confusing fountain of flashing bodies, making it difficult for the predator to maintain a fix on any one fish. Alternatively, the school may separate around the predator, flowing around it but maintaining a zone of safety between it and them. The increased vigilance of the school, a result of having many eyes on the lookout for threat of predation, is also beneficial in detecting patches of food, or concentrations of prey. In this case, even though the rewards may be divided between more mouths, the overall payoff may be increased foraging efficiency thanks to better, earlier, and more frequent detection of food. It is also conceivable that the defenses of schooling fishes can best be overcome by schooling predators — this mode of foraging exists in orcas and (in a parallel sense) terrestrial carnivores and in piscivores such as jacks, but whether fishes hunt cooperatively in such a group fashion remains a subject of some debate.

Although large groups of young great barracuda have been described, adults have long been considered as generally being solitary 'lone wolves' on the prowl for food. My graduate research included the observation that adult great baracuda commonly form aggregations, and that a good percentage of barracuda at my study sites in the Turks and Caicos Islands and Florida Keys occurred in these groups. The groups can be very large, too — the largest group of great barracuda that I have yet seen would be somewhere in the region of 100 individuals, though I have heard of groups that included thousands of large barracuda. The dichotomy between grouped and solitary behavior may to some degree reflect the noticeable differences in behavior among individual barracuda.

Evidence for cooperative foraging by groups of small barracuda can be found in a few papers: a group is able to scatter a school of small fishes and pick off the scattered individuals whereas a single great barracuda may not be able to. In these cases, groups formed following flood tide, when schools of gerreids, clupeids, and atherinids move toward very shallow inshore zones. I have experienced two juvenile (1.5') great barracuda coming to inspect me together, both oriented tail-down and head-on to me at a distance of about four feet, forming a 90 degree angle horizontally. The ensuing standoff was nerve-wracking despite their relatively small size, and was compounded by their cryptic coloration and separation that forced me to constantly turn my head to monitor them. Just as inexplicably, the two barracuda left. In his 1963 scientific paper, de Sylva recounts being virtually surrounded by somewhat larger young individuals in the Bahamas that maintained a constant distance from him whether he moved forward or back.