Like sharks, barracudas have a bad reputation as being dangerous to humans. As barracudas are also scavengers, they may mistake snorkelers for large predators and follow them in the hopes of scavenging the remains of an attack on prey.
Shark populations are in danger for several reasons. One of them is over fishing. Outside of the US, shark is quite a popular dish.
Aquaculture is going to be part of the next generation's future. You can help feed the world if you research and develop the science of farming fish.